U.S. patent application number 17/412805 was filed with the patent office on 2021-12-16 for absorbent article with heat activatable web.
The applicant listed for this patent is The Procter & Gamble Company. Invention is credited to Kelyn Anne ARORA, Misael Omar AVILES, Holger BERUDA, Thomas BROCH, Jan CLAUSSEN, Gueltekin ERDEM, Morten Rise HANSEN, Barbara Harling HEDE, Olaf Erik Alexander ISELE, Franz Josef LANYI, Torsten LINDNER, Dirk Wolfram SCHUBERT, Brian UDENGAARD, Nathan Ray WHITELY.
Application Number | 20210386905 17/412805 |
Document ID | / |
Family ID | 1000005798699 |
Filed Date | 2021-12-16 |
United States Patent
Application |
20210386905 |
Kind Code |
A1 |
LINDNER; Torsten ; et
al. |
December 16, 2021 |
ABSORBENT ARTICLE WITH HEAT ACTIVATABLE WEB
Abstract
Material webs suitable for use in conjunction with disposable
absorbent articles are disclosed herein. The material webs comprise
a melt additive that when subjected to thermal energy may be
encouraged to bloom across the entirety of the web or in localized
areas of the web where localized thermal energy is applied.
Inventors: |
LINDNER; Torsten; (Kronberg,
DE) ; ISELE; Olaf Erik Alexander; (Wester Chester,
OH) ; ERDEM; Gueltekin; (Hessen, DE) ; AVILES;
Misael Omar; (Hamilton, OH) ; BERUDA; Holger;
(Schwalbach am Taunus, DE) ; CLAUSSEN; Jan;
(Wiesbaden, DE) ; ARORA; Kelyn Anne; (Cincinnati,
OH) ; WHITELY; Nathan Ray; (Liberty Township, OH)
; LANYI; Franz Josef; (Erlangen, DE) ; SCHUBERT;
Dirk Wolfram; (Eggolsheim, DE) ; HEDE; Barbara
Harling; (Aalborg, DK) ; BROCH; Thomas;
(Gistrup, DK) ; HANSEN; Morten Rise; (Aalborg,
DK) ; UDENGAARD; Brian; (Lystrup, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Procter & Gamble Company |
Cincinnati |
OH |
US |
|
|
Family ID: |
1000005798699 |
Appl. No.: |
17/412805 |
Filed: |
August 26, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15454128 |
Mar 9, 2017 |
11129919 |
|
|
17412805 |
|
|
|
|
62305726 |
Mar 9, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 13/512 20130101;
A61F 13/49 20130101; A61F 13/51113 20130101; A61F 13/513 20130101;
A61F 13/15617 20130101; A61L 15/42 20130101; C07F 9/6561 20130101;
A61F 2013/51078 20130101; A61F 13/47 20130101; A61F 2013/51026
20130101; A61F 13/51405 20130101 |
International
Class: |
A61L 15/42 20060101
A61L015/42; A61F 13/514 20060101 A61F013/514; A61F 13/513 20060101
A61F013/513; A61F 13/511 20060101 A61F013/511; C07F 9/6561 20060101
C07F009/6561; A61F 13/15 20060101 A61F013/15; A61F 13/47 20060101
A61F013/47; A61F 13/49 20060101 A61F013/49; A61F 13/512 20060101
A61F013/512 |
Claims
1-20. (canceled)
21. An absorbent article comprising: a topsheet; a backsheet; an
absorbent core disposed between the topsheet and the backsheet; and
a material web forming a portion of the absorbent article, the
material web having a first surface and an opposing second surface,
and wherein the material web comprises a thermoplastic polymeric
material and a melt additive homogeneously mixed with the
thermoplastic polymeric material and melt additive bloom areas
disposed on the first surface, and wherein the thermoplastic
polymeric material and the melt additive are matched to discourage
auto blooming of the melt additive at room temperature; wherein the
material web further comprises a plurality of apertures; and
wherein said melt additive bloom areas comprise a first portion
surrounding said apertures and a second portion defined by melt
lips of said apertures, wherein said first portion comprises a
higher percentage of melt blooming than said second portion.
22. The absorbent article of claim 21, wherein the material web
forms a portion of the topsheet.
23. The absorbent article of claim 21, wherein the melt additive
bloom areas are more hydrophobic than the thermoplastic polymeric
material as determined by the Scanning Electron Microscope (SEM)
Method for determining contact angle on fibers.
24. The absorbent article of claim 21, wherein the material web is
a nonwoven material comprising a plurality of staple length
fibers.
25. The absorbent article of claim 24, wherein a first plurality of
staple length fibers comprise the melt additive and a second
plurality of staple length fibers do not comprise the melt additive
of the first plurality of staple length fibers.
26. The absorbent article according to claim 21, wherein the
material web is a nonwoven material comprising continuous
filaments.
27. The absorbent article of claim 21, wherein a first migration
coefficient of the melt additive bloom areas is at least two times
a second migration coefficient of a non-activated area of the
thermoplastic polymeric material.
28. The absorbent article of claim 21, wherein the material web
comprises the thermoplastic polymeric material, the melt additive,
and an additive which influences crystallinity of the thermoplastic
polymeric material, the additive being selected from at least one
of a nucleating agent, branched polymers, or random
co-polymers.
29. The absorbent article of claim 21, wherein said melt additive
bloom areas are in the form of a film, flakes, fibrils, or
combinations thereof.
Description
FIELD OF THE INVENTION
[0001] The disclosure herein relates generally to thermoplastic
polymeric materials with varying property zones created via the
application of thermal energy and articles incorporating such
materials.
BACKGROUND OF THE INVENTION
[0002] Nonwovens and films have been used in a myriad of absorbent
articles over the past several years. In some particular absorbent
articles, e.g. diapers, feminine hygiene pads, nonwovens and/or
films may be utilized as a topsheet, backsheet, or some other
feature of these particular absorbent articles.
[0003] The requirements for these absorbent articles may be
disparate depending use. For example, a nonwoven and/or film used
as a topsheet for diapers may not be suitable for adult
incontinence products. Similarly, a nonwoven and/or film suitable
as a topsheet for adult incontinence products may not be suitable
for feminine hygiene pads.
[0004] Additionally, requirements for nonwoven and/or films in
absorbent articles may vary by geography. For example, in one
geography an absorbent article with a soft topsheet may be a factor
which is foremost in consumer's minds. In another geography,
absorbent articles which minimize the amount of rewet may be
foremost in consumer's minds. In yet another geography, the speed
of acquisition of liquid insults may be foremost in consumer's
minds. In yet another geography, the amount of masking provided by
a topsheet may be foremost in consumer's minds.
[0005] It would be beneficial for a nonwoven and/or film web to
address one or more of the above concerns and allow for the
flexibility of addressing multiple of the above concerns. It would
also be beneficial to have a process which facilitated the
production of nonwoven and/or film webs capable of addressing one
or more of the above concerns and to provide a process providing
the flexibility to address multiple of the above concerns.
SUMMARY OF THE INVENTION
[0006] Disclosed herein are material webs which can be used in
absorbent articles including disposable absorbent articles. Some
exemplary uses include a topsheet or a backsheet of a diaper or
feminine pad or as an overwrap for a tampon. Some additional uses
are discussed herein. The material webs of the present invention,
when utilized as a topsheet of a feminine hygiene article, can
provide a soft feel to the user and can provide quick acquisition
of menses/urine insults. Other benefits and configurations are
discussed hereinafter. The material webs of the present invention
may be heated treated to create discrete melt additive bloom areas.
In other forms, the material webs of the present invention may be
heated treated across the entirety of the web to encourage melt
additive blooming across the entirety of the web. Still in other
forms, the addition of nucleating agents can facilitate blooming of
melt additive either across the entirety of a web or increase
blooming in melt additive bloom areas. Additional benefits are
described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] While the specification concludes with claims particularly
pointing out and distinctly claiming the subject matter of the
present invention, it is believed that the invention can be more
readily understood from the following description taken in
connection with the accompanying drawings, in which:
[0008] FIG. 1 is a schematic representation of a cross section of a
material web of the present invention.
[0009] FIG. 2 is a schematic representation of a generalized
process for making the material webs of the present invention.
[0010] FIG. 3A is a schematic representation of an exemplary
process for producing the material webs of the present
disclosure.
[0011] FIG. 3B is a perspective view of a web weakening arrangement
of FIG. 3A in accordance with the present disclosure.
[0012] FIG. 3C is a perspective view of an incremental stretching
system of the process of FIG. 3A in accordance with the present
disclosure.
[0013] FIG. 3D is an enlarged view showing the details of teeth of
the incremental stretching system of FIG. 3C in accordance with the
present disclosure.
[0014] FIG. 3E is a schematic illustration of a weakened precursor
material in accordance with the present disclosure.
[0015] FIG. 3F is a schematic illustration of an exemplary material
web in accordance with the present disclosure.
[0016] FIG. 3G is a cross-sectional view of the material web of
FIG. 3F along line 3G-3G.
[0017] FIG. 4A is a schematic representation of an exemplary
process for producing material webs of the present disclosure.
[0018] FIG. 4B is a cross-sectional view of a disposable absorbent
article in accordance with the present disclosure.
[0019] FIG. 5A is a schematic representation of an exemplary
process for producing material webs of the present disclosure.
[0020] FIGS. 5B-5J are schematic representations of tufts on
material webs of the present invention.
[0021] FIGS. 6A-6D are schematic representations of an apparatus
capable of producing nested tufts on material webs in accordance
with the present disclosure.
[0022] FIG. 6E is a plan view photomicrograph showing one side of a
material web having three-dimensional discontinuity formed therein
in accordance with the present disclosure.
[0023] FIG. 6F is a plan view photomicrograph showing the other
side of the material web of FIG. 6E, with the openings.
[0024] FIG. 6G is a perspective view of a nested tuft in a two
layer material web in accordance with the present disclosure.
[0025] FIG. 6H is a schematic view of a nested tuft in accordance
with the present disclosure.
[0026] FIG. 6I is a cross-sectional view taken along a transverse
axis of a nested tuft in accordance with the present
disclosure.
[0027] FIG. 6J is a cross-sectional view taken along a transverse
axis of a nested tuft in accordance with the present
disclosure.
[0028] FIG. 6K is a cross-sectional view taken along a transverse
axis of a nested tuft in accordance with the present
disclosure.
[0029] FIG. 6L is a cross-sectional view taken along a transverse
axis of a nested tuft in accordance with the present
disclosure.
[0030] FIG. 6M is a cross-sectional view taken along a transverse
axis of a nested tuft in accordance with the present
disclosure.
[0031] FIG. 6N is a cross-sectional view taken along a transverse
axis of a nested tuft in accordance with the present
disclosure.
[0032] FIG. 6O is a cross-sectional view taken along a transverse
axis of a nested tuft in accordance with the present
disclosure.
[0033] FIG. 6P is a cross-sectional view taken along a transverse
axis of another nested tuft in accordance with the present
disclosure.
[0034] FIG. 7A is a schematic representation of an exemplary
process for producing the material webs of the present
disclosure.
[0035] FIGS. 7B-7E are cross-sectional views showing a variety of
material webs comprising corrugations in accordance with the
present disclosure.
[0036] FIGS. 8A-8B are schematic representations of an exemplary
process for producing the material webs of the present
disclosure.
[0037] FIG. 8C is a cross-sectional view showing a material web in
accordance with the present disclosure.
[0038] FIG. 9A is a schematic side view of an exemplary process for
forming the material web which includes an additional roll for tip
bonding discontinuities in the material web.
[0039] FIG. 9B is a schematic cross-sectional view of a tip bonded
discontinuity (shown oriented downward) made by the apparatus shown
in FIG. 9A.
[0040] FIG. 10 is a schematic side view of an exemplary process for
forming the material web which includes an additional roll for base
bonding the material web.
[0041] FIG. 11A is a plan view of an exemplary base bonded material
web by the apparatus shown in FIG. 10 (shown with the base opening
oriented upward).
[0042] FIG. 11B is a schematic cross-sectional view of the base
bonded material web in FIG. 11A taken along line 11B-11B.
[0043] FIG. 12 is a plan view of another exemplary based bonded
material web by the apparatus shown in FIG. 10.
[0044] FIG. 13A is an enlarged perspective view of a portion of an
exemplary roll having a plurality of discrete bonding elements on
its surface.
[0045] FIG. 13B is an enlarged perspective view of a portion of an
exemplary roll having continuous bonding elements on its
surface.
[0046] FIG. 13C is a plan view of a portion of the surface of an
exemplary bonding roll with a plurality of discrete bonding
elements thereon.
[0047] FIG. 14 is a schematic side view of an exemplary process for
deforming the material web which includes additional rolls for tip
bonding and base bonding the material web.
[0048] FIG. 15 is a schematic side view of an exemplary process for
deforming the material web and providing corrugations therein.
[0049] FIG. 16 is an isometric view of an exemplary material web
derived from the process of FIG. 15.
[0050] FIG. 17 is a top view of a feminine hygiene article, i.e.
sanitary napkin, constructed in accordance with the present
disclosure.
[0051] FIG. 18 is a top view of an absorbent article with some
layers partially removed in accordance with the present
disclosure.
[0052] FIG. 19 is a cross-sectional view of the absorbent article
taken about line 19-19 of FIG. 18 in accordance with the present
disclosure.
[0053] FIG. 20 is a view of the absorbent article of FIG. 19 where
the absorbent article has been at least partially loaded with fluid
in accordance with the present disclosure.
[0054] FIG. 21 is an isometric view of an exemplary process for
manipulating the material web of the present disclosure.
[0055] FIG. 22A is an isometric view of an exemplary process for
manipulating the material web of the present disclosure.
[0056] FIG. 22B is a close up view of a pair of rolls shown in FIG.
22A.
[0057] FIG. 22C is a close up view showing an exemplary
configuration of one of the rolls shown in FIG. 22A.
[0058] FIG. 22D is a close up view showing an exemplary
configuration of the other of the rolls shown in FIG. 22A.
[0059] FIG. 23 is a top view of a 25 gsm polyethylene film web
(film is stretched/flattened out to show high and low basis weight
regions).
[0060] FIG. 24 is a top view of a 60 gsm polypropylene nonwoven web
(nonwoven is stretched/flattened out to show high and low basis
weight regions).
[0061] FIG. 25 is a cross-section view of the web shown in FIG.
24.
[0062] FIG. 26 is side perspective view of another nonwoven
web.
[0063] FIG. 27 is a top perspective view of another nonwoven
web.
[0064] FIG. 28A is an SEM image showing apertures, calendar bond
sites and fusion bond sites in a material web.
[0065] FIG. 28B is an SEM image of the fusion bond sites from FIG.
28A.
[0066] FIGS. 28C and 28D are SEM images of the apertures/melt lip
of FIG. 28A, FIGS. 28C and 28D being at 500 times and 1500 times
magnification, respectively.
[0067] FIGS. 29A and 29B are SEM images of an exemplary material
web which show melt additive bloom areas, FIGS. 29A and 29B being
at 500 times and 1500 times magnification, respectively.
[0068] FIG. 30A is an isometric view showing an apparatus for
creating corrugations in a material web of the present
disclosure.
[0069] FIG. 30B is an isometric view showing an exemplary material
web with corrugations in accordance with the present
disclosure.
[0070] FIG. 30C is a close up view of a corrugation of the material
web of FIG. 30B.
[0071] FIGS. 31A-34B are photomicrographs depicting exemplary water
droplets on fibers for the SEM contact angle measurement method
disclosed herein.
DETAILED DESCRIPTION OF THE INVENTION
[0072] As used herein "disposable absorbent article" or "absorbent
article" shall be used in reference to articles such as diapers,
training pants, diaper pants, refastenable pants, adult
incontinence pads, adult incontinence pants, feminine hygiene pads,
tampons, and pessary devices.
[0073] As used herein "hydrophilic" and "hydrophobic" have meanings
well established in the art with respect to the contact angle of a
referenced liquid on the surface of a material. Thus, a material
having a liquid contact angle of greater than about 90 degrees is
considered hydrophobic, and a material having a liquid contact
angle of less than about 90 degrees is considered hydrophilic.
Compositions which are hydrophobic, will increase the contact angle
of a referenced liquid on the surface of a material while
compositions which are hydrophilic will decrease the contact angle
of a referenced liquid on the surface of a material.
Notwithstanding the foregoing, reference to relative hydrophobicity
or hydrophilicity between material(s) and/or composition(s) does
not imply that the material or composition are hydrophobic or
hydrophilic. For example, a composition may be more hydrophobic
than a material. In such a case neither the composition nor the
material may be hydrophobic; however, the contact angle of water
droplets on the composition is greater than that of water droplets
on the material. As another example, a composition may be more
hydrophilic than a material. In such a case, neither the
composition nor the material may be hydrophilic; however, the
contact angle with respect to water droplets exhibited by the
composition may be less than that exhibited by the material. In
general, materials which demonstrate a high surface energy may be
considered to be more hydrophilic than materials which have a low
surface energy.
[0074] As used herein, "spunbond filaments" refers to small
diameter filaments which are formed by extruding molten
thermoplastic material as filaments from a plurality of fine
capillaries of a spinneret with the diameter of the extruded
filaments then being rapidly reduced. Spunbond filaments are
generally not tacky when they are deposited on a collecting
surface. Spunbond filaments are generally continuous and have
average diameters (from a sample of at least 10) larger than 7
microns, and more particularly, between about 8 and 40 microns.
[0075] The term "filament" refers to any type of artificial
continuous strand produced through a spinning process, a
meltblowing process, a melt fibrillation or film fibrillation
process, or an electrospinning production process, or any other
suitable process to make filaments. The term "continuous" within
the context of filaments are distinguishable from staple length
fibers in that staple length fibers are cut to a specific target
length. In contrast, "continuous filaments" are not cut to a
predetermined length, instead, they can break at random lengths but
are usually much longer than staple length fibers.
[0076] By "substantially randomly oriented" it is meant that, due
to processing conditions of a nonwoven web, there may be a higher
amount of filaments oriented in the machine direction (MD) than the
cross direction (CD), or vice-versa.
[0077] The material webs of the present invention may comprise a
film, a nonwoven, or a laminate created therefrom, e.g. a
film/nonwoven laminate, a film/film laminate, a nonwoven/nonwoven
laminate. Additionally, the material webs of the present invention
may comprise any suitable nonwoven and/or any suitable film. Some
exemplary nonwovens and films are discussed in additional detail in
the section entitled, "Precursor Material." The material webs of
the present invention are suitable for use in disposable absorbent
articles.
[0078] Referring to FIG. 1, material webs 100 of the present
invention comprises a first surface 20 and an opposing second
surface 30. The material webs 100 of the present invention have a
machine direction (MD) (perpendicular to the plane of the sheet
showing FIG. 1), a cross machine direction (CD), and the
Z-direction, as is commonly known in the art of web
manufacture.
[0079] The material web 100 of the present invention comprises a
constituent composition. The constituent composition comprises a
thermoplastic polymeric material and a melt additive. For example,
in the case of nonwoven materials, the fibers or filaments of the
material web 100 may comprise a hydrophobic melt additive, a
hydrophilic melt additive, or a softness melt additive. Suitable
melt additives are discussed hereafter.
[0080] The melt additive may be homogeneously mixed with the
thermoplastic polymeric material. In the case of bi-component or
multi-component fibers or filaments, the melt additive may
homogeneously mixed with a component of the bi-component or
multi-component fiber or filament but not necessarily across the
entirety of the fiber or filament. For example, a fiber or filament
having a core-sheath configuration may comprise a melt additive
homogeneously mixed with the thermoplastic polymeric material of
the sheath, while the core does not comprise the melt additive of
the sheath. Or, the core may comprise the melt additive of the
sheath, but in a different amount than that of the sheath.
[0081] In some forms of the present invention, processing of the
web as described herein can create discrete melt bloom areas, e.g.
discrete areas with lower surface energy, discrete areas with
higher surface energy, discrete soft areas, areas with higher or
lower coefficient of friction, etc. The inventors have surprisingly
found that the application of thermal energy to the material web
100, can facilitate the blooming of the melt additive to the
surface of the material web. For example, the application of
localized thermal energy to the material web 100 can promote the
creation of discrete melt additive bloom areas on the material web
100, e.g. on the first surface 20 and/or second surface 30. As
such, a material web 100, despite having a homogenous mixture of
polymer material and melt additive, can have discrete areas of
higher or lower surface energy, higher or lower coefficient of
friction, or softness.
[0082] "Discrete" as used herein does not mean that the "discrete"
melt additive bloom areas must be completely isolated from one
another. Rather, where thermal energy is applied in localized
areas, melt additive blooming will be promoted. As such, the melt
additive bloom areas corresponding to the localized thermal energy
areas should have more melt additive that blooms to the surface of
the material in those localized areas than those without localized
application of thermal energy. In some cases--where the melt
additive forms fibrils or some other topographical structure at the
surface of the filament--the enhanced blooming may be seen via SEM
in that there may be a stark difference between fibril growth on
the material web in one portion versus another. The stark
difference in fibril growth can be a sign of localized heat
treatment. Or, one of the other methods described herein may
determine whether melt additive bloom areas are localized as
opposed to being provided across the entirety of the material
web.
[0083] In general, discrete melt bloom areas versus adjacent
non-thermally treated areas exhibit a migration coefficient which
is two times that of a non-thermally treated area of a material
web. Depending on the thermal conductance of the thermoplastic
polymeric material, the localized application of thermal energy may
create heat affected zones which also encourages blooming. So when
measuring, care should be taken to ensure that a centralized
location of expected thermal energy application should be
analyzed.
[0084] Still referring to FIG. 1, the resulting material webs 100
of the present invention may then comprise varying property zones
in a variety of predetermined patterns along the MD and/or CD. For
example, selected portions of a hydrophobic web can be rendered
hydrophilic. As another example, selected portions of a hydrophilic
web can be rendered hydrophobic. Still as another example, selected
portions of a material web can be made softer via softness melt
additive selective blooming. Additional examples are provided
herein.
[0085] As another example, thermal energy can be applied to the
entirety of the material web 100 to facilitate the melt additive
blooming across the first surface and/or second surface of the
material web 100. This can provide the ability to raise or lower
the surface energy of the material web 100 where normal processing,
e.g. coating, would not be feasible. For example, where the
material web 100 comprises multiple strata (discussed hereafter),
post treatment of the material web 100 may impact the entirety of
the material web 100 rather than a desired stratum which may not be
desirable.
[0086] So, the amount of melt additive which blooms in the material
web can increase with the application of heat. Accordingly, the
material webs may be rendered more hydrophobic, more hydrophilic,
or softer than what would otherwise be the case sans the heat
treatment of the material web. This allows for much versatility of
the use of the material web. For example, a material web with a
hydrophobic melt additive may be processed into a
liquid-impermeable barrier material. However, such material may
also be subsequently processed into, a liquid-permeable material
(with the provision of apertures or appropriate basis weight
selection), a soft feeling material, etc., depending, in part, on
the thermal treatment applied.
[0087] Notwithstanding the potential drawbacks of topically applied
chemistries, the material webs of the present invention may be
combined/laminated with other webs which comprise topically applied
chemistries. As noted, the topically applied chemistry of the other
webs should occur prior to the combination with the material web to
minimize the possibility of the topically applied chemistry from
impacting the material web.
Material Web--Processing, in General
[0088] There are many methods by which the material web 100 of the
present invention may be provided with discrete melt additive bloom
areas. Similarly, there are a myriad of methods by which the
material web 100 of the present invention may be provided with melt
additive blooming across its entirety. Some specific
examples--regarding discrete melt additive bloom area creation--are
provided with regard to FIGS. 3A-16, 21, 22A-22D, and 30A-30C. But,
a general process description for the formation of both discrete
melt additive bloom areas and melt additive blooming across the
entirety of the material web 100 of the present invention is
provided with regard to FIG. 2.
[0089] As shown in FIG. 2, a precursor material 102 may be provided
to a first unit operation 140. In some forms, the first unit
operation 140 can manipulate the precursor material 102 to form the
material web 100. In some forms, the first unit operation 140 can
provide discontinuities in the precursor material 102 thereby
forming the material web 100. Discontinuities are disruptions to
the planar surface--either the first surface 20 and/or the second
surface 30 (shown in FIG. 1). Some exemplary discontinuities
include apertures, embossments, tunnel tufts, filled tufts, nested
tufts, ridges, grooves and corrugations. The discontinuities are
discussed in additional detail hereafter. And, as noted previously,
the material webs 100 of the present invention comprise a melt
additive. Accordingly, the precursor materials 102 of the present
invention comprise the melt additive of the material web 100.
[0090] In some forms, the discontinuities may extend away from the
first surface 20 or the second surface 30 in a positive Z-direction
or negative Z-direction. In such forms, the discontinuities may
comprise a distal end which is superjacent to the first surface or
subjacent to the second surface, sidewalls extending from the
distal end toward the first surface or second surface, and, in some
specific forms, a base disposed between the sidewalls and the first
surface or second surface. Discontinuities are discussed in
additional detail hereafter.
[0091] The first unit operation 140, in some forms of the present
invention, may provide sufficient thermal energy in a plurality of
discrete locations on the precursor material 102 to provide the
material web 100 with a plurality of discrete melt additive bloom
areas sans the formation of discontinuities. The discrete melt
additive bloom areas correspond with the discrete locations of
applied thermal energy. In some forms, at least a portion of the
plurality of melt additive bloom areas may be joined together to
form a pattern. Examples of melt additive bloom areas and their
formation are discussed hereafter. In some forms, as noted above,
the first unit operation 140 may provide sufficient thermal energy
to the entirety of the material web 100 to increase the melt
additive bloom areas for the entire material web 100.
[0092] The precursor material 102, which as shown in FIG. 2
subsequently becomes the material web 100, may be one or more
nonwoven materials (same or different), one or more films (same or
different), a combination of one or more nonwoven materials and one
or more films, or any other suitable materials or combinations
thereof. The precursor material 102 may be purchased from a
supplier and shipped to where the material webs 100 are being
formed, or the precursor material 102 may be subjected to the first
unit operation 140 by the manufacturer of the precursor web.
[0093] The precursor material 102 may be extensible, elastic, or
non-elastic. Further, the precursor material 102 may be a single
layer material or a multilayer material. For example, the precursor
material 102 may be joined to a polymeric film to form a laminate.
As another example, the precursor film 102 may comprise two or more
layers of film, two or more layers of nonwoven material, or
combinations thereof.
[0094] Additionally, forms of the present invention are
contemplated where the precursor material 102 comprises a nonwoven
web composite comprising multiple strata. A nonwoven stratum may
comprise spunbond, staple, or fine fibers, e.g. meltblown or
nanofibers. For example, in some forms, a first spinbeam may
deposit a first plurality of spunbond filaments onto a belt thereby
forming a first nonwoven stratum. A second spinbeam may deposit a
second plurality of spunbond filaments onto the belt over the top
of the first plurality of spunbond filaments. The second plurality
of spunbond filaments form a second nonwoven stratum. Additional
forms of the present invention are contemplated where additional
spinbeams are provided to provide additional spunbond
filaments/nonwoven strata. As another example, a first nonwoven
stratum may comprise a plurality of staple fibers upon which a
plurality of spunbond filaments are deposited. Additionally, the
precursor webs 102/material webs 100 of the present invention may
comprise a third stratum a fourth stratum and so on. And, the
strata of the precursor web 102/material web 100 may be configured
such that at least two of the strata are different. As such,
precursor web 102/material web 100 may be one layer comprising
multiple strata as described herein and/or may comprise multiple
layers in addition to multiple strata.
[0095] The precursor material 102 may be provided as discrete webs,
e.g. sheets, patches, etc. of material for batch processing. For
commercial processing, however, the precursor material 102 may be
supplied as roll stock, and, as such it can be considered as having
a finite width and an infinite length. In this context, the length
is measured in the machine direction (MD). Likewise, the width is
measured in the cross machine direction (CD).
Zoned Application of Thermal Energy
[0096] As noted previously, in some forms, thermal energy may be
applied to the web during the formation of discontinuities within
the precursor material 102. In such forms, localized areas of the
precursor material 102 may be heated which promotes discrete melt
bloom areas which correspond to the localized heat application.
Exemplary processes are discussed below.
Apertures
[0097] Referring to FIG. 3A, in one specific example, the first
unit operation 140 may comprise a process for forming apertures in
the precursor web 102. In some forms of the present invention, the
first unit operation 140 may comprise a weakening roller
arrangement 108 and an incremental stretching system 132. As shown,
the precursor material 102 may be unwound from a supply roll 104
and travel in a direction indicated by the arrow associated
therewith as the supply roll 104 rotates in the direction indicated
by the arrow associated therewith. The precursor material 102 can
pass through a nip 106 of the weakening roller (or overbonding)
arrangement 108 formed by rollers 110 and 112, thereby weakening
the precursor material 102 at a plurality of discrete locations.
The weakened precursor material 102 has a pattern of overbonds, or
densified and weakened areas, after passing through the nip 106. At
least some of, or all of, these overbonds are used to form
apertures in the material web 100. Therefore, the overbonds can
correlate generally to the patterns of apertures created in the
material web 100.
[0098] Referring to FIGS. 3A and 3B, the weakening roller
arrangement 108 may comprises a patterned calendar roller 110 and a
smooth anvil roller 112. One or both of the patterned calendar
roller 110 and the smooth anvil roller 112 may be heated and the
pressure between the two rollers may be adjusted to provide the
desired temperature, if any, and pressure to concurrently weaken
and melt-stabilize (i.e., overbond) the precursor material 102 at a
plurality of locations 202. As will be discussed in further detail
below, after the precursor material 102 passes through the
weakening roller arrangement 108, the weakened precursor material
102 may be stretched in the CD, or generally in the CD, by a cross
directional tensioning force to at least partially, or fully,
rupture the plurality of weakened, melt stabilized locations
202.
[0099] The patterned calendar roller 110 is configured to have a
cylindrical surface 114, and a plurality of protuberances or
pattern elements 116 which extend outwardly from the cylindrical
surface 114. The pattern elements 116 are illustrated as a
simplified example of a patterned calendar roller 110, but more
detailed patterned calendar rollers are contemplated and will be
discussed hereafter. The protuberances 116 may be disposed in a
predetermined pattern with each of the protuberances 116 being
configured and disposed to precipitate a weakened, melt-stabilized
location in the weakened precursor material 102 to affect a
predetermined pattern of weakened, melt-stabilized locations 202.
The protuberances 116 may have a one-to-one correspondence to the
pattern of melt stabilized locations in the weakened precursor
material 102. As shown in FIG. 3B, the patterned calendar roller
110 may have a repeating pattern of the protuberances 116 which
extend about the entire circumference of surface 114.
Alternatively, the protuberances 116 may extend around a portion,
or portions of the circumference of the surface 114. Also, a single
patterned calendar roller may have a plurality of patterns in
various zones (i.e., first zone, first pattern, second zone, second
pattern, etc.). The protuberances 116 may extend radially outwardly
from surface 114 and have distal end surfaces 117. The anvil roller
112 may be a smooth surfaced, circular cylinder of steel, rubber or
other material. The anvil roller 112 and the patterned calendar
roller 110 may be switched in position (i.e., anvil on top) and
achieve the same result.
[0100] Referring back to FIG. 3A, from the weakening roller
arrangement 108, the weakened precursor material 102 passes through
a nip 130 formed by the incremental stretching system 132 employing
opposed pressure applicators having three-dimensional surfaces
which at least to a degree may be complementary to one another.
[0101] Referring now to FIG. 3C, there is shown a fragmentary
enlarged view of the incremental stretching system 132 comprising
two incremental stretching rollers 134 and 136. The incremental
stretching roller 134 may comprise a plurality of teeth 160 and
corresponding grooves 161 which may about the entire circumference
of roller 134. The incremental stretching roller 136 may comprise a
plurality of teeth 162 and a plurality of corresponding grooves
163. The teeth 160 on the roller 134 may intermesh with or engage
the grooves 163 on the roller 136 while the teeth 162 on the roller
136 may intermesh with or engage the grooves 161 on the roller 134.
As the precursor material 102 having weakened, melt-stabilized
locations 202 passes through the incremental stretching system 132
the precursor material 102 is subjected to tensioning in the CD
causing the material 102 to be extended (or activated) in the CD,
or generally in the CD. Additionally the precursor material 102 may
be tensioned in the MD, or generally in the MD. The CD tensioning
force placed on the material 102 is adjusted such that it causes
the weakened, melt-stabilized locations 202 to at least partially,
or fully, rupture thereby creating a plurality of partially formed,
or formed apertures 204 coincident with the weakened
melt-stabilized locations 202 in the precursor material 102. The
melt-stabilized locations 202 form melt lips defining the periphery
of the apertures 204. However, the bonds of the precursor material
102 (in the non-overbonded areas) are strong enough such that many
do not rupture during tensioning, thereby maintaining the precursor
material 102 in a coherent condition even as the weakened,
melt-stabilized locations rupture. However, it may be desirable to
have some of the bonds rupture during tensioning.
[0102] Referring to FIG. 3D, a more detailed view of the teeth 160
and 162 and the grooves 161 and 163 on the rollers 134 and 136 is
illustrated. The term "pitch" refers to the distance between the
apexes of adjacent teeth. The pitch may be between about 0.02
inches to about 0.30 inches (about 0.51 mm to about 7.62 mm) or
preferably may be between about 0.05 inches and about 0.15 inches
(about 1.27 mm to about 3.81 mm), specifically reciting all 0.001
inch increments within the above-specified ranges and all ranges
formed therein or thereby. The height (or depth) of the teeth is
measured from the base of the tooth to the apex of the tooth, and
may or may not be equal for all teeth. The height of the teeth may
be between about 0.010 inches (about 0.254 mm) and about 0.90
inches (about 22.9 mm) or preferably may be between about 0.025
inches (about 0.635 mm) and about 0.50 inches (about 12.7 mm),
specifically reciting all 0.01 inch increments within the
above-specified ranges and all ranges formed therein or thereby.
The teeth 160 in one roll may be offset by about one-half of the
pitch from the teeth 162 in the other roll, such that the teeth of
one roll (e.g., teeth 160) mesh in the valley (e.g., groove 163)
between teeth in the mating roll. The offset permits intermeshing
of the two rolls when the rolls are "engaged" or in an
intermeshing, operative position relative to one another. The teeth
of the respective rolls may only be partially intermeshing in some
instances. The degree to which the teeth on the opposing rolls
intermesh is referred to herein as the "depth of engagement" or
"DOE" of the teeth. The DOE may be constant or not constant. As
shown in FIG. 3D, the DOE, indicated as "E", is the distance
between a position designated by plane P1 where the apexes of the
teeth on the respective rolls are in the same plane (0% engagement)
to a position designated by plane P2 where the apexes of the teeth
of one roll extend inward beyond the plane P1 toward the groove on
the opposing roll. The optimum or effective DOE for particular
material webs may be dependent upon the height and the pitch of the
teeth and/or the structure of the material. Some example DOEs may
in the range of about 0.01 inches to about 0.5 inches, about 0.03
inches to about 0.2 inches, about 0.04 inches to about 0.08 inches,
about 0.05 inches, or about 0.06 inches, specifically reciting all
0.001 inch increments within the above-specified ranges and all
ranges formed therein or thereby.
[0103] Referring back to FIG. 3A, after the weakened precursor
material 102 passes through the incremental web stretching
apparatus 132, the web 102 may be advanced to and at least
partially around a cross machine directional tensioning apparatus
132' (described further in U.S. patent application Ser. No.
14/933,001). The cross machine directional tensioning apparatus
132' may be offset from the main processing line by running the web
partially around two idlers 133 and 135 or stationary bars, for
example. In other instances, the cross machine tensioning apparatus
132' may be positioned in line with the main processing line.
[0104] If desired, the incremental stretching step or the cross
machine directional stretching step described herein may be
performed at elevated temperatures. For example, the weakened
precursor material 102 and/or the rolls may be heated. Utilizing
heat in the stretching step may serve to soften the material, and
may aid in extending the fibers without breaking.
[0105] Still referring to FIG. 3A, the material web 100 may be
taken up on wind-up roll 180 and stored. Alternatively, the
material web 100 may be fed directly to a production line where it
is used to form a portion of an absorbent article, or other
consumer product. This particular aperturing process is further
described in in U.S. Pat. Nos. 5,658,639; 5,628,097; 5,916,661;
7,917,985; and U.S. Patent Application Publication No. 2003/0021951
and U.S. patent application Ser. Nos. 14/933,028; 14/933,017; and
Ser. No. 14/933,001.
[0106] It is important to note that the overbonding step
illustrated in FIGS. 3A and 3B could be performed by the material
supplier and then the material may be shipped to a consumer product
manufacturer for the incremental stretching 132. In such forms, the
rolls 134 and 136 of the incremental web stretching apparatus may
be heated to create discrete areas on the web. Additionally, the
overbonding step may be used in the material web production process
to form overbonds, which may be in addition to, or in lieu of,
primary bonds formed in the material web production process.
Alternatively, the material supplier may fully perform the steps
illustrated in FIG. 3A and then the material web 100 may be shipped
to the manufacturer. The manufacturer may also perform all of the
steps in FIG. 3A after obtaining a precursor material 102 from a
manufacturer.
[0107] Referring to FIGS. 3A, 3B and 3E, as noted previously, the
precursor web 102 of the present invention comprises the melt
additive in the material web 100. And, with the application of heat
with the weakening roller arrangement 108, particularly with heat
being applied by the pattern elements 116 of the patterned calendar
roller 110, heat is applied to the precursor material 102 in a
plurality of discrete locations on the precursor web 102, i.e. the
melt-stabilized areas 202. It is believed that with the application
of heat by the pattern elements 116 to the melt-stabilized areas
202, that the melt additive may bloom to the surface of the
precursor material 102 in the melt-stabilized areas 202 and about a
periphery (or portions thereof) of the melt-stabilized areas 202.
An example is shown in FIG. 3E where the melt additive bloom area
320 is depicted in only one melt-stabilized area 202. The melt
additive bloom areas 320 may occur in all, substantially all, or a
portion of the melt-stabilized areas 202 assuming that the heat
applied by the patterned calendar roller 110 limited to a specific
pattern of the pattern elements 116. For those areas of the
precursor material 102 that were not exposed to heat via the
weakening roller arrangement, the melt additive may stay locked in
the polymer matrix of the material web for a long period of time.
This will be discussed in additional detail hereafter.
[0108] In some forms, the calendar roller 110 may be heated such
that the pattern elements 116 apply thermal energy to the precursor
material 102. In such forms, the surface 114 of the calendar roller
110 may comprise an insulating material such that any thermal
energy provided by the surface 114 to the precursor web is
reduced/minimized. Forms of the present invention are contemplated
where a portion of the pattern elements 116 are insulated. In such
forms, a plurality of melt additive bloom areas 320 may be provided
to the weakened precursor web 102 in a pattern. Any suitable
insulating material may be utilized. Some examples include ceramics
and/or rubber based compositions. Thermal insulators are generally
known in the art.
[0109] For those forms of the present invention where the melt
additive is hydrophilic, the heat applied by the pattern elements
116 during the formation of the melt-stabilized areas 202 can cause
the hydrophilic melt additive to bloom on the melt-stabilized areas
202 and portions of the weakened precursor web 102 in close
proximity to the melt-stabilized areas 202. However, for the
remainder of the weakened precursor material 102, the hydrophilic
melt additive may be locked in the polymer matrix of the precursor
material 102.
[0110] Referring back to FIG. 3B, additional forms of the present
invention are contemplated where a portion of the distal end 117 of
the pattern elements 116 are insulated such that only a portion of
each of the melt-stabilized area 202 is heated. So for example,
where a distal end 117 comprises an area of 5 mm.sup.2, only 50
percent of the distal end 117 may provide sufficient thermal energy
to the precursor web 102 to provide a melt additive bloom area 320.
In such forms, at least a portion of the distal ends 117 may be
insulated such that thermal energy supplied to the precursor web
102 via the insulated portions is reduced. Additionally, in such
forms, the resultant melt-stabilized area 202 may comprise a melt
additive bloom area 320 which comprised about 50 percent of the
melt-stabilized area 202. In some forms, less than about 80
percent, less than about 70 percent, less than about 60 percent,
less than about 50 percent, less than about 40 percent, less than
about 30 percent, less than about 20 percent, less than about 10
percent of the melt-stabilized areas 202 area may comprise a melt
additive bloom area, specifically including all values within these
ranges and any ranges created thereby. Referring to FIG. 3F,
subsequent to the incremental stretching step, the material web 100
comprising a plurality of apertures 204 is shown. With the above
example in mind (hydrophilic melt additive) the apertures 204 can
be hydrophilic even where the material web 100 comprises
hydrophobic material, e.g. polypropylene, polyethylene. Such
constructions can be beneficial, particularly in the absorbent
article context when the material web 100 is utilized as a
topsheet. For example, the hydrophilic apertures 204 can provide
adequate acquisition time for liquid insults while reducing the
likelihood of liquid re-surfacing and contacting a user, e.g.
rewet, and minimizing retention of liquid within the fiber
matrix.
[0111] Regarding FIG. 3G, the melt additive bloom areas 320 may
comprise a first portion 320A disposed on the first surface 20.
Additionally, each of the melt additive bloom areas 320 may
comprise a second portion 320B which is disposed on melt lips of
the apertures 204. The size of the first portion 320A may be varied
depending upon the heat transfer characteristics of the composition
of the material web 100 and the amount of thermal energy
transferred to the precursor material 102 (shown in FIG. 3A) by the
patterned calendar roll 110 (shown in FIG. 3A). In some forms, the
first portion 320A may extend outboard in the MD and/or CD of the
sidewalls. In some forms, the first portion 320A may have an area
which is less than an Effective Aperture AREA of the apertures 204.
In some forms, the first portion 320A may have an area which is
about equal to the Effective Aperture AREA of the apertures 204. In
some forms, the first portion 320A may have an area which is
greater than the Effective Aperture AREA of the apertures 204.
Forms are contemplated where the second portion 320B comprises a
higher percentage of melt additive blooming than does the first
portion 320A. Depending on the insulation provided to the weakening
roller arrangement 108, forms of the present invention are
contemplated where the first portion 320A comprises a higher
percentage of melt additive blooming than does the second portion
320B.
[0112] Additionally, referring back to FIG. 3C, while forms of the
present invention are contemplated where rolls of the incremental
web stretching apparatus 132 are heated, such forms may provide the
material web 100 with the different properties. In such forms, the
melt additive bloom areas 320 may be provided as described above
with regard to FIG. 3G; however, melt additive bloom areas 320 may
additionally be provided as a plurality of stripes extending in the
MD direction extending between adjacent apertures 204. Such a
configuration for the material web 100--particularly when utilized
as a topsheet in a disposable absorbent article--while possibly
improving liquid acquisition time, may facilitate rewet
conditions.
[0113] The apertures 204 may be any suitable size. For example,
apertures 204 may have an Effective Aperture AREA in the range of
about 0.1 mm.sup.2 to about 15 mm.sup.2, about 0.3 mm.sup.2 to
about 14 mm.sup.2, about 0.4 mm.sup.2 to about 12 mm.sup.2, and
about 1.0 mm.sup.2 to about 5 mm.sup.2, specifically including all
0.05 mm.sup.2 increments within the specified ranges and all ranges
formed therein or thereby. All Effective Aperture Areas are
determined using the Aperture Test described herein. Effective
Aperture Area is discussed in further detail in U.S. patent
application Ser. Nos. 14/933,028; 14/933,017; and Ser. No.
14/933,001. For those forms of the present invention where the melt
additive bloom areas 320 comprise a hydrophilic composition,
acquisition speeds may be improved particularly where Effective
Aperture Areas are small. Smaller apertures may be more
aesthetically pleasing to users of absorbent articles; however, the
smaller apertures can have a negative impact on fluid acquisition
speed.
[0114] Additional processes for aperturing nonwoven webs are
described in U.S. Pat. Nos. 8,679,391 and 8,158,043, and U.S.
Patent Application Publication Nos. 2001/0024940 and 2012/0282436.
Other methods for aperturing nonwoven webs are provided in U.S.
Pat. Nos. 3,566,726; 4,634,440; and 4,780,352. Regardless of the
process utilized to create the apertures 204, the addition of
thermal energy can create the melt additive bloom areas as
discussed herein in localized areas where thermal energy is applied
to the precursor material 102 or the material web 100. In such
forms, referring back to FIG. 3A, a perforating roll may engage an
anvil roll. The perforating roll may have heated pins or rods which
can create apertures without the need for a subsequent stretching
step. The resultant melt bloom area 320 may be as described with
regard to FIG. 3G.
[0115] Additional forms of the present invention are contemplated
where the melt additive comprises a hydrophobic composition. In
such forms, referring to FIG. 3B, the cylindrical surface 114 may
be heated while the pattern elements 116 extending therefrom are
not. In such forms, melt additive blooms would be created in areas
of the material web 100 between the melt-stabilized areas 202 but
not in the melt-stabilized areas. Such configuration may be
beneficial where the material web 100 comprises a hydrophilic
material. Additionally, such configurations can help prevent rewet
conditions in an absorbent article where the material web 100 is
utilized as a topsheet of the absorbent article.
[0116] Additional forms of the present invention are contemplated
where the apertures are provided to the material web 100 in an
array and/or pattern or a plurality thereof. Such configurations
and processes are described in additional detail in U.S. patent
application Ser. Nos. 14/933,028; 14/933,017; and Ser. No.
14/933,001.
Embossments
[0117] Referring to FIG. 4A, in another specific example, the first
unit operation 140 (shown in FIG. 2) may comprise a process for
forming embossments in the material web 100. Referring to FIG. 4A,
the precursor material 102 may be subjected to an apparatus 400 for
providing embossments 420 to the material web 100.
[0118] The apparatus 400 may comprise a forming roll 402 comprising
a plurality of forming elements 416 and an anvil roll 404. The
forming elements 416 of the forming roll 402 may protrude outward
from a surface 414 of the forming roll 402. The anvil roll 404 may
comprise a smooth outer surface.
[0119] In contrast to fusion bond sites, discussed hereafter,
embossments 420 generally do not cause the fusion of the
constituent material of the material web 100 to adjacent materials.
Instead, embossments 420 tend to compress the material web 100.
Embossments 420 can provide an acquisition zone in an absorbent
article. For example, where the material web 100 forms a portion of
a topsheet of an absorbent article, the embossment 420 may not
readily receive a liquid insult. Instead, the embossment 420 may
act as a fluid highway which can distribute the insult to multiple
areas of an absorbent core in the absorbent article.
[0120] An exemplary cross section of the material web 100 in an
absorbent article 421 after embossing is shown in FIG. 4B. As
shown, the absorbent article 421 comprises the material web 100 as
a topsheet, a backsheet 455 and an absorbent core 465 disposed
between the backsheet 455 and the topsheet (material web 100). In
some forms, the material web 100 may comprise embossments 420. In
some forms, the material web 100 along with the absorbent core 465
may comprise embossments 420. In some forms, the material web 100
along with additional layers between topsheet and the absorbent
core 465, e.g. acquisition layers, distribution layers, secondary
topsheets, may comprise embossments 420.
[0121] Forms are contemplated where 100 percent of each of the
forming elements provides heat to the material web 100 and
optionally additional materials. In some forms, only portions of
the forming elements may provide thermal energy to the material web
100 and optionally other components.
[0122] With the application of thermal energy to the forming
elements 416 (shown in FIG. 4A), each of the embossments 420 may
comprise a melt additive bloom area 490. The melt additive bloom
areas 490 are exaggerated for ease of visualization. As shown, with
the application of thermal energy by the forming elements 416
(shown in FIG. 4A), the melt additive bloom areas 490 may be
provided in a distal end 454 of the embossment 420. Additionally,
the melt additive bloom areas 490 may be provided on sidewalls 456
of the embossments 420.
[0123] In some forms, the melt additive bloom area 490 may comprise
a hydrophobic composition. The compression which creates the
embossments 420 can inhibit fluid acquisition in the embossment
420. A hydrophobic composition in the distal end 454 of the
embossment 420 can assist in transporting liquid insults to
additional areas of the absorbent article. Additionally, the
hydrophobic composition can provide a cleaner look to the absorbent
article in the area of the embossment 420 since the hydrophobic
composition would discourage liquid insults from residing in the
embossment 420.
[0124] In contrast, forms of the present invention are contemplated
where the melt additive bloom areas 490 comprise a hydrophilic
composition. In such forms, the hydrophilic composition may
facilitate fluid acquisition by the embossments 420. It is worth
noting however, that in such forms, the level of compression in the
embossments 420 can offset the hydrophilic composition. For
example, where the embossments 420 are formed with high
compression, the embossments 420 have an increased density which
generally inhibits fluid acquisition. In contrast, embossments 420
derived from lighter compression can drive better interaction
between layers of the absorbent article 421 which can improve
liquid acquisition.
[0125] Embossments 420 may be used in conjunction with apertures
204 or may be utilized independently thereof. Any suitable
embossment pattern may be utilized in conjunction with the material
web 100 of the present invention. Some suitable examples of
embossment patterns are provided with regard to U.S. Pat. Nos.
6,170,393; 6,652,500; 7,056,404; 8,030,535; 8,492,609; 8,496,775;
and U.S. Patent Application Publication Nos. 2013/0281953; and
2014/0031779.
Tunnel Tufts/Filled Tufts
[0126] Referring to FIG. 5A, in another specific example, the first
unit operation 140 (shown in FIG. 2) may comprise an apparatus 500
for forming tufts in the material web 100. The apparatus 500
comprises a pair of intermeshing rolls 502 and 504, each rotating
about an axis A--the axes A being parallel and in the same plane.
Roll 502 comprises a plurality of ridges 506 and corresponding
grooves 508 which extend unbroken about the entire circumference of
roll 502.
[0127] Roll 504 is similar to roll 502, but rather than having
ridges that extend unbroken about the entire circumference, roll
504 comprises a plurality of rows of circumferentially-extending
ridges that have been modified to be rows of
circumferentially-spaced teeth 510 that extend in spaced
relationship about at least a portion of roll 504. The individual
rows of teeth 510 of roll 504 are separated by corresponding
grooves 512. In operation, rolls 502 and 504 intermesh such that
the ridges 506 of roll 502 extend into the grooves 512 of roll 504
and the teeth 510 of roll 504 extend into the grooves 508 of roll
502. A nip 516 is formed between the counter-rotating intermeshing
rolls 502 and 504. Both or either of rolls 502 and 504 can be
heated by means known in the art such as by using hot oil filled
rollers or electrically-heated rollers.
[0128] The apparatus 500 is shown in a configuration having one
patterned roll, e.g., roll 504, and one non-patterned grooved roll
502. However, in certain forms it may be preferable to use two
patterned rolls similar to roll 504 having either the same or
differing patterns, in the same or different corresponding regions
of the respective rolls. Such an apparatus can produce material
webs with tufts protruding from both sides of the material web
100.
[0129] Material webs 100 of the present invention can be made by
mechanically deforming the precursor material 102 that can be
described as generally planar and two dimensional prior to
processing by the apparatus shown in FIG. 5A. By "planar" and "two
dimensional" is meant simply that the webs start the process in a
generally flat condition relative to the finished material web 100
that has distinct, out-of-plane, Z-direction three-dimensionality
due to the formation of tufts 570. "Planar" and "two-dimensional"
are not meant to imply any particular flatness, smoothness or
dimensionality. The intermeshing rolls 502 and 504 can urge the
material of the material web 100 in the positive Z-direction or
negative Z-direction depending on whether roll 504 engages the
second surface 30 (shown in FIG. 1) or the first surface 20 (shown
in FIG. 1), respectively.
[0130] The process described with regard to FIG. 5A can provide for
a variety of tufts, e.g. tunnel tufts, filled tufts, outer tufts.
Each of these tufts is described in additional detail hereafter.
Tunnel tufts 570 are described with regard to FIGS. 5B-5E. For the
sake of clarity, the material web 100 depicted in FIGS. 5B-5E
comprises multiple layers, e.g. first layer 25 and second layer 35,
or multiple strata; however, forms of the present invention are
contemplated where the material web 100 comprises only a single
layer or a single strata.
[0131] The tunnel tuft 570 may be created when localized areas of
constituent material of the material web 100 are urged in the
positive Z-direction such that material of the material web 100 in
the localized area may be disposed superjacent to the first surface
20 of the material web 100. The disposition of the material web 100
in the localized areas may form the tunnel tuft 570. For such
forms, an opening 285 may be produced on the second surface 30 of
the material web 100 which corresponds to the tuft 570. And, as
shown in FIG. 5B, in some forms, the urging of the material web 100
in the localized areas may cause at least a portion of the first
layer 25 to break. In such forms, the tunnel tufts 570 may extend
through ends 545 of the first layer 25. However, as shown in FIG.
5C, the urging of the material of the material web 100 in the
localized areas can create an outer tuft 530. In some forms, the
outer tuft 530 may form a cap over the tunnel tuft 570.
[0132] In some forms, material webs 100 of the present invention
may comprise a plurality of tunnel tufts 570 for which there are no
corresponding outer tufts 530 and/or similarly may comprise a
plurality of tunnel tufts 570 each of which are disposed within a
corresponding outer tuft 530.
[0133] Additional arrangements of tunnel tufts 570 and outer tufts
530 are provided with respect to FIGS. 5D and 5E. As shown, the
tunnel tuft 270 and/or outer tuft 530 may extend beyond the second
surface 30 of the material web 100. However, instead being urged in
the positive Z-direction, urging of the material of the material
web 100 in the localized areas may be in the negative Z-direction.
And, similar to FIG. 5B, some of the material of the second layer
35 may break as shown in FIG. 5D or may form the outer tuft 530 as
shown in FIG. 5E.
[0134] FIGS. 5B-5F illustrate tunnel tufts 570 which may be formed
with nonwoven webs comprising extensible fibers. The tunnel tufts
570 and outer tufts 530 disclosed herein comprise a plurality of
looped filaments that are substantially aligned such that each of
the tunnel tufts 570 and outer tufts 530 have a distinct linear
orientation and a longitudinal axis L of the tuft, e.g. 570, 530.
By "aligned", it is meant that looped fibers are all generally
oriented such that, if viewed in plan view, each of the looped
fibers has a significant vector component parallel to a transverse
axis and can have a major vector component parallel to the
transverse axis. The transverse axis T is generally orthogonal to
longitudinal axis in the MD-CD plane and the longitudinal axis is
generally parallel to the MD.
[0135] Another characteristic of the tunnel tufts 570 and outer
tufts 530 shown in FIGS. 5B-5F--formed with extensible non-crimped
fibers--can be their generally open structure characterized by open
void area 533 defined interiorly of the tunnel tuft 570. The term
"void area" is not meant to refer to an area completely free of any
fibers. The void area 533 of tunnel tufts 570 may comprise a first
void space opening and a second void space opening. Rather, the
term is meant as a general description of the general appearance of
tunnel tuft 570. Therefore, it may be that in some tunnel tufts 570
a non-looped filaments or a plurality of loose non-looped filaments
may be present in the void area 533. By "open" void area is meant
that the two longitudinal ends of tunnel tuft 570 are generally
open and free of filaments, such that the tunnel tuft 570 can form
something like a "tunnel" structure in an uncompressed state, as
shown in FIGS. 5B-5F.
[0136] The extension and/or urging of the material of the material
web 100, as shown in FIGS. 5A-5F, can be accompanied by a general
reduction in filament cross sectional dimension (e.g., diameter for
round filaments) due to plastic deformation of the filaments and
Poisson's ratio effects.
[0137] Referring to FIGS. 5A-5E, as noted the intermeshing rolls
502 and 504 may be heated. For example, the circumferentially
spaced teeth 510 of roll 504 may be heated while the ridges 506 of
roll 502 are not. In such forms, the tunnel tufts 570 may further
comprise melt additive bloom areas 590 and/or 595 associated with
the second layer 35 and first layer 25, respectively. The melt
additive blooms 590 and 595 are exaggerated for ease of
explanation. The melt additive blooms are discussed further
hereafter. As shown, each of the tunnel tufts 570 and outer tufts
530 comprise a base 50, a distal end 554 spaced from the base 50
and sidewalls 556 between the base 50 and the distal end 554.
[0138] Referring specifically to FIG. 5B, forms where the material
web 100 comprises a first layer 25 and a second layer 35, the melt
additive bloom 590 may comprise a hydrophobic composition. As
shown, for those forms of the present invention where the material
web 100 comprises multiple layers or strata, the melt additive
bloom area 590 may be associated with the second layer 35 or second
strata. Forms of the present invention are contemplated where the
material web 100 comprise a first strata and a second strata, and
wherein the melt additive bloom area 590 is present on the tunnel
tuft 570 formed by the second strata. In such forms, the melt
additive bloom area 590 may comprise a hydrophobic composition. As
shown, with the application of thermal energy during the formation
of the tunnel tuft 570, the melt additive bloom area 590 may be
disposed on the distal end 554 of the tunnel tuft 570. In some
forms, the melt additive bloom area 590 may be disposed on at least
a portion of sidewalls 556 of the tunnel tuft 570. Where the
material web 100 is utilized as a topsheet, such forms can allow
for reduction in rewet while providing adequate liquid acquisition.
Additionally, in such forms, the melt additive bloom area 590 may
help with masking of liquid insults to a disposable absorbent
article.
[0139] Referring to FIG. 5C, for those forms of the present
invention comprising both outer tufts 530 and tunnel tufts 570, the
heated circumferentially spaced teeth 510 of roll 504 may
facilitate a melt additive bloom area 595 associated with the first
layer 25 or first strata and the melt additive bloom area 590
associated with the second layer 35. In such forms, the melt
additive bloom area 595 may comprise a hydrophobic composition and
the melt additive bloom area 590 may comprise a hydrophilic
composition. In some forms, the melt additive bloom area 590 and
the melt additive bloom area 595 may each comprise hydrophobic
compositions. As shown, the melt additive bloom area 595 may be
disposed on the distal end 554 of the outer tuft 530 and a portion
of sidewalls 556 of the outer tuft 530. Similarly, in such forms,
where the material web 100 is utilized as a topsheet of an
absorbent article, the above configuration can allow for sufficient
liquid acquisition time while reducing rewet. Such configurations
may additionally provide a benefit in masking liquid insults.
[0140] Referring specifically to FIG. 5D, for those forms of the
present invention comprising tunnel tufts 570 in the negative
Z-direction, the heated circumferentially spaced teeth 510 of roll
504 may facilitate the melt additive bloom area 590 associated with
the first layer 25 or first strata. In such forms, the melt
additive bloom area 590 may comprise a hydrophilic composition. As
shown, the melt additive area 590 may be configured as described
above with regard to FIG. 5B. Namely, the melt additive bloom area
590 may be disposed on the distal area 554 of the tunnel tuft 570
and on a portion of the sidewalls 556 of the tunnel tuft 570. In
such forms, where the material web 100 is utilized as a topsheet of
a disposable absorbent article, the melt additive bloom area 590
may comprise a hydrophilic composition which can improve the liquid
acquisition time of the absorbent article.
[0141] Referring to FIG. 5E, for the forms of the present invention
comprising both outer tufts 530 and tunnel tufts 570, the heated
circumferentially spaced teeth 510 of roll 504 may facilitate a
melt additive bloom area 595 associated with the second layer 25 or
second strata and the melt additive bloom area 590 associated with
the first layer 35 or first strata. In such forms, the melt
additive bloom area 595 may comprise a hydrophilic composition, and
the melt additive bloom area 590 may comprise a hydrophilic
composition. As shown, the melt additive bloom area 595 may be
disposed on the distal end 554 of the outer tuft 530 and a portion
of sidewalls 556 of the outer tuft 530. In such forms, the melt
additive bloom areas 590 and 595 can improve the liquid acquisition
time of topsheets of a disposable absorbent article.
[0142] Tunnel tufts 570 and/or outer tufts 530 can provide a
masking benefit for liquid insults in a disposable absorbent
article. Additionally, tunnel tufts 570 and/or outer tufts 530 can
provide a softness benefit as well. Tunnel tufts 570 and outer
tufts 530 are discussed in additional detail, including methods of
making, in U.S. Pat. Nos. 7,172,801; 7,838,099; 7,754,050;
7,682,686; 7,410,683; 7,507,459; 7,553,532; 7,718,243; 7,648,752;
7,732,657; 7,789,994; 8,728,049; and 8,153,226.
[0143] The tunnel tufts 570 and/or outer tufts 530 may be used in
conjunction with the apertures, and/or embossments. Or, the tunnel
tufts 570 and/or outer tufts 530 may be utilized independently
thereof.
[0144] In contrast to the tunnel tufts 570 shown in FIGS. 5A-5F,
material webs 100 of the present invention comprising crimped
filament spunbond nonwoven layer(s) or strata may form filled tufts
572 (shown in FIGS. 5G-5J). As shown, each of the filled tufts 572
and outer tufts 530 comprise a base 50, the distal end 554 spaced
from the base 50 and sidewalls 556 between the base and the distal
end 554. Referring specifically to FIG. 5G, forms where the
material web 100 comprises a first layer 25 and a second layer 35,
the melt additive bloom area 590 may comprise a hydrophobic
composition and be associated with the second layer 35 or second
strata. Forms of the present invention are contemplated where the
material web 100 comprise a first strata and a second strata, and
wherein the melt additive bloom area 590 is present on the filled
tuft 572 formed by the second strata. For the sake of convenience,
the melt additive bloom area 590 is shown on the filled tuft 572;
however, the melt additive bloom area 590 may be comprised by a
majority of filaments which comprise the filled tuft 572. As shown,
the melt additive bloom area 590 may be present at a distal end 554
of the filled tuft 570 and a sidewall 556 of the filled tuft
572.
[0145] In such forms, the melt additive bloom area 590 may comprise
a hydrophobic composition. Where the material web 100 is utilized
as a topsheet of a disposable absorbent article, such forms can
allow for reduction in rewet while providing adequate liquid
acquisition. Additionally, in such forms, the melt additive bloom
area 590 may help with masking of liquid insults to a disposable
absorbent article.
[0146] Referring to FIG. 5H, the material web 100 of the present
invention may comprise outer tufts 530 and filled tufts 572. As
shown, the outer tuft be a portion of the first layer 25 or first
strata which is urged in the positive Z-direction. As shown, the
second plurality of filaments of the second layer 35 or second
strata form the filled tuft 572. The first layer 25 or first strata
may similarly form an outer tuft 530 which covers the filled tuft
572. For those forms of the present invention comprising outer
tufts 530, the melt additive bloom area 592 may exist in the distal
end 554 of the outer tuft 530 and on the sidewalls 556 of the outer
tuft 530.
[0147] In such forms, the melt additive bloom area 592 may comprise
a hydrophobic composition, and the melt additive bloom area 590 may
comprise a hydrophilic composition. In some forms, the melt
additive bloom area 592 may comprise a hydrophobic composition and
the melt additive bloom area 590 may comprise a hydrophobic
composition.
[0148] Regarding FIGS. 51 and 5J, the material web 100 may be urged
in a plurality of localized areas in the negative Z-direction. In
such forms, the material web 100 may comprise a plurality of filled
tufts 572 which extend in the negative Z-direction. As shown, the
filled tufts 572 may be formed in part from the first layer 25 or
first strata. So, in such forms, the first layer 25 or first strata
may comprise a spunbond crimped nonwoven layer or strata. As shown,
in some forms, the second layer 35 or second strata may break with
the negative Z-direction urging or may form outer tufts 530. In
such forms, the melt additive bloom area 590 may comprise a
hydrophilic composition, and/or the melt additive bloom area 592
may similarly comprise a hydrophilic composition.
[0149] Where the material webs 100 of the present invention
comprise crimped filaments, the material web 100 has a higher
caliper for a given basis weight. This higher caliper can in turn
deliver consumer benefits of comfort due to cushiony softness,
faster absorbency due to higher permeability, and improved masking.
Additional benefits may include less redmarking, higher
breathability and resiliency.
[0150] Methods of making filled tufts 572 and outer tufts 530 are
discussed in U.S. Pat. Nos. 7,172,801; 7,838,099; 7,754,050;
7,682,686; 7,410,683; 7,507,459; 7,553,532; 7,718,243; 7,648,752;
7,732,657; 7,789,994; 8,728,049; and 8,153,226. Filled tufts 572
and corresponding outer tufts 530 are discussed in additional
detail in U.S. patent application Ser. No. 14/933,028.
[0151] The filled tufts 572 and/or outer tufts 530 may be used in
conjunction with the apertures and/or embossments. Or, the filled
tufts 572 and/or outer tufts 530 may be utilized independently
thereof.
[0152] Referring back to FIGS. 5A-5J, for those forms of the
present invention where the roll 502 is heated as opposed to the
roll 504, the distal ends 554 and the sidewalls 556--to a larger
extent than if only the roll 504 were heated--may comprise the melt
additive bloom area 590. Additionally, the melt additive bloom area
590 may be a stripe which connects adjacent tufts (either tunnel or
filled).
Nested Tufts
[0153] Another example of a first unit operation 140 (shown in FIG.
2) that may be utilized in conjunction with the present invention
is shown in FIGS. 6A-6D. As shown, the precursor web 102 may be
subjected to the apparatus 600. The apparatus 600 may comprise
forming members 602 and 604 which may be in the form of
non-deformable, meshing, counter-rotating rolls that form a nip 606
therebetween. The precursor web 102 may be fed into the nip 606
between the rolls 6102 and 604. Although the space between the
rolls 602 and 604 is described herein as a nip, as discussed in
greater detail below, in some cases, it may be desirable to avoid
compressing the precursor web 102 to the extent possible.
[0154] The first forming member (such as "male roll") 602 has a
surface comprising a plurality of first forming elements which
comprise discrete, spaced apart male forming elements 612. The male
forming elements are spaced apart in the machine direction and in
the cross-machine direction. The term "discrete" does not include
continuous or non-discrete forming elements such as the ridges and
grooves on corrugated rolls (or "ring rolls") which have ridges
that may be spaced apart in one, but not both, of the machine
direction and in the cross-machine direction.
[0155] As shown in FIG. 6B, the male forming elements 612 have a
base 616 that is joined to (in this case is integral with) the
first forming member 602, a top 618 that is spaced away from the
base, and sidewalls (or "sides") 620 that extend between the base
616 and the top 618 of the male forming elements. The male elements
612 may also have a transition portion or region 622 between the
top 618 and the sidewalls 620. The forming elements 612 also have a
plan view periphery, and a height H.sub.1 (the latter being
measured from the base 616 to the top 618). The tops 618 of the
forming elements 612 on the first forming member 602 may have a
relatively large surface area (e.g., from about 1 mm to about 10 mm
in width, and from about 1 mm to about 20 mm in length) for
creating a wide discontinuity in the precursor material 102. The
forming elements 612 may, thus, have a plan view aspect ratio
(ratio of length to width) that ranges from about 1:1 to about
10:1. For the purpose of determining the aspect ratio, the larger
dimension of the forming elements 612 will be consider the length,
and the dimension perpendicular thereto will be considered to be
the width of the forming element. The forming elements 612 may have
any suitable configuration.
[0156] The base 616 and the top 618 of the forming elements 612 may
have any suitable plan view configuration, including but not
limited to: a rounded diamond configuration as shown in FIGS. 6A
and 6B, an American football-like shape, triangle, circle, clover,
a heart-shape, teardrop, oval, or an elliptical shape. The
configuration of the base 616 and the configuration of the top 618
of the forming elements 612 may be in any of the following
relationships to each other: the same, similar, or different. The
top 618 of the male elements 612 can be flat, rounded, or any
configuration therebetween.
[0157] Additional forms of the male forming elements 612 are
possible. For example, the top 618 of the forming elements 612 can
be of different shapes from those shown in the drawings. As another
example, the male forming elements 612 can be disposed in other
orientations on the first forming member 602 rather than having
their length oriented in the machine direction (including
CD-orientations, and orientations between the MD and CD). The male
forming elements 612 on the first forming member 602 may, but need
not, all have the same configuration or properties. In certain
embodiments, the first forming member 602 can comprise some male
forming elements 612 having one configuration and/or properties,
and other male forming elements 612 having one or more different
configurations and/or properties.
[0158] Referring again to FIGS. 6A through 6D, the second forming
member (such as "female roll") 604 has a surface 624 having a
plurality of cavities or recesses 614 therein. The recesses 614 are
aligned and configured to receive the male forming elements 612
therein. Thus, the male forming elements 612 mate with the recesses
614 so that a single male forming element 612 fits within a
periphery of a single recess 614, and at least partially within the
recess 614 in the Z-direction. The recesses 614 have a plan view
periphery 626 that is larger than the plan view periphery of the
male elements 612. As a result, the recesses 614 on the female roll
604 may completely encompass the male forming elements 612 when the
rolls 602 and 604 are intermeshed. As shown in FIG. 6C, the
recesses 614 have a depth D1 which in some forms may be greater
than the height H.sub.1 of the male forming elements 612. The
recesses 614 have a plan view configuration, sidewalls 628, a top
edge or rim 634 around the upper portion of the recess where the
sidewalls 628 meet the surface 624 of the second forming member
604, and a bottom edge 630 around a bottom 632 of the recesses
where the sidewalls 628 meet the bottom 632 of the recesses.
[0159] As discussed above, the recesses 614 may be deeper than the
height H.sub.1 of the forming elements 612 so the precursor web 102
is not nipped (or squeezed) between the male and female rolls 602
and 604 to the extent possible. However, it is understood that
passing the precursor web between two rolls with a relatively small
space therebetween will likely apply some shear and compressive
forces to the material. The present method, however, differs from
some embossing processes in which the top of the male elements
compress the material to be embossed against the bottom of the
female elements, thereby increasing the density of the region in
which the material is compressed.
[0160] The depth of engagement (DOE) is a measure of the level of
intermeshing of the forming members. As shown in FIG. 6C, the DOE
is measured from the top 618 of the male elements 612 to the
(outermost) surface 624 of the female forming member 614 (e.g., the
roll with recesses). The DOE should be sufficiently high, when
combined with extensible nonwoven materials, to create nested
tufts. For example, for the precursor web 102 of the present
invention, the DOE may, for example, range from at least about 1.5
mm, or less, to about 5 mm, or more. In certain forms, the DOE may
be between about 2.5 mm to about 5 mm, alternatively between about
3 mm and about 4 mm.
[0161] Still referring to FIG. 6C, there is a clearance, C, between
the sides 620 of the forming elements 612 and the sides (or
sidewalls) 628 of the recesses 614. The clearances and the DOE's
are related such that larger clearances can permit higher DOE's to
be used. The clearance, C, between the male and female roll may be
the same, or it may vary around the perimeter of the forming
element 612. For example, the forming members can be designed so
that there is less clearance between the sides of the forming
elements 612 and the adjacent sidewalls 628 of the recesses 614
than there is between the sidewalls at the end of the male elements
612 and the adjacent sidewalls of the recesses 614. In other cases,
the forming members can be designed so that there is more clearance
between the sides 620 of the male elements 612 and the adjacent
sidewalls 628 of the recesses 614 than there is between the
sidewalls at the end of the male elements 612 and the adjacent
sidewalls of the recesses. In still other cases, there could be
more clearance between the side wall on one side of a male element
612 and the adjacent side wall of the recess 614 than there is
between the side wall on the opposing side of the same male element
612 and the adjacent side wall of the recess. For example, there
can be a different clearance at each end of a forming element 612;
and/or a different clearance on each side of a male element 612.
Clearances can range from about 0.005 inches (about 0.1 mm) to
about 0.1 inches (about 2.5 mm).
[0162] Some of the aforementioned forming element 612
configurations alone, or in conjunction with the second forming
member 604 and/or recess 614 configurations may provide additional
advantages. This may be due to by greater lock of the precursor
material on the male elements 612, which may result in more uniform
and controlled strain on the precursor material. The apparatus 600
is further described in U.S. patent application Ser. No.
14/844,459.
[0163] As shown in FIGS. 6D-6F, the precursor web 102 may be
provided to the nip 606 between the first roll 602 and the second
roll 604. As the precursor web 102 passes through the nip 606, the
forming members 612 engage the second surface 30 (shown in FIG. 6F
as the second surface 30 of the material web 100) of the precursor
web 102 and urge the precursor web 102 into the recesses 614. The
process forms the material web 100 comprising the generally planar
first surface 20 and a plurality of integrally formed nested tufts
632 extending outward from the first surface 20 of the material web
100 and openings in the second surface 30 of the material web 100.
(Of course, if the second surface 30 of the precursor web 102 is
placed in contact with the second forming member 604, the nested
tufts 632 will extend outward from the second surface of the
material web 100 and the openings will be formed in the first
surface 20 of the material web 100.) Without wishing to be bound by
any particular theory, it is believed that the extensibility of the
precursor material 102 (or at least one of the layers of the same)
when pushed by the forming elements 612 into the recesses 614 with
depth of engagement DOE being less than the depth D.sub.1 of the
recesses, stretches a portion of the precursor material 102 to form
a nested tuft 632.
[0164] Referring now to FIGS. 6E-6H, examples of material webs 100
comprising nested tufts 632 are shown. As noted heretofore, the
material web 100 has the first surface 20, the opposing second
surface 30, and a thickness T therebetween (the thickness being
shown in FIG. 6H). FIG. 6E shows the first surface 20 of the
material web 100 with nested tufts 632 that extend outward (out of
the plane of the sheet comprising FIG. 6E) from the first surface
20 of the material web 100. As shown, the material web 100 may
comprise a generally planar first region 640 and a plurality of
discrete integral second regions 642 which comprise nested tufts
632.
[0165] As shown, the nested tufts 632 may have a width, W, that
varies from one end 660 to the opposing end 660 when the nested
tufts 632 are viewed in plan view. As shown, the width W may be
generally parallel to a transverse axis TA. The width W may vary
with the widest portion of the nested tufts 632 in the middle of
the nested tufts 632, and the width of the nested tufts 632
decreasing at the ends 660 of the nested tufts 632. In other cases,
the nested tufts 632 could be wider at one or both ends 60 than in
the middle of the nested tufts 632. In still other cases, nested
tufts 632 can be formed that have substantially the same width from
one end of the nested tufts 632 to the other end of the nested
tufts 632. If the width of the nested tufts 632 varies along the
length of the nested tufts 632, the portion of the nested tufts 632
where the width is the greatest is used in determining the aspect
ratio of the nested tufts 632.
[0166] Similarly, the nested tufts 632 may have a length L which is
generally parallel to a longitudinal axis LA. When the nested tufts
632 have a length L that is greater than or less than their width
W, the length of the nested tufts 632 may be oriented in any
suitable direction relative to the material web 100. For example,
the length of the nested tufts 632 (that is, the longitudinal axis,
LA, of the nested tufts 632) may be oriented in the MD, the CD, or
any desired orientation between the MD and the CD. As shown, the
transverse axis TA is generally orthogonal to the longitudinal axis
LA in the MD-CD plane. In some forms, as shown, the longitudinal
axis LA is parallel to the MD. In some forms, all the spaced apart
nested tufts 632 may have generally parallel longitudinal axes
LA.
[0167] FIG. 6F shows the second surface 30 of a material web 100
such as that shown in FIG. 6E, having nested tufts 632 formed
therein, with the nested tufts 632 being oriented into the sheet
showing FIG. 6F. The second surface 30 may comprise a plurality of
base openings 644. In some forms, the base openings 644 may not be
in the form of an aperture or a through-hole. The base openings 644
may instead appear as depressions. In some forms, the base openings
644 may open into the interior of the nested tuft 632.
[0168] Referring to FIGS. 6E, 6G and 6H, the nested tufts 632 may
have any suitable shape when viewed from the side. Suitable shapes
include those in which there is a distal portion or "cap" with an
enlarged dimension and a narrower portion at the base when viewed
from at least one side. The term "cap" is analogous to the cap
portion of a mushroom. (The cap does not need to resemble that of
any particular type of mushroom. In addition, the nested tufts 632
may, but need not, have a mushroom-like stem portion.) In some
cases, the nested tufts 632 may be referred to as having a bulbous
shape when viewed from the end 660. The term "bulbous", as used
herein, is intended to refer to the configuration of the nested
tufts 632 as having a cap 652 with an enlarged dimension and a
narrower portion at the base when viewed from at least one side
(particularly when viewing from one of the shorter ends 660) of the
nested tufts 632. The term "bulbous" is not limited to nested tufts
632 that have a circular or round plan view configuration that is
joined to a columnar portion. The bulbous shape, in the form shown
(where the longitudinal axis LA of the nested tufts 632 is oriented
in the machine direction), may be most apparent if a section is
taken along the transverse axis TA of the nested tufts 632 (that
is, in the cross-machine direction). The bulbous shape may be less
apparent if the nested tufts 632 is viewed along the length (or
longitudinal axis LA) of the nested tufts 632.
[0169] Referring to FIGS. 6E-6H, an example of a multi-layer
material web 100 having a nested tuft 632 on one side of the
material web 100 and a wide base opening 644 on the other side of
the material web 100 is shown. As shown, the base opening 644 is
oriented upward in the figure. When there is more than one layer,
the individual layers can be designated 630A, 630B, etc. As shown,
the nested tufts 632 may comprise: a base 650 proximate the first
surface 20 of the material web 100; an opposed enlarged distal
portion or cap portion, or "cap" 652, that extends to a distal end
654; sidewalls (or "sides") 656; an interior 658; and a pair of
ends 660. The "base" 650 of the nested tufts 632 comprises the
narrowest portion of the nested tufts 632 when viewed from one of
the ends of the nested tufts 632. The term "cap" does not imply any
particular shape, other than it comprises the wider portion of the
nested tufts 632 that includes and is adjacent to the distal end
654 of the nested tufts 632. The sidewalls 656 have an inside
surface and an outside surface. The sidewalls 656 transition into,
and may comprise part of the cap 652. Therefore, it is not
necessary to precisely define where the sidewalls 656 end and the
cap 652 begins. The cap 652 will have a maximum interior width,
W.sub.1, between the inside surfaces of the opposing sidewalls 656.
The cap 652 will also have a maximum exterior width W between the
outside surfaces of the opposing sidewalls 656. The ends 660 of the
nested tufts 632 are the portions of the nested tufts 632 that are
spaced furthest apart along the longitudinal axis, L, of the nested
tufts 632.
[0170] Still referring to FIGS. 6E-6H, the narrowest portion of the
nested tufts 632 defines the base opening 644. The base opening 644
has a width W.sub.O. The base opening 644 may be located (in the
Z-direction) between a plane defined by the second surface 30 of
the material web 100 and the distal end 654 of the nested tuft 632.
The material web 100 may have an opening in the second surface 30
that transitions into the base opening 644 (and vice versa), and is
the same size as, or larger than the base opening 644. The base
opening 644 will, however, generally be discussed more frequently
herein since its size will often be more visually apparent to the
consumer in those embodiments where the material web 100 is placed
in an article with the base openings 644 visible to the consumer.
It should be understood that in certain forms of the present
invention, base openings 644 face outward (for example, toward a
consumer and away from the absorbent core in an absorbent article),
it may be desirable for the base openings 644 not to be covered
and/or closed off by another web.
[0171] The nested tufts 632 have a depth D measured from the second
surface 30 of the material web 100 to the interior of the nested
tufts 632 at the distal end 654 of the nested tufts 632. The nested
tufts 632 have a height H measured from the second surface 30 of
the material web 100 to the exterior of the nested tuft 632 at the
distal end 654. In most cases the height H of the nested tufts 632
will be greater than the thickness T of the first region 640. The
relationship between the various portions of the nested tufts 632
may be such that as shown in FIG. 6H, when viewed from the end, the
maximum interior width W.sub.I of the cap 652 of the nested tufts
632 is wider than the width, W.sub.O, of the base opening 644.
[0172] For those forms of the present invention where the material
web 100 comprises a nonwoven material, the nested tufts 632 may, in
some cases, be formed from looped fibers (which may be continuous)
that are pushed outward so that they extend away from the first
surface 20 in the Z-direction or away from the second surface 30 in
the negative Z-direction. The nested tufts 632 will typically
comprise more than one looped fiber. In some cases, the nested
tufts 632 may be formed from looped fibers and at least some broken
fibers. In addition, in the case of some types of nonwoven
materials (such as carded materials, which are comprised of shorter
fibers), the nested tufts 632 may be formed from loops comprising
multiple discontinuous fibers. Multiple discontinuous fibers in the
form of a loop are described in U.S. patent application Ser. No.
14/844,459. The looped fibers may be: aligned (that is, oriented in
substantially the same direction); not be aligned; or, the fibers
may be aligned in some locations within the protrusions 32, and not
aligned in other parts of the protrusions.
[0173] In some forms, if male/female forming elements are used to
form the nested tufts 632, and the female forming elements
substantially surround the male forming elements, the fibers in at
least part of the nested tufts 632 may remain substantially
randomly oriented (rather than aligned), similar to their
orientation in the precursor web(s). For example, in some cases,
the fibers may remain substantially randomly oriented in the cap of
the nested tufts 632, but be more aligned in the sidewalls such
that the fibers extend in the Z-direction (positive or negative
depending on the orientation of the nested tuft 632) from the base
of the protrusions to the cap. In addition, if the precursor web
comprises a multi-layer nonwoven material, the alignment of fibers
can vary between layers, and can also vary between different
portions of a given nested tufts 632 within the same layer.
[0174] Where the precursor web comprises a nonwoven material, the
nested tufts 632 may comprise a plurality fibers that at least
substantially surround the sides of the nested tufts 632. This
means that there are multiple fibers that extend (e.g., in the
positive or negative Z-direction) from the base 650 of the nested
tufts 632 to the distal end 654 of the nested tufts 632, and
contribute to form a portion of the sides 656 and cap 652 of a
nested tufts 632. In some cases, the fibers may be substantially
aligned with each other in the Z-direction in the sides 656 of the
nested tufts 632. The phrase "substantially surround", thus, does
not require that each individual fiber be wrapped in the X-Y plane
substantially or completely around the sides of the nested tufts
632. If the fibers are located completely around the sides of the
nested tufts 632, this would mean that the fibers are located
360.degree. around the nested tufts 632. The nested tufts 632 may
be free of large openings at their ends 660. In some cases, the
nested tufts 632 may have an opening at only one of their ends,
such as at their trailing end.
[0175] In some forms, similar-shaped looped fibers may be formed in
each layer of multiple layer nonwoven materials, including in the
layer 630A that is spaced furthest from the discrete male forming
elements during the process of forming the nested tufts 632
therein, and in the layer 630B that is closest to the male forming
elements during the process. In the nested tufts 632, portions of
one layer such as 630B may fit within the other layer, such as
630A. These layers may be referred to as forming a "nested"
structure in the nested tufts 632. Formation of a nested structure
may require the use of two (or more) highly extensible nonwoven
precursor webs. In the case of two layer materials, nested
structures may form two complete loops, or (as shown in some of the
following drawing figures) two incomplete loops of fibers.
[0176] The nested tufts 632 may have certain additional
characteristics. As shown in FIGS. 6G and 6H, the nested tufts 632
may be substantially hollow. As used herein, the term
"substantially hollow" refers to structures which the nested tufts
632 are substantially free of fibers in interior of nested tuft.
The term "substantially hollow", does not, however, require that
the interior of the nested tuft must be completely free of fibers.
Thus, there can be some fibers inside the nested tufts 632.
"Substantially hollow" nested tufts are distinguishable from filled
three-dimensional structures, such as those made by laying down
fibers, such as by airlaying or carding fibers onto a forming
structure with recesses therein.
[0177] The sidewalls 656 of the nested tufts 632 can have any
suitable configuration. The configuration of the sidewalls 656,
when viewed from the end of the nested tuft such as in 6G, can be
linear or curvilinear, or the sidewalls can be formed by a
combination of linear and curvilinear portions. The curvilinear
portions can be concave, convex, or combinations of both. For
example, the sidewalls 656 may comprise portions that are
curvilinear concave inwardly near the base of the nested tuft and
convex outwardly near the cap of the nested tuft. The sidewalls 656
and the area around the base opening 644 of the nested tuft may
have significantly lower concentration of fibers per given area
(which may be evidence of a lower basis weight or lower opacity)
than the portions of the first region 640. The nested tufts 632 may
also have thinned fibers in the sidewalls 656. The fiber thinning,
if present, will be apparent in the form of necked regions in the
fibers. Thus, the fibers may have a first cross-sectional area when
they are in the undeformed precursor material 102, and a second
cross-sectional area in the sidewalls 656 of the nested tufts 632
of the deformed material web 100, wherein the first cross-sectional
area is greater than the second cross-sectional area. The sidewalls
656 may also comprise some broken fibers as well. In some forms,
the sidewalls 656 may comprise greater than or equal to about 30%,
alternatively greater than or equal to about 50% broken fibers.
[0178] In some forms, the distal end 654 of the nested tufts 632
may be comprised of original basis weight, non-thinned, and
non-broken fibers. If the base opening 44 faces upward, the distal
end 654 will be at the bottom of the depression that is formed by
the nested tuft. The distal end 654 will be free from apertures
formed completely through the distal end. Thus, the nonwoven
materials may be nonapertured. The term "apertures", as used
herein, refers to holes formed in the nonwovens after the formation
of the nonwovens, and does not include the pores typically present
in nonwovens. The term "apertures" also does not refer to irregular
breaks (or interruptions) in the nonwoven material(s) resulting
from localized tearing of the material(s) during the process of
forming nested tufts therein, which breaks may be due to
variability in the precursor material(s). The distal end 654 may
have relatively greater fiber concentration in comparison to the
remaining portions of the structure that forms the protrusions. The
fiber concentration can be measured by viewing the sample under a
microscope and counting the number of fibers within an area.
[0179] The nested tufts 632 may be of any suitable shape. Since the
nested tufts 632 are three-dimensional, describing their shape
depends on the angle from which they are viewed. When viewed from
above (that is, perpendicular to the plane of the web, or plan
view) such as in FIG. 6E, suitable shapes include, but are not
limited to: circular, diamond-shaped, rounded diamond-shaped, U.S.
football-shaped, oval-shaped, clover-shaped, heart-shaped,
triangle-shaped, tear-drop shaped, and elliptical-shaped. (The base
openings 644 will typically have a shape similar to the plan view
shape of the nested tufts 632.) In other cases, the nested tufts
632 (and base openings 644) may be non-circular. The nested tufts
632 may have similar plan view dimensions in all directions, or the
nested tufts 632 may be longer in one dimension than another. That
is, the nested tufts 632 may have different length and width
dimensions. If the nested tufts 632 have a different length than
width, the longer dimension will be referred to as the length of
the nested tufts 632. The nested tufts 632 may, thus, have a ratio
of length to width, or an aspect ratio. The aspect ratios can range
from about 1:1 to about 10:1.
[0180] In some forms, the length of the cap 652 may be in a range
from about 1.5 mm to about 10 mm. In some forms, the width of the
cap (measured where the width is the greatest) may be in a range
from about 1.5 mm to about 5 mm. The cap portion of the protrusions
may have a plan view surface area of at least about 3 mm.sup.2. In
some embodiments, the protrusions may have a pre-compression height
H that is in a range from about 1 mm to about 10 mm, alternatively
from about 1 mm to about 6 mm. In some embodiments, the protrusions
may have a post-compression height H that is in a range from about
0.5 mm to about 6 mm, alternatively from about 0.5 mm to about 1.5
mm. In some embodiments, the protrusions may have a depth D, in an
uncompressed state that is in a range from about 0.5 mm to about 9
mm, alternatively from about 0.5 mm to about 5 mm. In some
embodiments, the protrusions may have a depth D, after compression
that is in a range from about 0.25 mm to about 5 mm, alternatively
from about 0.25 mm to about 1 mm.
[0181] For those forms of the present invention where the material
web 100 comprises a first layer and a second layer many
configurations may be achieved. In such forms, the first layer may
be incorporated into an absorbent article as, for example, an
acquisition layer and the second layer may be a topsheet of the
absorbent article. Each of the first layer and the second layer may
form nested tufts which fit into one another. Such examples are
described with regard to FIGS. 6I-6N.
[0182] For the examples shown in FIGS. 6I-6N, each of the nested
tufts formed by the first layer 630A and second layer 630B may
comprise a plurality of fibers. In addition, for any of the forms
comprising nested tufts, the nonwoven layers can be inverted when
incorporated into an absorbent article, or other article, so that
the nested tufts 632 face upward (or outward). In such a case, the
material suitable for the topsheet will be used in layer 630A, and
material suitable for the underlying layer will be used in layer
630B.
[0183] As shown in FIG. 6I, a nested tuft 632 may comprise a
compound nest. As shown, the nested tuft 632 may comprise a first
nested tuft 632A formed in the first layer 630A and a second nested
tuft 632B formed in the second layer 630B. In one form, the first
layer 630A may be incorporated into an absorbent article as an
acquisition layer, and the second layer 630B may be a topsheet, and
the nested tufts 632 formed by the two layers may fit together
(that is, are nested). In some forms, the fibers 638A in the first
layer 630A are shorter in length than the fibers 638B in the second
layer 630B. In other forms, the relative length of fibers in the
layers may be the same, or in the opposite relationship wherein the
fibers in the first layer are longer than those in the second
layer.
[0184] FIG. 6J shows that the nonwoven layers need not be in a
contacting relationship within the entirety of the nested tuft 632.
Thus, the first nested tuft 632A and second nested tuft 632B formed
by the first and second layers 630A and 630B may have different
heights and/or widths. The two materials may have substantially the
same shape in the nested tuft 632 as shown in 6J (where one of the
materials has the same the curvature as the other). In other forms,
however, the layers may have different shapes. It should be
understood that FIG. 6J shows only one possible arrangement of
layers, and that many other variations are possible, but that as in
the case of all the figures, it is not possible to provide a
drawing of every possible variation.
[0185] As shown in FIG. 6K, one of the layers, such as first layer
630A (e.g., an acquisition layer) may be ruptured in the area of
the nested tuft 632. As shown in FIG. 6K, the nested tufts 632 are
only formed in the second layer 630B (e.g., the topsheet) and
extend through openings in the first layer 630A. That is, the
second nested tuft 632B in the second layer 630B interpenetrates
the ruptured first layer 630A. Such a structure may place the
topsheet in direct contact an underlying distribution layer or
absorbent core, which may lead to improved dryness. In such forms,
the layers are not considered to be "nested" in the area of the
protrusion. (In the other embodiments shown in FIGS. 6L-6N, the
layers would still be considered to be "nested".) Such a structure
may be formed if the material of the second layer 630B is much more
extensible than the material of the first layer 630A. For some
materials, portions of the first layer 630A can be deflected or
urged out-of-plane (i.e., out of the plane of the first layer 630A)
to form flaps 670. The form and structure of any flaps is highly
dependent upon the material properties of the first layer 630A.
Flaps can have the general structure shown in FIG. 6K. In other
forms, the flaps 670 can have a more volcano-like structure, as if
the second nested tuft 632B is erupting from the flaps.
[0186] Alternatively, as shown in FIGS. 6L-6N, one or both of the
first layer 630A and the second layer 630B may be interrupted (or
have a break therein) in the area of the nested tuft 632. FIGS. 6L
and 6M show that the first nested tuft 632A of the first layer 630A
may have an interruption 672A therein. The second nested tuft 632B
of the non-interrupted second layer 630B may coincide with and fit
together with the first nested tuft 632A of the interrupted first
layer 630A. Alternatively, FIG. 6N shows an embodiment in which
both the first and second layers 630A and 630B have interruptions,
or breaks, therein (672A and 672B, respectively). In this case, the
interruptions in the layers 630A and 630B are in different
locations in the nested tuft 632. FIGS. 6L-6N show unintentional
random or inconsistent breaks in the materials typically formed by
random fiber breakage, which are generally misaligned and can be in
the first or second layer, but are not typically aligned and
completely through both layers. Thus, there typically will not be
an aperture formed completely through all of the layers at the
distal end 654 of the nested tuft 632.
[0187] For dual layer and other multiple layer structures, the
basis weight distribution (or the concentration of fibers) within
the material web 100, as well as the distribution of any thermal
point bonds can be different between the layers. As used herein,
the term "fiber concentration" has a similar meaning as basis
weight, but fiber concentration refers to the number of
fibers/given area, rather than g/area as in basis weight. In the
case of bond sites, the fibers may be melted which may increase the
density of the material in the bond sites 46, but the number of
fibers will typically be the same as before melting.
[0188] Some such dual and multiple layer nonwoven materials may be
described in terms of such differences between layers, without
requiring one or more of the other features described herein (such
as characteristics of the cap portion; controlled collapse under
compression; and varying width of the protrusions). Of course such
dual and multiple layer nonwoven materials may have any of these
other features.
[0189] In such dual and multiple layer nonwoven materials each of
the layers comprises a plurality of fibers, and in certain
embodiments, the nested tufts 632 will be formed from fibers in
each of the layers. Referring back to FIGS. 6E-6H, for example, one
of the layers, a first layer, may form the first surface 20 of the
material web 100, and one of the layers, a second layer, may form
the second surface 30 of the material web 100. A portion of the
fibers in the first layer form part of: the first region 640, the
sidewalls 656 of the nested tuft 632, and the distal ends 654 of
the nested tuft 632. A portion of the fibers in the second layer
may form part of: the first region 640, the sidewalls 656 of the
nested tufts 632, and the distal ends 654 of the nested tuft
632.
[0190] Referring back to FIGS. 6A-6E, forms of the present
invention are contemplated where the first forming member 602
and/or the second forming member 604 are heated or portions
thereof. For example, the forming elements 612 may be heated
including the base 616, the top 618, sidewalls 620 that extend
between the base 616 and the top 618, and/or the transition region
622 between the top 618 and the sidewalls 620. As another example,
the recesses 614 may be heated including the sidewalls 628, the top
edge or rim 634, and/or a bottom edge 630 of the recesses 614. In
some forms, the surface 624 of the second forming member 604 may
not be heated.
[0191] Forms of the present invention are contemplated where only a
portion of the number of forming elements are heated and/or only a
portion of the number of recesses 614 are heated. For example, in
some forms, every third forming member 612 may be heated and/or
every third recess 614 may be heated. Any suitable configuration
may be utilized. In some forms, patterns of heated forming elements
612 and/or recesses 614 may be utilized.
[0192] For those forms comprising heated forming elements 612
and/or recesses 614, melt additive blooms may be provided in the
resultant material web. For example, as shown in FIG. 6O, in
conjunction with FIGS. 6A-6D, where forming members 612 are heated
a melt additive bloom area 690 may be provided on a portion of the
sidewalls 656 and distal end 654 of the material web 100. Where the
corresponding recesses 614 are also heated, the melt additive bloom
area 690 may extend closer to the neck 650 of the nested tuft 632.
As shown, for those forms of the present invention where the nested
tufts 632 extend in the negative Z-direction (away from a user of a
disposable absorbent article), the melt additive bloom area 690 may
comprise a hydrophilic composition. For those forms of the present
invention where the nested tufts 632 extend in the positive
Z-direction (toward the user of a disposable absorbent article),
the melt additive bloom area 690 may comprise a hydrophobic
composition.
[0193] For those forms of the present invention where the material
web 100 comprises multiple layers, the nested tufts 632 may
comprise a plurality of melt additive bloom areas. For example, as
shown in FIG. 6P, in conjunction with FIGS. 6A-6D, the material web
100 comprises the first layer 630A and the second layer 630B. Where
the forming elements 612 are heated, melt additive bloom areas 690
and 695 may be provided at the distal end of the nested tuft 632.
Specifically, the melt additive area 695 may be provided on the
first nested tuft 632A, and the melt additive area 590 may be
provided on the second nested tuft 632B. Where the corresponding
recesses 614 are also heated, the melt additive areas 690 and 695
may extend toward the neck 650 of the nested tuft 632. As shown,
the nested tuft 632 may extend in the negative Z-direction (away
from a user of a disposable absorbent article). In such forms, the
melt additive areas 590 and 595 may comprise a hydrophilic
composition to facilitate liquid acquisition. For those forms where
the nested tuft 632 extends in the positive Z-direction (toward a
user of a disposable absorbent article) the melt additive areas 590
and 595 may comprise a hydrophobic composition to reduce the
likelihood of rewet and/or increase the masking of any liquid
induced stains in the disposable absorbent article. Forms of the
present invention are contemplated where the melt additive bloom
area 595 comprises a hydrophobic composition while the melt
additive area 590 comprises a hydrophilic composition. Such forms
may be useful where the nested tufts 632 are configured as shown
with regard to FIGS. 6L-6N. In such forms, the second layer 630B
may have access to liquid insults due to the disruption in the
first layer 630A. So, the hydrophilic composition may facilitate
liquid acquisition while the hydrophobic composition of the melt
additive bloom area 595 may provide adequate masking and reduction
of rewet characteristics.
[0194] The nested tufts 632 of the present invention may be
utilized in conjunction with the tunnel tufts, outer tufts, filled
tufts, apertures, and/or embossments described herein.
Corrugations
[0195] Another example of a first unit operation 140 (shown in FIG.
2) that may be utilized in conjunction with the present invention
is shown in FIGS. 7A-7E. As shown in FIG. 7A, the material web 100
of the present invention may be created, in some forms via
apparatus 700. The precursor web 102 is provided to a running belt
710 which has air-permeability in its thickness direction. The
running belt 710 runs in the MD as shown. In some forms of the
present invention, the precursor web 102 may subjected to a
plurality of air jets 721 from a manifold of nozzles 720. The
plurality of air jets 721 blast the precursor web 102 with a
plurality of air streams which are sucked through the running belt
710 via a suction box 712. The plurality of air streams provided by
the plurality of air jets 721 heave the precursor web 102 in the CD
direction so that the precursor web 102 can be formed with ridges
between adjacent air jets 721. Additional description regarding the
creation of corrugations can be found in U.S. Pat. Nos. 6,458,447;
7,270,861; 8,502,013; 7,954,213; 7,625,363; 8,450,557; 7,741,235;
US Patent Application Publication Nos. US2003/018741;
US2009/0240222; US2012/0045620; US20120141742; US20120196091;
US20120321839; US2013/0022784; US2013/0017370; US2013/013732;
US2013/0165883; US2013/0158497; US2013/0280481; US2013/0184665;
US2013/0178815; US2013/0236700; PCT Patent Application Publication
Nos. WO2008/156075; WO2010/055699; WO2011/125893; WO2012/137553;
WO2013/018846; WO2013/047890; and WO2013/157365.
[0196] Subsequent to the blasting of the precursor web 102 with air
streams, the material web 100 may comprise a plurality of
corrugations. Some exemplary corrugations are shown in FIGS. 7B-7E.
As shown, the material web 100 of the present invention may
comprise corrugations 770 which can extend in a direction generally
parallel to the MD or generally parallel to the CD. The
corrugations 770 may comprise any suitable shape. For example, as
shown, the corrugations 770 may have an arcuate shape. As another
example, the corrugations 770 may comprise a triangular shape.
Regardless of the shape of the corrugations 770, may
comprise--similar to their tuft counterparts--a distal end 754 and
sidewalls 756 extending from a groove 775. Additionally, examples
are contemplated where a nonwoven web constructed in accordance
with the present invention comprises at least one ridge having an
arcuate shape and one ridge comprising a triangular shape.
[0197] As noted above, the air streams which impact the precursor
web 102 are heated. And as the corrugations 770 form between
adjacent air streams, the air streams form the grooves 775 of the
material web 100. The heat associated with the air streams can
create melt additive blooms in the material web 100. For example,
still referring to FIGS. 7B-7E, melt additive bloom areas 790 may
be provided in the grooves 775 of the material web 100. Where the
distal ends 754 are oriented in the positive Z-direction (facing
toward a user of a disposable absorbent article) the melt additive
areas 790 may comprise a hydrophilic composition. Where distal ends
754 are oriented in the negative Z-direction (facing away from a
user of a disposable absorbent article) the melt additive areas 790
may comprise a hydrophobic composition.
[0198] Additional forms of the present invention are contemplated
where the corrugations 770 comprise a melt additive bloom area in
addition to the melt additive bloom area 790 in the grooves 775.
For such forms, the suction box 712 may comprise discrete heated
portions which correspond to the distal ends 754 of the material
web 100.
[0199] The utilization of corrugations 770 may provide softness
benefits to the material web 100. Additionally, the material web
100 may have higher permeability in the corrugations 770. The
utilization of corrugations may be done in conjunction with
apertures, embossments, outer tufts, tunnel tufts, and/or nested
tufts described herein. Referring to FIG. 15, in some forms, an
apparatus 755 may be utilized in addition to the apparatus 700. In
such forms, corrugations in both the MD and CD may be provided to
the material web 100. Or, in some forms, the apparatus 755 may be
utilized independently of the apparatus 700 to provide corrugations
in the MD and CD on the material web 100.
[0200] As shown, the precursor material 102 may be provided to a
nip 706 between intermeshing rolls 702 and 704. The intermeshing
rolls 702 and 704 may comprise a surfaces wherein each of the
surfaces comprise concave and convex patterns, for example, as
shown in FIG. 16 are formed. In such forms, tension is applied to
the precursor web 102 during processing. The dimensions D1, D2, and
D3 of the corrugations 770 correlate to the spacing of the
concave/convex patterns on the rolls 702 and 704 in the MD. The
dimensions D4, D5, D6 correlate to the concave/convex patterns on
the rolls 702 and 704 in the CD. The concave and convex patterns on
the rolls 702 and 704 are configured to mesh with each other such
that the convex portions of roll 702 engage with the concave
portions of roll 704 and vice versa. The density of the material
web 100 at the sidewalls 756 can be changed by adjusting the depths
and the like of the rollers 702 and 704 as needed.
[0201] In some forms, the roll 702 and/or 704 may be selectively
heated. For example, as shown, the convex portion of roll 704 may
be heated to provide melt additive bloom areas 790 on the distal
ends 754 of the corrugations. In some forms, the corresponding
concave portions of roll 702 may also be heated to provide the melt
additive bloom areas 790 on the distal ends 754 of the
corrugations. The heating of the convex portions of roll 704 and/or
the concave portions of roll 702 may also provide the melt additive
bloom area 790 on the sidewalls 756 of the corrugations 770.
[0202] In other forms, the convex portions of roll 702 may be
heated to provide melt additive bloom areas in the grooves 775
between adjacent corrugations. The concave portions of the roll 704
may similarly be heated to facilitate the creation of the melt
additive bloom areas in the grooves. The heating of the convex
portions of the roll 702 and/or the concave portions of the roll
704 may also provide melt additive bloom areas on the sidewalls 756
of the corrugations 770. Forms of the present invention are
contemplated where only a portion of the distal ends 754 comprise a
melt additive bloom area 790.
[0203] Referring to FIGS. 22A through 22D, in some forms, an
apparatus 2200 may be utilized to create corrugations in the
precursor web 102. The apparatus 2200 of the present invention
which comprises a single pair of counter-rotating, intermeshing
rolls 2202, 2204 that form a single nip N therebetween. As shown
in, the first roll 2202 comprises a plurality of grooves 2210 and
ridges 2220 and a plurality of staggered, spaced-apart teeth 2230
extending outwardly from the top surface 2222 of the ridges 2220.
The configuration of the roll 2202 is such that the top surface
2222 of the ridges 2220 is disposed between the tips 2234 of the
teeth 2230 and the bottom surface 2212 of the grooves 2210,
directionally relative to the axis A of the roll.
[0204] As shown, the second roll 2204 comprises a plurality of
grooves 2240 and ridges 2250. The grooves 2240 have a bottom
surface 2242 and the ridges 2250 have a top surface 2252. Here, the
distance between the top surfaces 2252 of the ridges 2250 and the
bottom surfaces 2242 of the grooves 2240 is substantially the same
around the circumference of the roll. The teeth 2230 and ridges
2220 of the first roll 2202 extend toward the axis A of the second
roll 2204, intermeshing to a depth beyond the top 2252 of at least
some of the ridges 2250 on the second roll 2204.
[0205] Teeth suitable for this process may be conducive to
aperturing webs. The teeth on the rolls may have any suitable
configuration. A given tooth can have the same plan view length and
width dimensions (such as a tooth with a circular or square shaped
plan view). Alternatively, the tooth may have a length that is
greater than its width (such as a tooth with a rectangular plan
view), in which case, the tooth may have any suitable aspect ratio
of its length to its width. Suitable configurations for the teeth
include, but are not limited to: teeth having a triangular-shaped
side view; square or rectangular-shaped side view; columnar shaped;
pyramid-shaped; teeth having plan view configurations including
circular, oval, hour-glass shaped, star shaped, polygonal, and the
like; and combinations thereof. Polygonal shapes include, but are
not limited to rectangular, triangular, pentagonal, hexagonal, or
trapezoidal. The side-walls of the teeth may taper at a constant
angle from the base to the tip, or they may change angles. The
teeth may taper towards a single point at the tooth tip, like that
shown in FIG. 22A. The teeth can have tips that are rounded, flat
or form a sharp point. In some forms, the tip of the tooth may form
a sharp vertex with at least one of the vertical walls of the tooth
(for example, the vertical walls on the leading and trailing ends
of the teeth so the teeth aperture or puncture the web. In some
forms, each tooth may form 2 apertures, one at the leading edge and
one at the trailing edge of each tooth.
[0206] The apparatus 2200 can deform the precursor web creating
alternating regions of higher and lower caliper, and alternating
regions of higher and lower basis weight, with the higher caliper
and higher basis weight regions being located in the tops of the
ridges and bottoms of the grooves, and the regions with lower
caliper and lower basis weight located in the sidewalls in-between.
FIG. 23 is a top view of a 25 gsm polyethylene film web 2310 (film
is stretched/flattened out to show high basis weight regions 2312
and low basis weight regions 2314). Web 2310 further shows ridges
R, grooves G, and sidewalls S. Apertures 2316 are present in the
grooves G. As apparent, the high basis weight regions 2312 are
located in the ridges R and grooves G, whereas the low basis weight
regions 2314 are located in the sidewalls S.
[0207] In the case of a nonwoven, the basis weight is also
decreased in the stretched areas, again resulting in a web with
alternating regions of higher and lower basis weight, with the
higher basis weight regions located in the tops of the ridges and
bottoms of the grooves, and the lower basis weight regions located
in the sidewalls in-between. FIG. 24 is a top view of a 60 gsm
polypropylene nonwoven web 2420 (nonwoven is stretched/flattened
out to show high basis weight regions 2422, and low basis weight
regions 2424). Web 2420 further shows ridges R, grooves G, and
sidewalls S. Apertures 2426 are present in the grooves G. Thermal
or fusion bond points 2428 may be present in various locations on
the web 2420. As apparent, the high basis weight regions 2422 are
located in the ridges R and grooves G, whereas the low basis weight
regions 2424 are located in the sidewalls S. In the case of a
nonwoven, the web thickness may not decrease in the stretched
regions because the fibers may detangle and move away from each
other. However, the thickness of some of the individual fibers may
decrease as a result of the stretching. Note that the "regions" of
the web used to characterize basis weight exclude the apertures
themselves.
[0208] FIG. 25 is a cross-section view of the web 2420 shown in
FIG. 24 showing ridges R, grooves G, and axis X drawn horizontally
through a cross-section of the web; the area above the X axis but
under the top of the ridge is hollow, or comprises a hollow area
HA. Likewise, the area below the X axis but above the bottom of the
groove is hollow, or comprises a hollow area HA. Suitably, the web
thickness at the tops of the ridges and the web thickness at the
bottoms of the grooves are similar. The web thickness at the tops
of the ridges and the web thickness at the bottoms of the grooves
may be similar to the web thickness at the sidewalls. By similar,
it is meant that the thicknesses are within about 60% of one
another. Or, the web thickness at the tops of the ridges and the
web thickness at the bottoms of the grooves is greater than the web
thickness at the sidewalls. FIG. 26 is side perspective view of
another nonwoven web 2630 having ridges 2632, grooves 2634, and
sidewalls 2636. FIG. 27 is a top perspective view of 28 gsm
polyethylene/polypropylene bico nonwoven web 2740 comprising ridges
2742 and grooves 2744 and apertures 2746 wherein the aperture width
W.sub.a is greater than the ridge width W.sub.r.
[0209] Webs made by the processes and apparatuses described herein
may comprise ridges that run discontinuously across a deformed
zone, or, ridges that run continuously across a deformed zone. To
create such apertured web materials, the rolls used may comprise
zones of ridges and grooves. Or, the rolls can have zones where the
ridges are different heights, thereby creating differing depth of
engagement (DOE), differing depth below the raised ridge, and thus
apertures with differing widths and open areas. Alternatively or in
addition, the rolls may comprise different zones, wherein ridge
heights are different in different zones.
[0210] Referring back to FIGS. 22A-22D, forms of the present
invention are contemplated where the rolls 2202 and/or 2204 are
heated. For example, the spaced-apart teeth 2230 may be heated. In
such forms, the apertures formed (the outer periphery thereof) may
comprise a corresponding melt additive bloom area. In such forms,
the melt additive bloom area may comprise a hydrophilic
composition. As another example, the ridges 2220 may be heated. In
such forms, the grooves of the material web 100 may comprise a
corresponding melt additive bloom area. In such forms, particularly
where the material web 100 forms a portion of a topsheet of an
absorbent article, where the grooves are oriented away from a user
of the absorbent article, the melt additive bloom areas may
comprise a hydrophilic composition.
[0211] In some forms, the second roll 2204 may be heated. For
example, the ridges 2250 of the second roll 2204, particularly the
top surface 2252, may provide the material web 100 with melt
additive bloom areas which correspond to the ridges on the material
web 100. In such forms, the melt additive bloom areas may comprise
a hydrophobic composition. In such forms, particularly where the
material web 100 forms a portion of a topsheet of an absorbent
article, where the ridges are oriented toward the wearer of the
absorbent article. In such forms, the material web 100 can provide
masking benefits to liquid insults.
[0212] Still in other forms of the present invention, the material
web 100 may comprise rib like elements 3770 (corrugations) shown in
FIG. 30B. The corrugations 3770 comprise a major axis and a minor
axis defining an elongated cubical, ellipsoidal or other similar
rib-like shape. The major axis and the minor axis of the
corrugations 3770 may each be linear, curvilinear or a combination
of linear and curvilinear. Each of the corrugations 3770 comprises
a distal end 3754 and sidewalls 3756 extending from the generally
planar first surface 20. Forms of the present invention are
contemplated where the material web 100 comprises an undeformed
first region 3740.
[0213] Referring now to FIGS. 30A and 30B, the first and second
regions of the material web 100 may be formed from a precursor web
that is substantially planar. Said starting precursor web cab be
fed through that apparatus 3800 which forms the corrugations 3770
of the material web 100 in predefined areas resulting in corrugated
second regions of the material web and undeformed regions 3740 of
the material web 100. As shown, apparatus 3800 includes a pair of
rolls 3852 and 3854. Rolls 3852 and 3854 each have a plurality of
toothed regions 3856 and grooved regions 3858 extending about the
circumference of rolls 3852 and 3854 respectively. As the starting
precursor web passes between 3852 and 3854, the grooved regions
3858 will leave portions of the precursor web unformed, while the
portions of the precursor web passing between toothed regions 3856
will be formed producing the corrugations 3770. To lock constituent
material of the material web 100 in the second regions of the
material web 100, the rolls 3852 and 3854 may be heated. In some
forms, one of the rolls 3852 and 3854 may be heated.
[0214] Where the rolls 3852 and/or 3854 are heated, the
corrugations may comprise melt additive bloom areas 3790. The melt
additive bloom areas 3790 may be disposed in the distal ends 3754
of the corrugations. Additionally, the melt additive bloom areas
3790 may extend along the sidewalls 3756 as well. In some forms,
the melt additive bloom area 3790 may extend the entirety of the
sidewalls 3756. In some forms, the material web 100 may be utilized
as a topsheet of an absorbent article. In such forms, where the
distal ends 3754 are oriented in the positive Z-direction, the melt
additive bloom areas 3790 may comprise a hydrophobic melt additive.
In such forms, the hydrophobic melt additive may provide good
masking of liquid insults. Additionally, in such forms, the
hydrophobic melt additive may reduce the likelihood of rewet by
liquid insults. Where the distal ends 3754 are oriented toward an
absorbent core of the disposable absorbent article, the melt
additive bloom areas 3790 may comprise a hydrophilic composition.
In such forms, the hydrophilic composition can improve liquid
acquisition.
[0215] Instead of rolls, plates may be utilized to create the
corrugations 3770. In such forms, teeth of one or more of the
plates may be heated such that at least a portion of the
corrugation may be provided with a corresponding melt additive
bloom area 3790. Processes for forming the corrugations 3770 are
discussed in additional detail in U.S. Patent Application
Publication No. 2004/0137200.
Fusion Bonds
[0216] Still another exemplary process which may be utilized as a
first unit operation 140 (shown in FIG. 2) is a process that can
provide fusion bonding to an absorbent article. The distinction
between embossments (discussed with regard to FIGS. 4A and 4B) and
fusion bonding is that generally, embossing does not result in the
fusion of layers.
[0217] FIGS. 8A and 8B show an exemplary bonding apparatus 800 that
may be used to bond the precursor material 102 and a second
substrate 104 together to form the material web 100. The bonding
apparatus 800 may include a bonding roll 806 adapted to rotate
around an axis of rotation 808, and an anvil roll 810 adapted to
rotate around an axis of rotation 812. The anvil roll 810 includes
an outer circumferential surface 814 which is preferably smooth.
Bonding roll 806 includes a base circumferential surface 820, from
which one or more bonding elements, or nubs 816 extend. The bonding
roll 806 is adjacent the anvil roll 810 so as to define a nip 826
between the bonding roll 806 and the anvil roll 810, and more
particularly, to define the nip 826 between the bonding surface of
each nub 816 and the anvil roll 810. It is to be appreciated that
the bonding roll 806 and the anvil roll 810 may be configured to
rotate such that the bonding surfaces on the bonding roll 806 and
the outer circumferential surface 814 of the anvil roll 810 move at
the same speeds or different speeds.
[0218] During the bonding operation, the bonding roll 806 may
rotate in a first direction 828 around the axis of rotation 808 of
the bonding roll 806, and the anvil roll 810 may rotate in a second
direction 830, opposite the first direction 828, around the axis of
rotation 812 of the anvil roll 810. The precursor material 102 and
second substrate 104 may advance in a machine direction MD between
the bonding roll 806 and the anvil roll 810. As shown, the
precursor material 102 includes a first surface 832 and a second
surface 834 opposite the first surface 832, and the second
substrate 104 includes a first surface 836 and a second surface 838
opposite the first surface 836. As such, the first surface 832 of
the precursor material 102 is contacted by the bonding roll 806,
and the second surface 838 of the second substrate 104 is contacted
by the anvil roll 810. And the second surface 834 of the precursor
material 102 and the first surface 836 of the second substrate 104
contact each other. As the precursor material 102 and second
substrate 104 advance through the nip 826 between the bonding
surface of a nub 816 and the anvil roll 810, the nub 816 contacts
the precursor material 102 and compresses the precursor material
102 and second substrate 104 between the bonding surface of the nub
816 and the anvil roll 810. In turn, heat generated by the nip
pressure causes the precursor material 102 and second substrate
material to yield. The bonding surface of the nubs 816 presses
yielded material of the precursor material 102 and second substrate
104 together to form a plurality of discrete bond sites 842 between
the precursor material 102 and second substrate 104. Thus, the
apparatus 800 may form the material web 100 which includes the
precursor material 102 and the second substrate 104 bonded together
by discrete bond sites 842, without the use of adhesives. It is to
be appreciated, however, that the bonding apparatus 800 may also be
used in combination with adhesives. Although FIG. 8A shows the
apparatus 800 bonding two substrates together, it is to be
appreciated that the apparatus may bond more than two substrates
together. In addition, it is to be appreciated that the apparatus
800 may also be used to bond fibers of nonwoven together on a
single substrate. The anvil roll and bonding roll may or may not be
heated. Additionally, forms of the present invention are
contemplated where the precursor material 102 is fed to the nip 826
of the apparatus 800 in place of the second substrate 104 and the
second substrate 104 is fed to the nip 826 of the apparatus 800 in
place of the precursor material 102.
[0219] As shown in FIG. 8C, the material web 100 may comprise a
plurality of discrete bond sites 842 which bond the precursor
material 102 to the second substrate 104. In some forms of the
present invention, the bonding roll 806 (shown in FIG. 8A) and/or
the forming elements 816 (shown in FIG. 8A) thereof may be heated.
In such forms, the resultant material web 100 may comprise melt
additive bloom areas 890. The melt additive bloom areas 890 are
exaggerated for ease of explanation.
[0220] As shown, the melt additive bloom areas 890 may be provided
in a distal end 854 of the discrete bond site 842 and on a portion
of sidewalls 856 of the discrete bond sites 842. In such forms, the
melt additive bloom areas 890 may comprise a hydrophobic
composition. Where the material web 100 is utilized as a topsheet
of a disposable absorbent article, the hydrophobic composition of
disposed in the discrete bond sites 842 can reduce the likelihood
that liquid insults stay in the bond site 842. As such, the
hydrophobic composition can help provide a cleaner looking article
even post liquid insult.
[0221] The utilization of discrete bond sites 842 may be done in
conjunction with apertures, embossments, outer tufts, tunnel tufts,
nested tufts, and/or corrugations described herein.
Distal End/Land Area Bonds
[0222] Still another exemplary process which may be utilized as a
first unit operation 140 (shown in FIG. 2) is a process that can
provide fusion bonds on the distal ends of tufts (including tunnel,
nested, outer), on land areas adjacent the tufts, on ridges and on
grooves. The localized fusion bonding of these discontinuities can
provide for melt additive bloom areas where the fusion bonds
occur.
[0223] FIG. 9A shows an apparatus 900 for deforming the material
web which includes an additional bonding roll 950 for bonding the
distal ends (554 shown in FIGS. 5B, 5C and 5G-5J; 654 shown in
FIGS. 6G-6I, 6O and 6P). As shown, the precursor web 102 is fed
into a deforming nip 906 between first roll 902 and second roll
904. After leaving the deforming nip 906, the deformed precursor
web 102' is wrapped partially around the first roll 902. Vacuum,
hold down belts, or some other mechanism may be used to keep the
deformed precursor web 102' seated on the first roll 902. While the
deformed precursor web 102' is still in contact with the first roll
902, the deformed precursor web 102' passes through a second nip
956 between first roll 902 and the additional bonding roll 950. The
additional bonding roll 950 can compress the fibers at the distal
ends 554 and 654 of the tufts 530, 570, 572 (shown in FIGS. 5B, 5C
and 5G-5J) and tufts 632 (shown in FIGS. 6G-6I, 6O and 6P)
sufficient to partially melt and bond the fibers at this location
together. The bonding roll 950 may be heated to help facilitate
bonding. Alternatively, ultrasonics could be used to facilitate
bonding. In the case of at least some of the precursor materials
described herein, the materials can be bonded together if the
bonding roll 950 surface temperature is between about 120.degree.
F. (about 50.degree. C.) and about 270.degree. F. (about
130.degree. C.). Upon exit of the second nip 956, the material web
may wrap the bonding roll 950 as shown in FIG. 28, or it may wrap
the first roll 902.
[0224] Referring to FIGS. 5A-5J and 9A, in some forms, the first
roll 902 may be configured as described heretofore with regard to
roll 504. As noted above, with the addition of heat to the bonding
roll 950, the first roll 902 and/or second roll 904 may not need to
be heated to provide a melt additive bloom area at the distal ends
554 of the tufts 530, 570, or 572.
[0225] Referring to FIGS. 6A-6P and 9A, in some forms, the first
roll 902 may be configured as described heretofore with regard to
roll 602. As noted above, with the addition of heat to the bonding
roll 950, the first roll 902 and/or second roll 904 may not need to
be heated to provide a melt additive bloom area at the distal ends
654 of the tufts 632.
[0226] As shown in 9B, the process of FIG. 9A produces a tuft in
which the layers are bonded together at the tops (or distal ends
954) of the tufts 970. With the above in mind, tufts 970 may be
configured as described heretofore with regard to the tufts 530,
570, 572 (shown in FIGS. 5A-5J) or tufts 632 (shown in FIGS.
6A-6P). The process described in FIG. 9B will form a tip bonded
portion 952. The tip bonded portion 952 will often differ in at
least one of: size (that is, they may be larger), shape, and
location from any thermal point bonds present in spunbonded
nonwoven layers. The tip bonded portion 952 will typically be
registered with the tuft 970 in the material web 100, while thermal
point bonds may be provided in a separate and different pattern.
The tip bonding may result in a more translucent (film-like) bonded
portion 952. Placing a layer containing color adjacent to the tuft
970 could result in color showing through primarily in the
translucent bonded portion 952, highlighting the tuft 970. For
those forms where the material web 100 comprises a single layer or
integrated strata of nonwoven material, the tip bonded portion 952
may bond the constituent fibers of the material web 100 and may be
configured as described above.
[0227] As noted above, the bonding roll 950 may apply heat during
the bonding process. In such forms, a melt additive bloom area may
correspond to the tip bonded portion 952. Without wishing to be
bound by any particular theory, it is believed that bonding
material web 100 at the distal ends 954 of the tufts 970 may
provide benefits which include: 1) increased perception of the
depth of base openings 944 when the base openings 944 are oriented
toward the consumer, as well as 2) improved dryness (by reducing
the hang-up of fluid in the bottoms of the tufts 970 when the base
openings 944 are oriented toward the consumer); and 3) reduction or
elimination of the need to glue or otherwise bond the layers of a
dual or multilayer precursor web 102 together.
[0228] In other forms of the present invention, an apparatus may
bond the material web 100 adjacent the tufts 970--adjacent the base
50, 650 (shown in FIGS. 5B-5J and 6H, 6O, and 6P, respectively,
termed "base bonding". If the material web 100 is a single layer
material, then this step will bond the fibers of the material web
100 together adjacent the bases 50, 650. If the deformed material
web 100 is a dual or multiple layer nonwoven material, then this
step will bond the fibers of each layer together adjacent the base
50, 650 and will also bond fibers in each of the layers together
adjacent the base 50, 650.
[0229] Another exemplary process for the first unit operation 140
(shown in FIG. 2) is shown with regard to FIG. 10. An apparatus
1000 for deforming the material web 100 which includes an
additional bonding roll 1060 for base bonding the deformed material
web 100 is shown. The position of first and second rolls 902 and
904 from FIG. 9A are reversed. As shown, the precursor web 102 is
fed into the deforming nip 906 between first roll 902 and second
roll 904. After leaving the deforming nip 906, the deformed
precursor web 102' is wrapped partially around the second forming
roll 904. Vacuum, hold down belts, or some other mechanism could be
used to keep the deformed precursor web 102' seated on the second
roll 904. While the deformed precursor web 102' is still in contact
with the second roll 904, it passes through a second nip 966
between second roll 904 and the additional bonding roll 1060. The
additional bonding roll 1060 can compress the fibers in the
undeformed portions of the deformed precursor web 102' adjacent the
bases 50, 650 sufficient to partially melt and bond the fibers at
this location together. The bonding roll 1060 may be heated to
facilitate bonding in the case of at least some of the precursor
materials described herein. Ultrasonics may also be used to
facilitate bonding. Upon exit of the second nip 966, the material
web may wrap the bonding roll 1060 as shown in 10A, or it may wrap
the second roll 904.
[0230] There are a number of variations of the roll configurations
in the bonding step. The surface of the bonding roll 1060 may be
substantially smooth or may comprise a plurality of bonding
elements 1064. Similarly, the second roll 904 may comprise a smooth
surface or may comprise a plurality of bonding elements 1062 (shown
in FIGS. 13A and 13B).
[0231] Referring to FIGS. 11A and 11B, in those cases in which the
surface of the bonding roll 1060 is substantially smooth, base bond
portions 1068 may be at least substantially continuous and may
substantially or completely surround the base opening 944 in the
material web 100. FIG. 11A shows the material web 100 having
continuous base bond sites 168. FIG. 11B is a cross-section of the
material web 100 shown in FIG. 11A.
[0232] As shown in FIG. 12, in those cases in which the bonding
roll 1060 or the second roll 904 have a plurality of discrete,
spaced-apart bonding elements 1062 and 1064, respectively,
protruding from their surfaces, the bonding elements will only bond
discrete, spaced-apart regions of the material web 100 in adjacent
the base 50 outside of the openings 944 and/or tufts 970. In such
cases, the base bond portions 1068 may be located in at least two
discrete portions of the material web 100 which are adjacent to but
lie outside of at least some of the tufts 970. In other words, in
such cases there may be at least two base bond portions 1068 for a
given tuft 970.
[0233] Referring to FIGS. 10, and 13A-13C, the bonding roll 1060
can have a plurality of discrete, spaced-apart bonding elements
1062 protruding from its surface as shown in FIG. 13C. In some
forms, particularly with regard to nested tufts disclosed herein,
the second roll 904 may be configured similarly to the roll 502
(shown in FIG. 5A) or female roll 604 (shown in FIG. 6A). In some
forms, portions of the surface 1024 of the second roll 904 that are
located outside of the recesses 1014 in the second roll 904 may
also be substantially smooth, or they may have a plurality of
discrete, spaced-apart bonding elements 1064 protruding from the
surface 1024. The bonding elements 1064 on the surface 1024 of the
female roll 904 may be discrete, spaced-apart bonding elements 1064
as shown in FIG. 13A, or they may be continuous bonding elements
1064 as shown in FIG. 13B.
[0234] As noted above, the bonding roll 1060 may apply heat during
the bonding process. In such forms, a melt additive bloom area may
correspond to the base bond portions 1068. In such forms, the melt
additive bloom areas may be disposed adjacent the base opening 944
about the tuft 970. And, the melt additive bloom areas may comprise
a plurality of discrete portions or may be continuous as shown in
FIG. 11A.
[0235] Still another apparatus for use as the first unit operation
140 (shown in FIG. 2) is provided with regard to FIG. 14. The
apparatus 1100 is shown which can provide--referring back to FIGS.
9A and 11A-11B--both tip bonded portions 952 and base bonded
portions 1068. As shown the apparatus 1100 may comprise rolls 902,
904, and 950 which comprise the tip bonding portion of the
apparatus 1100, which is similar to the apparatus shown in FIG. 9A.
FIG. 14 differs in that the precursor web 102 is shown as being fed
into the deforming nip 906 from the right side in FIG. 14, instead
of the left side, and the deformed precursor web 102' wraps around
first roll 902 instead of bonding roll 950 after it leaves the
deforming nip 906. Therefore, the description of this portion of
the apparatus will incorporate the above description of the
apparatus shown in FIG. 9A, and will not be repeated in its
entirety herein.
[0236] The apparatus shown in FIG. 14 further comprises a second
roll 904' and a base bonding roll 1060. The first roll 902, the
second roll 904', and the base bonding roll 1060 comprise the base
bonding portion of the apparatus, which is similar to the apparatus
shown in FIG. 10. FIG. 14 differs in that the deformed precursor
web 102' is shown as wrapping around the second roll 904' as it
leaves the apparatus in FIG. 14, instead of wrapping around the
base bonding roll 1060. Therefore, the description of this portion
of the apparatus will incorporate the above description of the
apparatus shown in FIG. 10, and will not be repeated in its
entirety herein.
[0237] As shown in FIG. 14, the precursor web 102 is fed into the
deforming nip 906 between first forming roll 902 and second roll
904. After leaving the deforming nip 906, the deformed precursor
web 102' is wrapped partially around the first roll 902. While the
web 102' is still in contact with the first roll 902, it passes
through a second nip 956 between first roll 902 and the additional
bonding roll 950. The additional bonding roll 950 can compress the
fibers at the distal ends 954 of the tufts 970 sufficient to
partially melt and bond the fibers at this location together. Heat
and/or ultrasonics may also be used to help facilitate bonding. As
shown in FIG. 9B, this produces the tuft 970 in which the
constituent material is bonded together at the tops (or distal ends
954) of the tufts 970. The deformed tip bonded web 102' then passes
between first roll 902 and second female roll 904'. After that, the
deformed tip bonded web 102' is wrapped partially around the second
female roll 904'. While the web 102' is still in contact with the
second female roll 904', it passes through a second nip 966 between
the second female roll 904' and the additional bonding roll 1060.
The additional bonding roll 1060 can compress the fibers adjacent
the bases 50 of the tufts 970 sufficient to partially melt and bond
the fibers at this location together. Heat and/or ultrasonics may
also be used to help facilitate bonding. This will provide the tip
bonded web with base bonds 1068 which may be continuous as shown in
FIG. 11A, or discrete as shown in FIG. 12.
[0238] Referring back to FIGS. 9A-14, the addition of heat to the
rolls described above can provide melt additive bloom areas which
correspond to the tip bond 952 and/or the base bonds 1068. In some
forms, the melt additive bloom areas may comprise a hydrophobic
composition and may correlate to the tip bonds 952. In such forms,
particularly where the material web 100 comprises a topsheet of an
absorbent article and where the distal ends 954 of the tufts are
facing toward a user, the hydrophobic composition can provide
masking of liquid insults to an absorbent article. In other forms,
where the material web 100 comprises a topsheet of an absorbent
article and where the distal ends 954 are facing away from a user,
the melt additive bloom areas may comprise a hydrophilic
composition. In such forms, the hydrophilic composition can reduce
the liquid insult acquisition time.
Additional Processes
[0239] Still other examples of first unit operations 140 (shown in
FIG. 2) comprise infrared heating and/or ultrasonic heating. With
such forms, portions of the material web 100 for which no melt
additive bloom area is desired would require shielding of some
kind, e.g. reflective foil or protective mask. However, forms of
the present invention are contemplated where the infrared heating
is applied via a laser or a plurality thereof. Such forms may
obviate the need for shielding since the thermal energy provided by
infrared laser can be applied with a high degree of accuracy to the
material web 100. As such, any suitable pattern of melt additive
bloom areas may be provided.
[0240] As an example, a material web that is apertured can be
exposed to ultrasonic and/or laser energy. In such forms, melt
additive bloom areas may be provided over the majority of the
material web with the exception of the apertures. Such forms, may
be useful as a topsheet of a disposable absorbent article,
particularly when the melt additive bloom areas comprise a
hydrophobic composition. In other forms, a material web may
comprise one or more of the discontinuities described herein,
apertures, embossments, tunnel tufts, outer tufts, filled tufts,
nested tufts, ridges, grooves, etc. In such forms, the material web
may be exposed to ultrasonic and/or laser energy. In such forms,
melt additive bloom areas may be provided over the majority of the
material web with the exception of the apertures. Where the
material web is utilized as a topsheet of a disposable absorbent
article, the melt additive bloom areas may comprise a hydrophobic
composition. Such forms, may be useful in reducing the likelihood
of rewet while the addition of apertures can allow for adequate
liquid acquisition time.
[0241] Additionally, forms are contemplated, as discussed
previously, where the material web comprises multiple layers or
strata. In such forms, an upper layer or strata may comprise a
hydrophobic melt additive while a subjacent layer or strata may
comprise a hydrophilic melt additive. In such forms, the
application of ultrasonic and/or laser energy to the material web,
can provide disparate melt additive bloom areas in the upper layer
or strata versus the lower layer or strata. In such forms, the
discontinuities comprising tufts, e.g. outer tufts, tunnel tufts,
filled tufts, nested tufts, corrugations may provide good reduction
in the likelihood of rewet while also providing good liquid
acquisition properties.
[0242] Another example of a process which can be utilized in the
first unit operation 140 (shown in FIG. 2) is a hot air knife.
Referring to FIG. 21, hot air knifes may be utilized to provide a
plurality of melt additive bloom areas 2190 to the material web
100. As shown, an apparatus 2100 comprising a header 2112 which is
supplied with hot air through an inlet. The hot air supplied to the
header 2112 may have a temperature of about 200-550.degree. F.,
more generally about 250-450.degree. F., most commonly about
300-350.degree. F. The optimum temperature will vary according to
the polymer type, basis weight and line speed of the material web
100 traveling beneath the apparatus 2100. For a polypropylene
spunbond web having a basis weight of about 0.5-1.5 osy, and
traveling at a line speed of about 1000-1500 feet per minute, a hot
air temperature of about 300-350.degree. F. is desirable.
Generally, the hot air temperature should be at or near (e.g.,
slightly above) the melting temperature of the material being
bonded.
[0243] The air flow rate may be controlled by controlling the
pressure inside the header 2112. The air pressure inside the header
12 is between about 1-12 inches of water (2-22 mm Hg) or between
about 4-10 inches of water (8-18 mm Hg). The volume of hot air
required to effect the desired level of inter-fiber bonding may be
reduced by increasing the temperature of the hot air.
[0244] Extending from the header 2112 are three spaced apart hot
air conduits 2124, 2126, and 2128. The conduits may be rigid or
flexible, but are preferably made of a flexible material in order
to permit adjustment and/or movement. The conduits are each
connected at one end to the header 2112, and are connected at their
other ends to a plenum/hot air knife slot 2134, 2136, and 2138. Hot
air from the header 2112 is preferably supplied at roughly equal
volume and velocity to each of the conduits 2124, 2126, and 2128.
This equal division of flow can be accomplished in simple fashion,
by ensuring that the conduits are of equal dimensions and size and
that the air pressure is uniform at the entrances to the conduits.
On the other hand, if a particular application warranted feeding
more or less air into some of the conduits than the others,
different flow rates can be accomplished by individually valving
the conduits, by designing them with different sizes, or by valving
the plenums.
[0245] As the precursor web 102 passes under the plenum/hot air
knife slots 2134, 2136, and 2138, a stream of heated air at a very
high flow rate, generally from about 1000 to about 10000 feet per
minute (fpm) (305 to 3050 meters per minute), is directed at the
precursor web 102. As noted above, the air is heated to a
temperature insufficient to melt the polymer in the precursor web
102 but sufficient to soften it slightly. The focused stream of air
is arranged and directed by at least one slot of about 3 to 25 mm
in width, particularly about 9.4 mm, serving as the exit for the
heated air towards the precursor web 102.
[0246] The application of heated air to the precursor web 102 as
described above can increase bonding between constituent fibers of
the precursor web 102--for those forms where the precursor web 102
is a nonwoven. Additionally, the application of heated air to the
precursor web 102 can provide the material web 100 with a plurality
of melt additive bloom sites 2190. The melt additive bloom sites
2190 may correspond to the width of the hot air knife slots which
discharge the hot air that impacts the precursor web 102. As shown,
the melt additive bloom areas 2190 may be provided to the material
web 100 in a plurality of stripes. Forms of the present invention
are contemplated where one or more hot air knife slots are provided
which span the entire width of the precursor web 102 in the CD. In
such forms, the melt additive bloom areas provided to the material
web 100 may be across the width of the material web 100 in the
CD.
[0247] Additional details regarding the use of hot air knifes is
provided in U.S. Pat. Nos. 5,707,468 and 6,066,221.
Thermal Energy Application across the entire Web
[0248] In contrast to the aforementioned processes which can create
discrete melt additive bloom areas, as noted previously, in some
forms, it may be beneficial to provide melt additive bloom areas
across the entirety the material web. In such forms, any suitable
method of thermal energy application may be utilized.
[0249] Some examples include the use of microwave (radio frequency)
radiation. This approach is particularly powerful if a salt
solution (e.g. potassium acetate in poly ethylene glycol) has been
sprayed onto the surface of the material web. The radiation will
then let the ions of the salt vibrate, which causes friction, which
causes heat. Ultrasonic may also be used alternatively. In one
specific example, if hydrophobic melt additives are used to make
carded nonwovens, the heat exposure of the carding process can be
leveraged (hot air oven of 160.degree. C. at a comparably long
contact time of 1-2 s).
[0250] And, combining both on-line heating and tempering can
synergistically increase the effect. An optimized heat activation
step (highly effective in line heat insertion, e.g. via IR dryer)
can be translated into further usage reduction and/or better
performance.
[0251] The heat application of the aforementioned processes may be
applied as part of the making process, directly after spinning of
the fibers and laydown of the web--as part of the bonding process
(via a heated calendar) or a subsequent step (e.g. drum dryer or,
most effectively, infrared heater). In this case typically high
temperatures can be applied. An exposure in the seconds or even
mili seconds range may be sufficient depending on the composition
of the material web. Additionally, the amount of thermal energy
required to promote melt additive blooming depends on whether the
application of thermal energy is performed within a short period of
time after formation of the material web. For material webs which
are subjected to thermal energy application immediately subsequent
to production, a lower amount of thermal energy may be required to
promote melt additive blooming as opposed to material webs which
were not subjected to thermal energy application subsequent to
formation.
[0252] Alternatively the heat activation can be done via tempering
of the final material web over several days, e.g. 30 days. It has
been found that for the Techmer glycerol tristearate Masterbatch
that the temperature window for such tempering can be between about
30 to less than about 52.degree. C. (as of 52.degree. C. the
glycerol tristearate fibrils will melt again) between about
32.degree. C. to about 50.degree. C., between about 35.degree. C.
to about 47.degree. C., between about 37.degree. C. to about
45.degree. C., specifically including all values within these
ranges and any ranges created thereby. In some forms, a temperature
of 37.degree. C. Tempering can be done with fresh samples (not more
than a few hours after making). Older samples may require
additional thermal energy input.
Melt Additive Bloom Areas
[0253] Referring to back FIG. 1, as stated previously, the
precursor web 102 and therefore the material web 100 of the present
invention comprise a melt additive. And as described herein, with
the appropriate application of heat to the precursor web 102 and/or
material web 100, one or more melt additive bloom areas may be
provided to the material web 100. The melt additive bloom areas
described herein may be in the form of a film, flakes, fibrils, or
combinations thereof. For example, where the material web 100
comprises a nonwoven material, the melt additive bloom areas can
bloom to the surface of the filaments of the nonwoven and create a
film covering a portion of the external surface of the filament
and/or can create fibrils, flakes, particles, and/or other surface
features. Some examples of fibrils, flakes and films are provided
with regard to FIGS. 28A-29B.
[0254] However, the inventors have also found that care must be
taken when processing material webs particularly when discrete melt
additive bloom areas are desired. Many nonwoven webs are calendar
bonded to provide strength in the CD. The calendar bonding process
is often a heated process which adds thermal energy to the web as
it is bonded. Subsequently, the web is often rolled up for storage.
But, such storage provides insulation for the thermal energy from
the calendar bonding process. So, instead of melt additive bloom
areas that are discrete, these webs often have melt additive boom
areas well outside of the areas of applied localized thermal
energy. Other processes which impart thermal energy to the material
web may experience the same type of effect is rolled and stored. To
counteract such heat diffusion in the material web, when not
desired, chilled rolls may be utilized to cool the material web
after the calendar bonding process or other thermal processes. Each
of Examples 2-4 demonstrate this aspect of material webs which
comprise melt additives and are subjected to calendar bonding.
[0255] The above phenomena can be even more prevalent in
bi-component fibers/filaments. For example, where melt additive is
provided in the sheath of sheath-core bi-component
fibers/filaments, the diffusion length for the melt additive in the
sheath will be shorter than the diffusion length for mono-component
fibers. This phenomena is demonstrated with Examples 35 and 36
below. Each of these webs was subjected to calendar bonding and
subsequently would up.
EXAMPLES
[0256] Exemplary material webs in accordance with the present
disclosure were produced. The material webs were dual layer
constructions. The upper layer was 25 gsm polypropylene
1/polypropylene 2 ("PP.sub.1/PP.sub.2") crimped fiber spun bond
comprising a hydrophobic melt additive which was 16 percent by
weight glycerol tristearate master batch (Techmer PPM15000) in both
polypropylene components. The lower layer was 25 gsm
PP.sub.1/PP.sub.2 crimped fiber spun bond comprising 0.4 percent by
weight topical surfactant Silastol PHP26. The two layers were
overbonded together (see FIGS. 3A and 3B) in a center zone and then
stretched (see FIGS. 3A and 3C) to create apertures in the center
and tufts on the sides. The upper and lower layers were then fusion
bonded to secondary topsheet, thereby forming a laminate. The
images shown in FIGS. 28A-29B are of the unmodified fibers in the
upper layer (wrinkled surface), fusion bond sites (showing fibrils)
and melt lips around the apertures (also showing fibrils). The
presence of fibrils implies a higher concentration of the
hydrophobic melt additive of the first layer at the surface.
[0257] As shown in FIG. 28A, a low magnification plan view image of
the above laminate. The image shows melt lips 2820 of the
apertures, fusion bond sites 2810, and the upper and lower layer
bond sites. FIG. 28B is a higher magnification of the same
laminate. As shown in FIG. 28B, the fusion bond sites demonstrate
fibrils (thread like elements shown in FIG. 28B) formed by the
hydrophobic melt additive. FIG. 28C, shows that the melt lips of
the apertures similarly comprise fibrils from the hydrophobic melt
additive. FIG. 28D is a higher resolution image of the melt lips.
Referring to FIGS. 29A and 29B, the fibers of the upper layer did
not comprise fibrils outside of the melt lips and fusion bonds.
[0258] The melt additive may form between about 0.5 percent by
weight to about 10 percent by weight of the material web 100. In
some forms, the melt additives may be less than about 10 percent by
weight, less, less than about 8 percent by weight, less than about
5 percent by weight, less than about 2.5 percent by weight,
specifically including any values within these ranges or any ranges
created thereby. In some forms, the melt additive may be about 6
percent by weight of a master batch containing 40 percent by weight
of the melt additive. In some forms, the melt additive may form
between about 0.5 percent by weight to about 6 percent by weight of
the master batch or from about less than 4 percent by weight of the
master batch or any value within these ranges and any ranges
created thereby.
[0259] The inventors have found that if the concentration of melt
additive by weight percent is too low, the melt additive bloom
areas provided with localized heat application may not be
sufficient to provide the desired functionality. In contrast, if
the melt additive concentration is too high, melt additive bloom
areas may occur without the localized heat application--auto
blooming. Without wishing to be bound by theory, it is believed
that the diffusion coefficient (explained in additional detail
below) of the melt additive increases with the concentration of
melt additive in the polymer matrix of the thermoplastic polymeric
material of the material web.
[0260] Without wishing to be bound by theory, it is believed that
the glass transition temperature of the polymer which makes up the
material of the web, the molecular weight of the melt additive, as
well as the chain length of the melt additive impacts the blooming
capability of the melt additive. It is believed that where the
polymer is in its glassy state, the glassy state of the polymer
matrix can "lock away" the melt additive and discourage
blooming.
[0261] For those polymers which comprise a high Tg, e.g.
polystyrene--100 degrees C.; polycarbonate--145 degrees C.--the
melt additives that can be utilized may be more extensive than for
those polymers with lower glass transition temperatures. For those
polymers with lower Tg's, e.g. polypropylene, polyethylene, the
melt additives which can be utilized are limited to some extent.
With lower Tg's of the thermoplastic polymeric material, some melt
additives may auto bloom at room temperature.
[0262] For those polymers with a high Tg, any suitable melt
additive may be utilized. Some examples of suitable hydrophobic
melt additives include fatty acids and fatty acid derivatives. The
fatty acids may originate from vegetable, animal, and/or synthetic
sources. Some fatty acids may range from a C8 fatty acid to a C30
fatty acid, or from a C12 fatty acid to a C22 fatty acid. In other
forms, a substantially saturated fatty acid may be used,
particularly when saturation arises as a result of hydrogenation of
fatty acid precursor. Examples of fatty acid derivatives include
fatty alcohols, fatty acid esters, and fatty acid amides. Suitable
fatty alcohols (R--OH) include those derived from C12-C30 fatty
acids.
[0263] Suitable fatty acid esters include those fatty acid esters
derived from a mixture of C12-C30 fatty acids and short chain
(C1-C8, preferably C1-C3) monohydric alcohols preferably from a
mixture of C12-C22 saturated fatty acids and short chain (C1-C8,
preferably C1-C3) monohydric alcohols. The hydrophobic melt
additive may comprise a mixture of mono, di, and/or tri-fatty acid
esters. An example includes fatty acid ester with glycerol as the
backbone as illustrated in [1].
##STR00001##
where R1, R2, and R3 each is an alkyl ester having carbon atoms
ranging from 11 to 29. In some forms, the glycerol derived fatty
acid ester has at least one alkyl chain, at least two, or three
chains to a glycerol, to form a mono, di, or triglyceride. Suitable
examples of triglycerides include glycerol thibehenate, glycerol
tristearate, glycerol tripalmitate, and glycerol trimyristate, and
mixtures thereof. In the case of triglycerides and diglycerides,
the alkyl chains could be the same length, or different length.
Example includes a triglyceride with one alkyl C18 chain and two
C16 alkyl chain, or two C18 alkyl chains and one C16 chain.
Preferred triglycerides include alkyl chains derived from C14-C22
fatty acids.
[0264] Suitable fatty acid amides include those derives from a
mixture of C12-C28 fatty acids (saturated or unsaturated) and
primary or secondary amines. A suitable example of a primary fatty
acid amide includes those derived from a fatty acid and ammonia as
illustrated in [2].
##STR00002##
where R has a number of carbon atoms ranging from 11 to 27. In at
least one other form, the fatty acids may range from a C16 fatty
acid to a C22 fatty acid. Some suitable examples include erucamide,
oleamide and behanamide. Other suitable hydrophobic melt additives
include hydrophobic silicones, ethoxylated fatty alcohols.
Additional suitable hydrophobic melt additives are disclosed in
U.S. patent application Ser. No. 14/849,630 and U.S. patent
application Ser. No. 14/933,028. Another suitable hydrophobic melt
additive is available from Techmer PM in Clinton, Tenn. under the
trade name PPM17000 High Load Hydrophobic. One specific example of
a melt additive is glycerol tristearate.
[0265] Similarly, for those polymers with a high Tg, any suitable
hydrophilic additive can be used. Some suitable examples include
those available from Techmer PM, Clinton, Tenn. sold under the
trade name of Techmer PPM15560; TPM12713, PPM19913, PPM 19441,
PPM19914, (for polypropylene), and PM19668 (for polyethylene).
Additional examples are available from Polyvel Inc. located in
Hammonton, N.J., sold under the trade name of Polyvel VW351 PP
Wetting Agent; from Goulston Technologies Inc. located in Monroe,
N.C. sold under the trade name Hydrosorb 1001; as well as those
hydrophilic additives disclosed in US Patent Application
Publication No. 2012/0077886 and U.S. Pat. Nos. 5,969,026 and
4,578,414. Other suitable hydrophilic melt additives are Unithox
720 and Unithox 750 and Techsurf 15560 from Techmer in general.
[0266] For those polymers with a lower glass transition
temperature, e.g. polypropylene, polyethylene, the list of
available melt additives may be much more restrictive assuming that
the desired outcome is to discourage auto blooming. Note, that the
discouragement of auto blooming does not necessarily coincide with
the preclusion of auto blooming. Without wishing to be bound by
theory, it is believed that for those polymers with a lower Tg, the
chain length and molecular weight of the melt additives become much
more critical in whether auto blooming will occur. It is believed
that for those melt additive compositions having a higher
chain-length and a higher molecular weight, a lower diffusion
coefficient in the polymer exists at room temperature. So, it is
believed that for higher chain length melt additive compositions,
auto blooming will be discouraged at room temperature, e.g. about
25 degrees C.
[0267] Some suitable examples of hydrophobic melt additives
suitable for use in conjunction with polypropylene and/or
polyethylene is glycerol tristearate. As used herein, glycerol
tristearate is defined as a mixture of long-chained triglycerides
containing predominately C18 and C16 saturated alkyl chain lengths.
Additionally, there could be varying degrees of unsaturation and
cis to trans unsaturated bond configurations. The alkyl chain
lengths could range from about C10 to about C22. The degrees of
unsaturation typically will range from 0 to about 3 double bonds
per alkyl chain. The ratio of cis to trans unsaturated bond
configurations can range from about 1:100 to about 100:1. Other
suitable examples for use with polypropylene and/or polyethylene, a
triglyceride which contains either stearic acid or palmic acid or
both as the fatty acid components, or a mixture of such
triglycerides.
[0268] In one specific example, polypropylene fibers which were
spun from a mixture of the resin Polypropylene Moplen HP561R and 6
percent by weight glycerol tristearate Masterbatch (containing 40
percent by weight of the melt additive) from Techmer, processed at
a temperature of 250.degree. C. with a residence time of 9 minutes
in the extruder showed no blooming at room temperature.
[0269] An exemplary hydrophilic melt additive which can be utilized
in combination with polypropylene and/or polyethylene is Polyvel
surfactant S-1416. It is believed that homologues with a higher
molecular weight than Polyvel surfactant S-1416 in a polypropylene
or polyethylene matrix may also be utilized.
[0270] The Polyvel S-1416 is a silicon surfactant with a
(hydrophilic) poly ethylene oxide (PEO) chain and molecular weight
above 700 g/mol. Polyvel S-1416 is available from Polyvel Inc. and
is also known under the trade name "VW351." Without wishing to be
bound by theory, it is believed that the "resistance to blooming"
is controlled via the length of the PEO chain. Namely, it is
believed that the longer the PEO chain, the larger the resistance
to blooming. S-1416 has a chain of 10 or 11 ethylene oxide repeat
units. Additionally, activation of S-1416 requires besides heating
a humid environment (e.g. 80% relative humidity or in the presence
of water sprayed onto the surface). It further believed that under
these conditions the hydrophilic tail is flipped outward.
[0271] For those forms of the present invention where auto-blooming
is desired, then the melt additive list provided with regard to the
higher Tg polymers may be utilized in conjunction with polymers
having a lower Tg, e.g. polypropylene and/or polyethylene. And, in
such instances, the application of heat to the material web as
described herein can enhance the blooming of the melt additive,
namely increasing the amount of melt additive which blooms to the
surface. In contrast, for those forms of the present invention
where the discouragement of auto blooming is desired, then the
thermoplastic polymeric material and the melt additive may be
matched as described herein such that auto blooming of the melt
additive is discouraged.
[0272] For those forms where the material web 100 (shown in FIG. 1)
comprises a hydrophobic melt additive, the material web 100 may be
incorporated into a disposable absorbent article as a topsheet or
overwrap in the case of a tampon. While conventional wisdom would
typically advise against a hydrophobic topsheet, nonwoven webs of
the present invention may comprise apertures which allow for rapid
acquisition of liquid insults. In such forms, hydrophobic topsheets
can provide a clean dry surface against a wearer's skin.
Additionally, the hydrophobic treatment in the first plurality of
filaments may reduce liquid rewet.
[0273] And, while conventional wisdom may promote post filament
production enhancement of hydrophobicity/hydrophilicity, e.g.
topical application, applications of such compositions may be cause
additional strife. For example, many topically applied treatments
can migrate to other structures within an absorbent article.
However, the inventors have surprisingly discovered that where
fibers being heat treated as described herein, the discrete melt
additive bloom areas do not migrate or migrate to a much lesser
extent than topically applied compositions. Migration of the melt
bloom areas is discussed in additional detail hereafter.
[0274] In some forms of the present invention, additional melt
additives are contemplated. For example, the melt additive may
comprise a composition which improves tactile sensation, e.g.
softness additive. A suitable example of an additive for softness
includes Erucamide which may be provided in amounts ranging from
about 0.1 to about 20 percent by weight. Additional suitable
additive may be provided with regard to reduction of coefficient of
friction, or the like. The melt additive which pertains to softness
may be beneficial for those forms of the present invention where
the material web 100 comprises a plurality of discontinuities
selected from outer tufts, tunnel tufts, filled tufts, nested
tufts, corrugations, and combinations thereof. While erucamide may
auto bloom when used in conjunction with polypropylene and/or
polyethylene, the erucamide which blooms to the surface can be
enhanced, particularly in the tufts (described herein) and/or
corrugations which in some forms may contact a user's skin. So for
example, heat application as described herein may enhance the
amount of erucamide that blooms in the distal ends of the tufts
and/or corrugations. Additional melt additives for softness that
are contemplated, include stereamide and oleamide or mixtures
thereof. In some forms, mixtures of erucamid, stereamide and/or
oleamide may be provided the melt additive.
[0275] In some forms, the melt additive bloom areas can be utilized
to improve the adhesion of ink and/or of glues to the material web.
For example melt additive bloom areas comprising hydrophilic
compositions can increase the surface energy of the material web at
the location of the melt additive bloom areas. The increased
surface energy can increase the adhesion of inks and glues. In
contrast, where the melt additive bloom areas comprise a
hydrophobic composition, the melt additive bloom areas may be
selected to occur where ink and/or glues will not be present. In
general, inks and/or glues tend to wash off of hydrophobic
compositions/substrates. In such forms, auto blooming may be
desired.
[0276] In some forms, the melt additive bloom areas can be utilized
to form anchoring points at which subsequent coupling of molecules
can provide additional functionality of the melt additive bloom
areas. For example the melt additive bloom areas may comprise a
composition comprising a functional group which can be used for
subsequent chemical reaction. The chemical reaction in the
subsequent step should be carried out under mild enough conditions
(e.g. low enough temperature, below the softening points of the
polymer and the melt additive) so that the material web and the
melt additive bloom areas are not damaged. The reaction can be any
nucleophilic addition reaction or nucleophilic substitution
reaction, e.g. with one reactant having hydroxyl groups and the
chemical bond formed being an ester. In one specific form, the melt
additive bloom may be utilized to improve the stability of other
topical applications. For example, soil release polymers that
wouldn't normally bind to polyolefins could bind to compositions in
melt additive bloom areas.
[0277] In another example, the melt additive can comprise a
carboxylic acid group (--COOH). This can be an anchoring point for
a molecule comprising a hydroxyl group (--OH) as a second molecule
which reacts with the carboxylic acid group to form an ester.
Reversely, the melt additive can comprise a hydroxyl group and the
second molecule can comprise a carboxylic acid group. The formation
of an ester bridge is only one out of numerous examples for the
formation of a chemical bond with one reactant being a carboxylic
acid or a carboxylic acid derivative. The person skilled in the art
will easily identify alternative routes. In the selection of the
reactants it is important that the reaction can be carried out
under mild enough conditions (e.g. low enough temperature, below
the softening points of the polymer and the melt additive) so that
the substrate and the patterned structure are not damaged. Also the
reactant used as melt additive should not or only to a negligible
degree decompose under the conditions of processing.
[0278] As discussed previously, the inventors have surprisingly
found that the melt additive bloom areas do not migrate to the same
extent as topically applied compositions. Without wishing to be
bound by theory, it is believed that the glass transition
temperature of the melt additive composition or the melt
temperature of the melt additive (whichever is higher) needs to be
above 40 degrees C. Additionally, it believed that the diffusion
coefficient plays an important part of whether a melt additive
blooms. The melt additive diffusion coefficient can be defined
as:
D e .times. f .times. f = x 2 2 .times. t ##EQU00001##
where Deff is the diffusion coefficient, x=radius of the fiber or
half caliper of the film, and t=storage time. In order for the melt
additive to stay within the polymer matrix of the material web (no
melt additive bloom areas sans the application of thermal energy),
the diffusion coefficient needs to fulfill the condition:
D e .times. f .times. f < x 2 6 .times. .times. years
##EQU00002##
at room temperature or
D e .times. f .times. f < x 2 1 .times. .times. year
##EQU00003##
at 40.degree. C., assuming that 0.5 years accelerate aging at
40.degree. C. is predictive of 3 years aging at room temperature
(25.degree. C.). With such low diffusion coefficients (10.sup.-18
m.sup.2/s at room temperature and 10.sup.-17 m.sup.2/s at
40.degree. C. for a fiber with 40 .mu.m diameter) the melt additive
is in practical terms immobile in the polymer matrix and does not
diffuse to the surface. After 3 years at room temperature or 0.5
years at 40.degree. C. the blooming to the surface outside the
defined zones is so limited (if it happens at all) that the melt
additive bloom areas provided by the application of thermal energy
are maintained with little to no migration.
[0279] It is believed that these low effective diffusion
coefficients ("locking the melt additive in the polymer matrix")
can be achieved by using melt additives in a polymer matrix with
(i) no non-glassy amorphous domains or (ii) large size melt
additives in a polymer matrix with a very limited portion of
non-glassy amorphous domains at temperatures up to 40.degree. C.
For case (i), the polymer matrix may for example, by a completely
amorphous polymer which is in its glassy state at an environmental
temperature of 40.degree. C. (i.e. Tg>40.degree. C.). For case
(ii), the polymer matrix may for example, be a semi-crystalline
polymer in which a large parts or all of the amorphous domains are
in the glassy state at 40.degree. C.
[0280] One example of a suitable polymer for use in the material
webs of the present invention is polypropylene. Polypropylene (PP)
can have two types of amorphous domains: type I and type II. Type I
can be influenced by adjacent crystalline domains and has a Tg of
.about.75.degree.. ("Influenced" means that one end of the chain is
still tied to the crystal.) The diffusion coefficient for melt
additives in these domains is close to zero below 75.degree. C.
Type II is uninfluenced by the crystalline domains and has a Tg of
.about.5.degree. C. At room temperature the melt additive is only
able to effectively migrate in these uninfluenced amorphous domains
(Tg.about.5.degree. C.). Dependent on the portion and size of the
available Type II amorphous domains, the melt additive may not be
able anymore to effectively migrate in the polymer matrix,
particularly if the melt additive molecules are large and bulky. In
undrawn fibers, the crystals are of the form of spherulites with
sufficient uninfluenced amorphous domains around. In drawn fibers
(rapid cooling with rate of 2000 K/s plus stretching), fibrillous
crystals form with less and smaller amorphous domains around. Large
melt additives, e.g. molecular weight of GTS=891.5 g/mol, entrapped
in such structure are kinetically hindered from diffusion.
[0281] With the processes described herein, it is believed that the
application of heat during processing can increase the diffusion
coefficient into the range of:
D e .times. f .times. f > x 2 48 .times. .times. h
##EQU00004##
[0282] Achieving the above diffusion coefficient, the melt additive
is able to bloom to the surface of the material web in the areas of
thermal energy application with an optional post-processing curing
period of up to 24 hours. If the effective diffusion coefficient of
the melt additive in the polymer matrix is, for example, changed to
10.sup.-13 m.sup.2/s due to the application of thermal energy, the
melt additive bloom areas may occur within 30 min for a fiber with
40 .mu.m diameter. It is believed that the increase of the
diffusion coefficient with the application of thermal energy is
caused by a local change of the micro-structure of the host polymer
upon application. For smaller diameter fibers, the melt additive
bloom areas may occur even quicker than 30 minutes.
[0283] Some specific examples regarding thermal energy application
across the entirety of a material web are provided below.
Examples 1-4
[0284] Spunbonded (S) single layer nonwoven fabrics were produced
from 100-x wt % Ziegler-Natta polypropylene and X wt % of a
hydrophobic melt additive (PPM17000 High Load Hydrophobic) and were
thermally bonded. Each of the single S-layers had a weight of 20
g/m2. The contents of the hydrophobic additive in Examples 1-4 are
summarized in Table 1.
TABLE-US-00001 TABLE 1 Example X [wt %] 1 0 2 3 3 6 4 10
[0285] Examples 1-4 were tested for Low Surface Tension Strike
Through (LST-ST)--measured in seconds. The results are summarized
in Table 2. Each sample was tested 15 times, the average is
provided below in Table 2.
TABLE-US-00002 TABLE 2 Example 1 2 3 4 Average 4.86 8.15 11.20
13.59 Std. Dev 0.68 1.81 1.53 3.81 Min 3.80 6.97 8.25 8.80 Max 6.25
14.13 14.13 20.75
Example 5-7
[0286] Three S single layer nonwovens were produced from 100%
Ziegler-Natta polypropylene and were thermally bonded. Each of the
single S-layers had a weight of 20 g/m2. After the web making
process of the nonwovens they were thermally treated with an
in-line Omega Drying oven at 90.degree. C., 120.degree. C. and
135.degree. C., for Example 5, 6 and 7, respectively.
Example 8
[0287] An S single layer nonwoven was produced from 100%
Ziegler-Natta polypropylene and was thermally bonded. The single
S-layer had a weight of 20 g/m2. After the web making process the
nonwoven was thermally treated with an in-line IR-heater set to 65%
power at the center and 60% at the edge of the nonwoven web.
Example 9
[0288] An S single layer nonwoven was produced from 100%
Ziegler-Natta polypropylene and was thermally bonded. The single
S-layer had a weight of 20 g/m2. After the web making process the
nonwoven was thermally treated with an in-line Omega Drying oven at
120.degree. C. Opposite Example 6, the through put had been
decreased in the production of the material, resulting in a
decreased line speed to increase the duration of the heat
treatment. The resulting heat treatment of Example 9 was 15% longer
than that of Example 6.
TABLE-US-00003 TABLE 3 Example 5 6 7 8 9 Average 6.27 7.14 7.03
6.89 7.81 Std. Dev 1.21 0.74 0.98 0.81 1.26 Min 3.27 5.95 6.01 5.73
5.97 Max 7.57 8.25 9.00 8.21 10.42
Examples 10-13
[0289] Four S single layer nonwovens were produced from 90 wt %
Ziegler-Natta polypropylene and 10 wt % of a hydrophobic melt
additive (PPM17000 High Load Hydrophobic) and were thermally
bonded. Each of the single S-layers had a weight of 20 g/m2. After
the web making process of the nonwovens they were thermally treated
with an in-line Omega Drying oven set to 90.degree. C., 105.degree.
C., 120.degree. C. and 135.degree. C. for Example 10, 11, 12 and
13, respectively.
Examples 14-17
[0290] Four S single layer nonwovens were produced from 90 wt %
Ziegler-Natta polypropylene and 10 wt % hydrophobic melt additive
(PPM17000 High Load Hydrophobic) and were thermally bonded. Each of
the single S-layers had a weight of 20 g/m2. After the web making
process of the nonwovens they were thermally treated with an
in-line IR-heater set to 50% power at the center and 45% at the
edge of the nonwoven web, 60% power at the center and 55% at the
edge of the nonwoven web, 65% power at the center and 50% at the
edge of the nonwoven web, and 70% power at the center and 65% at
the edge of the nonwoven web for Example 14, 15, 16 and 17,
respectively.
Example 18
[0291] An S single layer nonwoven was produced from 90 wt %
Ziegler-Natta polypropylene and 10 wt % hydrophobic melt additive
(PPM17000 High Load Hydrophobic) and was thermally bonded. The
single S-layer had a weight of 20 g/m2. After the web making
process of the nonwoven it was thermally treated with an in-line
IR-heater set to 65% power at the center and 60% at the edge of the
nonwoven web, followed by heating in an Omega Drying oven at
120.degree. C.
[0292] The hydrophobic additive content and heat treatment for
Examples 10-18 are summarized in Table 4 below.
TABLE-US-00004 TABLE 4 Configuration S 20 g/m2 IR heater, Omega
Drying PPM17000 in S center/edge oven temperature Example [%] [%]
[.degree. C.] 10 10 N/A 90 11 10 N/A 105 12 10 N/A 120 13 10 N/A
135 14 10 50/45 N/A 15 10 60/55 N/A 16 10 65/60 N/A 17 10 70/65 N/A
18 10 65/60 120
[0293] LST-ST was measured on Example 10-18. The results are shown
in Table 5.
TABLE-US-00005 TABLE 5 Example 10 11 12 13 14 15 16 17 18 Average
58.87 98.99 186.30 461.72 19.25 19.90 221.99 84.40 230.33 Std. Dev
16.65 52.77 88.53 128.77 5.81 6.15 93.35 26.36 109.69 Min 35.59
37.91 51.80 198.51 11.38 12.71 95.32 33.97 110.34 Max 79.87 213.77
305.67 657.52 36.15 30.45 408.33 126.05 410.14
Example 19
[0294] An S single layer nonwoven was produced from 90 wt %
Ziegler-Natta polypropylene and 10 wt % hydrophobic melt additive
(PPM17000 High Load Hydrophobic) and was thermally bonded. The
single S-layer had a weight of 20 g/m2. Compared to Example 4, the
temperature of the calender thermally bonding the nonwoven was
increased with +10.degree. C.
[0295] Table 6 below shows the LST-ST results from Example 19.
TABLE-US-00006 TABLE 6 Example 19 Average 27.25 Std. dev. 13.75 Min
14.50 Max 60.64
[0296] It can be see that when increasing the calender temperature
with 10.degree. C., the LST ST increases from 13.59 seconds (4) to
27.25 seconds (19).
Example 20
[0297] An S single layer nonwoven was produced from 90%
Ziegler-Natta polypropylene and 10 wt % of a hydrophobic melt
additive (PPM17000 High Load Hydrophobic) and was thermally bonded.
The single S-layer had a weight of 20 g/m2. After the web making
process the nonwoven was thermally treated with an in-line Omega
Drying oven at 120.degree. C. As Example 13, the through put had
been decreased in the production of the material, resulting in a
decreased line speed to increase the duration of the in-line heat
treatment. The resulting heat treatment of Example 20 was 15%
longer than that of Example 12 and comparable to the heat treatment
of Example 6.
[0298] Table 7 below shows the LST-ST results from Example 20.
TABLE-US-00007 TABLE 7 Example 20 Average 354.86 Std. dev. 194.08
Min 134.31 Max 656.06
[0299] It can be seen that when increasing the heat treatment time
with 15%, it increases the performance in terms of LST ST from
186.30 seconds (Example 12) to 354.86 seconds (Example 20).
Example 21
[0300] A Spunbond single layer fabric was produced with
bi-component core/sheath configuration, consisting of 70 wt % core
and 30 wt % sheath. The core comprised 100% Ziegler-Natta
polypropylene. The sheath comprised 67 wt % Ziegler-Natta
polypropylene and 33 wt % hydrophobic melt additive (PPM17000 High
Load Hydrophobic). The nonwoven was thermally bonded. The single
S-layer had a weight of 20 g/m2.
Example 22-24
[0301] Spunbond single layer fabrics were produced with
bi-component core/sheath configuration, consisting of 70 wt % core
and 30 wt %. The core comprised 100 wt % Ziegler-Natta
polypropylene. The sheath comprised 100-X wt % Ziegler-Natta
polypropylene and X wt % hydrophobic melt additive (PPM17000 High
Load Hydrophobic). The nonwoven was thermally bonded. Each of the
single S-layer had a weight of 20 g/m2. After the web making
process of the nonwovens they were thermally treated by an in-line
IR-heater set to 65% power at the center and 50% at the edge of the
nonwoven web.
[0302] The contents of the hydrophobic additive in the sheath of
the fiber in Examples 22-24 are summarized in below Table 8.
TABLE-US-00008 TABLE 8 Example X [wt %] 22 10 23 20 24 33
[0303] Table 9 below shows LST-ST results on Examples 21-24.
TABLE-US-00009 TABLE 9 Example 21 22 23 24 Average 28.47 14.12
78.11 276.74 Std. Dev 11.73 2.50 21.32 112.54 Min 10.03 10.70 43.19
146.09 Max 50.50 20.02 117.86 502.41
Example 25
[0304] A spunbond single layer fabric was produced with
bi-component core/sheath configuration, consisting of 70 wt % core
and 30 wt %. The core comprised 100 wt % Ziegler-Natta
polypropylene. The sheath comprised 67 wt % propylene-based
elastomer (consisting of approx. 15 wt % ethylene) and 33 wt % of a
hydrophobic melt additive (PPM17000 High Load Hydrophobic). The
nonwoven was thermally bonded. The single S-layer had a weight of
20 g/m2.
[0305] Table 10 below shows the LST-ST results on Example 25:
TABLE-US-00010 TABLE 10 Example 25 Average 100.34 Std. Dev 36.86
Min 38.32 Max 138.89
[0306] Example 21 to Example 25 reveals an increase in LST-ST from
28.47 seconds to 100.34 seconds when substituting Ziegler-Natta
polypropylene in the sheath of the bi-component fiber with a
propylene-based elastomer in the sheath of the bi-component
fiber.
Example 26
[0307] A spunbond single layer fabric was produced was produced
from 80 wt % Ziegler-Natta polypropylene, 10 wt % of a hydrophobic
melt additive (PPM17000 High Load Hydrophobic), and 10 wt % of a
Calcium Carbonate masterbatch (Fiberlink 201S). The fabric was
thermally bonded. The single S-layer had a weight of 20 g/m2. After
the web making process of the nonwoven it was thermally treated by
an in-line IR-heater set to 65% power at the center and 60% at the
edge of the nonwoven web followed by in-line heating in an Omega
Drying oven at 120.degree. C.
Example 27
[0308] A spunbond single layer fabric was produced was produced
from 90 wt % Ziegler-Natta polypropylene, and 10 wt % of Calcium
Carbonate masterbatch (Fiberlink 201S) and was thermally bonded.
The single S-layer had a weight of 20 g/m2. After the web making
process of the nonwoven it was thermally treated in an in-line
Omega Drying oven at 120.degree. C.
[0309] An overview of Example 26 and 27 is provided in Table 11
below.
TABLE-US-00011 TABLE 11 Configuration S 20 g/m2 PPM17000 Fiberlink
Omega Drying IR heater, in S 201S oven temperature center/edge
Example [%] [%] [.degree. C.] [%] 26 10 10 120 65/60 27 0 10 120
N/A
[0310] LST-ST results on Examples 26 and 27 are illustrated in
Table 12 below.
TABLE-US-00012 TABLE 12 Example 26 27 Average 679.98 5.51 Std. dev.
158.50 0.61 Min 522.90 4.55 Max 898.10 6.84
[0311] The LST-ST results reveal a LST ST of 5.51 seconds for
Example 27, which shows that the presence of CaCO3 alone does not
increase the LST-ST performance. The LST-ST of Example 26 compared
to Example 18, reveals that the presence of CaCO3 and the applied
heat treatments of the IR-heater and Omega Drying oven increases
the LST ST from 230.33 seconds to 679.98 seconds. When comparing
the state of the art of Example 4 to Example 26, the performance
increases from 13, 59 seconds to 679.98 seconds.
Examples 28-29
[0312] Two SMMS-multilayered nonwoven fabrics were produced from
Ziegler-Natta polypropylene. A hydrophobic additive (PPM17000 High
Load Hydrophobic) was added to the various layers as described in
Table 13. After the web making process of Example 29 the fabric was
heat treated with an in-line Omega Drying oven.
[0313] Table 13 gives an overview on material layup, additive
content and heat treatment.
TABLE-US-00013 TABLE 13 Lay-up [g] Configuration S M M S SMMS 5.5 1
1 5.5 13 Total Omega Drying PPM17000 oven temperature Example
PPM17000 per beam [%] [%] [.degree. C.] 28 0 6 6 6 3.5 N/A 29 0 6 6
6 3.5 120
[0314] Examples 28-29 were tested for Low Surface Tension Strike
Through (LST-ST). The results are summarized in Table 14.
TABLE-US-00014 TABLE 14 Example 28 29 Average 24.52 31.30 Std. dev.
5.03 4.70 Min 16.52 40.60 Max 36.19 59.50
Examples 30-32
[0315] Three SS materials were produced with the spunbond fibers in
both layers being bi-component fibers of core/sheath configuration
with a polyethylene sheath, accounting for 30 wt % of the total
fiber, and polypropylene core, accounting for 70 wt % of the total
fiber. A hydrophobic additive (PM16310) was added in 17% to the
bi-component's PE sheath of both of S layers for Examples 30-32.
After the web making process of Example 31-32, the nonwovens were
heat treated with an in-line Omega Drying oven of 100.degree. C.
and 120.degree. C. for Example 31 and Example 32, respectively.
[0316] Table 15 gives an overview on material layup, additive
content and heat treatment.
TABLE-US-00015 TABLE 15 Lay-up [g] S Sheath (PE) Configuration SS
3.75 S 25 Core (PP) PPM17000 in Core (PP) Sheath (PE) Omega Drying
8.75 sheath per beam 8.75 3.75 oven temperature Example [%] Total
PPM17000 [%] [.degree. C.] 30 17 17 5.1 N/A 31 17 17 5.1 100 32 17
17 5.1 120
[0317] Examples 30-32 were tested for Low Surface Tension Strike
Through (LST-ST). The results are summarized in Table 16.
TABLE-US-00016 TABLE 16 Example 30 31 32 Average 25.52 22.49 31.64
Min 12.02 12.88 16.97 Max 47.98 44.03 54.21 Std. dev. 10.31 7.00
9.10
[0318] Some of the above samples were tested via FTIR along with
some additional examples. The results are shown in Tables
17-19.
TABLE-US-00017 TABLE 17 ATR_Germanium_Measurement 1
ATR_Germanium_Measurement 2 Heating (d_p = 0, 41 .mu.m) (d_p = 0,
41 .mu.m) ATR_Germanium_Mean Mono/ information wt % wt % wt %
Example bico and misc. Masterbatch Masterbatch Masterbatch 13 Mono
135.degree. C. Oven 69.6 70.6 70.1 12 Mono 120.degree. C. Oven 85.9
68.2 77.05 20 Mono 120.degree. C. Oven 71.5 74.5 73 11 Mono
105.degree. C. Oven 67.5 67.1 67.3 10 Mono 90.degree. C. Oven 68.5
70.2 69.35 18 Mono 120.degree. C. Oven + IR 75.8 72.3 74.05 14 Mono
50% IR 71.4 72.9 72.15 16 Mono 70% IR (high 91.5 90 90.75 strike
through) 2 Mono Reference 21.6 25.2 23.4 3 wt % GTS 3 Mono
Reference 42.1 42.8 42.45 6 wt % GTS 4 Mono Reference 57.5 62.6
60.05 10 wt % GTS 15 Mono 60% IR 55.5 56.4 55.95 17 Mono 70% IR
(low 65.3 70.4 67.85 strike through) 33 Bico Bico 3 wt % 30.6 23.7
27.15 GTS + IR 34 Bico Bico 6 wt % 58.8 49.3 54.05 GTS + IR 35 Bico
Bico 10 wt % 74.2 84.2 79.2 GTS + IR 36 Bico Bico 10 wt % 73.3 74.3
73.8 GTS no IR
TABLE-US-00018 TABLE 18 Heating ATR_Diamond_Measurement 1
ATR_Diamond_Measurement 2 ATR_Diamond_Mean Mono/ information (d_p =
1.51 .mu.m) (d_p = 1.51 .mu.m) wt % Example bico and misc. wt %
Masterbatch wt % Masterbatch Masterbatch 13 Mono 135.degree. C.
Oven 46.9 43.4 45.15 12 Mono 120.degree. C. Oven 44.9 39.3 42.1 20
Mono 120.degree. C. Oven 44.7 45.4 45.05 11 Mono 105.degree. C.
Oven 39.3 38.9 39.1 10 Mono 90.degree. C. Oven 39.4 37.3 38.35 18
Mono 120.degree. C. Oven + IR 44.1 44.1 44.1 14 Mono 50% IR 41 41.2
41.1 16 Mono 70% IR (high 46.1 50.6 48.35 strike through) 2 Mono
Reference 12.2 10.6 11.4 3 wt % GTS 3 Mono Reference 22.8 23.7
23.25 6 wt % GTS 4 Mono Reference 33.2 32.9 33.05 10 wt % GTS 15
Mono 60% IR 34.1 35.7 34.9 17 Mono 70% IR (low 41.6 39.5 40.55
strike through) 33 Bico Bico 3 wt % 14.8 13 13.9 GTS + IR 34 Bico
Bico 6 wt % 29.8 27.1 28.45 GTS + IR 35 Bico Bico 10 wt % 43.2 48.2
45.7 GTS + IR 36 Bico Bico 10 wt % 39.8 45.4 42.6 GTS no IR
TABLE-US-00019 TABLE 19 Transmission_Measurement 1
Transmission_Measurement 2 Transmission_Mean Mono/ Heating
information wt % wt % wt % Example bico and misc. Masterbatch
Masterbatch Masterbatch 13 Mono 135.degree. C. Oven 9.7 9.4 9.55 12
Mono 120.degree. C. Oven 8.7 8.7 8.7 20 Mono 120.degree. C. Oven
8.5 7.9 8.2 11 Mono 105.degree. C. Oven 9.4 9.9 9.65 10 Mono
90.degree. C. Oven 9.9 10.8 10.35 18 Mono 120.degree. C. Oven + IR
9.1 8.1 8.6 14 Mono 50% IR 8.7 10 9.35 16 Mono 70% IR (high strike
through) 8.5 8.8 8.65 2 Mono Reference 3 wt % GTS 3.6 3.7 3.65 3
Mono Reference 6 wt % GTS 6.3 5.7 6 4 Mono Reference 10 wt % GTS
9.1 8.5 8.8 15 Mono 60% IR 10 8.9 9.45 17 Mono 70% IR (low strike
through) 8.6 8.6 8.6 33 Bico Bico 3 wt % GTS + IR 3.3 3.2 3.25 34
Bico Bico 6 wt % GTS + IR 5.3 5.9 5.6 35 Bico Bico 10 wt % GTS + IR
8.5 9.2 8.85 36 Bico Bico 10 wt % GTS no IR 8.3 8.3 8.3
[0319] For the bi-component nonwovens, no melt additive was
provided in the core. The melt additive levels and fiber
compositions are provided below with regard to Table 20.
TABLE-US-00020 TABLE 20 Mono/ Heating information GTS addition in
Addition, hydrophobic Example bico and misc. total fiber % melt
additive % 13 Mono 135.degree. C. Oven 10 10 12 Mono 120.degree. C.
Oven 10 10 20 Mono 120.degree. C. Oven 10 10 11 Mono 105.degree. C.
Oven 10 10 10 Mono 90.degree. C. Oven 10 10 18 Mono 120.degree. C.
Oven + IR 10 10 14 Mono 50% IR 10 10 16 Mono 70% IR (high strike
through) 10 10 2 Mono Reference 3 wt % GTS 3 3 3 Mono Reference 6
wt % GTS 6 6 4 Mono Reference 10 wt % GTS 10 10 15 Mono 60% IR 10
10 17 Mono 70% IR (low strike through) 10 10 33 Bico Bico 3 wt %
GTS + IR 3 10 34 Bico Bico 6 wt % GTS + IR 6 20 35 Bico Bico 10 wt
% GTS + IR 10 33 36 Bico Bico 10 wt % GTS no IR 10 33
[0320] Table 21 provides information regarding the style and
temperature of the heating applied to the nonwoven examples.
TABLE-US-00021 TABLE 21 Heating IR IR heater IR heater Drum Dryer
Mono/ information heater power at power at dryer temperature
Example bico and misc. Y/N center % edge % Y/N .degree. C. 13 Mono
135.degree. C. Oven N -- -- Y 135 12 Mono 120.degree. C. Oven N --
-- Y 120 20 Mono 120.degree. C. Oven N -- -- Y 120 11 Mono
105.degree. C. Oven N -- -- Y 105 10 Mono 90.degree. C. Oven N --
-- Y 90 18 Mono 120.degree. C. Oven + IR Y 65 60 Y 120 14 Mono 50%
IR Y 50 45 N -- 16 Mono 70% IR (high Y 70 65 N -- strike through) 2
Mono Reference N -- -- N -- 3 wt % GTS 3 Mono Reference N -- -- N
-- 6 wt % GTS 4 Mono Reference N -- -- N -- 10 wt % GTS 15 Mono 60%
IR Y 60 55 N -- 17 Mono 70% IR (low Y 70 65 N -- strike through) 33
Bico Bico 3 wt % Y 65 60 N -- GTS + IR 34 Bico Bico 6 wt % Y 65 60
N -- GTS + IR 35 Bico Bico 10 wt % Y 65 60 N -- GTS + IR 36 Bico
Bico 10 wt % N -- -- N -- GTS no IR
[0321] Table 22 provides information regarding permeability and
basis weight and whether fibrillation was observed.
TABLE-US-00022 TABLE 22 Mono/ Information/what has LST ST Air
permeability Basis weight Example bico changed to reference s
L/(m.sup.2*s) gsm 13 Mono 135.degree. C. Oven 462 12 Mono
120.degree. C. Oven 186 20 Mono 120.degree. C. Oven 355 11 Mono
105.degree. C. Oven 99 10 Mono 90.degree. C. Oven 59 18 Mono
120.degree. C. Oven + IR 230 14 Mono 50% IR 19 3083 19.8 16 Mono
70% IR (high strike through) 222 2291 22.5 2 Mono Reference 3 wt %
GTS 8 4212 19.5 3 Mono Reference 6 wt % GTS 11 4118 19.6 4 Mono
Reference 10 wt % GTS 14 3938 19.8 15 Mono 60% IR 20 3604 21.5 17
Mono 70% IR (low strike through) 84 2676 25.5 33 Bico Bico 3 wt %
GTS + IR 14 3486 21.9 34 Bico Bico 6 wt % GTS + IR 78 2684 22.9 35
Bico Bico 10 wt % GTS + IR 277 2408 24.9 36 Bico Bico 10 wt % GTS
no IR 28 3866 20.4
[0322] Examples 37-40 are polyethylene films comprising 0.6 percent
by weight of melt additive. Sample 37 comprised 0 percent by weight
of high density polyethylene and was exposed to a temperature of 25
degrees C. Sample 38 comprised 0 percent by weight of high density
polyethylene and was exposed to a temperature of 35 degrees C. for
6 hours. Sample 39 comprised 40 percent by weight of high density
polyethylene and was exposed to a temperature of 25 degrees C.
Sample 40 comprised 40 percent by weight of high density
polyethylene and was exposed to a temperature of 35 degrees C. for
6 hours.
TABLE-US-00023 TABLE 23 Total Melt- TD NMR surface additive Conc
Temperature surfactant Example [wt %] (.degree. C.) [wt %] STDEV 37
0.6 25 0.15 0.02 38 0.6 35 0.22 0.02 39 0.6 25 0.06 0.00 40 0.6 35
0.08 0.00
Precursor Material
[0323] Similarly, the material webs of the present invention begin
with the thermoplastic polymeric material. As noted previously, the
material webs of the present invention may comprise any suitable
material for example, nonwoven webs, film webs, or laminates
created therefrom. Where the material webs of the present invention
comprise laminates, the laminates may comprise a plurality of
nonwoven layers, a plurality of film layers, or at least one
nonwoven layer and at least one film layer. Additional forms are
contemplated where the material webs of the present invention
comprise a nonwoven web comprising multiple nonwoven strata.
Regardless of the form of the material web, any suitable material
may be utilized.
[0324] For those forms where the material webs comprise a nonwoven,
any suitable thermoplastic polymer may be utilized. Some suitable
thermoplastic polymers are polymers that melt and then, upon
cooling, crystallize or harden, but can be re-melted upon further
heating. Suitable thermoplastic polymers used herein have a melting
temperature (also referred to as solidification temperature) from
about 60.degree. C. to about 300.degree. C., from about 80.degree.
C. to about 250.degree. C., or from 100.degree. C. to 215.degree.
C. And, the molecular weight of the thermoplastic polymer should be
sufficiently high to enable entanglement between polymer molecules
and yet low enough to be melt spinnable.
[0325] The thermoplastic polymers can be derived any suitable
material including renewable resources (including bio-based and
recycled materials), fossil minerals and oils, and/or
biodegradeable materials. Some suitable examples of thermoplastic
polymers include polyolefins, polyesters, polyamides, copolymers
thereof, and combinations thereof. Some exemplary polyolefins
include polyethylene or copolymers thereof, including low density,
high density, linear low density, or ultra low density
polyethylenes such that the polyethylene density ranges between
0.90 grams per cubic centimeter to 0.97 grams per cubic centimeter,
between 0.92 and 0.95 grams per cubic centimeter or any values
within these ranges or any ranges within these values. The density
of the polyethylene may be determined by the amount and type of
branching and depends on the polymerization technology and
co-monomer type.
[0326] Some suitable examples of polypropylene and/or polypropylene
copolymers, include atactic polypropylene; isotactic polypropylene,
syndiotactic polypropylene, and combination thereof, "hereafter
propylene polymers" can also be used. Polypropylene copolymers,
especially ethylene can be used to lower the melting temperature
and improve properties. These polypropylene polymers can be
produced using metallocene and Ziegler-Natta catalyst systems.
These polypropylene and polyethylene compositions can be combined
together to optimize end-use properties. Polybutylene is also a
useful polyolefin and may be used in some embodiments. Other
suitable polymers include polyamides or copolymers thereof, such as
Nylon 6, Nylon 11, Nylon 12, Nylon 46, Nylon 66; polyesters or
copolymers thereof, such as maleic anhydride polypropylene
copolymer, polyethylene terephthalate; olefin carboxylic acid
copolymers such as ethylene/acrylic acid copolymer, ethylene/maleic
acid copolymer, ethylene/methacrylic acid copolymer, ethylene/vinyl
acetate copolymers or combinations thereof; poly-lactic acid;
polyacrylates, polymethacrylates, and their copolymers such as
poly(methyl methacrylates).
[0327] Non-limiting examples of suitable commercially available
polypropylene or polypropylene copolymers include Basell Profax
PH-835 (a 35 melt flow rate Ziegler-Natta isotactic polypropylene
from Lyondell-Basell), Basell Metocene MF-650W (a 500 melt flow
rate metallocene isotactic polypropylene from Lyondell-Basell),
Moplen, HP2833, HP462R and S, HP551R, HP552N, HP552R, HP553R,
HP561R, HP563S, HP567P, HP568S, RP3231, Polybond 3200 (a 250 melt
flow rate maleic anhydride polypropylene copolymer from Crompton),
Exxon Achieve 3854 (a 25 melt flow rate metallocene isotactic
polypropylene from Exxon-Mobil Chemical), Mosten NB425 (a 25 melt
flow rate Ziegler-Natta isotactic polypropylene from Unipetrol),
Danimer 27510 (a polyhydroxyalkanoate polypropylene from Danimer
Scientific LLC), Achieve 3155 (a 35 melt flow rate Ziegler-Natta
isotactic polypropylene from Exxon Mobil),
[0328] The thermoplastic polymer component can be a single polymer
species as described above or a blend of two or more thermoplastic
polymers as described above, e.g. two different polypropylene
resins. As an example, the constituent fibers of the first nonwoven
layer can be comprised of polymers such as polypropylene and blends
of polypropylene and polyethylene. The second nonwoven layer may
comprise fibers selected from polypropylene,
polypropylene/polyethylene blends, and polyethylene/polyethylene
teraphthalate blends. In some embodiments, the second nonwoven
layer may comprise fibers selected from cellulose rayon, cotton,
other hydrophilic fiber materials, or combinations thereof. The
fibers can also comprise a super absorbent material such as
polyacrylate or any combination of suitable materials.
[0329] The fibers of the first nonwoven layer and/or the second
nonwoven layer can be monocomponent, bi-component, and/or
bi-constituent, round or non-round (e.g., capillary channel
fibers), and can have major cross-sectional dimensions (e.g.,
diameter for round fibers) ranging from 0.1-500 microns. The
constituent fibers of the nonwoven precursor web may also be a
mixture of different fiber types, differing in such features as
chemistry (e.g. polyethylene and polypropylene), components (mono-
and bi-), denier (micro denier and >2 denier), shape (i.e.
capillary and round) and the like. The constituent fibers can range
from about 0.1 denier to about 100 denier.
[0330] As used herein, the term "monocomponent" fiber refers to a
fiber formed from one extruder using one or more polymers. This is
not meant to exclude fibers formed from one polymer to which small
amounts of additives have been added for coloration, antistatic
properties, lubrication, hydrophilicity, etc.
[0331] As used herein, the term "bi-component fibers" refers to
fibers which have been formed from at least two different polymers
extruded from separate extruders but spun together to form one
fiber. Bi-component fibers are also sometimes referred to as
conjugate fibers or multicomponent fibers. The polymers are
arranged in substantially constantly positioned distinct zones
across the cross-section of the bi-component fibers and extend
continuously along the length of the bi-component fibers. The
configuration of such a bi-component fiber may be, for example, a
sheath/core arrangement wherein one polymer is surrounded by
another, or may be a side-by-side arrangement, a pie arrangement,
or an "islands-in-the-sea" arrangement. Some specific examples of
fibers which can be used in the first nonwoven layer include
polyethylene/polypropylene side-by-side bi-component fibers.
Another example, is a polypropylene/polyethylene bi-component fiber
where the polyethylene is configured as a sheath and the
polypropylene is configured as a core within the sheath. Still
another example, is a polypropylene/polypropylene bi-component
fiber where two different propylene polymers are configured in a
side-by-side configuration.
[0332] Bi-component fibers may comprise two different resins, e.g.
a first polypropylene resin and a second polypropylene resin. The
resins may have different melt flow rates, molecular weights, or
molecular weight distributions. Ratios of the 2 different polymers
may be about 50/50, 60/40, 70/30 or any ratio within these ratios.
The ratio may be selected to control the amount of crimp, strength
of the nonwoven layer, softness, bonding or the like.
[0333] As used herein, the term "bi-constituent fibers" refers to
fibers which have been formed from at least two polymers extruded
from the same extruder as a blend. Bi-constituent fibers do not
have the various polymer components arranged in relatively
constantly positioned distinct zones across the cross-sectional
area of the fiber and the various polymers are usually not
continuous along the entire length of the fiber, instead usually
forming fibrils which start and end at random. Bi-constituent
fibers are sometimes also referred to as multi-constituent fibers.
In other examples, a bi-component fiber may comprise a
multi-constituent components.
[0334] As used herein, the term "non-round fibers" describes fibers
having a non-round cross-section, and includes "shaped fibers" and
"capillary channel fibers." Such fibers can be solid or hollow, and
they can be tri-lobal, delta-shaped, and can be fibers having
capillary channels on their outer surfaces. The capillary channels
can be of various cross-sectional shapes such as "U-shaped",
"H-shaped", "C-shaped" and "V-shaped". One practical capillary
channel fiber is T-401, designated as 4DG fiber available from
Fiber Innovation Technologies, Johnson City, Tenn. T-401 fiber is a
polyethylene terephthalate (PET polyester).
[0335] The fibers of the first nonwoven layer and/or the second
nonwoven layer may comprise additives in addition to their
constituent material. For example, suitable additives include
additives for coloration, antistatic properties, lubrication,
softness, hydrophilicity, hydrophobicity and the like and
combinations thereof.
[0336] Further regarding coloration, the first layer and/or the
second layer may comprise pigments, inks or dyes to achieve any
color difference as provided herein. The fibers of the first layer
and the fibers of the second layer may differ from each other in
pigmentation. As used herein, to "differ in pigmentation" or
"difference in pigmentation" means (a) the fibers of the first
layer comprise a pigment which is different from the pigment of the
second layer; or (b) the fibers of the first layer comprise a
different combination of pigments; or (c) the fibers of the first
layer comprise different amounts of the same pigment(s) versus the
second layer; or (d) combinations of any of options a) to c). The
pigment or colorant may be added uniformly throughout the fibers
within each layer or may be added to one or both components in same
or different type/amount within multicomponent fibers.
[0337] A pigment is a material, which can be organic or inorganic
and may include activatable, structural and or special effects
pigments. A pigment changes the color of reflected or transmitted
light as the result of wavelength-selective absorption. This
physical process differs from fluorescence, phosphorescence, and
other forms of luminescence, in which a material emits light. A
pigment is a generally insoluble powder, which differs from a dye,
which either is itself a liquid or is soluble in a solvent
(resulting in a solution). Dyes are often used to provide a print
on the surface of a nonwoven web, such as graphics, pattern or
images. Hence, these dyes do not form a part of the fibers of the
nonwoven web but are rather applied on the web surface. In the
present invention the pigments may be comprised within the fibers
of the multilayered nonwoven web, which eliminates the risk of
rub-off or wash-off of the color(s) imparted to the multilayered
nonwoven web by the pigment.
[0338] For the present invention, the pigment will typically be
mixed with the thermoplastic material, of which the fibers are
made. Often, the pigment is added to the thermoplastic material in
the form of a master batch or concentrate at the time of formation
of the fibers. Colored master batches useful for the present
invention include polypropylene based custom color master batches
e.g. supplied by Ampacet; Lufilen and Luprofil supplied by BASF;
Remafin for polyolefin fibers, Renol-AT for polyester fibers,
Renol-AN for polyamide fibers and CESA for renewable polymers
supplied by Clamant. Hence, the pigment will be suspended in the
molten thermoplastic material prior to the thermoplastic material
being forced through the spinnerets to form and lay down the fibers
which form the nonwoven web.
[0339] To increase the whiteness and/or opacity of the fibers in
either or both layers, titanium dioxide (TiO2) may be used.
Different crystal forms are available, however most preferred are
rutile or anatase TiO2. Other white pigments include zinc oxide,
zinc sulfide, lead carbonate or calcium carbonate. To create a
black color, carbon black or any other suitable colorant may be
used. Various colored inorganic pigments may be used depending upon
the desired color and may include metal oxides, hydroxides and
sulfides or any other suitable material. Non-limiting examples of
inorganic pigments include cadmium orange, iron oxide, ultramarine,
chrome oxide green. One or more pigments may be combined to create
the desired color. Non-limiting examples of organic colorants
include anthraquinone pigments, azo pigments, benzimidazolone
pigments, BONA Lakes, Dioxazine, Naphthol, Perylene, Perinone,
Phthalocyanine, Pyranthrone, Quinacridones. Effects pigments
including metal, pearlescent and fluorescent may also be used.
Various colorants are described in Plastics Additives Handbook, 5th
Edition.
[0340] The nonwoven materials suitable for use in the material webs
of the present invention may be made from any suitable process. For
example, as noted previously, the material web may comprise
nonwoven layers or nonwoven strata produced via a spunbond process,
or carded webs comprising staple fibers. Additional processes are
contemplated, for example meltblown process. In some forms, the
material web may comprise nonwovens which comprise spunbond
filaments ("S"); meltblown fibers ("M"), finer fibers (fibers with
average diameters less than one micron or 1000 nanometers (an
"N-fiber")). In some forms, the material webs of the present
invention may comprise a combination of fibers/filaments. For
example, SMS, SM, SMMS, SMSS, SNS, SN, SNM, or SMN.
[0341] Forms are contemplated where melt additive is provided in
one or more of the fiber/filament types. For example, an SMS may
comprise melt additive in the M filaments and no melt additive in
one or both S filaments. Additional examples are provided
herein.
[0342] Other suitable processes for the material webs of the
present invention comprise dry-laid and wet-laid. Dry-laid
technologies include carding and air-laying. These technologies may
be combined with each other, e.g., dry-laid with melt-spun, to form
multi-layer, functional nonwoven substrates.
[0343] The air-laid process also uses fibers of discrete length,
though these fibers are often shorter than the staple fibers used
for carding. The length of fibers used in air-laying typically
ranges from 2 mm to 20 mm, though lengths beyond this range may
also be used. Particles may also be deposited into the fibrous
structure during the air-laying process. Some fibers for air-laying
may be prepared similarly as for carding, i.e., opening and
blending as described above. Other fibers, such as pulp, may use
mills, such as hammer mills or disc mills, to individualize the
fibers. The various fibers may be blended to improve the uniformity
of properties of the finished nonwoven substrate. The air-laying
forming device combines external air and the fibers and/or
particles so that the fibers and/or particles are entrained in the
airsteam. After entrainment, the fibers and/or particles are
collected as a loose web upon a moving foraminous surface, such as
a wire mesh conveyor belt, for example. The air-laying process may
contain a single air-laying forming device or multiple air-laying
forming devices in line with one another, where the fibers and/or
particles of the subsequent air-laying forming device are deposited
on top of the fibers and/or particles from a preceding air-laying
forming device, thereby allowing manufacture of a multi-layered
nonwoven substrate.
[0344] Wet-laid nonwovens are made with a modified papermaking
process and typically use fibers in the range of 2 mm to 20 mm,
though lengths beyond this range have also been used. Some fibers
for wet-laying may be prepared similarly as for carding, i.e.,
opening and blending as described above. Other fibers, such as
pulp, may use mills, such as hammer mills or disc mills, to
individualize the fibers. The fibers are suspended in water,
possibly with other additives like bonding agents, and this slurry
is typically added to a headbox from where it flows onto a wet-laid
forming device to create a sheet of material. After initial water
removal, the web is bonded and dried.
[0345] Spunlace nonwovens are typically carded and hydroentangled.
The fibers of the spunlace nonwoven are first carded. In order to
provide the carded fibers with integrity in the Z-direction and in
CD, the carded fibers are then subjected to hydroentangling.
Instead of carded nonwovens, spunlace nonwovens may be air-laid or
wet-laid and subsequently hydroentangled.
[0346] The constituent layers/strata of the material web may be
provided with structural integrity via a variety of different
processes. Some examples include thermal point bonding, air through
bonding, hydroentangling, and needlepunching each of which is well
known in the art. Similarly, the attachment of the material web
layers/strata may be achieved by a variety of different processes.
Examples of such processes are discussed hereafter. The constituent
materials of the material webs of the present invention can be
joined together by any suitable process. An example of a suitable
process include calendar bonding. It is worth noting that for those
material webs of the present invention for which filled tufts are
desired, the percentage of bond area between constituent filaments
of the material web should be carefully considered. The inventors
have found that with crimped filaments, too low of a calendar bond
area does not allow for good formation of filled tufts. And too low
of a calendar bond area yields a material web with low strength and
poor abrasion resistance. However, too high of a calendar bond area
reduces the length of filaments between adjacent bonds which
inhibits the amount of uncoiling and/or displacement possible.
Specifically, too high of a calendar bond area inhibits the
movement of the filaments such that when subjected to the localized
Z-direction urging, described herein for the formation of filled
tufts and outer tufts, the crimped filaments have very limited
ability to uncoil. In such configurations, the crimped filaments
must undergo plastic deformation or break once the amount of
uncoiling surpasses the amount of applied process strain. The
inventors have found that calendar bond area above about 10 percent
and less than about 18 percent allows for a good balance of
filament mobility and free filament length available for uncoiling
but still provides sufficient strength in the nonwoven web for
manipulations of the crimped filaments as well as abrasion and
tearing resistance in use.
[0347] In some forms of the present invention, the nonwoven webs
comprising crimped filaments may comprise a calendar bond area of
between about 10 percent to about 18 percent or between about 12
percent and 16 percent, specifically including all values within
these ranges or any range created thereby. Nonwoven webs of the
present invention which do not include crimped filaments may
comprise a calendar bond area of between about 5 percent to about
30 percent, between about 10 percent to about 20 percent,
specifically including all values within these ranges and any
ranges created thereby. The bonds can be shaped like dots,
diamonds, ovals or any other suitable shape and may be arranged in
any suitable pattern to provide the desired mechanical
properties.
[0348] The basis weight of nonwoven materials is usually expressed
in grams per square meter (gsm). The basis weight of a single layer
nonwoven material can range from about 8 gsm to about 100 gsm,
depending on the ultimate use of the material. For example, each
layer of a laminate may have a basis weight from about 8 to about
40 gsm or from about 8 to about 30 gsm. The basis weight of a
multi-layer material is the combined basis weight of the
constituent layers and any other added components. The basis weight
of multi-layer materials of interest herein can range from about 20
gsm to about 150 gsm, depending on the ultimate use of the
material.
[0349] Where material webs of the present invention comprise a film
layer, any suitable film may be utilized. Exemplary films are
discussed in U.S. Pat. Nos. 7,410,683; 8,440,286 and 8,697,218.
[0350] Forms of the present invention are contemplated where
fillers--having a higher thermal conductivity than the polymer
material--are included to the polymer material. Exemplary fillers
include inorganic fillers such as calcium carbonate, which can have
a higher thermal conductivity than the polymer matrix (e.g., than
polypropylene), allowing faster and more homogeneous transfer of
heat within the fiber matrix. This can allow for more benefit from
the heat already applied in the processing of the material web and,
if any, may increase the effect of heat treatment after the
production of the material web. The particle size of the filler may
be important for the observed effect. In one embodiment, the
average particle size of the filler is hence 10 .mu.m or smaller,
preferably 1 .mu.m or smaller (ISO 14688). The material may also be
chosen to exhibit a thermal conductivity at room temperature of 1
Wm-1K-1 or greater or more, 2.0 Wm-1K-1 or more (DIN EN 12664). In
some forms, the thermal conductivity could be 2.7 Wm-1K-1, which
approximately corresponds to that of CaCO3. Suitable CaCO3 can in
one example be either ground CaCO3 (GCC) or precipitated CaCO3, or
a combination thereof. For example, the CaCO3 can be micro-CaCO3
(GCC) having a Plus 325 Mesh of 0.002% and/or mean particle size of
1.6 microns and/or specific surface area of 4.5 m2/g. Such material
is, for example, contained in a masterbatch under the trade name
"Fiberlink 201S" from A. Schulman. In another example, the CaCO3
can be nano-CaCO3 (PCC) having a residue on sieve 45 micron<250
ppm and/or mean particle diameter of 0.07-0.13 microns and/or
specific surface area 16 m2/g. Such material is, for example, found
under the tradename SOCAL.RTM. U1S2 from Imerys Group. The use of
CaCO.sub.3 at around 10 percent by weight boosted blooming in
materials tested. However, because of its size, CaCO.sub.3 may not
be appropriate for other types of material processing, e.g.
meltblowing.
[0351] Forms of the present invention are contemplated where a
nucleating agent(s) is (are) included in the polymer matrix. A
nucleating agent can increase the number of sites where
crystallites begin to form, thereby decreasing the area the
crystallites have to grow before they will impinge on each other.
Accordingly, the crystallites will be dimensionally smaller and the
additive will have a shorter distance to travel before it reaches
the fiber surface. In general melt additives may only be able to
migrate through the amorphous domains of the polymeric matrix at
room temperature, but dependent on the degree of crystallinity (or
degree of amorphousness), the geometry and size of the amorphous
regions, as well as the conformation and size of the migratory
additive, the additive may not be able to migrate effectively at
all, as it can be too constricted to move. So it is believed that
the less constricted the path composed of the amorphous phase, the
more additive will be able to reach the surface before the polymer
has recrystallized. Nucleating agents can help to drive more or
faster blooming of a melt-additive. In the specific case of
hydrophobic or hydrophilic melt additives, the nucleating agent can
create a more intensive hydrophobic or hydrophilic effect from the
respective melt-additives than without the nucleating agent.
Additionally, the provision of a nucleating agent can reduce the
level of melt additive needed for effective blooming. This can be
cost beneficial as less melt additive may be utilized to
potentially achieve the same blooming effect to that achievable
with higher levels of melt additive sans the nucleating agent.
[0352] Suitable nucleating agents can be both inorganic or organic,
and insoluble and soluble in the polymer matrix. In some forms, the
nucleating agent comprises a nonitol, trisamide and/or a sorbitol
based nucleating agent. Specific but non-limiting examples are:
organic nucleation agents such as Millad NX 8000 or (in its new
trade name) NX UltraClear GP110B from the Milliken company.
Trisamide can be obtained, for example, from Irgaclear XT 386 or
any masterbatches containing that active component. An example of
an effective inorganic nucleating agent is CaCO3, or other and
especially nano-clay or nano-scale mineral molecules.
[0353] Where finer fibers than spunbond are being produced, a
suitable nucleating agent is NX UltraClear GP110B. The NX
UltraClear GP110B may be used from between 2 weight percent to 4
weight percent of NX UltraClear GP110B masterbatch (containing 10
percent of the active). The nucleating agent can boost blooming of
the melt additive. Weight percentages of 0.5 weight percent to
about 1.0 weight percent may be utilized; however, it is believed
that such concentrations would be less effective than the former
range based upon testing of an equivalent nucleating agent NX10
also from Milliken.
[0354] Including branched polymers and/or random co-polymers to the
polymer material may result in a polymeric matrix that inherently
allows the additive to move more freely and less constricted and
therefore faster. Diffusivity may be promoted, e.g., by
using/adding branched polymers or random-copolymers as/to the
polymer material. As an example, bi-component technology may be
utilized where the additive is added to only (or predominantly) the
polymer feeds eventually forming at least the predominant part of
the outermost area of the fibers e.g. sheath in a core-sheath
configuration.
Disposable Absorbent Articles
[0355] The material webs of the present invention may comprise any
suitable portion of a disposable absorbent article. Some suitable
examples, include a topsheet, backsheet, barrier cuff, intermediate
layers between the topsheet and an absorbent core and/or
intermediate layers between the backsheet and the absorbent
core.
[0356] Referring to FIG. 17, an absorbent article 1710 which may
utilize the material webs described herein may be a sanitary
napkin/feminine hygiene pad. As shown, the sanitary napkin 1710 may
comprise a liquid permeable topsheet 1714, a liquid impermeable, or
substantially liquid impermeable, backsheet 1716, and an absorbent
core 1718 positioned intermediate the topsheet 1714 and the
backsheet 1716. The sanitary napkin 1710 may comprise wings 1720
extending outwardly with respect to a longitudinal axis 1780 of the
sanitary napkin 1710. The sanitary napkin 1710 may also comprise a
lateral axis 1790. The wings 1720 may be joined to the topsheet
1714, the backsheet 1716, and/or the absorbent core 1718. The
sanitary napkin 1710 may also comprise a front edge 1722, a rear
edge 1724 longitudinally opposing the front edge 1722, a first side
edge 1726, and a second side edge 1728 laterally opposing the first
side edge 1726. The longitudinal axis 1780 may extend from a
midpoint of the front edge 1722 to a midpoint of the rear edge
1724. The lateral axis 1790 may extend from a midpoint of the first
side edge 1726 to a midpoint of the second side edge 1728. The
sanitary napkin 1710 may also be provided with additional features
commonly found in sanitary napkins as is known in the art. In some
forms of the present invention, the wings may be provided with
zones of extensibility as described in U.S. Pat. No. 5,972,806.
[0357] Any suitable absorbent core known in the art may be
utilized. The absorbent core 1718 may be any absorbent member which
is generally compressible, conformable, non-irritating to the
wearer's skin, and capable of absorbing and retaining liquids such
as urine, menses, and/or other body exudates. The absorbent core
1718 may be manufactured from a wide variety of liquid-absorbent
materials commonly used in disposable absorbent articles such as
comminuted wood pulp which is generally referred to as airfelt. The
absorbent core 1718 may comprise superabsorbent polymers (SAP) and
less than 15%, less than 10%, less than 5%, less than 3%, or less
than 1% of airfelt, or be completely free of airfelt. Examples of
other suitable absorbent materials comprise creped cellulose
wadding, meltblown polymers including coform, chemically stiffened,
modified or cross-linked cellulosic fibers, tissue including tissue
wraps and tissue laminates, absorbent foams, absorbent sponges,
superabsorbent polymers, absorbent gelling materials, or any
equivalent material or combinations of materials.
[0358] The configuration and construction of the absorbent core
1718 may vary (e.g., the absorbent core may have varying caliper
zones, a hydrophilic gradient, a superabsorbent gradient, or lower
average density and lower average basis weight acquisition zones;
or may comprise one or more layers or structures). In some forms,
the absorbent core 1718 may comprise one or more channels, such as
two, three, four, five, or six channels.
[0359] The absorbent core 1718 of the present disclosure may
comprise one or more adhesives, for example, to help immobilize the
SAP or other absorbent materials within a core wrap and/or to
ensure integrity of the core wrap, in particular when the core wrap
is made of two or more substrates. The core wrap may extend to a
larger area than required for containing the absorbent material(s)
within.
[0360] Absorbent cores comprising relatively high amounts of SAP
with various core designs are disclosed in U.S. Pat. No. 5,599,335
to Goldman et al., EP 1,447,066 to Busam et al., WO 95/11652 to
Tanzer et al., U.S. Pat. Publ. No. 2008/0312622A1 to Hundorf et
al., and WO 2012/052172 to Van Malderen.
[0361] Other forms and more details regarding channels and pockets
that are free of, or substantially free of absorbent materials,
such as SAP, within absorbent cores are discussed in greater detail
in U.S. Patent Application Publication Nos. 2014/0163500,
2014/0163506, and 2014/0163511, all published on Jun. 12, 2014.
[0362] The absorbent article 1710 may comprise additional layers
between the top sheet 1714 and the absorbent core 1718. For
example, the absorbent article 1710 may comprise a secondary
topsheet and/or an acquisition layer positioned between the
topsheet 1714 and the absorbent core 1718.
[0363] The backsheet can comprise a liquid impervious film. The
backsheet can be impervious to liquids (e.g., body fluids) and can
be typically manufactured from a thin plastic film. However,
typically the backsheet can permit vapours to escape from the
disposable article. In an embodiment, a microporous polyethylene
film can be used for the backsheet. A suitable microporous
polyethylene film is manufactured by Mitsui Toatsu Chemicals, Inc.,
Nagoya, Japan and marketed in the trade as PG-P.
[0364] One suitable material for the backsheet can be a liquid
impervious thermoplastic film having a thickness of from about
0.012 mm (0.50 mil) to about 0.051 mm (2.0 mils), for example
including polyethylene or polypropylene. Typically, the backsheet
can have a basis weight of from about 5 g/m.sup.2 to about 35
g/m.sup.2. However, it should be noted that other flexible liquid
impervious materials may be used as the backsheet. Herein,
"flexible" refers to materials which are compliant and which will
readily conform to the general shape and contours of the wearer's
body.
[0365] The backsheet can be typically positioned adjacent an
outer-facing surface of the absorbent core and can be joined
thereto by any suitable attachment device known in the art. For
example, the backsheet may be secured to the absorbent core by a
uniform continuous layer of adhesive, a patterned layer of
adhesive, or an array of separate lines, spirals, or spots of
adhesive. Illustrative, but non-limiting adhesives, include
adhesives manufactured by H. B. Fuller Company of St. Paul, Minn.,
U.S.A., and marketed as HL-1358J. An example of a suitable
attachment device including an open pattern network of filaments of
adhesive is disclosed in U.S. Pat. No. 4,573,986 entitled
"Disposable Waste-Containment Garment", which issued to Minetola et
al. on Mar. 4, 1986. Another suitable attachment device including
several lines of adhesive filaments swirled into a spiral pattern
is illustrated by the apparatus and methods shown in U.S. Pat. No.
3,911,173 issued to Sprague, Jr. on Oct. 7, 1975; U.S. Pat. No.
4,785,996 issued to Ziecker, et al. on Nov. 22, 1978; and U.S. Pat.
No. 4,842,666 issued to Werenicz on Jun. 27, 1989. Alternatively,
the attachment device may include heat bonds, thermal fusion bonds,
pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any
other suitable attachment device or combinations of these
attachment devices. The backsheet may be additionally secured to
the topsheet by any of the above-cited attachment
devices/methods.
[0366] Still another example of a disposable absorbent article
which may utilize the material webs of the present invention are
diapers which include non-refastenable pants, re-fastenable pants
and/or re-fastenable diapers. Diapers have can have a similar
construction to that of sanitary napkins. An exemplary diaper is
described below.
[0367] Referring to FIG. 18, a plan view of an example absorbent
article that is a diaper 1900 in its flat-out, uncontracted state
(i.e., with elastic induced contraction pulled out) with portions
of the structure being cut-away to more clearly show the
construction of the diaper 1900 and with its wearer-facing surface
toward the viewer. This diaper is shown for illustration purpose
only as the present disclosure may be used for making a wide
variety of diapers and other absorbent articles.
[0368] The absorbent article may comprise a liquid permeable
topsheet 1924, a liquid impermeable backsheet 1925, an absorbent
core 1928 positioned at least partially intermediate the topsheet
1924 and the backsheet 1925, and barrier leg cuffs 1934. The
absorbent article may also comprise a liquid management system
("LMS") 1950 (shown in FIG. 19), which, in the example represented,
comprises a distribution layer 1954 and an acquisition layer 1952
that will both be further discussed below. In various forms, the
acquisition layer 1952 may instead distribute bodily exudates and
the distribution layer 1954 may instead acquire bodily exudates or
both layers may distribute and/or acquire bodily exudates. The LMS
1950 may also be provided as a single layer or two or more layers.
The absorbent article may also comprise elasticized gasketing cuffs
1932 joined to the chassis of the absorbent article, typically via
the topsheet and/or backsheet, and substantially planar with the
chassis of the diaper.
[0369] The Figures also show typical taped diaper components such
as a fastening system comprising adhesive tabs 1942 or other
mechanical fasteners attached towards the rear edge of the
absorbent article 1900 and cooperating with a landing zone on the
front of the absorbent article 1900. The absorbent article may also
comprise other typical elements, which are not represented, such as
a rear elastic waist feature and a front elastic waist feature, for
example.
[0370] The absorbent article 1900 may comprise a front waist edge
1910, a rear waist edge 1912 longitudinally opposing the front
waist edge 1910, a first side edge 1903, and a second side edge
1904 laterally opposing the first side edge 1903. The front waist
edge 1910 is the edge of the absorbent article 1900 which is
intended to be placed towards the front of the user when worn, and
the rear waist edge 1912 is the opposite edge. Together the front
waist edge 1910 and the rear waist edge form waist opening when the
absorbent article 1900 is donned on a wearer. The absorbent article
1900 may have a longitudinal axis 1980 extending from the lateral
midpoint of the front waist edge 1910 to a lateral midpoint of the
rear waist edge 1912 of the absorbent article 1900 and dividing the
absorbent article 1900 in two substantially symmetrical halves
relative to the longitudinal axis 1980, with article placed flat
and viewed from the wearer-facing surface as illustrated FIG. 19.
The absorbent article may also have a lateral axis 1990 extending
from the longitudinal midpoint of the first side edge 1903 to the
longitudinal midpoint of the second side edge 1904. The length L of
the absorbent article 1900 may be measured along the longitudinal
axis 1980 from the front waist edge 1910 to the rear waist edge
1912. The crotch width of the absorbent article 1900 may be
measured along the lateral axis 1990 from the first side edge 1903
to the second side edge 1904. The absorbent article 1900 may
comprise a front waist region 1905, a rear waist region 1906, and a
crotch region 1907. The front waist region, the rear waist region,
and the crotch region each define 1/3 of the longitudinal length of
the absorbent article. Front and back portions may also be defined
on opposite sides of the lateral axis 1990.
[0371] The topsheet 1924, the backsheet 1925, the absorbent core
1928, and the other article components may be assembled in a
variety of configurations, in particular by gluing or heat
embossing, for example. Example diaper configurations are described
generally in U.S. Pat. Nos. 3,860,003, 5,221,274, 5,554,145,
5,569,234, 5,580,411, and 6,004,306.
[0372] The absorbent core 1928 may comprise an absorbent material
comprising 75% to 100%, at least 80%, at least 85%, at least 90%,
at least 95%, or at least 99%, all by weight, of the absorbent
material, specifically reciting all 0.1% increments within the
above-specified ranges and all ranges formed therein or thereby,
and a core wrap enclosing the absorbent material. The core wrap may
typically comprise two materials, substrates, or nonwoven materials
16 and 16' for the top side and bottom side of the core.
[0373] The absorbent core 1928 may comprises one or more channels,
represented in FIG. 19 as the four channels 1926, 1926' and 1927,
1927'. Additionally or alternatively, the LMS 1950 may comprises
one or more channels, represented in FIGS. 18-20 as channels 1949,
1949'. In some forms, the channels of the LMS 1950 may be
positioned within the absorbent article 1900 such they aligned
with, substantially aligned with, overlap, or at least partially
overlap, the channels of the absorbent core 1928. These and other
components of the absorbent articles will now be discussed in more
details.
[0374] The topsheet 1924 is the part of the absorbent article that
is directly in contact with the wearer's skin. The topsheet 1924
may be joined to the backsheet 1925, the core 1928 and/or any other
layers as is known to those of skill in the art. Usually, the
topsheet 1924 and the backsheet 1925 are joined directly to each
other in some locations (e.g., on or close to the periphery of the
article) and are indirectly joined together in other locations by
directly joining them to one or more other elements of the
absorbent article 1900.
[0375] The backsheet 1925 is generally that portion of the
absorbent article 1900 positioned adjacent the garment-facing
surface of the absorbent core 1928 and which prevents, or at least
inhibits, the bodily exudates absorbed and contained therein from
soiling articles such as bedsheets and undergarments. The backsheet
1925 is typically impermeable, or at least substantially
impermeable, to liquids (e.g., urine, running BM), but permeable to
vapors to allow the diaper to "breath". The backsheet may, for
example, be or comprise a thin plastic film such as a thermoplastic
film having a thickness of about 0.012 mm to about 0.051 mm.
Example backsheet films include those manufactured by Tredegar
Corporation, based in Richmond, Va., and sold under the trade name
CPC2 film. Other suitable backsheet materials may include
breathable materials which permit vapors to escape from the
absorbent article 1900 while still preventing, or at least
inhibiting, bodily exudates from passing through the backsheet
1925. Example breathable materials may include materials such as
woven webs, nonwoven webs, and composite materials such as
film-coated nonwoven webs, microporous films, and monolithic
films.
[0376] The backsheet 1925 may be joined to the topsheet 1924, the
absorbent core 1928, and/or any other element of the absorbent
article 1900 by any attachment methods known to those of skill in
the art. Suitable attachment methods are described above with
respect to methods for joining the topsheet 1924 to other elements
of the absorbent article 1900.
[0377] As used herein, the term "absorbent core" refers to the
individual component of the absorbent article having the most
absorbent capacity and that comprises an absorbent material. The
absorbent core may comprise a core wrap or core bag (hereafter
"core wrap") enclosing the absorbent material. The term "absorbent
core" does not include the LMS or any other component of the
absorbent article which is not either integral part of the core
wrap or placed within the core wrap. The absorbent core may
comprise, consist essentially of, or consist of, a core wrap,
absorbent material as defined below, and glue enclosed within the
core wrap. Pulp or air-felt may also be present within the core
wrap and may form a portion of the absorbent material. The
absorbent core periphery, which may be the periphery of the core
wrap, may define any suitable shape, such as a "T," "Y,"
"hour-glass," or "dog-bone" shape, for example. An absorbent core
periphery having a generally "dog bone" or "hour-glass" shape may
taper along its width towards the middle or "crotch" region of the
core. In this way, the absorbent core may have a relatively narrow
width in an area of the absorbent core intended to be placed in the
crotch region of an absorbent article.
[0378] The absorbent core 1928 of the present disclosure may
comprise an absorbent material with a high amount of superabsorbent
polymers (herein abbreviated as "SAP") enclosed within a core wrap.
The SAP content may represent 70% to 100% or at least 70%, 75%,
80%, 85%, 90%, 95%, 99%, or 100% by weight of the absorbent
material contained in the core wrap. The SAP useful with the
present disclosure may include a variety of water-insoluble, but
water-swellable polymers capable of absorbing large quantities of
fluids. The core wrap is not considered as absorbent material for
the purpose of assessing the percentage of SAP in the absorbent
core. The remainder of the absorbent material in the core 1928 may
be air-felt.
[0379] "Absorbent material" means a material which has some
absorbency property or liquid retaining properties, such as SAP,
cellulosic fibers as well as synthetic fibers. Typically, glues
used in making absorbent cores have no absorbency properties and
are not considered as absorbent material. The SAP content may be
higher than 80%, for example at least 85%, at least 90%, at least
95%, at least 99%, and even up to and including 100% of the weight
of the absorbent material contained within the core wrap, as stated
above. This provides a relatively thin core compared to
conventional cores typically comprising between 40-60% SAP, for
example, and high content of cellulose fibers or airfelt. The
absorbent material may comprise less than 15% or less than 10%
weight percent of natural or synthetic fibers, less than 5% weight
percent, less than 3% weight percent, less than 2% weight percent,
less than 1% weight percent, or may even be substantially free of,
or free of, natural and/or synthetic fibers, specifically reciting
all 0.1% increments within the specified ranges and all ranges
formed therein or thereby. The absorbent material may comprise
little or no airfelt (cellulose) fibers, in particular the
absorbent core may comprise less than 15%, 10%, 5%, 3%, 2%, 1%
airfelt (cellulose) fibers by weight, or may even be substantially
free of, or free of, cellulose fibers, specifically reciting all
0.1% increments within the specified ranges and all ranges formed
therein or thereby.
[0380] The absorbent core 1928 may also comprise a generally planar
top side and a generally planar bottom side. The core 1928 may have
a longitudinal axis 80' corresponding substantially to the
longitudinal axis 80 of the absorbent article, as seen from the top
in a planar view as in FIG. 19. The absorbent material may be
distributed in higher amount towards the front side than towards
the rear side as more absorbency may be required at the front in
particular articles. The absorbent material may have a non-uniform
basis weight or a uniform basis weight across any portion of the
core. The core wrap may be formed by two nonwoven materials,
substrates, laminates, or other materials, 1916, 1916' which may be
at least partially sealed along the sides of the absorbent core.
The core wrap may be at least partially sealed along its front
side, rear side, and two longitudinal sides so that substantially
no absorbent material leaks out of the absorbent core wrap. The
first material, substrate, or nonwoven 1916 may at least partially
surround the second material, substrate, or nonwoven 1916' to form
the core wrap. The first material 1916 may surround a portion of
the second material 1916' proximate to the first and second side
edges 1903 and 1904.
[0381] Cores comprising relatively high amount of SAP with various
core designs are disclosed in U.S. Pat. No. 5,599,335 (Goldman), EP
1,447,066 (Busam), WO 95/11652 (Tanzer), U.S. Pat. Publ. No.
2008/0312622A1 (Hundorf), and WO 2012/052172 (Van Malderen).
[0382] The absorbent material may be one or more continuous layers
present within the core wrap. Alternatively, the absorbent material
may be comprised of individual pockets or stripes of absorbent
material enclosed within the core wrap. In the first case, the
absorbent material may be, for example, obtained by the application
of a single continuous layer of absorbent material. The continuous
layer of absorbent material, in particular of SAP, may also be
obtained by combining two or more absorbent layers having
discontinuous absorbent material application pattern, wherein the
resulting layer is substantially continuously distributed across
the absorbent particulate polymer material area, as disclosed in
U.S. Pat. Appl. Publ. No. 2008/0312622A1 (Hundorf), for example.
The absorbent core 1928 may comprise a first absorbent layer and a
second absorbent layer. The first absorbent layer may comprise the
first material 1916 and a first layer of absorbent material 1960,
which may be 100% or less of SAP. The second absorbent layer may
comprise the second material 1916' and a second layer of absorbent
material 1960, which may also be 100% or less of SAP.
[0383] The fibrous thermoplastic adhesive material may be at least
partially in contact with the absorbent material 1960 in the land
areas and at least partially in contact with the materials 1916 and
1916' in the junction areas. This imparts an essentially
three-dimensional structure to the fibrous layer of thermoplastic
adhesive material, which in itself is essentially a two-dimensional
structure of relatively small thickness, as compared to the
dimension in length and width directions. Thereby, the fibrous
thermoplastic adhesive material may provide cavities to cover the
absorbent material in the land area, and thereby immobilizes this
absorbent material, which may be 100% or less of SAP.
[0384] The core wrap may be made of a single substrate, material,
or nonwoven folded around the absorbent material, or may comprise
two (or more) substrates, materials, or nonwovens which are
attached to another. Typical attachments are the so-called C-wrap
and/or sandwich wrap. In a C-wrap, the longitudinal and/or
transversal edges of one of the substrates are folded over the
other substrate to form flaps. These flaps are then bonded to the
external surface of the other substrate, typically by gluing. Other
techniques may be used to form a core wrap. For example, the
longitudinal and/or transversal edges of the substrates may be
bonded together and then folded underneath the absorbent core 1928
and bonded in that position.
[0385] The core wrap may be at least partially sealed along all the
sides of the absorbent core so that substantially no absorbent
material leaks out of the core. By "substantially no absorbent
material" it is meant that less than 5%, less than 2%, less than
1%, or about 0% by weight of absorbent material escape the core
wrap. The term "seal" is to be understood in a broad sense. The
seal does not need to be continuous along the whole periphery of
the core wrap but may be discontinuous along part or the whole of
it, such as formed by a series of seal points spaced on a line. A
seal may be formed by gluing and/or thermal bonding.
[0386] The core wrap may also be formed by a single substrate which
may enclose as in a parcel wrap the absorbent material and be
sealed along the front side and rear side of the core and one
longitudinal seal.
[0387] The absorbent article 1900 may comprise a pair of barrier
leg cuffs 1934. Each barrier leg cuff may be formed by a piece of
material which is bonded to the absorbent article so it can extend
upwards from the inner surface of the absorbent article and provide
improved containment of liquids and other bodily exudates
approximately at the junction of the torso and legs of the wearer.
The barrier leg cuffs 1934 are delimited by a proximal edge 1964
joined directly or indirectly to the topsheet 1924 and/or the
backsheet 1925 and a free terminal edge 1966, which is intended to
contact and form a seal with the wearer's skin. The barrier leg
cuffs 1934 extend at least partially between the front waist edge
1910 and the rear waist edge 1912 of the absorbent article on
opposite sides of the longitudinal axis 1980 and are at least
present in the crotch region 1907. The barrier leg cuffs 1934 may
be joined at the proximal edge 1964 with the chassis of the
absorbent article by a bond 1965 which may be made by gluing,
fusion bonding, or combination of other suitable bonding processes.
The bond 1965 at the proximal edge 64 may be continuous or
intermittent. The bond 1965 closest to the raised section of the
leg cuffs 1934 delimits the proximal edge 1964 of the standing up
section of the leg cuffs 1934.
[0388] The barrier leg cuffs 1934 may be integral with the topsheet
1924 or the backsheet 1925 or may be a separate material joined to
the absorbent article's chassis. The material of the barrier leg
cuffs 1934 may extend through the whole length of the diapers but
may be "tack bonded" to the topsheet 1924 towards the front waist
edge 1910 and rear waist edge 1912 of the absorbent article so that
in these sections the barrier leg cuff material remains flush with
the topsheet 1924.
[0389] Each barrier leg cuff 1934 may comprise one, two or more
elastic strands or strips of film 1935 close to this free terminal
edge 1966 to provide a better seal.
[0390] In addition to the barrier leg cuffs 1934, the absorbent
article may comprise gasketing cuffs 1932, which are joined to the
chassis of the absorbent article, in particular to the topsheet
1924 and/or the backsheet 1925 and are placed externally relative
to the barrier leg cuffs 1934. The gasketing cuffs 1932 may provide
a better seal around the thighs of the wearer. Each gasketing leg
cuff may comprise one or more elastic strings 1933 or elastic
elements in the chassis of the absorbent article between the
topsheet 1924 and backsheet 1925 in the area of the leg openings.
All or a portion of the barrier leg and/or gasketing cuffs may be
treated with a lotion or skin care composition. The barrier leg
cuffs may be constructed in a number of different configurations,
including those described in U.S. Pat. App. Publ. No.
2012/0277713.
[0391] In a form, the absorbent article may comprise front ears
1946 and rear ears 1940. The ears may be an integral part of the
chassis, such as formed from the topsheet 1924 and/or backsheet
1925 as side panel. Alternatively, as represented on FIG. 19, the
ears (1946, 1940) may be separate elements attached by gluing, heat
embossing, and/or pressure bonding. The rear ears 1940 may be
stretchable to facilitate the attachment of the tabs 1942 to the
landing zone 1944 and maintain the taped diapers in place around
the wearer's waist. The rear ears 1940 may also be elastic or
extensible to provide a more comfortable and contouring fit by
initially conformably fitting the absorbent article to the wearer
and sustaining this fit throughout the time of wear well past when
absorbent article has been loaded with exudates since the
elasticized ears allow the sides of the absorbent article to expand
and contract.
[0392] One function of the LMS 1950 is to quickly acquire the fluid
and distribute it to the absorbent core 1928 in an efficient
manner. The LMS 1950 may comprise one or more layers, which may
form a unitary layer or may remain as discrete layers which may be
attached to each other. The LMS 1950 may comprise additional
layers: a distribution layer 1954 and/or an acquisition layer 1952
disposed between the absorbent core and the topsheet, but the
present disclosure is not limited to such a configuration.
[0393] The LMS 1950 may comprise SAP as this may slow the
acquisition and distribution of the fluid. In other forms, the LMS
may be substantially free (e.g., 80%, 85%, 90%, 95%, or 99% free
of) or completely free of SAP. The LMS may also comprise one or
more of a variety of other suitable types of materials, such as
opened-cell foam, air-laid fibers, or carded, resin bonded nonwoven
materials, for example. Suitable example LMSs are described in WO
2000/59430 (Daley), WO 95/10996 (Richards), U.S. Pat. No. 5,700,254
(McDowall), and WO 02/067809 (Graef), for example. The distribution
layer 1954 may comprise at least 50% or more by weight of
cross-linked cellulose fibers, for example. The cross-linked
cellulosic fibers may be crimped, twisted, or curled, or a
combination thereof including crimped, twisted, and curled. This
type of material is disclosed in U.S. Pat. Publ. No. 2008/0312622
A1 (Hundorf).
[0394] The acquisition layer 1952 may be disposed, for example,
between the distribution layer 1954 and the topsheet 1924. The
acquisition layer 1952 may be or may comprise a non-woven material,
such as an SMS or SMMS material, comprising a spunbonded, a
melt-blown and a further spunbonded layer or alternatively a carded
chemical-bonded nonwoven. The acquisition layer 1952 may comprise
air or wet-laid cellulosic, cross-linked cellulosic, or synthetic
fibers, or blends thereof. The acquisition layer 1952 may comprise
a roll-stock web of synthetic fibers (which may be processed to
increase void space, such as by solid state formation), or a
combination of synthetic and cellulosic fibers, bonded together to
form a highloft material. Alternatively, the acquisition layer 1952
may comprise absorbent open cell foam. The nonwoven material may be
latex bonded.
[0395] The LMS 1950 of the absorbent article 1900 may comprise
channels that may generally enable better conformation of the
absorbent article to the wearer's anatomy, leading to increased
freedom-of-movement and reduced gapping. One or more of the
channels of the LMS 1950 may be configured to work in concert with
various channels in the absorbent core 1928, as discussed above.
Furthermore, channels in the LMS 1950 may also provide increased
void space to hold and distribute urine, BM or other bodily
exudates within the absorbent article, leading to reduced leakage
and skin contact. Channels in the LMS 1950 may also provide
internal serviceable indicia, especially when highlighted via
physical differences in texture, color, and/or pattern, to
facilitate achieving the correct alignment of the absorbent article
on a wearer. Thus, such physical differences may be, for example,
visually and/or tactilely noticeable.
[0396] As stated previously, the material webs of the present
invention may be utilized as a topsheet for a disposable absorbent
article, examples of which include the sanitary napkin 1710 and
diaper 1900 discussed heretofore.
[0397] The material webs of the present disclosure may be used as
components of absorbent articles. More than one material web may be
used in a single absorbent article. In such a context, the material
webs may form at least a portion of: a topsheet; a topsheet and an
acquisition layer; a topsheet and a distribution layer; an
acquisition layer and a distribution layer; a topsheet, an
acquisition layer, and a distribution layer; an outer cover; a
backsheet; an outer cover and a backsheet, wherein a film
(non-apertured layer) forms the backsheet and a nonwoven web forms
the outer cover; a leg cuff; an ear or side panel; a fastener; a
waist band; belt or any other suitable portion of an absorbent
article. The number of strata in a nonwoven web may also be
determined by the nonwoven laminates' particular use.
[0398] In some forms, additional layers may be positioned between
the topsheet and the absorbent core. For example, a secondary
topsheet, acquisition layer, and/or distribution layer, each of
which are known in the art, may be positioned between the topsheet
and the absorbent core of the absorbent article.
Arrays of Absorbent Articles
[0399] As mentioned heretofore, material webs of the present
invention may be utilized in a plurality of absorbent articles.
Forms of the present invention are contemplated where an array of
absorbent articles, each comprising a topsheet, backsheet, and an
absorbent core disposed therebetween comprise material webs of the
present invention. The array comprises a first plurality of
absorbent articles comprising a first material web. The first
material web comprises a first plurality of melt additive bloom
areas. The first material web may form at least a portion of each
of the first plurality of absorbent articles, e.g. topsheet,
backsheet, absorbent core.
[0400] The array further comprises a second plurality of absorbent
articles. Each of the second plurality of absorbent articles
comprises a second material web which forms a portion of at least
one of the topsheet, backsheet and/or absorbent core. The second
material web may comprise a second plurality of melt additive bloom
areas. The first plurality of melt additive bloom areas and the
second plurality of bloom areas may be different. For example, the
first plurality of melt additive areas may comprise a hydrophobic
composition while the second plurality of melt additive areas
comprise a hydrophilic composition. In such forms, the first
material web may form a portion of the topsheet of the first
plurality of absorbent articles, and the second material web may
form a portion of the topsheet of the second plurality of absorbent
articles. In some forms, the first plurality of absorbent articles
may be the same type of article as the second plurality of
absorbent articles, e.g. sanitary pads. In other forms, the first
plurality of absorbent articles may be different than the second
plurality of absorbent articles, e.g. diapers versus sanitary pads.
Still in other forms, the first material web may form a portion of
the first plurality of absorbent articles which is different than
what the second material web forms for the second plurality of
absorbent articles, e.g. backsheet versus topsheet.
[0401] In some forms of the present invention, the first material
web may comprise a different combination of discontinuities than
the second material web. For example, the first material may
comprise a combination of apertures and tunnel tufts while the
second material web comprises a nested tufts and apertures. In some
forms, the first plurality of absorbent articles may comprise a
different discontinuity or combination thereof than the second
plurality of absorbent articles. In such forms, the melt additive
bloom areas for the first plurality of absorbent articles may
comprise a different composition than the melt additive bloom areas
for the second plurality of absorbent articles. Additionally, in
such forms, the first plurality of absorbent articles may be
different than the second plurality of absorbent articles, e.g.
diaper versus sanitary pad.
[0402] Forms of the present invention are contemplated where the
array comprises additional pluralities of absorbent articles. Such
additional pluralities may comprise material webs of the present
invention. These material webs may be different than the first
material web and/or second material web.
[0403] As another example, forms of the present invention are
contemplated where a nonwoven comprises a hydrophobic melt
additive. The nonwoven comprises a hydrophilic fiber composition or
a fiber composition which is more hydrophilic than the melt
additive. In such forms, the nonwoven may be processed such that a
plurality of discrete melt additive bloom areas are provided on the
nonwoven. The melt additive bloom areas may correspond to the
distal ends of at least one of tufts or corrugations. The nonwoven,
in some forms, may further comprise apertures, embossments, and/or
fusion bonds. In some forms, the apertures may be provided in an
intermediate zone, while the tufts are provided in laterally
outboard zones from the intermediate zone. The fusion bonds and/or
embossments may be in the intermediate zone and/or in the laterally
outboard zones. In some forms, the embossments may be limited to
the intermediate zone while the fusion bonds are in the
intermediate zone and in the lateral zones.
[0404] As yet another example, forms of the present invention are
contemplated where a nonwoven comprises a hydrophilic melt
additive. The nonwoven comprises a hydrophobic fiber composition or
a fiber composition which is more hydrophobic than the melt
additive. In such forms, the nonwoven may be processed such that a
plurality of discrete melt additive bloom areas are provided on the
nonwoven. The melt additive bloom areas may correspond to the
undeformed regions of the material web. The nonwoven web may
further comprise a plurality of tufts and/or corrugations. The
nonwoven web may further comprise at least one of fusion bonds,
embossments, and/or apertures.
[0405] As yet another example, forms of the present invention are
contemplated where a film comprises a melt additive. The film may
be subjected to processing which applies thermal energy across the
film thereby creating promoting the creation of melt additive bloom
areas. The melt additive bloom area may comprise a hydrophobic
composition. Forms of this invention are contemplated where the
film further comprises at least one of apertures, embossments,
tufts, corrugations, fusion bonds, and/or distal end/land area
bonds. Additionally, such films may be utilized in the context of a
portion of a backsheet which is air permeable but impervious to
liquid.
[0406] As yet another example, forms of the present invention are
contemplated where a material web comprising a melt additive is
subjected to thermal energy application across the entirety of the
web. The material web may be a nonwoven and the melt additive may
comprise a hydrophobic composition. The nonwoven web may further
comprise apertures. Additionally, the nonwoven web may further
comprise at least one of embossments, tufts, corrugations, or
fusion bonds. The apertures, embossments, tufts, corrugations
and/or fusion bonds may be arranged in zones as described
herein.
Packaging
[0407] In some forms of the present invention, the material webs of
the present invention may be utilized as packaging. For example, as
packaging of disposable absorbent articles. In such forms, the
material web may be provided with discrete melt additive bloom
areas as described herein. The melt additive bloom areas may alter
the coefficient of friction in a plurality of localized areas. In
some forms, the melt additive bloom areas may increase the
coefficient of friction to provide for better grip of the
packaging. In some forms, the melt additive bloom areas may form
anti-stick regions to control fluid dispensing. In such forms,
hydrophobic compositions may be leveraged due to its liquid
repelling effect that gives a cleanliness benefit in "critical
areas", e.g. close to an opening for fluid dispensing aperture.
[0408] In some forms, the melt additive bloom areas may alter the
coefficient of friction of discrete portions of packaging, e.g. by
providing softness, to reinforce the haptic perception of a 3D
structure on the package. In some forms the haptic perception on
the package may correspond to a haptic perception of the product
within the package. In such forms, a consumer may more easily
recognize the package and may associate the "special feel" with the
product.
[0409] In some forms, the melt additive bloom areas can be utilized
to improve the adhesion of ink and/or of glues to the material web,
which as noted above can be packaging for articles. For example
melt additive bloom areas comprising hydrophilic compositions can
increase the surface energy of the material web at the location of
the melt additive bloom areas. The increased surface energy can
increase the adhesion of inks and glues. In contrast, where the
melt additive bloom areas comprise a hydrophobic composition, the
melt additive bloom areas may be selected to occur where ink and/or
glues will not be present. In general, inks and/or glues tend to
wash off of hydrophobic compositions/substrates.
[0410] Forms of the present invention are contemplated where the
packaging comprises a composition having a higher Tg, e.g.
polystyrene--100 degrees C., polycarbonate--145 degrees C. In such
forms, as noted previously, it is believed that suitable melt
additives are much easier to find given the high Tg.
Tests
Glass Transition Temperature and Melting Temperature
[0411] Tg and melting point are determined in accordance with ASTM
D3418-15 for both the base matrix polymer and the neat
melt-additive. When melt additive is not directly available, it can
be collected from heat treated substrate using the extraction
described in "Solvent Wash Procedure".
Surface Tension of a Liquid
[0412] The surface tension of a liquid is determined by measuring
the force exerted on a platinum Wilhelmy plate at the air-liquid
interface. A Kruss tensiometer K11 or equivalent is used.
(Available by Kruss USA (www.kruss.de)). The test is operated in a
laboratory environment at 23.+-.2.degree. C. and 50.+-.5% relative
humidity. The test liquid is placed into the container given by the
manufacturer and the surface tension is recorded by the instrument
and its software.
Surface Tension of a Fiber
Basis Weight Test
[0413] A 9.00 cm2 large piece of web, i.e. 1.0 cm wide by 9.0 cm
long, is cut out of the product, and it needs to be dry and free
from other materials like glue or dust. Samples are conditioned at
23.degree. Celsius (.+-.2.degree. C.) and at a relative humidity of
about 50% (.+-.5%) for 2 hours to reach equilibrium. The weight of
the cut web pieces is measured on a scale with accuracy to 0.0001
g. The resulting mass is divided by the specimen area to give a
result in g/m2 (gsm). Repeat for at least 20 specimens for a
particular sample from 20 identical products, if the product and
component is large enough, more than one specimen can be obtained
from each product. An example of a sample is the left diaper cuff
in a bag of diapers, and 10 identical diapers are used to cut out
two 9.00 cm2 large specimens of cuff web from the left side of each
diaper for a total of 20 specimens of "left-side cuff nonwoven." If
the local basis weight variation test is done, those same samples
and data are used for calculating and reporting the average basis
weight.
Low Surface Tension Fluid Strikethrough Time Test
[0414] The low surface tension fluid strikethrough time test is
used to determine the amount of time it takes a specified quantity
of a low surface tension fluid, discharged at a prescribed rate, to
fully penetrate a sample of a web (and other comparable barrier
materials) which is placed on a reference absorbent pad. As a
default, this is also called the 32 mN/m Low Surface Tension Fluid
Strikethrough Test because of the surface tension of the test fluid
and each test is done on two layers of the nonwoven sample simply
laid on top of each other.
[0415] For this test, the reference absorbent pad is 5 plies of
Ahlstrom grade 989 filter paper (10 cm.times.10 cm) and the test
fluid is a 32 mN/m low surface tension fluid.
Scope
[0416] This test is designed to characterize the low surface
tension fluid strikethrough performance (in seconds) of webs
intended to provide a barrier to low surface tension fluids, such
as runny BM, for example.
Equipment
[0417] Lister Strikethrough Tester: The instrumentation is like
described in EDANA ERT 153.0-02 section 6 with the following
exception: the strike-through plate has a star-shaped orifice of 3
slots angled at 60 degrees with the narrow slots having a 10.0 mm
length and a 1.2 mm slot width. This equipment is available from
Lenzing Instruments (Austria) and from W. Fritz Metzger Corp (USA).
The unit needs to be set up such that it does not time out after
100 seconds.
[0418] Reference Absorbent Pad: Ahlstrom Grade 989 filter paper, in
10 cm.times.10 cm areas, is used. The average strikethrough time is
3.3+0.5 seconds for 5 plies of filter paper using the 32 mN/m test
fluid and without the web sample. The filter paper may be purchased
from Empirical Manufacturing Company, Inc. (EMC) 7616 Reinhold
Drive Cincinnati, Ohio 45237.
[0419] Test Fluid: The 32 mN/m surface tension fluid is prepared
with distilled water and 0.42+/-0.001 g/liter Triton-X 100. All
fluids are kept at ambient conditions.
[0420] Electrode-Rinsing Liquid: 0.9% sodium chloride (CAS
7647-14-5) aqueous solution (9 g NaCl per 1 L of distilled water)
is used.
Test Procedure
[0421] Ensure that the surface tension is 32 mN/m+/-1 mN/m.
Otherwise remake the test fluid. [0422] Prepare the 0.9% NaCl
aqueous electrode rinsing liquid. [0423] Ensure that the
strikethrough target (3.3+/-0.5 seconds) for the Reference
Absorbent Pad is met by testing 5 plies with the 32 mN/m test fluid
as follows: [0424] Neatly stack 5 plies of the Reference Absorbent
Pad onto the base plate of the strikethrough tester. [0425] Place
the strikethrough plate over the 5 plies and ensure that the center
of the plate is over the center of the paper. Center this assembly
under the dispensing funnel. [0426] Ensure that the upper assembly
of the strikethrough tester is lowered to the pre-set stop point.
[0427] Ensure that the electrodes are connected to the timer.
[0428] Turn the strikethrough tester "on" and zero the timer.
[0429] Using the 5 mL fixed volume pipette and tip, dispense 5 mL
of the 32 mN/m test fluid into the funnel. [0430] Open the magnetic
valve of the funnel (by depressing a button on the unit, for
example) to discharge the 5 mL of test fluid. The initial flow of
the fluid will complete the electrical circuit and start the timer.
The timer will stop when the fluid has penetrated into the
Reference Absorbent Pad and fallen below the level of the
electrodes in the strikethrough plate. [0431] Record the time
indicated on the electronic timer. [0432] Remove the test assembly
and discard the used Reference Absorbent Pad. Rinse the electrodes
with the 0.9% NaCl aqueous solution to "prime" them for the next
test. Dry the depression above the electrodes and the back of the
strikethrough plate, as well as wipe off the dispenser exit orifice
and the bottom plate or table surface upon which the filter paper
is laid. [0433] Repeat this test procedure for a minimum of 3
replicates to ensure the strikethrough target of the Reference
Absorbent Pad is met. If the target is not met, the Reference
Absorbent Pad may be out of spec and should not be used. [0434]
After the Reference Absorbent Pad performance has been verified,
nonwoven web samples may be tested. [0435] Cut the required number
of nonwoven web specimens. For web sampled off a roll, cut the
samples into 10 cm by 10 cm sized square specimens. For web sampled
off of a product, cut the samples into 15 by 15 mm square
specimens. The fluid flows onto the nonwoven web specimen from the
strike through plate. Touch the nonwoven web specimen only at the
edge. [0436] Neatly stack 5 plies of the Reference Absorbent Pad
onto the base plate of the strikethrough tester. [0437] Place the
nonwoven web specimen on top of the 5 plies of filter paper. Two
plies of the nonwoven web specimen are used in this test method. If
the nonwoven web sample is sided (i.e., has a different layer
configuration based on which side is facing in a particular
direction), the side facing the wearer (for an absorbent product)
faces upwards in the test. [0438] Place the strikethrough plate
over the nonwoven web specimen and ensure that the center of the
strikethrough plate is over the center of the nonwoven web
specimen. Center this assembly under the dispensing funnel. [0439]
Ensure that the upper assembly of the strikethrough tester is
lowered to the pre-set stop point. [0440] Ensure that the
electrodes are connected to the timer. Turn the strikethrough
tester "on" and zero the timer. [0441] Run as described above.
[0442] Repeat this procedure for the required number of nonwoven
web specimens. A minimum of 5 specimens of each different nonwoven
web sample is required. The average value is the 32 mN/m low
surface tension strikethrough time in seconds.
Filament Diameter and Denier Test
[0443] The diameter of filaments in a sample of a nonwoven
substrate is determined by using a Scanning Electron Microscope
(SEM) and image analysis software. A magnification of 500 to 10,000
times is chosen such that the filaments are suitably enlarged for
measurement. The samples are sputtered with gold or a palladium
compound to avoid electric charging and vibrations of the filaments
in the electron beam. A manual procedure for determining the
filament diameters is used. Using a mouse and a cursor tool, the
edge of a randomly selected filament is sought and then measured
across its width (i.e., perpendicular to filament direction at that
point) to the other edge of the filament. For non-circular
filaments, the area of the cross-section is measured using the
image analysis software. The effective diameter is then calculated
by calculating the diameter as if the found area was that of a
circle. A scaled and calibrated image analysis tool provides the
scaling to get actual reading in micrometers (.mu.m). Several
filaments are thus randomly selected across the sample of the
nonwoven substrate using the SEM. At least two specimens from the
nonwoven substrate are cut and tested in this manner. Altogether,
at least 100 such measurements are made and then all data is
recorded for statistical analysis. The recorded data is used to
calculate average (mean) of the filament diameters, standard
deviation of the filament diameters, and median of the filament
diameters. Another useful statistic is the calculation of the
amount of the population of filaments that is below a certain upper
limit. To determine this statistic, the software is programmed to
count how many results of the filament diameters are below an upper
limit and that count (divided by total number of data and
multiplied by 100%) is reported in percent as percent below the
upper limit, such as percent below 1 micrometer diameter or
%-submicron, for example.
[0444] If the results are to be reported in denier, then the
following calculations are made.
Filament Diameter in denier=Cross-sectional area (in m2)*density
(in kg/m3)*9000 m*1000 g/kg.
[0445] For round filaments, the cross-sectional area is defined by
the equation:
A=.pi.*(D/2){circumflex over ( )}2.
The density for polypropylene, for example, may be taken as 910
kg/m3.
[0446] Given the filament diameter in denier, the physical circular
filament diameter in meters (or micrometers) is calculated from
these relationships and vice versa. We denote the measured diameter
(in microns) of an individual circular filament as D.
[0447] In case the filaments have non-circular cross-sections, the
measurement of the filament diameter is determined as and set equal
to the hydraulic diameter, as discussed above.
Mass-Average Diameter
[0448] The mass-average diameter of filaments is calculated as
follows:
mass average diameter,
d m .times. a .times. s .times. s = i = 1 n .times. ( m i d i ) i =
1 n .times. m i = i = 1 n .times. ( .rho. V i d i ) i = 1 n .times.
( .rho. V i ) = i = 1 n .times. ( .rho. .pi. .times. d i 2
.differential. x 4 d i ) i = 1 n .times. ( .rho. .pi. .times. d i 2
.differential. x 4 ) = i = 1 n .times. d i 3 i = 1 n .times. d i 2
##EQU00005##
where
[0449] filaments in the sample are assumed to be
circular/cylindrical,
[0450] d.sub.i=measured diameter of the i.sup.th filament in the
sample,
[0451] .differential.x=infinitesimal longitudinal section of
filament where its diameter is measured, same for all the filaments
in the sample,
[0452] m.sub.i=mass of the i.sup.th filament in the sample,
[0453] n=number of filaments whose diameter is measured in the
sample
[0454] .rho.=density of filaments in the sample, same for all the
filaments in the sample
[0455] V.sub.i=volume of the i.sup.th filament in the sample.
[0456] The mass-average filament diameter should be reported in
.mu.m.
Gravimetric Weight Loss Test
[0457] The Gravimetric Weight Loss Test can be used to determine
the amount of lipid ester (e.g., GTS) in a nonwoven substrate of
the present disclosure. One or more samples of the nonwoven
substrate are placed, with the narrowest sample dimension no
greater than 1 mm, into acetone at a ratio of 1 g nonwoven
substrate sample per 100 g of acetone using a refluxing flask
system. First, the sample is weighed before being placed into the
reflux flask, and then the mixture of the sample and the acetone is
heated to 60.degree. C. for 20 hours. The sample is then removed
and air dried for 60 minutes and a final weight of the sample is
determined. The equation for calculating the weight percent lipid
ester in the sample is:
weight % lipid ester=([initial mass of the sample-final mass of the
sample]/[initial mass of the sample]).times.100%.
Presence of a Melt Additive
[0458] Presence of a melt additive (as opposed to a surface
coating) is determined by comparison of non-heat activated
substrate with and without solvent wash. Non activated regions can
be identified using the "Determination of Activated Zones by
FTIR/ATR" method as described previously and excised from the
substrate for analysis. Approximately 2.0 grams needs to be
collected.
[0459] An appropriate solvent is identified which is effective to
dissolve the additive but will not swell the matrix or dissolve any
further additive from the matrix. For GTS in PP, acetone is an
appropriate solvent.
[0460] 1.00 g.+-.0.01 g of the non-heat activated substrate is
weighed into a 500 mL flask and 100 mL of a solvent is added. The
substrate with solvent is then stirred for 30 minutes at 900 rpm at
20.degree. C. The solvent is decanted and the flask is refilled
with a second 100 mL of solvent. The mixture is stirred again for
30 minutes at 900 rpm at 20.degree. C. The solvent is decanted and
the nonwoven is dried overnight at 40.degree. C.
Two melt films are prepared, the first of the non-activated area
unwashed, and a second of the non-activated substrate after solvent
wash, for analysis. Melt film were prepare and analyzed as
described in "Quantification of Total Melt-Additive Concentration
by FTIR". FTIR transmission measurements are made on three (3)
randomly selected sites from each of the washed and non-washed
films to calculate the total concentration. Calculate and record
the arithmetic mean of the triplicates separately, and record as
Concentration Washed and Concentration Unwashed to the nearest
0.1%. Report the ratio of the Unwashed Concentration divided by the
Washed Concentration. A ratio greater than 20 indicates a surface
coating instead of a melt additive was used.
[0461] The FTIR (reflectance and ATR) measurements of melt
additives in a polymer matrix are quantified by peak normalization.
One absorption band is selected which is attributed exclusively to
the melt additive and must be free of interference from other
components or impurities in the sample mixture. This signal is
denoted as E.sub.1. An example is the peak between 1806 cm.sup.-1
and 1660 cm.sup.-1 for the GTS. A second band is selected that
which is attributed exclusively to the polymer matrix and must be
free of interferences from the sample matrix or other impurities in
the sample mixture. The signal is used to normalize for path length
of the specific specimen. This signal is denoted as E.sub.2. An
example is the peak between 985 cm.sup.-1 and 950 cm.sup.-1 for
polypropylene (PP). The FTIR methods described herein are written
directed specifically toward these examples, GTS in PP, but one
skilled in the art, can select analogous peaks to facilitate
analysis of other melt additives and matrixes.
Quantification of Total Melt-Additive Concentration by FTIR
[0462] Total GTS in fibers, is measured using transmission FTIR (a
suitable instrument is the Nicolet 6700, Thermo Scientific, or
equivalent). Calibration was performed using standard films
prepared from known mixtures of GTS in PP and can be used to
quantify the total concentration of GTS on and within a fiber. All
testing is performed in a conditioned room maintained at 23.degree.
C..+-.2C.degree. and 50%.+-.2% relative humidity. Samples are
conditioned under the same conditions for 2 hours prior to
testing.
[0463] Calibration Standards are prepared by mixing the base
polymer (e.g. polypropylene) with the active GTS. A volume of 55
cm.sup.3 of each standard was prepared at a concentration of 0.0%,
0.4%, 1.2%, 2.0%, 4.0%, 12.0% and 20.0% wt/wt of GTS in PP. First
the components were accurately weighed and then placed into a
laboratory tumble mixer (a suitable mixer is the Turbula T2C
available from Willy A. Bachofen AG Maschinenfabrik, or equivalent)
and mixed for 10 min. Next the mixture was added to a laboratory
kneader (a suitable instrument is a Haake Polydrive Mixer, Thermo
Electron GmbH, or equivalent) and kneaded at 180.degree. C. at 10
rpm for 2 min and then again at 60 rpm for an additional 8 min.
After kneading, each mixture is ground (a suitable grinder is the
Wanner C13.20sv or equivalent) before being pressed into a
film.
[0464] One melt film was prepared for each concentration using a
hot press (a suitable press is the Graseby Specac Hot Press, or
equivalent). A standard mixture of 25 mg was placed between two
aluminum foils and melted until the pressing form reached
175.degree. C., pressed for 2.0 min with a 5000 kg weight and then
cooled for 20 min in a water cooled form under no pressure. The
resulting film should have a uniform thickness from 59 .mu.m to 62
.mu.m.
[0465] Transmission FTIR is performed on three different locations
on each calibration film under the following conditions: 64 scans
at a resolution of 1.0 and amplification of 1.0 from 550 to 4000
cm.sup.-1. Background scans are performed before every new
specimen. Two peaks were measured for quantification, one
associated with the PP and the second associated with the GTS.
Using an appropriate software, draw a baseline between 1025
cm.sup.-1 and 950 cm.sup.-1 and measure the vertical drop from
highest peak between 985 cm.sup.-1 and 950 cm.sup.-1 wavenumbers.
Secondly, draw a baseline between 1806 cm.sup.-1 and 1660 cm.sup.-1
and measure the vertical drop from highest peak between those two
wavenumbers.
[0466] Calibration is performed using peak ratio normalization.
Extinction E at a specific wave length .lamda. is defined as:
E(.lamda.)= cd
with c=weight fraction of the absorbing substance; d=thickness of
the radiated sample path length and =coefficient of absorption. For
a two-component-system from substance A and substance B, the
equation would be expressed as:
E(.lamda.)= E.sub.A(A)c.sub.Ad+ .sub.B(.lamda.)c.sub.Bd
To eliminate contribution from the path length, a ratio of the area
of two peaks can be used:
E 1 .function. ( .lamda. ) E 2 .function. ( .lamda. ) = A , 1
.function. ( .lamda. ) c A d p + B , 1 .function. ( .lamda. ) c B d
p A , 2 .function. ( .lamda. ) c A d p + B , 2 .function. ( .lamda.
) c B d p ##EQU00006##
Here E.sub.1 refers to the peak between 1660 and 1806 cm.sup.-1 and
E.sub.2 refers to the peak between 950 and 985 cm.sup.-1. Taking
into account that in a two component system, the single weight
fractions .chi. add up to 1, this gives:
E 1 .function. ( .lamda. ) E 2 .function. ( .lamda. ) = A , 1
.function. ( .lamda. ) c A + B , 1 .function. ( .lamda. ) ( 1 - c A
) A , 2 .function. ( .lamda. ) c A + B , 2 .function. ( .lamda. ) (
1 - c A ) ##EQU00007##
Here the weight fraction of the component is independent of the
path length. Plot the ratio of E.sub.1/E.sub.2 versus the
concentration of the calibration sample and perform a least square
linear fit. The calibration is defined as:
E 1 E 2 = x c initial ##EQU00008##
with x corresponding to a calibration coefficient used to relate
the peak ratio to concentration as % GTS.
[0467] Analysis of a sample nonwoven is performed on 25 mg of
nonwoven excised from the site of interest. Once again a film is
prepared using a hot press with the specimen placed between two
aluminum foils and melted until the pressing form reached
175.degree. C., pressed for 2.0 min with a 5000 kg weight and then
cooled for 20 min in a water cooled form under no pressure. The
resulting film should have a uniform thickness from 59 .mu.m to 62
.mu.m.
[0468] Transmission FTIR is performed on three different locations
on each specimen film using the identical conditions as the
standards. Peak heights in the 1025 cm.sup.-1 and 950 cm.sup.-1
region and 1806 cm.sup.-1 and 1660 cm.sup.-1 region are collected
in like fashion as the standards. The % GTS is calculated using the
calibration coefficient derived above for the three replicates and
reported as the arithmetic average to the nearest 0.1%.
Quantification of Heat Activated Zones Via FTIR/ATR
[0469] GTS surface enrichment on fibers, is measured using
Attenuated Total Reflection (ATR) FTIR (a suitable instrument is
the Nicholet 6700, Thermo Scientific, or equivalent) utilizing both
a Germanium and Diamond crystal. The instrument should be capable
of correcting the ATR signal to match transmission FTIR signal in
accordance with the Advanced ATR Correction Algorithm as described
in Thermo Scientific Application Note 50581. The correction is
applied as specified by the manufactures operating procedures. All
testing is performed in a conditioned room maintained at 23.degree.
C..+-.2C.degree. and 50%.+-.2% relative humidity. Samples are
conditioned under the same conditions for 2 hours prior to
testing.
[0470] Surface enrichment of GTS is measured using FTIR ATR with
both a germanium crystal and diamond crystal. Selecting the
germanium crystal, the specimen is placed on the ATR stage with the
site of interest centered beneath the crystal. The crystal is
pressed against the specimen using the probe to a pressure of 68.9
N/mm.sup.2. 64 scans are collected at a resolution of one data
point per every 0.482 cm.sup.-1, amplification of 1.0, 64 scans are
collected at a resolution of one data point per every 0.482
cm.sup.-1, amplification of 1.0, and 1 bounce measurement type,
between a wave number of 550 cm.sup.-1 to 4000 cm.sup.-1. Between
each measurement the crystal and plunger must be cleaned thoroughly
with isopropanol to prevent carry-over from the previous analyses.
After cleaning wait at least 10 min before starting a new
measurement to ensure no residual isopropanol is present on the
stage and crystal. Background spectra, using the parameters
specified above, were collected every 15 minutes. This background
spectrum is subtracted from each measured sample spectra. A
spectrum is collected on three different but equivalent sites for a
total of 3 spectra. Spectra were repeated using this protocol for
both the germanium and diamond crystals. Two peaks were measured
for quantification, one associated with the PP and the second
associated with the GTS.
[0471] The ATR signal can be corrected to match transmission FTIR
signal by application of the following equation (equation was
derived from Thermo Scientific Application note 50581):
A = - log .times. 10 .times. ( A .times. R .times. T ) = ( log 1
.times. 0 .times. e ) .times. n 2 n 1 .times. E 0 2 cos .times.
.times. .0. .times. d p 2 .times. .alpha. ##EQU00009##
where: A=ATR intensity E.sub.0=electric fields of the evanescent
wave at the boundary .alpha.=absorption coefficient per unit
thickness of sample d.sub.p=penetration depth n.sub.1=refractive
index of the crystal n.sub.2=refractive index of the sample
O=incident angle
[0472] The penetration depth (d.sub.p) for each crystal is
calculated using the following equation:
d p = .lamda. 2 .times. .pi. .times. n Crystal .times. sin 2
.function. ( .0. ) - ( n S .times. a .times. m .times. p .times. l
.times. e n Crystal ) 2 ##EQU00010##
[0473] with n is the refractive index, .theta. is the incident
angle, and A is the incident wave length. The refractive index of
the sample is taken as 1.49 for PP and PE. For example, a germanium
crystal (refractive index=4.0 and incident angle=42.degree.) would
give 0.41 .mu.m penetration and a diamond crystal (refractive
index=2.4 and incident angle=42.degree.) would give 1.51 .mu.m
penetration. Values must be calculated based on the specific
configuration of the instrument used.
[0474] Using an appropriate software draw a baseline between 1806
cm.sup.-1 and 1660 cm.sup.-1 and measure the vertical drop from
highest peak between those two wave numbers. This is E.sub.1.
Secondly, draw a baseline between 1025 cm.sup.-1 and 950 cm.sup.-1
and measure the vertical drop from highest peak between 985
cm.sup.-1 and 950 cm.sup.-1 wave numbers. This is E.sub.2.
Quantification is performed with the calibration coefficient x as
determined herein from the "Quantification of Total Melt-Additive
Concentration by FTIR" method using the equation:
c = ( E 1 E 2 ) .times. / .times. x ##EQU00011##
[0475] The % GTS is calculated for the three replicates and
reported as the arithmetic average to the nearest 0.1%.
Determination of Activated Zones by FTIR/ATR
[0476] Heat activation zones are determined using FTIR with
Attenuated Total Reflection (ATR) (a suitable instrument is the
Nicholet 6700, Thermo Scientific, or equivalent) utilizing both a
Germanium and Diamond crystal. Peak ratios internal to the same
spectrum are proportional to the additive concentration and
therefore can be utilized as a measure to describe the additive
concentration without any further calibration. All testing is
performed in a conditioned room maintained at 23.degree.
C..+-.2C.degree. and 50%.+-.2% relative humidity. Samples are
conditioned under the same conditions for 2 hours prior to
testing.
[0477] Measurements are made by placing the specimen on the ATR
stage with the site of interest centered beneath the crystal. The
crystal is pressed against the specimen using the probe to a
pressure of 68.9 N/mm.sup.2. 64 scans are collected at a resolution
of one data point per every 0.482 cm.sup.-1, amplification of 1.0,
and 1 bounce measurement type, between a wave number of 550
cm.sup.-1 to 4000 cm.sup.-1. Between each measurement the crystal
and plunger must be cleaned thoroughly with isopropanol to prevent
carry-over from the previous analyses. After cleaning wait at least
10 min before starting a new measurement to ensure no residual
isopropanol is present on the stage and crystal. Background
spectra, using the parameters specified above, were collected every
15 minutes. This background spectrum is subtracted from each
measured sample spectra. Using an appropriate software draw a
baseline between 1806 cm.sup.-1 and 1660 cm.sup.-1 and measure the
vertical drop from highest peak between those two wave numbers.
This is E.sub.1. Secondly, draw a baseline between 1025 cm.sup.-1
and 950 cm.sup.-1 and measure the vertical drop from highest peak
between 985 cm.sup.-1 and 950 cm.sup.-1 wave numbers. Measurements
are made at the same site using both the Germanium and Diamond
crystals.
[0478] When the location of heat treated regions and non-heat
treated regions are known a Migration Coefficient (MC) can be
calculated for activated and non-activated areas as follows:
M .times. C n .times. o .times. n - activated = ( ( E 1 .times. /
.times. E 2 ) G .times. e , notactivated .times. .times. area ( E 1
.times. / .times. E 2 ) D .times. ia , notactivated .times. .times.
area - 1 ) .times. 1 .times. 0 .times. 0 .times. % .times. .times.
M .times. C activated = ( ( E 1 .times. / .times. E 2 ) Ge ,
activated .times. .times. area ( E 1 .times. / .times. E 2 ) Dia ,
notactivated .times. .times. area - 1 ) .times. 1 .times. 0 .times.
0 .times. % ##EQU00012##
[0479] With an activated area having an MC equal to or greater than
twice the MC of a non-activated area. But in most cases with
respect to a product heat activated and non-activated areas are not
known, so they need to be determined empirically.
[0480] Select a region of the sample substrate to analyze for heat
activated zones. An x-y test grid 50.0 mm in the machine direction
and 50.0 mm in the cross direction is constructed. Using the
Germanium crystal, an FTIR/ATR spectrum is measured every 5.0 mm
within the test grid from x,y coordinates 1,1 (upper left position)
to coordinate 50,50 (lower right position) for a total of 250
spectra indexed by coordinate. Measure the peak signal for E.sub.1
and E.sub.2 for each spectrum and calculate the ratio of
E.sub.1/E.sub.2 and tabulate into a 50.times.50 Geranium Peak Ratio
(PR) Grid. A 3.times.3 mean filter is applied to the Geranium PR
Grid using the following equation:
P .times. R x , y = P .times. R x + 1 , y + P .times. R x - 1 , y +
P .times. R x , y + P .times. R x , y + 1 + P .times. R x , y - 1 5
##EQU00013##
[0481] A Germanium Results Grid is tabulated, starting at x,y
coordinate 2,2 calculate PR.sub.2,2 then increment x by 1 and
calculate PR.sub.3,2 and so forth until coordinate 49,2. Next
increment y by 1 and calculate PR.sub.2,3 through PR.sub.49,3 and
so forth until all coordinates between 2,2 and 49,49 have been
calculated and recorded.
[0482] These measurements and calculations are repeated in like
fashion at the same physical test sites using the diamond crystal
to tabulate a Diamond Results Grid.
[0483] Survey the Diamond Results Grid and identify the lowest
value for PR.sub.x,y. This value is PR.sub.Dia,min. Survey the
Germanium Results Grid and identify the lowest value for
PR.sub.x,y. This value is PR.sub.Ger,min. From these values,
calculate a Migration Coefficient (MC) for a non-activated region
as:
M .times. C non - activated = ( P .times. R Ge , min P .times. R
Dia , min - 1 ) 100 .times. % ##EQU00014##
Using PR.sub.Dia,min, calculate a MC for each value in the
Germanium Results Grid as:
M .times. C x , y = ( P .times. R Ge , x , y P .times. R Dia , min
- 1 ) 100 .times. % ##EQU00015##
to tabulate a MC Results Grid. To be identified as a heat activated
zone MC.sub.activated, a MC.sub.x,y must be at least 2.times. the
MC.sub.non-activated:
2MC.sub.non-activated.ltoreq.MC.sub.activated
Using this criteria, assign all coordinate sites in the physical
test grid as either Activated or Non-activated.
SEM Method for Determining Contact Angle on Fibers
[0484] A rectangular specimen measuring 1 cm.times.2 cm is cut from
the topsheet of a disposable absorbent product taking care not to
touch the surface of the specimen or to disturb the structure of
the material. The specimen shall be inclusive of any heat activated
zones identified via the Determination of Activated Zones by
FTIR/ATR test method described heretofore. To the extent that
additional heat activated zones lie outside of the specimen,
additional specimens shall be obtained to accommodate all of the
identified heat activated zones. The length of the specimen (2 cm)
is aligned with a longitudinal centerline of the article. The
specimen is handled gently by the edges using forceps and is
mounted flat with the skin-facing side up on an SEM specimen holder
using double-sided tape. The specimen is sprayed with a fine mist
of water droplets generated using a small hobby air-brush
apparatus. The water used to generate the droplets is distilled
deionized water with a resistivity of at least 18 M.OMEGA.-cm. The
airbrush is adjusted so that the droplets each have a volume of
about 2 pL. Approximately 0.5 mg of water droplets are evenly and
gently deposited onto the specimen. Immediately after applying the
water droplets, the mounted specimen is frozen by plunging it into
liquid nitrogen. After freezing, the sample is transferred to a
Cryo-SEM prep chamber at -150.degree. C., coated with Au/Pd, and
transferred into Cryo-SEM chamber at -150.degree. C. A Hitachi
S-4700 Cry-SEM or equivalent instrument is used to obtain
high-resolution images of the droplets on the fibers. Droplets are
randomly selected, though a droplet is suitable to be imaged only
if it is oriented in the microscope such that the projection of the
droplet extending from the fiber surface is approximately
maximized. This is further discussed with regard to FIGS. 31-34.
The contact angle between the droplet and the fiber is determined
directly from the images taken as is shown via lines 3700A, 3700B,
3800A, 3800B, 3900A, 3900B, 4000A, and 4000B. Twenty separate
droplets are imaged from which forty contact angle measurements are
performed (one on each side of each imaged droplet), and the
arithmetic average of these forty contact angle measurements is
calculated and reported as the contact angle for that specimen.
[0485] Examples of images are provided with regard to FIGS. 31-34.
FIGS. 31 and 32 are exemplary images depicting water droplets
cryogenically frozen on fibers upon which no composition has been
applied. FIGS. 33 and 34 are exemplary images depicting water
droplets cryogenically frozen on fibers upon which composition has
been applied. As noted previously, the projection of the droplet
should be maximized to ensure that the appropriate contact angle is
measured. An exemplary droplet projection 4100B is shown in FIG.
34B.
Method for Measuring the Pattern of the Zoned Activation
[0486] X-Ray Photoelectron Spectroscopy (XPS) and Time-of-Flight
Secondary Ion Mass Spectroscopy (TOF-SIMS) Imaging techniques are
very surface sensitive (penetration depth below 0.5 .mu.m) with a
lateral reslution of <10 .mu.m which can be used to visualize
the distribution of the melt additive on the surface of the polymer
after the activation.
[0487] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm."
[0488] Every document cited herein, including any cross referenced
or related patent or application, is hereby incorporated herein by
reference in its entirety unless expressly excluded or otherwise
limited. The citation of any document is not an admission that it
is prior art with respect to any invention disclosed or claimed
herein or that it alone, or in any combination with any other
reference or references, teaches, suggests or discloses any such
invention. Further, to the extent that any meaning or definition of
a term in this document conflicts with any meaning or definition of
the same term in a document incorporated by reference, the meaning
or definition assigned to that term in this document shall
govern.
[0489] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *