U.S. patent application number 14/844582 was filed with the patent office on 2016-03-17 for nonwoven material having discrete three-dimensional deformations with wide base openings that are tip bonded to additional layer.
The applicant listed for this patent is The Procter & Gamble Company. Invention is credited to Adrien Grenier, James Terry Knapmeyer, Jill Marlene Orr, Rodrigo Rosati, John Brian Strube.
Application Number | 20160074255 14/844582 |
Document ID | / |
Family ID | 54140721 |
Filed Date | 2016-03-17 |
United States Patent
Application |
20160074255 |
Kind Code |
A1 |
Strube; John Brian ; et
al. |
March 17, 2016 |
Nonwoven Material Having Discrete Three-Dimensional Deformations
With Wide Base Openings That are Tip Bonded to Additional Layer
Abstract
A composite sheet that includes a first sheet and a second sheet
is disclosed. The first and second sheets are bonded to each other
at a number of spaced apart discrete inter-sheet bond locations.
The first sheet is a nonwoven material that has discrete
three-dimensional deformations therein forming protrusions that
extend outward from the first surface of the first sheet to their
distal ends and wide base openings adjacent to the second surface
of the first sheet. The second sheet is a generally planar sheet
that contacts the distal ends of the protrusions on the first
sheet. The second sheet is bonded to the first sheet at spaced
apart inter-sheet bond locations where the distal ends of the
protrusions on the first sheet contact the second sheet.
Inventors: |
Strube; John Brian; (Okeana,
OH) ; Orr; Jill Marlene; (Liberty Township, OH)
; Knapmeyer; James Terry; (Cincinnati, OH) ;
Rosati; Rodrigo; (Frankfurt Am Main, DE) ; Grenier;
Adrien; (Frankfurt Am Main, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Procter & Gamble Company |
Cincinnati |
OH |
US |
|
|
Family ID: |
54140721 |
Appl. No.: |
14/844582 |
Filed: |
September 3, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62049376 |
Sep 12, 2014 |
|
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|
Current U.S.
Class: |
428/166 |
Current CPC
Class: |
D10B 2403/0111 20130101;
B32B 2262/12 20130101; B32B 2262/062 20130101; B32B 2307/726
20130101; D04H 13/001 20130101; B32B 3/30 20130101; B32B 2262/06
20130101; D04H 13/00 20130101; A61F 2013/51014 20130101; B32B 5/142
20130101; B32B 2555/02 20130101; A61F 13/5116 20130101; A61F
13/15699 20130101; B32B 5/22 20130101; B32B 2555/00 20130101; A61F
13/51104 20130101; A61F 13/51121 20130101; B32B 2262/14 20130101;
D10B 2509/02 20130101; B32B 2262/0261 20130101; B32B 5/06 20130101;
A61F 13/15577 20130101; A61F 13/51108 20130101; B32B 2262/02
20130101; A61F 13/51394 20130101; B32B 2262/0276 20130101; B32B
5/08 20130101; D04H 1/559 20130101; A61F 2013/51186 20130101; B32B
5/022 20130101; B32B 3/28 20130101; D04H 1/74 20130101; B32B
2262/0253 20130101; B32B 2262/04 20130101; A61F 2013/51007
20130101; B32B 5/26 20130101; B32B 2262/08 20130101 |
International
Class: |
A61F 13/511 20060101
A61F013/511; D04H 13/00 20060101 D04H013/00 |
Claims
1. A composite sheet comprising a first sheet and a second sheet
which are partially bonded to each other at a number of spaced
apart discrete inter-sheet bond locations, said composite sheet
comprising: a) a first sheet comprising a nonwoven web having a
first surface and a second surface comprising a generally planar
first region having a X-direction orientation, a Y-direction
orientation, and a plurality of discrete integral second regions
that comprise deformations, said deformations forming protrusions
extending outward from the first surface of said nonwoven web, and
openings formed in the second surface of the nonwoven web, said
protrusions being comprised of said fibers, wherein said
protrusions comprise a base proximate the first surface of said
nonwoven web, an opposed distal end extending outward in the
Z-direction from the base, and side walls between said base and
said distal end of said protrusion; and b) a generally planar
second sheet contacting the distal ends of the protrusions on said
first sheet, said second sheet being bonded to said first sheet at
a number of spaced apart discrete inter-sheet bond locations,
wherein said inter-sheet bond locations are disposed where the
distal ends of the protrusions on said first sheet contact the
second sheet, and said inter-sheet bond locations are spaced apart
in the X-direction and the Y-direction.
2. The composite sheet of claim 1 wherein said first sheet
comprises at least two layers and both layers have deformations
formed therein.
3. The composite sheet of claim 2 wherein at least one of said
layers is a spunbond nonwoven which has discrete bond sites
therein.
4. The composite sheet of claim 1 wherein said protrusions in said
first sheet have a bulbous configuration.
5. The composite sheet of claim 1 wherein the first region of the
first sheet has a first fiber concentration, the distal ends of the
protrusions have a second fiber concentration, and the side walls
of the protrusions have a third fiber concentration, wherein the
first fiber concentration is greater than the third fiber
concentration.
6. The composite sheet of claim 5 wherein at least the portion of
said first sheet at the distal ends of the protrusions that
contribute to form the inter-sheet bond locations which comprise
bonded portions of said protrusions, and said bonded portions of
said protrusions have fibers that are more densely packed than the
fibers in said first region.
7. The composite sheet of claim 6 wherein the fibers or portions of
fibers in said bonded portions of said protrusions are melted.
8. The composite sheet of claim 1 wherein the inter-sheet bond
locations comprise a majority of the distal ends of the
protrusions.
9. The composite sheet of claim 1 wherein the inter-sheet bond
locations comprise only a portion of the distal ends of the
protrusions.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to nonwoven materials
having discrete three-dimensional deformations with wide base
openings, methods of making the same, and articles including such
nonwoven materials.
BACKGROUND
[0002] Various materials for use in absorbent articles are
disclosed in the patent literature. Patent publications disclosing
such materials and methods for making the same include: U.S. Pat.
No. 4,323,068, Aziz; U.S. Pat. No. 5,518,801, Chappell, et al.;
U.S. Pat. No. 5,628,097, Benson, et al.; U.S. Pat. No. 5,804,021,
Abuto, et al.; U.S. Pat. No. 6,440,564 B1, McLain, et al.; U.S.
Pat. No. 7,172,801, Hoying, et al.; U.S. Pat. No. 7,410,683, Curro,
et al.; U.S. Pat. No. 7,553,532, Turner, et al.; U.S. Pat. No.
7,648,752 B2, Hoying, et al.; U.S. Pat. No. 7,682,686 B2, Curro, et
al.; U.S. Pat. No. 8,241,543 B2, O'Donnell, et al.; U.S. Pat. No.
8,393,374 B2, Sato, et al.; U.S. Pat. No. 8,585,958 B2, Gray, et
al.; U.S. Pat. No. 8,617,449 B2, Baker, et al.; U.S. Patent
Application Publications US 2006/0286343 A1; US 2010/0028621 A1; US
2010/0297377 A1; US 2012/0064298 A1; US 2013/0165883 A1; US
2014/0121621 A1; US 2014/0121623 A1; US 2014/0121624 A1; US
2014/0121625 A1; US 2014/0121626 A1; EP 1774940 B1; EP 1787611 B1;
EP 1982013 B1; PCT WO 2008/146594 A1; and WO 2014/084066 A1
(Zuiko). Kao MERRIES.TM. diapers and Kimberly-Clark HUGGIES.RTM.
diapers have premium products in which a textured topsheet is
bonded to another non-textured layer via heated embossing or
hydroentangling.
[0003] A need exists for improved materials for use in absorbent
articles, and methods of making such materials. In certain cases, a
need exists for improved nonwoven materials or laminates of
nonwoven materials that look and feel soft, and have improved
dryness. In particular, a need exists for improved nonwoven
materials having three-dimensional features formed therein to
provide improved softness and dryness, as well as a visual signal
of softness and dryness. The three dimensional features may form
depressions on one side of the material and protrusions on the
opposing side. In some cases, it may be desirable to place such
materials in an absorbent article so that the depressions are
visible on the topsheet of the absorbent article. In some of such
cases, it is desirable for such depressions to be well-defined and
have a wide opening formed thereby so that they may not only
improve liquid acquisition, but may also provide a "signal" to the
consumer of the liquid acquisition properties of an absorbent
article and ability to handle viscous fluids such as bowel
movements. It becomes increasingly more difficult to form
three-dimensional features that remain well-defined when making
such materials at high line speeds. In addition, in the event that
the material is incorporated into a product (such as a disposable
diaper) that is made or packaged under compression, it becomes
difficult to preserve the three-dimensional character of the
features/deformations after the material is subjected to such
compressive forces. Certain prior three dimensional structures have
a tendency to collapse or close and become much less visible after
compression. Further, a need exists for materials that can be
provided with such properties using mechanical deformation methods,
which are less costly than higher energy processes such as
hydroentangling and hydromolding.
[0004] Therefore, a need exists for such materials and high speed,
relatively inexpensive methods of making the same that have
deformations therein that provide well-defined three-dimensional
features, even after being compressed. A specific facet of high
speed is the compatibility with manufacturing lines for absorbent
articles, which offers the advantages of pattern flexibility and
zoning, and reduces the need to ship bulky materials.
SUMMARY
[0005] The present invention is directed to nonwoven materials
having discrete three-dimensional deformations with wide base
openings, methods of making the same, and articles including such
nonwoven materials.
[0006] The nonwoven materials have deformations formed therein. The
deformations form protrusions that extend outward from the first
surface of the nonwoven material and a base opening inside the
narrowest portion of the protrusion adjacent the second surface of
the nonwoven material. The protrusions may comprise a cap portion.
The maximum interior width of the cap portion of the protrusions
may be wider than the width of the base opening. The protrusions
may comprise fibers that extend from the base of the protrusion to
the distal end of the protrusions that contribute to form a portion
of the sides and cap of the protrusion. In some cases, multiple
such fibers may be disposed substantially completely around the
sides of the protrusions. In some cases, when compressive forces
are applied on the nonwoven web, at least some of the protrusions
may be configured to collapse in a controlled manner such that the
base opening may remain open. In some cases, the width of the
protrusions may vary along the length of the protrusions. In some
cases, the nonwoven material comprises at least two layers, and the
layers may differ in the concentration of fibers and/or the
presence of thermal point bonds at various locations in and around
the protrusions. In some cases, the deformations may have greater
light transmission than the adjacent undeformed regions. Any of the
properties described herein may be present in the nonwoven
materials separately, or in any combination.
[0007] The method of forming deformations in a nonwoven material
includes the steps of: a) providing at least one precursor nonwoven
web; b) providing a pair of forming members which include: a first
forming member having a surface comprising a plurality of discrete,
spaced apart male forming elements; and a second forming member
having a surface comprising a plurality of recesses in the second
forming member, wherein the recesses are each aligned and
configured to receive at least one of the male forming elements
therein, wherein the recesses may have a plan view periphery that
is larger than, and may completely surround, the plan view
periphery of the male elements; and c) placing the precursor
nonwoven web between the forming members and mechanically deforming
the precursor nonwoven web with the forming members. The method
forms a nonwoven web having a generally planar first region and a
plurality of discrete deformations. The deformations form
protrusions that extend outward from the first surface of the
nonwoven web and an opening in the second surface of the nonwoven
web.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a photomicrograph showing the end view of a prior
art tuft.
[0009] FIG. 2 is a schematic end view of a prior art tuft after it
has been subjected to compression.
[0010] FIG. 3 is a photomicrograph of the end of a prior art
nonwoven web showing a plurality of collapsed tufts.
[0011] FIG. 4 is a schematic side view of a prior art
conical-shaped structure before and after it has been subjected to
compression.
[0012] FIG. 5 is a plan view photomicrograph showing one side of
the nonwoven material having three-dimensional deformations formed
therein, with the protrusions oriented upward.
[0013] FIG. 6 is a plan view photomicrograph showing the other side
of a nonwoven material similar to that shown in FIG. 5, with the
openings in the nonwoven facing upward.
[0014] FIG. 7 is a Micro CT scan image showing a perspective view
of a protrusion in a single layer nonwoven material.
[0015] FIG. 8 is a Micro CT scan image showing a side of a
protrusion in a single layer nonwoven material.
[0016] FIG. 9 is a Micro CT scan image showing a perspective view
of a deformation with the opening facing upward in a single layer
nonwoven material.
[0017] FIG. 10 is a perspective view of a deformation in a two
layer nonwoven material with the opening facing upward.
[0018] FIG. 11 is a photomicrograph of a cross-section taken along
the transverse axis of a deformation showing one example of a
multi-layer nonwoven material having a three-dimensional
deformation in the form of a protrusion on one side of the material
that provides a wide opening on the other side of the material,
with the opening facing upward.
[0019] FIG. 12 is a schematic view of the protrusion shown in FIG.
11.
[0020] FIG. 13 is a plan view photomicrograph from the protrusion
side of a material after it has been subjected to compression
showing the high fiber concentration region around the perimeter of
the protrusion.
[0021] FIG. 14 is a photomicrograph of the cross-section of a
protrusion taken along the transverse axis of the protrusion
showing the protrusion after it has been subjected to
compression.
[0022] FIG. 15A is a cross-sectional view taken along the
transverse axis of a deformation of one embodiment of a multi-layer
nonwoven web shown with the base opening facing upward.
[0023] FIG. 15B is a cross-sectional view taken along the
transverse axis of a deformation of an alternative embodiment of a
multi-layer nonwoven web shown with the base opening facing
upward.
[0024] FIG. 15C is a cross-sectional view taken along the
transverse axis of a deformation of an alternative embodiment of a
multi-layer nonwoven web shown with the base opening facing
upward.
[0025] FIG. 15D is a cross-sectional view taken along the
transverse axis of a deformation of an alternative embodiment of a
multi-layer nonwoven web shown with the base opening facing
upward.
[0026] FIG. 15E is a cross-sectional view taken along the
transverse axis of a deformation of an alternative embodiment of a
multi-layer nonwoven web shown with the base opening facing
upward.
[0027] FIG. 15F is a cross-sectional view taken along the
transverse axis of a deformation of an alternative embodiment of a
multi-layer nonwoven web shown with the base opening facing
upward.
[0028] FIG. 16 is a plan view photomicrograph of a nonwoven web
with the protrusions oriented upward showing the concentration of
fibers in one layer of a two layer structure.
[0029] FIG. 17 is a perspective view photomicrograph showing the
reduced fiber concentration in the side walls of the protrusions in
a layer similar to that shown in FIG. 16.
[0030] FIG. 18 is a plan view photomicrograph of a nonwoven web
with the protrusions oriented upward showing the reduced
concentration of fibers in the cap of a protrusion in the other
layer (i.e. vs. the layer shown in FIG. 16) of a two layer
structure.
[0031] FIG. 19 is a perspective view photomicrograph showing the
decreased fiber concentration in the side walls of the protrusions
in a layer similar to that shown in FIG. 18.
[0032] FIG. 19A is a Micro CT scan image showing the side of a
protrusion in a single layer of nonwoven material with the
protrusion oriented downward.
[0033] FIG. 19B is a Micro CT scan plan view image showing the base
opening of a deformation in a single layer of nonwoven
material.
[0034] FIG. 20 is a perspective view photomicrograph of one layer
of a multiple layer nonwoven material on the surface of a forming
roll showing the "hanging chads" that can be formed in one of the
layers when some nonwoven precursor web materials are used.
[0035] FIG. 21 is a perspective view of one example of an apparatus
for forming the nonwoven material described herein.
[0036] FIG. 22 is an enlarged perspective view of a portion of the
male roll shown in FIG. 21.
[0037] FIG. 22A is an enlarged schematic side view showing an
example of a surface texture formed by knurling a forming
member.
[0038] FIG. 22A is a schematic side view of a male element with
tapered side walls.
[0039] FIG. 22B is a schematic side view of a male element with
undercut side walls.
[0040] FIG. 22C is an enlarged perspective view of a portion of a
male roll having an alternative configuration.
[0041] FIG. 22D is a schematic side view of a male element with a
rounded top.
[0042] FIG. 22E is a magnified photograph of the top surface of a
male element that has been roughened by sandblasting.
[0043] FIG. 22F is a magnified photograph of the top surface of a
male element that has a relatively smooth surface formed by
machining the same.
[0044] FIG. 22G is a schematic side view showing an example of
macro texture and micro texture that can be created by knurling the
surface of a male or female forming member.
[0045] FIG. 23 is an enlarged perspective view showing the nip
between the rolls shown in FIG. 21.
[0046] FIG. 23A is a schematic side view of a recess in a female
forming member with a rounded top edge or rim.
[0047] FIG. 23B is a photograph of a second forming member having a
surface that has been roughened with diamond type knurling.
[0048] FIG. 24 is a schematic perspective view of one version of a
method of making nonwoven materials having deformations therein
where two precursor materials are used, one of which is a
continuous web and the other of which is in the form of discrete
pieces.
[0049] FIG. 24A is a schematic side view of an apparatus for
forming the nonwoven material in which the web wraps around one of
the rolls before and after passing through the nip between the
rolls.
[0050] FIG. 25 is an absorbent article in the form of a diaper
comprising an exemplary topsheet/acquisition layer composite
structure wherein the length of the acquisition layer is less that
the length of the topsheet with some layers partially removed.
[0051] FIG. 26 is one transverse cross-section of the diaper of
FIG. 25 taken along line 26-26.
[0052] FIG. 27 is an alternative transverse cross-section of the
diaper of FIG. 25.
[0053] FIG. 28 is a schematic side view of an apparatus for forming
the nonwoven material which includes an additional roll for tip
bonding the layers of a multiple layer nonwoven material.
[0054] FIG. 29 is a schematic cross-sectional view of a tip bonded
protrusion (shown oriented downward) made by the apparatus shown in
FIG. 28.
[0055] FIG. 30 is a schematic side view of an apparatus for tip
bonding the deformed nonwoven material to an additional layer.
[0056] FIG. 31 is a schematic perspective view of a portion of a
deformed nonwoven web protrusion tip bonded to an additional layer
(only a portion of the additional layer is shown) made by the
apparatus shown in FIG. 30.
[0057] FIG. 32 is a schematic side view of an apparatus for
deforming the nonwoven material which includes an additional roll
for base bonding the deformed nonwoven material.
[0058] FIG. 33A is a plan view of a_base bonded nonwoven made by
the apparatus shown in FIG. 32 (shown with the base opening
oriented upward).
[0059] FIG. 33B is a schematic cross-sectional view of the base
bonded nonwoven shown in FIG. 33A taken along line 33B-33B.
[0060] FIG. 34 is a plan view photomicrograph showing the bonds
formed by the apparatus shown in FIG. 32.
[0061] FIG. 35 is a schematic side view of an apparatus for base
bonding the deformed nonwoven material to an additional layer.
[0062] FIG. 35A is an enlarged perspective view of a portion of one
embodiment of a female roll having a plurality of discrete bonding
elements on its surface.
[0063] FIG. 35B is an enlarged perspective view of a portion of one
embodiment of a female roll having continuous bonding elements on
its surface.
[0064] FIG. 35C is a plan view of a portion of the surface of one
embodiment of a bonding roll with a plurality of discrete bonding
elements thereon.
[0065] FIG. 36 is a schematic perspective view of a portion of a
deformed nonwoven web that is base bonded to an additional layer
(only a portion of the additional layer is shown) made by the
apparatus shown in FIG. 35.
[0066] FIG. 37 is a plan view photograph of a nonwoven material as
described herein with the base openings oriented upward.
[0067] FIG. 38 is a plan view photograph of an apertured nonwoven
material.
[0068] FIG. 39 is a plan view photograph of a currently marketed
topsheet.
[0069] FIG. 40 is a schematic side view of an apparatus for
deforming the nonwoven material which includes additional rolls for
tip bonding and base bonding the deformed nonwoven material.
[0070] FIG. 41 is a schematic side view of an apparatus for
deforming the nonwoven material which includes additional rolls for
tip bonding the deformed nonwoven material and then base bonding
the deformed nonwoven material to an additional layer.
[0071] FIG. 42 is a schematic side view of an apparatus for
deforming the nonwoven material which includes additional rolls for
base bonding the deformed nonwoven material and then tip bonding
the deformed nonwoven material_to an additional layer.
[0072] The embodiment(s) of the nonwoven material, the articles,
the method and the apparatus(es) shown in the drawings are
illustrative in nature and are not intended to be limiting of the
invention defined by the claims. Moreover, the features of the
invention will be more fully apparent and understood in view of the
detailed description.
DETAILED DESCRIPTION
I. Definitions
[0073] The term "absorbent article" includes disposable articles
such as sanitary napkins, panty liners, tampons, interlabial
devices, wound dressings, diapers, adult incontinence articles,
wipes, and the like. At least some of such absorbent articles are
intended for the absorption of body liquids, such as menses or
blood, vaginal discharges, urine, and feces. Wipes may be used to
absorb body liquids, or may be used for other purposes, such as for
cleaning surfaces. Various absorbent articles described above will
typically comprise a liquid pervious topsheet, a liquid impervious
backsheet joined to the topsheet, and an absorbent core between the
topsheet and backsheet. The nonwoven material described herein can
comprise at least part of other articles such as scouring pads, wet
or dry-mop pads (such as SWIFFER.RTM. pads), and the like.
[0074] The term "absorbent core", as used herein, refers to the
component of the absorbent article that is primarily responsible
for storing liquids. As such, the absorbent core typically does not
include the topsheet or backsheet of the absorbent article.
[0075] The term "aperture", as used herein, refers to a regular or
substantially regularly-shaped hole that is intentionally formed
and extends completely through a web or structure (that is, a
through hole). The apertures can either be punched cleanly through
the web so that the material surrounding the aperture lies in the
same plane as the web prior to the formation of the aperture (a
"two dimensional" aperture), or the holes can be formed such that
at least some of the material surrounding the opening is pushed out
of the plane of the web. In the latter case, the apertures may
resemble a depression with an aperture therein, and may be referred
to herein as a "three dimensional" aperture, a subset of
apertures.
[0076] The term "component" of an absorbent article, as used
herein, refers to an individual constituent of an absorbent
article, such as a topsheet, acquisition layer, liquid handling
layer, absorbent core or layers of absorbent cores, backsheets, and
barriers such as barrier layers and barrier cuffs.
[0077] The term "cross-machine direction" or "CD" means the path
that is perpendicular to the machine direction in the plane of the
web.
[0078] The term "deformable material", as used herein, is a
material which is capable of changing its shape or density in
response to applied stresses or strains.
[0079] The term "discrete", as used herein, means distinct or
unconnected. When the term "discrete" is used relative to forming
elements on a forming member, it is meant that the distal (or
radially outwardmost) ends of the forming elements are distinct or
unconnected in all directions, including in the machine and
cross-machine directions (even though bases of the forming elements
may be formed into the same surface of a roll, for example).
[0080] The term "disposable" is used herein to describe absorbent
articles and other products which are not intended to be laundered
or otherwise restored or reused as an absorbent article or product
(i.e., they are intended to be discarded after use and, preferably,
to be recycled, composted or otherwise disposed of in an
environmentally compatible manner).
[0081] The term "forming elements", as used herein, refers to any
elements on the surface of a forming member that are capable of
deforming a web.
[0082] The term "integral", as used herein as in "integral
extension" when used to describe the protrusions, refers to fibers
of the protrusions having originated from the fibers of the
precursor web(s). Thus, as used herein, "integral" is to be
distinguished from fibers introduced to or added to a separate
precursor web for the purpose of making the protrusions.
[0083] The term "joined to" encompasses configurations in which an
element is directly secured to another element by affixing the
element directly to the other element; configurations in which the
element is indirectly secured to the other element by affixing the
element to intermediate member(s) which in turn are affixed to the
other element; and configurations in which one element is integral
with another element, i.e., one element is essentially part of the
other element. The term "joined to" encompasses configurations in
which an element is secured to another element at selected
locations, as well as configurations in which an element is
completely secured to another element across the entire surface of
one of the elements. The term "joined to" includes any known manner
in which elements can be secured including, but not limited to
mechanical entanglement.
[0084] The term "machine direction" or "MD" means the path that
material, such as a web, follows through a manufacturing
process.
[0085] The term "macroscopic", as used herein, refers to structural
features or elements that are readily visible and distinctly
discernable to a human having 20/20 vision when the perpendicular
distance between the viewer's eye and the web is about 12 inches
(30 cm). Conversely, the term "microscopic" refers to such features
that are not readily visible and distinctly discernable under such
conditions.
[0086] The term "mechanically deforming", as used herein, refers to
processes in which a mechanical force is exerted upon a material in
order to permanently deform the material.
[0087] The term "permanently deformed", as used herein, refers to
the state of a deformable material whose shape or density has been
permanently altered in response to applied stresses or strains.
[0088] The terms "SELF" and "SELF'ing", refer to Procter &
Gamble technology in which SELF stands for Structural Elastic Like
Film. While the process was originally developed for deforming
polymer film to have beneficial structural characteristics, it has
been found that the SELF'ing process can be used to produce
beneficial structures in other materials. Processes, apparatuses,
and patterns produced via SELF are illustrated and described in
U.S. Pat. Nos. 5,518,801; 5,691,035; 5,723,087; 5,891,544;
5,916,663; 6,027,483; and 7,527,615 B2.
[0089] The term "tuft", as used herein, refers to a particular type
of feature that may be formed from fibers in a nonwoven web. Tufts
may have a tunnel-like configuration which may be open at both of
their ends.
[0090] The term "web" is used herein to refer to a material whose
primary dimension is X-Y, i.e., along its length (or longitudinal
direction) and width (or transverse direction). It should be
understood that the term "web" is not necessarily limited to single
layers or sheets of material. Thus the web can comprise laminates
or combinations of several sheets of the requisite type of
materials.
[0091] The term "Z-dimension" refers to the dimension orthogonal to
the length and width of the web or article. The Z-dimension usually
corresponds to the thickness of the web or material. As used
herein, the term "X-Y dimension" refers to the plane orthogonal to
the thickness of the web or material. The X-Y dimension usually
corresponds to the length and width, respectively, of the web or
material.
II. Nonwoven Materials
[0092] The present invention is directed to nonwoven materials
having discrete three-dimensional deformations, which deformations
provide protrusions on one side of the material, and openings on
the other side of the nonwoven materials. Methods of making the
nonwoven materials are also disclosed. The nonwoven materials can
be used in absorbent articles and other articles.
[0093] As used herein, the term "nonwoven" refers to a web or
material having a structure of individual fibers or threads which
are interlaid, but not in a repeating pattern as in a woven or
knitted fabric, which latter types of fabrics do not typically have
randomly oriented or substantially randomly-oriented fibers.
Nonwoven webs will have a machine direction (MD) and a cross
machine direction (CD) as is commonly known in the art of web
manufacture. By "substantially randomly oriented" is meant that,
due to processing conditions of the precursor web, there may be a
higher amount of fibers oriented in the MD than the CD, or vice
versa. For example, in spunbonding and meltblowing processes
continuous strands of fibers are deposited on a support moving in
the MD. Despite attempts to make the orientation of the fibers of
the spunbond or meltblown nonwoven web truly "random," usually a
slightly higher percentage of fibers are oriented in the MD as
opposed to the CD.
[0094] Nonwoven webs and materials are often incorporated into
products, such as absorbent articles, at high manufacturing line
speeds. Such manufacturing processes can apply compressive and
shear forces on the nonwoven webs that may damage certain types of
three-dimensional features that have been purposefully formed in
such webs. In addition, in the event that the nonwoven material is
incorporated into a product (such as a disposable diaper) that is
made or packaged under compression, it becomes difficult to
preserve the three-dimensional character of some types of prior
three-dimensional features after the material is subjected to such
compressive forces.
[0095] For instance, FIGS. 1 and 2 show an example of a prior art
nonwoven material 10 with a tufted structure. The nonwoven material
comprises tufts 12 formed from looped fibers 14 that form a
tunnel-like structure having two ends 16. The tufts 12 extend
outward from the plane of the nonwoven material in the Z-direction.
The tunnel-like structure has a width that is substantially the
same from one end of the tuft to the opposing end. Often, such
tufted structures will have holes or openings 18 at both ends and
an opening 20 at their base. Typically, the openings 18 at the ends
of the tufts are at the machine direction (MD) ends of the tufts.
The openings 18 at the ends of the tufts can be a result of the
process used to form the tufts. If the tufts 12 are formed by
forming elements in the form of teeth with a relatively small tip
and vertical leading and trailing edges that form a sharp point,
these leading and/or trailing edges may punch through the nonwoven
web at least one of the ends of the tufts. As a result, openings 18
may be formed at one or both ends of the tufts 12.
[0096] While such a nonwoven material 10 provides well-defined
tufts 12, the opening 20 at the base of the tuft structure can be
relatively narrow and difficult to see with the naked eye. In
addition, as shown in FIG. 2, the material of the tuft 12
surrounding this narrow base opening 20 may tend to form a hinge
22, or pivot point if forces are exerted on the tuft. If the
nonwoven is compressed (such as in the Z-direction), in many cases,
the tufts 12 can collapse to one side and close off the opening 20.
Typically, a majority of the tufts in such a tufted material will
collapse and close off the openings 20. FIG. 2 schematically shows
an example of a tuft 12 after it has collapsed. In FIG. 2, the tuft
12 has folded over to the left side. FIG. 3 is an image showing a
nonwoven material with several upwardly-oriented tufts, all of
which have folded over to the side. However, not all of the tufts
12 will collapse and fold over to the same side. Often, some tufts
12 will fold to one side, and some tufts will fold to the other
side. As a result of the collapse of the tufts 12, the openings 20
at the base of the tufts can close up, become slit-like, and
virtually disappear.
[0097] Prior art nonwoven materials with certain other types of
three dimensional deformations, such as conical structures, can
also be subject to collapse when compressed. As shown in FIG. 4,
conical structures 24 will not necessarily fold over as will
certain tufted structures when subjected to compressive forces F.
However, conical structures 24 can be subject to collapse in that
their relatively wide base opening 26 and smaller tip 28 causes the
conical structure to push back toward the plane of the nonwoven
material, such as to the configuration designated 24A.
[0098] The nonwoven materials of at least some embodiments of the
present invention described herein are intended to better preserve
the structure of discrete three-dimensional features in the
nonwoven materials after compression.
[0099] FIGS. 5-14 show examples of nonwoven materials 30 with
three-dimensional deformations comprising protrusions 32 therein.
The nonwoven materials 30 have a first surface 34, a second surface
36, and a thickness T therebetween (the thickness being shown in
FIG. 12). FIG. 5 shows the first surface 34 of a nonwoven material
30 with the protrusions 32 that extend outward from the first
surface 34 of the nonwoven material oriented upward. FIG. 6 shows
the second surface 36 of a nonwoven material 30 such as that shown
in FIG. 5, having three-dimensional deformations formed therein,
with the protrusions oriented downward and the base openings 44
oriented upward. FIG. 7 is a Micro CT scan image showing a
perspective view of a protrusion 32. FIG. 8 is a Micro CT scan
image showing a side view of a protrusion 32 (of one of the longer
sides of the protrusion). FIG. 9 is a Micro CT scan image showing a
perspective view of a deformation with the opening 44 facing
upward. The nonwoven materials 30 comprise a plurality of fibers 38
(shown in FIGS. 7-11 and 14). As shown in FIGS. 7 and 9, in some
cases, the nonwoven material 30 may have a plurality of bonds 46
(such as thermal point bonds) therein to hold the fibers 38
together. Any such bonds 46 are typically present in the precursor
material from which the nonwoven materials 30 are formed.
[0100] The protrusions 32 may, in some cases, be formed from looped
fibers (which may be continuous) 38 that are pushed outward so that
they extend out of the plane of the nonwoven web in the
Z-direction. The protrusions 32 will typically comprise more than
one looped fiber. In some cases, the protrusions 32 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 protrusions
32 may be formed from loops comprising multiple discontinuous
fibers. Multiple discontinuous fibers in the form of a loop are
shown as layer 30A in FIGS. 15A-15F. 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.
[0101] In some cases, if male/female forming elements are used to
form the protrusions 32, and the female forming elements
substantially surround the male forming elements, the fibers in at
least part of the protrusions 32 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 protrusions, but
be more aligned in the side walls such that the fibers extend in
the Z-direction 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 protrusion 32
within the same layer.
[0102] The nonwoven material 30 may comprise a generally planar
first region 40 and the three-dimensional deformations may comprise
a plurality of discrete integral second regions 42. The term
"generally planar" is not meant to imply any particular flatness,
smoothness, or dimensionality. Thus, the first region 40 can
include other features that provide the first region 40 with a
topography. Such other features can include, but are not limited to
small projections, raised network regions around the base openings
44, and other types of features. Thus, the first region 40 is
generally planar when considered relative to the second regions 42.
The first region 40 can have any suitable plan view configuration.
In some cases, the first region 40 is in the form of a continuous
inter-connected network which comprises portions that surround each
of the deformations.
[0103] The term "deformation", as used herein, includes both the
protrusions 32 formed on one side of the nonwoven material and the
base openings 44 formed in the opposing side of the material. The
base openings 44 are most often not in the form of an aperture or a
through-hole. The base openings 44 may instead appear as
depressions. The base openings 44 can be analogized to the opening
of a bag. A bag has an opening that typically does not pass
completely through the bag. In the case of the present nonwoven
materials 30, as shown in FIG. 10, the base openings 44 open into
the interior of the protrusions 32.
[0104] FIG. 11 shows one example of a multi-layer nonwoven material
30 having a three-dimensional deformation in the form of a
protrusion 32 on one side of the material that provides a wide base
opening 44 on the other side of the material. The dimensions of
"wide" base openings are described in further detail below. In this
case, the base opening 44 is oriented upward in the figure. When
there is more than one nonwoven layer, the individual layers can be
designated 30A, 30B, etc. The individual layers 30A and 30B each
have first and second surfaces, which can be designated similarly
to the first and second surfaces 34 and 36 of the nonwoven material
(e.g., 34A and 36A for the first and second surfaces of the first
layer 30A; and, 34B and 36B for the first and second surfaces of
the second layer 30B).
[0105] As shown in FIGS. 11 and 12, the protrusions 32 comprise: a
base 50 proximate the first surface 34 of the nonwoven material; an
opposed enlarged distal portion or cap portion, or "cap" 52, that
extends to a distal end 54; side walls (or "sides") 56; an interior
58; and a pair of ends 60 (the latter being shown in FIG. 5). The
"base" 50 of the protrusions 32 comprises the narrowest portion of
the protrusion when viewed from one of the ends of the protrusion.
The term "cap" does not imply any particular shape, other than it
comprises the wider portion of the protrusion 32 that includes and
is adjacent to the distal end 54 of the protrusion 32. The side
walls 56 have an inside surface 56A and an outside surface 56B. As
shown in FIGS. 11 and 12, the side walls 56 transition into, and
may comprise part of the cap 52. Therefore, it is not necessary to
precisely define where the side walls 56 end and the cap 52 begins.
The cap 52 will have a maximum interior width, W.sub.I, between the
inside surfaces 56A of the opposing side walls 56. The cap 52 will
also have a maximum exterior width W between the outside surfaces
56B of the opposing side walls 56. The ends 60 of the protrusions
32 are the portions of the protrusions that are spaced furthest
apart along the longitudinal axis, L, of the protrusions.
[0106] As shown in FIGS. 11 and 12, the narrowest portion of the
protrusion 32 defines the base opening 44. The base opening 44 has
a width W.sub.O. The base opening 44 may be located (in the
z-direction) between the plane defined by the second surface 36 of
the material and the distal end 54 of the protrusion. As shown in
FIGS. 11 and 12, the nonwoven material 30 may have an opening in
the second surface 36 (the "second surface opening" 64) that
transitions into the base opening 44 (and vice versa), and is the
same size as, or larger than the base opening 44. The base opening
44 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 nonwoven material 30 is placed in an
article with the base openings 44 visible to the consumer. It
should be understood that in certain embodiments, such as in some
embodiments in which the base openings 44 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 44
not to be covered and/or closed off by another web.
[0107] As shown in FIG. 12, the protrusions 32 have a depth D
measured from the second surface 36 of the nonwoven web to the
interior of the protrusion at the distal end 54 of the protrusions.
The protrusions 32 have a height H measured from the second surface
36 of the nonwoven web to the distal end 54 of the protrusions. In
most cases the height H of the protrusions 32 will be greater than
the thickness T of the first region 40. The relationship between
the various portions of the deformations may be such that as shown
in FIG. 11, when viewed from the end, the maximum interior width
W.sub.I of the cap 52 of the protrusions is wider than the width,
W.sub.O, of the base opening 44.
[0108] The protrusions 32 may be of any suitable shape. Since the
protrusions 32 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. 5, 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 44 will typically have a shape similar to the plan view
shape of the protrusions 32.) In other cases, the protrusions 32
(and base openings 44) may be non-circular. The protrusions 32 may
have similar plan view dimensions in all directions, or the
protrusions may be longer in one dimension than another. That is,
the protrusions 32 may have different length and width dimensions.
If the protrusions 32 have a different length than width, the
longer dimension will be referred to as the length of the
protrusions. The protrusions 32 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.
[0109] As shown in FIG. 5, the protrusions 32 may have a width, W,
that varies from one end 60 to the opposing end 60 when the
protrusions are viewed in plan view. The width W may vary with the
widest portion of the protrusions in the middle of the protrusions,
and the width of the protrusions decreasing at the ends 60 of the
protrusions. In other cases, the protrusions 32 could be wider at
one or both ends 60 than in the middle of the protrusions. In still
other cases, protrusions 32 can be formed that have substantially
the same width from one end of the protrusion to the other end of
the protrusion. If the width of the protrusions 32 varies along the
length of the protrusions, the portion of the protrusion where the
width is the greatest is used in determining the aspect ratio of
the protrusions.
[0110] When the protrusions 32 have a length L that is greater than
their width W, the length of the protrusions may be oriented in any
suitable direction relative to the nonwoven material 30. For
example, the length of the protrusions 32 (that is, the
longitudinal axis, LA, of the protrusions) may be oriented in the
machine direction, the cross-machine direction, or any desired
orientation between the machine direction and the cross-machine
direction. The protrusions 32 also have a transverse axis TA
generally orthogonal to the longitudinal axis LA in the MD-CD
plane. In the embodiment shown in FIGS. 5 and 6, the longitudinal
axis LA is parallel to the MD. In some embodiments, all the spaced
apart protrusions 32 may have generally parallel longitudinal axes
LA.
[0111] The protrusions 32 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 protrusions 32 may, but need not, have a
mushroom-like stem portion.) In some cases, the protrusions 32 may
be referred to as having a bulbous shape when viewed from the end
60, such as in FIG. 11. The term "bulbous", as used herein, is
intended to refer to the configuration of the protrusions 32 as
having a cap 52 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 60) of the protrusion 32. The
term "bulbous" is not limited to protrusions that have a circular
or round plan view configuration that is joined to a columnar
portion. The bulbous shape, in the embodiment shown (where the
longitudinal axis LA of the deformations 32 is oriented in the
machine direction), may be most apparent if a section is taken
along the transverse axis TA of the deformation (that is, in the
cross-machine direction). The bulbous shape may be less apparent if
the deformation is viewed along the length (or longitudinal axis
LA) of the deformation such as in FIG. 8.
[0112] The protrusions 32 may comprise fibers 38 that at least
substantially surround the sides of the protrusions. This means
that there are multiple fibers that extend (e.g., in the
Z-direction) from the base 50 of the protrusions 32 to the distal
end 54 of the protrusions, and contribute to form a portion of the
sides 56 and cap 52 of a protrusion. In some cases, the fibers may
be substantially aligned with each other in the Z-direction in the
sides 56 of the protrusions 32. 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 protrusions. If the fibers 38 are located completely
around the sides of the protrusions, this would mean that the
fibers are located 360.degree. around the protrusions. The
protrusions 32 may be free of large openings at their ends 60, such
as those openings 18 at the leading end and trailing end of the
tufts shown in FIG. 1. In some cases, the protrusions 32 may have
an opening at only one of their ends, such as at their trailing
end. The protrusions 32 also differ from embossed structures such
as shown in FIG. 4. Embossed structures typically do not have
distal portions that are spaced perpendicularly away (that is, in
the Z-direction) from their base that are wider than portions that
are adjacent to their base, as in the case of the cap 52 on the
present protrusions 32.
[0113] The protrusions 32 may have certain additional
characteristics. As shown in FIGS. 11 and 12, the protrusions 32
may be substantially hollow. As used herein, the term
"substantially hollow" refers to structures which the protrusions
32 are substantially free of fibers in interior of protrusions. The
term "substantially hollow", does not, however, require that the
interior of the protrusions must be completely free of fibers.
Thus, there can be some fibers inside the protrusions.
"Substantially hollow" protrusions 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.
[0114] The side walls 56 of the protrusions 32 can have any
suitable configuration. The configuration of the side walls 56,
when viewed from the end of the protrusion such as in FIG. 11, can
be linear or curvilinear, or the side walls 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 side walls 56 in the embodiment shown in FIG. 11
comprise portions that are curvilinear concave inwardly near the
base of the protrusions and convex outwardly near the cap of the
protrusions. The sidewalls 56 and the area around the base opening
44 of the protrusions may, under 20.times. magnification, have a
visibly 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 nonwoven in the unformed first region 40.
The protrusions 32 may also have thinned fibers in the sidewalls
56. The fiber thinning, if present, will be apparent in the form of
necked regions in the fibers 38 as seen in scanning electron
microscope (SEM) images taken at 200.times. magnification. Thus,
the fibers may have a first cross-sectional area when they are in
the undeformed nonwoven precursor web, and a second cross-sectional
area in the side walls 56 of the protrusions 32 of the deformed
nonwoven web, wherein the first cross-sectional area is greater
than the second cross-sectional area. The side walls 56 may also
comprise some broken fibers as well. In some embodiments, the side
walls 56 may comprise greater than or equal to about 30%,
alternatively greater than or equal to about 50% broken fibers.
[0115] In some embodiments, the distal end 54 of the protrusions 32
may be comprised of original basis weight, non-thinned, and
non-broken fibers. If the base opening 44 faces upward, the distal
end 54 will be at the bottom of the depression that is formed by
the protrusion. The distal end 54 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) such as shown
in FIGS. 15D-15F and FIG. 20 resulting from localized tearing of
the material(s) during the process of forming deformations therein,
which breaks may be due to variability in the precursor
material(s). The distal end 54 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. As described in greater detail
below, however, if the nonwoven web is comprised of more than one
layer, the concentration of fibers in the different portions of the
protrusions may vary between the different layers.
[0116] The protrusions 32 may be of any suitable size. The size of
the protrusions 32 can be described in terms of protrusion length,
width, caliper, height, depth, cap size, and opening size. (Unless
otherwise stated, the length L and width W of the protrusions are
the exterior length and width of the cap 52 of the protrusions.)
The dimensions of the protrusions and openings can be measured
before and after compression (under either a pressure of 7 kPa or
35 KPa, whichever is specified) in accordance with the Accelerated
Compression Method described in the Test Methods section. The
protrusions have a caliper that is measured between the same points
as the height H, but under a 2 KPa load, in accordance with the
Accelerated Compression Method. All dimensions of the protrusions
and openings other than caliper (that is, length, width, height,
depth, cap size, and opening size) are measured without pressure
applied at the time of making the measurement using a microscope at
20.times. magnification.
[0117] In some embodiments, the length of the cap 52 may be in a
range from about 1.5 mm to about 10 mm. In some embodiments, 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.
[0118] The nonwoven material 30 can comprise a composite of two or
more nonwoven materials that are joined together. In such a case,
the fibers and properties of the first layer will be designated
accordingly (e.g., the first layer is comprised of a first
plurality of fibers), and the fibers and properties of the second
and subsequent layers will be designated accordingly (e.g., the
second layer is comprised of a second plurality of fibers). In a
two or more layer structure, there are a number of possible
configurations the layers may take following the formation of the
deformations therein. These will often depend on the extensibility
of the nonwoven materials used for the layers. It is desirable that
at least one of the layers have deformations which form protrusions
32 as described herein in which, along at least one cross-section,
the width of the cap 52 of the protrusions is greater than the
width of the base opening 44 of the deformations. For example, in a
two layer structure where one of the layers will serve as the
topsheet of an absorbent article and the other layer will serve as
an underlying layer (such as an acquisition layer), the layer that
has protrusions therein may comprise the topsheet layer. The layer
that most typically has a bulbous shape will be the one which is in
contact with the male forming member during the process of
deforming the web. FIG. 15A-FIG. 15E show different alternative
embodiments of three-dimensional protrusions 32 in multiple layer
materials.
[0119] In certain embodiments, such as shown in FIGS. 11, 12, and
15A, similar-shaped looped fibers may be formed in each layer of
multiple layer nonwoven materials, including in the layer 30A that
is spaced furthest from the discrete male forming elements during
the process of forming the protrusions 32 therein, and in the layer
30B that is closest to the male forming elements during the
process. In the protrusions 32, portions of one layer such as 30B
may fit within the other layer, such as 30A. These layers may be
referred to as forming a "nested" structure in the protrusions 32.
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.
[0120] As shown in FIG. 15A, a three-dimensional protrusion 32
comprises protrusions 32A formed in the first layer 30A and
protrusions 32B formed in the second layer 30B. In one embodiment,
the first layer 30A may be incorporated into an absorbent article
as an acquisition layer, and the second layer 30B may be a
topsheet, and the protrusions formed by the two layers may fit
together (that is, are nested). In this embodiment, the protrusions
32A and 32B formed by the first and second layers 30A and 30B fit
closely together. The three-dimensional protrusion 32A comprises a
plurality of fibers 38A and the three-dimensional protrusion 32B
comprises a plurality of fibers 38B. The three-dimensional
protrusion 32B is nested into the three-dimensional protrusion 32A.
In the embodiment shown, the fibers 38A in the first layer 30A are
shorter in length than the fibers 38B in the second layer 30B. In
other embodiments, 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. In
addition, in this embodiment, and any of the other embodiments
described herein, the nonwoven layers can be inverted when
incorporated into an absorbent article, or other article, so that
the protrusions 32 face upward (or outward). In such a case, the
material suitable for the topsheet will be used in layer 30A, and
material suitable for the underlying layer will be used in layer
30B.
[0121] FIG. 15B shows that the nonwoven layers need not be in a
contacting relationship within the entirety of the protrusion 32.
Thus, the protrusions 32A and 32B formed by the first and second
layers 30A and 30B may have different heights and/or widths. The
two materials may have substantially the same shape in the
protrusion 32 as shown in FIG. 15B (where one of the materials has
the same the curvature as the other). In other embodiments,
however, the layers may have different shapes. It should be
understood that FIG. 15B 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.
[0122] As shown in FIG. 15C, one of the layers, such as first layer
30A (e.g., an acquisition layer) may be ruptured in the area of the
three-dimensional protrusion 32. As shown in FIG. 15C, the
protrusions 32 are only formed in the second layer 30B (e.g., the
topsheet) and extend through openings in the first layer 30A. That
is, the three-dimensional protrusion 32B in the second layer 30B
interpenetrates the ruptured first layer 30A. 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 an embodiment, the layers are not considered to be "nested" in
the area of the protrusion. (In the other embodiments shown in
FIGS. 15D-15F, the layers would still be considered to be
"nested".) Such a structure may be formed if the material of the
second layer 30B is much more extensible than the material of the
first layer 30A. In such a case, the openings can be formed by
locally rupturing first precursor web by the process described in
detail below. The ruptured layer may have any suitable
configuration in the area of the protrusion 32. Rupture may involve
a simple splitting open of first precursor web, such that the
opening in the first layer 30A remains a simple two-dimensional
aperture. However, for some materials, portions of the first layer
30A can be deflected or urged out-of-plane (i.e., out of the plane
of the first layer 30A) to form flaps 70. The form and structure of
any flaps is highly dependent upon the material properties of the
first layer 30A. Flaps can have the general structure shown in FIG.
15C. In other embodiments, the flaps 70 can have a more
volcano-like structure, as if the protrusion 32B is erupting from
the flaps.
[0123] Alternatively, as shown in FIGS. 15D-15F, one or both of the
first layer 30A and the second layer 30B may be interrupted (or
have a break therein) in the area of the three-dimensional
protrusion 32. FIGS. 15D and 15E show that the three-dimensional
protrusion 32A of the first layer 30A may have an interruption 72A
therein. The three-dimensional protrusion 32B of the
non-interrupted second layer 30B may coincide with and fit together
with the three-dimensional protrusion 32A of the interrupted first
layer 30A. Alternatively, FIG. 15F shows an embodiment in which
both the first and second layers 30A and 30B have interruptions, or
breaks, therein (72A and 72B, respectively). In this case, the
interruptions in the layers 30A and 30B are in different locations
in the protrusion 32. FIGS. 15D-15F 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 54 of
the protrusions 32.
[0124] For dual layer and other multiple layer structures, the
basis weight distribution (or the concentration of fibers) within
the deformed material 30, as well as the distribution of any
thermal point bonds 46 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 46, 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.
[0125] 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.
[0126] In such dual and multiple layer nonwoven materials each of
the layers comprises a plurality of fibers, and in certain
embodiments, the protrusions 32 will be formed from fibers in each
of the layers. For example, one of the layers, a first layer, may
form the first surface 34 of the nonwoven material 30, and one of
the layers, a second layer, may form the second surface 36 of the
nonwoven material 30. A portion of the fibers in the first layer
form part of: the first region 40, the side walls 56 of the
protrusions, and the distal ends 54 of the protrusions 32. A
portion of the fibers in the second layer form part of: the first
region 40, the side walls 56 of the protrusions, and the distal
ends 54 of the protrusions 32.
[0127] As shown in FIG. 16, the nonwoven layer in contact with the
male forming element (e.g., 30B) may have a large portion at the
distal end 54B of the protrusion 32B with a similar basis weight to
the original nonwoven (that is, to the first region 40). As shown
in FIG. 17, the basis weight in the sidewalls 56B of the protrusion
32B and near the base opening 44 may be lower than the basis weight
of the first region 40 of the nonwoven layer and the distal end 54
of the protrusion 32B. As shown in FIG. 18, the nonwoven layer in
contact with the female forming element (e.g., 30A) may, however,
have significantly less basis weight in the cap 52A of the
protrusion 32A than in the first region 40 of the nonwoven layer.
As shown in FIG. 19, the sidewalls 56A of the protrusion 32A may
have less basis weight than the first region 40 of the nonwoven.
FIGS. 19A and 19B show that the nonwoven layer 30A in contact with
the female forming element may have a fiber concentration that is
greatest in the first region 40 (at the upper part of the image in
FIG. 19A) and lowest at the distal end 54 of the protrusion 32. The
fiber concentration in the side wall 56A, in this case, may be less
than that of the first region 40, but greater than that at the
distal end 54 of the protrusion 32.
[0128] Forming deformations in the nonwoven material may also
affect the bonds 46 (thermal point bonds) within the layer (or
layers). In some embodiments, the bonds 46 within the distal end 54
of the protrusions 32 may remain intact (not be disrupted) by the
deformation process that formed the protrusions 32. In the side
walls 56 of the protrusions 32, however, the bonds 46 originally
present in the precursor web may be disrupted. When it is said that
the bonds 46 may be disrupted, this can take several forms. The
bonds 46 can be broken and leave remnants of a bond. In other
cases, such as where the nonwoven precursor material is
underbonded, the fibers can disentangle from a lightly formed bond
site (similar to untying a bow), and the bond site will essentially
disappear. In some cases, after the deformation process, the side
walls 56 of at least some of the protrusions 32 may be
substantially free (or completely free) of thermal point bonds.
[0129] Numerous embodiments of dual layer and other multiple layer
structures are possible. For example, a nonwoven layer 30B such as
that shown in FIGS. 16 and 17 could be oriented with its base
openings facing upward, and could serve as a topsheet of a dual or
multiple layer nonwoven structure (with at least one other layer
serving as an acquisition layer). In this embodiment, the bonds 46
within first region 40 of nonwoven layer 30B and the distal end 54
of the protrusions 32 remain intact. In the side walls 56 of the
protrusions 32, however, the bonds 46 originally present in the
precursor web are disrupted such that the side walls 56 are
substantially free of thermal point bonds. Such a topsheet could be
combined with an acquisition layer in which the concentration of
fibers within the layer 30A in the first region 40 and the distal
end 54 of the protrusions 32 is also greater than the concentration
of fibers in the side walls 56 of the protrusions 32.
[0130] In other embodiments, the acquisition layer 30A described in
the preceding paragraph may have thermal point bonds 46 within
first region 40 of nonwoven layer 30B and the distal end 54 of the
protrusions 32 that remain intact. In the side walls 56 of the
protrusions 32, however, the bonds 46 originally present in the
precursor web comprising the acquisition layer 30A are disrupted
such that the side walls 56 of the acquisition layer 30A are
substantially free of thermal point bonds. In other cases, the
thermal point bonds in the acquisition layer 30A at the top of the
protrusions 32 may also be disrupted so that the distal end 54 of
at least some of the protrusions are substantially or completely
free of thermal point bonds.
[0131] In other embodiments, a dual layer or multiple layer
structure may comprise a topsheet and an acquisition layer that is
oriented with its base openings facing upward in which the
concentration of fibers at the distal end 54 of each layer
(relative to other portions of the layer) differs between layers.
For example, in one embodiment, in the layer that forms the
topsheet (second layer), the concentration of fibers in the first
region and the distal ends of the protrusions are each greater than
the concentration of fibers in the side walls of the protrusions.
In the layer that forms the acquisition layer (first layer), the
concentration of fibers in the first region of the acquisition
layer may be greater than the concentration of fibers in the distal
ends of the protrusions. In a variation of this embodiment, the
concentration of fibers in the first region of the first layer
(acquisition layer) is greater than the concentration of fibers in
the side walls of the protrusions in the first layer, and the
concentration of fibers in the side walls of the protrusions in the
first layer is greater than the concentration of fibers forming the
distal ends of the protrusions in the first layer. In some
embodiments in which the first layer comprises a spunbond nonwoven
material (in which the precursor material had thermal point bonds
distributed substantially evenly throughout), a portion of the
fibers that form the first region in the first layer comprise
thermal point bonds, and the portion of the fibers in the first
layer forming the side walls and distal ends of at least some of
the protrusions may be substantially free of thermal point bonds.
In these embodiments, in at least some of the protrusions, at least
some of the fibers in the first layer may form a nest or circle
around (that is, encircle) the perimeter of the protrusion at the
transition between the wide wall and the base of the protrusion as
shown in FIG. 19.
[0132] The base openings 44 can be of any suitable shape and size.
The shape of the base opening 44 will typically be similar to, or
the same as, the plan view shape of the corresponding protrusions
32. The base opening 44 may have a width that is greater than about
any of the following dimensions before (and after compression): 0.5
mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, or any 0.1 mm increment above 1
mm. The width of the base opening 44 may be in a range that is from
any of the foregoing amounts up to about 4 mm, or more. The base
openings 44 may have a length that ranges from about 1.5 mm or less
to about 10 mm, or more. The base openings 44 may have an aspect
ratio that ranges from about 1:1 to 20:1, alternatively from about
1:1 to 10:1. Measurements of the dimensions of the base opening can
be made on a photomicrograph. When the size of the width of the
base opening 44 is specified herein, it will be appreciated that if
the openings are not of uniform width in a particular direction,
the width, W.sub.O, is measured at the widest portion as shown in
FIG. 6. The nonwoven materials of the present invention and the
method of making the same may create deformations with a wider
opening than certain prior structures which have a narrow base.
This allows the base openings 44 to be more visible to the naked
eye. The width of the base opening 44 is of interest because, being
the narrowest portion of the opening, it will be most restrictive
of the size of the opening. The deformations retain their wide base
openings 44 after compression perpendicular to the plane of the
first region 40.
[0133] The deformations may compress under load. In some cases, it
may be desirable that the load is low enough so that, if the
nonwoven is worn against a wearer's body, with the deformations in
contact with the wearer's body, the deformations will be soft and
will not imprint the skin. This applies in cases where either the
protrusions 32 or the base openings 44 are oriented so that they
are in contact with the wearer's body. For example, it may be
desirable for the deformations to compress under pressures of 2 kPa
or less. In other cases, it will not matter if the deformations
imprint the wearer's skin. It may be desirable for at least one of
the protrusions 32 in the nonwoven material 30 to collapse or
buckle in the controlled manner described below under the 7 kPa
load when tested in accordance with the Accelerated Compression
Method in the Test Methods section below. Alternatively, at least
some, or in other cases, a majority of the protrusions 32 may
collapse in the controlled manner described herein. Alternatively,
substantially all of the protrusions 32 may collapse in the
controlled manner described herein. The ability of the protrusions
32 to collapse may also be measured under a load of 35 kPa. The 7
kPa and 35 kPa loads simulate manufacturing and compression
packaging conditions. Wear conditions can range from no or limited
pressure (if the wearer is not sitting on the absorbent article) up
to 2 kPa, 7 kPa, or more.
[0134] The protrusions 32 may collapse in a controlled manner after
compression to maintain the wide opening 44 at the base. FIG. 13
shows the first surface 34 of a nonwoven material 30 according to
the present invention after it has been subjected to compression.
FIG. 14 is a side view of a single downwardly-oriented protrusion
32 after it has been subjected to compression. As shown in FIG. 13,
when the protrusions 32 have been compressed, there appears to be a
higher concentration of fibers in the form of a ring of increased
opacity 80 around the base opening 44. When a compressive force is
applied to the nonwoven materials, the side walls 56 of the
protrusions 32 may collapse in a more desirable/controlled manner
such that the side walls 56 become concave and fold into regions of
overlapping layers (such as into an s-shape/accordion-shape). The
ring of increased opacity 80 represents folded layers of material.
In other words, the protrusions 32 may have a degree of dimensional
stability in the X-Y plane when a Z-direction force is applied to
the protrusions. It is not necessary that the collapsed
configuration of the protrusions 32 be symmetrical, only that the
collapsed configuration prevent the protrusions 32 from flopping
over or pushing back into the original plane of the nonwoven, and
significantly reducing the size of the base opening (for example,
by 50% or more). For example, as shown in FIG. 14, the left side of
the protrusion 32 can form a z-folded structure, and the right side
of the protrusion does not, but still appears, when viewed from
above, to have higher opacity due to a degree of overlapping of the
material in the folded portion. Without wishing to be bound to any
particular theory, it is believed that the wide base opening 44 and
large cap 52 (greater than the width of the base opening 44),
combined with the lack of a pivot point, causes the protrusions 32
to collapse in a controlled manner (prevents the protrusion 32 from
flopping over). Thus, the protrusions 32 are free of a hinge
structure that would otherwise permit them to fold to the side when
compressed. The large cap 52 also prevents the protrusion 32 from
pushing back into the original plane of the nonwoven.
[0135] The deformations can be disposed in any suitable density
across the surface of the nonwoven material 30. The deformations
may, for example, be present in a density of: from about 5 to about
100 deformations; alternatively from about 10 to about 50
deformations; alternatively from about 20 to about 40 deformations,
in an area of 10 cm.sup.2.
[0136] The deformations can be disposed in any suitable arrangement
across the plane of the nonwoven material. Suitable arrangements
include, but are not limited to: staggered arrangements, and
zones.
[0137] The nonwoven webs 30 described herein can comprise any
suitable component or components of an absorbent article. For
example, the nonwoven webs can comprise the topsheet of an
absorbent article, or as shown in FIG. 25, if the nonwoven web 30
comprises more than one layer, the nonwoven web can comprise a
combined topsheet 84 and acquisition layer 86 of an absorbent
article, such as diaper 82. The diaper 82 shown in FIGS. 25-27 also
comprises an absorbent core 88, a backsheet 94, and a distribution
layer 96. The nonwoven materials of the present disclosure may also
form an outer cover of an absorbent article, such as backsheet 94.
The nonwoven webs 30 can be placed in an absorbent article with the
deformations 31 in any suitable orientation. For example, the
protrusions 32 can be oriented up or down. In other words, the
protrusions 32 may be oriented toward the absorbent core 88 as
shown in FIG. 26. Thus, for example, it may be desirable for the
protrusions 32 to point inward toward the absorbent core 88 in a
diaper (that is, away from the body-facing side and toward the
garment-facing side), or other absorbent article. Alternatively,
the protrusions 32 may be oriented so that they extend away from
the absorbent core of the absorbent article as shown in FIG. 27. In
still other embodiments, the nonwoven webs 30 can be made so that
they have some protrusions 32 that are oriented upward, and some
that are oriented downward. Without wishing to be bound to any
particular theory, it is believed that such a structure may be
useful in that the protrusions that are oriented upward can be more
effective for cleaning the body from exudates, while the
protrusions that are oriented downward can be more effective for
absorption of exudates into the absorbent core. Therefore, without
being bound to theory, a combination of these two protrusion
orientations will offer advantage that the same product can fulfill
the two functions.
[0138] A two or more layer nonwoven structure may provide fluid
handling benefits. If the layers are integrated together, and the
protrusions 32 are oriented toward the absorbent core, they may
also provide a dryness benefit. It may be desirable, on the other
hand, for the protrusions 32 to point outward, away from the
absorbent core in a pad for a wet or dry mop to provide a cleaning
benefit. In some embodiments, when the nonwoven web 30 is
incorporated into an absorbent article, the underlying layers can
be either substantially, or completely free, of tow fibers.
Suitable underlying layers that are free of tow fibers may, for
example, comprise a layer or patch of cross-linked cellulose
fibers. In some cases, it may be desirable that the nonwoven
material 30 is not entangled with (that is, is free from
entanglement with) another web.
[0139] The layers of the nonwoven structure (e.g., a topsheet
and/or acquisition layer) may be colored. Color may be imparted to
the webs in any suitable manner including, but not limited to by
color pigmentation. The term "color pigmentation" encompasses any
pigments suitable for imparting a non-white color to a web. This
term therefore does not include "white" pigments such as TiO.sub.2
which are typically added to the layers of conventional absorbent
articles to impart them with a white appearance. Pigments are
usually dispersed in vehicles or substrates for application, as for
instance in inks, paints, plastics or other polymeric materials.
The pigments may for example be introduced in a polypropylene
masterbatch. A masterbatch comprises a high concentration of
pigment and/or additives which are dispersed in a carrier medium
which can then be used to pigment or modify the virgin polymer
material into a pigmented bicomponent nonwoven. An example of
suitable colored masterbatch material that can be introduced is
Pantone color 270 Sanylen violet PP 42000634 ex Clariant, which is
a PP resin with a high concentration of violet pigment. Typically,
the amount of pigments introduced by weight of the webs may be of
from 0.3%-2.5%. Alternatively, color may be imparted to the webs by
way of impregnation of a colorant into the substrate. Colorants
such as dyes, pigments, or combinations may be impregnated in the
formation of substrates such as polymers, resins, or nonwovens. For
example, the colorant may be added to molten batch of polymer
during fiber or filament formation.
[0140] Precursor Materials.
[0141] The nonwoven materials of the present invention can be made
of any suitable nonwoven materials ("precursor materials"). The
nonwoven webs can be made from a single layer, or multiple layers
(e.g., two or more layers). If multiple layers are used, they can
be comprised of the same type of nonwoven material, or different
types of nonwoven materials. In some cases, the precursor materials
may be free of any film layers.
[0142] The fibers of the nonwoven precursor material(s) can be made
of any suitable materials including, but not limited to natural
materials, synthetic materials, and combinations thereof. Suitable
natural materials include, but are not limited to cellulose, cotton
linters, bagasse, wool fibers, silk fibers, etc. Cellulose fibers
can be provided in any suitable form, including but not limited to
individual fibers, fluff pulp, drylap, liner board, etc. Suitable
synthetic materials include, but are not limited to nylon, rayon
and polymeric materials. Suitable polymeric materials include, but
are not limited to: polyethylene (PE), polyester, polyethylene
terephthalate (PET), polypropylene (PP), and co-polyester. In some
embodiments, however, the nonwoven precursor materials can be
either substantially, or completely free, of one or more of these
materials. For example, in some embodiments, the precursor
materials may be substantially free of cellulose, and/or exclude
paper materials. In some embodiments, one or more precursor
materials can comprise up to 100% thermoplastic fibers. The fibers
in some cases may, therefore, be substantially non-absorbent. In
some embodiments, the nonwoven precursor materials can be either
substantially, or completely free, of tow fibers.
[0143] The precursor nonwoven materials can comprise any suitable
types of fibers. Suitable types of fibers include, but are not
limited to: monocomponent, bicomponent, and/or biconstituent,
non-round (e.g., shaped fibers (including but not limited to fibers
having a trilobal cross-section) and capillary channel fibers). The
fibers can be of any suitable size. The fibers may, for example,
have major cross-sectional dimensions (e.g., diameter for round
fibers) ranging from 0.1-500 microns. Fiber size can also be
expressed in denier, which is a unit of weight per length of fiber.
The constituent fibers may, for example, range from about 0.1
denier to about 100 denier. The constituent fibers of the nonwoven
precursor web(s) may also be a mixture of different fiber types,
differing in such features as chemistry (e.g., PE and PP),
components (mono- and bi-), shape (i.e. capillary channel and
round) and the like.
[0144] The nonwoven precursor webs can be formed from many
processes, such as, for example, air laying processes, wetlaid
processes, meltblowing processes, spunbonding processes, and
carding processes. The fibers in the webs can then be bonded via
spunlacing processes, hydroentangling, calendar bonding,
through-air bonding and resin bonding. Some of such individual
nonwoven webs may have bond sites 46 where the fibers are bonded
together.
[0145] In the case of spunbond webs, the web may have a thermal
point bond 46 pattern that is not highly visible to the naked eye.
For example, dense thermal point bond patterns are equally and
uniformly spaced are typically not highly visible. After the
material is processed through the mating male and female rolls, the
thermal point bond pattern is still not highly visible.
Alternatively, the web may have a thermal point bond pattern that
is highly visible to the naked eye. For example, thermal point
bonds that are arranged into a macro-pattern, such as a diamond
pattern, are more visible to the naked eye. After the material is
processed through the mating male and female rolls, the thermal
point bond pattern is still highly visible and can provide a
secondary visible texture element to the material.
[0146] 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 30. For example, the
topsheet of a topsheet/acquisition layer laminate or composite may
have a basis weight from about 8 to about 40 gsm, or from about 8
to about 30 gsm, or from about 8 to about 20 gsm. The acquisition
layer may have a basis weight from about 10 to about 120 gsm, or
from about 10 to about 100 gsm, or from about 10 to about 80 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 30. The nonwoven precursor webs may have a
density that is between about 0.01 and about 0.4 g/cm.sup.3
measured at 0.3 psi (2 kPa).
[0147] The precursor nonwoven webs may have certain desired
characteristics. The precursor nonwoven web(s) each have a first
surface, a second surface, and a thickness. The first and second
surfaces of the precursor nonwoven web(s) may be generally planar.
It is typically desirable for the precursor nonwoven web materials
to have extensibility to enable the fibers to stretch and/or
rearrange into the form of the protrusions. If the nonwoven webs
are comprised of two or more layers, it may be desirable for all of
the layers to be as extensible as possible. Extensibility is
desirable in order to maintain at least some non-broken fibers in
the sidewalls around the perimeter of the protrusions. It may be
desirable for individual precursor webs, or at least one of the
nonwovens within a multi-layer structure, to be capable of
undergoing an apparent elongation (strain at the breaking force,
where the breaking force is equal to the peak force) of greater
than or equal to about one of the following amounts: 100% (that is
double its unstretched length), 110%, 120%, or 130% up to about
200%. It is also desirable for the precursor nonwoven webs to be
capable of undergoing plastic deformation to ensure that the
structure of the deformations is "set" in place so that the
nonwoven web will not tend to recover or return to its prior
configuration.
[0148] Materials that are not extensible enough (e.g., inextensible
PP) may form broken fibers around much of the perimeter of the
deformation, and create more of a "hanging chad" 90 (i.e., the cap
52 of the protrusions 32 may be at least partially broken from and
separated from the rest of the protrusion (as shown in FIG. 20).
The area on the sides of the protrusion where the fibers are broken
is designated with reference number 92. Materials such as that
shown in FIG. 20 will not be suitable for a single layer structure,
and, if used, will typically be part of a composite multi-layer
structure in which another layer has protrusions 32 as described
herein.
[0149] When the fibers of a nonwoven web are not very extensible,
it may be desirable for the nonwoven to be underbonded as opposed
to optimally bonded. A thermally bonded nonwoven web's tensile
properties can be modified by changing the bonding temperature. A
web can be optimally or ideally bonded, underbonded, or overbonded.
Optimally or ideally bonded webs are characterized by the highest
breaking force and apparent elongation with a rapid decay in
strength after reaching the breaking force. Under strain, bond
sites fail and a small amount of fibers pull out of the bond site.
Thus, in an optimally bonded nonwoven, the fibers 38 will stretch
and break around the bond sites 46 when the nonwoven web is
strained beyond a certain point. Often there is a small reduction
in fiber diameter in the area surrounding the thermal point bond
sites 46. Underbonded webs have a lower breaking force and apparent
elongation when compared to optimally bonded webs, with a slow
decay in strength after reaching the breaking force. Under strain,
some fibers will pull out from the thermal point bond sites 46.
Thus, in an underbonded nonwoven, at least some of the fibers 38
can be separated easily from the bond sites 46 to allow the fibers
38 to pull out of the bond sites and rearrange when the material is
strained. Overbonded webs also have a lowered breaking force and
elongation when compared to optimally bonded webs, with a rapid
decay in strength after reaching the breaking force. The bond sites
look like films and result in complete bond site failure under
strain.
[0150] When the nonwoven web comprises two or more layers, the
different layers can have the same properties, or any suitable
differences in properties relative to each other. In one
embodiment, the nonwoven web 30 can comprise a two layer structure
that is used in an absorbent article. For convenience, the
precursor webs and the material into which they are formed will
generally be referred to herein by the same reference numbers.
However, in some cases, for additional clarity the precursor web
may be designated as 30'. As described above, one of the layers, a
second layer 30B, can serve as the topsheet of the absorbent
article, and the first layer 30A can be an underlying layer (or
sub-layer) and serve as an acquisition layer. The acquisition layer
30A receives liquids that pass through the topsheet and distributes
them to underlying absorbent layers. In such a case, the topsheet
30B may be less hydrophilic than sub-layer(s) 30A, which may lead
to better dewatering of the topsheet. In other embodiments, the
topsheet can be more hydrophilic than the sub-layer(s). In some
cases, the pore size of the acquisition layer may be reduced, for
example via using fibers with smaller denier or via increasing the
density of the acquisition layer material, to better dewater the
pores of the topsheet.
[0151] The second nonwoven layer 30B that may serve as the topsheet
can have any suitable properties. Properties of interest for the
second nonwoven layer, when it serves as a topsheet, in addition to
sufficient extensibility and plastic deformation may include
uniformity and opacity. As used herein, "uniformity" refers to the
macroscopic variability in basis weight of a nonwoven web. As used,
herein, "opacity" of nonwoven webs is a measure of the
impenetrability of visual light, and is used as visual
determination of the relative fiber density on a macroscopic scale.
As used herein, "opacity" of the different regions of a single
nonwoven deformation is determined by taking a photomicrograph at
20.times. magnification of the portion of the nonwoven containing
the deformation against a black background. Darker areas indicate
relatively lower opacity (as well as lower basis weight and lower
density) than white areas.
[0152] Several examples of nonwoven materials suitable for use as
the second nonwoven layer 30B include, but are not limited to:
spunbonded nonwovens; carded nonwovens; and other nonwovens with
high extensibility (apparent elongation in the ranges set forth
above) and sufficient plastic deformation to ensure the structure
is set and does not have significant recovery. One suitable
nonwoven material as a topsheet for a topsheet/acquisition layer
composite structure may be an extensible spunbonded nonwoven
comprising polypropylene and polyethylene. The fibers can comprise
a blend of polypropylene and polyethylene, or they can be
bi-component fibers, such as a sheath-core fiber with polyethylene
on the sheath and polypropylene in the core of the fiber. Another
suitable material is a bi-component fiber spunbonded nonwoven
comprising fibers with a polyethylene sheath and a
polyethylene/polypropylene blend core.
[0153] The first nonwoven layer 30A that may, for example, serve as
the acquisition layer can have any suitable properties. Properties
of interest for the first nonwoven layer, in addition to sufficient
extensibility and plastic deformation may include uniformity and
opacity. If the first nonwoven layer 30A serves as an acquisition
layer, its fluid handling properties must also be appropriate for
this purpose. Such properties may include: permeability, porosity,
capillary pressure, caliper, as well as mechanical properties such
as sufficient resistance to compression and resiliency to maintain
void volume. Suitable nonwoven materials for the first nonwoven
layer when it serves as an acquisition layer include, but are not
limited to: spunbonded nonwovens; through-air bonded ("TAB") carded
nonwoven materials; spunlace nonwovens; hydroentangled nonwovens;
and, resin bonded carded nonwoven materials. Of course, the
composite structure may be inverted and incorporated into an
article in which the first layer 30A serves as the topsheet and the
second layer 30B serves as an acquisition layer. In such cases, the
properties and exemplary methods of the first and second layers
described herein may be interchanged.
[0154] The layers of a two or more layered nonwoven web structure
can be combined together in any suitable manner. In some cases, the
layers can be unbonded to each other and held together autogenously
(that is, by virtue of the formation of deformations therein). For
example, both precursor webs 30A and 30B contribute fibers to
deformations in a "nested" relationship that joins the two
precursor webs together, forming a multi-layer web without the use
or need for adhesives or thermal bonding between the layers. In
other embodiments, the layers can be joined together by other
mechanisms. If desired an adhesive between the layers, ultrasonic
bonding, chemical bonding, resin or powder bonding, thermal
bonding, or bonding at discrete sites using a combination of heat
and pressure can be selectively utilized to bond certain regions or
all of the precursor webs. In addition, the multiple layers may be
bonded during processing, for example, by carding one layer of
nonwoven onto a spunbond nonwoven and thermal point bonding the
combined layers. In some cases, certain types of bonding between
layers may be excluded. For example, the layers of the present
structure may be non-hydroentangled together.
[0155] If adhesives are used, they can be applied in any suitable
manner or pattern including, but not limited to: slots, spirals,
spray, and curtain coating. Adhesives can be applied in any
suitable amount or basis weight including, but not limited to
between about 0.5 and about 30 gsm, alternatively between about 2
and about 5 gsm. Examples of adhesives could include hot melt
adhesives, such as polyolefins and styrene block copolymers.
[0156] A certain level of adhesive may reduce the level of fuzz on
the surface of the nonwoven material even though there may be a
high percentage of broken fibers as a result of the deformation
process. Glued dual-layer laminates produced as described herein
are evaluated for fuzz. The method utilizes a Martindale Abrasion
Tester, based upon ASTM D4966-98. After abrading the samples, they
are graded on a scale of 1-10 based on the degree of fiber pilling
(1=no fiber pills; 10=large quantity and size of fiber pills). The
protrusions are oriented away from the abrader so the land area in
between the depressions is the primary surface abraded. Even though
the samples may have a significant amount of fiber breakage
(greater than 25%, sometimes greater than 50%) in the side walls of
the protrusions/depressions, the fuzz value may be low (around 2)
for several different material combinations, as long as the layers
do not delaminate during abrasion. Delamination is best prevented
by glue basis weight, for example a glue basis weight greater than
3 gsm, and glue coverage.
[0157] When the precursor nonwoven web comprises two or more
layers, it may be desirable for at least one of the layers to be
continuous, such as in the form of a web that is unwound from a
roll. In some embodiments, each of the layers can be continuous. In
alternative embodiments, such as shown in FIG. 24, one or more of
the layers can be continuous, and one or more of the layers can
have a discrete length. The layers may also have different widths.
For example, in making a combined topsheet and acquisition layer
for an absorbent article, the nonwoven layer that will serve as the
topsheet may be a continuous web, and the nonwoven layer that will
serve as the acquisition layer may be fed into the manufacturing
line in the form of discrete length (for example, rectangular, or
other shaped) pieces that are placed on top of the continuous web.
Such an acquisition layer may, for example, have a lesser width
than the topsheet layer. The layers may be combined together as
described above.
III. Methods of Making the Nonwoven Materials
[0158] The nonwoven materials are made by a method comprising the
steps of: a) providing at least one precursor nonwoven web; b)
providing an apparatus comprising a pair of forming members
comprising a first forming member (a "male" forming member) and a
second forming member (a "female" forming member); and c) placing
the precursor nonwoven web(s) between the forming members and
mechanically deforming the precursor nonwoven web(s) with the
forming members. The forming members have a machine direction (MD)
orientation and a cross-machine direction (CD) orientation.
[0159] The first and second forming members can be plates, rolls,
belts, or any other suitable types of forming members. In some
embodiments, it may be desirable to modify the apparatus for
incrementally stretching a web described in U.S. Pat. No.
8,021,591, Curro, et al. entitled "Method and Apparatus for
Incrementally Stretching a Web" by providing the activation members
described therein with the forming elements of the type described
herein. In the embodiment of the apparatus 100 shown in FIG. 21,
the first and second forming members 102 and 104 are in the form of
non-deformable, meshing, counter-rotating rolls that form a nip 106
therebetween. The precursor web(s) is/are fed into the nip 106
between the rolls 102 and 104. Although the space between the rolls
102 and 104 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(s) to the extent possible.
[0160] First Forming Member.
[0161] The first forming member (such as "male roll") 102 has a
surface comprising a plurality of first forming elements which
comprise discrete, spaced apart male forming elements 112. 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.
[0162] As shown in FIG. 22, the male forming elements 112 have a
base 116 that is joined to (in this case is integral with) the
first forming member 102, a top 118 that is spaced away from the
base, and side walls (or "sides") 120 that extend between the base
116 and the top 118 of the male forming elements. The male elements
112 may also have a transition portion or region 122 between the
top 118 and the side walls 120. The male elements 112 also have a
plan view periphery, and a height H.sub.1 (the latter being
measured from the base 116 to the top 118). The discrete elements
on the male roll may have a top 118 with 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 deformation. The
male elements 112 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 male elements 112 will be consider the length, and the
dimension perpendicular thereto will be considered to be the width
of the male element. The male elements 112 may have any suitable
configuration.
[0163] The base 116 and the top 118 of the male elements 112 may
have any suitable plan view configuration, including but not
limited to: a rounded diamond configuration as shown in FIGS. 21
and 22, an American football-like shape, triangle, circle, clover,
a heart-shape, teardrop, oval, or an elliptical shape. The
configuration of the base 116 and the configuration of the top 118
of the male elements 112 may be in any of the following
relationships to each other: the same, similar, or different. The
top 118 of the male elements 112 can be flat, rounded, or any
configuration therebetween.
[0164] The side walls 120 of the male elements 112 may have any
suitable configuration. The male elements 112 may have vertical
side walls 120, or tapered side walls 120. By vertical side walls,
it is meant that the side walls 120 have zero degree side wall
angles relative to the perpendicular from the base 116 of the side
wall. In other embodiments, as shown in FIG. 22A, the side walls
120 can be tapered inwardly toward the center of the male forming
elements 112 from the base 116 to the top 118 so that the side
walls 120 form an angle, A, greater than zero. In still other
embodiments, as shown in FIG. 22B, the male forming elements 112
may have a wider top surface than base so that the side walls 120
are angled outwardly away from the center of the male forming
elements 112 from the base 116 to the top 118 of the male elements
112 (that is, the side walls may be undercut). The side wall angle
can be the same on all sides of the male elements 112.
Alternatively, the male elements 112 may have a different side wall
angle on one or more of their sides. For example, the leading edge
(or "LE") and trailing edge (or "TE") of the male elements (with
respect to the machine direction) may have equal side wall angles,
and the sides of the male elements may have equal side wall angles,
but the side wall angles of the LE and TE may be different from the
side wall angle of the sides. In certain embodiments, for example,
the side wall angle of the sides of the male elements 112 may be
vertical, and the side walls of the LE and TE may be slightly
undercut.
[0165] The transition region or "transition" 122 between the top
118 and the side walls 120 of the male elements 112 may also be of
any suitable configuration. The transition 122 can be in the form
of a sharp edge (as shown in FIG. 22C) in which case there is zero,
or a minimal radius where the side walls 120 and the top 118 of the
male elements meet. That is, the transition 122 may be
substantially angular, sharp, non-radiused, or non-rounded. In
other embodiments, such as shown in FIG. 22, the transition 122
between the top 118 and the side walls 120 of the male elements 112
can be radiused, or alternatively beveled. Suitable radiuses
include, but are not limited to: zero (that is, the transition
forms a sharp edge), 0.01 inch (about 0.25 mm), 0.02 inch (about
0.5 mm), 0.03 inch (about 0.76 mm), 0.04 inch (about 1 mm) (or any
0.01 inch increment above 0.01 inch), up to a fully rounded male
element as shown in FIG. 22D.
[0166] In some cases, it may be desired to roughen the surface of
all, or a portion, of the male elements 112. The surface of the
male elements 112 can be roughened in any suitable manner. The
surface of the male elements 112 can be roughened, for example, by:
media blasting (that is, roughened with shot or "shot blasted");
wet blasting (roughed with water jets); plasma coating, machining,
or knurling (i.e., pressure embossing of surface of first forming
member); or combinations of the same. The roughened configuration
and characteristics of the male elements 112 will depend on the
type of process used to roughen the same. The roughening will
typically provide at least the top 118 of at least some of the male
elements 112 with greater than or equal to two discrete first
surface texture elements protruding therefrom.
[0167] If a media or wet blasting process is used to roughen the
surface of the male elements 112, such processes will typically
form a plurality of randomly arranged pits 138 in the surface of
the male elements 112 that form discrete randomly arranged raised
elements or "first surface texture elements" 140 therebetween. The
surface of the male elements 112, as shown in FIG. 22E, may
resemble sandpaper. The surface of the male elements 112 may be
described in terms of the fineness of the media used to roughen the
same and/or the number of raised elements per area (such as per
square inch). For example the surface of the male elements 112 may
be roughened by 80, 120 or 150 grit media. The roughened surface
can be described using the Surface Texture Characterization method
outlined below.
[0168] If knurling is used to roughen the surface of the male
elements 112, this will typically be performed by contacting the
first forming member 102 with a rotating patterned roll made of a
harder material than that of the first forming member. As shown in
FIG. 22G, knurling will result in displacing material on the top
surface 118 of the male elements 112 to create a pattern of valleys
144 with raised areas 146 therebetween. Knurling may modify the
surface of a female forming member in the same or a similar manner.
Such processes will typically form a macroscale texture (valleys
144 and raised areas 146) on the top surface 118 of the male
elements 112. Such a pattern may, for example, appear in plan view
as a plurality of diamond-shaped elements, diagonal lines, or
straight (MD or CD) lines with a diametral pitch that may range,
for example, from about 60 (coarse) to about 160 (extra fine). The
macroscale texture can be characterized using a microscope with,
for example, a 60X field of view. The spacing or pitch P of the
elements 144 and 146 may range from about 0.5--about 2.0 mm. The
height H.sub.2 of the macroscale texture elements may range from
about 0.1--about 2 mm, alternatively from about 0.1-about 0.5 mm.
In addition to creating a macroscale texture, the knurling process
creates a microscale texture 148 on the top surfaces of the raised
macroscale texture elements 146, which can be described using the
Surface Texture Characterization method below.
[0169] As mentioned above, any suitable portion of the male
elements 112 may be roughened. Suitable portions of the male
elements that may be roughened include: the top surface 118; the
side walls 120; the transition region 122 between the top surface
and the side walls; or any combinations of the foregoing. For
example, in some embodiments the top surface 118 and the transition
region 122 may both be roughened. In other embodiments, only the
transition region 122 may be roughened. Often, the portion of the
male elements 112 that can be roughened will be dependent on the
process used to roughen the same.
[0170] The surfaces of several rolls textured using the techniques
mentioned above can be described using the Surface Texture
Characterization method set out below and contrasted to
non-roughened surfaces. As shown in FIG. 22F, non-roughened
surfaces may comprise machining marks, such as continuous ridges
and grooves, but they are very regular and have little height
compared to the textured surfaces described herein. For the male
rolls, analysis is made of the top surface 118 of the male elements
112 and the transition region 122 between the top surface and the
side walls. For a knurled female roll, the analysis is made on the
microtexture 148 that is on top of the macroscale raised texture
elements 146. The data in Table 1 below includes information on
various surface texture parameters, including Sq, Sxp, Str, and
Vmp. Table 1 shows the Sq of a microtextured surface may have a
value >1.7 .mu.m. The Sq may be up to about 15 .mu.m, or more.
The Sxp of a microtextured surface may have a value >3.0 .mu.m,
and may be up to about 50 .mu.m, or more. The Str of a
microtextured surface may have a value >0.27 .mu.m, and may be
up to about 1.0 .mu.m. The Vmp of a microtextured surface may have
a value >0.07 mL/m.sup.2, and may be up to about 1.1 mL/m.sup.2,
or more
TABLE-US-00001 TABLE 1 Surface Texture Characterization of Forming
Members Vmp Surface Sq (.mu.m) Sxp (.mu.m) Str (mL/m.sup.2)
Non-Roughened Male Top surface - male element 1 1.41 2.32 0.12 0.04
Top surface - male element 2 1.51 2.59 0.15 0.05 Transition region
0.86 1.71 0.25 0.05 Media Blasted Male (150 Grit) Top surface -
male element 1 2.18 4.17 0.81 0.11 Top surface - male element 2
2.17 4.26 0.96 0.12 Transition region 2.27 4.18 0.80 0.11 Media
Blasted Male (120 Grit) Top surface - male element 1 3.82 6.76 0.92
0.18 Top surface - male element 2 3.85 6.59 0.89 0.18 Transition
region 3.86 6.87 0.85 0.19 Knurled Female - Top of Knurl Top of
knurl - sample area 1 9.35 26.52 0.43 0.88 Top of knurl - sample
area 2 10.99 28.31 0.31 1.07 Top of knurl - sample area 3 9.59
26.97 0.40 0.88
[0171] Numerous other embodiments of the male forming elements 112
are possible. In other embodiments, the top 118 of the male
elements 112 can be of different shapes from those shown in the
drawings. In other embodiments, the male forming elements 112 can
be disposed in other orientations on the first forming member 102
rather than having their length oriented in the machine direction
(including CD-orientations, and orientations between the MD and
CD). The male forming elements 112 on the first forming member 102
may, but need not, all have the same configuration or properties.
In certain embodiments, the first forming member 102 can comprise
some male forming elements 112 having one configuration and/or
properties, and other male forming elements 112 having one or more
different configurations and/or properties.
[0172] The method of making the nonwoven materials may be run with
the first forming member 102 and male elements 112 under any of the
following conditions: at room temperature; with a chilled first
forming member 102 and/or male elements 112; or with heated first
forming member and/or male elements. In some cases, it may be
desired to avoid heating the first forming member 102 and/or male
elements 112. It may be desirable to avoid heating the first
forming member and/or the male elements altogether. Alternatively,
it may be desirable to avoid heating the first forming member
and/or the male elements to a temperature at or above that which
would cause the fibers of the nonwoven to fuse together. In some
cases, it may be desirable to avoid heating the first forming
member and/or the male elements to a temperature that is greater
than or equal to any of the following temperatures: 130.degree. C.,
110.degree. C., 60.degree. C., or greater than 25.degree. C.
[0173] Second Forming Member.
[0174] As shown in FIG. 21, the second forming member (such as
"female roll") 104 has a surface 124 having a plurality of cavities
or recesses 114 therein. The recesses 114 are aligned and
configured to receive the male forming elements 112 therein. Thus,
the male forming elements 112 mate with the recesses 114 so that a
single male forming element 112 fits within the periphery of a
single recess 114, and at least partially within the recess 114 in
the z-direction. The recesses 114 have a plan view periphery 126
that is larger than the plan view periphery of the male elements
112. As a result, the recess 114 on the female roll may completely
encompass the discrete male element 112 when the rolls 102 and 104
are intermeshed. The recesses 114 have a depth D.sub.1 shown in
FIG. 23. In some cases, the depth D.sub.1 of the recesses may be
greater than the height H.sub.1 of the male forming elements
112.
[0175] The recesses 114 have a plan view configuration, side walls
128, a top edge or rim 134 around the upper portion of the recess
where the side walls 128 meet the surface 124 of the second forming
member 104, and a bottom edge 130 around the bottom 132 of the
recesses where the side walls 128 meet the bottom 132 of the
recesses.
[0176] The recesses 114 may have any suitable plan view
configuration provided that the recesses can receive the male
elements 112 therein. The recesses 114 may have a similar plan view
configuration as the male elements 112. In other cases, some or all
of the recesses 114 may have a different plan view configuration
from the male elements 112.
[0177] The side walls 128 of the recesses 114 may be oriented at
any suitable angle. In some cases, the side walls 128 of the
recesses may be vertical. In other cases, the side walls 128 of the
recesses may be oriented at an angle. Typically, this will be an
angle that is tapered inwardly from the top 134 of the recess 114
to the bottom 132 of the recess. The angle of the side walls 128 of
the recesses can, in some cases, be the same as the angle of the
side walls 120 of the male elements 112. In other cases, the angle
of the side walls 128 of the recesses can differ from the angle of
the side walls 120 of the male elements 112.
[0178] The top edge or rim 134 around the upper portion of the
recess where the side walls 128 meet the surface 124 of the second
forming member 104 may have any suitable configuration. The rim 134
can be in the form of a sharp edge (as shown in FIG. 23) in which
case there is zero, or a minimal radius where the side walls 128 of
the recesses meet the surface of the second forming member 104.
That is, the rim 134 may be substantially angular, sharp,
non-radiused, or non-rounded. In other embodiments, such as shown
in FIG. 23A, the rim 134 can be radiused, or alternatively beveled.
Suitable radiuses include, but are not limited to: zero (that is,
form a sharp edge), 0.01 inch (about 0.25 mm), 0.02 inch (about 0.5
mm), 0.03 inch (about 0.76 mm), 0.04 inch (about 1 mm) (or any 0.01
inch increment above 0.01 inch) up to a fully rounded land area
between some or all of the side walls 128 around each recess 114.
The bottom edge 130 of the recesses 114 may be sharp or
rounded.
[0179] In some cases, it may be desired to roughen the surface of
all, or a portion, of the second forming member 104 and/or recesses
114 by providing the same with a plurality of discrete second
surface texture elements 142 thereon. The surface of the second
forming member 104 and/or recesses 114 can be roughened in any of
the manners described above for roughening the surface of the male
elements 112. This may provide the surface of the second forming
member 104 and/or recesses 114 with second surface texture elements
142 (and/or valleys 144, raised areas 146, and microscale texture
148 as shown in FIG. 22G) having the same or similar properties as
the first surface texture elements 140 on the male elements 112.
Thus, the second surface texture elements 142 can be distributed on
the surface of the second forming member 104 in a regular pattern
or a random pattern.
[0180] Any suitable portion of the second forming member 104 and/or
recesses 114 may be roughened. As shown in FIG. 23A, suitable
portions of the second forming member 104 and/or recesses 114 that
may be roughened include: the surface 124 of the second forming
member; the side walls 128 of the recesses; the top edge or rim 134
around the upper portion of the recess 114 where the side walls 128
meet the surface 124 of the second forming member 104; or any
combinations of the foregoing. For example, in some embodiments the
top surface 124 and the rim 134 may both be roughened. In other
embodiments, only the rims 134 of the recesses 114 may be
roughened. Often, the portion of the second forming member 104
and/or recesses 114 that can be roughened, as in the case of the
male elements, will be dependent on the process used to roughen the
same. FIG. 23B is a photograph of a second forming member 104
having a surface 124 that has been roughened with diamond type
knurling.
[0181] As discussed above, the recesses 114 may be deeper than the
height H.sub.1 of the male elements 112 so the nonwoven material is
not nipped (or squeezed) between the male and female rolls 102 and
104 to the extent possible. However, it is understood that passing
the precursor web(s) between two rolls with a relatively small
space therebetween will likely apply some shear and compressive
forces to the web(s). 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.
[0182] The depth of engagement (DOE) is a measure of the level of
intermeshing of the forming members. As shown in FIG. 23, the DOE
is measured from the top 118 of the male elements 112 to the
(outermost) surface 124 of the female forming member 114 (e.g., the
roll with recesses). The DOE should be sufficiently high, when
combined with extensible nonwoven materials, to create protrusions
32 having a distal portion or cap 52 with a maximum width that is
greater than the width of the base opening 44. The DOE may, for
example, range from at least about 1.5 mm, or less, to about 5 mm,
or more. In certain embodiments, the DOE may be between about 2.5
mm to about 5 mm, alternatively between about 3 mm and about 4 mm.
The formation of protrusions 32 having a distal portion with a
maximum width that is greater than the width of the base opening 44
is believed to differ from most embossing processes in which the
embossments typically take the configuration of the embossing
elements, which have a base opening that is wider than the
remainder of the embossments.
[0183] As shown in FIG. 23, there is a clearance, C, between the
sides 120 of the male elements 112 and the sides (or side walls)
128 of the recesses 114. 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 male element 112. For
example, the forming members can be designed so that there is less
clearance between the sides of the male elements 112 and the
adjacent side walls 128 of the recesses 114 than there is between
the side walls at the end of the male elements 112 and the adjacent
side walls of the recesses 114. In other cases, the forming members
can be designed so that there is more clearance between the sides
120 of the male elements 112 and the adjacent side walls 128 of the
recesses 114 than there is between the side walls at the end of the
male elements 112 and the adjacent side walls of the recesses. In
still other cases, there could be more clearance between the side
wall on one side of a male element 112 and the adjacent side wall
of the recess 114 than there is between the side wall on the
opposing side of the same male element 112 and the adjacent side
wall of the recess. For example, there can be a different clearance
at each end of a male element 112; and/or a different clearance on
each side of a male element 112. Clearances can range from about
0.005 inches (about 0.1 mm) to about 0.1 inches (about 2.5 mm).
[0184] Some of the aforementioned male element 112 configurations
alone, or in conjunction with the second forming member 104 and/or
recess 114 configurations may provide additional advantages. This
may be due to by greater lock of the nonwoven material on the male
elements 112, which may result in more uniform and controlled
strain on the nonwoven precursor material. This may produce more
well-defined protrusions 32 and a stronger visual signal for
consumers, giving the appearance of softness, absorbency, and/or
dryness.
[0185] The precursor nonwoven web 30 is placed between the forming
members 102 and 104. The precursor nonwoven web can be placed
between the forming members with either side of the precursor web
(first surface 34 or second surface 36) facing the first forming
member, male forming member 102. For convenience of description,
the second surface 36 of the precursor nonwoven web will be
described herein as being placed in contact with the first forming
member 102. (Of course, in other embodiments, the second surface 36
of the precursor nonwoven web can be placed in contact with the
second forming member 104.)
[0186] The precursor material is mechanically deformed with the
forming members 102 and 104 when a force is applied on the nonwoven
web with the forming members 102 and 104. The force can be applied
in any suitable manner. If the forming members 102 and 104 are in
the form of plates, the force will be applied when the plates are
brought together. If the forming members 102 and 104 are in the
form of counter-rotating rolls (or belts, or any combination of
rolls and belts), the force will be applied when the precursor
nonwoven web passes through the nip between the counter-rotating
elements. The force applied by the forming members impacts the
precursor web and mechanically deforms the precursor nonwoven
web.
[0187] Numerous additional processing parameters are possible. If
desired, the precursor nonwoven web may be heated before it is
placed between the forming members 102 and 104. If the precursor
nonwoven web is a multi-layer structure, any layer or layers of the
same can be heated before the layers are combined. Alternatively,
the entire multi-layer nonwoven web can be heated before it is
placed between the forming members 102 and 104. The precursor
nonwoven web, or layer(s) of the same, can be heated in any
suitable manner including, but not limited to using conductive
heating (such as by bringing the web(s) in contact with heated
rolls), or by convective heating (i.e., by passing the same under a
hot air knife or through an oven). The heating should be
non-targeted, and without the help of any agent. The first forming
member 102 and/or second forming member 104 (or any suitable
portion thereof) can also be heated. If desired, the web could be
additionally, or alternatively, heated after it is mechanically
deformed.
[0188] If the precursor material is fed between forming members
comprising counter-rotating rolls, several processing parameters
may be desirable. With regard to the speed at which the precursor
web is fed between the counter-rotating rolls, it may be desirable
to overfeed the web (create a negative draw) going into the nip 106
between the rolls. The surface speed of the metering roll
immediately upstream of the forming members 102 and 104 may be
between about 1 and 1.2 times the surface speed of the forming
members 102 and 104. It may be desirable for the tension on the
precursor web immediately before forming members 102 and 104 to be
less than about 5 lbs. force (about 22 N), alternatively less than
about 2 lbs. force (about 9 N) for a web width of 0.17 m. With
regard to the speed at which the deformed web 30 is removed from
between the counter-rotating rolls, it may be desirable to create a
positive draw coming out of the nip between the rolls. The surface
speed of the metering roll immediately downstream of the forming
members 102 and 104 may be between about 1 and 1.2 times the
surface speed of the forming members 102 and 104. It may be
desirable for the tension on the web immediately after the forming
members 102 and 104 to be less than about 5 lbs. force (about 22
N), alternatively less than about 2 lbs. force (about 9 N).
[0189] As shown in FIG. 24A, rather than feeding the precursor web
30' into the nip 106 between the forming members 102 and 104
without the precursor web 30' contacting any portion of the forming
members prior to or after the nip, it may be desirable for the web
to pre-wrap the second forming member 104 prior to entering the nip
106, and for the web 30 to post wrap second forming member 104
after passing through the nip.
[0190] The apparatus 100 for deforming the web can comprise
multiple nips for deforming portions of the web in the same
location such as described in U.S. Patent Publication No. US
2012/0064298 A1, Orr, et al. For example, the apparatus may
comprise a central roll and satellite rolls with equal DOE or
progressively greater DOE with each successive roll. This can
provide benefits such as reducing damage to the web and/or helping
to further ensure that the deformations are permanently set in the
web thereby preventing the web from recovering toward its
undeformed condition.
[0191] The apparatus for deforming the web can also comprise belts,
or other mechanisms, for holding down the longitudinal edges of the
web to prevent the web from being drawn inward in the cross-machine
direction.
[0192] When deforming multiple webs that are laminated together
with an adhesive, it may be desirable to chill the forming members
in order to avoid glue sticking to and fouling the forming members.
The forming members can be chilled using processes know in the art.
One such process could be an industrial chiller that utilizes a
coolant, such as propylene glycol. In some cases, it may be
desirable to operate the process in a humid environment such that a
layer of condensate forms on the forming members.
[0193] The apparatus 100 for deforming the web can be at any
suitable location in any suitable process. For example, the
apparatus can be located in-line with a nonwoven web making process
or a nonwoven laminate making process. Alternatively, the apparatus
100 can be located in-line in an absorbent article converting
process (such as after the precursor web is unwound and before it
is incorporated as part of the absorbent article).
[0194] The process forms a nonwoven web 30 comprising a generally
planar first region 40 and a plurality of discrete integral second
regions 42 that comprise deformations comprising protrusions 32
extending outward from the first surface 34 of the nonwoven web and
openings in the second surface 36 of the nonwoven web. (Of course,
if the second surface 36 of the precursor nonwoven web is placed in
contact with the second forming member 104, the protrusions will
extend outward from the second surface of the nonwoven web and the
openings will be formed in the first surface of the nonwoven web.)
Without wishing to be bound by any particular theory, it is
believed that the extensibility of the precursor web (or at least
one of the layers of the same) when pushed by the male forming
elements 112 into the recesses 114 with depth of engagement DOE
being less than the depth D.sub.1 of the recesses, stretches a
portion of the nonwoven web to form a deformation comprising a
protrusion with the enlarged cap and wide base opening described
above. (This can be analogized to sticking one's finger into an
uninflated balloon to stretch and permanently deform the material
of the balloon.)
[0195] In cases in which the precursor nonwoven material 30'
comprises more than one layer, and one of the layers is in the form
of discrete pieces of nonwoven material, as shown in FIG. 24, it
may be desirable for the deformations to be formed so that the base
openings 44 are in the continuous layer (such as 30B) and the
protrusions 32 extend toward the discrete layer (such as 30A). Of
course, in other embodiments, the deformations in such a structure
can be in the opposite orientation. The deformations can be
distributed in any suitable manner over the surfaces of such
continuous and discrete layers. For example, the deformations can:
be distributed over the full length and/or width of the continuous
layer; be distributed in an area narrower than the width of the
continuous layer; or be limited to the area of the discrete
layer.
[0196] The method of deforming the nonwoven materials described
herein may exclude (or be distinguishable from) the following
processes: hydroforming (hydroentangling); hydromolding; use of air
jets; rigid-to-resilient (e.g., steel/rubber) embossing; and the
use of a patterned surface against a flat anvil surface (e.g.,
rigid-to-rigid embossing). The method may also exclude (or be
distinguishable from) The Procter & Gamble Company's processes
for making Structural Elastic-Like Films ("SELF" processes). The
forming members used herein differ from the forming members used in
SELFing processes to form corrugated structures (and tufted
structures) in that the SELF teeth typically have a comparatively
small diameter tip, and the ridges of the mating ring roll only
border the SELF teeth on the sides, and not the front and back of
the teeth.
IV. Optional Processing Steps
[0197] The precursor web material 30' and/or the nonwoven web
material 30 with deformations therein can be subjected to an
optional additional processing step. The additional steps can
include, but are not limited to embossing and/or bonding.
[0198] A. Embossing.
[0199] The precursor web material 30' and/or the nonwoven web
material 30 with deformations therein can be subjected to an
optional embossing step. The precursor web material 30' can be
embossed prior to the formation of deformations therein. In
addition, or alternatively, the nonwoven web materials 30 described
herein may be embossed after the formation of deformations
(protrusions 32 and base openings 44) therein.
[0200] The embossments can be provided in any known manner.
Suitable embossing methods include, but are not limited to
rigid-to-resilient and rigid-to-rigid methods described in the
preceding section. If the precursor nonwoven material or the
nonwoven web materials 30 with deformations therein are embossed,
the embossments can be positioned in a specific location relative
to the deformations. That is, the embossments may be registered
with the deformations. In other embodiments, the embossments may be
randomly positioned relative to the deformations.
[0201] B. Optional Bonding Steps.
[0202] 1. Bonding Together Portions of a Deformed Nonwoven
Material.
[0203] a) Tip Bonding of a Deformed Nonwoven Material.
[0204] One optional bonding step involves bonding portions of the
deformed nonwoven material 30 together at the tops or distal ends
54 of the protrusions 32 ("tip bonding"). If the deformed nonwoven
material 30 is a single layer material, then this step will bond
the fibers in the layer together at the distal ends 54 of the
protrusions 32. If the deformed nonwoven material 30 is a dual or
multiple layer nonwoven material, then this step will bond the
fibers together at the distal ends 54 of the protrusions 32 and
will also bond fibers in each of the layers together at the distal
ends 54 of the protrusions 32.
[0205] FIG. 28 shows one embodiment of an apparatus 100 for
deforming the nonwoven material which includes an additional
bonding roll 150 for tip bonding the deformed nonwoven material 30.
As shown in FIG. 28, a precursor web 30' is fed into the deforming
nip 106 between first forming roll 102 and second forming roll 104.
After leaving the deforming nip 106, the deformed web 30 is wrapped
partially around the first forming roll, male roll 102. Vacuum,
hold down belts, or some other mechanism could be used to keep the
deformed web 30 seated on the first forming roll 102. While the web
30 is still in contact with the male roll 102, it passes through a
second nip 156 between male roll 102 and the additional bonding
roll 150. The additional bonding roll 150 can compress the fibers
at the distal ends 54 of the protrusions 32 sufficient to partially
melt and bond the fibers at this location together. The bonding
roll 150 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 150 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 156, the web may wrap the bonding roll 150 as shown in
FIG. 28, or it may wrap the male roll 102.
[0206] As shown in FIG. 29, this produces a protrusion 32 in which
the layers are bonded together at the tops (or distal ends 54) of
the protrusions 32. This will form a tip bonded portion 152. The
tip bonded portion 152 (and the bonds formed in the other optional
post bonding steps described herein) 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 post deformation bond sites will typically be registered with
the deformations in the deformed nonwoven, while thermal point
bonds are provided in a separate and different pattern in a
spunbonded precursor web. The bonding may result in a more
translucent (film-like) bonded portion 152. Placing a layer
containing color adjacent to the deformed material 30 could result
in color showing through primarily in the translucent bonded
portion 152, highlighting the protrusion 32.
[0207] Without wishing to be bound by any particular theory, it is
believed that bonding the layers together at the distal ends 54 of
the protrusions 32 may provide benefits which include: 1) increased
perception of the depth of the base openings 44 when the base
openings are oriented toward the consumer, as well as 2) improved
dryness (by reducing the hang-up of fluid in the bottoms of the
protrusions when the base openings 44 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
together.
[0208] b) Base Bonding of a Deformed Nonwoven Material.
[0209] Another optional bonding step involves bonding portions of
the deformed nonwoven material 30 together at base bond sites in
the undeformed first region 40 outside of the bases 50 of the
protrusions 32 ("base bonding"). If the deformed nonwoven material
30 is a single layer material, then this step will bond the fibers
of the layer together in the undeformed first region 40 outside of
the bases 50 of the protrusions 32. If the deformed nonwoven
material 30 is a dual or multiple layer nonwoven material, then
this step will bond the fibers together in the undeformed first
region 40 outside of the bases of the protrusions 32 and will also
bond fibers in each of the layers together in the undeformed first
region 40 outside of the bases of the protrusions 32.
[0210] FIG. 32 shows one embodiment of an apparatus 100 for
deforming the nonwoven material which includes an additional
bonding roll 160 for base bonding the deformed nonwoven material
30. In FIG. 32, the position of first and second forming rolls 102
and 104 are reversed and the female roll 104 is located on top of
the male roll 102. However, in other embodiments, the male roll 102
could be on top as shown in the tip bonding roll arrangements
described above. A precursor nonwoven web 30' is fed into the
deforming nip 106 between first forming roll 102 and second forming
roll 104. After leaving the deforming nip 106, the deformed web 30
is wrapped partially around the second forming roll, female roll
104. Vacuum, hold down belts, or some other mechanism could be used
to keep the deformed web 30 seated on the second forming roll 104.
While the web 30 is still in contact with the female roll 104, it
passes through a second nip 166 between female roll 104 and the
additional bonding roll 160. The additional bonding roll 160 can
compress the fibers in the undeformed first region 40 outside of
the bases 50 of the protrusions 32 sufficient to partially melt and
bond the fibers at this location together. The bonding roll 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 166, the web may
wrap the bonding roll 160 as shown in FIG. 32, or it may wrap the
female roll 104.
[0211] There are a number of variations of the roll configurations
in the bonding step. The surface of the bonding roll 160 may be
substantially smooth. Alternatively, as shown in FIGS. 32 and 35C,
it can have a plurality of discrete, spaced-apart bonding elements
162 protruding from its surface. The portions of the surface 124 of
the female roll 104 that are located outside of the recesses 114 in
the female roll 104 may also be substantially smooth, or they may
have a plurality of discrete, spaced-apart bonding elements 164
protruding from the surface 124. The bonding elements 164 on the
surface 124 of the female roll 104 may be discrete, spaced-apart
bonding elements 164 as shown in FIG. 35A, or they may be
continuous bonding elements 164 as shown in FIG. 35B.
[0212] In those cases in which the surface of the bonding roll 160
is substantially smooth, the base bond sites 168 may be at least
substantially continuous and may substantially or completely
surround the deformations in the web 30. FIG. 33A shows a web
having continuous base bond sites 168. FIG. 33B is a cross-section
of the web shown in FIG. 33A.
[0213] As shown in FIG. 34, in those cases in which the bonding
roll 160 or the female roll 104 have a plurality of discrete,
spaced-apart bonding elements 162 and 164, respectively, protruding
from their surfaces, the bonding elements will only bond discrete,
spaced-apart regions of the web 30 in the undeformed first region
40 outside of the bases 50 of the protrusions 32. In such case, the
base bonds 168 may be located in at least two discrete portions of
the first region 40 which are adjacent to and lie outside of at
least some of the deformations. In other words, in such cases there
may be at least two base bond sites 168 for a given
deformation.
[0214] c) Tip and Base Bonding.
[0215] In another embodiment, the deformed nonwoven material 30 can
be both tip and base bonded. This can be done in a process that is
a combination of the processes shown in FIGS. 28 and 32.
[0216] FIG. 40 shows one embodiment of an apparatus 100 for
carrying out such a process. The rolls 102, 104, and 150 comprise
the tip bonding portion of the apparatus, which is similar to the
apparatus shown in FIG. 28. FIG. 40 differs in that the precursor
web 30' is shown as being fed into the deforming nip 106 from the
right side in FIG. 40, instead of the left side, and the deformed
web 30 wraps around male roll 102 instead of bonding roll 150 after
it leaves the deforming nip 106. Therefore, the description of this
portion of the apparatus will incorporate the above description of
the apparatus shown in FIG. 28, and will not be repeated in its
entirety herein.
[0217] The apparatus shown in FIG. 40 further comprises a second
female roll 104A and a base bonding roll 160. The male roll 102,
the second female roll 104A, and the base bonding roll 160 comprise
the base bonding portion of the apparatus, which is similar to the
apparatus shown in FIG. 32. FIG. 40 differs in that the deformed
bonded web 30 is shown as wrapping around the second female roll
104A as it leaves the apparatus in FIG. 40, instead of wrapping
around the base bonding roll 160. Therefore, the description of
this portion of the apparatus will incorporate the above
description of the apparatus shown in FIG. 32, and will not be
repeated in its entirety herein.
[0218] As shown in FIG. 40, the precursor web 30' is fed into the
deforming nip 106 between first forming roll 102 and second forming
roll 104. After leaving the deforming nip 106, the deformed web 30
is wrapped partially around the first forming roll, male roll 102.
While the web 30 is still in contact with the male roll 102, it
passes through a second nip 156 between male roll 102 and the
additional bonding roll 150. The additional bonding roll 150 can
compress the fibers at the distal ends 54 of the protrusions 32
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. 29, this produces a protrusion
32 in which the deformed nonwoven material 30 is bonded together at
the tops (or distal ends 54) of the protrusions 32. The deformed
tip bonded web 30 then passes between male roll 102 and second
female roll 104A. After that, the deformed tip bonded web 30 is
wrapped partially around the second female roll 104A. While the web
30 is still in contact with the second female roll 104A, it passes
through a second nip 166 between the second female roll 104A and
the additional bonding roll 160. The additional bonding roll 160
can compress the fibers in the undeformed first region 40 outside
of the bases 50 of the protrusions 32 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 168 which may be
continuous as shown in FIG. 33A, or discrete as shown in FIG.
34.
[0219] 2. Bonding the Nonwoven Materials to an Additional
Layer.
[0220] In other embodiments, a deformed nonwoven material can be
bonded to another material to form a composite web or sheet. The
term "sheet" will be used herein to refer to a portion (e.g., a
discrete length) of a web that has been cut into an individual
piece from the web, typically as a final step in a manufacturing
process. Therefore, if a property is described herein as being
present in the composite web, it will also be present in the
composite sheet. The components of the composite sheet may be
described as being "partially bonded" together. By this it is meant
that the components are bonded together at certain locations on
their surfaces, and are not bonded together over their entire
surfaces. The components of the composite sheet in any of the
embodiments described herein can be bonded together using any
suitable type of bonding process including, but not limited to
ultrasonics, adhesives, and heat and/or pressure, or combinations
of the same.
[0221] a) Tip Bonding.
[0222] In some embodiments, a deformed nonwoven material can be
bonded to another material to form a composite web or sheet by
bonding the layers together at the tops or distal ends 54 of the
protrusions 32 of the deformed nonwoven material.
[0223] FIG. 30 shows one embodiment of an apparatus 100 similar to
that shown in FIG. 28. The apparatus shown in FIG. 30 deforms the
nonwoven material and also includes an additional bonding roll 150.
In this embodiment, the bonding roll 150 is used for bonding the
deformed nonwoven material 30 to an additional layer 158 at the
distal ends 54 of the protrusions 32 in the deformed nonwoven
material 30. As shown in FIG. 30, the additional bonding roll 150
is located downstream of the first nip, deforming nip 106. The
bonding roll 150 can have any suitable surface configuration. In
some embodiments, the surface of the bonding roll 150 may be
substantially smooth. In other cases, the bonding roll 150 may have
a plurality of bonding elements 154 protruding from the surface of
the bonding roll 150. The second nip 156 is formed between the male
roll 102 and the bonding roll 150.
[0224] The nonwoven web with deformations therein, which comprises
a first web 30, and a second nonwoven web 170 are fed into the
second nip 156. Vacuum, hold down belts, or some other mechanism
could be used to keep the deformed web 30 seated on the first
forming roll 102 as it is transferred to the second nip 156. The
nonwoven web 30 with deformations therein can be a single layer
nonwoven web or a dual or multiple layer nonwoven web. The second
nonwoven web 170 can comprise any of the types of nonwoven webs
specified as being suitable for use as precursor webs for the
nonwoven material. The second nonwoven web 170, however, need not
be deformed as in the case of the first web 30, and thus may be
substantially planar. In some embodiments, at least one of the
first web 30 and second web 170 comprises a spunbond nonwoven which
has discrete bond sites 46 therein. The first web 30 can have any
of the characteristics of the deformed nonwoven materials described
herein (e.g., one or more layers, bulbous protrusions, bond sites,
areas with different fiber concentration, etc.). The bonding roll
150 can have any other properties (heated or unheated) and manner
of bonding (compression and/or melting) in the tip bonding process
described above. In addition, adhesive may be applied to the second
nonwoven web 170 prior to the second nip 156 in order to facilitate
bonding.
[0225] The second nip 156 bonds at least a portion of the distal
ends 54 of the protrusions in the first web 30 to the second web
170 to form a tip-bonded composite web 172 in which the first and
second webs are bonded together at inter-web bond sites 174. The
first web 30 has a first region 40 that can be considered to have
an X-direction orientation (which may be in the machine direction),
a Y-direction orientation (which may be in the cross-machine
direction), and the protrusions 32 extend outward therefrom in the
Z-direction. The inter-web bond sites 174 are spaced apart in the
X-direction and the Y-direction so that the composite web 172 has
unbonded regions between the inter-web bond sites 174 in all
directions. This differs from corrugated materials which typically
contact and are bonded to a second layer along the length of the
corrugations rather than at discrete bond sites.
[0226] The inter-web bond sites 174 comprise bonded portions of the
protrusions 32. In some embodiments, the bonded portions 174 of the
protrusions 32 may comprise fibers that are more densely packed
than the fibers in the first region 40 of the first web or sheet
30. In some cases, at least portions of the fibers in the bonded
portions 174 of the protrusions 32 may be melted. In those cases in
which the surface of the bonding roll 150 is substantially smooth,
the inter-web bond sites 174 will be formed on substantially the
entire distal ends 54 of the protrusions 32 in the first web 30. In
those cases in which the bonding roll 150 has a plurality of
discrete, spaced-apart bonding elements 154 protruding from the
surface of the bonding roll 150, the bonding elements 154 will only
bond a portion of the distal ends 54 of the protrusions 32 in the
first web 30. In some cases, the inter-web bond sites 174 can be
formed in less than or equal to 25% of the area on the distal ends
54 of the protrusions 32.
[0227] Forming a composite sheet by bonding the deformed nonwoven
material 30 to another layer or material is believed to improve the
resiliency of the deformed web material 30 to compressive
forces.
[0228] b) Base Bonding.
[0229] In still other embodiments, the deformed nonwoven material
30 can be bonded to another material to form a composite sheet by
bonding the layers together at the base of the protrusions of the
deformed nonwoven material. The layers of the composite sheet can
be bonded together using any suitable type of bonding process
including, but not limited to ultrasonics, adhesives, and heat
and/or pressure, or combinations of the same.
[0230] FIG. 35 shows one embodiment of an apparatus 100 for
deforming the nonwoven material which includes an additional
bonding roll 160 for bonding the deformed nonwoven material 30 to
an additional layer outside the base 50 of the protrusions 32 of
the deformed nonwoven material 30. As shown in FIG. 35, the
additional bonding roll 160 is located downstream of the first nip
106. The second nip 166 is formed between the female roll 104 and
the bonding roll 160.
[0231] The nonwoven web 30 with deformations therein, which
comprises a first sheet and a second nonwoven web 180 are fed into
the second nip 166. Vacuum, hold down belts, or some other
mechanism could be used to keep the deformed web 30 seated on the
female roll 104 as it is transferred to the second nip 166. The
nonwoven web 30 with deformations therein can be a single layer
nonwoven web or a dual or multiple layer nonwoven web. The second
nonwoven web 180 can comprise any of the types of nonwoven webs
specified as being suitable for use as precursor webs for the
nonwoven material and can have any of the properties of the second
nonwoven web 170 in the tip bonding process (of the deformed
nonwoven to an additional layer) described above.
[0232] The second nip 166 bonds at least a portion of the deformed
nonwoven web 30 outside the base 50 of the protrusions 32 in the
first web 30 to the second web 180 to form a base-bonded composite
web or sheet 182 in which the first and second webs are bonded
together at inter-web bond sites 184. As in the case of the tip
bonding process, the inter-web bond sites 184 are spaced apart in
the X-direction and the Y-direction.
[0233] The inter-web bond sites 184 comprise bonded portions at the
base 50 of the protrusions 32 outside of the deformations and in
the first region 40 of the first web 30 to form a base-bonded
composite web 182. In some embodiments, the base bonded portions
184 may comprise fibers that are more densely packed than the
fibers in the first region 40 of the first web 30. In some cases,
at least portions of the fibers in the base bonded portions 184 of
the first web 30 may be melted.
[0234] There are a number of variations of the roll configurations
in the bonding step. The surface of the bonding roll 160 may be
substantially smooth. Alternatively, as shown in FIGS. 35 and 35C,
it can have a plurality of discrete, spaced-apart bonding elements
162 protruding from its surface. The portions of the surface 124 of
the female roll 104 that are located outside of the recesses 114 in
the female roll 104 may also be substantially smooth, or they may
have a plurality of discrete, spaced-apart bonding elements 164
protruding from the surface 124. The bonding elements 164 on the
surface 124 of the female roll 104 may be discrete, spaced-apart
bonding elements 164 as shown in FIG. 35A, or they may be
continuous bonding elements 164 as shown in FIG. 35B.
[0235] In those cases in which the surface of the bonding roll 160
is substantially smooth, the inter-web bond sites 184 may be at
least substantially continuous and may substantially or completely
surround the deformations in the first web 30 similar to the base
bond sites 168 shown in FIG. 33A.
[0236] In those cases in which the bonding roll 160 or the female
roll 104 have a plurality of discrete, spaced-apart bonding
elements 162 and 164, respectively, protruding from their surfaces,
the bonding elements will only bond discrete, spaced-apart regions
of the first web 30 (that lie outside of the deformations) to the
second web 180. In such cases, the inter-web bonds 184 may be
located in at least two discrete portions of the first region 40
which are adjacent to and lie outside of at least some of the
deformations. Thus, in such cases there may be at least two
inter-web base bond sites 184 for a given deformation similar to
the base bond sites 168 shown in FIG. 34.
[0237] c) Tip and Base Bonding.
[0238] In other embodiments, the deformed nonwoven material 30 can
be tip bonded or base bonded as described above, and then also
bonded to another material to form a composite web or sheet.
[0239] FIG. 41 shows one embodiment of an apparatus 100 for
carrying out a tip bonding process in which the tip bonded deformed
nonwoven web 30 is then base bonded to another material to form a
composite web or sheet. The apparatus 100 shown in FIG. 41 is
similar to the apparatus shown in FIG. 40. FIG. 41 differs from the
apparatus shown in FIG. 40 in that an additional layer 180 is fed
into the apparatus and is bonded to the deformed nonwoven material
30 outside the base 50 of the protrusions 32 of the deformed
nonwoven material 30. This aspect of the apparatus shown in FIG. 41
(feeding an additional layer for base bonding) is similar to that
shown in FIG. 35. Therefore, the description of the apparatus shown
in FIG. 41 will incorporate the above descriptions of the
apparatuses shown in FIGS. 35 and 40, and will not be repeated in
its entirety herein.
[0240] As shown in FIG. 41, the precursor web 30' is fed into the
deforming nip 106 between first forming roll 102 and second forming
roll 104. After leaving the deforming nip 106, the deformed web 30
is wrapped partially around the first forming roll, male roll 102.
While the web 30 is still in contact with the male roll 102, it
passes through a second nip 156 between male roll 102 and the
additional bonding roll 150. The additional bonding roll 150 can
compress the fibers at the distal ends 54 of the protrusions 32
sufficient to partially melt and bond the fibers at this location
together. As shown in FIG. 29, this produces a protrusion 32 in
which the deformed nonwoven material 30 is bonded together at the
tops (or distal ends 54) of the protrusions 32.
[0241] The deformed tip bonded web 30 then passes between male roll
102 and second female roll 104A. After that, the deformed tip
bonded web 30 is wrapped partially around the second female roll
104A. While the web 30 is still in contact with the second female
roll 104A, it passes through a second nip 166 between the second
female roll 104A and the additional bonding roll 160. The second
nip 166 bonds at least a portion of the deformed nonwoven web 30
outside the base 50 of the protrusions 32 in the first web 30 the
second web 180 to form a base-bonded composite web or sheet 182 in
which the first and second webs are bonded together at inter-web
bond sites 184. The inter-web base bonds 184 may be continuous
similar to the base bonds 168 shown in FIG. 33A, or discrete
similar to the base bonds 168 shown in FIG. 34.
[0242] FIG. 42 shows one embodiment of an apparatus 100 for
carrying out a base bonding process in which the base bonded
deformed nonwoven web 30 is then tip bonded to another material to
form a composite web or sheet.
[0243] The rolls 102, 104, and 160 shown in FIG. 42 comprise the
base bonding portion of the apparatus, which is similar to the
apparatus shown in FIG. 32. FIG. 42 differs in that the precursor
web 30' is shown as being fed into the deforming nip 106 from the
right side, instead of the left side, and the deformed web 30 wraps
partially around female roll 102 instead of bonding roll 160 after
it leaves the deforming nip 106. Therefore, the description of this
portion of the apparatus will incorporate the above description of
the apparatus shown in FIG. 32, and will not be repeated in its
entirety herein.
[0244] The apparatus shown in FIG. 42 further comprises a second
male roll 102A and a tip bonding roll 150. The female roll 104, the
second male roll 102A, and the tip bonding roll 150 comprise the
tip bonding portion of the apparatus, which is similar to the
apparatus shown in FIG. 30. FIG. 42 differs in that the deformed
bonded web 30 is shown as wrapping around the second male roll 102A
as it leaves the apparatus in FIG. 42, instead of wrapping around
the tip bonding roll 150. Therefore, the description of this
portion of the apparatus will incorporate the above description of
the apparatus shown in FIG. 30, and will not be repeated in its
entirety herein.
[0245] As shown in FIG. 42, the precursor web 30' is fed into the
deforming nip 106 between first forming roll 102 and second forming
roll 104. After leaving the deforming nip 106, the deformed web 30
is wrapped partially around the second forming roll, female roll
104. While the web 30 is still in contact with the female roll 104,
it passes through a second nip 166 between female roll 104 and the
additional bonding roll 160 for base bonding the deformed nonwoven
material 30. The additional bonding roll 160 can compress the
fibers in the undeformed first region 40 outside of the bases 50 of
the protrusions 32 sufficient to partially melt and bond the fibers
at this location together. This will provide the base bonded web
with base bonds 168 which may be continuous similar to those shown
in FIG. 33A, or discrete similar to those shown in FIG. 34. The
deformed base bonded web 30 then passes between female roll 104 and
second male roll 102A. After that, the deformed base bonded web 30
is wrapped partially around the second male roll 102A. While the
web 30 is still in contact with the second male roll 102A, it
passes through a second nip 156 between the second male roll 102A
and the additional bonding roll 150.
[0246] At the second nip 156, an additional layer 170 is fed into
the apparatus and is bonded to the deformed nonwoven material 30 at
the tops (or distal ends 54) of the protrusions 32. This will form
a composite web or sheet 172 similar to that shown in FIG. 31
comprising a base bonded deformed web 30 that is tip bonded to a
second web 170.
V. Test Methods
[0247] A. Accelerated Compression Method. [0248] 1. Cut 10 samples
of the specimen to be tested and 11 pieces of a paper towel into a
3 inch.times.3 inch (7.6 cm.times.7.6 cm) square. [0249] 2. Measure
the caliper of each of the 10 specimens at 2.1 kPa and a dwell time
of 2 seconds using a Thwing-Albert ProGage Thickness Tester or
equivalent with a 50-60 millimeter diameter circular foot.
Alternatively, a pressure of 0.5 kPa can be used. Record the
pre-compression caliper to the nearest 0.01 mm. [0250] 3. Alternate
the layers of the specimens to be tested with the pieces of paper
towel, starting and ending with the paper towels. The choice of
paper towel does not matter and is present to prevent "nesting" of
the protrusions in the deformed samples. The samples should be
oriented so the edges of each of the specimens and each of the
paper towels are relatively aligned, and the protrusions in the
specimens are all oriented the same direction. [0251] 4. Place the
stack of samples into a 40.+-.2.degree. C. oven at 25.+-.3%
relative humidity and place a weight on top of the stack. The
weight must be larger than the foot of the thickness tester. To
simulate high pressures or low in-bag stack heights, apply 35 kPa
(e.g. 17.5 kg weight over a 70.times.70 mm area). To simulate low
pressures or high in-bag stack heights, apply 7.0 kPa (e.g. 3.4 kg
weight over a 70.times.70 mm area), 4.0 kPa (e.g., 1.9 kg weight
over a 70.times.70 mm area) of 1.0 kPa (e.g., 0.49 kg weight over a
70.times.70 mm area). [0252] 5. Leave the samples in the oven for
15 hours. After the time period has elapsed, remove the weight from
the samples and remove the samples from the oven. [0253] 6. Within
30 minutes of removing the samples from the oven, measure the
post-compression caliper as directed in step 2 above, making sure
to maintain the same order in which the pre-compression caliper was
recorded. Record the post-compression caliper of each of the 10
specimens to the nearest 0.01 mm. [0254] 7. Let the samples rest at
23.+-.2.degree. C. at 25.+-.3% relative humidity for 24 hours
without any weight on them. [0255] 8. After 24 hours, measure the
post-recovery caliper of each of the 10 specimens as directed in
step 2 above, making sure to maintain the same order in which the
pre-compression and post-compression calipers were recorded. Record
the post-recovery caliper of each of the 10 specimens to the
nearest 0.01 mm. Calculate the amount of caliper recovery by
subtracting the post-compression caliper from the post-recovery
caliper and record to the nearest 0.01 mm. [0256] 9. If desired, an
average of the 10 specimens can be calculated for the
pre-compression, post-compression and post-recovery calipers.
[0257] B. Tensile Method
[0258] The MD and CD tensile properties are measured using World
Strategic Partners (WSP) (harmonization of the two nonwovens
organizations of INDA (North American based) and EDANA (Europe
based)) Tensile Method 110.4 (05) Option B, with a 50 mm sample
width, 60 mm gauge length, and 60 mm/min rate of extension. Note
that the gauge length, rate of extension and resultant strain rate
are from different from that specified within the method.
[0259] C. Surface Texture Characterization Method
[0260] The microscale surface texture of male elements is analyzed
using a 3D Laser Scanning Confocal Microscope (suitable 3D Laser
Scanning Confocal Microscope is the Keyence VK-X210, commercially
available from Keyence Corporation of America, Itasca, Ill., USA).
The microscope is interfaced with a computer running a measuring,
control, and surface texture analysis software (suitable software
is Keyence VK Viewer version 2.2.0.0 and Keyence VK Analyzer
version 3.3.0.0, commercially available from Keyence Corporation of
America, Itasca, Ill., USA).
[0261] The 3D surface Laser Scanning Confocal Microscope measures
the surface heights of a specimen, and produces a map of surface
height (z-directional or z-axis) versus displacement in the x-y
plane. The surface map is then analyzed according to ISO
25178-2:2012, from which the areal surface texture parameters Sq,
Sxp, Str and Vmp are calculated. These parameters describe key
characteristics of the male element surface.
[0262] Using a 20.times. objective lens, a 1.0.times. zoom level
and a 0.50 .mu.m pitch (Z-step size), the microscope is programmed
to collect a surface height image with a field of view of at least
500 .mu.m.times.700 .mu.m with an x-y pixel resolution of
approximately 0.7 microns (.mu.m)/pixel. If a larger field of view
is required, multiple scans, maintaining the x-y resolution, over
the surface can be collected and stitched together into a single
image for analysis. The height resolution is set at 0.1 nm/digit,
over a sufficient height range to capture all peaks and valleys
within the field of view.
[0263] Calibrate the instrument according to the manufacturer's
specifications.
[0264] Place the male element specimen on the stage beneath the
objective lens. Collect a surface height image (z-direction) of the
specimen by following the instrument manufacturer's recommended
measurement procedures, which may include using the following
settings to minimize noise and maximize the quality of the surface
data: Real Peak Detection, single/double scan, surface profile
mode, standard area, high-accuracy quality; laser intensity
(Brightness and ND filter) set using auto gain. Save the surface
height image.
[0265] Open the surface height image in the surface texture
analysis software. ISO 25178-2:2012 describes a recommended
filtration process, accordingly the following filtering procedure
is performed on each image: 1) a Gaussian low pass S-filter with a
nesting index (cut-off) of 2.5 .mu.m; 2) an F-operation of plane
tilt (auto) correction; and 3) a Gaussian high pass L-filter with a
nesting index (cut-off) of 0.25 mm. Both Gaussian filters are run
utilizing end effect correction. This filtering procedure produces
the SL surface from which the areal surface texture parameters will
be calculated.
[0266] Select the entire field of view for measurement, and
calculate the areal surface roughness parameters on the SL
Surface.
[0267] The surface texture parameters Sq, Sxp, Str and Vmp are
described in ISO 25178-2:2012. Sq is the root mean square of the
profile heights of the roughness surface. The units of Sq are
.mu.m. The parameters Sxp and Vmp are derived from the Areal
Material Ratio (Abbott-Firestone) curve described in the ISO
13565-2:1996 standard extrapolated to surfaces, it is the
cumulative curve of the surface height distribution histogram
versus the range of surface heights. A material ratio is the ratio,
given as a %, of the intersecting area of a plane passing through
the surface at a given height to the cross sectional area of the
evaluation region. The Peak Extreme Height, Sxp, is a measure of
the difference in heights on the surface from the areal material
ratio value of 2.5% (highest peaks, excluding outliers) to the
areal material ratio value of 50% (the mean plane). The units of
Sxp are .mu.m. The Peak Material Volume, Vmp, is the actual volume
of material comprising the surface from the height corresponding to
a material ratio value of 10% to the highest peak (material ratio
of 0%). The units of Vmp are mL/m.sup.2. The Texture Aspect Ratio,
Str, is a measure of the spatial isotropy or directionality of the
surface texture. Str is a spatial parameter which involves the use
of the mathematical technique of the autocorrelation function. The
Str parameter has a value range between 0 and 1, and is unitless.
An isotropic surface will have Str close to 1, while a strongly
anisotropic surface will have Str close to 0. Str is calculated
using a thresholding value of s=0.2. If a Str value is unable to be
calculated, rotate the specimen by 30 degrees, rescan and reanalyze
the surface.
[0268] Scan and analyze the surface textures of three replicate
male elements. Average together the three Sq values and report to
the nearest 0.01 .mu.m. Average together the three S.times.p values
and report to the nearest 0.01 .mu.m. Average together the three
Vmp values and report to the nearest 0.01 mL/m.sup.2. Average
together the three Str values and report to the nearest 0.01
units.
[0269] D. Light Transmission.
[0270] The feature and land area light transmission method measures
the average amount of light transmitted through specific regions of
a specimen. A calibrated light transmission image is obtained using
a flatbed scanner. A binary mask is generated using a corresponding
surface topography image that is thresheld at a given height to
separate discrete feature regions from the surrounding land area.
The binary mask is then registered to the light transmission image,
and used to isolate the discrete features from the land area in the
light transmission image. This enables the average light
transmission value for each region to be calculated.
[0271] Sample Preparation--Topsheet/Underlying Layer Laminate
[0272] Tape the absorbent article to a rigid flat surface in a
planar configuration with the body-facing surface up. Any leg
elastics may be cut to facilitate laying the article flat. The
entire topsheet/underlying layer (e.g. acquisition layer) laminate
specimen is then carefully removed from the article. A scalpel
and/or cryogenic spray (such as Cyto-Freeze, Control Company,
Houston Tex. USA) can be used to remove the specimen from
additional underlying layers, if necessary, to avoid any
longitudinal and lateral extension of the specimen. The
topsheet/underlying layer laminate specimen should be handled only
with forceps around its peripheral edge. If the topsheet is not
joined to an underlying layer, carefully remove only the topsheet
layer as the specimen.
[0273] Identify a 40 mm.times.40 mm square region centered at, with
the sides parallel to, the longitudinal and lateral centerlines of
the specimen. Create registration marks on the specimen surface by
using a black marker to make a small dot in the four corners of the
identified 40 mm.times.40 mm square analysis region. Similarly,
identify and mark a second and a third 40 mm.times.40 mm square
analysis region. The second centered along the longitudinal
centerline 50 mm inboard from the leading edge of the
topsheet/underlying layer laminate, and the third centered along
the longitudinal centerline 50 mm inboard from the trailing edge of
the topsheet/underlying layer laminate. Depending on the length of
the specimen the identified regions may overlap each other, if so,
follow the procedure as described and analyze the entirety of each
of the three regions. If the topsheet is not joined to an
underlying layer, identify and mark the three 40 mm.times.40 mm
analysis regions in like fashion, except use the leading and
trailing edges of the topsheet to identify the location of the
second and third analysis regions.
[0274] Five replicate topsheet/underlying layer laminate specimens
are obtained from five substantially similar absorbent articles are
similarly prepared for analysis. Precondition the specimens at
about 23.degree. C..+-.2 C..degree. and about 50%.+-.2% relative
humidity for 2 hours prior to testing.
[0275] Light Transmission Image
[0276] The color difference (delta E*) measurement is based on the
CIE L* a* b* color system (CIELAB). A flatbed scanner capable of
scanning a minimum of 24 bit color at 800 dpi and has manual
control of color management (a suitable scanner is an Epson
Perfection V750 Pro from Epson America Inc., Long Beach Calif. USA)
is used to acquire images. The scanner is interfaced with a
computer running color management software (suitable color
management software is MonacoEZColor available from X-Rite Grand
Rapids, Mich. USA). The scanner is calibrated against a color
transparency target and corresponding reference file compliant with
ANSI method IT8.7/1-1993 using the color management software to
construct a calibrated color profile. The resulting calibrated
scanner profile is used to color correct an image from a test
specimen within an image analysis program that supports sampling in
CIE L* a* b* (a suitable program is Photoshop S4 available from
Adobe Systems Inc., San Jose, Calif. USA). All testing is performed
in a conditioned room maintained at about 23.+-.2.degree. C. and
about 50.+-.2% relative humidity.
[0277] Turn on the scanner for 30 minutes prior to calibration.
Deselect any automatic color correction or color management options
that may be included in the scanner software. If the automatic
color management cannot be disabled, the scanner is not appropriate
for this application. Place the IT8 target face down onto the
scanner glass, close the scanner lid, acquire an image at 200 dpi
and 24 bit color and remove the IT8 target. Open the image file on
the computer with the color management software. Follow the
recommended steps within the color management software to create
and export a calibrated color profile. These steps may include,
ensuring that the scanned image is oriented and cropped correctly.
The calibrated color profile must be compatible with the image
analysis program. The color management software uses the acquired
image to compare with the included reference file to create and
export the calibrated color profile. After the profile is created
the scan resolution (dpi) for test specimens can be changed, but
all other settings must be kept constant while imaging
specimens.
[0278] Open the scanner lid and place the specimen flat against the
scanner glass with the skin facing surface facing the glass.
Acquire and import a scan of the 40 mm.times.40 mm marked region of
the specimen into the image analysis software at 24 bit color and
at 800 dpi in transparency mode. Transparency mode illuminates the
specimen from one side with the sensor capturing the image from the
opposite side. Ensuring that each of the four registration marks
are located in the corners of the scanned image. Assign the
calibrated color profile to the image and change the color space
mode to L*a*b* Color corresponding to the CIE L* a* b* standard.
This produces a color corrected image for analysis. Save this color
corrected image in an uncompressed format, such as a TIFF file.
[0279] Feature Area and Land Area Mask
[0280] The boundaries of the discrete feature areas and land area
are identified by thresholding a 3D surface topography image at a
specified height to generate a binary image, separating discrete
feature areas from the surrounding land area. This binary image
will then be used as a mask on the corresponding light transmission
image to measure the average Light Transmission Values of the
discrete feature areas separately from the average Light
Transmission Values of the surrounding land area.
[0281] The 3D surface topography image is obtained using an optical
3D surface topography measurement system (a suitable optical 3D
surface topography measurement system is the GFM MikroCAD Premium
instrument commercially available from GFMesstechnik GmbH,
Teltow/Berlin, Germany). The system includes the following main
components: a) a Digital Light Processing (DLP) projector with
direct digital controlled micro-mirrors; b) a CCD camera with at
least a 1600.times.1200 pixel resolution; c) projection optics
adapted to a measuring area of at least 60 mm.times.45 mm; d)
recording optics adapted to a measuring area of 60 mm.times.45 mm;
e) a table tripod based on a small hard stone plate; f) a blue LED
light source; g) a measuring, control, and evaluation computer
running surface topography analysis software (suitable software is
ODSCAD software version 6.2 available from GFMesstechnik GmbH,
Teltow/Berlin, Germany); and h) calibration plates for lateral
(x-y) and vertical (z) calibration available from the vendor.
[0282] The optical 3D surface topography measurement system
measures the surface height of a specimen using the digital
micro-mirror pattern fringe projection technique. The result of the
analysis is a map of surface height (z-directional or z-axis)
versus displacement in the x-y plane. The system has a field of
view of 60.times.45 mm with an x-y pixel resolution of
approximately 40 microns. The height resolution is set at 0.5
micron/count, with a height range of +/-15 mm. All testing is
performed in a conditioned room maintained at about 23.+-.2.degree.
C. and about 50.+-.2% relative humidity.
[0283] Calibrate the instrument according to manufacturer's
specifications using the calibration plates for lateral (x-y axis)
and vertical (z axis) available from the vendor.
[0284] Place specimen on the table beneath the camera. Center the
marked 40 mm.times.40 mm analysis region of the specimen within the
camera field of view, so that only the specimen surface is visible
in the image. Place a steel frame (100 mm square, 1.5 mm thick with
an opening 70 mm square) on the sample to ensure the specimen lays
flat with minimal wrinkles, and still allows for an unobstructed
access to the surface area being scanned.
[0285] Collect a height image (Z-direction) of the specimen by
following the instrument manufacturer's recommended measurement
procedures, which may include, focusing the measurement system and
performing a brightness adjustment. No pre-filtering options should
be utilized. Save the collected height image file.
[0286] Load the height image into the surface analysis portion of
the software. The following filtering procedure is then performed
on each image: 1) remove invalid points; 2) a 3.times.3 pixel
median filter to remove noise; 4) an automatic planar alignment to
remove form; and 3) a Gaussian high pass filter with a cut-off
wavelength of 10 mm to filter out large scale waviness in the
sample. Crop the image to the 40 mm.times.40 mm square area
identified by the registration marks, so that each of the four
registration marks are located in the four corners of the cropped
image.
[0287] Determination of the thresholding height level utilizes the
Areal Material Ratio (Abbott-Firestone) curve, described in the ISO
13565-2:1996 standard extrapolated to surfaces. It is the
cumulative curve of the surface height distribution histogram
versus the range of surface heights. A material ratio is the ratio,
given as a %, of the intersecting area of a plane passing through
the surface at a given height (cutting depth) to the cross
sectional area of the evaluation region. If the specimen contains
discrete features which are depressions oriented downward relative
to the body facing surface or contains apertures, threshold the
surface topography image at a cutting depth where the material
ratio is 75%. A material ratio of 75% separates the deep valleys
from the land area region. If the specimen contains discrete
features which are protrusions or tufts oriented upward, threshold
the surface topography image at a cutting depth where the material
ratio is 25%. A material ratio of 25% separates the protruding
peaks from the land area region. By thresholding at the levels
described above, a binary mask image is produced with the discrete
feature areas assigned one value, and the surrounding land area
assigned a different value. For example, the discrete feature areas
could appear black, and the surrounding land area could appear
white. Save this binary mask image in an uncompressed format, such
as a TIFF file.
[0288] Analysis of Light Transmission Image
[0289] Open both the color corrected light transmission image and
the corresponding binary mask image in the image analysis software.
To analyze the specimen light transmission image, first separate
the L*, a* and b* channels, and select only the L* channel for
analysis. The L* channel represents the "Lightness" of the image
and has values that range from 0-100. Register the light
transmission image and the binary mask image to each other so that
the corresponding registration marks are aligned. Use the mask to
remove the land area from the light transmission image, and
calculate the average L* value (Light Transmission Value) for the
remaining discrete features. Record this value as the Feature Light
Transmission Value to the nearest 0.1 units. Then use the binary
mask to remove the discrete features from the light transmission
image, and calculate an average L* value (Light Transmission Value)
for the remaining surrounding land area. Record this value as the
Land Area Light Transmission Value to the nearest 0.1 units. Repeat
this procedure for the other two regions on the specimen. Calculate
the difference between the Feature Light Transmission Value and the
Land Area Light Transmission Value for each of the three analyzed
regions on a single specimen. Compare the three differences and
keep the Feature Light Transmission Value and Land Area Light
Transmission Value from the 40 mm.times.40 mm analysis region with
the highest difference and discard the values from the other two
regions. In like fashion repeat this procedure on all of the
replicate specimens. Calculate and report the average of the five
individual Feature Light Transmission Values and Land Area Light
Transmission Values to the nearest 0.1 units.
VI. Examples
Comparative Example 1
[0290] In Comparative Example 1, the material is a composite of two
materials glued together using H.B. Fuller of St. Paul, Minn.,
U.S.A. D3166ZP hot melt adhesive applied in a spiral pattern at a 1
gsm add on level. The composite material is processed through a nip
formed by one of The Procter & Gamble Company's SELF rolls and
a ring roll as described in U.S. Pat. No. 7,410,683 B2, Curro, et
al., at 25 feet/minute (fpm) (7.6 meters per minute) and 0.135''
(3.43 mm) DOE. The material layer in contact with the SELF roll is
a 20 gsm spunbond nonwoven produced by Fitesa of Simpsonville,
S.C., U.S.A. Such a material is described in Fitesa's U.S. patent
application Ser. No. 14/206,699 entitled "Extensible Nonwoven
Fabric" and is comprised of 2.5 denier fibers comprising a blend of
PP and PE The material layer in contact with the ring roll is a 43
gsm spunbond nonwoven produced by Reicofil of Troisdorf, Germany,
comprised of 7 denier co-PET/PET tipped-trilobal bicomponent
fibers.
Example 1
Single Layer
[0291] In Example 1, the material is a 50 grams/m.sup.2 (gsm) PE/PP
sheath/core bicomponent spunbond nonwoven from Fitesa. It is
processed at 25 fpm (7.6 meters per minute) speed at 0.155 inch
(3.94 mm) depth of engagement (DOE) through male/female tooling
(forming members). The teeth on the male tool have a rounded
diamond shape like that shown in FIG. 21, with vertical sidewalls
and a radiused or rounded edge at the transition between the top
and the sidewalls of the male element. The teeth are 0.186 inch
(4.72 mm) long and 0.125 inch (3.18 mm) wide with a CD spacing of
0.150 inch (3.81 mm) and an MD spacing of 0.346 inch (8.79 mm). The
recesses in the mating female roll also have a rounded diamond
shape, similar to that of the male roll, with a clearance between
the rolls of 0.032-0.063 inch (0.813-1.6 mm), varying slightly
around the perimeter of the recess.
Example 2
Two Layers
[0292] In Example 2, the material is a composite of two materials
glued together using the same hot melt adhesive applied in a spiral
pattern as described in Comparative Example 1. It is processed
through the male/female tooling described in Example 1, at 800 feet
per minute (fpm) (24.4 meters per minute) and 0.155 inch (3.94 mm)
DOE. The material layer in contact with the male roll is the 20 gsm
spunbond nonwoven produced by Fitesa comprised of 2.5 denier fibers
with a blend of PP and PE described in Comparative Example 1. The
material layer in contact with the female roll is a 60 gsm
through-air bonded carded nonwoven produced by Beijing Dayuan
Non-Woven Fabric Co, LTD of Beijing, China, comprised of 5 denier
PE/PET sheath/core bicomponent fibers.
Example 3
Two Layers
[0293] In Example 3, the material is a composite of two materials
glued together using the same hot melt adhesive applied in a spiral
pattern as described in Comparative Example 1. It is processed
through the male/female tooling described in Example 1, at 800 fpm
and 0.155 inch (3.94 mm) DOE. The material layer in contact with
the male roll is a 20 gsm spunbond nonwoven produced by Fitesa
comprised of 2.5 denier fibers with a blend of PP and PE described
in Example 2. The material layer in contact with the female roll is
an 86 gsm spunbond nonwoven produced by Reicofil comprised of 7
denier co-PET/PET tipped-trilobal bicomponent fibers.
[0294] The samples are compressed for 15 hours according to the
Accelerated Compression Method, with a 3.4 kg weight (7 kPa). The
pre-compression caliper and the post-compression caliper of the
samples are measured following the Accelerated Compression Method
under 2.1 kPa pressure. The dimensions of the protrusions and
openings are measured using a microscope at 20.times.
magnification. The exterior dimensions of the cap are measured from
a perspective view with the protrusions facing up, like that shown
in FIG. 5. The protrusion depth and the interior cap width is
measured from the cross-section of the material like that shown in
FIG. 11.
TABLE-US-00002 TABLE 2 Material Examples Ratio of Cap Base Cap
width- Measured Opening Base Width- Cap Cap Interior First Layer
Second Layer Before or After Caliper at Protrusion Width Opening
Interior Width- Length- to Base (Contacts (Contacts Compression 2.1
kPa Depth (W.sub.0) Length (W.sub.I) Exterior Exterior Opening
Example Male Tool) Female Tool) (7 kPa) (mm) (mm) (mm) (mm) (mm)
(mm) (mm) Width Comp. 20 gsm 43 gsm co- Before 1.2 1.1 0.5 4.7
<0.1* 1.5 4.6 -- Ex. 1 Spunbond PET/PET Compression (Tuft)
(Tuft) (Tuft) (Tuft) PE/PP Blend Spunbond After 0.7 0.3 0* 4.7 0*
0.7 4.0 -- Compression (opening (opening was was closed) closed)
Ex. 1 50 gsm None Before 0.48 1.3 1.5 3.3 1.7 2.4 4.2 1.1 PE/PP
Bico Compression Spunbond After 0.39 0.4 1.7 3.0 2.1 2.9 4.3 1.2
Compression Ex. 2 20 gsm 60 gsm PET Before 1.6 1.9 1.9 3.5 2.4 3.2
4.5 1.3 Spunbond Carded Compression PE/PP Blend Through-air After
0.88 0.5 1.6 3.3 1.8 2.7 4.4 1.1 Bonded Compression Ex. 3 20 gsm 86
gsm co- Before 2.0 1.9 1.8 3.8 2.2 3.8 4.8 1.2 Spunbond PET/PET
Compression PE/PP Blend Spunbond After 1.3 0.7 1.5 3.6 2.5 3.7 5.2
1.7 Compression *Difficult to measure because measurement was so
small
Example 4
Light Transmission Differences
[0295] FIGS. 37-40 show images of several nonwoven topsheets that
have been formed by different processes. Each has discrete features
that are formed into the materials.
[0296] FIG. 37 shows a nonwoven material 30 as described herein
shown with the base openings 44 facing upward (which appear as
depressions). The nonwoven material 30 comprises two layers that
are joined together to form a topsheet and underlying acquisition
layer. The layers comprise a 25 gsm polyethylene/polypropylene
bicomponent fiber topsheet layer and a 43 gsm spunbond PET
acquisition layer, glued together with 1 gsm spiral glue pattern
that have been run through the deformation process described
herein. The nonwoven material 30 comprises a generally planar first
region 40 and a plurality of discrete integral second regions 42
that comprise spaced apart deformations (the depressions) in the
nonwoven material. The first region 40 may form a continuous
inter-connected network region wherein portions of the network
surround each of the (depressions) deformations.
[0297] The first region 40 has a first light transmission value and
the second regions 42 have a second transmission value. The light
transmission values are summarized in Table 3 below. The second
light transmission value in the deformations is at least about 5
units greater, alternatively at least about 9 units, alternatively
about 10 units greater, than the first light transmission value. In
this example, the fibers are not densified or melted together,
which could also result in a higher light transmission value. The
method of making the nonwoven web described herein creates that
difference by rearranging the fibers in the web, resulting in a
lower fiber concentration, and therefore a higher light
transmission value, in the bottom of the depressions. The
deformations/second regions 42 have a light transmission of less
than or equal to about 90 units, indicating the absence of a
through-hole in the bottom of the deformations. (For comparison,
FIG. 38 is a photograph of an apertured nonwoven material. An
aperture that is substantially clear of fibers has a light
transmission value of between 95-100 units).
[0298] The nonwoven material 30 described herein is unique in that
(like the topsheet shown in FIG. 38) it creates the "look" of an
aperture that has depth, making it appear absorbent and dry, but
without some of the softness negatives (technical and perceptual)
associated with some apertures. Due to the increase in translucency
in the deformation, placing a colored layer behind the nonwoven
material 30 could result in color showing through primarily in the
depression, high-lighting the depression and, in some cases, making
it appear to have even more depth.
[0299] FIG. 39 is a photograph of a currently marketed
Kimberly-Clark HUGGIES.RTM. diaper topsheet 190 which has discrete
portions or tufts 192 oriented upward. In this example, the light
transmission value in the discrete portions 192 is in the opposite
relationship to that of the nonwoven material in FIG. 37. The light
transmission value in the discrete portions 192 is at least about 5
units lower, and more typically is at least about 7 units lower,
than the light transmission value in the continuous land region
194.
TABLE-US-00003 TABLE 3 Light Transmission Value Delta Feature Land
Area (Feature Discrete Std Std Minus Land) Samples Feature Mean Dev
Mean Dev Mean Example 4 Depression 65.5 8.7 56.5 7.2 9.0 HUGGIES
.RTM. Tuft 51.9 5.5 59.3 7.9 -7.4 Apertured Aperture 97.8 0.16 60.8
9.0 37.0 topsheet
[0300] 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 "90.degree." is intended to mean "about
90.degree.".
[0301] It should be understood that every maximum numerical
limitation given throughout this specification includes every lower
numerical limitation, as if such lower numerical limitations were
expressly written herein. Every minimum numerical limitation given
throughout this specification will include every higher numerical
limitation, as if such higher numerical limitations were expressly
written herein. Every numerical range given throughout this
specification will include every narrower numerical range that
falls within such broader numerical range, as if such narrower
numerical ranges were all expressly written herein.
[0302] All documents cited in the Detailed Description of the
Invention are, in relevant part, incorporated herein by reference;
the citation of any document is not to be construed as an admission
that it is prior art with respect to the present invention. To the
extent that any meaning or definition of a term in this written
document conflicts with any meaning or definition of the term in a
document incorporated by reference, the meaning or definition
assigned to the term in this written document shall govern.
[0303] 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.
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