U.S. patent application number 10/324602 was filed with the patent office on 2004-06-24 for composite elastic material.
Invention is credited to Jordan, Joy, Matela, David Michael, Rolsten, Gina Kay, Schmidt, Richard John.
Application Number | 20040121683 10/324602 |
Document ID | / |
Family ID | 32593500 |
Filed Date | 2004-06-24 |
United States Patent
Application |
20040121683 |
Kind Code |
A1 |
Jordan, Joy ; et
al. |
June 24, 2004 |
Composite elastic material
Abstract
The present invention is directed to an elastic composite
material having an elastic layer having a first side and a second
side; at least one gatherable layer bonded to at least one of the
first side and second side of the elastic layer; and a fibrous
material entangled and intertwined with both the elastic layer and
the gatherable layer. The resulting elastic composite provides a
stretchable material which can conform to surfaces and has
desirable properties of the fibrous material entangle and
intertwined with both the elastic layer and the gatherable layer
and does not suffer from the loss of the fibrous material from the
stretchable substrate. The composite is usable in as bandages,
durable wipes, durable mops and personal care products, such as
diapers and feminine napkins. Also disclosed is a method for making
the composite.
Inventors: |
Jordan, Joy; (Marietta,
GA) ; Matela, David Michael; (Alpharetta, GA)
; Rolsten, Gina Kay; (Lawrenceville, GA) ;
Schmidt, Richard John; (Roswell, GA) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.
401 NORTH LAKE STREET
NEENAH
WI
54956
|
Family ID: |
32593500 |
Appl. No.: |
10/324602 |
Filed: |
December 20, 2002 |
Current U.S.
Class: |
442/182 ;
442/181; 442/268; 442/286; 442/304; 442/306; 442/319; 442/327;
442/328; 442/381; 442/394 |
Current CPC
Class: |
B32B 2535/00 20130101;
B32B 5/04 20130101; B32B 23/02 20130101; Y10T 442/659 20150401;
Y10T 442/3008 20150401; B32B 2555/00 20130101; Y10T 442/60
20150401; Y10T 442/40 20150401; B32B 5/26 20130101; Y10T 442/3707
20150401; Y10T 442/494 20150401; B32B 5/08 20130101; Y10T 442/674
20150401; B32B 25/14 20130101; Y10T 442/413 20150401; B32B 25/10
20130101; B32B 37/144 20130101; Y10T 442/3854 20150401; B32B
2307/51 20130101; Y10T 442/601 20150401; B32B 2038/0028 20130101;
D04H 1/498 20130101; Y10T 442/30 20150401; D04H 1/492 20130101 |
Class at
Publication: |
442/182 ;
442/181; 442/268; 442/286; 442/304; 442/306; 442/319; 442/327;
442/328; 442/381; 442/394 |
International
Class: |
D03D 017/00; D03D
015/08 |
Claims
We claim:
1. An elastic composite material comprising a. an elastic layer
having a first side and a second side; b. at least one gatherable
layer bonded to at least one of the first side and second side of
the elastic layer; and c. a fibrous material entangled with both
the elastic layer and the gatherable layer.
2. The elastic composite of claim 1, wherein the elastic layer is
selected from the group consisting of an elastomeric film, an
elastomeric nonwoven web, a plurality of substantially continuous
elastomeric filaments arranged in substantially parallel rows, and
a laminate of an elastomeric nonwoven web and a plurality of
substantially continuous elastomeric filaments arranged in
substantially parallel rows.
3. The elastic composite of claim 2, wherein there is a gatherable
layer bonded to both the first and second sides of the elastic
layer.
4. The elastic composite of claim 1, wherein the fibrous material
entangled with both the elastic layer and the gatherable layer
comprises an absorbent fiber, a non-absorbent fiber or a mixture
thereof.
5. The elastic composite of claim 4, wherein the fibrous material
entangled with both the elastic layer and the gatherable layer
comprises pulp.
6. The elastic composite of claim 5, wherein the gatherable layer
comprises a woven, knit or a nonwoven web.
7. The elastic composite of claim 6, wherein the gatherable layer
comprises a nonwoven web selected from the group consisting of a
spunbond nonwoven web, a meltblown nonwoven web, a bonded carded
web or a laminate of two or more of these webs.
8. The elastic composite of claim 7, wherein the gatherable layer
comprises a spunbond nonwoven web.
9. The elastic composite of claim 8, wherein the elastic layer is
selected from the group consisting of an elastomeric film, an
elastomeric nonwoven web, a plurality of substantially continuous
elastomeric filaments, and a laminate of an elastomeric nonwoven
web and a plurality of substantially continuous elastomeric
filaments.
10. The elastic composite of claim 9, wherein there is a gatherable
layer bonded to both the first and second sides of the elastic
layer.
11. The elastic composite of claim 10, wherein the elastic layer
comprises an elastomeric polyester, elastomeric polyurethane,
elastomeric polyamide, an elastomeric copolymers of ethylene and at
least one vinyl monomer, or elastomeric A-B-A' block copolymer
wherein A and A' comprise the same or different thermoplastic
polymer, and B comprises an elastomeric polymer block.
12. The elastic composite of claim 1, wherein the gatherable layer
comprises a woven, knit or a nonwoven web.
13. The elastic composite of claim 12, wherein the gatherable layer
comprises a nonwoven web selected from the group consisting of a
spunbond nonwoven web, a meltblown nonwoven web, a bonded carded
web or a laminate of two or more of these webs.
14. The elastic composite of claim 13, wherein the gatherable layer
comprises a spunbond nonwoven web.
15. The elastic composite of claim 2, wherein there is a gatherable
layer bonded to both the first and second sides of the elastic
layer.
16. The elastic composite of claim 2, wherein the elastic layer
comprises an elastomeric polyester, elastomeric polyurethane,
elastomeric polyamide, an elastomeric copolymers of ethylene and at
least one vinyl monomer, or an elastomeric A-B-A' block copolymer
wherein A and A' comprise the same or different thermoplastic
polymer, and B comprises an elastomeric polymer block.
17. The elastic composite of claim 16, wherein the elastic layer
comprises an elastomeric A-B-A' block copolymer wherein A and A'
comprise the same or different thermoplastic polymer, and B
comprises an elastomeric polymer block.
18. The elastic composite of claim 17, wherein the elastic layer
comprises a laminate of an elastomeric nonwoven web and a plurality
of substantially continuous elastomeric filaments arranged in
substantially parallel rows.
19. The elastic composite according to claim 1, further comprising
a cohesive layer is applied to the gatherable layer.
20. A personal care product comprising the elastic composite of
claim 1.
21. A wipe comprising the elastic composite of claim 1.
22. A bandage comprising the elastic composite of claim 1.
23. A mop comprising the elastic composite of claim 1.
24. A process of producing an elastic composite material comprising
an elastic layer having a first side and a second side; at least
one gatherable layer bonded to at least one of the first side and
second side of the elastic layer; and a fibrous material entangled
and intertwined with the elastic layer and the gatherable layer,
said process comprising a. providing the elastic layer; b.
providing the gatherable layer; c. applying a stretching force to
the elastic layer to form a stretched elastic layer having a first
side and a second side; d. bonding the gatherable layer to the
stretched elastic layer to at least the first side or the second
side of the elastic layer to form a stretch bonded laminate; e.
providing the fibrous material onto the gatherable layer of the
stretch bonded laminate; f. entangling the fibrous material into
the stretch bonded laminate; and g. relaxing the stretching
force.
25. The process of claim 24, wherein the entangling comprises
jetting a plurality of high pressure liquid streams towards the
material so that the material is intertwined with both the elastic
layer and the gatherable layer.
26. The process of claim 24, wherein a gatherable layer is bonded
to both the first side and the second side of the nonwoven web.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a composite elastic
material, uses of the composite elastic material and the method of
making the composite elastic material.
BACKGROUND OF THE INVENTION
[0002] Composites of elastic and nonelastic materials have been
made by bonding nonelastic materials to elastic materials in a
manner that allows the entire composite material to stretch or
elongate. These composites can be used in garment materials, pads,
diapers, training pants and other personal care products where
elasticity is needed.
[0003] In one such composite material, a nonelastic material is
joined, for example pattern bonded, to an elastic sheet while the
elastic sheet is in a stretched condition. These materials are
often referred to as "stretch-bonded laminates." When the elastic
sheet is relaxed, the nonelastic material gathers between the
locations where it is joined to the elastic sheet. The resulting
composite elastic material is stretchable to the extent that the
nonelastic material, gathered between the locations where the
nonelastic and elastic materials are joined, allows the elastic
sheet to elongate. An example of this type of composite material is
disclosed by, for example, U.S. Pat. No. 4,720,415 to Vander Wielen
et al. and U.S. Pat. No. 5,503,908 to Faass et al., both hereby
incorporated by reference in their entirety.
[0004] In another stretched-bonded laminate described in U.S. Pat.
No. 5,385,775, to Wright, which is hereby incorporated by reference
in its entirety, the elastic layer contains an anisotropic elastic
fibrous web having at least one layer of elastomeric meltblown
fibers and at least one layer of substantially parallel rows of
elastomeric filaments autogenously bonded to at least a portion of
the elastomeric meltblown fibers. This elastic fibrous web is
bonded to at least one gatherable layer joined at spaced apart
locations to the anisotropic elastic fibrous web, so that the
gatherable layer is gathered between the spaced-apart locations.
The stretch-bonded laminate described in this patent has improved
tenacity in one direction.
[0005] Hydraulic entangling is a process known in the art in which
a high pressure liquid (usually water) entangles fibers or
particles into a substrate. The entangling serves to "bond" or
immobilize the fibers or particles in the substrate. Such a process
and apparatus to accomplish the entanglement is described in U.S.
Pat. No. 3,485,706 to Evans, which is hereby incorporated by
reference in its entirety.
[0006] Further, it is known in the art to entangle nonelastic
fibers into elastic filaments or an elastic substrate. In U.S. Pat.
No. 4,775,579 to Hagy, which is hereby incorporated by reference in
its entirety, the entangled material is prepared by forming a first
layer of a web or net of an elastomeric material, stretching the
elastomeric material, placing a layer of a nonelastic material on
top of the web or net of the elastomeric material, subjecting the
two layers to a hydraulic entangling process step and releasing the
stretching to relax the elastomeric material. The resulting
composite material is said to be usable in bandages, but suffers
from the fact that the composite can be stretched to a point where
"destructive elongation" occurs, resulting in a material that will
no long recover, making unusable as a bandage material.
SUMMARY OF INVENTION
[0007] The present invention is directed to an elastic composite
material having an elastic layer having a first side and a second
side; at least one gatherable layer bonded to at least one of the
first side and second side of the elastic layer; and a fibrous
material entangled and intertwined with both the elastic layer and
the gatherable layer. The resulting elastic composite provides a
stretchable material which can conform to surfaces and has
desirable properties of the fibrous material entangled and
intertwined with both the elastic layer and the gatherable layer
and does not suffer from the loss of the fibrous material from the
stretchable substrate.
[0008] The elastic layer can be an elastomeric film, an elastomeric
nonwoven web, a plurality of substantially continuous elastomeric
filaments arranged in substantially parallel rows, or a laminate of
an elastomeric nonwoven web and a plurality of substantially
continuous elastomeric filaments arranged in substantially parallel
rows. In addition, a gatherable layer, which can be a woven or
nonwoven web, may be bonded to both sides of the elastic layer.
Desirably, the gatherable layer is bonded to the elastic layer at
spaced apart locations. The fibrous material entangled and
intertwined imparts desirable properties to the elastic composite,
such as, for example absorbency.
[0009] The present invention is also directed to a process of
producing an elastic composite material of the present invention.
The elastic composite may be prepared by a process including the
steps of:
[0010] a. providing the elastic layer;
[0011] b. providing the gatherable layer;
[0012] c. applying a stretching force to the elastic layer to form
a stretched elastic layer having a first side and a second
side;
[0013] d. bonding the gatherable layer to the stretched elastic
layer to at least the first side or the second side of the elastic
layer to form a stretch-bonded laminate;
[0014] e. providing the fibrous material onto the gatherable layer
of the stretch-bonded laminate;
[0015] f. entangling the fibrous material into the stretch bonded
laminate; and
[0016] g. relaxing the stretching force.
[0017] In the present invention, the entangling of the fibrous
material into the stretched-bonded laminate is desirable
accomplished through hydraulic entangling.
[0018] The elastic composite has many utilities, especially in
areas where a stretchable article with the properties of the
fibrous material are desired. For example, the elastic composite
may be used in applications such as bandages, durable wipes,
durable mops, in personal care products, such as diapers and
feminine napkins and/or agricultural products, such as a tree wrap
for saplings or trees.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 shows a representative process for preparing a
stretch-bonded laminate used in the present invention.
[0020] FIG. 2 shows a representative process for preparing elastic
composite of the present invention from a stretch-bonded
laminate.
DEFINITIONS
[0021] As used herein, the term "comprising" is inclusive or
open-ended and does not exclude additional unrecited elements,
compositional components, or method steps.
[0022] As used herein, the term "consisting essentially of" does
not exclude the presence of additional materials which do not
significantly affect the desired characteristics of a given
composition or product. Exemplary materials of this sort would
include, without limitation, pigments, antioxidants, stabilizers,
surfactants, waxes, flow promoters, particulates and materials
added to enhance processability of the composition.
[0023] The term "elastic" is used herein to mean any material
which, upon application of a biasing force, is stretchable in at
least one direction, that is, elongatable at least about 50 percent
(i.e., to a stretched, biased length which is at least about 150
percent of its relaxed unbiased length), and which, will recover at
least 50 percent of its elongation upon release of the stretching,
elongating force. A hypothetical example would be a 1.0 inch (2.54
cm) sample of a material which is elongatable to at least 1.50
inches (3.8 cm) and which, upon being elongated to 1.50 inches and
released, will recover to a length of not more than 1.25 inches
(3.13 cm) Many elastic materials may be elongated by much more than
50 percent (i.e., much more than 150 percent of their relaxed
length), for example, elongated 100 percent or more, and many of
these will recover to substantially their initial relaxed length,
for example, to within about 105 percent of their original relaxed
length, upon release of the stretching force.
[0024] The term "nonelastic" as used herein refers to any material
which does not fall within the definition of "elastic," above.
[0025] The terms "recover" and "recovery" as used herein refer to a
contraction of a stretched material upon termination of a biasing
force following stretching of the material by application of the
biasing force. For example, if a material having a relaxed,
unbiased length of 1.0 inch (2.54 cm) is elongated 50 percent by
stretching to a length of 1.5 inches (3.8 cm) the material would be
elongated 50 percent or 0.5 inch (1.27 cm) and would have a
stretched length that is 150 percent of its relaxed length. If this
exemplary stretched material contracted, that is recovered to a
length of 1.1 inches (2.8 cm) after release of the biasing and
stretching force, the material would have recovered 80 percent or
0.4 inch (1.0 cm) of its 0.5 inch (1.27 cm) elongation. Recovery
may be expressed as 1 % Recovery = ( maximum stretch length - final
sample length ) ( maximum stretch length - initial sample length )
.times. 100
[0026] The term "machine direction" as used herein refers to the
direction of travel of the forming surface onto which fibers are
deposited during formation of a nonwoven fibrous web.
[0027] The term "cross-machine direction" as used herein refers to
the direction which is perpendicular to the machine direction
defined above.
[0028] The term "stretch-to-stop" as used herein refers to the
ratio determined from the difference between the unextended
dimension of a composite elastic material and the maximum extended
dimension of a composite elastic material upon application of a
specified tensioning force and dividing that difference by the
unextended dimension of the composite elastic material. If the
stretch-to-stop is expressed in percent, this ratio is multiplied
by 100. For example, a composite elastic material having an
unextended length of 5 inches (12.7 cm) and a maximum extended
length of 10 inches (25.4 cm) upon applying a force of 2000 grams
has a stretch-to-stop (at 2000 grams) of 100 percent.
Stretch-to-stop may also be referred to as "maximum non-destructive
elongation". Unless specified otherwise, stretch-to-stop values are
reported herein at a load of 2000 grams.
[0029] The term "tenacity" as used herein refers to the resistance
to elongation of a composite elastic material which is provided by
its elastic component. Tenacity is the tensile load of a composite
elastic material at specified strain (i.e., elongation) for a given
width material divided by the basis weight of that composite
material's elastic component as measured at about the composite
material's stretch-to-stop elongation. For example, tenacity of a
composite elastic material is typically determined in one direction
(e.g., machine direction) at about the composite material's
stretch-to-stop elongation. Elastic materials having high values
for tenacity are desirable in certain applications because less
material is needed to provide a specified resistance to elongation
than a low tenacity material. For a specified sample width,
tenacity is reported in units of force divided by the units of
basis weight of the elastic component. This provides a measure of
force per unit area and is accomplished by reporting the thickness
of the elastic component in terms of its basis weight rather than
as an actual caliper measurement. For example, reported units may
be grams-force (for a specific sample width)/grams per square
meter.
[0030] As used herein, the term "nonwoven web" means a web having a
structure of individual fibers or threads which are interlaid, but
not in an identifiable, repeating manner. Nonwoven webs have been,
in the past, formed by a variety of processes such as, for example,
meltblowing processes, spunbonding processes and bonded carded web
processes.
[0031] As used herein, the term "autogenous bonding" means bonding
provided by fusion and/or self-adhesion of fibers and/or filaments
without an applied external adhesive or bonding agent. Autogenous
bonding may be provided by contact between fibers and/or filaments
while at least portions of the fibers and/or filaments are
semi-molten or tacky. Autogenous bonding may also be provided by
blending a tackifying resin with the thermoplastic polymers used to
form the fibers and/or filaments. Fibers and/or filaments formed
from such a blend can be adapted to self-bond with or without the
application of pressure and/or heat. Solvents may also be used to
cause fusion of fibers and filaments which remains after the
solvent is removed.
[0032] As used herein, the term "fiber" includes both staple
fibers, i.e., fibers which have a defined length between about 19
mm and about 60 mm, fibers longer than staple fiber but are not
continuous, and continuous fibers, which are sometimes called
"substantially continuous filaments" or simply "filaments". The
method in which the fiber is prepared will determine if the fiber
is a staple fiber or a continuous filament.
[0033] As used herein, the term "microfibers" means small diameter
fibers having an average diameter not greater than about 75
microns, for example, having an average diameter of from about 0.5
microns to about 50 microns, or more particularly, microfibers may
have an average diameter of from about 4 microns to about 40
microns.
[0034] As used herein, the term "meltblown fibers" means fibers
formed by extruding a molten thermoplastic material through a
plurality of fine, usually circular, die capillaries as molten
threads or filaments into converging high velocity, usually hot,
gas (e.g. air) streams which attenuate the filaments of molten
thermoplastic material to reduce their diameter, which may be to
microfiber diameter. Thereafter, the meltblown fibers are carried
by the high velocity gas stream and are deposited on a collecting
surface to form a web of randomly dispersed meltblown fibers. Such
a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to
Butin, which is hereby incorporated by reference in its entirety.
Meltblown fibers are microfibers, which may be continuous or
discontinuous, and are generally smaller than 10 microns in average
diameter The term "meltblown" is also intended to cover other
processes in which a high velocity gas, (usually air) is used to
aid in the formation of the filaments, such as melt spraying or
centrifugal spinning. As used herein the term "spunbond web" refers
to a nonwoven web prepared from small diameter fibers of
molecularly oriented polymeric material. Spunbond fibers may be
formed by extruding molten thermoplastic material as filaments from
a plurality of fine, usually circular capillaries of a spinneret
with the diameter of the extruded filaments then being rapidly
reduced as in, for example, U.S. Pat. No. 4,340,563 to Appel et
al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No.
3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394
to Kinney, U.S. Pat. No. 3,502,763 to Hartman, U.S. Pat. No.
3,542,615 to Dobo et al, and U.S. Pat. No. 5,382,400 to Pike et al.
Spunbond fibers are generally not tacky when they are deposited
onto a collecting surface and are generally continuous. Spunbond
fibers are often about 10 microns or greater in diameter. However,
fine fiber spunbond webs (having an average fiber diameter less
than about 10 microns) may be achieved by various methods
including, but not limited to, those described in commonly assigned
U.S. Pat. No. 6,200,669 to Marmon et al. and U.S. Pat. No.
5,759,926 to Pike et al., each is hereby incorporated by reference
in its entirety.
[0035] As used herein, the phrase "Bonded carded web" or "BCW"
refers to webs that are made from staple fibers which are sent
through a combing or carding unit, which separates or breaks apart
and aligns the staple fibers in the machine direction to form a
generally machine direction-oriented fibrous nonwoven web. Such
fibers are usually purchased in bales which are placed in an
opener/blender or picker which separates the fibers prior to the
carding unit. Once the web is formed, it then is bonded by one or
more of several known bonding methods. One such bonding method is
powder bonding, wherein a powdered adhesive is distributed through
the web and then activated, usually by heating the web and adhesive
with hot air. Another suitable bonding method is pattern bonding,
wherein heated calender rolls or ultrasonic bonding equipment are
used to bond the fibers together, usually in a localized bond
pattern, though the web can be bonded across its entire surface if
so desired. Another suitable and well-known bonding method,
particularly when using bicomponent staple fibers, is through-air
bonding.
[0036] "Airlaying" or "airlaid" is a well known process by which a
fibrous nonwoven layer can be formed. In the airlaying process,
bundles of small fibers having typical lengths ranging from about 3
to about 19 millimeters (mm) are separated and entrained in an air
supply and then deposited onto a forming screen, usually with the
assistance of a vacuum supply. The randomly deposited fibers then
are bonded to one another using, for example, hot air or a spray
adhesive.
[0037] As used herein, the term "polymer" generally includes, but
is not limited to, homopolymers, copolymers, such as, for example,
block, graft, random and alternating copolymers, terpolymers, etc.
and blends and modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometrical configurations of the material. These configurations
include, but are not limited to, isotactic, syndiotactic and random
symmetries.
[0038] As used herein, the term "superabsorbent" refers to
absorbent materials capable of absorbing at least 10 grams of
aqueous liquid (e.g. distilled water per gram of absorbent
material) while immersed in the liquid for 4 hours and holding
substantially all of the absorbed liquid while under a compression
force of up to about 1.5 psi.
DETAILED DESCRIPTION OF THE INVENTION
[0039] The present invention provides an elastic composite material
having an elastic layer with a first side and a second side; at
least one gatherable layer bonded to at least one of the first side
and second side of the elastic layer; and a fibrous material
entangled and intertwined with both the elastic layer and the
gatherable layer. The resulting elastic composite provides a
stretchable material which can conform to surfaces and has
desirable properties of the fibrous material entangled and
intertwined with the elastic layer and does not suffer from the
loss of the fibrous material from the stretchable substrate.
[0040] A variety of materials may be employed as the elastic layer.
The elastic layer can be an elastomeric film, an elastomeric
nonwoven web, a plurality of substantially continuous elastomeric
filaments arranged in substantially parallel rows, or a laminate of
an elastomeric nonwoven web and a plurality of substantially
continuous elastomeric filaments arranged in substantially parallel
rows.
[0041] Desirably, the elastic layer contains a meltblown nonwoven
web prepared from an elastomeric polymer such as, for example,
elastomeric polyesters, elastomeric polyurethanes, elastomeric
polyamides, elastomeric copolymers of ethylene and at least one
vinyl monomer, and elastomeric A-B-A' block copolymers wherein A
and A' are the same or different thermoplastic polymer, and wherein
B is an elastomeric polymer block. The elastomeric polymer may be
blended with a processing aid.
[0042] For example, the elastomeric meltblown fibers may be made
from elastomeric block copolymers. Exemplary elastomeric block
copolymers may have the general formula A-B-A' where A and A' are
each a thermoplastic polymer endblock which contains a styrenic
moiety such as a poly (vinyl arene) and where B is an elastomeric
polymer midblock such as a conjugated diene or a lower alkene
polymer. The block copolymers may be, for example,
(polystyrene/poly(ethylene-butylene)/polystyrene) block copolymers
available from the Kraton Polymers, under the trademark KRATON.RTM.
G. One such block copolymer may be, for example, KRATON.RTM.
G-1657.
[0043] Other exemplary elastomeric materials which may be used
include polyurethane elastomeric materials such as, for example,
those available under the trademark ESTANE from Noveon., polyamide
elastomeric materials such as, for example, those available under
the trademark PEBAX from Atofina Chemicals, and polyester
elastomeric materials such as, for example, those available under
the trade designation Hytrel from E.I. DuPont De Nemours &
Company. Formation of elastomeric meltblown fibers from polyester
elastic materials is disclosed in, for example, U.S. Pat. No.
4,741,949 to Morman et al., hereby incorporated by reference.
Useful elastomeric polymers also include, for example, elastic
copolymers of ethylene and at least one vinyl monomer such as, for
example, vinyl acetates, unsaturated aliphatic monocarboxylic
acids, and esters of such monocarboxylic acids. The elastic
copolymers and formation of elastomeric meltblown fibers from those
elastic copolymers are disclosed in, for example, U.S. Pat. No.
4,803,117 to Daponte, hereby incorporated by reference.
[0044] Processing aids may be added to the elastomeric polymer. For
example, a polyolefin may be blended with the elastomeric polymer
(e.g., the elastomeric block copolymer) to improve the
processability of the composition. The polyolefin must be one
which, when so blended and subjected to an appropriate combination
of elevated pressure and elevated temperature conditions, is
extrudable, in blended form, with the elastomeric polymer. Useful
blending polyolefin materials include, for example, polyethylene,
polypropylene and polybutene, including ethylene copolymers,
propylene copolymers and butene copolymers. Extrudable blends of
elastomeric polymers and polyolefins are disclosed in, for example,
previously referenced U.S. Pat. No. 4,663,220.
[0045] Desirably, the elastomeric meltblown fibers should have some
tackiness or adhesiveness to enhance autogenous bonding. For
example, the elastomeric polymer itself may be tacky when formed
into fibers or, alternatively, a compatible tackifying resin may be
added to the extrudable elastomeric compositions described above to
provide tackified elastomeric fibers that autogenously bond. In
regard to the tackifying resins and tackified extrudable
elastomeric compositions, note the resins and compositions as
disclosed in U.S. Pat. No. 4,787,699, hereby incorporated by
reference.
[0046] Any tackifier resin can be used which is compatible with the
elastomeric polymer and can withstand the high processing (e.g.,
extrusion) temperatures. If the elastomeric polymer (e.g.,
elastomeric block copolymer) is blended with processing aids such
as, for example, polyolefins or extending oils, the tackifier resin
should also be compatible with those processing aids. Generally,
hydrogenated hydrocarbon resins are preferred tackifying resins,
because of their better temperature stability. REGALREZ.RTM. and
ARKON.RTM. P series tackifiers are examples of hydrogenated
hydrocarbon resins. ZONATAK.RTM.501 lite tackifier resin is an
example of a terpene hydrocarbon. REGALREZ.RTM. hydrocarbon resins
are available from Eastman Chemical Company. ARKON.RTM. P series
resins are available from Arakawa Chemical (U.S.A.) Incorporated.
Of course, the present invention is not limited to use of such
three tackifying resins, and other tackifying resins which are
compatible with the other components of the composition and can
withstand the high processing temperatures, can also be used.
[0047] Typically, the blend used to form the elastomeric fibers
include, for example, from about 40 to about 80 percent by weight
elastomeric polymer, from about 5 to about 40 percent polyolefin
and from about 5 to about 40 percent resin tackifier. For example,
a particularly useful composition included, by weight, about 61 to
about 65 percent KRATON.RTM. G-1657, elastomer about 17 to about 23
percent polyethylene NA 601, and about 15 to about 20 percent
REGALREZ.RTM. 1126 tackifying resin.
[0048] The elastomeric nonwoven web may also include a
substantially homogenous mixture of meltblown fibers and other
fibrous materials and/or particulates. Exemplary materials and
processes are disclosed in, for example, U.S. Pat. Nos. 4,209,563
and 4,741,949.
[0049] In one aspect of the present invention, the elastic layer is
an anisotropic elastic fibrous web containing at least one layer of
elastomeric meltblown fibers and at least one layer of
substantially parallel rows of elastomeric filaments. The
substantially parallel rows of elastomeric filaments are
autogenously bonded to at least a portion of the meltblown fibers.
This autogenous bonding may take place, for example, by forming
molten elastomeric filaments directly on a layer of meltblown
fibers. Likewise, a layer of meltblown fibers may be formed
directly on a layer of substantially parallel rows of elastomeric
filaments to provide the desired autogenous bonding.
[0050] When the elastic layer contains at least two layers of
materials, at least one layer is a layer of elastomeric meltblown
fibers and at least one other layer is a layer containing
substantially parallel rows of elastomeric filaments autogenously
bonded to at least a portion of the elastomeric meltblown fibers.
These elastomeric filaments have an average diameter ranging from
about 40 to about 750 microns and extend along length (i.e. machine
direction) of the fibrous web to improve the tenacity of the
fibrous web in that direction.
[0051] Desirably, the elastomeric filaments may have an average
diameter in the range from about 50 to about 500 microns, for
example, from about 100 to about 200 microns. These elastomeric
filaments extend along length (i.e. machine direction) of the
fibrous web so that the tenacity of the elastic fibrous web is
greater in that direction than the tenacity of a substantially
nonwoven web without the continuous filaments of about the same
basis weight. For example, the tenacity of the elastic fibrous web
with the continuous filaments may be about 20 to about 90 percent
greater in the machine direction than the tenacity of a
substantially nonwoven web of about the same basis weight
containing only elastomeric meltblown fibers.
[0052] Typically, the elastic fibrous layer will contain at least
about 20 percent, by weight, of continuous elastomeric filaments.
For example, the elastic fibrous web may contain from about 20
percent to about 80 percent, by weight, of the elastomeric
filaments. Desirably, the continuous elastomeric filaments will
constitute from about 40 to about 60 percent, by weight, of the
elastic fibrous layer. The elastic layer may also be composed of
only of the continuous filaments.
[0053] The elastomers used to produce the meltblown filaments may
also be used to form the continuous elastomeric filaments. The
meltblown fibers and the continuous filaments may be prepared from
the same elastomeric material or from different elastomeric
materials.
[0054] The gatherable layer, or layers if two gatherable layers are
present in the elastic composite, may be a woven, knit material or
a nonwoven web from a thermoplastic polymer. By selecting a woven,
knit of nonwoven webs of thermoplastic polymers, the gatherable may
be easily bonded to the elastic layer. Desirably, the gatherable
layer can be a nonwoven web of fibers, such as, for example, a web
of spunbond fibers, a web of meltblown fibers, a bonded carded web
of fibers, a multilayer material including at least one of a
spunbond layer, a meltblown layer and/or a bonded carded web.
Optionally, the gatherable layer can be a composite material
composed of a mixture of fibers and one or more other materials
such as, for example, wood pulp, staple fibers, particulates or
super-absorbent materials. Medicinal materials may be mixed with
the fibrous materials of the gatherable layer. Such mixtures may be
formed by adding fibers and/or particulates to the gas stream in
which meltblown fibers are carried so that an intimate entangled
commingling of meltblown fibers and other materials, e.g., wood
pulp, staple fibers and particulates such as, for example,
hydrocolloid (hydrogel) particulates commonly referred to as
superabsorbent materials, occurs prior to collection of the
meltblown fibers upon a collecting device to form a coherent web of
randomly dispersed meltblown fibers and other materials such as
disclosed in U.S. Pat. No. 4,100,324, the disclosure of which is
hereby incorporated by reference. In order to provide strength to
the stretch-bonded laminate, desirably the gatherable layer
contains a spunbond nonwoven web. The gatherable layer may also be
a multilayer material having two of more of the above mentioned
gatherable layer laminated together. For example, at least one
layer of a spunbond web may be joined to at least one layer of
meltblown web, bonded carded web or other suitable material.
[0055] In the practice of the present invention, the gatherable
layer may be joined to one side of the elastic layer or to both
sides of the elastic layer. Desirably, the gatherable layer is
joined to both sides of the elastic material. The gatherable layer
or layers are joined to the elastic layer by any suitable means,
such as, for example, thermal bonding or ultrasonic bonding, which
will soften at least portions of at least one of the materials,
usually the a material of the elastic layer, the elastomeric
materials used for elastic layer have a lower softening point than
the components of the gatherable layers. Joining may be produced by
applying heat and/or pressure to the overlaid elastic layer and the
gatherable layer or layers by heating these portions (or the
overlaid layer) to at least the softening temperature of the
material with the lowest softening temperature to form a reasonably
strong and permanent bond between the re-solidified softened
portions of the elastic layer and the gatherable layers. It is
desirable that the gatherable layer (or layers) is bonded to the
elastic layer at spaced apart locations, so that the gatherable
layer will pucker when the elastic layer is in a relaxed
condition.
[0056] The bonder roller arrangement may be a smooth anvil roller
and a patterned calender roller, such as, for example, a pin
embossing roller arranged with a smooth anvil roller. One or both
of the smooth anvil roller and the calender roller may be heated
and the pressure between these two rollers may be adjusted by
well-known means to provide the desired temperature, if any, and
bonding pressure to join the gatherable layers to the elastic
fibrous web. As can be appreciated, the bonding between the
gatherable layers and the elastic sheet is a point bonding. Various
bonding patterns can be used, depending upon the desired tactile
properties of the final composite laminate material. When the
gatherable layer is a material such as, for example, spunbond
polypropylene, the bonding can be performed at temperatures as low
as 60.degree. F. A range of temperatures for the calender rolls
during bonding between a gatherable layer such as, for example,
spunbond polypropylene and an elastic sheet is 60.degree. to
180.degree. F.
[0057] With regard to thermal bonding, one skilled in the art will
appreciate that the temperature to which the materials, or at least
the bond sites thereof, are heated for heat bonding will depend not
only on the temperature of the heated roll(s) or other heat sources
but on the residence time of the materials on the heated surfaces,
the compositions of the materials, the basis weights of the
materials and their specific heats and thermal conductivities.
However, for a given combination of materials, and in view of the
herein contained disclosure the processing conditions necessary to
achieve satisfactory bonding can be readily determined by one of
skill in the art.
[0058] The fibrous material which is entangled with the gatherable
layer and the elastic layer of the present invention may include
absorbent fibers or non-absorbent fibers. This material may
generally be made up of fibers such as polyester fibers, polyamide
fibers, cellulosic derived fibers such as, for example, rayon
fibers and wood pulp fibers, multi-component fibers such as, for
example, sheath-core multi-component fibers, natural fibers such as
silk fibers, wool fibers or cotton fibers or electrically
conductive fibers or blends of two or more of such secondary
fibers. Other types of fibrous material such as, for example,
polyethylene fibers and polypropylene fibers, as well as blends of
two or more of other types of fibrous material may be utilized. The
fibers may be microfibers, i.e. fibers having a fiber diameter less
than 75 microns or the secondary fibers may be macrofibers having
an average diameter of from about 75 microns to about 1,000
microns.
[0059] The selection of the fibrous material will determine the
properties of the resulting the resulting composite. For example,
the absorbency of the composite material can be improved by using
an absorbent material as the fibrous material. In the case were
absorbency is not necessary or not desired, non-absorbent material
may be selected as the secondary material.
[0060] The absorbent materials useful in the present invention
include absorbent fibers. Examples of the absorbent material
include, but are not limited to, fibrous organic materials such as
woody or non-woody pulp from cotton, rayon, recycled paper, pulp
fluff, inorganic absorbent materials, treated polymeric staple
fibers and so forth. Desirably, although not required, the
absorbent material is pulp.
[0061] The pulp fibers may be any high-average fiber length pulp,
low-average fiber length pulp, or mixtures of the same. Preferred
pulp fibers include cellulose fibers. The term "high average fiber
length pulp" refers to pulp that contains a relatively small amount
of short fibers and non-fiber particles. High fiber length pulps
typically have an average fiber length greater than about 1.5 mm,
preferably about 1.5-6 mm. Sources generally include non-secondary
(virgin) fibers as well as secondary fiber pulp which has been
screened. The term "low average fiber length pulp" refers to pulp
that contains a significant amount of short fibers and non-fiber
particles. Low average fiber length pulps typically have an average
fiber length less than about 1.5 mm.
[0062] Examples of high average fiber length wood pulps include
those available from Georgia-Pacific under the trade designations
Golden Isles 4821 and 4824. The low average fiber length pulps may
include certain virgin hardwood pulp and secondary (i.e., recycled)
fiber pulp from sources including newsprint, reclaimed paperboard,
and office waste. Mixtures of high average fiber length and low
average fiber length pulps may contain a predominance of low
average fiber length pulps. For example, mixtures may contain more
than about 50% by weight low-average fiber length pulp and less
than about 50% by weight high-average fiber length pulp. One
exemplary mixture contains about 75% by weight low-average fiber
length pulp and about 25% by weight high-average fiber length
pulp.
[0063] The pulp fibers may be unrefined or may be beaten to various
degrees of refinement. Crosslinking agents and/or hydrating agents
may also be added to the pulp mixture. Debonding agents may be
added to reduce the degree of hydrogen bonding if a very open or
loose nonwoven pulp fiber web is desired. Exemplary debonding
agents are available from the Quaker Oats Chemical Company,
Conshohocken, Pa., under the trade designation Quaker 2028 and
Berocell 509ha made by Akzo Nobel, Inc. Marietta, Ga. The addition
of certain debonding agents in the amount of, for example, 1-4% by
weight of the pulp fibers may be added to the pulp fibers. The
debonding agents act as lubricants or friction reducers. Debonded
pulp fibers are commercially available from Weyerhaeuser Corp.
under the designation NB 405.
[0064] In addition, non-absorbent fibrous material can be
incorporated into the stretch-bonded laminate, depending on the end
use of composite material. For example, in end uses where
absorbency is not an issue, non-absorbent secondary materials may
be used. Examples of the fibers include, for example, staple fibers
of untreated thermoplastic polymers, such as polyolefins and the
like.
[0065] The elastic composite of the present may be prepared by a
process including the steps of providing the elastic layer;
providing the gatherable layer; applying a stretching force to the
elastic layer to form a stretched elastic layer having a first side
and a second side; bonding the gatherable layer to the stretched
elastic layer to at least the first side or the second side of the
elastic layer to form a stretch bonded laminate; providing the
fibrous material onto the gatherable layer of the stretch bonded
laminate; entangling the fibrous material into the stretch bonded
laminate; and relaxing the stretching force. Although not
necessary, the stretch-bonded laminate may be prepared on a
separate line and transported to the entangling line.
[0066] Referring now to the drawings wherein like reference
numerals represent the same or equivalent structure and, in
particular, to FIG. 1 of the drawings there is schematically
illustrated a process 10 for forming a stretch-bonded laminate
which includes an elastic web 12 and two gatherable layers 24 and
26. The elastic layer 12 is unwound from a supply roll 14 and
travels in the direction indicated by the arrow associated
therewith as the supply roll 14 rotates in the direction of the
arrows associated therewith. The elastic layer 12 passes through a
nip 16 of the S-roll arrangement 18 formed by the stack rollers 20
and 22.
[0067] The elastic web 12 may also be formed in-line in a
continuous process, using a known process in the art, and passed
directly through the nip 16 without first being stored on a supply
roll. A first gatherable layer 24 is unwound from a supply roll 26
and travels in the direction indicated by the arrow associated
therewith as the supply roll 26 rotates in the direction of the
arrows associated therewith. Optionally, a second gatherable layer
28 is unwound from a second supply roll 30 and travels in the
direction indicated by the arrow associated therewith as the supply
roll 30 rotates in the direction of the arrows associated
therewith. The first gatherable layer 24 and second gatherable
layer 28 pass through the nip 32 of the bonder roller arrangement
34 formed by the bonder rollers 36 and 38. The first gatherable
layer 24 and/or the second gatherable layer 28 may be formed by
extrusion processes such as, for example, meltblowing processes,
spunbonding processes and passed directly through the nip 32
without first being stored on a supply roll. Both the elastic layer
and the gatherable layers may be formed in-line without the need to
first store the layers on a supply roll.
[0068] The elastic layer web 12 passes through the nip 16 of the
S-roll arrangement 18 in a reverse-S path as indicated by the
rotation direction arrows associated with the stack rollers 20 and
22. From the S-roll arrangement 18, the elastic layer web 12 passes
through the pressure nip 32 formed by a bonder roller arrangement
34. Additional S-roll arrangements (not shown) may be introduced
between the S-roll arrangement and the bonder roller arrangement to
stabilize the stretched material and to control the amount of
stretching. Because the peripheral linear speed of the rollers of
the S-roll arrangement 18 is controlled to be less than the
peripheral linear speed of the rollers of the bonder roller
arrangement 34, the elastic layer web 12 is tensioned between the
S-roll arrangement 18 and the pressure nip of the bonder roll
arrangement 32. By adjusting the difference in the speeds of the
rollers, the elastic layer web 12 is tensioned so that it stretches
a desired amount and is maintained in such stretched condition
while the first gatherable layer 24 and second gatherable layer 28
is joined to the anisotropic elastic fibrous web 12 during their
passage through the bonder roller arrangement 34 to form a
composite elastic material 40.
[0069] The composite elastic material 40 immediately relaxes upon
release of the tensioning force provided by the S-roll arrangement
18 and the bonder roll arrangement 34, whereby the first gatherable
layer 24 and the second gatherable layer 28 are gathered in the
composite elastic material 40. The composite elastic material 40 is
then wound up on a winder 42. Processes of making composite elastic
materials of this type are described in, for example, U.S. Pat. No.
4,720,415, the disclosure of which is hereby incorporated by
reference.
[0070] With regard to bonding, one or both of the bonder rolls 36
and/or 38 may be heated. Both rolls may have a bond pattern or one
roll may have a bond pattern and the other roll will have a smooth
surface and act as an anvil-type roll. As is noted above, one
skilled in the art will appreciate that the temperature to which
the materials, or at least the bond sites thereof, are heated for
thermal bonding will depend not only on the temperature of the
heated roll(s) or other heat sources but on the residence time of
the materials on the heated surfaces and the pressure exerted by
these rolls, the compositions of the materials, the basis weights
of the materials and their specific heats and thermal
conductivities. However, for a given combination of materials, and
in view of the herein contained disclosure the processing
conditions necessary to achieve satisfactory bonding can be readily
determined by one of skill in the art.
[0071] Conventional drive means and other conventional devices
which may be utilized in conjunction with the apparatus of FIG. 1
are well known and, for purposes of clarity, have not been
illustrated in the schematic view of FIG. 1.
[0072] Once the stretch-bonded laminate is formed, the fibrous
material to be entangled with the stretch-bonded laminate is
contacted with the stretch-bonded laminate. Any method known in the
art use to entangle a fibrous material with a substrate can be
used. Of the known methods, desirably hydraulic entangling is used.
In hydraulic entangling, the jetting of a plurality of high
pressure liquid streams towards the material is used so that the
material is intertwined with both the elastic layer and the
gatherable layer.
[0073] An exemplary hydraulic entangling process is shown in FIG.
2. In FIG. 2, an embodiment of the present invention for
hydraulically entangling a fibrous material with the stretch-bonded
laminate is illustrated. As shown, a fibrous slurry containing
fibrous material is conveyed to a conventional papermaking headbox
112 where it is deposited via a sluice 114 onto a conventional
forming fabric or surface 116. The suspension of fibrous material
may have any consistency that is typically used in conventional
papermaking processes. For example, the suspension may contain from
about 0.01 to about 1.5 percent by weight fibrous material
suspended in water. Water is then removed, using a known technique,
such as a suction box, from the suspension of fibrous material to
form a uniform layer of the fibrous material 118.
[0074] The stretch-bonded laminate 120 is also unwound from a
supply roll 122 and travels in the direction indicated by the arrow
associated therewith as the supply roll 122 rotates in the
direction of the arrows associated therewith. The stretch-bonded
laminate 120 passes through a nip 124 of an S-roll arrangement 126
formed by the stack rollers 128 and 130 which causes the
stretched-bonded laminate to be stretched in the machine direction.
The guide rollers 131 help maintain the tension of the stretched
stretch-bonded laminate 120. In the stretched state, the
stretch-bonded laminate 120 is then placed upon a foraminous
entangling surface 132 of a conventional hydraulic entangling
machine where the cellulosic fibrous layer 118 is then laid on the
stretch-bonded laminate 120. Although not required, it is typically
desired that the fibrous layer 118 be between the stretch-bonded
laminate 120 and the hydraulic entangling manifolds 134. The
fibrous layer 118 and stretch-bonded laminate 120 pass under one or
more hydraulic entangling manifolds 134 and are treated with jets
of fluid to entangle the fibrous material with the fibers of the
gatherable layer and the elastic layer of the stretch-bonded
laminate 120. The jets of fluid also drive fibrous material into
the stretch-bonded laminate 120 to form the composite fabric
136.
[0075] Alternatively, hydraulic entangling may take place while the
fibrous layer 118 and stretch-bonded laminate 120 are on the same
foraminous screen (e.g., mesh fabric) that the wet-laying took
place. The present invention also contemplates superposing a dried
fibrous sheet on a nonwoven web, rehydrating the dried sheet to a
specified consistency and then subjecting the rehydrated sheet to
hydraulic entangling. The hydraulic entangling may take place while
the fibrous layer 118 is highly saturated with water. For example,
the fibrous layer 118 may contain up to about 90% by weight water
just before hydraulic entangling. Alternatively, the fibrous layer
118 may be an air-laid or dry-laid layer.
[0076] Hydraulic entangling may be accomplished utilizing
conventional hydraulic entangling equipment such as described in,
for example, in U.S. Pat. No. 3,485,706 to Evans, which is
incorporated herein in its entirety by reference. Hydraulic
entangling may be carried out with any appropriate working fluid
such as, for example, water. The working fluid flows through a
manifold that evenly distributes the fluid to a series of
individual holes or orifices. These holes or orifices may be from
about 0.003 to about 0.015 inch in diameter and may be arranged in
one or more rows with any number of orifices, e.g., 30-100 per
inch, in each row. For example, a manifold produced by Honeycomb
Systems Incorporated of Biddeford, Me., containing a strip having
0.007-inch diameter orifices, 130 holes per inch, and 1 row of
holes may be utilized. However, it should also be understood that
many other manifold configurations and combinations may be used.
For example, a single manifold may be used or several manifolds may
be arranged in succession.
[0077] Fluid can impact the fibrous material of the fibrous layer
118 and the stretched stretch-bonded laminate 120, which are
supported by a foraminous surface, such as a single plane mesh
having a mesh size of from about 40.times.40 to about
100.times.100. The foraminous surface may also be a multi-ply mesh
having a mesh size from about 50.times.50 to about 200.times.200.
As is typical in many water jet treatment processes, vacuum slots
138 may be located directly beneath the hydro-needling manifolds or
beneath the foraminous entangling surface 132 downstream of the
entangling manifold so that excess water is withdrawn from the
hydraulically entangled composite material 136.
[0078] Although not held to any particular theory of operation, it
is believed that the columnar jets of working fluid that directly
impact cellulosic fibers 118 laying on the stretch-bonded laminate
120 work to drive those fibers into and partially through the
matrix or network of fibers in the stretch-bonded laminate 120.
When the fluid jets and cellulosic fibers 18 interact with a
stretch-bonded laminate 120, the cellulosic fibers 118 are also
entangled with fibers of the nonwoven web 120 and with each other.
To achieve the desired entangling of the fibers, it is typically
desired that hydroentangling be performed using water pressures
from about 100 to 3000 psig, and in some embodiments from about
1200 to 2000 psig. When processed at the upper ranges of the
described pressures, the composite fabric 136 may be processed at
speeds of up to about 1000 feet per minute (fpm).
[0079] The pressure of the jets in the entangling process is
typically at least about 100 psig because lower pressures often do
not generate the desired degree of entanglement. However, it should
be understood that adequate entanglement may be achieved at
substantially lower water pressures. In addition, greater
entanglement may be achieved, in part, by subjecting the fibers to
the entangling process two or more times. Thus, it may be desirable
that the web be subjected to at least one run under the entangling
apparatus, wherein the water jets are directed to the first side
and an additional run wherein the water jets are directed to the
opposite side of the web.
[0080] After the fluid jet treatment, the resulting composite
fabric 136, the stretched bonded laminate is released from its
stretched condition and may then be transferred to a
non-compressive drying operation. A differential speed pickup roll
140 may be used to transfer the material from the hydraulic
needling belt to a non-compressive drying operation. Alternatively,
conventional vacuum-type pickups and transfer fabrics may be used.
If desired, the composite fabric 136 may be wet-creped before being
transferred to the drying operation. Non-compressive drying of the
fabric 136 may be accomplished utilizing a conventional rotary drum
through-air drying apparatus 142. The through-dryer 142 may be an
outer rotatable cylinder 144 with perforations 146 in combination
with an outer hood 148 for receiving hot air blown through the
perforations 146. A through-dryer belt 150 carries the composite
fabric 136 over the upper portion of the through-dryer outer
cylinder 140. The heated air forced through the perforations 146 in
the outer cylinder 144 of the through-dryer 142 removes water from
the composite fabric 136. The temperature of the air forced through
the composite fabric 136 by the through-dryer 142 may range from
about 200.degree. F. to about 500.degree. F. Other useful
through-drying methods and apparatus may be found in, for example,
U.S. Pat. No. 2,666,369 to Niks and U.S. Pat. No. 3,821,068 to
Shaw, which are incorporated herein in their entirety by reference
thereto for all purposes.
[0081] The resulting composite material exhibits durability,
texture, elasticity, absorbency, is low linting, has high strength
and a durable wet texture. These properties make the composite
material in applications were these properties are needed or
desired, such as, for example, in wet and dry wipe applications,
bandages, absorbent bandages, floor mops, personal care products
such as diapers, training pants and feminine care products,
agricultural products, such as a tree wrap for saplings or trees,
or sorbents.
[0082] One particularly notable use of the composite is in the area
of bandages. When used as a bandage material, it is usually
desirable to have the bandage to be self adhesive. In order to make
the bandage self adhesive, a coating of a self-adhesive material is
added to at least a portion of at least one exterior surface of the
elastic composite material so that the peel strength of the
self-adhesive material is less than the peel strength of the layers
which bind the elastic composite material. It is very desirable
that the peel strength of the self-adhesive material be less than
the peel strength which binds the elastic composite material to
prevent delamination (i.e., separation of the layers) of the
elastic composite material.
[0083] For example, the peel strength of the self-adhesive material
may be at least about 5 percent less than the peel strength which
binds the elastic composite material. As another example, the peel
strength of the self-adhesive material may be from about 10 to
about 98 percent less than the peel strength which binds the
elastic composite material. As a further example, the peel strength
of the self-adhesive material may be from about 20 to about 95
percent less than the peel strength which binds the elastic
composite material. Desirably, the peel strength of the
self-adhesive material will be from about 0.1 to about 1.0 pound
per inch. For example, the peel strength of the self-adhesive
material may be from about 0.3 to about 0.5 pound per inch.
Desirably, the amount of force required to unwind a roll of the
self-adhesive material will be from about 0.3 to about 2.0 pounds
per inch. For example, the amount of force required to unwind a
roll of the self-adhesive material may be from about 0.5 to about
1.2 pounds per inch.
[0084] The coating of self-adhesive material may be located on the
gatherable material. In some embodiments, the coating of
self-adhesive material may be located only on raised portions of
the gathers present in the gatherable material. Where the composite
material is composed of one layer of gatherable material and a
layer of an elastomeric fibrous web, the coating of self-adhesive
material can be located on the elastomeric fibrous web.
[0085] While it is contemplated that the self-adhesive material may
be an organic solvent based adhesive or water based adhesive (e.g.,
latex adhesive) that can be printed, brushed or sprayed onto the
elastic composite material, it is desirable that the coating of
self adhesive material be in the form of a randomly scattered
network of hot-melt adhesive filaments and/or fibers produced by
conventional hot-melt adhesive spray equipment. The coating of
hot-melt self-adhesive material may also desirably be applied in
patterns such as, for example, semi-cycloidal patterns. For
example, a self-adhesive material such as a hot-melt self adhesive
material may be applied to a composite elastic material as
generally described by U.S. Pat. No. 4,949,668 to Heindel, et al.,
issued Aug. 21, 1990, which is hereby incorporated by reference.
Desirably, the hot-melt adhesive coating should be applied while
the stretch-bonded laminate material is under a relatively small
amount of tension. For example, the hot-melt adhesive coating can
be applied while the elastic composite material is under only
enough tension needed to have the material travel through the
adhesive application process.
[0086] The coating of self-adhesive material may be a coating of
any suitable conventional commercially available hot-melt adhesive
such as, for example, hot melt adhesives which may contain a blend
of thermoplastic polymers (e.g., thermoplastic polyolefins),
adhesive resins, and waxes.
[0087] Exemplary hot-melt self-adhesive materials which may be used
include auto-adhesive 6631-117-1 and auto-adhesive 6631-114-4
available from the National Starch & Chemical Company,
Adhesives Division, Bridgewater, N.J. Other self-adhesive materials
may be, for example, Hot Melt Adhesive H-9140 available from
Findley Adhesives, Incorporated, Wauwatosa, Wis. These
self-adhesive materials may be blended with other materials such
as, for example antioxidants, stabilizers, surfactants, flow
promoters, particulates and materials added to enhance
processability of the composition.
EXAMPLE
[0088] The elastic layer of the composite is prepared in accordance
with the Example of U.S. Pat. No. 5,385,775. A four-bank
meltblowing process in which each bank was a conventional meltblown
fiber forming apparatus was setup to extrude an elastomeric
composition which contained about 63 percent, by weight,
KRATON.RTM. G-1657, about 17 percent, by weight, polyethylene NA
601, and about 20 percent, by weight, REGALREZ.RTM. 1126.
Meltblowing bank 1 was set-up to produce meltblown fibers; banks 2
and 3 were set-up to produce continuous filaments; and bank 4 was
set-up to produce meltblown fibers. Each bank contained an
extrusion tip having 0.016 inch diameter holes spaced at a density
of about 30 capillary per lineal inch. The polymer was extruded
from the first bank at a rate of about 0.58 grams per capillary per
minute (about 2.3 pounds per liner inch per hour) at a height of
about 11 inches above the forming surface. A primary air-flow of
about 14 ft.sup.3/minute per inch of meltblowing die at about 3 psi
was used to attenuate the extruded polymer into meltblown fibers
and microfibers that were collected on a foraminous surface moving
at a constant speed. The meltblown fibers were carried downstream
on the foraminous surface to the second bank which was an identical
meltblown system except that the primary air flow was eliminated.
The polymer was extruded at the same temperature and throughput
rates into substantially parallel continuous filaments at a density
of 30 filaments per lineal inch. A secondary air flow chilled to
about 50 degrees Fahrenheit was used to cool the filaments. The
difference in speed between the continuous filaments leaving the
die tips and the foraminous surface aided the alignment of the
continuous filaments into substantially parallel rows. The laminate
of meltblown fibers and continuous filaments was carried to the
third bank where an identical layer of substantially parallel
continuous filaments was deposited at the same process conditions.
This material was then carried to a fourth bank where a final layer
of elastomeric meltblown fibers was deposited onto the multi-layer
structure at the same conditions as the first bank. The layers of
the structure were joined by autogenous bonding produced by
directly forming one layer upon the other and enhanced by the
tackifier resin added to the polymer blend. This material had 2
layers of meltblown fibers and 2 layers of substantially parallel
continuous filaments (for a total filament density of about 60
filaments per lineal inch), a basis weight of about 60 gsm, and
weight ratio of filaments to fibers of about 50:50. The tensile
test revealed a strength index (i.e., machine direction tension
versus cross-machine direction tension) from about 3 to about 5
when the tension was measured at an elongation of about 400
percent.
[0089] The four-layer elastic fibrous web was moved along at a rate
of about 100 feet/minute by the foraminous wire, lifted off the
wire by a pick-off roll moving at a rate about 50% faster and then
drawn to a ratio of 2:1(200%). At this extension the drawn elastic
fibrous web was fed into a calender roller along with upper and
lower non-elastic gatherable facings. Each gatherable facing was a
conventional polypropylene spunbond web having a basis weight 0.35
ounces per square yard (about 12 gsm) which was joined to the
anisotropic elastic fibrous web at spaced apart locations to form a
stretch-bonded laminate structure. The stretched-bonded laminate
was relaxed as it exited the nip so that gathers and puckers would
form. The laminate was wound onto a driven wind-up roll under
slight tension and has a basis weight of about 2.5 osy (85 gsm)
[0090] Next the stretch-bonded laminate was hydroentangled with
pulp at a pulp addition of about 1.0 osy (34 gsm) and 2.0 osy (68
gsm). A wet slurry of pulp fibers was formed using conventional
paper making process conditions. The wet slurry of pulp fibers was
transported on a wire. The stretch-bonded laminate prepared above
was removed from the storage roll and stretched to about 100%. The
wet slurry of pulp fibers was placed onto the stretched
stretch-bonded laminate and the two layers were moved via a forming
wire into a hydroentangling unit having two manifolds. The pulp was
hydraulically entangled into a composite material utilizing 2
manifolds. Each manifold was equipped with a jet strip having one
row of 0.007 inch holes at a density of 30 holes per inch. Water
pressure in the manifold was 1800 psi (gage). The layers were
supported on a C-9 coarse forming wire which traveled under the
manifolds at a rate of about 45 fpm. The composite fabric was dried
utilizing conventional through-air drying equipment. The composites
had a total basis weight of about 120 gsm (34 gsm pulp add-on) and
154 gsm (68 gsm pulp add-on).
Example 2
[0091] The 120 gsm composite of Example 1 was coated onto both
sides with about 2 gsm of an Ato Findley H 2174-01 hot melt
adhesive, while in the relaxed condition. The adhesive containing
composite was cut into a bandage 3 inches wide and 20 inches long.
With the adhesive coated on the composite and cut to size, the
composite was useful as an absorbent bandage.
[0092] While the invention has been described in detail with
respect to specific embodiments thereof, and particularly by the
example described herein, it will be apparent to those skilled in
the art that various alterations, modifications and other changes
may be made without departing from the spirit and scope of the
present invention. It is therefore intended that all such
modifications, alterations and other changes be encompassed by the
claims.
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