Two-way stretchable fabric laminate and articles made from it

The invention is a stretchable layered fabric laminate which is air impermeable and waterproof while being permeable to water vapor. The stretchable fabric laminate includes a stretchable composite material layer consisting of a hydrophobic protective layer of a porous polymeric material on each side of a layer of hydrophilic water-vapor-permeable synthetic polymer. The composite material layer is laminated to at least one layer of stretchable fabric. The stretchable layered fabric laminate has excellent stretch and recovery properties in both machine and transverse directions, and is useful for the manufacture of form-fitting articles of protective clothing and other end uses.

FIELD OF THE INVENTION 
This invention relates to stretchable fabric laminates which are air 
impermeable and waterproof while being permeable to water vapor, for use 
as form-fitting articles of protective clothing and other end uses. 
BACKGROUND OF THE INVENTION 
Protective clothing articles used for wear in wet conditions (such as rain, 
snow, etc.); in outdoor activities (such as skiing, biking, hiking, etc.); 
in handling hazardous chemicals, in preventing contamination, in avoiding 
infection, should in each instance protect the wearer by preventing 
leakage of water or other fluids and microorganisms into the article while 
keeping the wearer comfortable by allowing perspiration to evaporate from 
the wearer to the outside of the article. In addition, if such an article 
is intended to be reusable, it should maintain the functional attributes 
of protection and comfort during ordinary use including automatic machine 
washing. 
In protective clothing articles where flexibility of movement is essential, 
stretchable fabric laminates with the above functional attributes are 
needed along with soft and drapeable feeling. Such stretchable fabric 
laminates are increasingly being used to make protective clothing articles 
which are form-fitting since the stretch properties of the material allow 
for a closer fit without adversely affecting the wearer's comfort. Gloves, 
mittens, socks, stockings, ski wear, running suits, athletic garments, 
medical compresses, are some examples of such articles of protective 
clothing requiring form-fitting characteristics. 
In addition to the above, the direction or directions of stretch, the 
amount of stretch and its recovery and the force exerted during recovery 
are all important properties that determine comfort of form-fitting 
articles of protective clothing as well as the method and ease of 
manufacturing them. The precise magnitude and balance of these properties 
in a stretchable fabric material, however, depend on each specific end 
use. 
A variety of laminated fabrics are known which offer stretch 
characteristics in addition to waterproofness and breathability as 
measured by their ability to pass water vapor. U.S. Pat. No. 4,935,287 
(Johnson et. al.) describes stretchable laminate constructions based on an 
elastic fabric and a substantially non-elastic film which are held in 
intimate contact with one another by means of a noncontinuous pattern of 
adhesive. When the laminate constructions of the invention are in a 
relaxed state, the length of the film between adjacent adhesion points in 
the direction of stretch of the elastic fabric is essentially equivalent 
to the length of the elastic fabric between the same adhesion points when 
the construction is extended to its elastic recovery limit. A preferred 
embodiment of the invention utilizes waterproof breathable non-elastic 
membranes to produce laminate constructions suitable for clean room and 
protective garment applications. The breathable material of this invention 
provides stretch properties only in the machine direction. 
U.S. Pat. No. 5,244,716 (Thornton et. al.) describes a composite extendable 
material useful for making a clothing article comprising a first film 
layer resistant to penetration by liquid water but permeable to water 
vapor. The first film layer is adhered at discrete securement locations to 
a second layer of water vapor permeable extendable sheet material. The 
adherence between the two layers is such that when the composite material 
is under no stretching force and resting on a flat surface the second 
layer is corrugated, ruched or puckered. The adherence is also such that 
the composite material can be stretched at least 10% in at least one 
direction by a force less than that required to stretch the material 
forming the first layer by the same amount by itself. The preferred 
material of this invention also relies on a single microporous film layer 
for breathability and waterproofness. Waterproofness of such microporous 
films are typically low and they are commonly susceptible to loss in the 
waterproofness due to contamination of the micropores by low surface 
tension liquids like oils, perspiration, etc. Also, such films are air 
permeable and are not absolute barriers because of their microporous 
nature. 
U.S. Pat. No. 4,761,324 (Rautenberg et.al.) describes a laminated elastic 
fabric which includes a layer of stretch material having substantial 
elastic qualities, a polymer film layer being breathable, water-resistant 
and having elastic qualities, and an adhesive present in substantially 
discontinuous segments bonding the film to the elastic fabric. The 
material of this invention also relies on a single layer of polymer film 
for the properties of waterproofness and breathability. If such films are 
non-porous, they must be hydrophilic for adequate breathability. In that 
case, the hydrophilic nature of the film will cause them to swell and 
weaken significantly when in contact with liquid water. As a result, such 
polymer films usually show poor durability particularly when subjected to 
repeated automatic machine washing. U.S. Pat. No. 5,036,551 (Dailey 
et.al.) describes elastomeric composite fabrics which have a layered 
construction and are made of a microporous polymeric membrane, a water 
vapor permeable polymer, and an elastomeric thermoplastic nonwoven 
material. The elastomeric composite fabric provides barrier properties 
with water vapor permeability and finds utility in articles of wearing 
apparel and other articles which conform to the wearer. The material of 
this invention may not be suitable for certain end-uses since it uses an 
elastic non-woven material as a support which is relatively weaker than 
conventional woven or knitted fabrics. Also, the nonwoven material is 
bonded by using a continuous layer of a hydrophilic polyurethane which is 
susceptible to swelling and weakening in wet environments and is likely to 
contribute to poor durability in end-uses demanding repeated exposure to 
wet environments and automatic machine wash. 
U.S. Pat. No. 4,443,511 (Worden et.al.) describes a waterproof and 
breathable elastomeric polytetrafluoroethylene layered article for use in, 
for example, material for protective articles. The waterproof and 
breathable polytetrafluoroethylene layered article can, for example, 
exhibit elastomeric properties of stretch to break of 275% in the machine 
direction and 145% in the transverse direction and a total stretch 
recovery of at least 39% after being stretched to 75% extension for 100 
cycles. The invention further provides a waterproof and breathable 
polytetrafluoroethylene layered article bonded to a stretch fabric. The 
waterproof and breathable elastomeric polytetrafluoroethylene layered 
article bonded to a stretch fabric is thus durable and possesses a water 
vapor transmission rate exceeding 1000 gms./m.sup.2 day, and preferably 
above about 2000 gms/m.sup.2 day. The material of this invention may not 
possess adequate stretch recovery properties for certain end uses. 
SUMMARY OF THE INVENTION 
It is a purpose of the present invention to provide a soft, drapeable, 
stretchable fabric laminate with novel elastic properties in both machine 
and transverse directions at low stretching force while providing the 
functional attributes of breathability, waterproofness and air 
impermeability that are durably retained over the intended life of the 
form-fitting articles of protective clothing made from the laminate for a 
particular end use. 
The purpose is accomplished herein by a stretchable layered fabric laminate 
stretchable in both the machine and transverse direction which comprises: 
(a) a composite layer comprising two layers of porous hydrophobic material 
partially impregnated with and laminated together by a continuous layer of 
an elastomeric hydrophilic water-vapor permeable polymer to form said 
composite layer having a non-porous internal region and two porous 
surfaces; 
(b) said composite layer being laminated on at least one side to a layer of 
an elastic fabric by an adhesive distributed in a non-continuous pattern 
such that the composite layer is bunched together in folds in the machine 
direction; 
said fabric laminate, in both machine and transverse directions, being 
capable of stretching at least 10% and recovering at least 80% of the 
amount stretched when the stretching force is removed, and 
said fabric laminate being air and liquid water impermeable and is water 
vapor permeable to the extent of having a water vapor transmission rate of 
at least 2000 gm./m.sup.2 /24 hrs. 
The stretchable fabric laminate of this invention has novel stretch 
properties, and can be used to provide articles of protective clothing 
which are form-fitting with protection and comfort to the user. In 
addition, the novel stretch characteristics of the stretchable fabric 
laminate of this invention also provide the advantages of conventional 
stretch fabrics such as, better fit, more shape retention, improved ease 
of movement, better wrinkle resistance, fewer sizes and alterations, and 
more design flexibility. 
Additionally, in one embodiment of the invention is provided a form-fitting 
article which comprises the stretchable fabric laminate defined above, 
said fabric laminate being joined together along the periphery thereof to 
form a configuration corresponding to the contour of a desired object, 
leaving at least one unjoined open portion. Thus, a form-fitting sock 
insert, sock, hose, stocking, sleeve, hat, glove insert, glove or mitten 
can be formed. 
As used in this application: 
By "waterproof" is meant the ability to resist penetration by liquid water 
by providing hydrostatic resistance of 6.8 kPa (1.0 psi) or more. 
By "porous" is meant a structure of interconnected pores or voids such that 
continuous passages and pathways throughout a material are provided. 
Machine direction as used herein indicates the direction of manufacture. 
Transverse direction as used herein indicates the direction in the plane 
of manufacture perpendicular to the machine direction. The materials of 
the layers described herein are considered to be planar, defined by their 
length (machine direction) and width (transverse direction). 
Percentage stretch is defined as 
EQU % Stretch=(Ls/Lo-1).times.100 
and percentage recovery is defined as 
EQU % Recovery=([Ls-Lf]/[Ls-Lo]).times.100 
where Lo is the original length, Ls is the length when a stretching force 
is applied, and Lf is the length when the stretching force is released.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention provides a stretchable fabric laminate formed of a 
composite layer bonded to at least one layer of an elastic fabric by a 
discontinuous pattern of an adhesive such that in its relaxed state the 
composite layer is bunched together in folds in the machine direction. The 
composite layer comprises two hydrophobic porous polymeric membrane layers 
partially impregnated and bonded together by a non-porous, continuous, 
water vapor permeable layer of an elastomeric hydrophilic polymer. 
The stretchable fabric laminate of the present invention is capable of 
being easily stretched simultaneously in both the machine and the 
transverse direction and also exhibits excellent recovery from stretching 
in both directions, i.e., the fabric laminate has elastic properties in 
both directions. The porous polymeric membrane layers of the composite 
layer can be inherently non-elastic and may have virtually no recovery 
properties. Also, the porous polymeric membrane layers may have relatively 
poor stretch characteristics in one or both directions which must be 
overcome. Therefore, the elastic behavior of the stretchable fabric 
laminate results from the properties of the materials with which the 
porous polymeric membrane layers are combined or from the processing 
methods used to form the stretchable fabric laminate. 
In either the machine or transverse direction the elastic properties can 
result from the material characteristics of the component layers. For 
example, from the presence of elastomeric yarns oriented generally in one 
or both directions of the knit or woven fabric forming the fabric layer, 
or from the hydrophilic elastomeric polymer forming the non-porous 
water-vapor-permeable layer of the composite layer which has generally 
isotropic elastic properties. To overcome limited stretchability or 
anisotropic stretchability of the polymeric membrane layers of the 
composite layer methods such as overfeeding, underfeeding, width control, 
and the like can be used in laminating the composite layer to the fabric 
layer. Such methods will be described in detail hereinbelow. 
The stretchable fabric laminate with one elastic fabric layer is shown 
schematically in FIGS. 1, 2 and 3, while FIGS. 4 and 5 are 
photomicrographs of the same. In FIGS. 1, 2, and 3, 1 is the porous 
hydrophobic polymer layer, 2 is the continuous non-porous hydrophilic 
water vapor permeable polymer layer, 3 is the discontinuously distributed 
adhesive, 4 is the elastic fabric, 5 is the composite layer comprising 
layers 1 and 2, and 6 represents the entire stretchable fabric laminate. 
As the schematics in FIGS. 1, 2 and 3 illustrate, the various layers are 
shown as individual layers; It is understood, however, that the moisture 
permeable polymer layer 2 penetrates partially into the pores of layers 1 
to form the composite layer 5. 
FIG. 2A and FIG. 4 show the stretchable laminate cross-section parallel to 
the machine direction in an unstretched state. In this orientation, the 
composite layer 5 assumes a bunched, rippled or puckered appearance. As 
shown in FIG. 2B, the length of the layer 5 between adjacent adhesion 
points in the machine direction is substantially equivalent to the length 
of the elastic fabric 4 between the same adhesion points when the 
stretchable laminate 6 is extended to its elastic recovery limit. The 
discontinuous adhesive pattern 3 maintains the elastic fabric 4 in 
intimate contact with the composite layer 5 which is substantially 
inelastic in the machine direction. 
FIGS. 3A and 5 illustrate the stretchable laminate cross-section parallel 
to the transverse direction in an unstretched state. In this orientation, 
the composite layer 5 is substantially planar and parallel to the elastic 
fabric layer 4. As shown in FIG. 3B, under a stretching load in the 
transverse direction, the laminate 6 stretches in the transverse direction 
due to stretching of both the composite layer 5 and the elastic fabric 4 
by the same amount between the adjacent adhesive junction points. The 
discontinuous adhesive pattern 3 maintains the elastic fabric 4 in 
intimate contact with the composite layer 5 which has elastic properties 
in the transverse direction. 
The stretchable fabric laminate of the invention can also be made with two 
layers of elastic fabric, each layer being adhesively bonded to the porous 
surface of the composite layer 5. The essential features of the laminate 
geometry remains unchanged with the composite layer being bunched or 
corrugated in the machine direction and being substantially planar in the 
transverse direction. The laminate, however, appears substantially planar 
since the bunching or wrinkling of the composite layer 5 is now covered by 
the presence of another elastic fabric layer. 
By proper selection of the materials and assembly techniques, the 
stretchable, fabric laminate of this invention yields several worthwhile 
and surprising results. 
Unlike many stretchable fabric laminates, the laminate of this invention is 
capable of stretching simultaneously in both the machine and the 
transverse direction. In particular, the laminates of the present 
invention are capable of stretching by at least 10%, preferably by at 
least 25%, and most preferably by at least 40%, of its original length in 
both the machine and transverse directions. In addition to the capability 
to stretch under a load, the laminate should also recover, in both 
directions, most of its original length when the stretching force is 
released. The laminates of this invention are capable of recovering at 
least 50%, preferably 65%, and most preferably at least 80% of the 
stretched amount. Such multi-directional stretch and recovery properties 
are of great significance in applications of these laminates as articles 
of protective clothing. In particular, the ability to stretch the laminate 
in both the machine and the transverse direction and the ability to 
recover the stretched amount allow for improved form-fitting 
characteristics of the three dimensional article made from the two 
dimensional laminate. In addition, the multi-directional stretch 
characteristics allow for other benefits like fewer size requirements, 
more design flexibility and easier assembly. In articles such as gloves or 
socks, easy donning and doffing are possible only if the fabric material 
constituting it possesses adequate multi-directional stretch properties. 
In the absence of such multi-directional stretch properties, such articles 
need to be assembled from various pieces, each oriented to provide the 
needed stretch characteristics in different directions. 
Also of great utility is the fact that the stretchable fabric laminate of 
this invention can stretch in both the machine and the transverse 
direction by application of a low amount of stretching load. This is 
defined by the stretching force which is the force required per unit width 
to elongate the laminate by a fixed amount in a particular direction. For 
example, 10% stretching force is the force per unit width required to 
stretch the laminate by 10% of its original length. The stretching force 
is an indication of the ease with which the laminate can be stretched. The 
laminates of this invention demonstrate a 10% stretching force less than 
0.15 kg/cm (0.85 pli) width, as measured by the test described herein. 
Similarly tested, the 50% stretching force of the laminates range from 
0.08-0.60 kg/cm (0.45-3.41 pli) depending on the direction of stretching. 
Due to the low stretching force required, the laminate of this invention 
demonstrates particularly soft and drapeable behavior that is desirable in 
fabric materials used for form-fitting articles of protective clothing. 
It is worthwhile to note that in considering the physical properties of 
this stretchable laminate such as softness and flexibility, and its 
stretchable characteristics, it appears that the freedom of movement is 
inherent in the entire laminate and not explained strictly by the built in 
geometry by which it is assembled nor strictly explained by any one of the 
materials of construction. For example, it is to be expected that the 
force required to stretch the laminate of this invention in the machine 
direction is substantially lower than the sum of the forces required to 
stretch the material of the composite layer and the elastic fabric layer 
(or layers) individually by the same amount in the machine direction. 
However, depending on the particular construction of the elastic fabric 
used, this is also true for the laminate stretched in the transverse 
direction, and this is unexpected. 
Having a continuous water-vapor permeable but liquid water impermeable 
polymer layer, the stretchable laminate provides a barrier to various 
sources of contamination by particulates, microorganisms or low surface 
tension liquids. This provides superior contamination protection than 
material that relies on filtration phenomena to keep out (or in) 
contaminants. The continuity of this layer can be demonstrated by the fact 
that the stretchable laminate has substantially no air permeability. This 
property is imparted to the laminate by the continuity of the hydrophilic 
polymer layer, because the porous hydrophobic polymer layers and the 
elastic fabric exhibit air flow by their nature. 
The stretchable laminate of this invention shows excellent hydrostatic 
resistance as determined using the Mullen Burst Test described 
hereinbelow. The laminate has an average burst strength of at least about 
50 psi, preferably of at least about 100 psi, and most preferably of at 
least about 150 psi. 
The stretchable laminate of this invention also has the beneficial 
functional characteristics of being water-vapor permeable. The laminate 
has a WVTR (Water vapor transmission rate) of at least 2000 g/m.sup.2 /24 
hrs, preferably greater than 4000 g/m.sup.2 /24 hrs, and most preferably 
greater than 6000 g/m.sup.2 /24 hrs, as measured by the test described 
herein. 
The stretchable laminate of this invention also provides superior wash 
durability due to the novel construction of the composite layer that 
provides the functional barrier properties of windproofness, 
waterproofness and breathability. Owing to the construction of the 
composite layer, the non-porous continuous water vapor permeable 
hydrophilic polymer layer is protected by a hydrophobic porous layer on 
each side. As a result, even in a wet environment as in actual end-use or 
in automatic machine wash; the hydrophilic polymer layer does not come in 
direct contact with liquid water which will swell the polymer excessively 
and weaken it. The weakened continuous polymer film would then be 
susceptible to failure due to generation of a variety of defects created 
by abrasion and deformation. 
Additional characteristics of this stretchable laminate are best understood 
when the laminate is converted into articles of protective clothing, for 
example, socks, gloves, sleeves, and braces. Typically, such articles can 
be formed by placing two layers of the laminate of the invention on top of 
another with the porous layers of each layer in contact with one another 
and sealing them together in the desired position to create a waterproof 
seam. Sealing can be done by the use of conventional techniques like heat 
sealing, RF sealing, ultrasonic sealing, electromagnetic welding and other 
methods known in the art. If the porous polymer layers are not amenable to 
such sealing or if the laminate comprises of two elastic fabric layers, 
articles can be formed by other methods known in the art. 
One method for manufacturing an article in the form of a sock with the 
stretchable laminate of this invention is as follows. Two layers of the 
stretchable laminate are positioned such that similar elastic fabric 
layers are adjacent to one another. These sheets of material are then cut 
into the shape of a sock using appropriate dies known in the art. The 
stitching of the two sheets is then conducted along the periphery that 
defines the contour of a foot, leaving the ankle portion unstitched. The 
stitched seam is then sealed with a water impermeable adhesive tape to 
make the entire sock waterproof. What is obtained is a substantially 
two-dimensional stretchable sock into which the foot may be inserted via 
the open ankle portion. Due to the features of the stretchable laminate 
herein, and if the die pattern has been appropriately designed and sized, 
the sock conforms to the individual's foot as it is pulled on yielding a 
three-dimensional form fitting sock. The sock exerts a gentle force on the 
foot to provide a snug comfortable fit. As such, the socks of these 
materials also are liquid water tight and are substantially air 
impermeable. This means there is exceptionally high contamination 
protection provided by the socks made from the stretchable laminate. 
Furthermore, the microclimate around the wearer's foot is maintained 
comfortable by the high moisture vapor permeability of the stretchable 
laminate. 
Another method for manufacturing an article in the form of a glove with the 
stretchable laminates of this invention is as follows. On a layer of the 
stretchable, laminate, a molten bead of a hot melt adhesive is deposited 
in the shape of the hand which is then brought in contact with another 
fabric layer, which may or may not be stretchable. The entire assembly is 
then heat sealed and trimmed to obtain the final article. The heat sealing 
creates a seam along the periphery that defines the contour of a hand, 
leaving the wrist portion unsealed. Trimming is accomplished outside this 
heat sealed bond line and in addition includes the wrist portion. What is 
obtained is a two-dimensional stretchable glove into which the hand may be 
inserted via the open wrist portion. Due to the multi-directional stretch 
characteristics of the laminates herein, and if the die pattern has been 
appropriately designed and sized, the glove conforms to the individual's 
hand as it is pulled on, yielding a three-dimensional form-fitting glove. 
Further, since the glove is constructed from the soft and drapeable 
stretchable laminate described herein, it allows for good dexterity on 
behalf of the user. Furthermore, the gloves are comfortable to the user. 
The fact that an individual can have a fabric surface against the hand is 
also an added benefit provided by the laminate of this invention. 
Because articles of the stretchable laminate herein exhibit exceptional 
contamination control, are very functional (i.e. form fitting with good 
touch and feel characteristics) and comfortable, they are particularly 
useful as articles of protective clothing, providing protection from 
influences such as outdoor weather, from contamination in clean room 
environments, from infection in medical use, from hazardous liquids in 
chemical handling. Additionally, since the articles made from the laminate 
of this invention provide a certain amount of compressive force while 
fitting a form snugly; the laminates of this invention can also be used in 
the management of wound care in various forms such as bum mittens, burn 
compresses, and the like. The compressive force exerted by an article made 
from the stretchable laminate of the invention can also be useful in 
health-care applications in the form of sleeves, braces, and liners for 
orthopaedic casts. 
The porous polymeric membrane used in this invention is a microporous 
polymer having a microscopic structure of open, interconnecting micro 
voids. It exhibits air permeability and as such imparts, or does not 
impair, water vapor permeability. The microporous membrane in the laminate 
described herein is typically of a thickness of 5 .mu.m to 125 .mu.m, most 
preferably of the order of about 5 .mu.m to 25 .mu.m. 
The microporous polymeric membrane can be inelastic in nature, but the 
essential requirement of the membrane is that it is able to elongate at 
least 50%, more preferably at least 100%, and most preferably at least 
150% in the transverse direction while retaining its liquid water 
impermeability. Such elongation properties in the machine direction of the 
microporous polymeric membrane are not essential to make the stretchable 
laminate of this invention. 
Furthermore, the microporous polymeric membranes useful herein are soft and 
flexible, either by virtue of their geometry or their chemistry or both. 
The useful polymers of the microporous membrane materials include plastic 
polymers as well as elastomeric polymers. Examples of suitable polymers 
include polyesters, polyamides, polyolefins, polyketones, polysulfones, 
polycarbonates, fluoropolymers, polyacrylates, polyurethanes, copolyether 
esters, copolyether amides and the like. The preferred polymers are 
plastic polymers. 
The preferred microporous polymeric membrane material is expanded, 
microporous polytetrafluoroethylene (PTFE). These materials are 
characterized by a multiplicity of open, interconnecting microscopic 
voids, high void volume, high strength, soft, flexible, stable chemical 
properties, high water vapor transfer, and a surface that exhibits good 
contamination control characteristics. U.S. Pat. Nos. 3,953,566 and 
4,187,390 describe the preparation of such microporous expanded 
polytetrafluoroethylene membranes and are incorporated herein by 
reference. 
It has been found that the stretch characteristics of the laminate herein 
can be controlled to a large degree by selecting the microporous expanded 
PTFE with a specific combination of properties such as weight per unit 
area, and the level of anisotropy in elongation characteristics. For the 
laminate of this invention, microporous expanded PTFE membranes with 
weights of 2 to 50 gm/m.sup.2 may be useful, but the range of 2 to 30 
gm/m.sup.2 is preferred. Moreover, if the polymeric membrane does not 
inherently possess the necessary elongation characteristics in the 
transverse direction, it is possible in some cases to develop this 
property in the membrane. For example, by stretching the membrane in the 
machine direction its width can be reduced without any substantial change 
in thickness. The membrane, so processed, can then be stretched 
transversely back to about its original width without difficulty. If the 
membrane is used to form a composite layer while the membrane width has 
been thus reduced, and the composite layer subsequently laminated to a 
fabric having elastic stretch properties in the transverse direction, 
suitable elastic properties in the transverse direction can be obtained in 
the laminate. Membranes having isotropic elongation characteristics can be 
prepared as described above, but isotropic behavior is not necessary to 
make the laminate of this invention. 
The continuous water vapor permeable polymer layer is a hydrophilic polymer 
having some elastomeric characteristics. The hydrophilic layer selectively 
transports water by diffusion, but does not support pressure driven liquid 
or air flow. Therefore, moisture i.e. water vapor, is transported but the 
continuous layer of the polymer precludes the passage of such things as 
airborne particles, microorganisms, oils, or other contaminants. This 
characteristic imparts to the elastomeric composite fabric, and in turn to 
articles made from it, such as socks and gloves, good contamination 
control characteristics by functioning as a barrier to contaminants of all 
sizes. Furthermore, the water vapor transmitting characteristics of the 
material allow for comfort characteristics to the wearer. 
The continuous water-vapor-permeable polymer layer is typically of a 
thickness of between 5 .mu.m to 50 .mu.m, preferably between about 10 
.mu.m and 25 .mu.m. This thickness has been found to be a good practical 
balance to yield satisfactory durability, continuity, and rate of water 
vapor transmission. 
Although not limited to them, the continuous, water-vapor-permeable 
polymers most useful herein are those of the polyurethane family, the 
copolyetherester family, or the copolyetherester amide family. Suitable 
copolyether ester hydrophilic compositions may be found in the teachings 
of U.S. Pat. No. 4,493,870 to Vrouenraets and U.S. Pat. No. 4,725,481 to 
Ostapacihenko. Suitable hydrophilic copolyetherester amide compositions 
are described in U.S. Pat. No. 4,230,838 to Foy et.al. Suitable 
polyurethanes may be found by way of example in the teachings of U.S. Pat. 
No. 4,194,041 to Gore. A preferred class of continuous, water vapor 
permeable polymers are polyurethanes, especially those containing 
oxyethylene units, such as are described in U.S. Pat. No. 4,532,316 to 
Henn, incorporated herein by reference. Typically these materials comprise 
a composition having a high concentration of oxyethylene units to impart 
hydrophilicity to the polymer, The concentration of oxyethylene units is 
typically greater than 45% by weight of the base polymer, preferably 
greater than 60%, most preferably greater than 70%. 
Because the continuous water vapor permeable layer is not directly exposed, 
but is protected by the porous hydrophobic membrane layer, in the 
stretchable composite fabric of this invention, the hydrophilicity does 
not need to be compromised as it has in many prior art fabrics. Preferably 
materials are selected so that the water vapor permeability of each is at 
its maximum. As such the continuous permeable polymer layer can frequently 
be found to be the limiting link in the water vapor permeability of the 
fabric. Part of the inventiveness herein is the ability to be able to 
maximize the water vapor permeability without tradeoffs to the final 
stretchable laminate's contamination control and stretch properties. 
The composite layer 5 used to make the stretchable laminate of this 
invention can be prepared according to the teachings of U.S. Pat. No. 
5,026,591 to Henn et.al, incorporated herein by reference. The method is 
illustrated but not limited to the following description of a four roll 
stack as shown in FIG. 6. Metered control of the molten water vapor 
permeable polymer is provided for by a gravure roll 7 and doctor 
blade/polymer reservoir 8. The water vapor permeable polymer 9 is applied 
as a thin, continuous, liquid film to the continuously moving porous 
polymeric membrane 10 in the nip between two rotating rolls 11, 12; one 
such rotating roll 11 having been coated with the liquid polymer and the 
other such roll 12 providing support so as to force the polymer partially 
into the porous structure of the membrane 10. The composite 13 is 
subsequently combined with another porous polymer layer 14 in the nip 
between two rotating rolls 12, 15, resulting in the composite layer 5 used 
in this invention. 
A wide variety of elastic fabrics 4 can be utilized in the stretchable 
laminate of this invention; however, such elastic fabrics should not make 
the final stretchable laminate so stiff so as to offer excessive 
resistance to body movements or to reduce its form-fitting 
characteristics. 
The elastic fabric should be able to stretch easily in both the machine and 
the transverse direction. It is, however, not necessary that these fabrics 
have similar elastic properties in both the directions. It has been 
determined that the elastic fabric should be capable of stretching at 
least 10%, more preferably at least 50%, and most preferably at least 100% 
in both directions. 
Elastic fabrics usable in the stretchable laminate constructions of the 
present invention include woven, non-woven or knitted fabrics. The elastic 
fabrics are typically composed of a hard or non-elastomeric fiber and an 
elastic fiber. Suitable hard fibers include synthetic fibers such as 
nylon, polyester or polypropylene fibers or naturally occurring fibers 
such as cotton. Suitable elastic fibers include polyurethane block 
copolymer based fibers as described in U.S. Pat. No. 2,692,873 and sold as 
Lycra.TM. or Spandex fibers. 
Knitted fabrics are preferred as the elastic fabrics used in the 
stretchable laminate of the present invention. Such elastic knitted 
fabrics are typically composed of a hard fiber yarn that is 
non-elastomeric and an elastomeric Lycra.TM. or Spandex yarn. The knit has 
elastic characteristics by virtue of the structure of the knit and its 
elastomeric fiber content. More specifically, knitted fabrics having 5 to 
20% elastomeric fiber content and from 95 to 80% hard fibers have been 
found to be very useful. Warshow Style 3320 knitted fabric having 80% of 
nylon 6,6 fiber and 20% of Lycra.TM. fiber with a machine 
direction/transverse direction elongation of 414%.times.219% is a typical 
example of an elastic fabric suitable for the stretchable laminates of 
this invention. 
The technique for laminating the composite layer 5 to an elastic fabric 4 
is of great importance to the resultant stretch characteristics of the 
stretchable laminate 6. A wide range of adhesives can be used to bond the 
composite layer to a layer of an elastic fabric. 
The adhesive can be applied to either component to be bonded in the form of 
powder, hot melt, reactive hot melt, solution or dispersions, or 
discontinuous net-like sheet. 
The adhesive can be of any type, e.g. one forming a bond by solvent 
evaporation or by coalescence from a dispersion, with or without exposure 
to heat, or one functioning by a thermoplastic (e.g. hot melt) mechanism, 
but is preferably of a type which is crosslinkable, or curable, usually 
upon activation by heat; the cross-linkable nature being an advantage from 
the standpoint of enhanced resistance to exposure to heat and prolonged 
contact with water, e.g. on washing. 
Crosslinkable polyurethane adhesives are known to give satisfactory 
results. Such adhesives are commercially available in various forms; as an 
aqueous dispersion, as a solution in organic solvents, as a powder or 
solid chip to be used as a hot melt composition or be first dissolved in 
organic solvents, or as a discontinuous net-like sheet or non-woven web. 
Adhesives in form of an aqueous dispersion or an organic solvent solution, 
e.g. polyurethane prepolymers, are frequently hydroxyl- or hydroxyl- and 
carboxyl-terminated and are blended with a crosslinking agent shortly 
prior to use. The crosslinking agent may be e.g. aziridine (ethylene 
imine), a substituted aziridine, a polyfunctional isocyanate prepolymer, a 
melamine- or urea-formaldehyde resin, or an epoxy composition. 
Adhesives in the form of powder or sheet are frequently supplied already 
compounded with the crosslinking agent but have adequate stability at 
ambient temperature. 
The blended adhesive is typically applied to one or both layers to be 
bonded at a dry weight of 5 to 50 grams per square meter. The method of 
application depends on the form in which the adhesive is used and can be 
e.g., sprinkling for a powder; but spraying or gravure printing are 
preferred for a liquid, hot melt or reactive hot melt adhesive. 
Regardless of the adhesive system, it is important that the adhesive 
provides high green strength and that it is capable of resisting wet 
environments. 
A preferred adhesive system is a carbamate/urethane composition as 
described in U.S. Pat. No. 5,209,969 to Crowther, incorporated herein by 
reference. This is a storage stable adhesive mixture of 
hexamethylenediamine carbamate and the reaction product of 
ethylene/propylene oxide polyol and a polyurethane prepolymer of 
diphenylmethane diisocyanate, polytetramethylene glycol, and optionally, 
1,4-butanediol. Under ambient conditions, the adhesive is a viscous liquid 
of about 2000 poise viscosity which becomes a liquid of about 300 poise 
viscosity when heated to 50.degree. C. The adhesive typically requires a 
cure time of several minutes at 140.degree. C., but the cure time can be 
significantly reduced by increasing the cure temperature to greater than 
160.degree. C. 
It is important that the a minimal amount of adhesive 3 be used in bonding 
the composite layer 5 to the elastic fabric 4. Adhesive can be applied to 
the composite layer or the elastic fabric such that it covers less than 
about 70%, more preferably less than about 50% and most preferably less 
than about 40% of the surface of the composite layer on the fabric. It is 
preferred that the adhesive be applied to the composite layer. The 
adhesive add-on weights can range from 5 gm/m.sup.2 to 50 gm/m.sup.2, with 
the preferred add-on weights ranging from 5 gm/m.sup.2 to 30 gm/m.sup.2. 
The adhesive coverage can be adjusted over the indicated range to provide 
a stretchable laminate with specific performance requirements for a given 
application. 
The adhesive can be applied using a variety of contact and non-contact 
techniques. Gravure printing and screen printing are typical contact 
techniques; whereas spraying and melt blowing are examples of non-contact 
techniques for adhesives that are applied in form of a liquid. In cases of 
adhesive in the form of a web, such application techniques are not needed 
since the adhesive already has been preformed in the form of a continuous 
porous web with built in discrete openings in the plane of the web. 
The process used to prepare the stretchable laminate of this invention can 
be better understood with reference to FIG. 7 which is a schematic 
illustration of a preferred process. 
In the process, a dot pattern of heat-curing adhesive is metered onto one 
of the porous surfaces of the composite layer 5 by a gravure roll 16 in 
such a manner as to provide coverage of approximately 33% of the porous 
surface. The doctor knife/adhesive reservoir 17 and the gravure roll 16 
are heated to about 50.degree. C. The composite layer is held under 
minimal tension against the gravure roll by a low durometer rubber roll 18 
at a pressure sufficient to effect removal of the adhesive dots onto the 
porous surface of the composite layer 5. 
On exiting the printing nip 19 the adhesive dot coated composite layer 20 
is brought to the laminating roll 21 where it is brought in intimate 
contact with the elastic fabric 4 being held in a stretched state by 
ensuring that the speed of the exit nip 22 is higher than that of the feed 
roll 23. Control of the stretch of the elastic fabric 4 at this stage of 
the process is critical as the stretch properties of the final laminate in 
the machine direction will depend on it. Typically the fabric is stretched 
in the machine direction such that its width is reduced to about 50% to 
90% of its initial width. If the elongation of the elastic fabric is too 
low, the stretch properties of the resulting laminate will be low and the 
stretching force will be high in the machine direction. Excessive 
elongation of the elastic fabric, however, must be avoided since this may 
lead to inelastic deformation of the fabric in the machine direction. 
The laminate 24 created by the uncured adhesive is then wrapped around a 
roll 25 and heated to a temperature suitable for curing the adhesive. 
During this curing stage, the laminate is held under tension against the 
heated roll 25 and the curing time is controlled by the degree of wrap 
around this roll as well as the speed at the exit nip 22. The exit nip is 
formed by a rubber roll 26 exerting pressure against the heated roll 25 
while being maintained at ambient temperature. During this curing stage, 
it is preferred that the composite layer of the laminate 24 is in contact 
with the hot roll and that the tension of the laminate between the roll 21 
and nip 22 is the same as that of the elastic fabric between the feed roll 
23 and the nip 27. 
Upon exiting nip 22, the final laminate 6 is immediately allowed to relax 
by taking it up on a roll 28 while maintaining the laminate under no 
tension. Allowing the laminate to cool in a relaxed state is critical in 
maintaining the machine direction stretch properties of the laminate of 
this invention. If the laminate is taken up under tension, the stretch 
properties of the laminate are adversely affected due to deterioration of 
the stretch characteristics of the elastic fabric. 
A stretchable laminate with two elastic fabric layers can also be made by 
laminating an elastic fabric layer to the porous surface of the 
stretchable laminate 6 using the preferred lamination process described 
above. In this case, the adhesive is printed in a dot pattern on the 
porous side of the stretchable laminate 6 and is laminated to the second 
elastic fabric using the same procedure described above. Prior to printing 
of the adhesive, the stretchable laminate 6 should be stretched such that 
the porous surface becomes substantially flat. Alternatively, it is also 
possible to use a moisture curing adhesive such as a polyurethane adhesive 
described in U.S. Pat. No. 4,532,316 to Henn. In this case, the heated 
roll 25 can be maintained at a lower temperature such that the final 
laminate can be taken up under high tension to hold the laminate in a 
stretched state while the adhesive is allowed to cure by slowly reacting 
with ambient moisture. 
In addition to the preferred process, the stretchable laminate can also be 
produced by different techniques depending on the form and nature of the 
adhesive used. It is key, however, that the adhesive is capable of bonding 
the composite layer to the stretched elastic fabric such that the adhesive 
junctions are not disturbed when the laminate is returned to the relaxed 
state. This can be achieved in different ways. The preferred process uses 
thermal activation of the adhesive. Alternatively, cooling of a 
thermoplastic adhesive may be used to create such adhesive junctions. 
Another alternative is to use a high green strength thermosetting adhesive 
to create such adhesive junctions which are then subsequently reacted for 
added adhesive strength. U.S. Pat. No. 4,820,368 to Markera et.al. 
describes a class of such high green strength reactive hot melt adhesives. 
Test Procedures 
A variety of different tests have been used in the examples to demonstrate 
the various functional characteristics of the fabric laminates. 
Gurley Number Determination 
The microporous membrane and the composite layer were tested for air 
permeability. The results are reported as Gurley Numbers, defined herein 
as the time in seconds for 100 cc of air to flow through 6.45 cm.sup.2 of 
test material under a pressure drop of 1.2 kPa. The test device, a Gurley 
Densometer Model 4110, was employed in a method similar to Method A of 
ASTM D726-58. The sample was clamped into the testing device with a 
reinforcing mesh screen (150 microns) under the test sample to prevent 
rupture of the test sample,. Three test samples were employed. If no air 
flow was detected for 5 minutes, the sample is considered to be air 
impermeable. 
Moisture Vapor Transmission Test 
A description of the test employed to measure water vapor transmission rate 
(WVTR) is given below. The procedure has been found to be suitable for 
testing fabric laminates with high transmission rates. 
In this procedure, approximately 70 mls of a saturated salt solution of 
potassium acetate and distilled water was placed into a 133 mls 
polypropylene cup, having an inside diameter of 6.5 cm at the mouth. An 
expanded PTFE membrane, having a Gurley number of about 7 seconds, a 
bubble point of about 179 kPa, thickness of about 37 microns and a weight 
of about 20 gms/m.sup.2, available from W. L. Gore & Associates of Newark, 
Del., was heat sealed to the lip of the cup to create a taut, leakproof, 
microporous barrier containing the salt solution. A similar expanded PTFE 
membrane was mounted taut on the surface of a water bath while ensuring 
that the membrane is in contact with the water in the bath. The water bath 
assembly was controlled at 23.degree. C., plus or minus 0.2.degree. C., 
utilizing a temperature controlled room and a water circulating bath. 
The area for testing WVTR was 7.5 cm diameter and the sample was 
equilibrated in a chamber having a relative humidity of about 50 percent 
for a minimum of 4 hours. The sample was then placed on the surface of the 
expanded PTFE membrane covering the water bath. 
The cup assembly was weighed to the nearest 1/1000 gm and was placed in an 
inverted manner onto the center of the test sample. 
Water transport was provided by the driving force between the water and the 
saturated salt solution providing water flux by diffusion in that 
direction. The sample was tested for 15 minutes and the cup assembly was 
then removed, weighed again to within 1/1000 gm. 
The WVTR of the sample was calculated from the weight gain of the cup 
assembly and was expressed in grams of water per square meter of sample 
surface area per 24 hours. 
Mullen Burst Test 
The stretchable fabric laminates were evaluated for waterproofness by the 
Mullen Burst Test (Federal Standard 191, Method 5512). This test involves 
applying a hydrostatic force to the material under test and is used to 
determine the burst pressure of the laminate, or the pressure at which the 
laminate of the invention begins to leak. 
Laminates having a single layer of elastic fabric were mounted in the test 
apparatus with the elastic fabric on the low pressure side and the 
composite layer facing the high pressure side. In the case of laminates 
with two elastic fabric layers, the side with the lighter weight fabric 
faced the high pressure side. A woven taffeta fabric was used on top of 
the sample (low pressure side) to prevent excessive stretching of the 
sample. 
Tensile Properties 
The tensile properties of the materials were determined using ASTM D882-83 
Method A. A constant rate-of-jaw separation type machine (Instron testing 
machine) was used to perform these tests. 
Materials were cut using a die into appropriate sizes (1".times.at least 3" 
for porous membranes and composite layer samples, 1".times.3" for laminate 
samples) in both the machine and the transverse direction. Samples were 
allowed to condition in a controlled room at a temperature of 21.degree. 
C. and 65% relative humidity. 
The gauge length of the test was 1 inch and the strain rate employed was 10 
inches/min. All samples were tested till break. 
Force and strain were recorded until the sample broke. The maximum force, 
the strain at break and the forces at 10%, 25% and 50% strain were then 
noted. The average values of 5 specimens are reported directly without 
normalization to the unit area. These values therefore characterize the 
stretchable laminate. 
IP4 Stretch and Recovery 
The stretch and recovery of the stretchable laminates of this invention 
were determined as per the IP4 method at a specified load using an Instron 
tensile testing machine. 
Three separate 3".times.8" specimens were die cut from the sample laminate 
in both the machine and the transverse direction. Samples were allowed to 
condition in a controlled room at a temperature of 21.degree. C. and 65% 
relative humidity. 
The Instron machine is equipped with a 3".times.1" jaw on the bottom grip 
and a C-hook type jaw on the top grip. The sample with the 8" side aligned 
with the test direction is looped around the C-hook and both its ends are 
clamped on the 3".times.1" jaw while maintaining a gauge length of 3 
inches. The sample is then elongated at a speed of 5 inches/min. until the 
force reaches a preselected load. The sample is then brought to its 
relaxed state by returning the top grip to its original gauge length. This 
cycle is repeated two more times. During the third elongation, the amount 
of stretch to reach the preselected force is recorded. Then, the recovery 
is obtained from the specimen length, l, at which the force first becomes 
zero. 
EQU % Recovery=(2-l/3).times.100 
Tests were done with a preselected load of 4 lbs. and 12 lbs., and the data 
are designated by the suffixes IP4 (4 lbs.) and IP4 (12 lbs.). 
Liquid Water Leakage 
Articles made from the stretchable laminates were tested to determine 
whether materials and the articles produced from these materials would be 
an effective barrier. An effective barrier is defined as the ability of a 
material to prevent the passage of liquid water under the conditions of 
this test. 
400 ml. of water was carefully poured into the article through the open 
portion of the article. The article was held in an inverted position so to 
contain the water throughout the duration of the test. The outside surface 
and the seam of the article were observed for one minute or until the 
presence of water leakage was observed. 
If any water leakage from the article was observed, the article would 
receive a fail rating. If no water leakage from the article was observed 
during the one minute test period the article would receive a pass rating. 
Automatic Home Laundering 
The stretchable laminates were tested to assess their suitability for use 
in automatic home laundering. AATCC Method 135-1987 was used for this 
test. The result is reported as the number of wash-dry cycles before the 
sample loses its waterproofness as determined by the Waterproofness Test 
described below. 
Waterproofness Test 
Samples of materials are tested for waterproofness by using a modified 
Suter test method, which is a low water-entry-pressure challenge. The test 
consists essentially of forcing water against one side of a test piece, 
and observing the other side of the test piece for indications of water 
penetration through it. 
The sample to be tested is clamped and sealed between rubber gaskets in a 
fixture that holds the test piece inclined from the horizontal. The outer 
surface of the test piece faces upward and is open to the atmosphere, and 
to close observation. Air is removed from inside the fixture and pressure 
is applied to the inside surface of the test piece, over an area of 7.62 
cm (3.0 inches) diameter, as water is forced against it. The water 
pressure on the test piece is increased to 6.8 kPa (1.0 psi) by a pump 
connected to a water reservoir, as indicated by an appropriate gauge and 
regulated by an in-line valve. 
The outer surface of the test piece is watched closely for the appearance 
of any water forced through the material. Water seen on the surface is 
interpreted as a leak. A sample achieves a passing grade when, after 3 
minutes, no water is visible on the surface. Passing this test is the 
definition of "waterproof" as used herein. 
The following examples illustrate embodiments of the invention, but are not 
intended to limit the scope of the present invention. 
Example 1 
This example demonstrates a two step method to produce the stretchable 
laminate of this invention. In the first step, a composite layer, 
designated as A, was produced. This is layer 5 in FIG. 1. The two 
hydrophobic polymer layers of the composite layer A were microporous 
membrane of expanded polytetrafluoroethylene obtained from W. L. Gore & 
Associates, Inc., Elkton, Md. 
The microporous membrane was tested prior to assembly of the composite 
layer and the results of those tests are found in Table 1, column 1. 
The composite layer A was prepared by the process shown in FIG. 6 and as 
generally taught by teachings of U.S. Pat. No. 5,026,591 to Henn et.al. 
The continuous water vapor permeable polymer layer employed was a 
polyoxyethylene polyether polyurethane made according to the teachings of 
U.S. Pat. No. 4,532,316 to Henn. A roll/coater having a 4-roll stack 
configuration was used. The stack consisted of a gravure roll with a 
pattern of 110 pyramidal cells per linear inch and a cell depth of 112 
micrometers nipped at 272 psi against a low durometer silicone 
rubber-surfaced roll (surface hardness-Shore A 60 durometer), nipped at 
442 psi against a chrome-surfaced metal roll, nipped at 590 psi against a 
silicone rubber-surfaced roll (surface hardness-Shore A 60 durometer). The 
gravure roll was heated to 105.degree.-110.degree. C. The chrome roll was 
heated to 105.degree. C.-110.degree. C. The rubber rolls were at a 
temperature of about 85.degree. to 90.degree. C. The gravure roll was in 
contact with a trough containing the polyurethane in a molten state. The 
polyurethane was transferred from the gravure roll along the stack until 
it came in contact with the microporous polytetrafluoroethylene membrane. 
The polyurethane was coated on and partially forced into the microporous 
polytetrafluoroethylene membrane and formed a continuous non-porous 
coating on the polytetrafiuoroethylene membrane. A second microporous 
polytetrafluoroethylene membrane was adhered to the coated side by the 
non-porous continuous film of polyurethane thus forming composite layer A 
having two porous outer surfaces and a continuous non-porous interior. The 
microporous polytetrafluoroethylene membranes were joined with minimal 
back tension while the materials were being fed through the 4-roll stack 
at a speed of about 100 ft/min. 
The composite layer was allowed to moisture cure for about 48 hours prior 
to testing and the test results of the composite layer A can be found in 
column 2 of Table 1. 
In the second step, the composite layer A was adhesively laminated to an 
elastic fabric I. The elastic fabric I was a 1.8 oz/yd.sup.2 80/20 
Nylon/Lycra.TM. knitted fabric (Style 3320 from Warshow & Sons). The 
elastic fabric I was also tested prior to lamination and the test results 
are found in Table 1, column 3. The adhesive used was a one-component 
heat-curable polyurethane composition as described in U.S. Pat. No. 
5,209,969 to Crowther. 
The stretchable fabric laminate Z was prepared by a lamination process as 
shown in FIG. 7 using a conventional, direct gravure printer. A dot 
pattern of adhesive was metered onto one of the microporous surfaces of 
the composite layer A by a gravure roll in such a manner as to provide 
coverage of approximately 33% of the microporous surface and an adhesive 
laydown of about 5-8 gm/m.sup.2. The gravure roll was heated to 50.degree. 
C. The composite layer A was held under minimal tension against the 
gravure roll by a low durometer rubber roller at 69.4 psi pressure to 
print the adhesive dots onto the microporous polytetrafluoroethylene 
membrane surface. The printed surface of the composite layer was then 
bonded to an elastic fabric layer which had been stretched in the machine 
direction to reduce the width to about 70% of the width of the fabric in 
the relaxed state. The laminate was then wrapped around a 6 inch chrome 
roll heated at 180.degree. C. to cure the heat-curable polyurethane 
adhesive while maintaining the microporous polytetrafiuoroethylene surface 
of the laminate in contact with the chrome roll. About 65% of the hot 
chrome roll surface was covered by the laminate which was held under 
tension against the hot chrome roll and moved at 10 ft/min through the nip 
created by a low durometer rubber roll at ambient temperature being 
pressed against the chrome roll at 69.4 psi pressure. As soon as the 
laminate exited the nip the laminate was allowed to cool in the relaxed 
state in an accumulator prior to taking it up. 
The above stretchable laminate Z has one fabric surface and one microporous 
surface and the test results of this laminate can be found in column 4 of 
Table 1. In addition, the laminate Z was found to be waterproof after 77 
automatic home laundering cycles. 
Comparative Example 1 
Comparative Example 1 demonstrates the effectiveness of the lamination 
procedure of this invention. A stretchable laminate was prepared by 
laminating elastic fabric I to the composite layer A. The procedure used 
was the same as the lamination procedure described in Example 1 with the 
exception that after exiting the hot nip the laminate was not allowed to 
relax and was taken up on the take-up roll 28 under tension, The 
properties of this laminate are compared to that of the stretchable 
laminate Z in Table 2. The comparative laminate shows inferior stretch 
properties in the machine direction. 
Example 2 
This example prepares a stretchable fabric of this invention having two 
elastic fabric layers that were produced by adhesively bonding another 
layer of the elastic fabric I to the other microporous surface of 
composite layer A of the stretchable laminate Z. The lamination procedure 
and materials are the same as in Example 1 except that the adhesive was 
printed on the microporous surface of the stretchable laminate Z which was 
stretched in the machine direction to ensure that the microporous surface 
was substantially flat, and that the elastic fabric layer of the 
stretchable laminate Z of Example 1 was in contact with the hot chrome 
roll. The results of the stretchable laminate of this example are found in 
Table 3. The laminate retained its waterproofness over 105 cycles of 
automatic home laundering. 
Example 3 
A stretchable laminate with two elastic fabric layers was made by 
adhesively bonding another layer of elastic fabric I to the microporous 
side of the stretchable laminate Z using a dot pattern of a moisture 
curing, hot melt polyurethane adhesive. The adhesive used and the 
lamination procedure followed were similar to that described in Examples 1 
and 6 of U.S. Pat. No. 4,532,316 to Henn with the exception that the 
adhesive is printed on the microporous surface of the stretchable laminate 
Z stretched in the machine direction to ensure that the microporous 
surface of the stretchable laminate Z was substantially flat and it was 
bonded to a layer of elastic fabric I also stretched in the machine 
direction as in Example 1. The laminate was then taken up under adequate 
tension to maintain the laminate in a stretched state while the adhesive 
cured by reaction with ambient moisture. The results of the stretchable 
laminate of this example are found in Table 3. 
Example 4 
An composite layer B was prepared as described for preparation of Layer A 
in Example 1 except that a gravure roll having a pattern of 35 cells per 
inch and a cell depth of 206 micrometers was used. The properties of the 
composite layer B are found in Table 4. 
A stretchable laminate Y was prepared by laminating a layer of elastic 
fabric I to the composite layer B using the lamination procedure described 
in Example 1. The properties of this laminate are found in Table 4. The 
laminate retained its waterproofness for at least 100 cycles of automatic 
home laundering. 
Comparative Example 2 
Comparative Example 2 characterizes a fabric laminate made with the same 
composite layer and elastic fabric layer as described in Example 4, but 
was assembled as per the teachings of U.S. Pat. No. 5,026,591 to Henn. The 
composite layer B was bonded to elastic fabric layer I by coating and 
partially penetrating one of the porous layers of the composite layer B 
with a continuous water vapor permeable polyurethane polymer layer which 
also served as the adhesive that bonds composite layer B to the elastic 
fabric. In Table 4, the properties of this laminate are compared with that 
of the stretchable laminate Y of this invention described in Example 4. 
The comparative laminate shows inferior stretch properties in both the 
machine and transverse direction and shows that non-continuous adhesive is 
needed. 
Example 5 
A stretchable laminate X was prepared by laminating an elastic fabric II 
(3.2 oz/yd.sup.2, 80/20 Nylon/Lycra.TM. knitted fabric, style 3271 from 
Warshow & Sons) to the composite layer B using the method described in 
Example 1. The properties of the elastic fabric II as well as that of 
laminate X are found in Table 5. The laminate retained its waterproofness 
for at least 80 cycles of automatic home laundering. 
Example 6 
A stretchable laminate was prepared by laminating another layer of elastic 
fabric I to the other microporous polytetrafluoroethylene surface of 
composite layer B of laminate Y using the procedure described in Example 
2. The properties of this laminate are provided in Table 5. The laminate 
retained its waterproofness for at least 100 cycles of automatic home 
laundering. 
Example 7 
A stretchable laminate was prepared by laminating a layer of elastic fabric 
I to the other microporous surface of the composite layer B of laminate X 
using the procedure described in Example 2. The properties of this 
laminate are listed in Table 5. The laminate retained its waterproofness 
for at least 80 cycles of automatic home laundering. 
Example 8 
This example demonstrates the method to modify an existing porous polymer 
membrane and its use to make the stretchable laminate of this invention. A 
microporous expanded polytetrafiuoroethylene membrane prepared according 
to the teachings of U.S. Pat. No. 3,953,566 to Gore was used and its 
properties are listed in Table 6. Using a two-roll arrangement with the 
takeup moving at a faster rotational speed than the payoff, a 32 inch web 
of the microporous membrane was stretched in the machine direction to 
reduce the width of the web to 16 inches. The properties of the stretched 
microporous membrane are listed in Table 6, column 2. 
Two lengths of the stretched microporous membrane were used to make the 
composite layer C using the procedure described in Example 1, except that 
the roll/coater stack consisted of a gravure roll with a pattern of 85 
quadrangular cells per linear inch and a cell depth of 110 micrometers 
nipped at 69.4 psi against a silicone rubber-surfaced roll (surface 
hardness-Shore A 60 durometer), nipped at 69.4 psi against a 
chrome-surfaced metal roll, nipped at 69.4 psi against a low durometer 
silicone rubber-surfaced roll (surface hardness-Shore A 60 durometer). As 
in Example 1, the gravure roll was heated to 105.degree.-110.degree. C., 
the chrome roll was heated to 105.degree. C.-110.degree. C., and the 
rubber rolls were at a temperature of about 85.degree. to 90.degree. C. 
The gravure roll was in contact with a trough containing the polyurethane 
in a molten state. The polyurethane was transferred from the gravure roll 
along the stack until it came in contact with the microporous polymeric 
membrane. The polyurethane was coated on and partially forced into the 
microporous polymer membrane. The coated microporous 
polytetrafluoroethylene membrane was combined with a second microporous 
polytetrafluoroethylene membrane to form the composite layer A. The two 
layers of the microporous membranes were joined with minimal back tension 
while the materials were being fed through the 4-roll stack at a speed of 
about 10 ft/min. 
The composite layer was allowed to moisture cure for about 48 hours prior 
to testing and the test results of the composite layer C can be found in 
column 3 of Table 6. 
Using the lamination procedure described in Example 1, the composite layer 
C was then laminated to elastic fabric layer I to produce the stretchable 
laminate V of this invention. The properties of the stretchable laminate V 
are found in Table 6, column 4. 
Example 9 
A stretchable laminate with two elastic fabric layers was produced by 
laminating another layer of the elastic fabric I to the exposed 
microporous layer of the stretchable laminate V using the procedure 
described in Example 2. The properties of the stretchable laminate are 
provided in Table 7, column 1. 
Example 10 
This example demonstrates a stretchable laminate of the invention using two 
elastic fabrics with substantially different stretch characteristics. In 
this case, an elastic fabric III (7.8 oz/yd.sup.2, 93/7 polyester/Spandex, 
style 5418 knitted fabric from Milliken Co.) was laminated to the exposed 
microporous surface of stretchable laminate V using the procedure 
described in Example 2. The properties of the elastic fabric III as well 
as that of the stretchable laminate are respectively provided in columns 2 
and 3 of Table 7. 
Example 11 
Example 11 describes a sock manufactured from the stretchable laminate of 
Example 10. Two layers of the laminates were positioned such that the 
heavier weight elastic fabric III of the two laminates are adjacent to one 
another. Both the layers were then cut into a sock pattern designed to fit 
a foot of sizes 81/2-10 (U.S. shoe sizes). The two layers in the shape of 
a sock are stitched together while keeping the elastic fabric layers III 
adjacent to one another and keeping the ankle portion open. The stitched 
seam is then made, waterproof by heat sealing a 7/8 inch wide seam-sealing 
tape (GORE-TEX.RTM. Seam-Seal Tape, available from W. L. Gore & 
Associates, Inc., Elkton, Md.) consisting of a 6 mil (150 micrometers) 
thick layer of thermoplastic adhesive adhered to a waterproof fabric 
laminate. The adhesive was in contact with the lighter weight elastic 
fabric I. The sock was then turned inside out to have the elastic fabric 
layer III on the outside. Finally, an elastic cuff is stitched to the open 
ankle area to make the sock in its final form. 
The sock could be donned and doffed easily by a person with a shoe size of 
U.S. 91/2. When worn, the sock provided a snug, comfortable fit to the 
person's foot. 
The sock produced from this process was subjected to the liquid water 
leakage test, to determine the integrity of the stretchable fabric 
laminate and the sealed seams. The sock received a pass rating. 
TABLE 1 
__________________________________________________________________________ 
Microporous 
Membrane, 
Composite 
Elastic 
Laminate Z 
Example 1 
Layer A 
Fabric I 
Example 1 
__________________________________________________________________________ 
Weight, g/m.sup.2 
3.55 17.86 56.2 87.19 
WVTR, g/m2/24 hrs 
88,605 23,746 41,209 
18,277 
Gurley No., secs. 
2.7 impermeable 
-- -- 
Mullen Burst Press., psi 
58 158 -- 178 
Machine Direction 
% Stretch, IP4 - 4 lb 
-- 7 157 46 
% Recovery -- 98 96 98 
% Stretch, IP4 - 12 lb 
-- 25 236 86 
% Recovery -- 95 92 94 
10% Stretch Force, lbs 
0.192 0.79 0.038 0.05 
25% Stretch Force, lbs 
0.712 2.138 0.114 0.13 
50% Stretch Force, lbs 
-- Break 0.244 0.449 
Maximum Load, lbs 
1.14 2.55 10.72 13.05 
Elongation at Break, % 
52.7 78 408 327 
Transverse Direction 
% Stretch, IP4 - (4 lbs) 
-- 164 26 24 
% Recovery -- 86 99 98 
% Stretch, IP4 - (12 lbs) 
-- Break 46 81 
% Recovery -- -- 97 82 
10% Stretch Force, lbs 
0.036 0.095 0.305 0.186 
25% Stretch Force, lbs 
0.121 0.232 1.151 0.600 
50% Stretch Force, lbs 
0.257 0.403 3.388 1.512 
Maximum Load, lbs 
0.606 1.272 20.95 20.59 
Elongation at Break, % 
170 294 168 309 
__________________________________________________________________________ 
TABLE 2 
______________________________________ 
Laminate Z, 
Comparative 
Example 1 
Example 1 
______________________________________ 
Weight, g/m.sup.2 
87.19 85.25 
WVTR, g/m2/24 hrs 
18,277 16,121 
Mullen Burst Press., psi 
178 178 
Machine Direction 
% Stretch, IP4 - 4 lb 
24 -- 
% Recovery 98 -- 
% Stretch, IP4 - 12 lb 
81 53 
% Recovery 82 53 
10% Stretch Force, lbs 
0.050 0.137 
25% Stretch Force, lbs 
0.136 0.469 
50% Stretch Force, lbs 
0.449 2.649 
Maximum Load, lbs 
13.05 24.68 
Elongation at Break, % 
327 361 
Transverse Direction 
% Stretch, IP4 - (4 lbs) 
24 -- 
% Recovery 98 -- 
% Stretch, IP4 - (12 lbs) 
81 53 
% Recovery 82 89 
10% Stretch Force, lbs 
0.186 0.528 
25% Stretch Force, lbs 
0.6 1.953 
50% Stretch Force, lbs 
1.512 4.89 
Maximum Load, lbs 
20.59 29.19 
Elongation at Break, % 
309 213 
______________________________________ 
TABLE 3 
______________________________________ 
Example 2 
Example 3 
______________________________________ 
Weight, g/m.sup.2 159.8 173.1 
WVTR, g/m2/24 hrs 10,774 9,738 
Mullen Burst Press., psi 
181 180 
Machine Direction 
% Stretch, IP4 - 4 lb 
49 48 
% Recovery 98 99 
% Stretch, IP4 - 12 lb 
68 69 
% Recovery 96 98 
10% Stretch Force, lbs 
0.092 0.177 
25% Stretch Force, lbs 
0.236 0.371 
50% Stretch Force, lbs 
0.882 0.889 
Maximum Load, lbs 29.29 31.77 
Elongation at Break, % 
361 404 
Transverse Direction 
% Stretch, IP4 - (4 lbs) 
15 20 
% Recovery 98 99 
% Stretch, IP4 - (12 lbs) 
42 49 
% Recovery 93 89 
10% Stretch Force, lbs 
0.357 0.347 
25% Stretch Force, lbs 
1.26 1.007 
50% Stretch Force, lbs 
2.898 2.555 
Maximum Load, lbs 29.80 35.92 
Elongation at Break, % 
295 320 
______________________________________ 
TABLE 4 
__________________________________________________________________________ 
Microporous 
Membrane 
Composite 
Laminate Y 
Comparative 
Example 4 
Layer B 
Example 4 
Example 2 
__________________________________________________________________________ 
Weight, g/m.sup.2 
3.55 39.72 117.22 
113.3 
WVTR, g/m2/24 hrs 
88,605 18,992 13,528 
9,618 
Gurley No., secs 
2.7 impermeable 
-- -- 
Mullen Burst Press., psi 
58 157 180 182 
Machine Direction 
% Stretch, IP4 - 4 lb 
-- 6 52 6 
% Recovery -- 99 96 99 
% Stretch, IP4 - 12 lb 
-- 18 68 11 
% Recovery -- 98 96 99 
10% Stretch Force, lbs 
0.192 1.821 0.089 2.05 
25% Stretch Force, lbs 
0.712 3.228 0.210 3.99 
50% Stretch Force, lbs 
-- 3.031 1.14 4.04 
Maximum Load, lbs 
1.14 2.579* 18.29 15.8 
Elongation at Break, % 
53 237 291 388 
Transverse Direction 
% Stretch, IP4 - (4 lbs) 
-- 69 29 9 
% Recovery -- 95 98 99 
% Stretch, IP4 - (12 lbs) 
-- Break 76 27 
% Recovery -- -- 87 99 
10% Stretch Force, lbs 
0.036 0.241 0.32 0.81 
25% Stretch Force, lbs 
0.121 0.476 0.86 2.20 
50% Stretch Force, lbs 
0.257 0.703 1.167 4.20 
Maximum Load, lbs 
0.606 2.309 19.37 24.7 
Elongation at Break, % 
170 486 294 215 
__________________________________________________________________________ 
*Load at Break, lbs 
TABLE 5 
__________________________________________________________________________ 
Elastic 
Laminate X 
Fabric II 
Example 5 
Example 6 
Example 7 
__________________________________________________________________________ 
Weight, g/m.sup.2 
109.7 190.8 181.16 242.20 
WVTR, g/m2/24 hrs 
27,600 
13,157 7,869 6,792 
Mullen Burst Press., psi 
-- -- -- -- 
Machine Direction 
% Stretch, IP4 - 4 lb 
101 60 46 47 
% Recovery 95 97 98 98 
% Stretch, IP4 - 12 lb 
185 81 74 80 
% Recovery 94 96 96 96 
10% Stretch Force, lbs 
0.07 0.119 0.117 0.145 
25% Stretch Force, lbs 
0.18 0.255 0.314 0.351 
50% Stretch Force, lbs 
0.39 0.738 0.987 0.854 
Maximum Load, lbs 
24.1 33.0 31.85 34.89 
Elongation at Break, % 
371 348 374 367 
Transverse Direction 
% Stretch, IP4 - (4 lbs) 
32 25 17 14 
% Recovery 98 98 98 98 
% Stretch, IP4 - (12 lbs) 
66 85 55 42 
% Recovery 97 92 93 96 
10% Stretch Force, lbs 
0.15 0.343 0.484 0.576 
25% Stretch Force, lbs 
0.60 0.851 1.31 1.464 
50% Stretch Force, lbs 
1.42 1.68 2.682 3.113 
Maximum Load, lbs 
37.8 27.7 34.77 12.34 
Elongation at Break, % 
300 369 294 265 
__________________________________________________________________________ 
TABLE 6 
__________________________________________________________________________ 
Microporous 
Microporous 
Membrane, 
Membrane, 
Example 8, 
Composite 
Laminate V 
Example 8 
Stretched 
Layer C 
Example 8 
__________________________________________________________________________ 
Weight, g/m.sup.2 
12.6 14.5 48.4 142.7 
WVTR, g/m2/24 hrs 
71,739 67,139 19,245 13,749 
Gurley No., secs. 
7.6 14.2 impermeable 
-- 
Mullen Burst Press., psi 
115 118 172 178 
Machine Direction 
% Stretch, IP4 - 4 lb 
-- -- 5.5 59 
% Recovery -- -- 99 98 
% Stretch, IP4 - 12 lb 
-- -- 12 81 
% Recovery -- -- 97 93 
10% Stretch Force, lbs 
0.122 0.357 1.04 0.126 
25% Stretch Force, lbs 
0.522 1.258 1.77 0.286 
50% Stretch Force, lbs 
0.875 1.78 2.55 0.906 
Maximum Load, lbs 
1.929 2.643 3.37 32.59 
Elongation at Break, % 
161 102 2.09 277.8 
Transverse Direction 
% Stretch, IP4 - (4 lbs) 
-- -- 67 27 
% Recovery -- -- 95 98 
% Stretch, IP4 - (12 lbs) 
-- -- 141 62 
% Recovery -- -- 88 91 
10% Stretch Force, lbs 
0.17 0.05 0.10 0.256 
25% Stretch Force, lbs 
0.896 0.104 0.2 0.793 
50% Stretch Force, lbs 
1.806 0.243 0.35 1.853 
Maximum Load, lbs 
2.726 1.915 1.62 17.33 
Elongation at Break, % 
81 182 300 418 
__________________________________________________________________________ 
TABLE 7 
______________________________________ 
Elastic 
Example 9 
Fabric III 
Example 10 
______________________________________ 
Weight, g/m.sup.2 
191.4 248.0 363.3 
WVTR, g/m2/24 hrs 
7,875 16,247 5,584 
Mullen Burst Press., psi 
182 -- 218 
Machine Direction 
% Stretch, IP4 - 4 lb 
42 50 36 
% Recovery 97 96 99 
% Stretch, IP4 - 12 lb 
63 95 62 
% Recovery 95 95 97 
10% Stretch Force, lbs 
0.215 0.059 0.284 
25% Stretch Force, lbs 
0.470 0.177 0.594 
50% Stretch Force, lbs 
1.305 0.505 1.693 
Maximum Load, lbs 
41.9 47.94 34.56 
Elongation at Break, % 
301.4 258 218.5 
Transverse Direction 
% Stretch, IP4 - (4 lbs) 
16 136 20 
% Recovery 99 91 100 
% Stretch, IP4 - (12 lbs) 
39 175 51 
% Recovery 95 85 93 
10% Stretch Force, lbs 
0.654 0.043 0.662 
25% Stretch Force, lbs 
0.116 0.116 1.469 
50% Stretch Force, lbs 
3.304 0.276 2.602 
Maximum Load, lbs 
15.52 20.04 29.1 
Elongation at Break, % 
307 400 428 
______________________________________