U.S. patent application number 09/780626 was filed with the patent office on 2001-10-25 for fibrous polymeric material and its composites.
Invention is credited to Hannon, Gregory, Trapp, Benjamin.
Application Number | 20010033925 09/780626 |
Document ID | / |
Family ID | 23476592 |
Filed Date | 2001-10-25 |
United States Patent
Application |
20010033925 |
Kind Code |
A1 |
Trapp, Benjamin ; et
al. |
October 25, 2001 |
Fibrous polymeric material and its composites
Abstract
A three dimensional porous elastomeric polymeric material is
described that has a morphology primarily of polymeric fibers fused
randomly along portions of their length, with a cross-section of a
network of irregular polymeric areas that are interconnected to
define interconnected voids; where the bulk density of the material
is at least 0.35 grams/cc. The material is useful in garment and
other protective covering applications where it can be adhered to
various substrates to provide improved abrasion resistance.
Composites of the material are described also.
Inventors: |
Trapp, Benjamin; (Newark,
DE) ; Hannon, Gregory; (Newwark, DE) |
Correspondence
Address: |
W. L. Gore & Associates, Inc.
551 Paper Mill Road
P.O. Box 9206
Newark
DE
19714-9206
US
|
Family ID: |
23476592 |
Appl. No.: |
09/780626 |
Filed: |
February 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09780626 |
Feb 9, 2001 |
|
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|
09374387 |
Aug 13, 1999 |
|
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Current U.S.
Class: |
428/311.51 ;
428/329; 442/328 |
Current CPC
Class: |
B32B 2305/026 20130101;
D06N 2209/105 20130101; D04H 1/4358 20130101; B32B 2437/02
20130101; B32B 2307/724 20130101; D04H 1/56 20130101; A43B 1/14
20130101; D06N 2209/128 20130101; D04H 1/435 20130101; B32B
2307/718 20130101; B32B 2262/0292 20130101; D04H 1/4334 20130101;
D06N 3/106 20130101; Y10T 442/601 20150401; D01F 6/70 20130101;
B32B 2307/554 20130101; D04H 1/4291 20130101; D06N 2209/123
20130101; A41D 31/102 20190201; A43B 23/07 20130101; B32B 5/02
20130101; B32B 2437/00 20130101; Y10T 428/249964 20150401; B32B
3/26 20130101; Y10T 428/257 20150115; A43B 7/125 20130101 |
Class at
Publication: |
428/311.51 ;
442/328; 428/329 |
International
Class: |
D21H 011/00 |
Claims
1. A three dimensional porous material comprised of: polymeric
fibers fused together randomly along portions of their length such
that the cross-section comprises a network of irregular shapes of
polymer that are interconnected so as to define void space; said
material having a bulk density of at least 0.35 gm/cc, being
elastomeric, and having an air permeability of at least 10
cm.sup.3/cm.sup.2/sec.
2. A three dimensional porous material comprised of: polymeric
fibers fused together randomly along portions of their length such
that the cross-section comprises a network of irregular shapes of
polymer that are interconnected so as to define void space; said
material having a bulk density of at least 0.35 gm/cc, being
elastomeric; having an air permeability of at least 10
cm.sup.3/cm.sup.2/sec; having a basis weight between 30 and 300
g/m.sup.2; and having an abrasion resistance of at least 100
cycles.
3. The material of claim 2 wherein the abrasion resistance is at
least 1000 cycles.
4. The material of claim 2 wherein the basis weight is between 30
and 80 g/m.sup.2 and the abrasion resistance is at least 100
cycles.
5. The material of claim 2 wherein the basis weight is between 80
and 100 g/m.sup.2 and the abrasion resistance is at least 150
cycles.
6. The material of claim 2 wherein the basis weight is between 100
and 150 g/m.sup.2 and the abrasion resistance is at least 300
cycles.
7. The material of claim 2 wherein the basis weight is between 80
and 120 g/m.sup.2 and the abrasion resistance is at least 750
cycles.
8. The material of claim 2 wherein the basis weight is between 150
and 300 g/m.sup.2 and the abrasion resistance is at least 1000
cycles.
9. The material of claim 1 wherein the polymeric fibers are
comprised of polyurethanes, polyetheresters, polyetheramides or
polyolefins.
10. The material of claim 2 wherein the polymeric fibers are
polyurethane.
11. The material of claim 2 in which the polymeric fibers contain
an additive.
12. The material of claim 11, wherein said additive comprises a UV
stabilizer.
13. The material of claim 1, wherein the polymeric fibers comprise
a thermoplastic polyurethane comprising diphenylmethane
diisocyanate, polycaprolactone diol and butane diol.
14. The material of claim 2, wherein the polymeric fibers comprise
a thermoplastic polyurethane comprising diphenylmethane
diisocyanate, polycaprolactone diol and butane diol.
15. The material of claim 1, wherein said polymeric fibers comprise
a thermoplastic polyurethane of dicyclohexylmethane diisocyanate,
polycaprolactone diol and butane diol.
16. The material of claim 2, wherein said polymeric fibers comprise
a thermoplastic polyurethane of dicyclohexylmethane diisocyanate,
polycaprolactone diol and butane diol.
17. A process of making the three-dimensional porous polymeric
material of claim 1 or 2 comprising melt blowing an elastomeric
polymer onto a carrier surface having an air permeability of less
than 100 cm.sup.3/cm.sup.3/sec, and removing the carrier
surface.
18. A garment comprising the material of claim 1 or claim 2 wherein
the garment comprises seams formed by joining a first region of
polymeric fibers of the porous material to a second region of
polymeric fibers.
19. A garment comprising the material of claim 1 or 2 laminated to
at least one second material comprising a water resistant, water
vapor permeable component, wherein the garment comprises water
resistant seams formed by joining polymeric fibers of the porous
material to said at least one second material.
Description
[0001] This application is a continuation-in part of U.S. patent
application Ser. No. 09/374,387, filed Aug. 13, 1999.
FIELD OF THE INVENTION
[0002] The present invention relates to a porous, fibrous
elastomeric polymeric material for durable end uses such as in
garments, footwear, clothing accessories, other protective
coverings, and the like. This polymeric material has a unique
combination of durability properties such as abrasion and pilling
resistance with an acceptable handle and air permeability. This
invention also relates to water resistant, water-vapor permeable
composites of the polymeric material.
BACKGROUND OF THE INVENTION
[0003] A large variety of durable end uses require use of flexible
polymeric materials with high abrasion resistance. If porosity or
air permeability is not a requirement of these flexible materials
in specific end uses, non-porous polymer sheets and films are
typically used as the material of choice. Typical examples of such
end uses are raincoats, inflatable rafts, conveyor belt linings
etc. made from wear resistant polymers such as polyethylene, nylon,
polyurethane etc. If, in addition, the end use requires
conformability then such non-porous sheets and films are made from
wear resistant, but elastic polymers such as polyurethanes,
polyetheresters and the like. Such films and sheets of these
polymers are typically made by common polymer processing techniques
such as cast extrusion or film blowing. As shown schematically in
FIG. 1a, when viewed in cross-section, such polymeric films and
sheets show the non-porous nature of such materials.
[0004] Porosity and air permeability are desired features in a
flexible material for a number of durable end uses such as clothing
and accessories, filtration etc. In these cases, the material
should provide open passages from one side to the other to allow
passage of air and vapors through it. Woven and knitted fabrics are
examples of polymeric, air permeable materials with acceptable
durability such as abrasion resistance as they are based on
continuous lengths of highly oriented fibers that are first formed
from the polymer, optionally towed into yarns and then woven or
knitted together in subsequent steps. For example, in construction
of re-usable garments and clothing accessories, woven and knitted
fabrics are used as they maintain the aesthetic and functional
properties of the article even after continued use over a prolonged
time period. This is so because woven and knitted fabrics,
typically obtained from inelastic polymers such as nylon,
polyester, polypropylene, are acceptably resistant to effects such
as abrasion, laundering, weathering etc. As shown schematically in
FIG. 1b, when viewed in cross-section, such fabrics show a distinct
assemblage of fibers organized in a regular weaving or knitting
pattern. Expectedly, in these fabrics, no fusion of fibers take
place and the fibers maintain their individual identity.
Elastomeric properties can be imparted to such fabrics by
incorporating some elastic fibers along with the hard or inelastic
fibers. 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.
[0005] Non-woven fabrics also are typical of flexible, porous
materials exhibiting porosity and air permeability. However, these
materials are used almost exclusively for non-durable end uses such
as garments meant for single use or very limited re-use primarily
because of their poor resistance to abrasive forces. Usually, under
such forces the non-woven fabrics rapidly disintegrate, leading to
loss of aesthetic and/or functional properties. Resistance to
abrasion is one of the key requirements of a material to be
suitable for durable end uses like garment and clothing
accessories. Unlike knitted and woven fabrics, non-woven fabrics
exhibit very poor abrasion resistance. Typically, when subjected to
abrasive forces, a non-woven fabric will abrade rapidly resulting
in defects such as pilling or roping which are aesthetically
unappealing. The poor abrasion resistance of non-woven fabrics
result from its structural characteristics. As shown schematically
in FIG. 1c, when viewed in cross-section, non-woven fabrics show a
random assemblage of natural or synthetic fibers lightly bonded
together. Within this structure, abrasion resistance can be
improved by increasing the degree of bond or entanglement between
the fibers, but that comes at the expense of other desirable
properties such as hand and air permeability. To date, at
comparable basis weights, we are not aware of the availability of
any non-woven fabric that is comparable to woven and knitted
fabrics in terms abrasion resistance and hand. As a result,
non-woven fabrics are generally not looked upon as a viable
material for durable end uses that require air permeability.
Non-woven fabrics also can be made to exhibit elastomeric
properties by choosing appropriate polymers. For example, U.S. Pat.
Nos. 3,439,085; 5,230,701; 4,660,228 describe elastomeric
non-wovens made from polyurethane polymers. Similarly, U.S. Pat.
Nos. 4,724,184 and 4,707,398 teach respectively how elastomeric
non-wovens can be obtained from copolyetheramides and from
copolyetheresters.
[0006] Many applications which require the wear durability
described previously are also subjected to significant levels of UV
radiation and weathering. As nonwovens are extended into these more
harsh applications, resisting degradation due to UV radiation or
weathering will be advantageous. A polymer chemistry will be
required which resists this degradation, but does not negatively
impact the processability or final properties of the fabric.
[0007] Non-woven fabrics are manufactured by two broad categories
of processes. In the first category, referred to as fiber to web
processes, staple or short fibers are converted into webs using
processes such as air laying, carding, hydro-entangling etc. In the
other category, referred to as polymer laid processes, bulk polymer
is fiberized using an extrusion process and directly collected in
form of a web. Melt blowing and spun bonding are typical examples
of polymer laid processes. These manufacturing processes for
non-woven fabrics are relatively less expensive than producing
woven or knitted fabrics as the conventional steps of towing and
weaving or knitting of fibers or yarns are eliminated.
Consequently, there continues to be considerable incentive in
developing non-woven fabric-like materials that can provide
improved abrasion resistance or end-use durability without
significantly affecting other fabric properties such hand, air
permeability etc.
[0008] It is therefore apparent that there continues to be a need
for a porous polymeric material that combines the cost advantage of
the non-woven processing and the abrasion resistance of the
non-porous film to match that of woven and knitted fabrics. In
addition, resistance of such materials to UV radiation would
provide significant benefits in harsh applications where the
material is subject to UV radiation and weathering. Use of such
abrasion resistant polymeric material would be widespread not only
in extending the conventional use of non-wovens but also more
remarkably in areas where woven and knitted fabrics are currently
used including creation of water resistant, water vapor permeable
composites described in U.S. Pat. Nos. 4,194,041; 5,026,591;
4,532,316 and 5,529,830 to W. L. Gore and Associates for durable
end uses such as garments and clothing accessories for highly
demanding outerwear applications.
SUMMARY OF THE INVENTION
[0009] It is a purpose of the present invention to provide a porous
polymeric material that exhibit properties in between that offered
by a non-porous film and that offered by fibrous non-woven fabric.
For example, the material of the invention demonstrates durability
properties such as abrasion resistance at a level significantly
greater than conventional non-woven fabrics such that it can
perform at least comparably to certain woven and knitted fabrics
while maintaining comparable air permeability. In addition to the
enhanced durability of the material, resistance to UV radiation is
possible.
[0010] The purpose is accomplished herein by creating a three
dimensional porous material comprised of polymeric fibers fused
together randomly along portions of their length such that the
cross-section comprises a network of irregular shapes of polymer
that are interconnected so as to define void space, said material
having a bulk density of at least 0.35 g/cc. The material is
elastomeric and has a moisture vapor transmission rate of at least
1000 g/m.sup.2/day.
[0011] In another aspect, the material is defined as a three
dimensional porous material comprised of
[0012] polymeric fibers fused together randomly along portions of
their length such that the cross-section comprises a network of
irregular shapes of polymer that are interconnected so as to define
void space; said material
[0013] having a bulk density of at least 0.35 g/cc;
[0014] being elastomeric;
[0015] having a moisture vapor transmission rate of at least 1000
g/m.sup.2/day;
[0016] having a basis weight between 30 and 300 g/m.sup.2; and
[0017] having an abrasion resistance of at least 100 cycles.
[0018] The polymeric materials of this invention have a novel
structure that imparts to it durability properties that are far
superior to conventional non-woven fabrics. The structure of this
invention also provides for little resistance to the through
passage of air, which is important to applications requiring this
combination of properties. These properties makes the polymeric
material of this invention a viable alternative to conventional
woven and knitted fabrics in many applications. This aspect of the
invention can be defined as
[0019] a three dimensional porous material comprising polymeric
fibers fused together randomly along portions of their length such
that the cross-section comprises a network of irregular shapes of
polymer that are interconnected so as to define void space; said
material
[0020] having a bulk density of at least 0.35 g/cc;
[0021] being elastomeric;
[0022] having an air permeability of at least 10
cm.sup.3/cm.sup.2/sec;
[0023] having a basis weight between 30 and 300 g/m.sup.2; and
[0024] having an abrasion resistance of at least 100 cycles.
[0025] Many end uses which require a combination of wear durability
and permeability, as described previously, are also subjected to
significant levels of UV radiation and weathering. It would thus be
advantageous for the material to have a polymer chemistry which
resists this degradation, but does not negatively impact the
processability or final properties of the material.
[0026] It is also a purpose of the present invention to use this
material to create novel water resistant, water vapor permeable
composites or laminates with improved durability properties such as
abrasion resistance without compromising other functional
attributes such as water vapor permeability, water resistance and
handle that are retained over the intended life of articles such
garments and clothing accessories made from these composites.
DEFINITIONS
[0027] As used in this application:
[0028] "Porous" with respect to films and membranes means full of
passages or channels from one side to another.
[0029] "Non-porous" with respect to films and membranes means
having no passages or channels.
[0030] "Flexible" means bendable without breaking.
[0031] "Water resistant" means the material in question passes the
water resistance test described further below.
[0032] "Water vapor permeable" means that the material in question
has a moisture vapor transmission rate (MVTR) of at least 1000
grams/m2/day.
[0033] "Durable" or "durability" means that the material in
question is abrasion resistant.
[0034] "Garment" means any article that can be worn, and includes
footwear, hats, gloves, shirts, coats, trousers, etc.
[0035] "Fibrous" means fiber-like structures.
[0036] "Elastomeric" means a material capable of stretching at
least 50% of its original length when a force is applied and upon
release of the stretching force will return to at least 80% of its
original length.
[0037] "Air Permeable" means that the material has an air
permeability, as determined by the test described herein, of at
least 10 cm.sup.3/cm.sup.2/sec.
[0038] "Irregular" means not of any regular geometrical shape.
[0039] "Ribbon" means a narrow three dimensional strip.
[0040] "Microporous" means a structure not visible to the naked
eye.
[0041] "Coalesced" means merged to the point that individual
identity is lost.
[0042] "Fabric" means a material made from textile fibers or
yarns.
[0043] "Non-woven fabric" means a porous, textile-like substance
composed primarily or entirely of fibers randomly assembled in a
web without use of a weaving or knitting process.
[0044] Percentage stretch and recovery are defined as
%stretch=(L.sub.s/L.sub.o-1).times.100
%recovery=([L.sub.s-L.sub.f]/[L.sub.s-L.sub.o]).times.100
[0045] where L.sub.o is the original length, L.sub.s the length
when a stretching force is applied, and L.sub.f is the length when
the stretching force is released.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1A is a schematic view of the cross-section of a
non-porous polymeric film of the prior art.
[0047] FIG. 1B is a schematic view of the cross-section of a woven
fabric of the prior art.
[0048] FIG. 1C is a schematic view of the cross-section of a
non-woven fabric of the prior art.
[0049] FIG. 2A is a photomicrograph of the cross-section of a
commercial elastomeric non-woven fabric of comparative example 3 at
a magnification of 200.times..
[0050] FIG. 2B is a photomicrograph of the cross-section of a
commercial elastomeric non-woven fabric of comparative example 7 at
a magnification of 400.times..
[0051] FIG. 3A is a schematic view of the surface of the polymeric
material of this invention.
[0052] FIG. 3B is a schematic view of a cross-section of the
polymeric material of this invention.
[0053] FIG. 4A is a photomicrograph of the surface of the polymeric
material of this invention as described in Example 1 at a
magnification of 100.times.. Basis Weight: about 130 g/m.sup.2.
[0054] FIG. 4B is a photomicrograph of the cross-section of the
polymeric material of this invention as described in Example 1 at a
magnification of 200.times.. Basis Weight: about 130 g/m.sup.2.
[0055] FIG. 5A is a photomicrograph of the surface of the polymeric
material of this invention as described in Example 2 at a
magnification of 100.times.. Basis Weight: about 130 g/m2.
[0056] FIG. 5B is a photomicrograph of the cross-section of the
polymeric material of this invention as described in Example 2 at a
magnification of 450.times.. Basis Weight: about 130 g/m.sup.2.
[0057] FIG. 6 is a photomicrograph of the cross-section of the
polymeric material of this invention at a magnification of
500.times.. Basis Weight: about 80 g/m.sup.2.
[0058] FIG. 7 is a photomicrograph of the cross-section of the
polymeric material of this invention at a magnification of
600.times.. Basis Weight: about 40 g/m.sup.2.
[0059] FIG. 8 illustrates the abrasion resistance of the polymeric
material of this invention and of commercial elastomeric non-woven
fabrics as a function of bulk density. Solid Line shows the trend
for materials of this invention. Broken Line shows the trend for
commercially available elastomeric non-woven fabrics.
[0060] FIG. 9 is a schematic representation of the preferred method
of obtaining the polymeric material of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0061] As stated earlier, non-porous films made of abrasion
resistant elastomeric polymeric materials are known to be flexible
as well as abrasion resistant which makes them suitable for durable
end uses. They, however, are not suitable for durable end uses that
require air permeability, since such films, as shown schematically
in FIG. 1a, are not porous in nature and are void free, shown as
10, and thus prohibit the passage of air. In such cases, synthetic
woven or knitted fabrics are used as they provide the needed
flexibility, porosity and abrasion resistance required. The
resulting structure, as shown schematically in FIG. 1b for woven
fabric, therefore is made up of individual fibers 20, grouped in
yarns 21, and assembled in a regular arrangement. The porosity is
derived from the spacing between the fibers and the abrasion
resistance is provided by the highly oriented strong fibers itself.
Woven and knitted fabrics, both elastomeric as well as
non-elastomeric, are rather expensive due to a large number of
processing steps involved in converting a polymer into the fabric.
Considering the widespread use of these fabrics in durable end
uses, it is desirable to have a material that can perform like
woven and knitted fabrics but is structurally different to permit
lower cost processing.
[0062] Non-woven fabrics that are made by polymer laid processes
offer such processing advantages as the capability of a synthetic
polymer to be directly fiberized and converted into a fabric
without any need for weaving or knitting. Structurally, as shown
schematically in FIG. 1c, such non-woven fabrics are made of
randomly arranged fibers 22 where the fibers are thermally,
chemically or mechanically lightly bonded to one another at 23.
FIGS. 2a and 2b show the cross-sectional photo/micrograph of two
different commercially available elastomeric non-woven fabrics made
from polyurethane polymers. The structure consists essentially of
randomly arranged individual polyurethane fibers that are lightly
bonded to other fibers in some cases. This non-woven structure
offers porosity between the fibers, but the abrasion resistance is
usually very poor. As a result, these elastomeric non-woven fabrics
are not suitable for durable end uses. When subjected to abrasion,
the lightly bonded fibers are easily debonded and rapidly results
in breakage, pilling or roping upon further abrasion. Considering
its processing advantages, it would be desirable if non-woven
fabrics could be made as abrasion resistant as woven and knitted
fabrics without compromising other functional characteristics such
as porosity and handle. To achieve that, a different fibrous
structure is required to provide such improved resistance. The
present invention accomplishes that.
[0063] The present invention describes a three-dimensional, porous
elastomeric polymeric material, usually in the form of a sheet or
film, that possess a structure which combines the structural
features of a non-porous film and a non-woven fabric. Typically the
material of this invention ranges in thickness from 3 to 50 mils,
preferably 5 to 25 mils. The basis weight of the material can also
vary from 30 to 300 grams/m.sup.2, preferably 40-200 and most
preferably 80 to 150 grams/m.sup.2.
[0064] FIGS. 3a and 3b schematically illustrate the structure of
the material of this invention, and FIGS. 4 to 7 are
photomicrographs of the same. The surface of the material invented
is fibrous in nature as shown schematically in FIG. 3a and through
photomicrographs in FIGS. 4a and 5a. In FIG. 3a, the surface 1
consists predominantly of randomly arranged polymeric strands 2
formed by individual fibers randomly fused to one another at least
along part of its length such as to lose their individual identity.
In addition, the strands 2 are also coalesced at junctions 3 where
the strands have contacted each other. The strands vary in size
from 10 to 100 microns. Few individual fibers 4 are also seen to be
present. A different perspective of the structural features of the
material of this invention can be observed from its cross-sectional
view as shown schematically in FIG. 3b. In terms of definition, a
cross-section represents a section of the material taken along a
plane which is perpendicular to the material's surface. The
cross-section of this material (see FIGS. 3b, 4b & 5b),
consists primarily of irregularly shaped non-porous polymeric areas
6 along with that of few fibers 4, still existing in their
individual form. The polymeric areas 6 represent the cross-section
of the polymeric strands 2. The diameter of the individual fibers
vary from 5 to 30 microns and the cross-sectional area occupied by
the irregularly shaped areas are greater than 50% of the total
cross-sectional area occupied by the polymer structure. This ratio
of area to the total polymer area depends on the basis weight of
the material. As seen in FIGS. 5, 6 and 7, higher basis weight
material show more coalescence, thereby resulting in the ratio of
strand area to polymer area to be higher. The porosity of the
structure arises from the network of interconnected voids 7 that
provide passages for air permeability.
[0065] Thus, in terms of photomicrographs, the polymeric material
appears to have a structure that is comprised of a surface
primarily containing polymeric strands fused at least at crossover
points, and an inner cross section of predominantly polymeric
strands fused partially at least along abutting areas, and forming
a non-porous network of irregularly shaped areas of polymer that
are interconnected so as to define interconnected voids.
[0066] The polymeric material of this invention, due to the novel
structure described above, exhibits properties that lie between
that of a non-porous film and that of a non-woven fabric. For
example, the bulk density of the material of this invention is
higher than that of common elastomeric non-wovens but less than
that of a non-porous film. For example, as listed in Table 2, the
bulk density of commonly available elastomeric non-wovens varies
from 0.20 to 0.36 grams/cm3, whereas the density of the elastomeric
polymers used to make these ranges from 0.9 to 1.25 grams/cm3. In
comparison, the bulk density of the material of this invention is
at least 0.35 grams/cm3 and most commonly in the range of 0.40 to
0.55 grams/cm3. The increased density is a natural consequence of
the novel structure with reduced porosity caused by the presence of
the coalesced, dense polymeric areas that are non-porous in nature.
The density can be higher so long as the MVTR is above the
preferred 1000 g/m.sup.2/day value. In another aspect of the
invention the density can be higher so long as the air permeability
is greater than the preferred 10 cm.sup.3/cm.sup.2/sec value.
[0067] The porous polymeric material of this invention is
elastomeric in nature. These properties are controlled by the
amount of coalesced ribbons within the structure as well as the
overall basis weight. Generally speaking, higher coalescence and
higher basis weights produce stronger material with increased force
required to stretch the material. Typically, irrespective of its
orientation, the material can be stretched at least 50%, preferably
at least 100% and most preferably at least 300% upon application of
a tensile load. Upon removal of the load, the material recovers at
least 80% of its original dimension, preferably recovers at least
90% in both the machine and the transverse directions.
[0068] The unique structure of the porous polymeric material of
this invention has a remarkable effect on durability properties
such as abrasion resistance. When the surface of the invented
material is abraded, the polymeric strand structure being one-step
closer to that of a non-porous film impart added resistance to
abrasion forces. FIG. 8 compares the abrasion resistance of the
invented material and commercially available elastomeric non-woven
fabrics at different basis weights. Clearly, the abrasion
resistance of the material of this invention is at least 2 times,
more commonly 4 times higher than that offered by elastomeric
non-woven fabrics of comparable basis weight but of much lower bulk
densities. For a given polymer, abrasion resistance increases with
basis weight particularly at higher basis weights. In general the
abrasion resistance will be greater than 50 cycles. For basis
weights greater than 70 gram/cm.sup.2, the abrasion resistance is
preferably at least 150 cycles and most commonly at least 300
cycles. At the minimum, the high abrasion resistance of the
invented material makes it comparable in performance to certain
woven and knitted fabrics. Typically, the abrasion resistance of
the invented material is significantly greater than that for woven,
knitted or non-woven fabrics of comparable basis weights. For
example, a 136 gram/m.sup.2 woven Nylon Cordura.RTM. fabric has an
abrasion resistance of 430-650 cycles as compared to a 130
gram/m.sup.2 of this invention commonly having an abrasion
resistance that is three-fold higher.
[0069] In general, when the basis weight is between 30 and 80
g/m.sup.2, the abrasion resistance should be at least 100 cycles.
When basis weight is between 80 and 100 g/m.sup.2, the abrasion
resistance should be at least 150 cycles. When it is between 100
and 150 g/m.sup.2, the abrasion resistance should be at least 300
cycles. When basis weight is between 80 and 120 g/m.sup.2, the
abrasion resistance is preferably at least 750 cycles. When basis
weight is between 150 and 300 g/m2, the abrasion resistance should
be at least 1000 cycles.
[0070] The material of this invention can be formed using
conventional polymer laid processes such as meltblowing and
spunbonding with some process adjustments or subsequent operations
such as densification by calendering, if necessary. The invented
material, however, is preferably formed by a melt blowing process
such as that described in Wente, Van A., "Superfine Thermoplastic
Fibers", in Industrial Engineering Chemistry, vol.48, pages 1342
(1965) except that a drilled die is preferably used. Referring to
FIG. 9, the thermoplastic polymer is fed into an extruder 8 which
feeds a melt blowing die 9. As the polymer is extruded, a high
velocity stream of heated air draws and attenuates the extrudate
into a stream of fine fibers 10 which is then collected on a
carrier substrate 11 moving over a perforated cylindrical collector
12 to create the layered composite 14 with the invented material 13
on top of the carrier substrate 11. The collector can alternatively
be a perforated belt. Usually vacuum is applied at the collector to
aid in formation of a fibrous web. Alternatively, the use of the
carrier substrate can be eliminated if the collector surface has
the correct release properties to prevent sticking of the fibers
and also provides the appropriate level of air permeability.
[0071] In the above method, the melt blown fibers are collected in
a random fashion on the substrate prior to complete solidification
so that the fibers are able to coalesce to one another and form the
material of this invention. The carrier substrate is preferably
air-permeable such as woven, knitted or non-woven fabrics or metal
or plastic screen and meshes to aid and regulate the air flow
through the collector which can significantly affect the
coalescence within the structure formed. Preferably, the carrier
fabric is a woven fabric with an air permeability of less than 100
cm.sup.3/cm.sup.2/sec. At higher substrate permeability, under
identical process conditions, the material formed will typically
have lower bulk density and lower abrasion resistance. However, the
effect of increased air permeability of the carrier substrate or
the collector can be somewhat compensated by adjusting the process
conditions such as higher melt temperature, higher throughput, and
shorter distance of the collector from the die to name a few.
[0072] The surfaces of the material of the invention can be
patterned or embossed. If the carrier substrate or the collector
possesses a pattern, such as the weave pattern in case of a woven
fabric or metal screen, a mirror image of the pattern can be
transferred onto one surface of the material of this invention. The
clarity of the pattern will be dependent on the specific details of
the melt blowing conditions employed. Alternatively, such a pattern
can be created on one or both the surfaces of the invented material
by using conventional secondary operations such as embossing.
[0073] Elastomeric synthetic polymers are used to create the porous
polymeric material of this invention. Typically, such polymers need
to be thermoplastic in nature with low modulus of elasticity, low
hardness, high degree of elongation and high resistance to abrasion
and wear. Commonly, such elastomeric polymers are block copolymers,
preferably belonging to polyurethanes, polyetherester or
polyetheramide family. Such thermoplastic elastomeric copolymers
are available commercially from a number of sources such as
Morthane.RTM. and Estane.RTM. brand of polyurethanes from Morton
Polyurethanes (Chicago, Ill.) and B. F. Goodrich (Brecksville,
Ohio), respectively. Similarly, polyetheresters are available as
Hytrel.RTM. from Dupont (Wilmington, Del.); as Arnitel.RTM. from
DSM (Evansville, Ind.); as Riteflex.RTM. from Ticona, (Summit,
N.J.) and polyetheramides as Pebax.RTM. from Elf Atochem America,
Pa.
[0074] The choice of the specific family of elastomeric polymer is
dictated by the intended end use as well as the processability
considerations. Hardness of the polymer dictates the stiffness,
drape and the hand of the material. Typically, the hardness of the
polymer should be as low as possible without compromising its
abrasion resistance. The hardness can range from 60 Shore A to 60
Shore D, preferably from 60A to 40D. In addition to being soft,
high elongation to break is also a characteristic of these
elastomeric polymers. Typically, the elongation to break should be
at least 300%, preferably at least 400%, most preferably greater
than 500%. In addition to mechanical properties, other requirements
such as temperature resistance, UV stability, solvent resistance
etc. will also dictate the specific polymer or additive(s) to be
used. In cases where a minimal amount of challenge from UV
radiation or weathering will be encountered, stabilizer packages
can be utilized. These stabilizer packages act by a variety of
methods to control the degradation and the effects of degradation.
These packages can include energy absorbing elements to protect the
polymer or oxidation scavengers to minimize the effect of
degradation. Instances may arise where protection from severe or
long term environmental exposure is needed. In these instances, the
polymer backbone should be chosen from an inherently stable
chemistry. Typically, in urethane chemistry, aromatic hard segments
should be replaced with aliphatic hard segments or similarly stable
chemistries. These polymers can be further protected with the
addition of stabilizers. These changes in chemistry must still
allow for the production of the invention to be viable
candidates.
[0075] To be processable, the polymer should be thermally stable
and it should also possess specific melt viscosity characteristics
under the desired processing conditions. Generally, a melt
viscosity less than 1000 poise is required to obtain acceptable
melt blowing properties and the processing temperatures should be
adjusted accordingly for the specific elastomeric polymer being
used. In terms of melt flow index (MFI) measured at 195.degree. C.,
5 kg. load according to ASTM D1238-89, the polymer should exhibit
an MFI greater than 10 g/10 minutes, preferably greater than 25
g./10 minutes and most preferably greater than 50 g./10
minutes.
[0076] The polymers used may be mixed with other appropriate
additives such as, for example, pigments, colorants, antioxidants,
stabilizers, flow promoters, slip agents, fillers, solid solvents,
cross-linking agents, particulates and other processing additives.
In addition, the polymers may also contain additives to impart
water repellency, oil repellency, hydrophilicity, soil removal and
other such characteristics. One example of such additives is the
use of fluorinated compounds to impart water and oil repellency to
melt blown fibers as described in U.S. Pat. No. 5,025,052. Another
example is the use of cross-linking agents, like multi-functional
isocyanates to improve the heat and chemical resistance of
thermoplastic polyurethane polymers.
[0077] Thermoplastic polyurethanes, due to their high abrasion
resistance, low hardness and excellent elastomeric properties, are
the most preferred polymer to create the material of this
invention. Provided they have the desired melt rheological
properties for processing, such polyurethanes can be based on
either polyester or polyether soft segments and can have aromatic
or aliphatic isocyanate moieties forming the hard segment. Typical
properties of such thermoplastic polyurethanes range from 70A to
60D for hardness, 400 to 1000% break elongation and 1.05 to 1.20
for specific gravity. In terms of processability, such
polyurethanes should be processable (melt viscosity less than 1000
poise) at temperatures without significant thermal degradation.
[0078] Water resistant, water vapor permeable substrates with
acceptable softness and flexibility are generally manufactured
through direct coating or adhesive lamination with durable fabric
layers to create durable composites that are water resistant, but
water vapor permeable. As described in U.S. Pat. Nos. 4,194,041;
5,036,551 and 5,529,830, such composites are used commonly for
garment applications, as they provide improved comfort by allowing
the passage of moisture from perspiration while offering protection
from rain and wind. The durable polymeric materials of this
invention are combined with a such water resistant, water vapor
permeable substrate to create durable composites of this
invention.
[0079] A large variety of water resistant, water vapor permeable
substrates can be used to create such durable composites.
Non-porous films of hydrophilic copolymers, such as
polyetherurethanes, polyetheresters and polyetheramides are typical
examples of such substrates and have been described respectively in
U.S. Pat. Nos. 4,194,041; 4,725,481; 4,230,838 for example. In
practice, these polymers are converted into thin films by
extrusion, film blowing or solvent casting. The films are then
subsequently adhered to the invented material at least on one side
to create the water resistant, water vapor permeable composites.
Alternatively, such hydrophilic polymers can be extruded or solvent
coated directly onto the invented material to create the composites
of this invention. In such instances, the hydrophilic polymer can
exist as a layer on the surface with minimal penetration of the
porous material or it can be fully penetrated where it occupies the
entire porous structure. Typically, however, the hydrophilic
polymer will only be partially penetrated into the porous structure
of the invented material to create enough pore occlusion to impart
acceptable water resistant properties without compromising the
water vapor permeability.
[0080] Microporous polymer membranes are also used as water
resistant, water vapor permeable substrates. The preferred
microporous polymer membrane is expanded polytetrafluoroethylene
(ePTFE) which is characterized by a multiplicity of open,
interconnecting microscopic voids, high void volume, high strength,
softness, flexibility, and stable chemical properties. U.S. Pat.
Nos. 3,953,566 and 4,187,390 describe the preparation of such
microporous ePTFE membranes and are incorporated herein by
reference. While retaining permeability, ePTFE membranes can be
further treated to impart improved resistance to contamination by
low surface tension liquids such as solvents and oils. Typically,
such oleophobic ePTFE is obtained by treating it with
fluoropolymers as described in U.S. Pat. No. 5,375,441.
[0081] For improved protection from wind and from contamination,
composites of microporous membranes with hydrophilic polymers are
also used as substrates. The continuous hydrophilic polymer layer
selectively transports water vapor by diffusion, but does not
support pressure driven liquid or air flow. Therefore, moisture,
i.e., water vapor, is transported but the continuous layer
precludes the passage of such things as air-borne particles,
micro-organisms, oils or other contaminants. The continuous layer
also makes the composite to be air impermeable. A preferred
composite substrate is ePTFE with a coating of a continuous layer
of a hydrophilic polymer such as polyurethane as described in U.S.
Pat. No. 4,194,041. If needed, oleophobic ePTFE can also be used to
create a composite substrate as described above.
[0082] Novel water resistant, water vapor permeable composites can
be further created by combining the water resistant, water vapor
permeable composites with the porous elastomeric material of this
invention at least on one side of the substrate. If desired,
another layer of the invented material or a layer of conventional
woven, knitted or non-woven fabric can be bonded to the other side
of the substrate. The preferred method of combination is through
adhesive lamination. For example, as described in U.S. Pat. No.
4,532,316, a polyurethane adhesive can be used in a discontinuous
pattern to create the desired composites. Alternatively, as
described in U.S. Pat. No. 5,036,551, a continuous layer of
hydrophilic polyurethane can be used as the adhesive to create the
desired composites. Care must be taken to ensure that the
temperatures encountered during the lamination step are not high
enough to distort the surface of the polymeric material invented
here.
[0083] The composite made using the porous elastomeric polymeric
material of this invention is novel as it affords the durability
properties at least comparable to composites made from conventional
woven or knitted fabrics. Additionally, because of the elastomeric
nature of the material, the resulting composite is soft and of
acceptable hand. If the substrates used are also elastomeric in
nature, the composites formed can exhibit elastic properties such
as high stretch and recovery that are desirable for garments and
accessories requiring form fitting characteristics. These novel
composites are water vapor permeable to the level of at least 1000
g/m.sup.2/day.
[0084] The novel materials of the invention can be converted into
garments or other protective coverings by a variety of means. One
of the ways these constructions can be assembled is to create seams
by joining the fibrous material surface to itself or to another
fabric surface.
[0085] The novel composites can be converted into water resistant,
water vapor permeable garments and clothing accessories by a
variety of means. One of the ways these composites can be assembled
into such articles is to create water resistant seams by joining
the fibrous material surface of the composite to itself or to
another fabric surface of a composite. Other uses of the composites
include bivy bags, tenting and other protective coverings.
TEST PROCEDURES
[0086] A variety of different tests have been used in the following
examples to demonstrate the various properties of the porous
polymeric materials of this invention and of the composites made
from it.
[0087] In view of the difficulty in separating composites into
their individual components, it is understood that when one
component is said to have a certain property, such as a certain
moisture vapor transmission rate, that property can be measured by
testing the entire composite; for if the composite meets the test,
the individual components inherently must meet the test.
[0088] Basis Weight
[0089] Basis weight was measured by cutting a 4.25 inch diameter
(0.009 m.sup.2) specimen. Average weight of 3 specimens is recorded
and reported in grams/m.sup.2. In cases where the sample on a
substrate, the weight of both was recorded and the weight of the
substrate is subtracted off later.
[0090] Thickness
[0091] Thickness was measured according to ASTM-D-1977-64 using a C
& R Thickness Tester, model no. CS55 with a 2 oz. weight and a
1.1 inch presser foot. Average of at least 2 readings was recorded
as the thickness in mils.
[0092] Bulk Density
[0093] Bulk density is calculated as .rho..sub.W=W/25.4 T where
.rho..sub.W is the bulk density in grams/cm3, W is the basis weight
in grams/m.sup.2 and T is the thickness in mils.
[0094] Abrasion Resistance
[0095] Samples were evaluated for abrasion resistance, as
determined by visual inspection, using a modified universal wear
test method. The method is based on ASTM standard D3886-92 and
consists essentially of abrading a sample with a selected abradent
and determining the number of cycles until a hole visually appears
through the test sample.
[0096] The sample is abraded using a Commercial Inflated Diaphragm
Abrasion Tester available through Custom Scientific Instruments in
Cedar Knolls, N.J. (model no. CS59-391). A one pound weight is used
along with a 4 psig inflation pressure to accelerate the wear. 600
grit sandpaper is used as the abradent. The abradent is replaced
every 150 cycles and at the start of a new sample.
[0097] Circular samples, 4.25 inches in diameter, of products of
this invention are placed on the tester with the side to be
abraded, i.e., the three dimensional material, facing up and a
contrasting color substrate below. The sandpaper is moved
horizontally across the surface of the sample in a back and forth
motion while the sample itself is being rotated 360 degrees to
ensure uniform wear in all directions. A single back and forth
motion is denoted as a "cycle".
[0098] The sample is evaluated for visual wear every 150 cycles
until a hole through the sample to the substrate is observed. The
point of the first sign of a hole is recorded as failure.
[0099] In case of non-woven samples, pilling and roping was
detected at an earlier stages. In case of composites, the surface
of the polymeric material was abraded until the underlying water
resistant portion of the composite became visible.
[0100] At least two specimens were tested and the abrasion
resistance is reported as the average number of abrasion cycles
required for the specimens to fail.
[0101] Air Permeability
[0102] Carrier substrates were evaluated for air permeability using
a test method based on ISO 9237-1995E on a TexTest FX330 air
permeability tester. The test method was to cut a sample which
covered the 60 mm diameter test aperture. After clamping the sample
in the machine, an air pressure of 100 Pa is applied to the bottom
side of the sample and the volume of air passing through the sample
in a given time is measured. This flow rate is recorded and
reported in cm3/cm.sup.2/sec.
[0103] At least two specimens were tested and the air permeability
is reported as the average value.
[0104] Stretch and Recovery
[0105] The stretch and recovery properties was measured using an
Instron Model 5500R tensile testing machine. 1 inch wide and 6
inches long specimens were cut from the sample in the machine and
in the transverse directions. Two marks were placed 2 inches apart
in the long direction of the specimen. All the specimens were
simultaneously mounted on the testing machine with the test grips
spaced 3 inches apart. The crosshead is then extended by 1.5 inches
at a rate of 10 inches/min to stretch the specimen by 50%. If the
any of the specimens did not break, the sample was deemed to be
capable of stretching at least 50% of its length. The specimens
were held in the stretched state for 5 minutes and the cross head
was then returned to the position at the start of the test. The
relaxed specimens were then removed from the grips and after
waiting for at least 1 minute, the distance (D) between the marks
was measured. Per cent recovery was calculated as % recovery=100
(2-D/2), where D is in inches.
[0106] If small pieces are tested, appropriate equipment can be
used.
[0107] At least 3 specimens were tested for each sample and the
average percent recovery is reported along with the sample
orientation.
[0108] Water Vapor Transmission Test
[0109] Water vapour transmission rate (MVTR), i.e.
water-vapour-permeabili- ty, was measured by placing approximately
70 ml of a solution consisting of 35 parts by weight of potassium
acetate and 15 parts by weight of distilled water into a 133 ml.
polypropylene cup, having an inside diameter of 6.5 cm at its
mouth. An expanded polytetrafluoroethylene (PTFE) membrane having a
minimum MVTR of approximately 85,000 g/m.sup.2/24 hrs. as tested by
the method described in U.S. Pat. No. 4,862,730 to Crosby and
available from W. L. Gore & Associates, Inc. of Newark, Del.,
was heat sealed to the lip of the cup to create a taut, leakproof,
microporous barrier containing the solution.
[0110] A similar expanded PTFE membrane was mounted to the surface
of a water bath. The water bath assembly was controlled at
23.degree. C. plus or minus 0.2.degree. C., utilising a temperature
controlled room and a water circulating bath. The sample to be
tested was allowed to condition at a temperature of 23.degree. C.
and a relative humidity of 50% prior to performing the test
procedure. Three samples were placed so that each sample to be
tested was in contact with the expanded PTFE membrane mounted over
the surface of the water bath, and was allowed to equilibrate for
at least 15 minutes prior to the introduction of the cup
assembly.
[0111] The cup assembly was weighed to the nearest 1/1000 g and was
inverted onto the centre of the text sample.
[0112] Water transport was provided by the driving force between
the water in the water bath 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, and
weighed again to within 0.001 g.
[0113] The MVTR 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.
[0114] At least two specimens were tested and the water vapor
transmission rate is reported as the average value.
[0115] Water Resistance Test
[0116] Samples of the materials were tested for water-proofness 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.
[0117] 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 was increased to 1 psi by a pump connected to a water
reservoir, as indicated by an appropriate gauge and regulated by an
in-line air valve.
[0118] 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.
[0119] Force to Flex (Hand)
[0120] The peak force required to flex a sample through a defined
geometric bend was measured. The device used was a Thwing-Albert
Handle-O-Meter, model 211-5-10. The Handle-O-Meter has a 1000 g
blade which forces a sample through a 0.25 inch wide slot having
parallel sides. The peak force required to achieve this deflection
is report in grams. This force is influenced by the friction
between the sample and the polished face of the machine.
[0121] Samples were die cut into ten 4 inch square specimens, five
of which were cut in the fill direction and five of which were cut
from the warp direction. Each sample was tested in each of its four
orientations: machine or cross-machine direction corresponding with
sample cut direction, and inner side up, in contact with the blade
or inner side down in contact with the slot. The peak load for each
orientation is recorded and the sum of all four is noted as the
`hand`. The average of 5 readings are reported.
[0122] Some of the above measurements, such as basis weight,
thickness, bulk density, stretch/recovery, ideally are independent
of sample size. Therefore, when adequate samples as per the
described test procedures are not available, these measurements may
be obtained from similar tests using smaller sample/specimen
size.
[0123] Accelerated UV-Weathering Exposure (QUV Exposure)
[0124] Samples are cut and placed into a QUV Weatherometer made by
Q-Panel Lab Products using UVA 340 bulbs at an intensity of 1.2
W/m2/nm (at the calibration wavelength of 340 nm). One QUV cycle
lasts 24 hrs and consists of 8 hrs of UV exposure at 60.degree. C.,
4 hrs of condensation at 50.degree. C., 8 hrs of UV exposure at
60.degree. C. and 4 hrs of condensation at 50.degree. C. Cycles
were repeated per protocol.
[0125] UV Color Shift
[0126] UV Color Shift is the measure of color change after QUV
exposure cycles. Samples (unexposed) are placed into the
SPECTRALTEST TM spectrophotometer made by Datacolor International
and their spectrum are read. This procedure is then repeated for
samples (after exposure) and a color shift representing the
difference from the unexposed to exposed is calculated. (+) Delta
B* is the shift specifically in the yellow direction and is the
value reported.
[0127] UV Tensile Break Retention
[0128] UV Tensile Break Retention is the measure of the loss of
elasticity due to UV exposure/degradation. It was measured using a
Instron Model 5500R tensile testing machine. 1 inch wide and 6
inches long specimens were cut from the sample in the machine and
in the transverse directions. All the specimens were mounted on the
testing machine with the test grips spaced 3 inches apart. The
crosshead is then extended at a rate of 20 inches/min to stretch
the specimen until break. [L(final)/L(initial)-1]*1- 00 is noted as
the % tensile break elongation (unexposed). An average of a minimum
of 3 specimens is recorded. Samples from the same web undergo the
pre determined number of QUV exposure cycles and are then tested
again for % tensile break elongation (after exposure) using the
fore mentioned procedure. UV Tensile Break Retention is then
calculated as follows and reported as such.
UV Tensile Break Retention=break elongation (after Exposure)/break
elongation (unexposed)*100.
EXAMPLES
[0129] The following examples illustrate embodiments of the
invention, but are not intended to limit the scope of the present
invention.
Example 1
[0130] A thermoplastic polyurethane, TPU1, was synthesized from
4,4'-diphenylmethane diisocyanate (MDI)/1000 molecular weight
polycaprolactone diol (PCL1000)/1,4-butane diol in the molar
equivalents of 2:1:1.12 respectively using conventional
polyurethane prepolymer-type synthesis technique and then converted
into pellets. The resulting TPU1 has a hardness of 85 Shore A
hardness, a break elongation in excess of 400% and a melt flow
index of about 140 grams/10 minute (at 195.degree. C., 5 kg.). TPU1
was used to create the fibrous polymeric material of the invention
through a melt blowing technique.
[0131] A 20 inches wide horizontal melt blowing die with 0.0145
inches diameter orifices arranged in a single row with a spacing of
25 holes per inch was used. TPU1, in pellet form, was fed into a
single screw extruder. The extruder temperature profile was
maintained at a steady ramp profile, from the feed zone at
350.degree. F. up to the end zone at 460.degree. F. The melt was
fed into the die, maintained at 415.degree. F., at a throughput of
0.92 g/min/hole. The die nose piece was setback by 0.060 inches and
the air gap was set at 0.060 inches. The air temperature was
maintained at 440.degree. F. at an air volume of 590 cfm.
[0132] Above conditions were used to melt blow TPU1 on to a 3.4
oz./yd.sup.2 woven fabric with an air permeability of 9.75
cm3/cm.sup.2/sec moving over a collector at 26 feet/min. A vacuum
was applied at the collector which was located 10 inches from the
die.
[0133] Unless otherwise specified, the resulting fibrous polymeric
material was peeled from the woven fabric and tested for various
properties. The results, summarized in Table 1, indicate the high
bulk density and the high abrasion resistance of the invented
material of this example.
Example 2
[0134] Using a 47" wide vertical meltblowing die, TPU1 was
converted into the polymeric material of this invention under
conditions similar to that described in example 1. The melt blown
TPU1 material was collected on a 4.4 oz/yd.sup.2 woven fabric with
an air permeability of 47 cm3/cm.sup.2/sec. The material was then
peeled off from the woven fabric and tested for various properties.
The results are summarized in Table 1. The results indicate the
high bulk density and the high abrasion resistance of the invented
material of this example.
Examples 3-7
[0135] TPU1 was melt blown on to various woven fabrics to create
the polymeric material of the invention of different basis weights.
The procedure used was similar to that described in example 2. The
resulting materials were peeled off from the woven fabric carriers
and tested for various properties. The results are listed in Table
1. It is seen that, though structurally similar, the bulk density
and the abrasion resistance of the invented material depend on the
basis weight.
Comparative Examples 1-9
[0136] Various commercially available elastomeric non-woven fabrics
were obtained, tested for properties and compared with the
properties of the polymeric material of this invention. The results
of these commercial non-woven fabrics are summarized in Table 2. It
is seen that, in comparison to the invented material, these
comparative samples are low in both bulk density and abrasion
resistance.
Example 8
[0137] A water resistant, air impermeable and water vapor permeable
substrate was made by coating ePTFE film of 18 g/m.sup.2 weight
with a 12 gm/m.sup.2 layer of a hydrophilic polyurethane as
described in U.S. Pat. No. 4,194,041. The substrate was then
adhered to the polymeric material of example 3 on the ePTFE side
using a dot pattern of polyurethane adhesive as described in U.S.
Pat. No. 4,532,316 to create a water vapor permeable, water
resistant composite. The composite was tested for various
properties and the results are listed in Table 3.
Comparative Example 10
[0138] A composite similar to that described in Example 8 was made
except that a 4 oz/yd.sup.2 woven Cordura fabric was used in place
of the polymeric material of this invention. The properties of the
resulting composite are provided in Table 3. The results of Example
8 & Comparative Example 10 indicate the improved hand and
abrasion resistance offered to the composite by the material of
this invention as compared to a woven fabric of similar weight.
Example 9
[0139] To the available hydrophilic coating side of the composite
of Example 8, a 1.3 oz/yd.sup.2 knitted fabric was adhered using a
dot pattern of polyurethane adhesive. The composite was tested for
various properties and the results are listed in Table 3.
Comparative Example 11
[0140] A composite similar to that described in Example 9 was made
except that a 4 oz/yd.sup.2 woven Cordura fabric was used in place
of the polymeric material of this invention. The properties of the
resulting composite are provided in Table 3. The results of Example
9 & Comparative Example 11 indicate the improved hand and
abrasion resistance offered to the composite by the material of
this invention as compared to a woven fabric of similar weight.
Example 10
[0141] A thermoplastic polyurethane, TPU2, was synthesized from
dicyclohexylmethane-4,4'-diisocyanate/2000 molecular weight
polycaprolactone diol (PCL2000)/1,4-butane diol in the molar
equivalents of 2:0.44:1.65 respectively using conventional
polyurethane prepolymer-type synthesis technique and then converted
into pellets. The resulting TPU2 has a hardness of 88 Shore A
hardness, a break elongation in excess of 2000% and a melt flow
index of about 188 grams/10 minute (at 195.degree. C., 5 kg.). TPU2
was used to create the fibrous polymeric material of the invention
through a melt blowing technique similar to Example #1.
[0142] The web of this example shows the versatility of the
invention so long as the polymer has appropriate characteristics.
In this instance, a web with a higher degree of resistance to UV
degradation was sought while maintaining the other aspects of the
invention such as abrasion resistance, softness, density and air
permeability. Table 1 shows properties of Example #10 to be similar
to webs of the invention with comparable basis weights (Examples
#1-5). However, Table 4 shows this web to have a much higher
resistance to degradation due to UV exposure. This is demonstrated
by the measured resistance to yellowing and by "the retention of
break elongation, both of which are superior to a web of TPU1.
1 TABLE 1 Abrasion Recovery from Weight Thickness Bulk Density
Resistance, 50% Stretch Air Permeability gm/m.sup.2 mils gm/cm3
Cycles % MD % TD cm3/cm2/sec Example 1 128 10.5 0.48 2333 96 96 18
Example 2 132 10.3 0.50 2037 -- -- 17.3 Example 3 133 10 0.52 1715
-- -- 13.3 Example 4 125 11.8 0.42 1295 96 95 27.1 Example 5 118
8.25 0.56 3808 -- -- 13.8 Example 6 73 8 0.36 375 -- -- 32.7
Example 7 79 7.25 0.43 275 -- -- 21.2 Example 10 111 10 0.41 1200
-- -- 23.3
[0143]
2TABLE 2 Properties of Commercially Available Elastomeric Non-woven
Fabrics Abrasion Weight Thickness Bulk Density Resistance, Sample
gm/m.sup.2 mils gm/cm3 Cycles Comparative Example 1 UHO180.sup.1
181 24.8 0.287 680 Comparative Example 2 UHO150.sup.1 149 23.8
0.246 180 Comparative Example 3 UHO125.sup.1 125 20.0 0.246 120
Comparative Example 4 UHO85.sup.1 85 15.0 0.223 60 Comparative
Example 5 UHO50.sup.1 50 10.0 0.197 25 Comparative Example 6
FHO85.sup.1 85 14.0 0.239 58 Comparative Example 7 TPU.sup.2 114
12.5 0.359 33 Comparative Example 8 Septon.sup.2 108 16.3 0.261 10
Comparative Example 9 2 oz./yd.sup.2 67 12.5 0.211 9 Demique .RTM.
.sup.3 .sup.1from Kanebo Corporation, Japan. .sup.2from Kurary
Corporation, Japan. .sup.3from Kimberly-Clark Corporation, Neenah,
WI.
[0144]
3 TABLE 3 Abrasion WVTR resistance, Hand gm/day/m.sup.2 cycles
grams Example 8 10,974 3933 266 Example 9 5,284 4150 598
Comparative Example 10 13,253 693* 703 Comparative Example 11 6,194
430* 1485 woven fabric side abraded
[0145]
4 TABLE 4 Color Shift Tensile Break Elongation (+) delta B*
Retention % (1 cycle) (1 cycle 5 cycle 10 cycle 25 cycle) Example 1
66.5 29 10 6 5 Example 10 2.11 86 33 13 0
* * * * *