U.S. patent application number 15/336905 was filed with the patent office on 2017-02-16 for conformable microporous fiber and woven fabrics containing same.
The applicant listed for this patent is W. L. Gore & Associates, Inc.. Invention is credited to David J. Minor, Raymond B. Minor.
Application Number | 20170044696 15/336905 |
Document ID | / |
Family ID | 51454972 |
Filed Date | 2017-02-16 |
United States Patent
Application |
20170044696 |
Kind Code |
A1 |
Minor; David J. ; et
al. |
February 16, 2017 |
Conformable Microporous Fiber and Woven Fabrics Containing Same
Abstract
Expanded polytetrafluoroethylene (ePTFE) monofilament fibers and
woven fabrics formed from the ePTFE fillers are provided, The ePTFE
fibers have a substantially rectangular configuration, a density
less than about 1.0 glee, and an aspect ratio greater than 15.
Additionally, the ePTFE fibers are microporous and have a node and
fibril structure. The ePTFE fiber may be woven into a fabric
without first twisting the fiber. A polymer membrane and/or a
textile may be laminated to the woven fabric to produce a laminated
article. The ePTFE woven fabric simultaneously possesses high
moisture vapor transmission (highly breathable) and high water
entry pressure (water resistant). The woven fabric is quiet, soft,
and drapable, making it especially suitable for use in garments,
gloves and footwear applications. Treatments may be provided to the
surface of the ePTFE fiber and/or the woven fabric to impart one or
more desired functionality, such as, for example,
oleophobicity).
Inventors: |
Minor; David J.; (Elkton,
MD) ; Minor; Raymond B.; (Elkton, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
W. L. Gore & Associates, Inc. |
Newark |
DE |
US |
|
|
Family ID: |
51454972 |
Appl. No.: |
15/336905 |
Filed: |
October 28, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14029250 |
Sep 17, 2013 |
|
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15336905 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D03D 1/0035 20130101;
D01D 5/253 20130101; Y10T 442/3106 20150401; Y10T 428/2935
20150115; A41D 19/0006 20130101; A41D 2500/20 20130101; D03D 13/008
20130101; Y10T 428/2975 20150115; D10B 2501/04 20130101; Y10T
428/2922 20150115; D01F 6/12 20130101; A43B 7/125 20130101; D01D
5/247 20130101; D10B 2321/042 20130101; A41D 31/102 20190201; D03D
15/0088 20130101; Y10T 442/227 20150401; D03D 15/0083 20130101 |
International
Class: |
D03D 15/00 20060101
D03D015/00; A43B 7/12 20060101 A43B007/12; A41D 19/00 20060101
A41D019/00; D01F 6/12 20060101 D01F006/12; D01D 5/253 20060101
D01D005/253; D03D 1/00 20060101 D03D001/00; D03D 13/00 20060101
D03D013/00; A41D 31/02 20060101 A41D031/02; D01D 5/247 20060101
D01D005/247 |
Claims
1. A woven fabric comprising: a plurality of warp fibers and weft
fibers, each said warp fibers and each said weft fibers comprising
expanded polytetrafluoroethylene (ePTFE) fibers having a
substantially rectangular cross sectional configuration, wherein a
pre-woven width of said ePTFE fiber is greater than a width
allotted to said ePTFE fiber based on an end count or pick count of
said woven fabric.
2. The woven fabric of claim 1, wherein said ePTFE fibers are
monofilament fibers,
3. The woven fabric of claim 1, wherein said ePTFE fibers have a
density less than about 1.2 g/cm.sup.3.
4. The woven fabric of claim 1, wherein said ePTFE fibers have a
pre weaving density less than about 0.85 g/cm.sup.3.
5. The woven fabric of claim 1, wherein said ePTFE fibers have
nodes and fibrils defining passageways through said fiber, and
wherein said fibrils have a length from about 5 microns to about
120 microns.
6. The woven fabric of claim 1, wherein said woven fabric has an
air permeability less than about 5 cfm.
7. The woven fabric of claim 5, wherein said woven fabric has a
moisture vapor transmission rate greater than about 10,000
g/m.sup.2/24 hours.
8. The woven fabric of claim 1, wherein said woven fabric has a
water pick-up less than about 30 gsm.
9. The woven fabric of claim 1, wherein said ePTFE. fibers have an
aspect ratio greater than about 15.
10. The woven fabric of claim 1, wherein said ePTFE fibers have a
weight per length of less than about 500 dtex.
11. The woven fabric of claim 1, wherein said woven fabric has an
average stiffness of less than about 300 g.
12. The woven fabric of claim 1, wherein said woven fabric has a
weight per unit area of less than about 300 g/m.sup.2.
13. The woven fabric of claim 1. wherein said woven fabric has a
tear strength of at least 30 N.
14. The woven fabric of claim 1, wherein said woven fabric has an
average water entry pressure greater than about 1 kPa.
15. The woven fabric of claim 1, wherein said warp fibers and said
weft fibers have a fluoroacrylate coating to render said woven
fabric oleophobic.
16. The woven fabric of claim 15, further comprising a functional
membrane affixed to said warp and said weft fibers on a side
opposing said fiuoroacrylate coating.
17. The woven fabric of claim 16, further comprising a textile
affixed to said functional membrane.
18. The woven fabric of claim 15, further comprising a textile
affixed to said warp fibers and weft fibers on a side opposing said
fluoroacrylate coating.
19. The woven fabric of claim 1, further comprising at least one of
a textile and a functional membrane affixed to said woven
fabric.
20. The woven fabric of claim 1, wherein said woven fabric is in
the form of a garment, a glove, or footwear.
21. A woven fabric comprising: a plurality of warp fibers and weft
fibers, each said warp fibers and said weft fibers comprising
expanded polytetrafluoroethylene (ePTFE) fibers having a density
less than about 1.2 g/cm.sup.3 and a substantially rectangular
cross sectional configuration.
22. The woven fabric of claim 21, wherein said ePTFE fibers are
monofilament fibers.
23. The woven fabric of claim 21, wherein said woven fabric has a
water entry pressure greater than about 1 kPa.
24. The woven fabric of claim 21, wherein said woven fabric has a
moisture vapor transmission rate greater than about 10,000
g/m.sup.2/24 hours.
25. The woven fabric of claim 21, wherein said fabric has a water
pick-up less than about 30 gsm.
26. The woven fabric of claim 21, wherein said fabric has a weight
per unit area less than about 300 g/m.sup.2.
27. The woven fabric of claim 21, wherein at least one of said warp
and well fibers has an aspect ratio greater than about 15.
28. The woven fabric of claim 21, wherein said woven fabric has an
air permeability less than about 5 cfm.
29. The woven fabric of a claim 21, wherein each said warp and said
weft fibers have a pre-weaving thickness of less than about 100
microns and a pre-weaving width of less than about 4.0 mm.
30. The woven fabric of claim 29, wherein said width of said warp
and said weft fibers is greater than a width allotted to said
expanded polytetrafluoroethylene fibers based on an end count or a
pick count of said woven fabric.
31. The woven fabric of claim 21, wherein said expanded
polytetrafluoroethylene fibers have a pre-weaving density less than
about 0.85 g/cm.sup.3.
32. The woven fabric of claim 21, wherein said woven fabric has an
average stiffness of less than about 300 g.
33. The woven fabric of claim 21, wherein said woven fabric has a
tear strength of at least 30 N.
34. The woven fabric of claim 21. Wherein said warp fibers and said
weft fibers have a fluoroacrylate coating to render said woven
fabric oleophobic.
35. The woven fabric of claim 34, further comprising a functional
membrane affixed to said warp fibers and said weft fibers on a side
opposing said fluoroacrylate coating.
36. The woven fabric of claim 35. further comprising a textile
affixed to said functional membrane.
37. The woven fabric of claim 34, further comprising a textile
affixed to said warp fibers and well fibers on a side opposing said
fluoroacrylate coating.
38. The woven fabric of claim 21, further comprising at least one
of a textile and a functional membrane affixed to said woven
fabric.
39. The woven fabric claim 21, wherein said ePTFE fibers have a
node and fibril structure defining passageways through said fibers,
said fibrils having a length from about 5 microns to about 120
microns.
40. The woven fabric claim 21, wherein said woven fabric is in the
form of a garment, a glove, or footwear.
41. A woven fabric comprising: warp and weft fibers comprising
expanded polytetrafluoroethylene (ePTFE) fibers having a
substantially rectangular cross-section configuration, wherein said
woven fabric has a water entry pressure greater than about 1 kPa,
and wherein said woven fabric has a moisture vapor transmission
rate greater than about 10,000 g/m.sup.2124 hours.
42. The woven fabric of claim 41, wherein said ePTFE fibers are
monofilament fibers.
43. The woven fabric of claim 41, wherein a pre-weaving density of
said expanded polytetrafluoroethylene fibers is less than about
0.85 g/cm.sup.3.
44. The woven fabric of claim 41, wherein said warp and weft fibers
have a pre-weaving thickness less than about 100 microns and a
pre-weaving width less than about 4.0 mm.
45. The woven fabric of claim 44, wherein said width of said
expanded polytetrafluoroethylene fibers is greater than a width
allotted to said expanded polytetrafluoroethylene fibers in said
woven fabric based on an end count or pick count of said woven
fabric.
46. The woven fabric of claim 41, wherein said expanded
polytetrafluoroethylene fibers are conformable such that in a woven
configuration, said expanded polytetrafluoroethylene fiber folds
upon itself.
47. The woven fabric of claim 41, wherein said woven fabric has an
average stiffness less than about 300 g.
48. The woven fabric of claim 41, wherein said woven fabric has an
air permeability less than about 5 cfm.
49. The woven fabric of claim 41, wherein said woven fabric has a
tear strength of at least 30 N. 50, The woven fabric of claim 41,
wherein said woven fabric has an average water entry pressure
greater than about 2 kPa.
51. The woven fabric of claim 41, wherein said fabric has a weight
per unit area less than about 300 g/m.sup.2.
52. The woven fabric of claim 41, wherein said warp fibers and said
weft fibers have a fluoroacrylate coating.
53. The woven fabric of claim 52, further comprising a functional
membrane affixed to said warp fibers and said weft fibers on a side
opposing said fluoroacrylate coating.
54. The woven fabric of claim 53, further comprising a textile
affixed to said functional membrane.
55. The woven fabric of claim 52, further comprising a textile
affixed to said warp fibers and said weft fibers on a side opposing
said fluoroacrylate coating.
56. The woven fabric of claim 41, further comprising at least one
of a textile and a functional membrane affixed to said woven
fabric.
57. The woven fabric of claim 41 wherein said expanded
polytetrafluoroethylene (ePTFE) fibers have a node and fibril
structure defining passageways through said fibers, said fibrils
having a length from about 5 microns to about 120 microns.
58. The woven fabric of claim 57, wherein said ePTFE fibers are
monofilament fibers.
59. The woven fabric of claim 41, wherein said woven fabric is in
the form of a garment, a glove, or footwear.
60. A woven fabric comprising: warp and weft fluoropolymer fibers
having a length and a width, at least one of said warp and said
weft fluoropolymer fibers being in a folded configuration along
said length of said fiber.
61. The woven fabric of claim 60, wherein said woven fabric has a
moisture vapor transmission rate greater than about 10,000
g/m.sup.2/24 hours and a water entry pressure greater than about 1
kPa.
62. The woven fabric of claim 60, wherein said fluoropolymer fibers
have a weight per length of less than about 500 dtex.
63. The woven fabric of claim 60, wherein said fluoropolymer fibers
have an aspect ratio greater than about 15.
64. The woven fabric of claim 60, wherein said fluoropolymer fibers
are conformable such that in a woven configuration, said
fluoropolymer fibers fold upon themselves.
65. The woven fabric of claim 60, wherein said fluoropolymer fibers
are monofilament fibers having a porous microstructure.
66. The woven fabric of claim 60, wherein said fluoropolymer fibers
have nodes and fibrils defining passageways through said fiber, and
wherein said fibrils have a length from about 5 microns to about
120 microns.
67. The woven fabric of claim 60, wherein said fluoropolymer fibers
are expanded polytetrafluoroethylene (ePTFE) fibers.
68. The woven fabric of claim 67, wherein said ePTFE fibers have a
density less than about 1.2 g/cm.sup.3.
69. The woven fabric of claim 67, wherein said ePTFE fibers are
monofilament fibers.
70. The woven fabric of claim 67, wherein said ePTFE fibers have a
pre-weaving density less than about 0.85 g/cm.sup.3.
71. The woven fabric of claim 67, wherein said width of said ePTFE
fibers is greater than a width allotted to said ePTFE fibers in
said woven fabric based on an end count or a pick count of said
woven fabric.
72. The woven fabric of claim 67, wherein said ePTFE fibers have a
pre-weaving width less than about 4.0 mm and a pre-weaving
thickness less than about 100 microns.
73. The woven fabric of claim 67, wherein said woven fabric has a
water pick-up less than about 30 gsm.
74. The woven fabric of claim 67, wherein said ePTFE fibers have an
aspect ratio greater than about 15.
75. The woven fabric of claim 67, wherein said woven fabric has an
average stiffness of less than about 300 g.
76. The woven fabric of claim 67, wherein said woven fabric has an
air permeability less than about 5 cfm.
77. The woven fabric of claim 67, wherein said woven fabric has a
weight per unit area of less than about 300 g/m.sup.2.
78. The woven fabric of claim 67, wherein said warp fibers and said
weft fibers have a fluoroacrylate coating.
79. The woven fabric of claim 78, further comprising a functional
membrane affixed to said warp fibers and said well fibers on a side
opposing said fluoroacrylate coating.
80. The woven fabric of claim 79, further comprising a textile
affixed to said functional membrane.
81. The woven fabric of claim 78, further comprising a textile
affixed to said warp fibers and said well fibers on a side opposing
said fluoroacrylate coating.
82. The woven fabric of claim 67, further comprising at least one
of a textile and a functional membrane affixed to said woven
fabric.
83. The woven fabric of claim 67, wherein said ePTFE fibers have a
break strength of at least about 1.5 N.
84. The woven fabric of claim 67, wherein said fabric is in the
form of a garment, a glove, or footwear.
85. A woven fabric comprising warp and weft fluoropolymer fibers
having a node and fibril structure defining passageways through
said fiber, said fluoropolynier fibers being microporous, wherein
said woven fabric has an air permeability less than about 5 cfm and
a moisture vapor transmission rate greater than about 10,000
g/m.sup.2/24 hours.
86. The woven fabric of claim 85, wherein said fluoropolymer fibers
are expanded polytetrafluoroethylene fibers.
87. The woven fabric of claim 87, wherein said expanded
polytetrafluoroethylene fibers have a pre-weaving density of less
than about 0.85 g/cc.
88. The woven fabric of claim 85, wherein said woven fabric has a
water entry pressure greater than about 1 kPa.
89. The woven fabric of claim 85, wherein said fabric has a water
pick-up less than about 30 gsm.
90. The woven fabric of claim 85, wherein said fabric has a weight
per unit area of 300 g/m.sup.2.
91. The woven fabric of claim 85, wherein at least one of said warp
and weft fluoropolymer fibers has an aspect ratio greater than
about 15.
92. The woven fabric of a claim 85, wherein each said warp and said
weft fluoropolymer fibers have a pre-weaving thickness less than
about 100 microns and a width less than about 4.0 mm.
93. The woven fabric of claim 85, wherein said width is greater
than a width allotted to the fluoropolymer fiber based on an end
count or a pick count of said woven fabric.
94. The woven fabric of claim 85, wherein said woven fabric has an
average stiffness of less than about 300 g.
95. The woven fabric of claim 85, wherein said woven fabric has a
tear strength of at least 30 N.
96. The woven fabric of claim 85, wherein said fibrils have length
from about 5 microns to about 120 microns.
97. The woven fabric of claim 85, further comprising at least one
of a textile and a fluoropolymer membrane affixed to said woven
fabric.
98. The woven fabric of claim 85, wherein said woven fabric is in
the form of a garment, a glove, or footwear.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to conformable
microporous fibers, and more specifically, to conformable
microporous fibers having a node and fibril structure that are
highly breathable. Woven fabrics containing the conformable
microporous fibers are also provided.
BACKGROUND OF THE INVENTION
[0002] Waterproof, breathable garments are well-known in the art,
These garments are often constructed from multiple layers in which
each layer adds a certain functionality. For example a garment
could be constructed using an outer textile layer, a waterproof,
breathable film layer, and an inner textile layer. The outer and
inner textile layers provide protection to the breathable film
layer. However, the addition of outer and inner fabric layers not
only adds weight to an article of apparel, it also results in
materials having the potential for a high water pick-up on the
outer surface. The pick-up of water by the outer fabric layer
permits for thermal conductivity and the passage of the temperature
of the water through the fabric and to the wearer. This may be
detrimental in eases where the wearer is in a cold environment and
the cold is transported to the body of the wearer. In addition,
water pick-up may lead to condensation on the inside of the
garment, making the wearer feel wet. Further, the color of the
outer fabric may become discolored or darken upon water pick-up,
thus reducing the aesthetic appearance of the garment. Also,
depending on the outer fabric, there may be a long dry time
associated with the fabric itself, forcing the wearer to endure the
disadvantages associated with the water pick-up for a longer time.
Additionally, the fibers associated with conventional fabrics used
in the inner and outer layer are constructed of multifilament
fibers, which permit water and/or contaminants between the
filaments. Additionally, because multifilament fibers are loosely
packed for breathability in the fabric, water can undesirably fill
the space between the fibers.
[0003] Thus, there exists a need in the art for a fiber to make
woven fabrics for use in garments that is highly breathable, has a
high water entry pressure, and has a low water pick-up.
SUMMARY OF THE INVENTION
[0004] It is an object of the present invention to provide a woven
fabric that includes warp and weft expanded polytetrafluoroethylene
(ePTFE) fibers that have a microporous structure of nodes and
fibrils. where the width of the ePTFE fiber is greater than the
width allotted to the ePTFE fiber based on the end count or pick
count of the woven fabric. This difference in width causes the
ePTFE fiber to fold upon itself to conform to the weave spacing
provided between the crossovers of the warp and weft fibers. The
ePTFE fibers may be monofilament fibers. The ePTFE fibers may have
a density less than about 1.2 g/cm.sup.3, an aspect ratio greater
than about 15, and a substantially rectangular cross sectional
configuration. Advantageously, the ePTFE woven fabric possesses
both a high moisture vapor transmission and a high water entry
pressure. In particular, the woven fabric has a moisture vapor
transmission rate greater than about 10,000 g/m.sup.2/24 hours and
a water entry pressure greater than about 1 kPa. Thus, the woven
fabric is highly breathable, has a low water pick-up, and is highly
water resistant.
[0005] It is another object of the present invention to provide a
woven fabric that includes a plurality of warp and weft fibers
where each of the warp and weft fibers include expanded
polytetrafluoroethylene fibers that have a density less than about
1.2 g/cm.sup.3 and a substantially rectangular cross sectional
configuration. The ePTFE fibers may be monofilament fibers. At
least one of the warp and well ePTFE fibers may have an aspect
ratio greater than about 15. In at least one exemplary embodiment,
the width of the ePTFE fibers is greater than the number of picks
per inch of the woven fabric. Further, the woven fabric has an
average stiffness less than about 300 g and a water pick-up less
than 30 gsm. The warp fibers and weft fibers may have a
fluoroacrylate coating to render the woven fabric oleophobic. A
fluoropolymer membrane, or other functional membranes or protective
layer, may be affixed to the woven fabric on a side opposing the
fluoroacrylate coating. In some embodiments, a textile may be
affixed to the fluoropolymer membrane to form a laminated article.
In other embodiments, a fluoropolymer membrane and/or a textile may
be affixed to the woven fabric without the application of a
coating.
[0006] It is a further object of the invention to provide a woven
fabric that includes warp and weft fibers of expanded
polytetrafluoroethylene fibers having an aspect ratio greater than
about 15 and a substantially rectangular cross-section
configuration. The woven fabric has a water entry pressure greater
than about 1 kPa and a moisture vapor transmission rate greater
than about 10,000 g/m.sup.2/24 hours. The ePTFE fibers may be
monofilament fibers. Additionally, the fibers may have a
pre-weaving thickness less than about 100 microns, a pre-weaving
width less than about 4.0 mm, and a pre-weaving density less than
about 1.0 g/cm.sup.3. Further, the ePTFE fibers have a node and
fibril structure where the nodes are interconnected by fibrils that
define passageways through the fiber. The fibrils may have a length
from about 5 microns to about 120 microns.
[0007] It is yet another object of the invention to provide a woven
fabric that includes warp and welt fluoropolymer fibers where at
least one of the warp and weft fluoropolymer fibers is in a folded
configuration along a length of the fiber. In at least one
exemplary embodiment, the fluoropolymer fibers are ePTFE fibers
that have a density less than about 1.2 g/cm.sup.3 and have a
substantially rectangular configuration. In exemplary embodiments,
the ePTFE fibers have a pre-weaving density less than about 0.85
g/cm.sup.3). The woven fabric has a moisture vapor transmission
rate greater than about 10,000 g/m.sup.2/24 hours and a water entry
pressure greater than about 1 kPa. In addition, the woven fabric
has a tear strength of at least 30 N and an average stiffness of
less than about 300 g. In at least one exemplary embodiment, the
width of the fluoropolymer fiber is greater than the width allotted
to the fluoropolymer fiber in the woven fabric based on the end
count or pick count of the woven fabric.
[0008] It is also an object of the present invention to provide a
woven fabric that includes conformable warp and weft fluoropolymer
fibers where at least one of the warp and weft fibers have a node
and fibril structure that form passageways through the fiber. The
fibrils may have a length from about 5 microns to about 120
microns. In at least one embodiment, the fluoropolymer fibers are
ePTFE fibers that have a pre-weaving density less than about 1.0
g/cm.sup.3, and in other embodiments, less than about 0.85
g/cm.sup.3. The conformability of the fiber permits the fiber to
curl and/or fold upon itself to conform to weave spacing provided
between the crossovers of the warp and weft fibers in a woven
configuration. Additionally, a functional membrane or protective
layer, such as a fluoropolymer membrane, may be affixed to the
ePTFE woven fabric. In some embodiments, a textile is affixed to
the fluoropolymer membrane to form a laminated article.
[0009] It is yet another object of the present invention to provide
a monofilament fiber that includes expanded
polytetrafluoroethylene. The ePTFE monofilament fiber has a density
less than or equal to 1.0 g/cm.sup.3, a thickness less than about
100 microns, a width less than about 4.0 mm, an aspect ratio
greater than about 15, and a substantially rectangular
cross-section configuration. In addition, the fiber has a tenacity
greater than about 1.6 cN/dtex and a break strength of at least
about 1.5 N. The ePTFE monofilament fiber may have thereon a
fluoroacrylate coating, or other oleophobic treatment.
Additionally, the ePTFE monofilament fibers have a node and fibril
configuration where the nodes and fibrils define passageways
through the fiber. The fibril length may be from about 5 microns to
about 120 microns. Further, the ePTFE monofilament fiber is
conformable such that in a woven configuration, the ePTFE
monofilament fiber folds upon itself to conform to weave spacing
provided between the crossovers of the warp and weft fibers in the
woven fabric. Such ePTFE monofilament fibers are utilized in
exemplary embodiments of the invention to form woven fabrics that
may ultimately be used in an article that demands high moisture
vapor transmission and high water entry pressure (i.e., high
breathability and high resistance to water).
[0010] It is an advantage of the present invention that even when
the ePTFE fiber is tightly woven, the ePTFE woven fabric is highly
breathable and has a high water entry pressure.
[0011] It is another advantage of the present invention that the
ePTFE fibers may be tightly woven into a woven fabric that is
highly breathable yet possesses a low air permeability.
[0012] It is also an advantage of the present invention that the
woven fabric is quiet, soft, and drapable.
[0013] It is yet another advantage of the present invention that
the high aspect ratio of the ePTFE fibers enables low weight per
area fabric, easier and more efficient reshaping, and can achieve
high water resistance in a woven fabric with less picks and ends
per inch.
[0014] It is a feature of the present invention that the ePTFE
fibers curl and/or fold upon themselves to conform to the weave
spacing provided between the crossovers of the warp and weft fibers
in the woven fabric.
[0015] It is also a feature of the present invention that woven
fabrics constructed from the ePTFE fibers have a flat or
substantially flat weave and a corresponding smooth surface.
[0016] It is another feature of the present invention that the
ePTFE fibers have a substantially rectangular cross-section
configuration, particularly prior to weaving.
BRIEF DESCRIPTIONS OF FIGURES
[0017] The advantages of this invention will be apparent upon
consideration of the following detailed disclosure of the
invention, especially when taken in conjunction with the
accompanying drawings wherein:
[0018] FIG. 1 is a scanning electron micrograph (SEM) of the top
surface of an exemplary ePTFE fiber taken at 1000.times.
magnification according to one exemplary embodiment of the
invention;
[0019] FIG. 2 is a scanning electron micrograph of a side of the
ePTFE fiber depicted in FIG. 1 taken at 1000.times.
magnification:
[0020] FIG. 3 is scanning electron micrograph of the top surface of
a 2/2 woven twill fabric of the fiber depicted in FIG. 1 taken at
150.times. magnification;
[0021] FIG. 4 is a scanning electron micrograph of a side of the
woven fabric depicted in FIG. 3 taken at 150.times.
magnification;
[0022] FIG. 5 is a scanning electron micrograph of the top surface
of the 2/2 woven twill fabric depicted in FIG. 3 having thereon a
fluoroacrylate coating taken at 150.times. magnification:
[0023] FIG. 6 is a scanning electron micrograph of a side of the
woven fabric depicted in FIG. 5 taken at 150.times.
magnification;
[0024] FIG. 7 is a scanning electron micrograph of the top surface
of the 2/2 woven twill fabric illustrated in FIG. 5 having
laminated thereto an ePTFE membrane taken at 150.times.
magnification;
[0025] FIG. 8 is a scanning electron micrograph of a side of the
article depicted in FIG. 7 taken at 100.times. magnification;
[0026] FIG. 9 is a scanning electron micrograph of a side of the
fabric depicted in FIG. 7 taken at 1000.times. magnification;
[0027] FIG. 10 is a scanning electron micrograph of the top surface
of the woven fabric illustrated in FIG. 5 laminated to a textile
taken at 150.times. magnification according to another exemplary
embodiment of the invention;
[0028] FIG. 11 is a scanning electron micrograph of a side of the
article depicted in FIG. 10 taken at 100.times. magnification;
[0029] FIG. 12 is a scanning electron micrograph of a side of the
article depicted in FIG. 10 taken at 500.times. magnification;
[0030] FIG. 13 a scanning electron micrograph of the top surface of
a woven fabric having laminated thereto an ePTFE membrane and a
textile according to an exemplary embodiment of the invention taken
at 150.times. magnification:
[0031] FIG. 14 is a scanning electron micrograph of a side of the
article depicted in FIG. 13 taken at 100.times. magnification;
[0032] FIG. 15 is a scanning electron micrograph of a side of the
article depicted in FIG. 13 taken at 300.times. magnification;
[0033] FIG. 16 is a scanning electron micrograph of the top surface
of a plain woven fabric according to one exemplary embodiment of
the invention taken at 150.times. magnification;
[0034] FIG. 17 is a scanning electron micrograph of a side of the
fabric depicted in FIG. 16 taken at 250.times. magnification;
[0035] FIG. 18 is scanning electron micrograph of the top surface
of the plain woven fabric illustrated in FIG. 16 having thereon a
fluoroacrylate coating taken at 150.times. magnification;
[0036] FIG. 19 is a scanning electron micrograph of a side of the
woven fabric depicted in FIG. 18 taken at 250.times.
magnification;
[0037] FIG. 20 is a scanning electron micrograph of the top surface
of the woven fabric depicted in FIG. 16 having laminated thereto an
ePTFE membrane and a textile taken at 150.times. magnification
according to an exemplary embodiment of the invention;
[0038] FIG. 21 is a scanning electron micrograph of a side view of
the article depicted in FIG. 20 taken at 250.times.
magnification;
[0039] FIG. 22 is a scanning electron micrograph of the top surface
of an exemplary ePTFE fiber taken at 1000.times. magnification
according to another exemplary embodiment of the invention;
[0040] FIG. 23 is a scanning electron micrograph of a side of the
ePTFE fiber depicted in FIG. 22 taken at 1000.times.
magnification;
[0041] FIG. 24 is a scanning electron micrograph of the top surface
of a 2/2 twill fabric of the ePTFE fiber depicted in FIG. 22 taken
at 150.times. magnification;
[0042] FIG. 25 is a scanning electron micrograph of a side of the
fabric depicted in FIG. 24 taken at 200.times. magnification;
[0043] FIG. 26 is a scanning electron micrograph of the top surface
of the woven twill fabric depicted in FIG. 16 having thereon a
fluoroacrylate coating taken at 150.times. magnification;
[0044] FIG. 27 is a scanning electron micrograph of a side of the
fabric depicted in FIG. 26 taken at 200.times. magnification;
[0045] FIG. 28 is a scanning electron micrograph of the top surface
of an exemplary ePTFE fiber according to a further embodiment of
the invention taken at 1000.times. magnification;
[0046] FIG. 29 is a scanning electron micrograph of a side of the
fiber depicted in FIG. 28 taken at 1000.times. magnification;
[0047] FIG. 30 is a scanning electron micrograph of the top surface
of a 2/2 twill woven fabric of the ePTFE fiber illustrated in FIG.
26 taken at 150.times. magnification;
[0048] FIG. 31 is a scanning electron micrograph of a side of the
fabric depicted in FIG. 30 taken at 150.times. magnification;
[0049] FIG. 32 is a scanning electron micrograph of the top surface
of a high density comparative ePTFE fiber taken at 1000.times.
magnification;
[0050] FIG. 33 is a scanning electron micrograph of a side of a
woven fabric of the fiber depicted in FIG. 32 taken at 1000.times.
magnification:
[0051] FIG. 34 is a scanning electron micrograph of the top surface
of a 2/2 twill woven comparative fabric utilizing a comparative
high density ePTFE fiber taken at 150.times. magnification;
[0052] FIG. 35 is a scanning electron micrograph of a side of the
fabric depleted in FIG. 34 taken at 150.times. magnification;
[0053] FIG. 36 is a scanning electron micrograph of a top surface
of an exemplary fiber taken at 1000.times. magnification;
[0054] FIG. 37 is a scanning electron micrograph of a side of the
fiber depicted in FIG. 36 taken at 1000.times. magnification;
[0055] FIG. 38 is a scanning electron micrograph of the top surface
of a woven fabric of the fiber shown in FIG. 36 taken at 150.times.
magnification:
[0056] FIG. 39 is a scanning electron micrograph of a side of the
fabric depicted in FIG. 38 taken at 150.times. magnification;
[0057] FIG. 40 is a schematic illustration depicting a side view of
exemplary fibers folding into a folded configuration to fit into
the space allotted to the fiber in the woven configuration;
[0058] FIG. 41 is a schematic illustration depicting a top view of
exemplary fibers folding into a folded configuration to fit into
the space allotted to the fiber in the woven configuration;
[0059] FIG. 42 is a scanning electron micrograph of the top surface
of an exemplary plain weave fabric with a 40.times.40 thread count
taken at 150.times. magnification:
[0060] FIG. 43 is a scanning electron micrograph of a side of the
woven fabric depicted in FIG. 42 taken at 150.times.
magnification;
[0061] FIG. 44 is a scanning electron micrograph of a side of the
woven fabric depicted in FIG. 42 taken at 300.times.
magnification;
[0062] FIG. 45 is a scanning electron micrograph of a side of the
woven fabric depicted in FIG. 42 taken at 400.times.
magnification;
[0063] FIG. 46 is a scanning electron micrograph of the top surface
of a comparative non-porous ePTFE fiber taken at 1000.times.
magnification;
[0064] FIG. 47 is a scanning electron micrograph of a side of the
fiber depicted in FIG. 46 taken at 1000.times. magnification;
[0065] FIG. 48 is a scanning electron micrograph of a woven fabric
of the fiber depicted in FIG. 46 taken at 150.times.
magnification;
[0066] FIG. 49 is a scanning electron micrograph of a side of the
woven fabric of FIG, 48 taken at 150.times. magnification;
[0067] FIG. 50 is a scanning electron micrograph of the top surface
of a comparative woven fabric of a comparative high density ePTFE
fiber taken at 150.times. magnification;
[0068] FIG. 51 is a scanning electron micrograph of a side surface
of the woven fabric illustrated in FIG. 50 taken at 150.times.
magnification; and
[0069] FIG. 52 is a scanning electron micrograph illustrating gap
width measurements.
DEFINITIONS
[0070] The terms "monofilament fiber" and "monofilament ePTFE
fiber" as used herein are meant to describe an ePTFE fiber that is
continuous or substantially continuous in nature which may he woven
into a fabric.
[0071] The terms "fiber" and "ePTFE fiber" as used herein are meant
to include monofilament ePTFE fibers as well as a plurality of
monofilament ePTFE fibers, such as, for example, fibers in a
side-by-side configuration, in a bundled configuration, or in a
twisted or otherwise intermingled form.
[0072] The term "conformable" and "conformable fiber" as used
herein are meant to describe fibers that are capable of curling
and/or folding upon themselves to conform to weave spacing provided
between the crossovers of the warp and weft fibers and as
determined by the number of picks per inch and/or ends per inch of
the warp and weft fibers.
[0073] "High water entry pressure" as used herein is meant to
describe a woven fabric with a water entry pressure greater than
about 1 kPa.
[0074] The phrase "low water pick-up" as used herein is meant to
denote a woven fabric having a water pick-up less than about 50
gsm.
[0075] The term "substantially rectangular configuration" as used
herein is meant to denote that the conformable, microporous fibers
have a rectangular or nearly rectangular cross section, with or
without a rounded or pointed edge (or side).
DETAILED DESCRIPTION OF THE INVENTION
[0076] The present invention relates to conformable microporous
fibers having a node and fibril structure and woven fabrics
produced therefrom. A polymer membrane and/or a textile may be
laminated to the woven fabric to produce a laminated article. The
woven fabric concurrently possesses high moisture vapor
transmission (i.e., highly breathable), high water entry pressure
and low water pick-up. The woven fabric can be colorized, such as,
for example, by printing. In addition, the woven fabric is quiet,
soft, and drapable, making it especially suitable for use in
garments, gloves, and in footwear applications. It is to be noted
that the terms "woven fabric" and "fabric" may be used
interchangeably herein. In addition, the terms "ePTFE fiber" and
"fiber", may be interchangeably used within this application.
[0077] The conformable fibers have a node and fibril structure
where the nodes are interconnected by fibrils, the space between
which defines passageways through the fibers. Also, the conformable
fibers are microporous. Microporous is defined herein as having
pores that are not visible to the naked eye. The node and fibril
structure within the fiber permits the fiber, and fabrics woven
from the fiber, to be highly breathable and allow for the
penetration of colorants and oleophobic compositions. Also, the
matrix provided by the nodes and fibrils allows for the inclusion
of desired fillers and/or additives.
[0078] It is to be appreciated that with respect to the
conformable, microporous fibers; reference is made herein with
respect to expanded polytetrafluorethylene (ePTFE) fibers for ease
of discussion. However, it is to be understood that any suitable
conformable fluoropolymer having a node and fibril structure may be
used interchangeably with ePTFE as described within this
application. Non-limiting examples of fluoropolymers include, but
are not limited to, expanded PTFE, expanded modified PTFE, expanded
copolymers of PTFE, fluorinated ethylene propylene (FEP), and
perfluoroalkoxy copolymer resin (PFA). Patents have been granted on
expandable blends of PTFE, expandable modified PTFE, and expanded
copolymers of PTFE, such as., but not limited to, U.S. Pat. No.
5,708,044 to Branca; U.S. Pat. No. 6,541,589 to Baillie; U.S. Pat.
No. 7,531,611 to Sabol et al.; U.S. patent application Ser. No.
11/906,877 to Ford; and U.S. patent application Ser. No. 12/410.050
to Xu et al. The fibril length of the ePTFE fibers ranges from
about 5 microns to about 120 microns, from about 10 microns to
about 100 microns, from about 15 microns to about 80 microns, or
from about 15 microns to about 60 microns.
[0079] Additionally, the ePTFE fibers have a substantially
rectangular configuration. At least FIGS. 4, 6, 12, 14, 17, 19, 21,
27, 30, 39, 43, 44, 45 of this application depict exemplary ePTFE
fibers having substantially rectangular configurations. As used
herein, the term "substantially rectangular configuration" is meant
to denote that the fibers have a rectangular or nearly rectangular
cross section. That is, the ePTFE fibers have a width that is
greater than its height (thickness). It is to be noted that the
fibers may have a rounded or pointed edge (or side). Unlike
conventional fibers that must be twisted prior to weaving, the
ePTFE fibers can be woven while in a flat state without having to
first twist the ePTFE fiber. The ePTFE fibers may be advantageously
woven with the width of the fiber oriented so that it forms the top
surface of the woven fabric. Thus, woven fabrics constructed from
the inventive ePTFE fibers have a flat or substantially flat weave
and a corresponding smooth surface. The smooth, planar surface of
the fabric enhances the softness of the woven fabric.
[0080] In addition, the ePTFE fibers used herein have a low
density. More specifically, the fibers have a pre-weaving density
less than about 1.0 g1cm.sup.3, In exemplary embodiments, the
fibers have a pre-weaving density less than about 0.9 g/cm.sup.3,
less than about 0.85 g/cm.sup.3, less than about 0.8 g/cm.sup.3,
less than about 0.75 g/cm.sup.3, less than about 0.7 g/cm.sup.3,
less than about 0.65 g/cm.sup.3, less than about 0.6 g/cm.sup.3,
less than about 0.5 g/cm.sup.3, less than about 0.4 g/cm.sup.3,
less than about 0.3 g/cm.sup.3, or less than about 0.2 g/cm.sup.3.
Processes used to make a fabric, such as weaving, fold the ePTFE
fibers and may increase the density of the fibers while preserving
breathability through the woven fabric. As a result, the fibers may
have a post-weaving density less than or equal to about 1.2
g/cm.sup.3. The low density of the fiber (both pre- and post-weave)
also enhances the breathability of the fiber,
[0081] Additionally, the fibers may have a weight per length of
about 50 dtex to about 3500 dtex, from about 70 dtex to about 1000
dtex, from about 80 dtex to about 500 dtex, from about 90 dtex to
about 400 dtex, from about 100 dtex to about 300 dtex, or from
about 100 dtex to about 200 dtex. It is to be appreciated that a
lower dtex provides a lower weight/area fabric, which enhances the
comfort of a garment formed from the fabric. In addition, the low
denier of the ePTFE fiber enables the woven fabric to have a high
pick resistance. Pick resistance is referred to as the ability of a
fabric to resist the grasping and moving of individual fibers
within the fabric. In general, the finer the fiber (e.g,, lower
denier or dtex) and tighter the weave, a better pick resistance is
achieved.
[0082] The ePTFE fibers also have a height (thickness) (pre- or
post- weaving) less than about 200 microns. In some embodiments,
the thickness ranges from about 20 microns to about 150 microns,
from 20 microns to about 100 microns, from about 20 microns to
about 70 microns, from about 20 microns to 50 microns, from about
20 microns to 40 microns, or from about 26 microns to 36 microns.
The ePTFE fibers may have a pre- or post- weaving height
(thickness) less than 100 microns, less than 75 microns, less than
50 microns, less then 40 microns, less then 30 microns, or less
than 20 microns. The fibers also have a width (pre- or post-
weaving) less than about 4.0 mm. In at least one exemplary
embodiment, the fibers have a pre- or post- weaving width from
about 0.5 mm to about 4.0 mm, from about 0.40 mm to about 3.0 mm,
from about 0.45 mm to about 2.0 mm, or from about 0,45 mm to about
1.5 mm. The resulting aspect ratio (i.e., width to height ratio) of
the ePTFE fibers is greater than about 10. In some embodiments, the
aspect ratio is greater than about 15, greater than about 20,
greater than about 25, greater than about 30, greater than about
40, or greater than about 50. A high aspect ratio, such as is
achieved by the ePTFE fibers, enables low weight per area fabrics,
easier and more efficient reshaping, and can achieve high water
resistance in a woven fabric with less picks and ends per inch.
[0083] Further, the ePTFE fibers have a tenacity greater than about
1.4 cN/dtex. In at least one embodiment of the invention, the ePTFE
fibers have a tenacity from about 1.6 cN/dtex to about 5 cN/dtex,
from about 1.8 cN/dtex to about 4 cN/dtex, or from about 1.9
cN/dtex to about 3 cN/dtex. Additionally, the ePTFE fibers have a
fiber break strength of at least about 1.5 N. In one or more
embodiments, the ePTFE fibers have a fiber break strength from
about 2 N to about 20 N, from about 2 N to about 15 N, from about 2
N to about 10 N, or from about 2 N to about 5 N.
[0084] The ePTFE fibers described herein may be used to form a
woven fabric having warp and weft fibers interwoven with one
another in a repeating weave pattern. Any weave pattern, such as,
but not limited to, plain weaves, satin weaves, twill weaves, and
basket weaves, may be used to form the ePTFE fibers into a woven
fabric. The ePTFE fiber may be woven fiat without folds or creases
when the width of the ePTFE fiber is less than the allotted space
provided for the fiber based on the number of the picks per inch
and/or ends per inch. Such a fiber, when loosely woven, includes
visible gaps between the crossovers (intersections) of the warp and
weft fibers. As such, the fabric is highly breathable but is not
water resistant. Such large gaps in the fabric may be acceptable in
applications where, for example, the water resistance is to be
provided by another layer or in situations where general areal
coverage is desired and water resistance is not critical.
[0085] In other embodiments, the fiber is more tightly woven, such
as when the width of the ePTFE fiber exceeds the allotted space in
the woven fabric based on the number of picks per inch and/or ends
per inch. In such a fabric, there is no, or substantially no, gaps
between the crossovers. The width of the ePTFE fiber may be greater
than 1 times, greater than about 1.5 times, greater than about 2
times, greater than about 3 times, greater than about 4 times,
greater than about 4.5 times, greater than about 5 times, greater
than about 5.5 times, or greater than about 6 times (or more) the
space provided to the fibers based on the number of picks per inch
and/or ends per inch. In other words, the ePTFE fibers are woven
tighter than the width of the ePTFE fiber. In such embodiments, the
ePTFE fibers begin the weaving process in a substantially
rectangular configuration. however, due to the larger size of the
fiber compared to the space provided by the picks per inch and/or
ends per inch, the ePTFE fibers curl and/or fold upon themselves to
conform to the weave spacing determined by the number of picks per
inch and/or ends per inch of the warp and weft fibers. Generally,
the folding or curling occurs in the width of the fiber such that
the width of each individual fiber becomes smaller as the folding
or curling of the fiber occurs. The fibers are thus in a folded
configuration along a length of the fiber.
[0086] The conformability of the ePTFE fibers is schematically
depicted in FIGS. 40 and 41. In FIGS. 40 and 41, the fibers 10 are
to be positioned in space (S) in a woven fabric. As shown in FIGS.
40 and 41, the widths (W) of the fibers 10 are larger than the
space (S) allotted for the fibers 10 in the woven fabric. In order
to fit into the space (S) allotted for the fibers 10, the fibers 10
fold or curl into a folded configuration 15, such as is illustrated
in FIG. 40.
[0087] The "foldability" or "folded configuration" of the ePTFE
fibers is evidenced by a line 20 extending along the length of the
fibers, as is shown in at least FIGS. 3, 5, 7, 10, 13, 16, 18, 20,
24, 26, 30, and 38. FIGS. 44 and 45, which are cross-section SEMs
of an exemplary woven fabric, illustrate the conformability of the
ePTFE fibers, as these figures clearly depict the folding (and/or
curling) of the fiber upon itself. FIG. 41 depicts a top schematic
view of the fibers in a curled configuration. The fibers may fold
upon themselves in the warp and/or the weft direction. As shown in
FIG. 41, the fibers conform to fit into space (S). In a fabric
including warp and weft fibers, at least one of the warp and weft
fibers is in a folded configuration along, or substantially along,
a length of the fiber. Thus, the ePTFE fibers fold and/or curl to a
smaller width in the woven fabric. As one prophetic example, in a
88 ppi.times.88 epi woven fabric and an ePTFE fiber width of 1 mm,
the ePTFE fiber will fold upon itself to produce a folded width 3.5
times less than its original width in order to accommodate the
space provided in the weave configuration (e.g. 88 ppi divided by
25.4 mm/1 inch is 3.5 picks per mm).
[0088] The conformability of the ePTFE fiber allows larger sized
ePTFE fibers to be utilized in smaller weave spacing. Increasing
the number of picks per inch and/or ends per inch compared to the
width of the fiber reduces or even eliminates gaps between where
the warp and weft fibers intersect. Such tightly woven fabrics are
concurrently highly breathable and water resistant (e.g., have a
high water entry pressure). It is to be appreciated that the fabric
breathes not only through whatever gap may be present but also
through the ePTFE fiber itself. Even when there are no gaps
present, the woven fabric remains breathable. In contrast,
conventional woven fabrics, when tightly woven, become
non-breathable.
[0089] Not wishing to be bound by theory, it is believed that the
conformability of the ePTFE fiber as well as the node and fibril
structure enables the woven fabric to achieve many, if not all, of
the features and advantages described herein. For example, the
nodes of the ePTFE fiber help the fiber to maintain an "open"
configuration of the fibrils when the fiber is woven. The open
pores of the ePTFE fibers greatly enhance the breathability of the
woven fabric. The fineness of the pores prevents water into the
fiber structure while maintaining high breathability. As discussed
previously, the conformability of the ePTFE fibers permits for the
fibers to be woven in a tight configuration to render the woven
fabric water resistant yet breathable.
[0090] Treatments may be provided to impart one or more desired
functionality, such as, but not limited to, oleophobicity to the
woven fabric. When provided with an oleophobic coating, such as,
but not limited to, a fluoroacrylate olephobic coating, the woven
fabric has an oil rating greater than or equal to 1, greater than
or equal to 2, greater than or equal to 3, greater than or equal to
4, greater than or equal to 5, or greater than or equal to 6 when
tested according to the Oil Rating Test described herein. Coatings
or treatments, such as a fluoroacrylate coating, may be applied to
one or both sides of the woven fabric, and may penetrate through or
only partially through the woven fabric. It is to be understood
that any functional protective layer, functional coating, or
functional membrane, such as, but not limited to, polyamides,
polyesters, polyurethanes, cellophane, non-fluoropolymer membranes
that are both waterproof and breathable may be attached or
otherwise affixed or layered on the woven fabric.
[0091] The woven fabric may be colored by a suitable colorant
composition. The ePTFE fiber has a microstructure where the pores
of the ePTFE fiber are sufficiently tight so as to provide water
resistance and sufficiently open to provide properties such as
moisture vapor transmission and penetration by coatings of
colorants. The ePTFE fiber has a surface that, when printed,
provides a durable aesthetic. Aesthetic durability can be achieved
in some embodiments with colorant coating compositions that
comprise a pigment having a particle size that is sufficiently
small to fit within the pores of the ePTFE fiber and/or within the
woven fabric. Multiple colors may be applied using multiple
pigments, by varying the concentrations of one or more pigments, or
by a combination of these techniques. Additionally, the coating
composition may be applied in any form, such as a solid, pattern,
or print. A coating composition can be applied to the woven fabric
by conventional printing methods. Application methods for
colorizing include but are not limited to, transfer coating, screen
printing, gravure printing, ink-jet printing, and knife
coating.
[0092] Unlike conventional woven fabrics, the ePTFE woven fabric is
able to breathe through the fibers forming the fabric (i.e., the
ePTFE fibers) as well as through the gaps formed between the ePTFE
fibers during weaving. As discussed above, the ePTFE fibers have a
node and fibril construction that forms passageways through the
fibers that make the ePTFE fiber breathable. When the ePTFE fiber
is woven, the node and fibril structure maintain open passageways.
Thus, even when the ePTFE fiber is tightly woven such that there
are no gaps or substantially no gaps formed in the woven structure,
the ePTFE woven fabric maintains its high breathability. The ePTFE
woven fabrics have a moisture vapor transmission rate (MVTR) that
is greater than about 3000 g/m.sup.2/24 hours, greater than about
5000 g/m.sup.2/24 hours, greater than about 8000 g/m.sup.2/24
hours, greater than about 10000 g/m.sup.2/24 hours, greater than
about 12000 g/m.sup.2/24 hours, greater than about
15000g/m.sup.2/24 hours, greater than about 20000 g/m.sup.2/24
hours, or greater than about 25000 g/m.sup.2/24 hours when tested
according to the moisture vapor transmission rate (MVTR) Test
Method described herein. As used herein, the term "breathable" or
"breathability" refers to woven fabrics or laminates that have a
moisture vapor transmission rate (MVTR) of at least about 3000
grams/m.sup.2/24 hours. Moisture vapor transmission, or
breathability, provides cooling to a wearer of a garment, for
example, made from the woven fabric.
[0093] The woven fabrics also have an air permeability that is less
than about 500 cfm, less than about 300 cfm, less than 100 cfm,
less than about 50 cfm, less than about 25 cfm, less than about 20
cfm, less than about 15 cfm, less than about 10 cfm, less than
about 5 cfm, less than about 3 cfm, and even less than about 2 cfm.
It is to be understood that low air permeability correlates to
improved windproofness of the fabric.
[0094] ePTFE woven fabrics described herein have a water pick-up
less than or equal to about 50 g/m.sup.2, less than or equal to 40
g/m.sup.2, less than or equal to about 30 g/m.sup.2, less than or
equal to about 25 g/m.sup.2, less than or equal to about 20
g/m.sup.2, less than or equal to about 15 g/m.sup.2, or less than
or equal to about 10 g/m.sup.2 and a water entry pressure of at
least about 1 kPa, at least about 1.5 kPa, at least about 2 kPa, at
least about 3 kPa, at least about 4 kPa, at least about 5 kPa, or
at least about 6 kPa. The ePTFE fibers restrict the entry of water
into the woven fabric (into, e.g., the fiber structure and through
the gaps of the woven fabric), thus eliminating problems associated
with conventional woven fabrics that absorb water, which, in turn,
makes the fabrics heavier, and permits for thermal conductivity of
the temperature of the water through the fabric. Such thermal
conductivity may be detrimental in cases where the wearer is in a
cold environment and the cold is transported to the body of the
wearer.
[0095] Additionally, the woven fabrics are thin and lightweight,
which permits the end user to easily carry and/or transport
articles formed from the woven fabrics. The woven fabrics may have
a weight from about 50 g/m.sup.2 to about 500 g/m.sup.2, from about
80 g/m.sup.2 to about 300 g/m.sup.2, or from about 90 g/m.sup.2 to
about 250 g/m.sup.2. Additionally, the woven fabrics may have a
weight per unit area of less than about 1000 g/m.sup.2, less than
about 500 g/m.sup.2, less than about 400 g/m.sup.2, less than about
300 g/m.sup.2, less than about 200 g/m.sup.2, less than about 150
g/m.sup.2, or less than about 100 g/m.sup.2. Further, the woven
fabrics may have a height (thickness) from about 0.05 mm to about 2
mm, from about 0.1 mm to about 1 mm, from about 0.1 mm to about 0.6
mm, from about 0.1 mm to about 0.5 mm, from about 0.1 mm to about
0.4 mm, from about 0.15 mm to about 0.25 mm, or from about 0.1 mm
to about 0.3 mm. The thinness of the woven fabric enables articles
formed from the woven fabric to be folded compactly. The thin and
light weight features also contributes to the overall comfort of
the wearer of the garment, especially during movement of the wearer
as the wearer experiences less restriction to movement.
[0096] Further, the woven fabrics have a soft hand and are
drapable, making them suitable for use in garments, gloves, and
footwear. The woven fabric has an average stiffness less than about
1000 g, less than about 500 g, less than about 400 g, less than
about 300 g, less than about 250 g, less than about 200 g, less
than about 150 g, less than about 100 g, and even less than about
50 g. It was surprisingly discovered that in addition to a soft
hand, the woven fabrics demonstrated a reduction in noise
associated with bending or folding the woven fabric. It was further
discovered that even with the addition of a porous polymer
membrane, as discussed hereafter, the noise was reduced,
particularly when compared to conventional ePTFE laminates.
[0097] The woven fabrics are also resistant to tearing. For
example, the woven fabric has a tear strength from about 10 N to
about 200 N (or even greater), from about 15 N to about 150 N, or
from about 20 N to about 100 N as measured by the Elemendorf Tear
test described herein. Such a high tear strength enables the woven
fabric to be more durable in use.
[0098] In at least one embodiment, a porous or microporous polymer
membrane is laminated or bonded to the woven fabric. Non-limiting
examples of porous membranes including expanded PTFE, expanded
modified PTFE, expanded copolymers of PTFE, fluorinated ethylene
propylene (FEP), and perfluoroalkoxy copolymer resin (PFA).
Polymeric materials such as polyolefins (e.g., polypropylene and
polyethylene), polyurethanes, and polyesters are considered to be
within the purview of the invention provided that the polymeric
material can be processed to form porous or microporous membrane
structures. It is to be appreciated that even when the inventive
woven fabric is laminated or bonded to a porous or microporous
membrane, the resulting laminate remains highly breathable and
substantially maintains the breathability of the woven fabric. In
other words, the porous or microporous membrane laminated to the
woven fabric does not affect, or only minimally affects, the
breathability of the woven fabric, even when laminated.
[0099] The microporous membrane may be an asymmetric membrane. As
used herein, "asymmetric" is meant to indicate that the membrane
structure includes multiple layers of ePTFE within the membrane
where at least one layer within the membrane has a microstructure
that is different from the microstructure of a second layer within
the membrane. The difference between the first microstructure and
the second microstructure may be caused by, for example, a
difference in pore size, a difference in node and/or fibril
geometry or size, and/or a difference in density.
[0100] In a further embodiment, a textile may be attached to the
microporous membrane or directly to the woven fabric. As used
herein, the term "textile" is meant to denote any woven, nonwoven,
felt, fleece, or knit and can be composed of natural and/or
synthetic fiber materials and/or other fibers or flocking
materials. For example, the textile may be comprised of materials
such as, but not limited to cotton, rayon, nylon, polyester, and
blends thereof. The weight of the material forming the textile is
not particularly limited except as required by the application. In
exemplary embodiments, the textile is air permeable and
breathable.
[0101] Any suitable process for joining the membrane and/or the
textile to the woven fabric (and textile to the membrane) may be
used, such as gravure lamination, fusion bonding, spray adhesive
bonding, and the like. The adhesive may be applied discontinuously
or continuously, provided that breathability through the laminate
is maintained. For example, the adhesive may be applied in the form
of discontinuous attachments, such as by discrete dots or grid
pattern, or in the form of an adhesive web to adhere layers of the
laminate together.
[0102] The ePTFE woven fabric is suitable for use in various
applications, including but not limited to garments, tents, covers,
bivy bags, footwear, gloves, and the like. The woven fabric is
concurrently highly breathable and water resistant. These
advantageous features are achieved, at least in part, due to the
high aspect ratio of the ePTFE fiber. The ePTFE woven fabric can be
used alone, or it can be used in conjunction with a fluoropolymer
membrane and/or textile. The surface of the ePTFE woven fabric can
be colorized, for example, by printing. Additionally, the surface
of the ePTFE fabric and/or the ePTFE fiber can be coated with an
oleophobic coating composition to provide oleophobicity. It should
be appreciated that the benefits and advantages described herein
equally apply to knitted fabrics and articles as well as the woven
fabrics and articles discussed herein.
TEST METHODS
[0103] It should be understood that although certain methods and
equipment are described below, any method or equipment determined
suitable by one of ordinary skill in the art may be alternatively
utilized.
Fiber Weight per Length
[0104] A 45 meter length of fiber was obtained using a skein reel.
The 45 meter length was then weighed on a scale with precision to
0.0001 grams. This weight was then multiplied by 200 to give the
weight per length in terms of denier (g/9000 m). This value was
then multiplied by 10 and divided by 9 to give the weight per
length in terms of dtex (g/10,000 m).
Fiber Width
[0105] Fiber width was measured in a conventional manner utilizing
a 10.times.eye loop having gradations to the nearest 0.1 mm. Three
measurements were taken and averaged to determine the width to the
nearest 0.05 mm.
Fiber Thickness
[0106] Fiber thickness was measured utilizing a snap gauge accurate
to the nearest 0.0001 inch. Care was taken to not to compress the
fibers with the snap gauge. Three measurements were taken and
averaged and then converted to the nearest 0.0001 mm.
Fiber Density
[0107] Fiber density was calculated utilizing the previously
measured fiber weight per length, fiber width and fiber thickness
using the following formula:
Fiber Density ( g / cm 3 ) = Fiber wt per length ( dtex ) Fiber
Width ( mm ) * Fiber Thickness ( mm ) * 10 , 000 ##EQU00001##
Fiber Break Strength
[0108] The fiber break strength was the measurement of the maximum
load needed to break (rupture) the fiber. The break strength was
measured by a tensile tester, such as an Instron.RTM. Machine of
Canton, Mass. The Instron.RTM. machine was outfitted with fiber
(horn type) jaws that are suitable for securing fibers and strand
goods during the measurement of tensile loading. The cross-head
speed of the tensile tester was 25.4 cm per minute. The gauge
length was 25.4 cm. Five measurements of each fiber type were taken
with the average reported in units of Newtons.
Fiber Tenacity
[0109] Fiber tenacity is the break strength of the fiber normalized
to the weight per length of the fiber. Fiber tenacity was
calculated using the following formula:
Fiber tenacity ( cN / dtex ) = Fiber break strength ( N ) * 100
Fiber weight per length ( dtex ) ##EQU00002##
Fabric and Membrane Thickness
[0110] The fabric and membrane thicknesses were measured by placing
either the membrane or textile laminate between the two plates of a
Mitutoyo 543-252BS Snap Gauge. The average of the three
measurements was used. It is to be appreciated that the thickness
of the fabric and/or the membrane may be determined by any suitable
method as determined by one of skill in the art.
Matrix Tensile Strength (MTS) of Membrane
[0111] Matrix Tensile Strength of the membrane was measured using
an Instro.RTM. 1122 tensile test machine equipped with flat-faced
grips and a 0.445 kN load cell. The gauge length was 5.08 cm and
the cross-head speed was 50.8 cm/min. The sample dimensions were
2.54 cm by 15.24 cm. To ensure comparable results, the laboratory
temperature was maintained between 68.degree. F. (20.degree. C.)
and 72.degree. F. (22.2.degree. C.) to ensure comparable results.
Data was discarded if the sample broke at the grip interface.
[0112] For longitudinal MTS measurements, the larger dimension of
the sample was oriented in the machine, or "down web," direction.
For the transverse MTS measurements, the larger dimension of the
sample was oriented perpendicular to the machine direction, also
known as the "cross web" direction. Each sample was weighed using a
Mettler Toledo Scale Model AG204. The thickness of the samples was
then measured using a Kafer FZ1000/30 snap gauge. The samples were
then tested individually on the tensile tester. Three different
sections of each sample were measured. The average of the three
maximum load (i.e., the peak force) measurements was used.
[0113] The longitudinal and transverse MTS were calculated using
the following equation:
MTS=(maximum load/cross-section area)*(bulk density of
PTFE)/density of the porous membrane),
where the bulk density of PTFE is taken to be 2.2 g/cm.sup.3.
[0114] The average of three cross-web measurements was recorded as
the longitudinal and transverse MTS.
Density of Membrane
[0115] To calculate the density of the membrane, measurements from
the Matrix Tensile Testing were used. As mentioned above, the
sample dimensions were 2.54 cm by 15.24 cm. Each sample was weighed
using a Mettler Toledo Scale Model AG204 and then the thickness of
the samples was taken using a Kafer FZ1000/30 snap gauge. Using
this data, a density of the sample can be calculated with the
following formula:
.rho. = m w * l * t ##EQU00003## [0116] where: .rho.=density
(g/cm.sup.3) [0117] m=mass (g) [0118] w=width (1.5 cm) [0119]
l=length (16.5 cm) [0120] t=thickness (cm)
[0121] The reported results are the average of three
calculations.
Gurley Air Flow of Membrane
[0122] The Gurley air flow test measures the time in seconds for
100 cm.sup.3 of air to flow through a 6.45 cm.sup.2 sample at 12.4
cm of water pressure. The samples were measured in a Gurley
Densometer Model 4340 Automatic Densometer. When multiple tests are
performed on the same sample, care must be taken to ensure that the
edges of the test areas do not overlap. (The compression that
occurs to the material along the edges of the test area when it is
clamped to create a seal during a Gurley test can affect the air
flow results.) The reported results are the average of three
measurements.
Moisture Vapor Transmission Rate Test--(MVTR)
[0123] The MVTR for each sample fabric was determined in accordance
with the general teachings of ISO 15496 except that the sample
water vapor transmission (WVP) was converted into MVTR moisture
vapor transmission rate (MVTR) based on the apparatus water vapor
transmission (WVPapp) and using the following conversion.
MVTR=(Delta P value*24)/((1/WVP)+(1+WVPapp value))
[0124] To ensure comparable results, the specimens were conditioned
at 73.4.+-.0.4.degree. F. and 50.+-.2% rH for 2 hrs prior to
testing and the bath water was a constant 73.4.degree.
F..+-.0.4.degree. F.
[0125] The MVTR for each sample was measured once, and the results
are reported as g/m.sup.2 /24 hours.
Mass/Area
[0126] In order to measure mass per area, fabric samples were
prepared having an area of at least 100 cm.sup.2. A Karl Schroder
100 cm.sup.2 circle cutter may be used. Each sample was weighed
using a Mettler Toledo Scale Model AB204. The scale was
recalibrated prior to weighing specimens, and the results were
reported in grams per square meter (gsm). For membrane samples, the
reported results are the average of three measurements. For printed
laminate samples, the reported data is the result of a single
measurement.
Oil Rating Test
[0127] Oil rating of both membranes and laminates were measured.
Tests were conducted following the general teachings of AATCC Test
Method 118-1997. The oil rating number is the highest number oil
which does not wet the material within a test exposure time of
30.+-.2 seconds. The reported results are the average of three
measurements.
SEM Sample Preparation Method
[0128] Cross-section SEM samples were prepared by spraying them
with liquid nitrogen and then cutting the sprayed samples with a
diamond knife in a Leica ultracut UCT, available from Leica
Microsystems, Wetzlar, Germany.
Fibril Length Measurement
[0129] The surface SEM images were used to measure fibril length. A
magnification was chosen to enable the viewing of multiple fibrils,
including a clear view of the points where fibrils attached to
nodes. The same magnification was used for each sample that was
measured. Since these node and fibril structures were irregular, 15
different fibrils, randomly distributed across each image, were
identified for measurement.
[0130] To measure each fibril accurately, lines were drawn with the
cursor so that they were perpendicular to the fibril on both ends
where the fibril attaches to the node. The distance between the
cursor drawn lines were measured, and recorded for each fibril. The
results for each surface image of each sample were averaged. The
reported value for fibril length represents the average of 15
sample measurements on the SEM image.
Liquidproof Test (Suter) and Water Pick-Up
[0131] Liquidproof testing and water pick-up was conducted as
follows. Laminates were tested for liquidproofness by using a
modified Suter test apparatus with water serving as a
representative test liquid. Water is forced against a sample area
of about 4 1/4 inch (10.8 cm) diameter sealed by two rubber gaskets
in a clamped arrangement. Samples are tested by orienting the
sample so that the outer film surface of the sample is the surface
against which water is forced. The water pressure on the sample is
increased to about 0.7 psi (6.94.81 KPa) by a pump connected to a
water reservoir, as indicated by an appropriate gauge and regulated
by an in-line valve. The test sample was positioned at an angle,
and the water was recirculated to ensure that water, not air,
contacted the lower surface of the sample. The surface opposite the
outer film surface of the sample was observed for a period of 3
minutes for the appearance of any water which would be forced
through the sample. Liquid water seen on the surface was
interpreted as a leak.
[0132] A passing (liquidproof) grade was given in cases where no
liquid water is visible on the sample surface within 3 minutes. A
sample was deemed "liquidproof" as used herein if it passed this
test. Samples having any visible liquid water leakage, e.g. in the
form of weeping, pin hole leak, etc. were not considered
liquidproof and failed the test.
[0133] To determine water pick up the sample was weighed before and
after the test. The difference in grams was converted to grams per
square meter from a 10.8 cm diameter circle sample, thereby
providing the weight increase picked up from water. The reported
results are the average of three measurements.
Gap Between Fibers Measurement
[0134] Surface SEM images were used to measure the gap between
fibers. A magnification was chosen to enable the viewing of at
least ten fiber crossovers, including a clear view of the gaps
where the fibers overlap. For each gap, the distance (D) between
the fibers, at the crossovers 30 as shown in FIG. 52, was measured
to the nearest micrometer in the warp direction. This distance (D)
was measured and averaged for at least ten crossovers within the
field of view. It is to be noted that only two crossovers 30 are
depicted in FIG. 52, and are for purposes of illustration only.
Also, for each gap, the distance (D') orthogonal to the direction
corresponding to distance between the fibers at the crossovers 30
was measured to the nearest micrometer in the fill direction. This
distance D' was measured and averaged for at least ten crossovers
within the field of view. The average gap distance (D) in the warp
direction and the average gap distance (D') in the fill direction
were reported, with the larger value reported first.
Water Entry Pressure (WEP)
[0135] Water entry pressure provides a test method for water
intrusion through membranes and/or fabrics. A test sample is
clamped between a pair of testing plates. The lower plate has the
ability to pressurize a section of the sample with water. A piece
of pH paper is placed on top of the sample between the plate on the
non-pressurized side as an indicator of evidence for water entry.
The sample is then pressurized in small increments, waiting 10
seconds after each pressure change until a color change in the pH
paper indicates the first sign of water entry. The water pressure
at breakthrough or entry is recorded as the Water Entry Pressure.
The test results are taken from the center of test sample to avoid
erroneous results that may occur from damaged edges.
Tear Strength
[0136] This test is designed to determine the average force
required to propagate a single-rip tongue-type tear starting from a
cut in woven fabric. A Thwing-Albert Heavy Duty Elmendorf Tearing
Tester (MAI227) was used. After the instrument was calibrated and
the correct pendulum weight was selected, a blinking asterisk on
the left side of the display will indicate the instrument is ready
for testing. The pendulum was raised to the starting position. The
specimen was placed in jaws and clamped using the air clamp located
on the lower right side of instrument. The air pressure was between
414 KPa and 621 KPa. The specimen was centered with the bottom edge
carefully against the stops. The upper area of the specimen should
be directed towards the pendulum to ensure a shearing action. The
test was performed until a complete tear was achieved. The digital
readout was recorded in Newtons. This was repeated until a set (1
warp and 1 weft). The reported results are the average of the
measurements for one set.
Stiffness
[0137] A Thwing Albert Handle-O-Meter with a 1000 g beam and 1/4''
slot width was used to measure the hand (stiffness). A
4''.times.4'' sample was cut from the fabric. The specimen was
placed face up on the specimen platform. The specimen was lined up
so that the test direction is perpendicular to the slot to test the
warp direction. The START/Test button was pressed until a click is
heard, then released. The number appearing on the digital display
after a second click is heard was recorded. The reading will not
return to zero but will show the peak reading of each individual
test. The specimen was turned over and tested again, recording the
number. Then the specimen was turned 90 degrees to test the fill
direction, recording the number. Finally, the specimen was turned
over and tested again, recording the number. The 4 recorded numbers
were added together (1 Warp Face, 1 Warp Back, 1 Fill face, 1 Fill
Back) to calculate the overall stiffness of the specimen in grams.
The results were reported for one sample.
Air Permeability-Frazier Number Method
[0138] Air permeability was measured by clamping a test sample in a
gasketed flanged fixture which provided a circular area of
approximately 6 square inches (2.75 inches diameter) for air flow
measurement. The upstream side of the sample fixture was connected
to a flow meter in line with a source of dry compressed air. The
downstream side of the sample fixture was open to the
atmosphere.
[0139] Testing was accomplished by applying a pressure of 0.5
inches of water to the upstream side of the sample and recording
the flow rate of the air passing through the in-line flowmeter (a
ball-float rotameter).
[0140] The sample was conditioned at 70.degree. F. (21.1.degree.
C.) and 65% relative humidity for at least 4 hours prior to
testing.
[0141] Results are reported in terms of Frazier Number which is air
flow in cubic feet/minute/square foot of sample at 0.5 inches water
pressure.
EXAMPLES
Example 1a
[0142] A fine powder PTFE resin (Teflon 669 X, commercially
available from E. I. du Pont de Nemours, Inc., Wilmington, Del.)
was obtained. The resin was blended with Isopar.RTM. K in the ratio
of 0.184 g/g by weight of powder. The lubricated powder was
compressed in a cylinder and allowed to dwell at room temperature
for 18 hours. The pellet was then ram extruded at a 169 to one
reduction ratio to produce a tape of approximately 0.64 mm thick.
The extruded tape was subsequently compressed to a thickness of
0.25 mm. The compressed tape was then stretched in the longitudinal
direction between two banks of rolls. The speed ratio between the
second bank of rolls and the first bank of rolls, hence the stretch
ratio was 1.4:1 with a stretch rate of 30%/sec. The stretched tape
was then restrained and dried at 200.degree. C. The dry tape was
then expanded between banks of heated rolls in a heated chamber at
a temperature of 300.degree. C. to a ratio of 1.02:1 at a stretch
rate of 0.2%/sec, followed by an additional expansion ratio of
1.75:1 at a stretch rate of 46%/sec, followed by an additional
expansion ratio of 1.02:1 at a stretch rate of 0.5%/sec. This
process produced a tape with a thickness of 0.24 mm.
[0143] This tape was then slit to create a cross-section of 1.78 mm
wide by 0.24 mm thick and having a weight per length of 3494 dtex.
The slit tape was then expanded over a heated plate set to
390.degree. C. at a stretch ratio of 6.25:1 with a stretch rate of
65%/sec. This was followed by further expansion across a heated
plate set to 390.degree. C. at a stretch ratio of 2.50:1 with a
stretch rate of 66%/sec. This was followed by a further expansion
across a heated plate set to 390.degree. C. at a stretch ratio of
1.30:1 with a stretch rate of 23%/sec. This was followed by running
across a heated plate set to 390.degree. C. at a stretch ratio of
1.00:1 for a duration of 1.6 seconds, resulting in an amorphously
locked expanded PTFE fiber.
[0144] The final amorphously locked ePTFE fiber measured 172 dtex
and had a rectangular cross-section and possessed the following
properties: width=1.0 mm, height=0.0356 mm, density=0.48
g/cm.sup.3, break strength of 3.51 N, tenacity of 2.04 cN/dtex, and
fibril length=53.7 microns.
[0145] A scanning electron micrograph (SEM) of a side of the
resulting fiber taken at 1000.times. magnification is shown in FIG.
1. FIG. 2 is a scanning electron micrograph of the top surface of
the fiber taken at 1000.times. magnification.
[0146] The fiber was then used to create a woven fabric. The
weaving pattern was 2/2 twill using a thread count of 88.times.88
threads/inch. The woven fabric had the following properties:
thickness=0.20 mm, MVTR=27860 g/m.sup.2/24 hours, water pick-up=13
gsm, hand=71 g, tear strength=75.6 N, WEP=5.38 kPa, air
permeability=0.81 cfm, and oil rating=<1. A scanning electron
micrograph of the surface of the fabric taken at 150.times.
magnification is depicted in FIG. 3. A scanning electron micrograph
of a side view of the fabric taken at 150.times. magnification is
shown in FIG. 4. The length and width of the gaps between the warp
and weft fibers were less than 0.01 mm. The fabric had a weight of
135 g/m.sup.2.
[0147] A fiber (172 dtex) was removed from the woven fabric and
dimensional measurements were taken of its conformed state
post-weaving in order to demonstrate the conformability of the
fiber. The fiber was determined to have a post-weaving folded width
of 0.30 mm, a post-weaving folded height of 0.0699 mm, a
post-weaving aspect ratio of 4.3, and a post-weaving density of
0.82 g/cm.sup.3. The pre-woven width to the post-weaving folded
width ratio was 3.3 to 1.
Example 1b
[0148] A fluoroacrylate coating was applied to the woven fabric of
Example 1a in order to render it oleophobic while preserving the
porous and microporous structure.
[0149] The resulting oleophobic woven fabric had the following
properties: thickness=0.20 mm, MVTR=21206 g/m.sup.2/24 hours, water
pick-up=11 gsm, hand=131 g, tear strength=63.8 N, WEP=6.11 KPa, air
permeability=1.72 cfm, and oil rating=6. A scanning electron
micrograph of surface of the woven fabric taken at 150.times.
magnification is shown in FIG. 5. A scanning electron micrograph of
a side view of the fabric taken at 150.times. magnification is
shown in FIG. 6. The length and width of the gaps between the
fibers were less than 0.01 mm. The fabric had a weight of 158
g/m.sup.2.
Example 1c
[0150] An amorphously locked ePTFE membrane was obtained having the
following properties: thickness=0.04 mm, density=0.47 g/cc, matrix
tensile strength in the strongest direction=105.8 MPa, matrix
tensile strength in the direction orthogonal to the strongest
direction=49.9 MPa, Gurley=16.2 s, MVTR=64168 g/m.sup.2/24
hours.
[0151] The woven fabric of Example 1b was laminated to the ePTFE
membrane in the following manner. The fabric and the ePTFE membrane
were bonded together by applying a dot pattern of a melted
polyurethane adhesive to the membrane. While the polyurethane
adhesive dots were molten, the fabric was positioned on top of the
adhesive side of the membrane. This construct (article) was allowed
to cool.
[0152] The resulting article had the following properties:
thickness=0.22 mm, MVTR=12845 g/m.sup.2/24 hours, water pick-up=12
gsm, hand=196 g, tear strength=46.19 N, and oil rating=6. A
scanning electron micrograph of the top surface of the article
taken at 150.times. magnification is presented in FIG. 7. A side
view of the article taken at 100.times. magnification is shown in
FIG. 8. A side view of the article taken at 1000.times.
magnification is shown in FIG. 9. The length and width of the gaps
between the fibers were less than 0.01 mm. The fabric had a weight
of 192 g/m.sup.2.
Example 1d
[0153] The woven fabric of Example 1b was laminated to a plain
weave nylon textile (weight of 18 g/m.sup.2, 150 ends per inch, and
109 picks per inch, 17 dtex (5 filaments) in the following manner.
The fabric and the textile were bonded together by applying a dot
pattern of a melted polyurethane adhesive to the fabric. While the
polyurethane adhesive dots were molten, the textile was positioned
on top of the adhesive side of the fabric. This construct was
allowed to cool.
[0154] The resulting article had the following properties:
thickness=0.25 mm, MVTR=14407 g/m.sup.2/24 hours, water pick-up=54
gsm, hand=288 g, tear strength=43.18 N, WEP=5.72; KPa, air
permeability=0.86 cfm, and oil rating=6. A scanning electron
micrograph of the top surface of the article taken at 150.times.
magnification is presented in FIG. 10. A scanning electron
micrograph of a side view of the article taken at 100.times.
magnification is shown in FIG. 11. A scanning electron micrograph
of a side view of the article taken at 500.times. magnification is
shown in FIG. 12. The length and width of the gaps between the
fibers were less than 0.01 mm. The fabric had a weight of 192
g/m.sup.2.
Example 1e
[0155] A laminated article was constructed in the following manner.
The membrane and the textile as described in Example 1a were bonded
together by applying a dot pattern of a melted polyurethane
adhesive to the membrane. While the polyurethane adhesive dots were
molten, the textile was positioned on top of the adhesive side of
the fabric. This construct was allowed to cool. Next, the fabric
was bonded to the membrane by applying a dot pattern of a melted
polyurethane adhesive to the membrane. While the polyurethane
adhesive dots were molten, the fabric was positioned on top of the
membrane. This construct was allowed to cool.
[0156] The resulting article had the following properties:
thickness=0.26 mm, MVTR=8708 g/m.sup.2/24 hours, water pick-up=11
gsm, hand=526 g, tear strength=37.78 N, and oil rating=6. A
scanning electron micrograph of the top surface of the article
taken at 150.times. magnification is shown in FIG. 13. A scanning
electron micrograph of a side view of the article taken at
100.times. magnification is shown in FIG. 14. A scanning electron
micrograph of a side view of the article taken at 300.times.
magnification is shown in FIG. 15. The length and width of the gaps
between the fibers were less than 0.01 mm. The fabric had a weight
of 216 g/m.sup.2.
Example 2a
[0157] A woven fabric was constructed in the same manner as
described in Example 1a with the exception that the weave pattern
was a plain weave. The woven fabric had the following properties:
thickness=0.15 mm, MVTR=21336 g/m.sup.2/24 hours, water pick-up=4
gsm, hand=83 g, oil rating=<1, WEP=3.13 KPa, air
permeability=0.44 cfm, and tear strength=36.3 N. A scanning
electron micrograph of the top surface of the fabric taken at
150.times. magnification is shown in FIG. 16. A scanning electron
micrograph of a side view of the article taken at 250.times.
magnification is shown in FIG. 17. The length and width of the gaps
between the fibers were about 0.01 mm and 0.01 mm, respectively.
The fabric had a weight of 142 g/m.sup.2.
[0158] A fiber (172 dtex) was removed from the woven fabric and
dimensional measurements were taken of its conformed state
post-weaving in order to demonstrate the conformability of the
fiber. The fiber was determined to have a post-weaving folded width
of 0.25 mm, a post-weaving folded height of 0.0736 mm, a
post-weaving aspect ratio of 3.4, and a post-weaving density of
0.94 g/cm.sup.3. The pre-woven width to the post-weaving folded
width ratio was 4.0 to 1.
Example 2b
[0159] The woven fabric of Example 2a was rendered oleophobic in
the same manner as described in Example 1b.
[0160] The oleophobic woven fabric had the following properties:
thickness=0.16 mm, MVTR=13265 g/m.sup.2/24 hours, water pick-up=7
gsm, hand=141 g, tear strength=30.3 N, WEP=4.01 KPa, Air
permeability=0.49 cfm, and oil rating=6. A scanning electron
micrograph of the top surface of the fabric taken at 150.times.
magnification is presented in FIG. 18. A scanning electron
micrograph of a side view of the fabric taken at 250.times.
magnification is shown in FIG. 19. The length and width of the gaps
between the fibers were about 0.01 mm and 0.02 mm, respectively.
The fabric had a weight of 158 g/m.sup.2.
Example 2c
[0161] An oleophobic laminated article was constructed in the
following manner. The membrane and the textile were bonded together
by applying a dot pattern of a melted polyurethane adhesive to the
membrane. While the polyurethane adhesive dots were molten, the
textile was positioned on top of the adhesive side of the fabric.
This construct was allowed to cool. Next, the fabric was bonded to
the membrane by applying a dot pattern of a melted polyurethane
adhesive to the membrane. While the polyurethane adhesive dots were
molten, the fabric was positioned on top of the membrane. This
construct was allowed to cool.
[0162] The resulting article had the following properties:
thickness=0.24 mm, MVTR=8274 g/m.sup.2/24 hours, water pick-up=10
gsm, hand=465 g, tear strength=20.59 N, and oil rating=6. A
scanning electron micrograph of the top surface of the article
taken at 150.times. magnification is presented in FIG. 20. A
scanning electron micrograph of a side view of the article taken at
250.times. magnification is shown in FIG. 21. The length and width
of the gaps between the fibers were about 0.01 mm and 0.03 mm,
respectively. The fabric had a weight of 214 g/m.sup.2.
Example 3a
[0163] A tape was produced in the same manner as described in
Example 1a. This tape was then slit to create a cross-section of
1.14 mm wide by 0.24 mm thick and having a weight per length of
2184 dtex. The slit tape was then expanded across a heated plate
set to 390.degree. C. at a stretch ratio of 6.00:1 with a stretch
rate of 70%/sec. This was followed by expansion across a heated
plate set to 390 C. at a stretch ratio of 2.50:1 with a stretch
rate of 74%/sec. This was followed by a further expansion across a
heated plate set to 390.degree. C. at a stretch ratio of 1.30:1
with a stretch rate of 26%/sec. This was followed by running across
a heated plate set to 390.degree. C. at a stretch ratio of 1.00:1
for a duration of 1.4 seconds resulting in an amorphously locked
expanded PTFE fiber.
[0164] The amorphously locked ePTFE fiber measured 112 dtex and had
a rectangular cross-section and possessed the following properties:
width=0.7 mm, height=0.0356 mm, density=0.45 g/cm3, break strength
of 2.14 N, tenacity of 1.92 cN/dtex, and fibril length=57.2
microns.
[0165] A scanning electron micrograph of the fiber taken at
1000.times. magnification is shown in FIG. 22. A scanning electron
micrograph of a side view of the fiber taken at 1000.times.
magnification is shown in FIG. 23.
[0166] The fiber was used to create a woven fabric. The weaving
pattern was 2/2 twill and a thread count of 100.times.100
threads/inch. The woven fabric had the following properties:
thickness=0.15 mm, MVTR=32012 g/m.sup.2/24 hours, water pick-up=21
gsm, hand=47 g, oil rating=<1, WEP=2.15 KPa, air
permeability=1.17 cfm, and tear strength=57.8 N. A scanning
electron micrograph of the woven fabric taken at 150.times.
magnification is shown in FIG. 24. A scanning electron micrograph
of a side view of the fabric taken at 200.times. magnification is
shown in FIG. 25. The length and width of the gaps between the
fibers were less than 0.01 mm. The fabric had a weight of 102
g/m.sup.2.
[0167] A fiber (112 dtex) was removed from the woven fabric and
dimensional measurements were taken of its conformed state
post-weaving in order to demonstrate the conformability of the
fiber. The fiber had a post-weaving folded width of 0.25 mm, a
post-weaving folded height of 0.0559 mm, a post-weaving aspect
ratio of 4.5, and a post-weaving density of 0.80 g/cm.sup.3. The
pre-woven width to the post-weaving folded width ratio was 2.8 to
1.
Example 3b
[0168] The woven fabric of Example 3a was rendered oleophobic in
the same manner as described in Example 1b. This article had the
following properties: thickness=0.15 mm, MVTR=20526 g/m.sup.2/24
hours, water pick-up=15 gsm, hand=86 g, tear strength=48.2 N,
WEP=5.45 KPa, air permeability=1.85 cfm, and oil rating=6. A
scanning electron micrograph of the fabric taken at 150.times.
magnification is shown in FIG. 26. A scanning electron micrograph
of a side view of the fabric taken at 200.times. magnification is
shown in FIG. 27. The length and width of the gaps between the
fibers were less than 0.01 mm. The fabric had a weight of 120
g/m.sup.2.
Example 4
[0169] A fine powder PTFE resin (Teflon 669 X, commercially
available from E. I. du Pont de Nemours, Inc., Wilmington, Del.)
was obtained. The resin was blended with Isopar(r) K in the ratio
of 0.184 g/g by weight of powder. The lubricated powder was
compressed in a cylinder and placed in an oven at a temperature of
49.degree. C. for 18 hours. The pellet was then ram extruded at a
169 to one reduction ratio to produce a tape of approximately 0.64
mm thick. The extruded tape was subsequently compressed to a
thickness of 0.25 mm. The compressed tape was then stretched in the
longitudinal direction between two banks of rolls. The speed ratio
between the second bank of rolls and the first bank of rolls, hence
the stretch ratio was 1.4:1 with a stretch rate of 30%/sec. The
stretched tape was then restrained and dried at 200.degree. C. The
dry tape was then expanded between banks of heated rolls in a
heated chamber at a temperature of 300.degree. C. to a ratio of
1.02:1 at a stretch rate of 0.2%/sec, followed by an additional
expansion ratio of 1.75:1 at a stretch rate of 46%/sec, followed by
an additional expansion ratio of 1.02:1 at a stretch rate of
0.5%/sec. This process produced a tape with a thickness of 0.24 mm
thick.
[0170] This tape was then slit to create a cross-section of 1.14 mm
wide by 0.24 mm thick and having a weight per length of 2373 dtex.
The slit tape was then expanded across a heated plate set to
390.degree. C. at a stretch ratio of 6.00:1 with a stretch rate of
69%/sec. This was followed by further expansion across a heated
plate set to 390.degree. C. at a stretch ratio of 2.20:1 with a
stretch rate of 32%/sec. This was followed by a further expansion
across a heated plate set to 390.degree. C. at a stretch ratio of
1.40:1 with a stretch rate of 19%/sec. This was followed by a
further expansion across a heated plate set to 390.degree. C. at a
stretch ratio of 1.20:1 with a stretch rate of 12%/sec. This was
followed by running across a heated plate set to 390.degree. C. at
a stretch ratio of 1.00:1 for a duration of 2.1 seconds, resulting
in an amorphously locked expanded PTFE fiber.
[0171] The final amorphously locked ePTFE fiber measured 107 dtex
and had a rectangular cross-section and possessed the following
properties: width=0.45 mm, height=0.0279 mm, density=0.85
g/cm.sup.3, break strength of 3.20 N, tenacity of 3.01 cN/dtex, and
fibril length=16.1 microns.
[0172] A scanning electron micrograph of the top surface of the
fiber taken at 1000.times. magnification is shown in FIG. 28. FIG.
29 is a scanning electron micrograph of a side view of the fiber
taken at 1000.times. magnification.
[0173] The fiber was used to create a woven fabric. The weaving
pattern was 2/2 twill and a thread count of 100.times.100
threads/inch. The woven fabric had the following properties:
thickness=0.13 mm, MVTR=28497 g/m.sup.2/24 hours, water pick-up=5
gsm, hand=72 g, oil rating=<1, WEP=1.96 KPa, Air
permeability=2.4 cfm, and tear strength=71.2 N. A scanning electron
micrograph of the top surface of the fabric taken at 150.times.
magnification is shown in FIG. 30. A side view of the fabric taken
at 150.times. magnification is shown in FIG. 31. The length and
width of the gaps between the fibers were less than 0.01 mm. The
fabric had a weight of 93 g/m.sup.2.
[0174] A fiber (107 dtex) was removed from the woven fabric and
dimensional measurements were taken of its conformed state
post-weaving in order to demonstrate the conformability of the
fiber. The fiber had a post-weaving folded width of 0.25 mm, a
post-weaving folded height of 0.0356 mm, a post-weaving aspect
ratio of 7.0, and a post-weaving density of 1.20 g/cm.sup.3. The
pre-woven width to the post-weaving folded width ratio was 1.8 to
1.
Example 5
[0175] A tape was produced in the same way as in Example 1a. This
tape was then slit to create a cross-section of 4.57 mm wide by
0.236 mm thick and having a weight per length of 7937 dtex. The
slit tape was then expanded across a heated plate set to
390.degree. C. at a stretch ratio of 6.00:1 with a stretch rate of
70%/sec. This was followed by another expansion across a heated
plate set to 390.degree. C. at a stretch ratio of 2.50:1 with a
stretch rate of 74%/sec. This was followed by a further expansion
across a heated plate set to 390.degree. C. at a stretch ratio of
1.30:1 with a stretch rate of 26%/sec. This was followed by running
across a heated plate set to 390.degree. C. at a stretch ratio of
1.00:1 for a duration of 1.4 seconds, resulting in an amorphously
locked expanded PTFE fiber.
[0176] The amorphously locked ePTFE fiber measured 452 dtex and had
a rectangular cross-section and possessed the following properties:
width=2.2 mm, height=0.0406 mm, density=0.51 g/cm3, break strength
of 11.48 N, tenacity of 2.55 cN/dtex, and fibril length=60 microns.
A scanning electron micrograph of the fiber surface taken at
1000.times. magnification is shown in FIG. 36. A scanning electron
micrograph of a side view of the fiber taken at 1000.times.
magnification is shown in FIG. 37.
[0177] The weaving pattern was a plain weave and had a thread count
of 50.times.50 threads/inch (19.7.times.19.7 threads/cm). The ratio
of the pre-woven fiber width to the calculated allotted space per
fiber within the weave pattern was 4.3 to 1. The woven fabric had
the following properties: thickness=0.24 mm, MVTR=14798
g/m.sup.2/24 hours, water pick-up=15 gsm, hand=281 g, oil
rating=<1, WEP=1.86 kPa, air permeability=2.1 cfm. A scanning
electron micrograph of the woven fabric taken at 150.times.
magnification is shown in FIG. 38. A scanning electron micrograph
of a side view of the fabric taken at 150.times. magnification is
shown in FIG. 39. The length and width of the gaps between the
fibers were about 0.04 mm and 0.01 mm, respectively. Scanning
electron micrographs of the top surface of the fabric taken at
120.times. magnification depicting the gap width measurements in
the horizontal direction and the gap width measurements in the
vertical direction are shown in FIGS. 40 and 41, respectively. The
fabric had a weight of 211 g/m.sup.2.
[0178] A fiber (452 dtex) was removed from the woven fabric and
dimensional measurements were taken of its conformed state
post-weaving in order to demonstrate the conformability of the
fiber. The fiber had a post-weaving folded width of 0.40 mm, a
post-weaving folded height of 0.1524 mm, a post-weaving aspect
ratio of 2.6, and a post-weaving density of 0.74 g/cm.sup.3. The
pre-woven width to the post-weaving folded width ratio was 5.5 to
1.
Example 6
[0179] A woven fabric was constructed in the same manner as
described in Example 5 with the exception that the plain weave
pattern had a thread count of 40.times.40 threads/inch
(15.7.times.15.7 threads/cm). The woven fabric had the following
properties: thickness=0.25 mm, MVTR=27846 g/m.sup.2/24 hours, water
pick-up=7 gsm, hand=71 g, oil rating=<1, WEP=1.69 KPa, and air
permeability=3.87 cfm. A scanning electron micrograph of the top
surface of the fabric taken at 150.times. magnification is shown in
FIG. 42. A scanning electron micrograph of a side view of the
fabric taken at 150.times. magnification is shown in FIG. 43.
Scanning electron micrographs of side views of the fabric taken at
300.times. and 400.times. magnifications are shown in FIGS. 44 and
45, respectively. FIG. 45 clearly depicts the conforming of the
fiber to the weave spacing, as the fiber has folded upon
itself.
[0180] The length and width of the gaps between the fibers were
about 0.08 mm and 0.02 mm, respectively. The fabric had a weight of
157 g/m.sup.2.
[0181] A fiber (452 dtex) was removed from the woven fabric and
dimensional measurements were taken of its conformed state
post-weaving in order to demonstrate the conformability of the
fiber. The fiber had a post-weaving folded width of 0.50 mm, a
post-weaving folded height of 0.1219 mm, a post-weaving aspect
ratio of 4.1, and a post-weaving density of 0.74 g/cm.sup.3. The
pre-woven width to the post-weaving folded width ratio was 4.4 to
1.
Comparative Example 1
[0182] An ePTFE fiber by W. L. Gore & Associates (part number
V111776, W. L. Gore & Associates, Inc., Elkton, Md.) was
obtained. The ePTFE fiber measured 111 dtex and had a rectangular
cross-section and possessed the following properties: width=0.5 mm,
height=0.0114 mm, density=1.94 g/cm.sup.3break strength=3.96 N,
tenacity=3.58 cN/dtex, and fibril length=indeterminate (no visible
nodes to define an endpoint for the fibrils). A scanning electron
micrograph of the top surface of the fiber taken at 1000.times.
magnification is shown in FIG. 32. A scanning electron micrograph
of a side view of the fiber taken at 1000.times. magnification is
shown in FIG. 33.
[0183] In order to successfully weave this fiber, it was twisted at
315 turns/meter. This twisted fiber was then woven into a fabric
using a 2/2 twill pattern and a thread count of 100.times.100
threads/inch.
[0184] The woven fabric had the following properties:
thickness=0.12 mm, MVTR=36756 g/m2/24 hours, water pick-up=4 gsm,
hand=102 g, WEP=0.39 kPa, air permeability=367 cfm, and oil
rating=<1. A scanning electron micrograph of the top surface of
the fabric taken at 150.times. magnification is shown in FIG. 34. A
scanning electron micrograph of a side view of the fabric taken at
150.times. magnification is shown in FIG. 35. The length and width
of the gaps between the fibers were about 0.09 mm and 0.12 mm,
respectively. The fabric had a weight of 94 g/m.sup.2.
Comparative Example 2
[0185] A non-microporous commercially available ePTFE fiber
available from W. L. Gore & Associates (part number V112961, W.
L. Gore & Associates, Inc., Elkton, Md.) was obtained. The
ePTFE fiber measured 457 dtex and had a rectangular cross-section
and possessed the following properties: width=0.6 mm, height=0.0419
mm, density=1.82 g/cm.sup.3, break strength=18.33 N, tenacity=4.03
cN/dtex, and fibril length=indeterminate (no visible nodes to
define an endpoint for the fibrils). A scanning electron micrograph
of the top surface of the fiber taken at 1000.times. magnification
is shown in FIG. 46. A scanning electron micrograph of a side view
of the fiber taken at 1000.times. magnification is shown in FIG.
47.
[0186] In order to successfully weave this ePTFE fiber, it was
twisted at 118 turns/meter. This twisted fiber was then woven into
a fabric using a plain weave pattern and a thread count of
50.times.50 threads/inch.
[0187] The woven fabric had the following properties:
thickness=0.21 mm, MVTR=11659 g/m.sup.2/24 hours, water pick-up=10
gsm, hand=380 g, WEP=0.49 kPa, air permeability=70 cfm, and oil
rating=<1. A scanning electron micrograph of the top surface of
the fabric taken at 150.times. magnification is shown in FIG. 48. A
scanning electron micrograph of a side view of the fabric taken at
150.times. magnification is shown in FIG. 49. The length and width
of the gaps between the fibers were about 0.11 mm and 0.08 mm,
respectively. The fabric had a weight of 201 g/m.sup.2.
Comparative Example 3
[0188] A commercially available ePTFE fiber available from W. L.
Gore & Associates (part number V112961, W. L. Gore &
Associates, Inc., Elkton, Md.) was obtained. The ePTFE fiber
measured 457 dtex and had a rectangular cross-section and possessed
the following properties: width=0.6 mm, height=0.0419 mm,
density=1.82 g/cm.sup.3, break strength=18.33 N, tenacity=4.03
cN/dtex, and fibril length=indeterminate (no visible nodes to
define an endpoint for the fibrils). A scanning electron micrograph
of the top surface of the fiber taken at 1000.times. magnification
is shown in FIG. 46. A side view of the fiber taken at 1000.times.
magnification is shown in FIG. 47.
[0189] In order to successfully weave this ePTFE fiber, it was
twisted at 138 turns/meter. This twisted fiber was then woven into
a fabric using a plain weave pattern and a thread count of
64.times.64 threads/inch.
[0190] The woven fabric had the following properties:
thickness=0.24 mm, MVTR=7840 g/m.sup.2/24 hours, water pick-up=9
gsm, hand=698 g, WEP=1.12 kPa, air permeability=26 cfm, and oil
rating=<1. A scanning electron micrograph of the top surface of
the fabric taken at 150.times. magnification is shown in FIG. 50. A
side view of the fabric taken at 150.times. magnification is shown
in FIG. 51. The length and width of the gaps between the fibers
were about 0.07 mm and 0.02 mm, respectively. The fabric had a
weight of 261 g/m.sup.2.
[0191] The invention of this application has been described above
both generically and with regard to specific embodiments. It will
be apparent to those skilled in the art that various modifications
and variations of the invention can be made without departing from
the spirit or scope of the invention, as defined in the appended
claims.
* * * * *