U.S. patent application number 08/962700 was filed with the patent office on 2001-08-30 for method and apparatus for controlled placement of a polymer composition into a web.
Invention is credited to CALDWELL, J. MICHAEL.
Application Number | 20010017102 08/962700 |
Document ID | / |
Family ID | 23611013 |
Filed Date | 2001-08-30 |
United States Patent
Application |
20010017102 |
Kind Code |
A1 |
CALDWELL, J. MICHAEL |
August 30, 2001 |
METHOD AND APPARATUS FOR CONTROLLED PLACEMENT OF A POLYMER
COMPOSITION INTO A WEB
Abstract
The present invention relates to an apparatus for controlling
the placement of a curable, shear-thinnable polymer composition
into a porous web. The apparatus comprises means for applying
tension, means for applying the polymer composition to one surface
of the tensioned web, and means for shear thinning the composition
and placing it into the web to encapsulate at least some of the
structural elements of the web, leaving most of the interstitial
spaces open. A preferred apparatus includes one or more process
heads that has mounted thereto a rigid knife blade for engagement
with the web. The knife blade is movable vertically and
rotationally. The process head is also movable horizontally along
the path of the web. The invention also relates to an apparatus for
selectively placing the polymer composition in a substantially
continuous region extending through the web so that the polymer
composition fills the interstitial spaces and adheres adjacent
structural elements of the web in the region. In the areas of the
web above and below the filled region, at least some of the
structural elements are encapsulated and most of the interstitial
spaces are open.
Inventors: |
CALDWELL, J. MICHAEL;
(CARDIFF, CA) |
Correspondence
Address: |
LYON & LYON LLP
SUITE 4700
633 WEST FIFTH STREET
LOS ANGELES
CA
90071-2066
US
|
Family ID: |
23611013 |
Appl. No.: |
08/962700 |
Filed: |
November 30, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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08962700 |
Nov 30, 1997 |
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08407191 |
Mar 17, 1995 |
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5876792 |
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08407191 |
Mar 17, 1995 |
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08017855 |
Feb 16, 1993 |
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5418051 |
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08017855 |
Feb 16, 1993 |
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07680645 |
Apr 2, 1991 |
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5209965 |
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07680645 |
Apr 2, 1991 |
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07319778 |
Mar 10, 1989 |
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5004643 |
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Current U.S.
Class: |
118/33 ; 156/229;
427/171 |
Current CPC
Class: |
D04H 1/64 20130101; B05C
11/04 20130101; D06M 15/564 20130101; D06B 15/08 20130101; D04H
1/43828 20200501; D04H 1/643 20130101; D04H 1/58 20130101; D04H
1/655 20130101; D04H 13/002 20130101; D04H 1/435 20130101; D06M
15/256 20130101; D06M 2200/12 20130101; C14C 9/00 20130101; D06M
15/657 20130101; Y10T 442/3813 20150401; D06M 15/643 20130101; D06M
2101/26 20130101; Y10T 442/659 20150401; C08J 2427/00 20130101;
D06M 2101/12 20130101; D04H 1/42 20130101; A61L 15/52 20130101;
D06N 3/0002 20130101; B05C 3/18 20130101; D21H 25/06 20130101; Y10S
977/891 20130101; C08J 2475/00 20130101; D06N 3/047 20130101; D06N
3/12 20130101; B05C 11/02 20130101; C14C 11/00 20130101; A61L 15/26
20130101; D06N 3/0025 20130101; C08J 2205/05 20130101; D04H 1/4266
20130101; D06M 2101/06 20130101; D06N 3/0029 20130101; D06N 3/128
20130101; D06M 2101/34 20130101; Y10T 428/249958 20150401; Y10T
428/249991 20150401; D06M 2101/32 20130101; Y10T 428/2495 20150115;
C08J 2433/00 20130101; C08J 2483/00 20130101; D06M 15/653 20130101;
D06M 15/263 20130101; D04H 1/425 20130101; D06M 15/3568 20130101;
D21H 17/59 20130101; D21H 19/32 20130101; Y10T 442/699 20150401;
A61L 15/26 20130101; C08L 83/04 20130101 |
Class at
Publication: |
118/33 ; 156/229;
427/171 |
International
Class: |
B05C 011/00; D06C
003/00; D06C 005/00; B21F 009/00 |
Claims
What is claimed is:
1. Apparatus for controlling the placement of a polymer composition
into a porous web having a plurality of structural elements with
interstitial spaces therebetween comprising: means for applying
tension to the porous web; means for applying a curable,
shear-thinnable, polymer composition onto a surface of the
tensioned web; and means for shear thinning the polymer composition
to substantially reduce its viscosity and selectively placing it
into the tensioned web, leaving at least some of the interstitial
spaces open.
2. Apparatus as set in forth in claim 1 wherein said polymer
composition is selectively placed to encapsulate at least some of
the structural elements of said web.
3. Apparatus as set forth in claim 1 wherein said polymer
composition is selectively placed as an internal layer within said
web positioned in a region extending through the web in a direction
generally spaced from at least one major surface of said web.
4. Apparatus as set forth in claim 1 wherein said polymer
composition is selectively placed to encapsulate at least some of
the structural elements of said web and to form an internal layer
within said web in a region extending through the web in a
direction generally spaced from at least one major surface of said
web.
5. Apparatus as set forth in claim 1 wherein the means for shear
thinning and placing comprises a blade urged against the surface of
the tensioned web downstream of the position where the polymer
composition is applied to the web.
6. Apparatus as set forth in claim 1 wherein the means for shear
thinning and placing comprises two or more blades spaced apart from
one another and urged against the surface of the tensioned web.
7. Apparatus as set forth in claim 6, including means for
controlling the spacing between said blades.
8. Apparatus as set forth in claim 5 wherein said blade is
positioned perpendicularly to said moving web.
9. Apparatus as set forth in claim 5, including means for varying
the angle of said blade relative to said web.
10. Apparatus as set forth in claim 5, including means for
controlling the force of said blade against said web.
11. Apparatus as set forth in claim 5 including means for advancing
the web past said blade.
12. Apparatus as set forth in claim 11, including means for varying
the exit angle of the moving web relative to said blade.
13. Apparatus as set forth in claim 11 including means for varying
the entrance angle of the moving web relative to said blade.
14. Apparatus as set forth in claim 11 including means for varying
both the entrance angle and the exit angle of said moving web
relative to said blade.
15. Apparatus as set forth in claim 6, including means for
advancing the web past said blades.
16. Apparatus as set forth in claim 15, including means for varying
the exit angle of the moving web relative to said blade.
17. Apparatus as set forth in claim 15, including means for varying
the entrance angle of the moving web relative to said blade.
18. Apparatus as set forth in claim 15, including means for varying
both the entrance angle and the exit angle of said moving web
relative to said blade.
19. Apparatus as set forth in claim 15, including means for
independently controlling the force of each of said blades against
said moving web.
20. Apparatus as set forth in claim 1, including means for
controlling the tension of the web.
21. Apparatus as set forth in claim 1, including means for scraping
the excess polymer from the surface of the web.
22. Apparatus as set forth in claim 1 including means for curing
the polymer composition within the porous web.
23. Apparatus as set forth in claim 22, including means for
controlling the temperature of the curing means.
24. Apparatus as set forth in claim 22, wherein said curing means
comprises a curing oven.
25. Apparatus as set forth in claim 5, including means for
controlling the temperature of said blade.
26. Apparatus as set forth in claim 6, including means for
controlling the temperature of each of said blades.
27. Apparatus as set forth in claim 5, including means for cooling
said blade to prevent premature cure of the polymer
composition.
28. Apparatus as set forth in claim 6, including means for cooling
said blades to prevent premature cure of said polymer
composition.
29. Apparatus as set forth in claim 11, wherein said advancing
means comprises a pair of counter-rotating nip rolls.
30. Apparatus as set forth in claim 29, including means for
controlling the pressure between said nip rolls.
31. Apparatus as set forth in claim 29, wherein one of the nip
rolls has a rubber surface of a predetermined hardness.
32. Apparatus as set forth in claim 29, wherein both nip rolls have
a rubber surface of predetermined hardness.
33. Apparatus as set forth in claim 5, including means for damping
the resonance of said blade.
34. Apparatus as set forth in claim 6, including means for damping
the resonance of said blades.
35. Apparatus as set forth in claim 5, including means for
vibrating said blade.
36. Apparatus as set forth in claim 5, including means for
vibrating said blade at a predetermined frequency.
37. Apparatus as set forth in claim 6, including means for
vibrating said blades.
38. Apparatus as set forth in claim 6, including means for
vibrating said blades individually at predetermined
frequencies.
39. Apparatus as set forth in claim 5, wherein said blade has a
flat surface at the bottom thereof.
40. Apparatus as set forth in claim 39, wherein the angle of entry
of the web into said blade is greater than 0 degrees and less than
90 degrees, the web follows the bottom surface of said blade and
the angle of exit of the web from said blade is greater than 0
degrees and less than 90 degrees.
41. Apparatus as set forth in claim 1, including means for applying
the polymer composition to the other side of said web, and means
for shear thinning and selectively placing the polymer composition
into said web from the other side of said web.
42. Apparatus as set forth in claim 22, including means for
controlling the release of longitudinal tension of said web to
cause the structural members to separate prior to cure.
43. Apparatus as set forth in claim 22 wherein said web is under
substantially no tension during curing.
44. Apparatus as set forth in claim 25 including means for holding
said web under transverse tension during curing.
45. Apparatus as set forth in claim 1 including means for
distorting the web during shear thinning to facilitate entrance of
the polymer composition within the web.
46. Apparatus as set forth in claim 45 wherein said means for
distorting comprises means for stretching said web
transversely.
47. Apparatus for controlled placement of a polymer composition
into a porous web comprising: means for advancing a web and
applying longitudinal tension; means for applying a polymer
composition of viscosity greater than 5,000 centipoise onto the
surface of said moving web; and means for shear thinning the
polymer composition and controlling the depth and placement of the
polymer composition within the web and for removing excess polymer
composition from the surface of the moving web.
48. Apparatus according to claim 47 wherein the means for shear
thinning and controlling comprises: a blade urged against the
advancing web; and means for controlling the force of the blade
against the web.
49. Apparatus according to claim 48 wherein the apparatus further
comprises one or more additional blades downstream from the first
blade for working the polymer composition into the web and removing
excess polymer composition from the surface of the web and from
within the web.
50. Apparatus for controlled placement of a polymer composition
into a porous web having a plurality of structural members
comprising: means for advancing a porous web; means for applying a
curable, shear-thinnable, polymer composition to one surface of the
web; means for shear thinning the polymer composition to
substantially reduce its viscosity and for placing the reduced
viscosity polymer composition into the porous web to form a thin
film coating on at least some of the structural members within the
web; means for controlling the longitudinal tension of the porous
web during shear thinning of said polymer composition into said
web; means for scraping the excess polymer composition from the
surface of the web; and means for curing the polymer composition
within the porous web.
51. Apparatus as set forth in claim 50 wherein longitudinal tension
on the web is substantially released immediately prior to and
during curing.
52. Apparatus as set forth in claim 50, including means for
controlling said shear thinning means to form an internal layer of
polymer within said web positioned in a region extending through
the web in a direction generally spaced from at least one major
surface of said web.
53. A method of controlled placement of a curable, shear-thinnable,
polymer composition into a porous web comprising: applying
longitudinal tension to the porous web; applying a polymer
composition onto a surface of the tensioned porous web; and shear
thinning the polymer composition sufficiently to reduce its
viscosity and selectively placing the viscosity reduced polymer
composition under pressure into the porous web.
54. The method of controlled placement according to claim 53
further comprising: distorting the porous web at the location of
the shear thinning to facilitate entrance of the polymer
composition into the web.
55. The method of controlled placement according to claim 54
wherein the distorting comprises stretching.
56. The method of controlled placement according to claim 55
wherein the stretching is by passage of the web under a roller
rotating against the web so as to move the web past a localized
area where the polymer composition is placed into the web.
57. The method of controlled placement according to claim 53
wherein the web is moved in one direction against a roller which
rotates in the opposite direction, and a polymer is applied between
the roller and the moving web.
58. The method of controlled placement according to claim 53
further comprising passing the treated web through a pair of nip
rolls under longitudinal tension and allowing the tension to be
released upon exiting the nip rolls to permit the fibers of the
porous web to separate from each other.
59. A method of controlled placement of a polymer composition into
a porous web comprising: shear thinning a polymer composition into
a porous web to reduce the viscosity of the polymer composition so
that the viscosity reduced polymer composition will be controllably
placed within the porous web; and distorting the porous web at a
location of the shear thinning to facilitate entrance of the
polymer composition into the web.
60. A method of controlled placement of a curable, shear-thinnable,
polymer composition into a porous web comprising: applying a
polymer composition onto a surface of the porous web; applying
longitudinal tension to said porous web; shear thinning the polymer
composition to substantially reduce its viscosity and placing the
shear thinned viscosity reduced polymer composition into the porous
web to encapsulate at least some of the fibers of the porous web
without substantially filling the interstitial spaces of the
web.
61. The method of controlled placement according to claim 60
further comprising: distorting the porous web at a location of the
shear thinning and placing to facilitate entrance of the polymer
composition into the web.
62. The method of controlled placement according to claim 61
wherein the distorting comprises stretching.
63. The method of controlled placement according to claim 62
wherein the stretching is by passage of the web under a roller
rotating against the web so as to move the web past a localized
area where the polymer composition is placed into the web.
64. The method of controlled placement according to claim 62
wherein the distorting by stretching is by passage of the web
between a first roller and a second roller that is delivering the
polymer composition onto the web.
65. The method of controlled placement according to claim 64
wherein the distorting by stretching is by passage between rollers
rotating in the same direction.
66. The method of controlled placement according to claim 65
wherein the rollers rotate opposite to movement of the web past the
localized area.
67. The method of controlled placement according to claim 64
wherein the distorting by stretching is between first and second
rollers at least one of which exhibits a gravure surface.
68. The method of controlled placement according to claim 64
wherein the distorting by stretching is between first and second
rollers at least one of which exhibits a smooth surface.
69. The method of controlled placement according to claim 62
wherein the distorting by stretching is by passage of a tensioned
web against a bar knife.
70. The method of controlled placement according to claim 69 that,
after the distorting by stretching under a bar knife, further
comprises: scraping the porous web with a scraper so as to scrape
excess polymer composition off the surface of the web.
71. The method of controlled placement according to claim 70
wherein the scraping is under pressure against a tensioned web so
that further pressure is exerted against the polymer composition so
as to again reduce its viscosity and again place it, under this
further pressure, into the porous web.
72. The method of controlled placement according to claim 71
wherein the pressured scraping simultaneously occurs at a plurality
of locations on the tensioned web as it moves under tension past a
like plurality of scrapers.
73. The method of controlled placement according to claim 59
wherein the shear thinning and placing comprises: first pressuring
in a pressured application stage that delivers the polymer
composition onto and into the porous web under pressure; second
pressuring in a pressured excess-removal stage that further
pressures the polymer composition that is in and upon the porous
web resulting from the first pressuring further into the web while
removing excess polymer composition that is upon and in the
web.
74. The method of controlled placement according to claim 73
wherein the first pressuring comprises: rolling the polymer
composition onto and into the porous web under pressure; and
wherein the second pressuring comprises: scraping the porous web
with a scraper so as to exert pressure thereagainst while removing
excess polymer composition by action of scraping.
75. The method according to claim 74, wherein the rolling is
between two rollers rotating in the same direction thereby
stretching the web between the rollers simultaneously so that the
polymer composition is rolled onto and into the porous web under
pressure.
76. A method of controlled placement according to claim 53 wherein
the porous web has a plurality of structural elements with
intersticial spaces therebetween and the polymer composition is
selectively placed to encapsulate at least some of the structural
elements of the web leaving some of the intersticial spaces
open.
77. A method of controlled placement according to claim 53 wherein
the polymer composition is selectively placed in an internal layer
within said web positioned in a region extending through the web in
a direction generally spaced from at least one major surface of
said web.
78. A method of controlled placement according to claim 76 wherein
the polymer composition is also selectively placed in an internal
layer within said web positioned in a region extending through the
web in a direction generally parallel to and spaced from at least
one major surface of said web.
79. A method of controlled placement in accordance with claim 60
wherein the shear thinning and placing is controlled to also
selectively place the polymer composition in an internal layer
within said web positioned in a region extending through the web in
a direction generally spaced from at least one major surface of
said web.
80. A method of controlled placement in accordance with claim 53
wherein said web has a plurality of structural elements with
intersticial spaces therebetween and said selective placing, is
encapsulation of at least some of the structural elements of said
web, leaving at least some of the intersticial spaces open.
81. A method of controlled placement according to claim 53 wherein
said porous web has a plurality of structural elements with
interstitial spaces therebetween and the polymer composition is
selectively placed as an intern al layer within said web positioned
in a region extending through the web in a direction generally
spaced from at least one major surface of said web.
82. A method of controlled placement according to claim 81 wherein
the polymer composition is also selectively placed to encapsulate
at least some of the structural elements of the web.
83. A method according to claim 53 wherein said porous web has a
number of open cells and said polymer composition is selectively
placed to line at least some of the individual cell walls leaving
at least some of the cells open.
84. A method according to claim 83 wherein the polymer composition
is also selectively placed in an internal layer within said web
positioned in a region extending through the web in a direction
generally spaced from at least one major surface of said web.
85. A method of controlled placement according to claim 53 wherein
said shear thinning and placing includes urging one or more blades
against the tensioned web and polymer composition.
86. A method of controlled placement according to claim 85
including controlling the force of each blade against said moving
web.
87. A method of controlled placement according to claim 85 further
comprising controlling the tension of the web as it passes each
blade.
88. A method of controlled placement according to claim 85
comprising controlling the temperature of each blade.
89. A method of controlled placement according to claim 85
comprising controlling the entrance angle of the web and the exit
angle of the web from each blade.
90. A method of controlled placement according to claim 85
comprising controlling the resonance of each blade.
91. A method of controlled placement according to claim 85
comprising the longitudinal tension of said moving web.
92. A method of controlled placement according to claim 85 further
comprising the step of applying a transverse force to said web
after shear thinning and placing.
93. A method of controlling the placement of a polymer composition
into a porous substrate having a matrix of open cells therein
comprising the steps of: applying tension longitudinally to said
substrate; applying a curable polymer composition having a
viscosity sufficient to line the walls of said cells to at least
one surface of said substrate; moving against said surface of the
tensioned substrate at least one of a uniformly applied compressive
force and a uniformly applied localized shear force to selectively
distribute said composition within said substrate, at least
partially individually lining cell walls of at least some of said
cells with said composition, and leaving most of said cells
open.
94. The method of claim 93 wherein said polymer composition has a
viscosity greater than about 5,000 and less than about 2,000,000
centipoise.
95. The method of claim 94 wherein the substrate is subjected to
conditions sufficient to cure the polymer composition in said
substrate.
96. The method of claim 95 wherein said curing is accomplished by
heat.
97. The method of claim 95 wherein said curing is accomplished by
radiation.
98. A method for making a fluorochemical and silicone resin treated
substrate having breathability, water resistance and rewashability
comprising the successive steps of: (a) impregnating a porous
substrate having generally open cells therein, with a
fluorochemical; (b) applying a curable silicone polymer composition
and concurrently applying a transversely exerted localized
compressive force against one surface of the substrate; (c) moving
relative to said surface of the substrate a substantially rigid
shearing means which exerts transversely applied localized shear
forces against said surface and which wipes away exposed portions
of silicone polymer composition on said surface, thereby forming an
internal layer of silicone polymer composition; and (d) curing the
silicone polymer composition in said substrate.
99. The method of claim 98 wherein said fluorochemical impregnated
substrate is both longitudinally and laterally tensioned.
100. The method of claim 98 wherein said porous substrate is a
leather.
101. The method of claim 98 wherein said porous substrate is a
porous paper.
102. The method of claim 98 wherein said porous substrate is an
open celled plastic.
103. The method of claim 98 wherein said porous substrate is an
open celled sheet structure.
104. The method of claim 98 wherein said substrate is a synthetic
leather.
105. The method of claim 98 wherein said substrate comprises a
layer of an open celled, porous, flexible material and a layer of a
non-porous flexible material.
106. The method of claim 98 wherein said fluorochemical
impregnating is carried out by the steps comprising: (a)
substantially completely saturating said substrate with a
dispersion of a fluorochemical containing composition in a carrier
liquid; (b) compressing the saturated substrate to remove therefrom
excess portions of said dispersion; and (c) heating said substrate
to evaporate said carrier liquid therefrom.
107. A method of controlling the placement of a polymer composition
into a porous web comprising the steps of: (a) tensioning a
flexible, porous web comprised of fibers having interstices
therebetween, said web having generally opposed surfaces, (b)
applying a curable polymer composition having a viscosity greater
than about 1,000 centipoise to at least one surface of said web and
then: (c) moving over and against said surface of the tensioned web
at least one of a uniformly applied localized shear force or a
uniformly applied localized compressive force to: (1) distribute
said composition generally uniformly within said web, (2) at least
partially individually encapsulate at least some of said fibers
with said composition, and (3) leave at least some of said
interstices open.
108. The method of claim 107 wherein the web is subjected to
conditions sufficient to cure said polymer composition in said
web.
109. The method of claim 108 wherein said curing is accomplished by
heat.
110. The method of claim 109 wherein said curing is accomplished by
radiation.
111. A method for making a fluorochemical and silicone resin
treated web having breathability, water resistance and
rewashability comprising the successive steps of: (a) substantially
uniformly impregnating the fibers of a porous web with a
fluorochemical; (b) tensioning said fluorochemical impregnated web
while sequentially: (1) first applying a curable silicone polymer
composition to a surface of said web while applying a transversely
exerted localized compressive force against said surface, and (2)
moving a substantially rigid, shearing means which transversely
exerts an applied, localized shear force against said surface of
the web to remove exposed portions of said silicone polymer
composition from said surface, thereby individually encapsulating
at least some of said fibers with said silicone polymer
composition; and (c) curing the silicone polymer composition in the
web.
112. The method of claim 111 wherein said porous web is a woven
fabric.
113. The method of claim 111 wherein said porous web is a non-woven
fabric.
114. The method of claim 111 wherein said fibers are comprised of a
synthetic polymer.
115. The method of claim 114 wherein said synthetic polymer is
selected from the group consisting of polyamides, polyolefins,
polyesters, regenerated cellulose and cellulose acetate.
116. The method of claim 111 wherein said fibers are comprised of
natural fibers.
117. The method of claim 116 wherein said natural fibers are
selected from the group consisting of cotton, linen, wool and
silk.
118. The method of claim 111 wherein said fibers are comprised of a
mixture of natural fibers and synthetic fibers.
119. The method of claim 118 wherein said fibers are comprised of a
blend of cotton fibers and polyester fibers.
120. The method of claim 111 wherein said web is a laminate of a
woven fabric and a porous, flexible, non-woven substrate.
121. The method of claim 120 wherein said substrate comprises a
non-woven fabric.
122. The method of claim 111 wherein said fluorochemical
impregnating is carried out by the steps comprising: (a)
substantially completely saturating said web with a dispersion of a
fluorochemical composition in a carrier liquid; (b) compressing the
saturated web to remove therefrom excess portions of said
dispersion; and (c) heating said web to evaporate said carrier
liquid therefrom.
123. The method of claim 122 wherein the fluorochemical impregnated
web has a weight increase in the range of about 0.01 to about 5
weight percent of the weight of the untreated web.
124. The method of claim 123 wherein the silicone polymer
composition impregnated web has a weight increase in the range of
about 5 to about 200 weight percent compared to the weight of the
untreated web.
125. Apparatus as set forth in claim 2 wherein said polymer
composition includes an additive and at least some of said additive
in selectively placed on the surface of the encapsulated structural
elements.
126. Apparatus is set forth in claim 3 wherein said polymer
composition includes an additive and at least some of said additive
is placed on one or both surfaces of the internal layer.
127. Apparatus as set forth in claim 4 wherein said polymer
composition includes an additive and at least some of said additive
is placed on the surface of the encapsulated structural elements
and at least some of said additive is placed on one or both
surfaces of the internal layer.
128. Apparatus as set forth in claim 1 wherein said polymer
composition includes an additive and at least some of said additive
is selectively placed on one or both surfaces of said web.
129. A method of controlled placement as set forth in claim 76
wherein the polymer composition includes an additive and at least
some of said additive is selectively placed on the surface of the
encapsulated structural elements.
130. A method of controlled placement is set forth in claim 77
wherein the polymer composition includes an additive and at least
some of said additive is selectively placed on one or both surfaces
of the internal layer.
131. A method of controlled placement as set forth in claim 78
wherein the polymer composition includes an additive and at least
some of said additive is placed on the surface of the encapsulated
structural elements and at least some of said additive is placed on
one or both surfaces of the internal layer.
132. A method of controlled placement as set forth in claim 53
wherein said polymer composition includes an additive and at least
some of said additive is selectively placed on one or both surfaces
of said web.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 08/017,855 filed on Feb. 16, 1993, now U.S.
Pat. No. 5,418,051 issued May 23, 1995; which was a continuation of
U.S. patent application Ser. No. 07/680,645 filed on Apr. 2, 1991,
now U.S. Pat. No. 5,209,965 issued May 11, 1993; which was a
continuation of U.S. patent application Ser. No. 07/319,778 filed
on Mar. 10, 1989, now U.S. Pat. No. 5,004,643, issued Apr. 2, 1991;
which was a continuation in part of U.S. patent application Ser.
Nos. 167,630; 167,643; 167,797; and 167,869 all filed on Mar. 14,
1988; and all incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to methods of and apparatus
for the introduction of sufficient energy to controllably and
selectively place a polymer composition into a porous web. The
present invention more particularly relates to methods of and
apparatus for the controlled placement of a curable, shear
thinning, polymer composition into a web. The controlled placement
is preferably performed through the energy controlled viscosity and
rheology modified placement of the polymer controlled manner by 1)
applying the polymer composition onto a surface of a web, 2) shear
thinning the composition and placing it into the web, and 3) curing
the polymer composition. This method and apparatus produces a web
that either has some of its fibers or structural elements
encapsulated by the polymer composition while at least some of the
interstitial spaces of the web are open; or has an internal layer
extending through the web in a direction generally spaced from at
least one major surface thereof; or has both encapsulated
structural elements and an internal layer of polymer
composition.
[0004] 2. Description of Related Art
[0005] In the prior art, it has been proposed to treat porous webs,
especially fabrics, with silicone resins and also with
fluorochemicals. Conventional treatments of webs fall into the
general categories of (i) surface coatings and (ii) saturations or
impregnations.
[0006] For example, U.S. Pat. Nos. 3,436,366; 3,639,155; 4,472,470;
4,500,584; and 4,666,765 disclose silicone coated fabrics. Silicone
coatings are known to exhibit relative inertness to extreme
temperatures of both heat and cold and to be relatively resistant
to ozone and ultraviolet light. Also, a silicone coating can
selectively exhibit strength enhancement, flame retardancy and/or
resistance to soiling. Fluorochemical treatment of webs is known to
impart properties, such as soil resistance, grease resistance, and
the like.
[0007] Prior art fluorochemical and silicone fabric treatment
evidently can protect only that side of the fabric upon which they
are disposed. Such treatments significantly alter the hand, or
tactile feel, of the treated side. Prior silicone fabric coatings
typically degrade the tactile finish, or hand, of the fabric and
give the coated fabric side a rubberized finish which is not
appealing for many fabric uses, particularly garments.
[0008] U.S. Pat. No. 4,454,191 describes a waterproof and
moisture-conducting fabric coated with a hydrophilic polymer. The
polymer is a compressed foam of an acrylic resin modified with
polyvinyl chloride or polyurethane and serves as a sort of
"sponge", soaking up excess moisture vapor. Other microporous
polymeric coatings have been used in prior art attempts to make a
garment breathable, yet waterproof.
[0009] Various polyorganosiloxane compositions are taught in the
prior art that can be used for making coatings that impart
water-repellency to fabrics. Typical of such teachings is the
process described in U.S. Pat. No. 4,370,365 which describes a
water repellent agent comprising, in addition to an
organohydrogenpolysiloxane, either one or a combination of linear
organopolysiloxanes containing alkene groups, and a resinous
organopolysiloxane containing tetrafunctional and monofunctional
siloxane units. The resultant mixture is catalyzed for curing and
dispersed into an aqueous emulsion. The fabric is dipped in the
emulsion and heated. The resultant product is said to have a good
"hand" and to possess waterproofness.
[0010] This type of treatment for rendering fabrics water repellent
without affecting their "feel" is common and well known in the art.
However, it has not been shown that polyorganosiloxanes have been
coated on fabrics in such a way that both high levels of resistance
to water by the fibers/filaments and high levels of permeability to
water vapor are achieved. As used herein, the term "high levels of
permeability to water vapor" has reference to a value of at least
about 500 gms/ m.sup.2/day, as measured by ASTM E96-80B. Also, as
used herein, the term "high level of waterproofness" is defined by
selective testing methodologies discussed later in this
specification. These methodologies particularly deal with water
resistance of fabrics and their component fibers.
[0011] Porous webs have been further shown to be surface coated in,
for example, U.S. Pat. Nos. 4,478,895; 4,112,179; 4,297,265;
2,893,962; 4,504,549; 3,360,394; 4,293,611; 4,472,470; and
4,666,765. These surface coatings impart various characteristics to
the surface of a web, but do not substantially impregnate the web
fibers. Such coatings remain on the surface and do not provide a
film over the individual internal fibers and/or yarn bundles of the
web. In addition, such coatings on the web surface tend to wash
away quickly.
[0012] Prior art treatments of webs by saturation or impregnation
also suffer from limitations. Saturation, such as accomplished by
padbath immersion, or the like, is capable of producing variable
concentrations of a given saturant chemical.
[0013] To treat a flexible web, by heavy saturation or impregnation
with a polymer material, such as a silicone resin, the prior art
has suggested immersion of the flexible web, or fabric, in a
padbath, or the like, using a low viscosity liquid silicone resin
so that the low viscosity liquid can flow readily into, and be
adsorbed or absorbed therewithin. The silicone resin treated
product is typically a rubberized web, or fabric, that is very
heavily impregnated with silicone. Such a treated web is
substantially devoid of its original tactile and visual properties,
and instead has the characteristic rubbery properties of a cured
silicone polymer.
[0014] U.S. Pat. No. 2,673,823 teaches impregnating a polymer into
the interstices of a fabric and thus fully filling the interstices.
This patent provides no control of the saturation of the fabric. It
teaches full saturation of the interstices of the fabric.
[0015] The prior art application of liquid or paste compositions to
textiles for purposes of saturation and/or impregnation is
typically accomplished by an immersion process. Particularly for
flexible webs, including fabric, an immersion application of a
liquid or paste composition to the web is achieved, for example, by
the so-called padding process wherein a fabric material is passed
first through a bath and subsequently through squeeze rollers in
the process sometimes called single-dip, single-nip padding.
Alternatively, for example, the fabric can be passed between
squeeze rollers, the bottom one of which carries the liquid or
paste composition in a process sometimes called double-dip or
double-nip padding.
[0016] Prior art treatment of webs that force a composition into
the spaces of the web while maintaining some breathability have
relied on using low viscosity compositions or solvents to aid in
the flow of the composition. U.S. Pat. No. 3,594,213 describes a
process for impregnating or coating fabrics with liquified
compositions to create a breathable fabric. This patent imparts no
energy into the composition to liquify it while forcing it into the
spaces of the web. The composition is substantially liquified
before placement onto and into the web. U.S. Pat. No. 4,588,614
teaches a method for incorporating an active agent into a porous
substrate. This patent utilizes a solvent to aid in the
incorporation of the active agent into the web.
[0017] Prior art apparatus for the coating of webs, including
fabrics, generally deposits a coating onto the fabric at a desired
thickness. Coating at a predetermined thickness can be achieved by
deposition of coating material or by the scraping of a coating upon
the fabric by knives. Flexible webs are generally urged between
oppositely disposed surfaces, one of which would be a doctoring
blade or drag knife. The blade or knife smooth the coating and
maintain the thickness of the coating to a desired thickness. For
example, it is possible to apply a relatively thick silicone liquid
elastomer coating to a rough web, typically of fiberglass, in order
to make architectural fabric as is taught in U.S. Pat. No.
4,666,765. In this example, the drag knives are set to a thickness
of about 2 to 10 mils thicker than the web thickness. This setting,
depending on the coating speed, can yield a base coat thickness of
approximately 3 to 12 mils thicker than the web thickness.
[0018] Various types of coatings, and various coating thicknesses,
are possible. However, a general principle of coating machinery is
that the coating material is swept, or dragged, along the surface
of the fabric. No special attention is normally given to any
pressured forcing of the coating into the fabric, therein making
the coating also serve as an impregnant. Of course, some coating
will be urged into surface regions of the fabric by the coating
process. Generally, however, application of high transversely
exerted (against a fiber or web surface) forces at the location of
the coating deposition and/or smoothing is not desired in the prior
art processes because it is the goal of the prior art coating
processes to leave a definite thickness of coating material upon a
surface of the fabric, and not to scrape the fabric clean of
surface-located coating material.
[0019] One prior art silicone resin composition is taught by U.S.
Pat. Nos. 4,472,470 and 4,500,584, and includes a vinyl terminated
polysiloxane, typically one having a viscosity of up to about
2,000,000 centipoises at 25.degree. C., and a resinous
organosiloxane polymer. The composition further includes a platinum
catalyst, and an organohydrogenpolysiloxane crosslinking agent, and
is typically liquid. Such composition is curable at temperatures
ranging from room temperature to 100.degree. C. or higher depending
upon such variables as the amount of platinum catalyst present in
the composition, and the time and the temperature allowed for
curing.
[0020] Such compositions may additionally include fillers,
including finely divided inorganic fillers. Silicone resin
compositions that are free of any fillers are generally transparent
or translucent, whereas silicone resin compositions containing
fillers are translucent or opaque depending upon the particular
filler employed. Cured silicone resin compositions are variously
more resinous, or hard, dependent upon such variables as the ratio
of resinous copolymer to vinyl terminated polysiloxane, the
viscosity of the polysiloxane, and the like.
[0021] Curing (including polymerization and controlled
crosslinking) can encompass the same reactions. However, in the
fabric finishing arts, such terms can be used to identify different
phenomena. Thus, controllable and controlled curing, which is
taught by the prior art, may not be the same as control of
crosslinking. In the fabric finishing arts, curing is a process by
which resins or plastics are set in or on textile materials,
usually by heating. Controlled crosslinking may be considered to be
a separate chemical reaction from curing in the fabric finishing
arts. Controlled crosslinking can occur between substances that are
already cured. Controlled crosslinking can stabilize fibers, such
as cellulosic fibers through chemical reaction with certain
compounds applied thereto. Controlled crosslinking can improve
mechanical factors such as wrinkle performance and can
significantly improve and control the hand and drape of the web.
Polymerization can refer to polymer formation or polymer
growth.
SUMMARY OF THE INVENTION
[0022] The present invention includes methods and apparatus for
controlling a porous web under tension, for applying a curable or
semi-curable, shear thinnable polymer composition onto the surface
of the web, for shear thinning the polymer composition, and placing
it into the web to position the polymer within the web in a certain
manner, and for partially or fully curing the polymer composition.
The methods and apparatus of this invention control the placement
of the composition into the web to either encapsulate the
structural elements (i.e., the fibers or filaments) making up the
web leaving at least some of the interstitial spaces open or
providing an internal layer of polymer between the upper and lower
surfaces of the web, or some combination of the foregoing.
[0023] The methods and apparatus of the present invention permits
the application of the polymeric composition onto the surface of
the web by a variety of means. After the polymer is applied to the
surface of the web, the polymer composition is preferrably
immediately shear thinned to controllably and significantly reduce
its viscosity and place it into selected places within the web. To
aid in this process, the web is preferably distorted, typically by
stretching at the location of the shear thinning. This distortion
facilitates the entrance of the polymer composition into the web by
creating a double or dual shear thinning. In the case of the web,
this is produced by the combination of the edge condition of the
blade, the engineered shear thinnable polymer, the speed of the
web, and the subsequent repositioning of the fibers and filaments
after their immediate passage under the edge of the blade.
[0024] Controlled placement of the polymer composition within a web
may be performed by a basic embodiment of a machine in accordance
with the present invention, that is as simple as an applicator to
apply viscous polymer to the surface of the web, a pair of
facilities for applying tension to a section of the web and a blade
forced against the web in the section under tension. The web is
pulled under tension past the blade, or, alternatively, the blade
is moved relative to the web, and the forces generated by the blade
cause the polymer composition to flow into the three-dimensional
matrix of the web, and controllably be extracted out of the web
leaving a thin film of polymer encapsulating selected fibers, or an
internal layer of polymer, or both. Tension on the web is
preferably released thereafter, and the web is cured.
[0025] The present invention includes novel methods and apparatus
for manufacturing webs, fibers and fabrics that have certain
desirable physical qualities such as water resistance, increased
durability, and improved barrier qualities by combining the use of
encapsulated fibers and filaments and a breathable or controlled
pore size internal coating with a controlled surface chemistry
modification and the like. Such webs, fibers and fabrics can be
used to prepare a wide variety of products including, but not
limited to, carpets, specialized clothing, career apparel,
bioengineered surfaces for diagnostic applications, and upholstery.
By use of the present invention, webs, fibers and fabrics can be
manufactured with a wide variety of desired physical
characteristics.
[0026] Methods and apparatus of the present invention can treat
webs or fabrics which are generally flat or planar with great
internal precision of the internal placement, by combining the use
of encapsulated fibers and filaments and a breathable or controlled
pore size internal layer, with a controlled surface chemistry
modification. Surface chemistry is controlled by using sufficient
web tension and frontal blade energy to dislodge the fluorochemical
from the web which is then caused to surface orient and/or bloom.
The webs or fabrics can comprise fibers in the form of
monofilaments, yarns, staples, or the like. The webs or fabrics can
also be comprised of a matrix having open cells or pores therein.
The webs or fabrics may be a fabric which is woven or non-woven
with fibers that can be of any desired composition. The webs or
fabrics will generally be tensionable, but not too weak or
elastomeric to be processed in accordance with the teachings of the
present invention. Any web that is too weak or elastomeric can be
treated in accordance with the subject invention if it is laminated
to a support backing of paper, film, such as Mylar, or the like and
controllably stretched or not stretched prior to applying the
backing, thereby setting the condition under which it is stabilized
so that it can be treated in accordance with this invention.
[0027] The methods and apparatus of this invention are also
applicable to treating discrete sheets or pieces of webs such as
papers, film sheets, foam sheets, leather hides, woven and
non-woven sheets, and the like. The sheet is fed into the apparatus
and stops. It is placed under tension and polymer is applied. Rigid
or non-rigid blades are moved across the surface of the sheet-to
cause the controlled placement of the polymer within the sheet as
previously described. A non-rigid blade can be flexible but must
have sufficient shearing capability.
[0028] Webs treated by the methods and apparatus of the present
invention contain a curable or semi-curable polymer or copolymer
that may contain monomers that are present as a film, coating, or
layer within a web that envelopes or encapsulates at least a
portion of the fibers or cell or pore walls of the web. The
internal layer is a region generally spaced from the outer surfaces
of the web which is substantially continuously filled by the
combination of the polymers controllably placed therein and the
fibers and filaments of the web in this region. The interstices or
open cells in the region of the internal layer are also
substantially filled. The outer surfaces of the web are
substantially free of any polymer deposits other than the thin film
encapsulation of the surface fibers and filaments. However, the web
remains breathable and is either water resistant or waterproof. The
thickness of the internal layer is generally in the range of 0.01
to 50 microns.
[0029] At a microscopic level, a web treated in accordance with the
present invention, for example, a fabric, can be regarded as being
a complex structure, but generally the internal layer is
discernable under microscopic examination as shown in the
accompanying scanning electron microscope photographs that will be
discussed hereinafter.
[0030] Depending upon the conditions used to produce it, a web
produced in accordance with the present invention can
characteristically and preferably exhibit a soft hand and
flexibility that is comparable to the hand and flexibility of the
untreated web. In some cases, the difference between the hand and
the feel of the treated and untreated webs may not be perceptible,
but may be engineered to be altered through the controlled
crosslinking of the polymer. This is particularly surprising in
view of the substantial amount of polymer being added to the web. A
treated web has a breathability which, by a present preference, can
approach a high percentage of the untreated web notwithstanding the
relatively large amount of polymer present.
[0031] A polymer composition having a viscosity in the range of
greater than 1,000 centepoise but less than 2,000,000 centepoise is
preferably used to produce the treated webs. If desired, additives
or modifiers can be admixed with such a composition to adjust and
improve properties of such composition or web, such as viscosity
and/or rheology, combustibility, reflectivity, flexibility,
conductivity, light fastness, mildew resistance, rot resistance,
stain resistance, grease resistance, and the like. In general, a
web treated in accordance with this invention exhibits enhanced
durability. These additives are generally controlled by the
engineered shear thinning polymer composition and the method and
apparatus of this invention to be oriented and surface exposed on
the surface of the thin film on the encapsulated fibers, or on one
or both surfaces of the internal layer, or on one or both surfaces
of the web, or some combination of the above.
[0032] A web made by the present invention can preserve much, or
even substantially all, of its original untreated hand even after
an extended period of use while demonstrating excellent abrasion
resistance. In contrast, an untreated web typically loses its
original hand and displays reduced abrasion resistance after an
extended period of use. This is achieved by the formation of an
internal layer that prevents new fiber surfaces from being exposed,
thereby minimizing the amount of untreated surfaces that degrade
much faster than the treated fibers.
[0033] A web treated by this invention can undergo a large number
of machine washings with detergent without experiencing appreciable
or significant change or deterioration. The polymer matrix
composition prolongs the use and service life of a web, usually by
at least an order of magnitude, depending on such factors as web
type, extent and type of treatment by the teachings of this
invention, and the like.
[0034] Optionally, and as indicated above, agents or additives
carried by the polymer composition into a web can be stably fixed
and selectively placed in the web with the cured polymer. For
example, agents such as ultraviolet light absorbers, dulling
agents, reflectivity enhancers, antimicrobial agents, flame
resistant agents, heat absorbant, anti-static agents, and the like,
which modify a web's response to light and radiation are desirably
located substantially upon the surfaces of the web's fibers. When
these agents are incorporated into the enveloping polymer film, it
appears that they are retained where they are deposited. A present
preference for ultraviolet resistant webs in the practice of this
invention is to employ a silicone polymer composition that contains
a benzophenone.
[0035] In addition, the present invention is directed to methods
and apparatus for making polymer encapsulated and internally coated
webs. Such methods and apparatus includes means for tensioning a
porous, flexible web; means for applying a curable, shear
thinnable, polymer composition thereto; and means for applying a
localized shear force sufficient to cause the controlled shear
thinning of an engineered polymer over and against one or both
surfaces of the tensioned web. The shear force is sufficient to
shear thin the polymer, to selectively distribute and place the
polymer composition within the web as an internal layer in a region
extending generally in spaced relationship to the surfaces of the
web and to generally envelop surface portions of at least some of
the web fibers or form a lining of the cells or pores of the web.
The internal layer is not necessarily flat but may undulate or
meander through the web, occasionally even touching one or both
surfaces of the web. Alternatively, the shear force and other
variables are controlled to encapsulate at least some of the
internal and external fibers of the web without forming an internal
layer. Also, control of the methods and apparatus can result in a
treated web having a combination of an internal layer and
encapsulation of at least some of the fibers of the web leaving at
least some of the interstitial spaces open. The web is then
optionally interveningly stored, or is (preferably) immediately
subjected to curing conditions (heat, moisture and/or radiation)
which converts the polymer composition as deposited in the web into
a solid elastomeric polymer. The web can be semi-cured or partially
cured and can be finally cured or post cured at a later time.
[0036] Various other and further features, embodiments, and the
like which are associated with the present invention will become
apparent and better understood to those skilled in the art from the
present description considered in conjunction with the accompanying
drawings wherein presently preferred embodiments of the invention
are illustrated by way of example. It is to be expressly
understood, however, that the drawings and the associated
accompanying portions of this specification are provided for
purposes of illustration and description only, and are not intended
as limitations on the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a graphical plot illustrating the flow of a
silicone polymer composition over time upon and in fabrics both
pretreated and untreated with water repellent chemicals, such as
fluorochemicals.
[0038] FIG. 2 is a plan view of a prior art silicone polymer
treated fabric magnified 150 times.
[0039] FIG. 3a is a photomicrograph of a fabric of the invention
magnified 120 times.
[0040] FIG. 3b is a cross section of a fiber bundle fabric of FIG.
3a magnified 600 times.
[0041] FIG. 3c is a view of the side of the fabric of FIG. 3a that
is the opposite of the side to which silicone polymer was
applied.
[0042] FIGS. 4a and 4b illustrate diagrammatically one embodiment
of a method and apparatus suitable for use in the practice of the
present invention.
[0043] FIG. 5 is a diagrammatic representation illustrating the
process in accordance with the present invention.
[0044] FIG. 6 illustrates diagrammatically another embodiment of a
methods and apparatus suitable for use in the practice of the
present invention.
[0045] FIG. 7 illustrates diagrammatically another embodiment of a
method and apparatus suitable for use in the practice of the
present invention.
[0046] FIGS. 8a through 8d are graphs illustrating ways of plotting
rheological behavior.
[0047] FIG. 9 is a schematic vector diagram illustrating surface
tension forces.
[0048] FIG. 10 is a graph relating contact angle over a smooth,
solid surface.
[0049] FIGS. 11a through 11d show representative velocity
profiles.
[0050] FIGS. 12a through 12c illustrate diagrammatically other
methods and apparatus suitable for use in the practice of the
present invention.
[0051] FIGS. 13a through 13c are scanning electron microscope
photomicrographs of another representative fabric made in
accordance with of the present invention.
[0052] FIG. 14 illustrates diagrammatically another and presently
preferred embodiment of methods and apparatus suitable for use in
the practice of the present invention.
[0053] FIGS. 15a through 15i are scanning electron microscopy (SEM)
photomicrographs and elemental analyses which depict various
results in fabrics, fibers and filaments from back scatter
evaluation tests.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0054] The following description is of the best presently
contemplated mode of carrying out the invention. This description
is made for the purpose of illustrating the general principles of
the inventions and should not be taken in a limiting sense.
[0055] The present invention relates to methods and apparatus for
manufacturing a treated web. The subject methods and apparatus
involve the control of numerous variables, including, without
limitation, web tension (both overall web tension as well as the
web tension immediately before and after each individual blade),
angle of entry of web into each blade, blade angle in relation to
horizonal reference point, blade pressure against moving web, angle
of exit of web from each blade, web speed, number of blades, the
pressure of the leading nip rolls, the pressure of the trailing nip
rolls, static control, thickness of each blade, bevel on each
blade, oven cure temperature, oven cure dwell time, blade
temperature and blade surfaces and edge conditions and blade
finish.
[0056] Other variables that affect the finished product, but are
not directly related to the methods and apparatus, include, without
limitation, the polymer blend, the starting viscosity of the
polymer composition, accelerators added to the polymer composition,
additives added to the polymer composition, the type of web used,
ambient temperature, humidity, airborne contaminants, lint on web,
pre-treatment of web, sub-web surface temperature, and web moisture
content.
[0057] With respect to the blades, the temperature of the blade can
be kept cool to keep the polymer composition from curing
prematurely. This can be accomplished by passing a coolant through
or around the blade or by other means well known in the art.
Alternatively, the blade could be heated by passing a heated fluid
around or through the blade, if desired to improve or alter the
viscosity and rheology for the required changes in the polymer
necessary to achieve a specific product.
[0058] The blade finish is also important. A hard, smooth surface
of both blade face and edges is desirable to shear thin the polymer
and keep it flowing and to maximize friction or selectively create
shear forces between the web, the polymer, and blade(s). For some
applications, the blades should preferably remain rigid in all
dimensions and have minimal resonance in order to get uniform web
treatment.
[0059] The apparatus has facilities for rotating the angle of each
blade .+-.90.degree. from the vertical. In order to vary the shear
and placement forces of the blade against the web, polymer and
additives, adjustment facilities are provided for moving the blade
vertically up and down and moving the blade forward and backward
horizontally. All three axis are important for creating the desired
control which causes the encapsulated fibers and/or filaments, the
additive placement and orientation on the fiber and filaments, the
optional internal layer, and the controlled thickness of the
encapsulating films or internal layer. The lateral placement of
each blade relative to the other is also important and facilities
are provided for allowing lateral movement of each blade toward and
away from each other. The lateral placement of each blade controls
the micro tension and elastic vibration of the web between the
preceding roll and the blade, thereby controlling the web after the
immediate exit of the web from the blade and controlling the Coanda
Effect, as described in U.S. Pat. No. 4,539,930, so that controlled
placement of the internal layer takes place.
[0060] Changing the tension of the web results in changes
internally in the web, such as the position of the internal layer
of the web, as well as how much or how little fiber encapsulation
occurs, and the thickness of the film encapsulating the individual
fibers or filaments.
[0061] At the leading edge of the blade, the web is stretched
longitudinally and the polymer is simultaneously and dynamically
shear thinned, placed into the web, and partially extracted from
the web, thereby leaving encapsulated fibers and filaments and/or
an internal layer. As the web passes the leading edge of the blade,
the elastic recovery forces of the web combined with the relaxation
or elastic recovery of the fibers and filaments causes fiber
encapsulation and the surface chemistry modification (or bloom). It
is believed that this occurs by the popping apart of the individual
fibers and filaments. The fibers and filaments either pull the
polymer from the interstitial spaces or the rheology of the polymer
attracts it to the fibers and filaments or some combination of the
two. The end result is that the polymer in the interstitial spaces
moves to the fibers and filaments as they move or snap apart,
thereby creating encapsulated fibers and filaments. At the bottom
surface of the blade, the thickness, depth, and controlled
placement of the internal layer is determined. A wider blade
results in a thicker internal layer of polymer. Further, the
dynamics of stretch and relaxation of the fibers provides for an
even energy necessary for the thin film encapsulation of the
polymer composition over the fibers.
[0062] Passing the treated web through the exit nip rolls pushes
the fibers or structural elements of the web together. The hardness
of and the material of the exit nip rolls affects the finished web.
The exit nip rolls could be either two rubber rolls or two steel
rolls, or one steel roll and one rubber roll, and the rubber rolls
could be of different durometers. Further, the variation of the
hardness of one or both nip rolls changes the contact area or
footprint between the nip rolls and the web as the web passes
therebetween. With a softer roll there is a larger contact area and
the web is capable of retaining the (a) thin film encapsulation of
the individual fibers and filaments, (b) the controlled placement
of the internal coating, and (c) controlled placement of the
additives in (a) and (b). With a harder roll there is a smaller
contact area which is appropriate for heavier webs.
[0063] Additional controllable variables include the various
controls of each blade, the nip rolls durometer, the nip release
effect, the nip surface characteristics, the guidance, and the
pre-treatment of the substrate. Some of the controllable variables
are: 1) web tension, 2) angle of entry of fabric into the blade,3)
blade angle in reference to horizontal position, 4) blade pressure
against fabric (blade height), 5) angle of exit of fabric from
blade, 6) web speed, 7) number of blades, 8) initial rheology and
viscosity of polymers, 9) nip pressure, 10) entry nip pressure 11)
static control, 12) blade thickness and shape, 13) polymers and
polymer blends, 14) accelerators and inhibitors added to polymers,
15) additives in polymers, 16) oven cure temperature, 17) oven cure
dwell time, 18) substrate type, 19) ambient polymer temperature,
20) humidity, 21) degree web is deformed under lateral tension, and
22) airborne contaminants and lint on the web. Control of the above
variables affects: (a) the thin film encapsulation of the
individual fibers and filaments, (b) the controlled placement of
the internal coating, and (c) the controlled placement of the
additives in (a) and (b).
[0064] An increase in web tension causes less polymer to be applied
to the web, and also, more of what is applied to be extracted from
the web. Web tension occurs between the entrance pull stand and the
exit pull stand. The primary tension is a result of the
differential rate between the driven entrance pull stand and the
driven exit pull stand whereby the exit pull stand is driven at a
rate faster than the entrance pull stand. Other factors which
effect tension are (1) the blade roll diameter, (2) the vertical
depth of the blade(s), (3) the durometer of the entrance pull stand
roll and rubber roll of the exit pull stand, and (4) the friction
as the web passes under the blade(s). The larger the blade roll
diameter, the higher the tension of the web. If the drive rate of
the web remains constant, then increasing the depth of the blade
into the web creates a greater micro tension condition under the
blade. Similarly, decreasing the depth into the web decreases the
micro tension under the blade. The lower the durometer of the
entrance pull stand roll and rubber roll of the exit pull stand,
the larger the footprint or contact area between the rolls. A
larger footprint produces more surface friction, thereby limiting
web slippage and increasing tension. Likewise, web slippage can be
effected by changing the surface texture of the rolls, i.e., a
smooth roll will allow greater slippage than a highly contrasting
or rough surface texture. Increasing friction, as the fabric passes
under the blade(s), also produces tension. Friction is a function
of the surface area of the bottom of the blade(s). Increasing the
surface area increases the friction which increases the
tension.
[0065] The entry angle of the web into the blade(s) can be varied
by blade roll height, blade roll diameter, blade angle, distance
between prior blade roll(s) and blade(s), and height of the blades.
Increasing the blade roll height and blade roll diameter increases
the entry angle into the blade. Rotating the blade angle clockwise
from the perpendicular, with the web running left to right,
increases the entry angle. Likewise, rotating the blade angle
counter-clockwise from the perpendicular, with the web running left
to right, decreases the entry angle. Decreasing the distance
between the roll before the blade and the blade decreases the angle
of entry. Increasing the downward depth of the blade(s) into the
web decreases the angle of entry into the blade(s).
[0066] The angle of the blade(s) is completely changeable and fully
rotational to 360.degree.. The fully rotational axis provides an
opportunity for more than one blade per rotational axis. Therefore,
a second blade having a different thickness, bevel, shape,
resonance, texture, or material can be mounted. Ideally the
apparatus contains two or three blades per blade mount.
[0067] The blade height or blade pressure applied against a web can
be obtained through the vertical positioning of the blade(s) in the
blade mount. The greater the downward depth of the blade(s), the
greater the pressure. Blade pressure against the web is also
accomplished through the tension of the web as described above.
[0068] The same line components that affect the entry angle of the
web into the blade(s), also affect the exit angle of the web out of
the blade. Any changes in blade roll(s) vertical height, diameter,
or distance away from the blade, affects the exit angle of the web.
If the angle of the blade is rotated clockwise as described above,
the entry angle of the web increases, thus decreasing the exit
angle.
[0069] Web speed is proportional to the variable speed of the motor
which drives the entrance and exit nip stands. Web speed can effect
the physics of the polymers as the web passes under the blades.
[0070] The number of blades can vary. Generally, more than one
blade is required. The polymer is first applied onto the web prior
to the first blade. At this blade, a rolling bead of polymer can
exist at the interface of the blade and the web (entry angle)
Basically, a high viscosity polymer is applied and through the
process of shear thinning, the viscosity is greatly decreased,
allowing the polymer to enter into the interstitial spaces of the
web. Any blade(s) after the first blade, serves to further control
the polymer rheology and viscosity and continue the controlled
placement of the polymer into the web. This is accomplished by
controllably removing excess polymer to obtain an even distribution
of polymer to any area, or a combination of the three areas of a)
the thin film encapsulation of the individual fibers and filaments,
b) the controlled placement of the internal layer, and c) the
controlled placement of the additives in a) and b).
[0071] The initial process dynamics for the rheology and viscosity
of the polymer is designed and engineered with the required
attributes to achieve (a) the thin film encapsulation of the
individual fibers and filaments, (b) the controlled placement of
the internal layer, and (c) the controlled placement of the
additives in (a) and (b). If the polymer viscosity is high, the
polymer may need to be pre-thinned by using a dynamic mixer or
three-roll head, as shown in FIG. 12a. The dynamic mixer or the
three-roll head can significantly reduce the viscosity and even
pre-place the polymer into a thick substrate or web to allow the
blades to further shear thin and enhance the flow and placement of
the polymer.
[0072] The entrance pull stand is a driven roll proportionally
driven at a predetermined rate slower than the exit pull stand. The
entrance and exit pull stands are adjustable from about 100 pounds
of force to 5 or more tons of force.
[0073] The bottom rolls of both the entrance and exit pull stands
have micro-positioning capability to provide for gap adjustment and
alignment. The composition of the top roll of the entrance and exit
pull stands is chosen based on the durometer of the urethane or
rubber. The top roll of the exit pull stand preferably utilizes a
Teflon sleeve which will not react with the polymers used in the
process. The bottom roll of the exit pull stand is preferably
chrome plated or highly polished steel to reduce the impression
into the preplaced polymer in the web.
[0074] If desired, non-contact antistatic devices may be installed
in locations where noticeable levels of static buildup are
detected. However, there is no evidence of adverse effects due to
static buildup in the process.
[0075] Blade thickness and shape have substantial effects on the
movement of the structural elements of the web during processing
and more importantly, the viscoelastic flow characteristics of the
polymer in controlling (a) the thin film encapsulation of the
individual fibers and filaments, (b) the controlled placement of
the internal coating, and (c) the controlled placement of the
additives in (a) and (b). The blade bevel can effect the entry
angle of the web and effect the sharpness of the leading edge of
the blade. A sharper leading edge has a greater ability to push the
weave or structural elements of the web longitudinally and
traversely, increasing the size of the interstitial spaces. As the
web passes the leading edge of the blade, the interstitial spaces
snap back or contract to their original size. The polymer viscosity
is reduced and the polymer is placed into the web at the leading
edge of the blade. Blade thickness and shape effects the polymers
and their selected additives and the placement thereof. Preferably,
the combination of the leading edge condition and the two surfaces
(the front and the bottom) that meet at the leading edge are RMS 8
or better in grind and/or polish. This creates a precise leading
edge; the more precise the leading edge, the more the shear
thinning control.
[0076] There are a number of pre-qualifiers or engineered
attributes of polymers that enhance control of flow and polymer
placement in:(a) the thin film encapsulation of the individual
fibers and filaments, (b) the controlled placement of the internal
coating, and (c) the controlled placement of the additives in (a)
and (b). Blending polymers is one way to achieve ideal flow and
placement characteristics. An example of a blended polymer is where
one polymer, selected for its physical properties, is mixed with
another polymer that is selected for its viscosity altering
properties. Many tests using different polymer blends have been
done. Polymer blends vary by both chemical and physical adhesion,
durability, cure dwell time required, cure temperature required,
flexibility, percentage add-on required, performance requirements,
and aesthetics.
[0077] Accelerators and inhibitors which are added to polymers,
generally produce three effects. An illustrative accelerator or
inhibitor is a platinum catalyst, which is a cure or crosslinking
enhancer. The first effect it produces is to control the time and
temperature of the web as it cures. A cure or controlled
crosslinking enhancer can significantly assist in controlling the
drape and hand feel of the web. The second effect is to to alter
the cure to allow the web to reach partial cure and continue curing
after leaving an initial heat zone. This second effect also assists
in retaining the drape and hand feel of the web. The third effect
of inhibitors is to achieve a semi-cure for later staging of the
cure.
[0078] Additives which are added to the polymers significantly
control surface chemistry. Surface chemistry characteristics are
controlled by including additives that have both reactive and
bio-interactive capabilities. The method and apparatus of this
invention can control the placement of the additives on the surface
of the thin film encapsulating the fibers, on either or both
surfaces of the internal layer, on either or both surfaces of the
web, or any combination of the foregoing.
[0079] The oven cure temperature and the source and type of cure
energy, are controlled for a number of reasons. The oven cure
temperature is controlled to achieve the desired crosslinked state;
either partial or full. The source and type of energy can also
affect the placement of the polymer and additives. For example, by
using a high degree of specific infrared and some convection heat
energy for cure, some additives can be staged to migrate and/or
bloom to the polymer surfaces.
[0080] Oven cure temperature is thermostatically controlled to a
predetermined temperature for the web and polymers used. Machine
runs of new webs are first tested with hand pulls to determine
adhesion, cure temperature, potentials of performance values,
drapability, aesthetics, etc. The effect on the web depends on the
oven temperature, dwell time and curing rate of the polymer. Webs
may expand slightly from the heat.
[0081] Oven cure dwell time is the duration of the web in the oven.
Oven cure dwell time is determined by the speed of the oven's
conveyor and physical length of the oven. If the dwell time and
temperature for a particular web is at maximum, then the oven
conveyor speed would dictate the speed of the entire process line
or the length of the oven would have to be extended in order to
increase the dwell time to assure proper final curing of the
web.
[0082] The physical construction and chemistry of the web is
critical. The amount of control over the rheology of the polymer
and the tension on the web are dependent on the physical
construction and chemistry. The web selected must have physical
characteristics that are compatible with the flow characteristics
of the polymer.
[0083] The ambient polymer temperature refers to the starting or
first staging point to controlling the viscosity and rheology. The
process head can control the ambient polymer temperature through
temperature controlled polymer delivery and controlled blade
temperatures.
[0084] Humidity can sometimes inhibit or accelerate curing of the
polymer. Therefore, humidity needs to be monitored and, in some
conditions, controlled.
[0085] The degree the web is deformed under lateral tension is
controllable by the choice of the physical construct of the web,
the blade angle, the blade leading edge condition, and the micro
and macro tension of the web.
[0086] Airborne contaminants and lint on the web can affect
primability and can create pin holes in the polymer. Therefore,
airborne contaminants and lint on the web need to be controlled to
reduce or eliminate pin holes or uncontrolled primability.
[0087] In view of the fact that between the shear thinning stations
and the oven, the polymer composition may begin to set or partially
cure, it may be desirable to overshear so that by the time the web
gets to the curing oven, it will be at the point where it is
desired that the cure occur. This over shear effect is a matter of
controlling certain variables, including the force of the blades
against the moving web, as well as the tension and speed of the
web.
[0088] By having a number of shear thinning blades, you create a
multiple shear thinning effect, which changes the final construct
of the polymer and the (a) thin film encapsulation of the
individual fibers and filaments, (b) controlled placement of the
internal coating, and (c) controlled placement of the additives in
(a) and (b). It is understood that the first shear thinning causes
viscoelastic deformation of the polymer composition which, due to
its memory, tends to return to a certain level. With each multiple
shear thinning, the level to which the polymer starts at that shear
point and returns is changed. This is called thixotropic looping or
plateauing.
[0089] Definitions
[0090] The term "web" as used herein is intended to include fabrics
and refers to a sheet-like structure (woven or non-woven) comprised
of fibers or structural elements. Included with the fibers can be
non-fibrous elements, such as particulate fillers, binders, dyes,
sizes and the like in amounts that do not substantially affect the
porosity or flexibility of the web. While preferably, at least 50
weight percent of a web treated in accordance with the present
invention is fibers, more preferred webs have at least about 85
weight percent of their structure as fiber. It is presently
preferred that webs be untreated with any sizing agent, coating, or
the like, except as taught herein. The web may comprise a laminated
film or fabric and a woven or non-woven porous substrate. The web
may also be a composite film or a film laminated to a porous
substrate or a double layer.
[0091] The term "webs" includes flexible and non-flexible porous
webs. Webs usable in the practice of this invention can be
classified into two general types:
[0092] (A) Fibrous webs; and
[0093] (B) Substrates having open cells or pores, such as
foams.
[0094] A porous, flexible fibrous web is comprised of a plurality
of associated or interengaged fibers or structural elements having
interstices or intersticial spaces defined therebetween. Preferred
fibrous webs can include woven or non-woven fabrics. Other
substrates include, but are not limited to, a matrix having open
cells or pores therein such as foams or synthetic leathers.
[0095] The term "fiber", as used herein, refers to a long, pliable,
cohesive, natural or man-made (synthetic) threadlike object, such
as a monofilament, staple, filament, or the like. A fiber usable in
this invention preferably has a length at least 100 times its
diameter or width. Fibers can be regarded as being in the form of
units which can be formed by known techniques into yarns or the
like. Fibers can be formed by known techniques into woven or
non-woven webs (especially fabrics) including weaving, knitting,
braiding, felting, twisting, matting, needling, pressing, and the
like. Preferably, fibers, such as those used for spinning, as into
a yarn, or the like, have a length of at least about 5 millimeters.
Fibers such as those derived from cellulosics of the type produced
in paper manufacture can be used in combination with longer fibers
as above indicated, as those skilled in the art will readily
appreciate.
[0096] The term "filament" as used herein refers to a fiber of
indefinite length.
[0097] The term "yarn" as used herein refers to a continuous strand
comprised of a multiplicity of fibers, filaments, or the like in a
bundled form, such as may be suitable for knitting, weaving or
otherwise used to form a fabric. Yam can be made from a number of
fibers that are twisted together (spun yarn) or a number of
filaments that are laid together without twist (a zero-twist
yarn).
[0098] A flexible porous web used as a starting material in the
present invention is generally and typically, essentially planar or
flat and has generally opposed, parallel facing surfaces. Such a
web is a three-dimensional structure comprised of a plurality of
fibers with interstices therebetween or a matrix having open cells
or pores therein. The matrix can be comprised of polymeric solids
including fibrous and non-fibrous elements.
[0099] Non-fibrous elements, such as particulate fillers, binders,
dyes, sizes and the like can be added to fibers in a web. Preferred
webs have at least about 85% of their structure comprised of
fibrous or fiber materials and are untreated with any sizing agent,
coating, or the like.
[0100] Two principal classes of substrates having open pores or
cells may be utilized in the present invention: leathers (including
natural leathers, and man-made or synthetic leathers), and foamed
plastic sheets (or films) having open cells.
[0101] Foamed plastic sheet or film substrates are produced either
by compounding a foaming agent additive with resin or by injecting
air or a volatile fluid into the still liquid polymer while it is
being processed into a sheet or film. A foamed substrate has an
internal structure characterized by a network of gas spaces, or
cells, that make such foamed substrate less dense than the solid
polymer. The foamed sheets or film substrates used as starting
materials in the practice of this invention are flexible,
open-celled structures.
[0102] Natural leathers suitable for use in this invention are
typically split hides. Synthetic leathers have wide variations in
composition (or structure) and properties, but they look like
leather in the goods in which they are used. For purposes of
technological description, synthetic leathers can be divided into
two general categories: coated fabrics and poromerics.
[0103] Synthetic leathers which are poromerics are manufactured so
as to resemble leather closely in breathability and moisture vapor
permeability, as well as in workability, machinability, and other
properties. The barrier and permeability properties normally are
obtained by manufacturing a controlled microporous (open celled)
structure.
[0104] Synthetic leathers which are coated fabrics, like
poromerics, have a balance of physical properties and economic
considerations. Usually the coating is either vinyl or urethane.
Vinyl coatings can be either solid or expanded vinyl which has
internal air bubbles which are usually a closed-cell type of foam.
Because such structures usually have a non-porous exterior or front
surface or face, such structures display poor breathability and
moisture vapor transmission. However, since the interior or back
surface or face is porous, such a coated fabric can be used in the
practice of this invention by applying the polymer to the back
face.
[0105] The fibers utilized in a porous flexible web treated by the
methods and apparatus of the present invention can be of natural or
synthetic origin. Mixtures of natural fibers and synthetic fibers
can also be used. Examples of natural fibers include cotton, wool,
silk, jute, linen, and the like. Examples of synthetic fibers
include rayon, acetate, polyesters (including
polyethyleneterephthalate), polyamides (including nylon), acrylics,
olefins, aramids, azlons, glasses, modacrylics, novoloids, nytrils,
rayons, sarans, spandex, vinal, vinyon, regenerated cellulose,
cellulose acetates, and the like. Blends of natural and synthetic
fibers can also be used.
[0106] With respect to the fluorochemical liquid dispersions (or
solutions) which can optionally be used for web pretreatment, the
term "impregnation" refers to the penetration of such dispersions
into a porous web, and to the distribution of such dispersions in a
preferably, substantially uniform and controlled manner in such
web, particularly as regards the surface portions of the individual
web component structural elements and fibers.
[0107] With respect to the polymer compositions used in this
invention, the term "controlled placement" or "placement" refers to
the penetration of such polymer compositions into a porous web, to
the distribution of such composition in a controlled manner through
such web, and to the resultant, at least partial envelopment of at
least a portion of the fibers of such web by such composition in
accordance with the present invention, or to the formation of an
internal layer, or both.
[0108] The word "thixotropy" refers herein to liquid flow behavior
in which the viscosity of a liquid is reduced by shear agitation or
stirring. It is theorized to be caused by the breakdown of some
loosely knit structure in the starting liquid that is built up
during a period of rest (storage) and that is torn down during a
period of suitable applied stress.
[0109] The term "coating" as used herein, refers to a generally
continuous film or layer formed by a material over or on a
surface.
[0110] The term "internal coating or internal layer" as used
herein, refers to a region spaced from the outer surfaces of the
web which is substantially continuously filled by the combination
of the polymer controllably placed therein and the fibers and
filaments of the web in the specified region. Such coating or layer
envelopes, and/or surrounds, and/or encapsulates individual fibers,
or lines cell or pore walls of the porous web or substrate, in the
specified region. The internal layer is not necessarily flat but
may undulate or meander through the web, occasionally even touching
one or both surfaces of the web.
[0111] The term "envelop" or "encapsulate" as used interchangeably
herein, refers to the partial or complete surrounding, encasement,
or enclosing by a discrete layer, film, coating, or the like, of
exposed surface portions of at least some individual fiber or
lining of a cell or pore wall of a porous web. Such a layer can
sometimes be contiguous or integral with other portions of the same
enveloping material which becomes deposited on internal areas of a
web which are adjacent to such enveloping layer, enveloped fiber,
lined cell or pore wall, or the like.
[0112] The term "elastomeric" as used herein refers to the ability
of a cured polymer treated web to stretch and return to its
original state.
[0113] The term "curing", or "cure", as used herein, refers to a
change in state, condition, and/or structure in a material, such as
a curable polymer composition that is usually, but not necessarily,
induced by at least one applied variable, such as time,
temperature, radiation, presence and quantity in such material of a
curing catalyst or curing accelerator, or the like. The term
"curing" or "cured" covers partial as well as complete curing. In
the occurrence of curing in any case, such as the curing of such a
polymer composition that has been selectively placed into a porous
flexible substrate or web, the components of such a composition may
experience occurrence of one or more of complete or partial (a)
polymerization, (b) cross-linking, or (c) other reaction, depending
upon the nature of the composition being cured, application
variables, and presumably other factors. It is to be understood
that the present invention includes polymers that are not cured
after application or are only partially cured after
application.
[0114] The term "filled" as used herein in relation to interstices,
or intersticial spaces, or open cells, and to the amount of polymer
composition therein in a given web, substrate, or the fibers in
such web or substrate, designates the presence of such composition
therein. When a given intersticial space or open cell is totally
taken up by such composition, it is "completely filled" or
"plugged". The term "filled" also refers to an intersticial space
having a film or layer of polymer composition over or through it so
that it is closed even though the entire thickness of the
interstitial space is not completely filled or plugged.
[0115] Measurements of the degree of envelopment, interstitial
fillage, plugging, or the like in an internal coating are
conveniently made by microscopy, or preferably by conventional
scanning electron microscopy (SEM) techniques. Because of the
nature of such measuring by SEM for purposes of the present
invention, "a completely filled" intersitial space or open cell can
be regarded as a "plugged" interstitial space or open cell.
[0116] The term "polymer", or "polymeric" as used herein, refers to
monomers and oligomers as well as polymers and polymeric
compositions, and mixtures thereof, to the extent that such
compositions and mixtures are curable and shear thinnable.
[0117] The term "shear thinning" in its broadest sense, means the
lowering of the viscosity of a material by the application of
energy thereto.
[0118] A porous web or fabric is preferably untreated or scoured
before being treated in accordance with the present invention.
Preferably a web can be preliminarily treated, preferably
saturated, for example, by padding, to substantially uniformly
impregnate the web with a fluorochemical. Typically, and
preferably, the treating composition comprises a dispersion of
fluorochemical in a liquid carrier. The liquid carrier is
preferably aqueous and can be driven off with heat after
application. The treating composition has a low viscosity,
typically comparable to the viscosity of water or less. After such
a treatment, it is presently preferred that the resulting treated
web exhibits a contact angle with water measured on an outer
surface of the treated web that is greater than about 90 degrees.
The treated web preferably contains fluorochemical substantially
uniformly distributed therethrough. Thus, the fluorochemical is
believed to be located primarily on and in the individual fibers,
cells or pores with the web interstices or open cells being
substantially free of fluorochemical.
[0119] A presently preferred concentration of fluorochemical in a
treatment composition is typically in the range of about 1 to about
10% fluorochemical by weight of the total treating composition
weight, and more preferably is about 2.5% of an aqueous treating
dispersion. Web weight add-ons of the fluorochemical can vary
depending upon such factors as the particular web treated, the
polymer composition to be utilized in the next step of the
treatment process of this invention, the ultimate intended use and
properties of the treated web of this invention, and the like. The
fluorochemical weight add-on is typically in the range of about
0.01 to about 5% of the weight of the untreated web. After
fluorochemical controlled placement, the web is preferably squeezed
to remove excess fluorochemical composition after which the web is
heated or otherwise dried to evaporate carrier liquid and thereby
also accomplish fluorochemical insolubilization or sintering, if
permitted or possible with the particular composition used.
[0120] The fluorochemical treated web thereafter has a
predetermined amount of a curable polymer composition controllably
placed within the web by the methods and apparatus of this
invention, to form a web whose fibers, cells or pores are at least
partially enveloped or lined with the curable polymer composition,
whose web outer surfaces are substantially free of the curable
polymer, whose web interstices or open cells are not completely
filled with the curable polymer and which may also contain an
internal layer of polymer. The curable polymer composition utilized
preferably exhibits a viscosity greater than 1,000 centipoise and
less than 2,000,000 centipoise at rest at 25.degree. C. at a shear
rate of 10 reciprocal seconds.
[0121] The fluorochemical residue that remains after web treatment
may not be exactly evenly distributed throughout the web, but may
be present in the web in certain discontinuities. For example,
these discontinuities may be randomly distributed in small areas
upon an individual fiber's surface. However, the quantity and
distribution of fluorochemical through a web is believed to be
largely controllable. Some portions of the fluorochemical may
become dislodged from the web and migrate through the polymer due
to the forces incurred by the shear thinning and controlled
placement of the polymer.
[0122] The curable polymer composition is believed to be typically
polymeric, (usually a mixture of co-curable polymers and
oligomers), and to include a catalyst to promote the cure. The
polymers that can be used in the present invention may be monomers
or partially polymerized polymers commonly known as oligomers, or
completely polymerized polymers. The polymer may be curable,
partially curable or not curable depending upon the desired
physical characteristics of the final product. The polymer
composition can include conventional additives.
[0123] While silicone is a preferred composition, other polymer
compositions can include, polyurethanes, fluorosilicones,
silicone-modified polyurethanes, acrylics,
polytetrafluoroethylene-contai- ning materials, and the like,
either alone or in combination with silicones.
[0124] It is to be understood that the depth of polymer placement
into a web can be controlled by the methods and apparatus herein
described to provide selective placement of the polymer within the
substrate or web. The web is thereafter optionally cured to convert
the curable composition into a solid elastomeric polymer.
[0125] The polymer composition is theorized to be caused to flow
and distribute itself over fibers, cells or pores in a web under
the influence of the processing conditions and apparatus provided
by this invention. This flow and distribution is further theorized
to be facilitated and promoted by the presence of a fluorochemical
which has been preliminarily impregnated into a web, as taught
herein. The amount of fluorochemical or fluorochemical residue in a
web is believed to influence the amount, and the locations, where
the polymer will collect and deposit, and produce encapsulated
fibers and/or an internal layer in the web. However, there is no
intent to be bound herein by theory.
[0126] Some portion of the residue of fluorochemical resulting from
a preliminary web saturating operation is theorized to be present
upon a treated fiber's surfaces after envelopment of fibers, cells
or pores by the polymer has been achieved during the formation of
the encapsulating fiber and/or the internal layer by the practice
of this invention. This is believed to be demonstrated by the fact
that a web treated by this invention still exhibits an enhanced
water and oil repellency, such as is typical of fluorochemicals in
porous webs. It is therefore believed that the fluorochemicals are
affecting the adherence of the polymer as a thin film enveloping
layer about the treated fibers, cells or pores as well as
facilitating polymer pressurized flow within and about the
interstices or open cells of the web being treated so that the
polymer can assume its position enveloping the fibers or lining the
cells or pores of the substrate.
[0127] In those fabrics that are pretreated with fluorochemicals,
the exact interrelationship between the polymer film and the
impregnated fluorochemical is presently difficult, or perhaps
impossible, to quantify because of the variables involved and
because transparent polymer is difficult to observe by optical
microscopy. It can be theorized that perhaps the polymer and the
fluorochemical each tend to produce discontinuous films upon the
fiber surface, and that such films are discontinuous in a
complementary manner. It may alternatively be theorized that
perhaps the polymer film is contiguous, or substantially so,
relative to fluorochemical molecules on a fiber surface, and that
the layer of polymer on a fiber surface is so thin that any
dislodgement of the fluorochemical may release the fluorochemical
into the polymer film thereby allowing the fluorine to orient or
project through the film with the required cure temperature of the
polymer, reactivating the water surface contact angle so that the
water repellent properties of the fluorochemical affect the
finished product. However, regardless of physical or chemical
explanation, the combination of polymer film and fluorochemical
results in a fiber envelopment or cell or pore wall lining and the
formation of encapsulated fibers and/or an internal layer of
polymer in a web when this invention is practiced. After curing,
the polymer is permanently fixed material.
[0128] By using the methods and apparatus of this invention, one
can achieve a controlled placement of a polymer composition into a
porous substrate or web to obtain a desired treated web.
[0129] A curable polymer such as used in the practice of this
invention is applied under pressure using shear forces onto and
into a web or substrate. The shear forces cause the curable
silicone polymer to flow into the web. The extent of fiber
envelopment and cell or pore wall lining is believed to be
regulatable by controlling such factors as discussed previously, as
well as the selection and applied amount of fluorochemical, if any,
the curable polymer used, and the applied compressive and shear
forces employed at a given temperature so that fiber envelopment is
achieved while the interstices and/or open cells of the web are not
completely filled with such polymer in the region of the internal
layer, and the outer opposed surfaces of the web are substantially
completely free of polymer coating or residue. After such a
procedure, the curable polymer is then cured.
[0130] The curable polymer is applied onto the surface of the web.
Then, the web, while tensioned, is passed over and against shearing
means or through a compression zone, such as between rollers or
against a shear knife. Thus, transversely applied shear force and
compressive pressure is applied to the web. The combination of
tension, shearing forces, and web speed is sufficient to cause the
polymer to move into the web and out from the interstices or open
cells around the web fibers, cells, or pores being enveloped. The
result is that at least some of the interstices and/or open cells
are unfilled in regions of the web outside of the region occupied
by the internal coating or internal layer, and are preferably
substantially free of polymer. Excess polymer is removed by the
surface wiping action of the shearing means. The curable polymer
enveloping the fibers is thereafter cured.
[0131] The desired penetration of, and distribution and placement
of polymer in, a web is believed to be achieved by localized
pressuring forces exerted on a web surface which are sufficiently
high to cause the viscosity of a polymer composition to be locally
reduced, thereby permitting such polymer to flow under such
pressuring and to be controllably placed within the web and to
envelope its fibers or line the cell or pore walls thereof. To aid
in this process, the web is preferably at least slightly distorted
by tensioning or stretching, while being somewhat transversely
compressed at the location of the controlled placement. This
distortion is believed to facilitate the entrance of the polymer
composition into the web. When the compression and tension are
released, the polymer composition is believed to be squeezed or
compressed within and through the interstitial spaces, or open cell
spaces, of the treated web.
[0132] If, for example, too much polymer is present in the finished
product, then either or both the tension and shear force can be
increased, and vice versa for too little polymer. If flow is not
adequate upon the fibers, producing incomplete fiber envelopment,
then the viscosity of the polymer composition can be reduced by
increasing the pressures and temperatures employed for the
controlled placement thereof. Alternatively, if the viscosity is
too low, then the pressure and/or temperature can be decreased. If
the polymer composition is resistant to being positioned or placed
in a desired location in a desired amount in a given web at various
viscosities and/or pressures, then the level of fluorochemical
pretreatment of the web can be increased, or decreased, as the case
may be.
[0133] In one embodiment of this invention, polymer is forced into
a web between two rollers. One such roller bears a polymer
impregnant, typically and preferably distributed uniformly upon and
over a circumferentially extending textured, or gravure surface.
Such roller rotates (i) in the same direction as a facing roller
and (ii) oppositely to the direction of movement of a continuously
moving web traveling past the localized pressured area achieved
between such roller and such moving web. The unidirectional
rotation of the two rollers is believed to produce a distorting and
stretching force or effect upon the web. This force is believed to
promote penetration of the polymer into the web. This form of
pressured application or coating can be termed "reverse roll
coating" for convenience. Preferably, the reverse coating rollers
have generally horizontal axis while the moving web moves generally
horizontally. The web is further concurrently both longitudinally
tensioned and distorted by being stretched against metering bars,
bar knives, and the like which are urged against the web.
[0134] Such an initial pressured step is preferably followed by a
series of further pressured web treatment steps believed to
accomplish polymer reintroduction, polymer distribution, polymer
scraping, and excess polymer removal and recovery. The collective
result of such steps gradually produces a web wherein the polymer
envelopes to a desired extent the fibers, or lines the cell or pore
walls comprising the web and collects within a desired internal
region or zone in the web thereby filling or plugging interstitial
spaces, or open cells or pores, of the web in such region, but not
filling the internal structure of the treated web with polymer
beyond a desired extent. Particularly, and for example, in a
fabric, a polymer composition may be made to substantially
completely envelope the fibers or line the cells or pores thereof
and fill the interstitial spaces thereof in such internal
region.
[0135] In another embodiment of this invention, application of
polymer to a web occurs from a reservoir. This reservoir of polymer
is positioned tightly against the tensioned, moving web (or
fabric). The linearly extending, preferably vertically upwardly
moving, web (or fabric), constitutes a wall portion of the
reservoir. Next, along the path of web travel, a bar or shear knife
is pressed strongly and transversely against and laterally across
the longitudinally tensioned web (or fabric). Further along the
path of web movement, a shear blade or flexible scraper knife is
also strongly and transversely forced laterally across and against
the tensioned web. More than one shear knife, or more than one
flexible compressive knife, can be successively positioned along
the path of web movement. These blade means are believed to
reintroduce the polymer into the web, to distribute the polymer,
and to promote and complete the envelopment of fibers or lining of
the cell or pore walls and fillage of interstices and open cells
with polymer, and form an internal coating in a desired region in a
web or encapsulate the fibers, or both. These scraper knives or
shear blades are also believed to force the polymer further into
the three-dimensional structure of the web. Also, these knives,
particularly the scraper knives, wipe or scrape excess polymer off
the surface of the web, and also extract polymer from within the
web, thereby regulating the amount of polymer placed within the
web.
[0136] The transversely applied shear forces applied across and
against the web are sufficiently high to achieve temporarily and
locally, a lowering of the viscosity of the preferably thixotropic
viscous polymer. The lowered viscosity polymer is thus enabled to
flow into, and upon, the internal three-dimensional structure of
the web. Because the polymer composition that is being applied is
subject to cure with heat or radiation and time, and because the
pressured placement or shear thinning is believed to produce
localized heat, the shearing conditions used prior to curing are
preferably controlled to minimize premature curing. The properties
of the polymer are preferably selected to be such that cure, or
excessive cure, does not occur while the web is being treated with
polymer during the shear thinning and controlled placement. The
cure preferably occurs only after the web controlled placement
procedure has been completed. Preferably, the cure temperature of
the polymer composition is relatively high (preferably above about
250.degree. F.) and the heat exposure time is such as is needed to
obtain a desired solid resilient elastomeric polymer.
[0137] The viscosity of the polymer is preferably lowered by the
high pressure (shear) forces exerted. However, such a pressure-
and/or temperature-induced lowered viscosity should not go down too
low, otherwise the polymer can flow substantially uncontrolled in
the web in the manner of a low viscosity liquid that is saturated
and impregnated into a web as in prior art web treatments. If the
viscosity of the polymer composition is too low at the time of
controlled placement then the web interstices or open cells can
become excessively filled therewith, and the polymer is not, for
example, reliably and controllably applied to achieve an
envelopment of the structural elements (including fibers) of the
web being treated together with internal coating formation.
[0138] Benzophenones, and particularly 2,4-dihydroxybenzophenone,
are believed to be a particularly useful class of additives to the
starting polymer composition, as hereinbelow described.
[0139] As indicated above, the activity transpiring at a final step
in the practice of this invention is generically referred to as
curing. Conventional curing conditions known in the prior art for
curing polymer compositions are generally suitable for use in the
practice of this invention. Thus, temperatures in the range of
about 250.degree. F. to about 350.degree. F. are used and times in
the range of about 30 seconds to about 1 minute can be used,
although longer and shorter curing times and temperatures may be
used, if desired, when thermal curing is practiced. Radiation
curing, as with an electron beam or ultraviolet light can also be
used. However, using platinum catalysts to accelerate the cure
while using lower temperatures and shorter cure times is
preferable.
[0140] Since either filled, plugged, almost filled interstices, or
open cells in the region of an internal layer remain transmissive
of air in cured webs made by this invention, the webs are
characteristically air permeable or breathable.
[0141] Sample webs or fabrics that are beneficially treated, fiber
enveloped and internally coated in accordance with the invention
include nylon, cotton, rayon and acrylic fabrics, as well as
fabrics that are blends of fiber types. Sample nylon fabrics
include lime ice, hot coral, raspberry pulp, and diva blue
Tactel.RTM. (registered trademark of ICI Americas, Inc.) fabrics
available from agent Arthur Kahn, Inc. Sample cotton fabrics
include Intrepid.RTM. cotton cornsilk, sagebrush cotton, and light
blue cotton fabrics available also from Arthur Kahn, Inc.
Non-woven, monofilamentous, fabrics such as TYVEK.RTM. (registered
trademark of E.I. duPont de Nemours Co., Inc.) and the like are
also employable.
[0142] As indicated above, a web is preferably pretreated and
impregnated with a fluorochemical prior to being treated with a
polymer composition as taught herein. The fluorochemical
impregnation is preferably accomplished by first saturating a web
with a liquid composition which incorporates the fluorochemical,
and then, thereafter, removing the excess liquid composition and
residual carrier fluid by draining, compression, drying, or some
combination thereof from the treated web.
[0143] It is now believed that any fluorochemical known in the art
for use in web, particularly fabric treatment in order to achieve
water repellency, soil repellency, grease repellency, or the like,
can be used for purposes of practicing the present invention. It is
believed that a typical fluorochemical of the type used for web
treatment can be characterized as a compound having one or more
highly fluorinated portions, each portion being a fluoroaliphatic
radical or the like, that is (or are) functionally associated with
at least one generally non-fluorinated organic portion. Such
organic portion can be part of a polymer, part of a reactive
monomer, a moiety with a reactable site adapted to react with a
binder, or the like. Such a compound is typically applied to a
fabric or other web as a suspension or solution in either aqueous
or non-aqueous media. Such application may be conventionally
carried out in combination with a non-fluorine or fluorine
containing resin or binder material for the purpose of providing
improved durability as regards such factors as laundering, dry
cleaning, and the like.
[0144] Fluorochemicals are sometimes known in the art as durable
water repellent (DWR) chemicals, although such materials are
typically believed to be not particularly durable and to have a
tendency to wash out from a fabric treated therewith. In contrast,
fiber enveloped webs of this invention which have been pretreated
with a fluorochemical display excellent durability and washability
characteristics. Indeed, the combination of fluorochemical
pretreatment and silicone polymer fiber envelopment such as
provided by the present invention appears to provide synergistic
property enhancement because the effects or properties obtained
appear to be better than can be obtained than by using either the
fluorochemical or the silicone polymer alone for web treatment.
[0145] Exemplary water repellent fluorochemical compositions
include the compositions sold under the name Milease.RTM. by ICI
Americas Inc. with the type designations F-14N, F-34, F-31IX, F-53.
Those compositions with the "F" prefix indicate that they contain a
fluorochemical as the principal active ingredient. More
particularly, Milease.RTM. F-14 fluorochemical, for example, is
said to contain approximately 18 percent perfluoroacrylate
copolymer, 10 percent ethylene glycol (CAS 107-21-1) and 7 percent
acetone (CAS 67-64-1) dispersed and dissolved in 65 percent water.
Milease.RTM. F-31X is said to be a dispersion of a combination of
fluorinated resin, acetone, and water.
[0146] Still another suitable class of water repellent chemicals is
the Phobotex.RTM. chemicals of Ciba/Geigy identified as
Phototex.RTM. FC104, FC461, FC731, FC208 and FC232 which are each
believed to be suitable for use, typically in approximately a 5
percent concentration, in saturating a web for use in the
invention. These and many other water repellent fluorochemicals are
believed to be capable of creating a surface contact angle with
water of greater than about 90 degrees when saturated into a web
and to be suitable for use in the practice of this invention.
[0147] Another group of useful water repellent fluorochemicals is
the TEFLON.RTM. -based soil and stain repellents of E.I. duPont de
Nemours & Co. Inc., 1007 Market Street, Wilmington, Del. 19898.
Suitable TEFLON.RTM. types for use in the practice of this
invention include TEFLON.RTM. G. NPA, SKF, UP, UPH, PPR, N. and
MLV. The active water repellent chemical of each composition is
believed to be a fluorochemical in polymeric form that is suitable
for dispersion in water, particularly in combination with a
cationic surfactant as a dispersant. These dispersions are
dilutable in all proportions with water at room temperature. One
preferred class of fluorochemical treating compositions useful in
the practice of this invention comprises about 1 to about 10 weight
percent, more preferably about 5 weight percent of one of the above
indicated TEFLON.RTM.-type water repellent fluorochemcials in
water.
[0148] Another major group of suitable water repellent
fluorochemical compositions useful in the practice of the invention
is commercially available under the designation ZEPEL.RTM. rain and
stain repellent chemicals of E.I. duPont de Nemours & Co. Inc.,
such as ZEPEL.RTM. water repellent chemicals types B. D, K, RN, RC,
OR, HT, 6700 and 7040. Each is believed to be a fluorochemical in
polymeric form that is dispersible in all proportions at room
temperature. The dispersants ZEPEL.RTM. B. D, K, and RN are
believed to be cationic, while the dispersant ZEPEL.RTM.D RC is
believed to be nonionic.
[0149] As an exemplary composition, ZEPEL.RTM. 6700 is said to be
comprised of 15 to 20 percent perfluoroalklyl acrylic copolymer, 1
to 2 percent alkoxylated carboxylic acid, and 3 to 5 percent
ethylene glycol. Exemplary characteristics of the composition
include a boiling point of 100.degree. C. at 760 mm Hg and a
specific gravity of 1.08. The volatiles are approximately 80
percent by weight. The pH is 2 to 5. The odor is mild; the
concentrate form is that of a semi-opaque liquid; and the
concentrate color is straw white. The composition and
characteristics of ZEPEL.RTM. 7040 repellent chemical are believed
to be substantially identical to those of ZEPEL.RTM. 6700 except
that the former composition additionally contains 7 to 8 percent
acetone.
[0150] Another major group of water repellent fluorochemicals
comprises the Scotchgard.RTM. water repellent chemicals of 3M Co.,
St. Paul, Minn. The Scotchgard.RTM. fluorochemicals are believed to
be aqueously dispersed fluorochemicals in polymeric form. The
compositions of two suitable Scotchgard.RTM. water repellent
fluorochemicals are believed to be disclosed in U.S. Pat. Nos.
3,393,186 and 3,356,628, which patents are incorporated herein by
reference. Thus, the Scotchgard.RTM. fluorochemical of U.S. Pat.
No. 3,356,628 consists of copolymers of perfluoroacrylates and
hydroxyalkyl acrylates. These copolymers are suitable for use as an
oil and water repellent coating on a fibrous or porous surface.
They have a carbon to carbon main chain and contain recurring
monovalent perfluorocarbon groups having from 4 to 18 carbon atoms
each and also having recurring hydroxyl radicals. From 20 to 70
percent of the weight of such copolymer is contributed by fluorine
atoms in the perfluorocarbon groups and from 0.05 to 2 percent of
the weight of the copolymer is contributed by the hydroxyl
radicals. Such copolymer is said to have improved surface
adherability properties as compared to the homopolymer of a
corresponding fluorocarbon monomer.
[0151] The Scotchgard.RTM. fluorochemical of U.S. Pat. No.
3,393,186 consists of perfluoroalkenylacrylates and polymers
thereof. An exemplary fluorinated monomer has the formula: 1
[0152] Wherein R.sub.f is a fluorocarbon group having from 3 to 18
carbon atoms, R is hydrogen or methyl, and n is 0- 16. Such a water
repellent fluorochemical composition is supplied and saturated into
the substrate web as a readily pourable aqueous dispersion.
[0153] U.S. Pat. No. 4,426,476 discloses a fluorochemical textile
treating composition containing a water-insoluble fluoroaliphatic
radical, an aliphatic chlorine-containing ester and a water
insoluble, fluoroaliphatic radical containing polymer.
[0154] U.S. Pat. No. 3,896,251 discloses a fluorochemical textile
treating composition containing a fluoroaliphatic radical
containing linear vinyl polymer having 10 to 60 weight percent
fluorine and a solvent soluble carbodiimide preferably comprising
fluoroaliphatic groups. A table in this patent lists a plurality of
prior art fluoroaliphatic radical containing polymers useful for
the treatment of fabrics and the prior art patents where such
polymers are taught.
[0155] U.S. Pat. No. 3,328,661 discloses textile treating solutions
of a copolymer of an ethylenically unsaturated fluorocarbon monomer
and a ethylenically unsaturated epoxy group containing monomer.
[0156] U.S. Pat. No. 3,398,182 discloses fluorocarbon compounds
useful for fabric treatment that contain a highly fluorinated
oleophobic and hydrophobic terminal portion and a different
nonfluorinated oleophilic portion linked together by a urethane
radical.
[0157] Water repellent fluorochemical compositions are preferably
utilized to saturate a starting untreated porous web substrate so
that such composition and its constituents wet substantially
completely and substantially uniformly all portions of the web.
Such a saturation can be accomplished by various well known
techniques, such as dipping the web into a bath of the composition,
or padding the composition onto and into the web, or the like.
Padding is the presently preferred method of fluorochemical
application.
[0158] After application of the fluorochemical composition to the
web, the water (or liquid warier) and other volatile components of
the composition are removed by conventional techniques to provide a
treated web that contains the impregnated fluorochemical throughout
the web substrate.
[0159] In a preferred procedure of fluorochemical controlled
placement, a web is substantially completely saturated with an
aqueous dispersion of a fluorochemical. Thereafter, the resulting
impregnated web is compressed to remove excess portions of said
dispersion. Finally, the web is heated to evaporate the carrier
liquid. If the fluorochemical is curable, then the heating also
accomplishes curing. After the fluorochemical treatment, the
fluorochemical is found only on or in the web structural elements
or fibers and is substantially completely absent from the web
interstices.
[0160] The fluorochemical concentration in the treating composition
is such as to permit a treated fluorochemical containing web, after
volatiles of the treating composition are removed, to exhibit a
contact angle with water applied to an outer web surface which is
greater than about 90.degree.. More preferably, the contact angle
provided is greater than about 130.degree..
[0161] The web weight add-on provided by the fluorochemical after
removal of volatiles is usually relatively minor. However, the
weight add on can vary with such factors as the nature of web
treated, the type of polymer composition utilized in the next step
of the process, the temperature at which the composition is
applied, the ultimate use contemplated for a web, and the like.
[0162] Typical weight add-ons of fluorochemical are in the range of
about 1 to about 10 percent of the original weight of the web. More
preferably, such weight add-ons are about 2 to about 4 weight
percent of the weight of the starting fabric.
[0163] Durability of a web that has been treated with a
fluorochemical and durability of a web that is subsequently treated
with a polymer can sometimes be improved by the conventional
process of "sintering". The exact physical and chemical processes
that occur during sintering are unknown. The so-called sintering
temperature utilized is a function of the fluorochemical
composition utilized and such temperature is frequently recommended
by fluorochemical manufacturers. Typically, sintering is carried
out at a temperature of about 130 to about 160.degree. C. for a
period of time of about 2 to about 5 minutes. Acid catalysts can be
added to give improved durability to laundering and dry cleaning
solvents.
[0164] The fluorochemical is believed to provide more than water or
other repellent properties to the resulting treated web,
particularly since the curable polymer is often itself a water
repellent. Rather, and without wishing to be bound by theory, it is
believed that the fluorochemical in a treated web provides relative
lubricity for the treated fibers during the pressure application of
the curable polymer. The polymer is applied under pressures which
can be relatively high, and the polymer is itself relatively
viscous, as is discussed herein. In order for the curable polymer
to coat and envelopweb fibers, but not fill web interstitial voids,
the fibers of the web may move over and against each other to a
limited extent, thereby to permit entry of the polymer into and
around the fibers. It is thought that the fluorochemical deposits
may facilitate such fiber motion and facilitate envelopment during
the pressure application and subsequent shearing processing.
[0165] Alternatively, the fluorochemical may inhibit deposition of
the polymer at the positions of the fluorochemical deposits which
somehow ultimately tends to cause thin enveloping layers of polymer
to form on fibers.
[0166] The precise physics and chemistry of the interaction between
the fluorochemical and the polymer is not understood. A simple
experiment demonstrates movement of the liquid polymer as
influenced by the presence of the fluorochemical:
[0167] A piece of fabric, for example the Red Kap Milliken poplin
polyester cotton blend fabric, is cut into swatches. One swatch is
treated with an adjuvant, for example a three percent solution of
the durable water-repellent chemical Milease.RTM. F-31X. The
treated swatch and an untreated swatch are each positioned at a
45.degree. angle to plumb. A measured amount, for example one-half
ounce, of a viscous polymer composition, for example the Mobay.RTM.
2530A/B silicon composition, is dropped onto the inclined surface
of each swatch. The distance in centimeters that the composition
flows downwards upon the surface of the swatch is measured over
time, typically for 30 minutes.
[0168] A graphical plot of the flow of the silicone composition
respectively upon the untreated and treated swatches over time can
be prepared, such as shown in FIG. 1. At the expiration of 30
minutes the viscous composition has typically traveled a distance
of about 8.8 centimeters upon the treated swatch, or a rate of
about 0.29 centimeters per minute. At the expiration of the same 30
minutes, the viscous composition has typically traveled a lesser
distance of about 7.1 centimeters upon the untreated swatch, or a
rate of about 0.24 centimeters per minute. Qualitatively
commensurate results are obtainable with other DWR fluorochemical
adjuvants that facilitate the viscous flow of polymer compositions
in accordance with the invention. Indeed, if desired, the simple
flow rate test can be used to qualify an adjuvant compound for its
employment within the method of the invention. The fluorochemical
pretreated web generally increases the surface contact angle of the
polymer while reducing the amount of saturation of the polymer into
the fibers themselves.
[0169] The fluorochemical treated web is thereafter treated under
pressure with a predetermined amount of a curable polymer
composition to form a web whose fibers are preferably substantially
completely enveloped with such curable polymer and whose outer
surfaces and interstices are preferably substantially completely
free of the curable polymer. The polymer is thereafter cured by
heat, radiation, or the like. Even room temperature curing can be
used. A polymer impregnated, fluorochemical pretreated web can be
interveningly stored before being subjected to curing conditions
depending upon the storage or shelf life of the treating silicone
polymer composition.
[0170] A curable polymer composition utilized in the practice of
this invention preferably has a viscosity that is sufficient to
achieve an internal coating of the web. Generally, the viscosity is
greater than about 1000 centipoise and less than about 2,000,000
centipoise at a shear rate of 10 reciprocal seconds. It is
presently most preferred that such composition have a viscosity in
the range of about 5,000 to about 1,000,000 centipoise at
25.degree. C. Such a composition is believed to contain less than
about 1% by weight of volatile material.
[0171] The polymer is believed to be typically polymeric and to be
commonly a mixture of co-curable polymers, oligomers, and/or
monomers. A catalyst is usually also present, and, for the
presently preferred silicone polymer compositions discussed
hereinafter, is platinum or a platinum compound, such as a platinum
salt.
[0172] A preferred class of liquid curable silicone polymer
compositions comprises a curable mixture of the following
components:
[0173] (A) at least one organo-hydrosilane polymer (including
copolymers);
[0174] (B) at least one vinyl substituted polysiloxane (including
copolymers);
[0175] (C) a platinum or platinum containing catalyst; and
[0176] (D) (optionally) fillers and additives.
[0177] Typical silicone hydrides (component A) are
polymethylhydrosiloxane- s which are dimethyl siloxane copolymers.
Typical vinyl terminated siloxanes are vinyldimethyl terminated or
vinyl substituted polydimethylsiloxanes. Typical catalyst systems
include solutions or complexes of chloroplatinic acid in alcohols,
ethers, divinylsiloxanes, and cyclic vinyl siloxanes.
[0178] The polymethylhydrosiloxanes (component A) are used in the
form of their dimethyl copolymers because their reactivity is more
controllable than that of the homopolymers and because they result
in tougher polymers with a lower cross-link density. Although the
reaction with vinyl functional silicones (component B) does
reportedly take place in 1:1 stoichiometry, the minimum ratio of
hydride (component A) to vinyl (component B) in commercial products
is reportedly about 2:1 and may be as high as 6:1. While the
hydrosilation reaction of polymethylhydrosilane is used in both so
called RTV (room temperature vulcanizable) and LTV (low temperature
vulcanizable) systems, and while both such systems are believed to
be useful in the practice of the present invention, systems which
undergo curing at elevated temperature are presently preferred.
[0179] Elastomers produced from such a curing reaction are known to
demonstrate toughness, tensile strength, and dimensional
stability.
[0180] Particulate fillers are known to be useful additives for
incorporation into liquid silicone polymer compositions. Such
fillers apparently not only can extend and reinforce the cured
compositions produced therefrom, but also can favorably influence
thixotropic behavior in such compositions. Thixotropic behavior is
presently preferred in compositions used in the practice of this
invention. A terminal silanol (Si-OH) group makes such silanol
siloxanes susceptible to reaction in curing, as is believed
desirable.
[0181] It is believed that all or a part of component B can be
replaced with a so called silanol vinyl terminated polysiloxane
while using an organotin compound as a suitable curing catalyst as
is disclosed in U.S. Pat. No. 4,162,356. However, it is presently
preferred to use vinyl substituted polysiloxanes in component
B.
[0182] A polymer composition useful in this invention can contain
curable silicone resin, curable polyurethane, curable
fluorosilicone, curable modified polyurethane silicones, curable
modified silicone polyurethanes, curable acrylics,
polytetrafluoroethylene, and the like, either alone or in
combination with one or more compositions.
[0183] One particular type of silicone composition which is
believed to be well suited for use in the controlled placement step
of the method of the invention is taught in U.S. Pat. Nos.
4,472,470 and 4,500,584 and in U.S. Pat. No. 4,666,765. The
contents of these patents are incorporated herein by reference.
Such a composition comprises in combination:
[0184] (i) a liquid vinyl chain-terminated polysiloxane having the
formula: 2
[0185] wherein R and R.sup.1 are monovalent hydrocarbon radicals
free of aliphatic unsaturation with at least 50 mole percent of the
R.sup.1 groups being methyl, and where n has a value sufficient to
provide a viscosity of about 500 centipoise to about 2,000,000
centipoise at 25.degree. C.;
[0186] (ii) a resinous organopolysiloxane copolymer comprising:
[0187] (a) (R.sup.2).sub.3SiO.sub.0 5 units and SiO.sub.2units,
or
[0188] (b) (R.sup.3).sub.2SiO.sub.0 5 units, (R.sup.3).sub.2SiO
units and SiO.sub.2 units, or
[0189] (c) mixtures thereof, where R.sup.2and R.sup.3are selected
from the group consisting of vinyl radicals and monovalent
hydrocarbon radicals free of aliphatic unsaturation, where from
about 1.5 to about 10 mole percent of the silicon atoms contain
silicon-bonded vinyl groups, where the ratio of monofunctional
units to tetrafunctional units is from about 0.5:1 to about 1:1,
and the ratios of difunctional units to tetrafunctional units
ranges up to about 0.1:1 ;]
[0190] (iii) a platinum or platinum containing catalyst; and
[0191] (iv) a liquid organohydrogenpolysiloxane having the formula:
1 ( R ) a ( H ) b SiO 4 - a - b 2
[0192] in an amount sufficient to provide from about 0.5 to about
1.0 silicon-bonded hydrogen atoms per silicon-bonded vinyl group of
above component (i) or above subcomponent (iii) of, R.sub.a is a
monovalent hydrocarbon radical free of aliphatic unsaturation, and
has a value of from about 1.0 to about 2.1, b has a value of from
about 0.1 to about 1.0, and the sum of a and b is from about 2.0 to
about 2.7, there being at least two silicon-bonded hydrogen atoms
per molecule.
[0193] Optionally, such a composition can contain a finely divided
inorganic filler (identified herein for convenience as component
(v)).
[0194] For example, such a composition can comprise on a parts by
weight basis:
[0195] (a) 100 parts of above component (i);
[0196] (b) 100-200 parts of above component (ii);
[0197] (c) a catalytically effective amount of above component
(iii), which, for present illustration purposes, can range from
about 0.01 to about 3 parts of component (iii), although larger and
smaller amounts can be employed without departing from operability
(composition curability) as those skilled in the art will
appreciate;
[0198] (d) 50-100 parts of above component (iv), although larger
and smaller amounts can be employed without departing from
operability (curability) as those skilled in the art will
appreciate; and
[0199] (e) 0-50 parts of above component (v).
[0200] Embodiments of such starting composition are believed to be
available commercially from various manufacturers under various
trademarks and trade names.
[0201] As commercially available, such a composition is commonly in
the two-package form (which are combined before use). Typically,
the component (iv) above is maintained apart from the components
(i) and (ii) to prevent possible gelation in storage before use, as
those skilled in the art appreciate. For example, one package can
comprise components (i) and (ii) which can be formulated together
with at least some of component (ii) being dissolved in the
component (i), along with component (iii) and some or all of
component (v) (if employed), while the second package can comprise
component (iv) and optionally a portion of component (v) (if
employed). By adjusting the amount of component (i) and filler
component (v) (if used) in the second package, the quantity of
catalyst component (iii) required to produce a desired curable
composition is achieved. Preferably, component (iii) and the
component (iv) are not included together in the same package. As is
taught, for example, in U.S. Pat. No. 3,436,366 (which is
incorporated herein by reference), the distribution of the
components between the two packages is preferably such that from
about 0.1 to 1 part by weight of the second package is employed per
part of the first package. For use, the two packages are merely
mixed together in suitable fashion at the point of use. Other
suitable silicone polymer compositions are disclosed in the
following U.S. patents:
[0202] U.S. Pat. No. 4,032,502 provide compositions containing a
linear polydiorganosiloxane having two siloxane bonded vinyl groups
per molecule, organosiloxane that is soluble in such linear
polydiorganosiloxane and comprised of a mixture of a
polyorganosiloxane and a polydiorganosiloxane, platinum-containing
catalyst, a platinum catalyst inhibitor, and a reinforcing silica
filler whose surface has been treated with an organosilicone
compound.
[0203] U.S. Pat. No. 4,108,825 discloses a composition comprising a
triorganosiloxy end-blocked polydiorganosiloxane, an
organohydrogensiloxane having an average of at least 2.1
silicon-bonded hydrogen atoms per molecule, a reinforcing silica
filler having a surface treated with an organosilicone compound, a
platinum catalyst, and ceric hydrate. Such silicone polymer
composition is desirable when a web is being prepared which has
flame retardant properties.
[0204] U.S. Pat. No.4,162,243 discloses a silicone composition of
100 parts by weight triorganosiloxy end-blocked
polydimethylsiloxane, reinforcing amorphous silica that is surface
treated with organosiloxane groups, organchydrogensiloxane, and
platinum catalyst.
[0205] U.S. Pat. No. 4,250,075 discloses a liquid silicone polymer
composition that comprises vinyldiorganosiloxy end-blocked
polydiorganosiloxane, polyorganohydrogensiloxane, platinum
catalyst, platinum catalyst inhibitor, and carbonaceous particles.
Such a silicone polymer composition is useful when a web of this
invention is being prepared that has electrically conductive
properties.
[0206] U.S. Pat. No. 4,427,801 discloses a curable
organopolysiloxane of liquid triorganosiloxy end-blocked
polydiorganosiloxane wherein the triorganosiloxy groups are vinyl
dimethylsiloxy or vinylmethylphenylsiloxy, finely divided amorphous
silica particles treated with mixed trimethylsiloxy groups and
vinyl-containing siloxy groups, organopolysiloxane resin containing
vinylgroups, organohydrogensiloxane, and a platinum containing
catalyst.
[0207] U.S. Pat. No. 4,500,659 discloses a silicone composition of
liquid triorganosiloxy end-blocked polydimethylsiloxane wherein the
triorganosiloxy units are dimethylvinylsiloxy or
methylphenylvinylsiloxy, a reinforcing filler whose surface has
been treated with a liquid hydroxyl end-blocked polyorganosiloxane
which is fluorine-substituted, a liquid methylhydrogensiloxane, and
a platinum-containing catalyst.
[0208] U.S. Pat. No. 4,585,830 discloses an organosiloxane
composition of a triorganosiloxy end-blocked polydiorganosiloxane
containing at least two vinyl radicals per molecule, an
organohydrogensiloxane containing at least two silicone-bonded
hydrogen atoms per molecule, a platinum-containing hydrosilation
catalyst, optionally a catalyst inhibitor, a finely divided silica
filler, and a silica treating agent which is at least partially
immiscible with said polydiorganosiloxane.
[0209] U.S. Pat. No. 4,753,978 discloses an organosiloxane
composition of a first diorganovinylsiloxy terminated
polydiorganosiloxane exhibiting a specified viscosity and having no
ethylenically unsaturated hydrocarbon radicals bonded to
non-terminal silicon atoms, a second diorganovinylsiloxy terminated
polydiorganosiloxane that is miscible with the first
polydiorganosiloxane and contains a vinyl radical, an
organohydrogensiloxane, a platinum hydrosilation catalyst, and a
treated reinforcing silica filler.
[0210] U.S. Pat. No. 4,785,047 discloses silicone elastomers having
a mixture of a liquid polydiorganosiloxane containing at least two
vinyl or other ethylenically unsaturated radicals per molecule and
a finely divided silica filler treated with a hexaorganodisilazane
which mixture is then compounded with additional
hexaorganodisiloxane.
[0211] U.S. Pat. No. 4,329,274 discloses viscous liquid silicone
polymer compositions that are believed to be suitable and which are
comprised of vinyl containing diorganopolysiloxane (corresponding
to component B), silicon hydride siloxane (corresponding to
component A) and an effective amount of a catalyst which is a
halogenated tetrameric platinum complex.
[0212] U.S. Pat. No. 4,442,060 discloses a mixture of 100 parts by
weight of a viscous diorganopolysiloxane oil, 10 to 75 parts by
weight of finely divided reinforcing silica, 1 to 20 parts by
weight of a structuring inhibitor, and 0.1 to 4 parts by weight of
2,4-dichlorobenzoyl peroxide controlled cross-linking agent.
[0213] Silicone resin compositions shown in the table below have
all been used in the practice of this invention. Such compositions
of Table I are believed to involve formulations that are of the
type hereinabove characterized.
1TABLE I Illustrative Starting Polymer Compositions MANUFACTURER
TRADE DESIGNATION COMPONENTS.sup.(1) Mobay Silopren .RTM. LSR 2530
Vinyl-terminated polydimethylsilo- xane with fumed silica,
methylhydro- gen polysiloxane Mobay Silopren .RTM. LSR 2540/01 Dow
Corning Silastic .RTM. 595 LSR Polysiloxane General Electric SLE
5100 Polysiloxane General Electric SLE 5106 Siloxane resin solution
General Electric SLE 5300 Polysiloxane General Electric SLE 5500
Polysiloxane Shin-Etsu KE 1917 Shin-Etsu DI 1940-30 SWS Silicones
Liquid Rubber BC-10 Silicone fluid with Corporation silicone
dioxide fill- er and curing agents GE SLE 5110 Polysiloxane GE SLE
6108 Polysiloxane Table I footnote: .sup.(1)Identified components
do not represent complete composition of the individual products
shown.
[0214] When a polymer composition of a silicone polymer and a
benzophenone is pressured into a porous web as taught herein,
protection of an organic web against ultraviolet radiation is
improved, and the degradation effects associated with ultraviolet
light exposure are inhibited, as may be expected from prior art
teachings concerning the behavior of benzophenones.
[0215] Surprisingly and unexpectedly, however, when silicone
polymer compositions such as used in this invention contain a
benzophenone, the resulting composition is believed to display
improved viscosity characteristics, particularly thixotropic
characteristics, and also curing acceleration, when such a
composition is subjected to high shear forces.
[0216] A presently preferred benzophenone additive useful in the
present invention is 2,4-dihydroxygenzophenone.
[0217] The regulation of internal and external rheology, and of
viscosity, achieved in a characteristically highly viscous polymer
composition of the invention is believed to be an important and
desirable feature of the benzophenone and silicone polymer
compositions which find use in internally coated web manufacture as
taught herein.
[0218] In such compositions useful in the present invention, a
control of compositional rheology, and particularly of complex
viscosity, is accomplishable, if desired, by the selective addition
of diluent and additives. These polymer compositions
characteristically exhibit performance curves indicating
substantially level and constant loss modulus, storage modulus, and
complex viscosity over extended temperature ranges. The graphic
plots of loss modulus, storage modulus, and complex viscosity
versus temperature all are believed to characteristically exhibit a
sharp knee that shows the moduli to increase in value rapidly at
cure temperatures.
[0219] Preferably, the curing proceeds to a point where the polymer
composition is no longer sticky, or tacky, but preferably curing is
not allowed to continue to a point where the resulting polymer
composition becomes excessively hard, rigid, or brittle.
Compositions of this invention are controllably curable into
polymeric materials which are preferably not sticky or tacky, and
which have desirable elastomeric, flexural, and resiliency
characteristics.
[0220] The contact angle exhibited by a silicone composition used
in this invention varies with the particular web which is to be
saturated therewith. However, the contact angle of water is
generally lower for the non-treated side than the treated side. A
combination of the processed web, the silicone polymer and the
fluorochemical generally produces higher water contact angles than
webs treated only with fluorochemicals. The performance of a
polymer composition may be determined by the nature of a previously
applied saturant such as a fluorochemical. Suitable starting
compositions include 100% liquid curable silicone rubber
compositions, such as SLE5600 A/B from General Electric, Mobay LSR
2580A/B, Dow Corning Silastic.RTM. 595 LSR and Silastic.RTM. 590
which when formulated with substituted benzophenone as taught
herein will form a contact angle of much greater than 70 degrees,
and typically of 90+ degrees, with typical porous webs (such as
fabrics) that have a residue of fluorochemical upon (and within)
the web from a prior saturation.
[0221] The polymer composition used in the practice of this
invention can also carry additives into the three-dimensional
structure of the web during the pressured application. Further, it
is preferable, that any additives be bound into the cured
composition permanently as located in the three-dimensional
structure of the web. Particularly in the case of fabrics, this
desirably positions the additives mainly on surface portions of the
encapsulated yarns and fibers in positions where they typically are
beneficially located and maintained, or on the surfaces of the
internal layer, or on the surfaces of the web, or some combination
thereof.
[0222] Control of the pressurized application step can be provided
at a number of areas since the shear process is sensitive to the
viscosity of the polymer composition both at atmospheric pressure
and at superatmospheric pressure. The ambient temperature affecting
the polymer as it is applied, and the pressure-induced temperature
changes occurring during controlled placement of the polymer also
play roles in viscosity and therefore the shear process. Of course,
the chemical composition of the polymer composition also plays a
role in the shear process and assists in the formation of an
internal layer and/or internal encapsulation of the fibers or
structural elements of the web.
[0223] The amount of polymer utilized and the weight add-on thereof
are again variable and dependent upon several things such as the
treated web, the desired end use of the web, cost and the like. Web
weight add-ons can be as little as about 5 weight percent up to
about 200 weight percent of the untreated web. For producing
breathable, water-repellent fabric webs of this invention, weight
add-ons are preferably in the range of about 10 to about 100 weight
percent of the weight of the untreated web.
[0224] The fluorochemical saturant composition may also contain a
bonding agent. The bonding agent can facilitate the bonding of the
water repellent chemical and/or the impregnate to the
three-dimensional structure of the web within which it is
saturated. Mobay Silopren.TM. bonding agent type LSR Z 3042 and
Norsil 815 primer are representative compositions that can be used
to facilitate bonding of the water repellent chemicals and/or
impregnant to and within the web. Use of the bonding agents is not
essential to the practice of this invention, but may improve
bonding of the fluorochemical and/or the polymer composition to
fibers.
[0225] The fluorochemical particularly, and also the bonding agents
when used, are preferably affixed to the three-dimensional
structure of the web prior to the controlled placement of polymer
within the web. Complete affixing is not necessary for the
fluorochemical. The fluorochemical will apparently facilitate the
pressured application of a polymer composition even if the
fluorochemical is not preliminarily fixed within or located within
the web being treated. However, fixing, especially by sintering,
appears to cause the water repellent chemicals to flow and to
become better attached to the three-dimensional structure of the
web. In this regard, a lesser amount of fluorochemical will remain
in place better, and will better facilitate the subsequent
pressured application of the polymer, if the sintering or
insolubilizing step is performed prior to such a pressured
application.
[0226] After fluorochemical saturation followed by controlled
polymer placement and curing, a web may have a surface contact
angle with the polymer of greater than about 70 degrees, and more
typically greater than about 90 degrees. Web pressures can involve
transverse force or pressure in the range of tens to thousands of
pounds per square inch of web surface.
[0227] Similar to the functional qualifications achieved by the use
of a fluorochemical in the preferred saturating pretreatment step,
the polymer introduced by the pressured application step can be
defined by its functional qualifications. For example, the silicone
polymer produces a contact angle with a fluorochemical treated web
of greater than about 70 degrees. The contact angle of a web with a
fluorochemical will be within a range of about 90 degrees to about
180 degrees while the contact angle of a fluorochemically treated
web with the silicone polymer will be within a range of about 70
degrees to about 180 degrees.
[0228] The contact angle exhibited by the silicone polymer can be,
if desired, qualified against the particular web saturated with the
particular fluorochemical saturant. The selection of a suitable
silicone polymer composition may be determined by the nature of the
previously applied fluorochemical saturant. The fluorochemical
saturant and silicone polymer compositions are, however, not
critical to the practice of this invention since wide respective
compositional ranges may be involved. In particular, a
substantially undiluted liquid silicon rubber which is available
from suppliers, such as GE, Dow Corning, and Mobay-Bayer, will
characteristically form a contact angle of much greater than about
70 degrees, and typically greater than about 90 degrees, with
typical porous webs (such as fabrics) that have a residue of
fluorochemical upon (and within) the web resulting from a prior
saturation.
[0229] The polymer composition can carry additives into the
three-dimensional structure of the web in the pressured application
steps of the method of the invention. Further, the polymer
composition, when cured, is capable of adhering to structural
elements, fibers, yarns, and the like, and any additives dispersed
therein. Thus, additives are positioned adjacent to or on surfaces
of structural elements, yarns, fibers and the like, in a position
where they can be beneficial.
[0230] Examples of additives that are dispersible in effective
amounts in a viscous polymer composition typically at a
concentration of about 0.1 to 20 weight percent (based on total
composition weight) include ultraviolet absorbers, flame
retardants, aluminum hydroxide, filling agents, blood repellents,
flattening agents, optical reflective agents, hand altering agents,
biocompatible proteins, hydrolyzed silk, and the like. Hydrolyzed
silk is a texturing agent that imparts a substantially silky feel
to a fabric treated in accordance with the method of the invention
regardless of whether or not such treated web or fabric is itself
silk.
[0231] Examples of other polymer dispersible agents include those
affecting thermal conductivity, radiation reflectivity, electrical
conductivity, and other properties. For example, if a metallic
sheen and/or thermal or electrical conductivity or infrared
background blending is desired, powdered metals may be dispersed
therein.
[0232] The pressured application of the polymer is sensitive to the
viscosity of the polymer composition. Temperature affects the
polymer composition by reducing or altering its viscosity.
Shear-induced temperature changes occurring during application or
during subsequent shear processing of the polymer can affect
viscosity. The chemical composition of the polymer also plays a
role in the treating process and effects in the treatment of web
structural elements (including fibers) and the regulation of the
filling of interstices and open cell voids.
[0233] Various machines and procedures can be used for performing
the process of the invention. Illustrative machines and processes
of use which are suitable for use in the practice of this
invention, are now described.
[0234] An embodiment of apparatus in accordance with this invention
is illustrated in the side elevational view in FIG. 4a. Two blades
200 and 210 in opposed relationship to one another are provided in
functional combination with means for providing a precisely
adjustable gap therebetween through which a web or fabric 300 is
drawn while having a polymer composition 220 applied to either one
or both surfaces thereof. An enlarged side view of a typical blade
200 or 210 is shown in FIG. 4b. Dimensions A, B,C, D, and E are
typically and exemplarily illustrated as, respectively, about 31/2
inches, about 11/2 inches, about 2 inches, about 1/2 inch, and
about 5{fraction (5/16)} inch. The narrow edge is preferably milled
to a tolerance of about {fraction (1/10,000)} inch continuously
along the edge surface of each blade which is typically and
illustratively about 38 inches long. Each of the comers of the
narrow edge is preferably and illustratively a hard (not beveled or
ground) angular edge. Each blade 200 or 210 is typically and
illustratively made from carbon steel or stainless steel. The entry
angle of the web 300 with the blade is generally not altered in the
apparatus of FIG. 4a. Therefore, for purposes of the apparatus
illustrated in FIG. 4a, the blade shown in FIG. 4b has a leading
edge 260 and a trailing edge 250.
[0235] A reservoir of polymer composition is formed preferably on
one upper surface of the web or fabric 300 behind (relative to the
direction of web movement) an upper one of the blades 200 and 210
which are mounted on a frame (not shown) so as to extend
horizontally. As the fabric 300 is drawn through the slit orifice
defined between blades 200 and 210, some polymer becomes entrained
on the web or fabric surface and moves through such slit orifice,
thereby accomplishing pressurized application of the polymer into
the web or fabric 300. The slit orifice gap is chosen preferably
and illustratively to be slightly smaller than the relaxed
thickness of the starting web or fabric.
[0236] Referring to FIG. 4a, a second pressured application station
is seen to be positioned downstream (relative to the direction of
fabric movement) from the pair of opposed blades 200 and 210. While
the blades are shown positioned directly opposed to one another,
they may be offset so that the advancing web first contacts one
blade and then the other. In such a configuration, the blades may
also be adjusted to some angle other than 90.degree. to the web,
and blade adjustment facilities (not shown) can be used to
accomplish this. At this station, a knife blade 230 is provided
which has an edge that presses against the web or fabric 300 to
reintroduce the polymer composition into the fabric 300. One side
of blade 230, adjacent to the edge thereof, is strongly biased
against an adjacent cylinder or bar 240, which, in the embodiment
shown, does not rotate. If desired, bar 240 can be journaled for
rotational movement. As the fabric is moved between the blade 230
and the bar 240, it is preferably uniformly compressed. Preferably,
the compression force is in the range of about 10 to about 500
pounds per linear inch, although higher and lower forces can be
employed. As the fabric 300 passes over the edge of blade 230, it
is drawn away at an angle from the blade edge under longitudinal
tension. For example, longitudinal tension in the range of from
about 0.5 to 10 pounds per inch can be employed. Such pressured
application or controlled placement serves to distribute and
reintroduce the polymer composition in the web. Excess polymer
composition is removed by blade scraping. Passage of the fabric 300
between the blade 230 and the bar 240 and over the edge of the
blade 230 is believed to produce shear forces in the polymer
composition 220 (within the fabric 300) that facilitate flow and
distribution thereof within the three-dimensional matrix of the
fabric 300. Concurrently, blade 230 also scrapes excess polymer
composition off the fabric's surface in contact with the edge of
blade 230.
[0237] Both the steps of fluorochemical saturation and of
subsequent polymer composition controlled placement are
performable, if desired, in production volumes, and at speeds which
can be typical of the so-called high end range of fabric finishing
lines. The fluorochemical saturation is conveniently accomplished
conventionally by using a padbath in which the fabric is run
through a dilute treating bath followed by squeeze rollers to
remove excess liquid and overdrying. In general, any method of
applying the fluorochemical would be acceptable. Typically, the web
is treated with a fluorochemical and wound on a roll before it is
introduced into apparatus of this invention apparatus although, if
desired, the fluorochemical treatment could be in-line.
[0238] Another embodiment of a machine suitable for accomplishing
controlled placement of polymer within a web in accordance with
this invention is shown diagrammatically in FIG. 5. At a treatment
or control head, pressurized introduction of the polymer
composition into the web is first carried out. At a subsequent
stage, controlled pressure reintroduction, distribution, and
metering of the polymer composition and recovery of excess polymer
transpires using a shear knife or blade which applies transverse
force against the treated web laterally across the web. In a
subsequent stage, further controlled pressure reintroduction and
metering takes place by means of another blade, either flexible or
rigid, such as, for example, a so-called flex-knife or Spanish
knife. Here, additional recovery of excess liquid polymer is
accomplished. In all knife-applying states, the excess polymer
removed is collected and preferably passed by a recycling system
back to the initial, pressured introduction stage to achieve
process operating economies. Still further successive polymer
pressure reintroduction stages may be used if desired. The
direction of the arrows in the diagrammatic representation of FIG.
5 shows the general direction of movements in the region of the
treatment head, including the general direction of polymer movement
in the practice of such process.
[0239] The apparatus employed in the present invention functions
first to apply and preferably concurrently to shear thin and place
a polymer composition into a web under pressure. Such polymer
composition is then reintroduced, distributed, and metered in a
controlled manner in the web with the aid of transversely applied
shearing force and compressive force such that the polymer
composition becomes distributed in the web so that an internal
layer of polymer is formed while the fibers are at least partially
enveloped while the interstices or open cells are substantially
completely filled with the polymer composition in the region of the
internal coating, and/or the fibers within the web are partially or
fully encapsulated. During treatment, the web is longitudinally
tensioned and the pressurized application and the subsequent
shearing and compressive actions are successively accomplished in
localized zones preferably extending generally laterally across the
web (that is, generally perpendicularly to the direction of such
longitudinal web tensioning) using transversely applied force
exerted locally against surface portions of the web during each
controlled placement and shearing operation. The web is
conveniently and preferably, but not necessarily, moved
longitudinally relative to such laterally extending web processing
zones. In treating short lengths of a fabric, the blades may be
moved relative to a stationary length of fabric. The pressurized
application, shearing and compressing steps are preferably carried
out successively or sequentially. Such zones are themselves
preferably at stationary locations while the web is moved, but if
desired, the web can be stationary while the zones are moved, or
both. The result is that the polymer composition flows into the web
and is distributed internally generally uniformly to a
predeterminable and controllable extent.
[0240] A schematic side elevational view of another embodiment of a
suitable machine for use in the practice of the invention is shown
in FIG. 6. This machine continuously moves a longitudinally
tensioned web 60 successively through a pressure station which
incorporates a reverse roll coater having rollers 10 and 11, a
shear station which incorporates a shear knife 20, and a finishing
station which employs at least one so called flex-knife (or Spanish
knife) 30. A typical shear knife is illustratively shown in FIG. 4b
for purposes of the apparatus shown in FIG. 6, the knife shown in
FIG. 4b has a leading edge 250 and a trailing edge 260. Optionally,
but preferably (for reasons of process operating economics) excess
polymer composition that is removed from web surfaces in the shear
station and finishing station is returned to the pressure station
for reuse using liquid recovery and recycle system 40. In the
pressure station, polymer 50 is contained within reservoir 51.
Roller 12 rotates in the indicated direction so that its
circumferential surface, preferably a textured or gravure surface,
picks up liquid 50 from reservoir 51 and deposits it on the
circumferential surface of roller 10 across a controlled width gap
13 between rollers 10 and 12. Typically, gap 13 is actually less
than the unencumbered thickness of the starting web 60. Roller 10
also preferably has a textured or gravure surface. Roller 10,
rotating in the roller arrow indicated direction, which is opposite
to the direction of travel of web 60, applies the polymer to one
surface of the moving web 60, which is typically a fabric. Roller
11 is urged with a compressive force against the back or opposed
surface of web 60 and roller 11 rotates in a direction which is the
same as that in which web 60 travels. Roller 11 aids in achieving
the desired pressured application of polymer into web 60 from the
surface of roller 10.
[0241] Referring to FIG. 6, the polymer is believed to be
introduced into the web and into the interstices or open cells of
the web 60 by the aid of a back-pulling or shearing action
resulting from the distorting and pressuring of web 60 caused by
rollers 10 and 11 rotating in the same direction. This direction
may be the indicated direction with roller 10 rotating against the
linear movement of web 60 indicated by web directional arrow 61, or
all rollers 10, 11 and 12 may be reversed in respective rotational
direction so as to cause each roll to turn in an opposite direction
relative to that direction which is illustrated by the respective
roller arrows in FIG. 6. Regardless of which side of web 60 is
back-pulled or subjected to shearing action by a reverse rotating
roller, the web 60 is stretched and distorted to pull open the
interstices of the web and to aid in forcing polymer 50 into the
web 60. This distorting, and particularly this stretching, is
believed to facilitate the full and deep introduction of the
polymer into the moving web 60. However, it is to be understood
that use of a reverse roll coater or other facilities which distort
the web at the polymer application stage is not required. Other
suitable polymer applicators well known in the art may be used to
deposit the polymer on the surface of the web. Thereafter, the
polymer may be shear thinned and placed into the web by use of one
or more shear knives 20.
[0242] The extent of pressured application of the polymer 50 into
the web 60 which occurs between rotating rollers 10 and 11 is
controllable to some extent by such variables as the speed of
roller rotation, the pressure exerted by rollers 10 and 11 on web
60, the durometer hardness and surface characteristics of each roll
10 and 11 (particularly of the preferred textured or gravure
surface of roll 10). However, the pressurized application may also
be carried out with rollers 10 and 11 which have finely milled,
smooth circumferential surfaces. The viscosity of polymer 50 and
the amount of polymer 50 transferred from roll 12 to roll 10 across
gap 13 may also be varied to regulate controlled placement of
polymer within the web. Feed roller 12 preferably rotates counter
to application roller 10. The polymer 50 can be monitored to assure
that its homogeneous composition is maintained. If desired, the
polymer composition 50 can be altered to adjust to process needs
during a continuous treating operation.
[0243] The result of the introduction of the polymer 50 into the
web 60 which is accomplished between rollers 10 and 11 using a
polymer composition 50, which can have the viscosity or consistency
of a conventional bathtub caulk composition, is to produce a web
60, or fabric, whose interstices or open cells are substantially
completely filled with polymer in the region of the internal layer,
or to produce a web having its structural elements or fibers
encapsulated, or to produce a web having a combination of an
internal layer and encapsulated fibers. For example, in the case of
a fabric, the region of the internal layer can be such that spaces
(i.e., interstices or open cells) between the fabric's
fibers/filaments, or the fabric's yarn members (as the case may be)
are filled with polymer 50. However, the amount of polymer 50 which
is thus introduced into web 60 can be much less than a saturation
level; for example, if desired, the amount introduced can be
insufficient even to coat or substantially completely envelope
individual fibers of the web. Actually, the polymer 50 can be
relatively non-uniformly distributed in the web after such
pressurized application. The action of the shear knife 20 in the
next zone of processing is such as to smooth out and to make
uniform the distribution of polymer 50 in web 60. Also, the shear
knife 20 helps regulate the amount of polymer 50 that is allowed to
remain in web 60. While one shear knife is shown, it may be desired
use a plurality of such knives in sequence to provide a series of
shear thinning stations.
[0244] After the shear zone, if desired, a top coat polymer can
additionally be introduced; for example, just before or after a
flex knife 30. By overcoating for example, the original polymer
with a dilute or very thin second or top coat, a more tightly cross
linked encapsulated or enveloped product may be achieved, or
surface properties of the product can be varied or improved. For
example, the top coating can comprise a dilute dispersion of a
fluorochemical fabric treating composition. In a web treated
therewith, such treatment enhances surface properties of the web,
such as by increasing grease or chemical penetration resistance, or
soil resistance, or the like. The dilute fluorochemical dispersion
can be applied by spraying, misting, or the like. Both treating
agents then enter a curing stage, which can be accomplished
conveniently by passing the treated web through an oven wherein the
temperature and web residence time are sufficient to cure both the
fluorochemical and polymer compositions to a desired extent, or by
radiation, if desired.
[0245] The amount of polymer composition actually introduced
through the controlled placement, and into the preferably stretched
openings of the interstices of the web 60 is influenced by such
factors as the velocity of movement of web 60, the viscosity
characteristics of polymer 50, the compressive pressure exerted by
roll 10 against roll 11, the longitudinal tension exerted upon the
tensioned web 60, the force of blade 20 against the web, the angle
of blade 20 relative to the web, the number of shear blades used,
the polymer distribution achieved by shear blade 20 and by scraper
flex knive(s) 30, and the like. In particular, the polymer
reintroduction and distribution believed to be achieved by bar or
shear knife 20 is achieved by the exertion of a pressure against
moving tensioned web 60. The shear force and the temperature
elevation due to such shear force results in the polymer 50 flowing
into the three-dimensional structure of the web 60.
[0246] Preferably, the polymer 50 is thixotropic. The flowing of
the polymer 50 into the web 60 using controlled liquid rheology
preferably does not result at the time of controlled placement in a
fluid viscosity which is so low as to cause the impregnant to
spread into and be distributed substantially uncontrolled
throughout the web 60. However, the flowing activity of the polymer
is preferably accomplished using a polymer 50 which has a
controllable rheology and viscosity such that a polymer 50 will
achieve a desired internal layer and/or envelopment of individual
fibers of the web 60. Particularly when the web 60 is a fabric,
this envelopment is preferably a surrounding of the fabric's
individual fibers with a localized layer or film of polymer while
an internal layer is formed.
[0247] A plurality of web tension control devices 10 can be used in
the region of metering bar or shear knife 20 and in the region of
reintroduction scraper flex knives 30 along web 60 in order to
provide the capacity for precision control of the tension exerted
on web 60 and of the compressive pressures and shear forces exerted
on web 60 at the metering bar or shear knife 20 and flexible knives
30.
[0248] As shown in FIG. 6, the machine preferably includes an
polymer 50 recovery and recycling system which more preferably also
includes a filtering subsystem, such system being diagrammatically
represented and indicated by line path 40. This system includes a
collection tray, or pan, 41, positioned under and behind the moving
web 60 to collect along the sides of web 60, the excess
impregnating liquid as it is wiped from the web surface contacted
by the shear knife 20 and/or by the recovery knives 30 and passed
laterally into pan or tray 41. From the recovery collection tray
41, the excess polymer 50 is pumped back through a filter (not
shown) into the reservoir 51 of the reverse roll coater for loading
and distribution on the surface of roller 12, transfer to roller
10, and reapplication to portions of continuously moving web 60.
The ability to reuse the excess polymer 50 wiped from the moving
web 60 rather than losing such polymer within the process makes the
entire process more economically attractive.
[0249] Another embodiment of a machine in accordance with this
invention is shown schematically in side elevation in FIG. 7. In
this embodiment, rollers 10 and 11 of the FIG. 6 methods and
apparatus are replaced with a combination of a reservoir 51, and
one or more bars or shear knives 100. A typical shear knife is
illustratively shown in FIG. 4b. For purposes of the apparatus
shown in FIG. 7, the knife shown in FIG. 4b has a leading edge 250
and a trailing edge 260. The reintroduction bar or shear knife 100
shear thins the polymer 50 which is applied or deposited onto the
moving web 60 from the reservoir 51 as a liquid or bath. The web 60
in effect constitutes a retaining wall for a part of the reservoir
51. The reservoir 51 thus functions to hold a pool of the polymer
composition 50 against a surface of the moving web 60 which in the
embodiment shown, is moving vertically upwardly. The bar or shear
knife 100 functions to apply pressure or force upon the polymer
composition polymer 50 that was deposited on the web 60, thereby to
shear thin the polymer 50 and cause it to penetrate the web 60. The
knife 100 also serves to distribute and move the polymer in the web
and to accomplish envelopment of the fibers thereof. Excess polymer
50 is also scraped away by knife 100. Optionally, one or more of
flexible or rigid knives 100 function to further reintroduce and
distribute the polymer 50 and to envelope fibers of web 60 while
forming an internal polymer layer within the web, or to produce a
web having its structural elements or fibers encapsulated, or to
produce a web having a combination of an internal layer and
encapsulated fibers. The knives 110 can be considered to function
in a manner which is equivalent to the knives 30 on the treated
surface of web 50 in the FIG. 6 methods and apparatus.
[0250] Typically, any polymer scraped from the moving web 60 by bar
knife 100 falls directly back into the reservoir 51. Polymer
scraped from the moving web 60 by scraper knife 110 is collected in
sloping trough 120 and returned by falling along the indicated
dotted line path to the reservoir 51. Longitudinal tension control
of the moving web 60 is regulated by tension control devices 70
(such as a series of rollers) from a region beginning after
reservoir 51 and extending to an oven 80 along the path of web 60
travel.
[0251] Relative to the FIG. 7 embodiment, the FIG. 6 embodiment is
believed to exhibit a wider degree of control in the practice of
the present controlled placement process. Particularly, both the
initial applied amount and the successive pressurings of, a polymer
50 are precisely controllable. Relative to the FIG. 6 embodiment,
the FIG. 7 embodiment is characterized by the capability for
operation at higher web 60 transport speeds, typically at speeds
characteristic of higher end commercial fabric finishing line
operations. The embodiment shown in FIG. 6 is believed to be
suitable for producing internally coated fabrics when the fabrics
are of the thicknesses characteristic of garments, and where deeply
controlled pressured placement over distances extending
perpendicularly into and through a web of fabric greater than about
{fraction (1/16)} inch is not generally required.
[0252] FIG. 12a depicts a schematic, side elevational view of
another method and apparatus for practicing the present invention.
In this method and apparatus, a continuous web 74 is moved along a
web pathway from a supply roll 76 to a take-up roll 77.
[0253] In a first functional processing station 78, a polymer
composition is applied to the upper face 79 of web 74 by a polymer
applicator such as a conventional reverse roll coater 81. In the
reverse roll coater 81, the polymer composition is applied to the
surface of a reversely rotating (relative to the direction of
travel of web 74) coating roll 82 from a nip region reservoir 83
formed between the coating roll 82 and a transfer roll 84 (which
rotates in the direction of travel of web 74, but whose surface
does not contact web 74). The web 74 is transversely compressed
between coating roll 82 and drive roll 86 as it passes through
station 78. Thus, the polymer composition is applied under a
positive pressure against face 79 by coating roll 82 which
functions to cause the composition to be forced into web 74. A
present preference is to use a coating roll 82 which has smooth,
chrome plated surfaces. It is also possible to apply the polymer
composition to the upper face 79 of the web 74 without any force,
leaving the controlled placement and shear thinning for a
subsequent step or series of steps, such as by the force of the
shear knives as described below.
[0254] Largely for purposes of controlling the alignment of web 74
with rolls 82 and 86, the web 74 is pretensioned by coating
clutching rolls 87, 88 and 89. After the web 74 passes over guide
roller 91 on the web pathway from supply roll 76, the web 74 passes
over roll 87, between rolls 87 and 88, around roll 88, and between
rolls 88 and 89. The clutching rolls 87, 88 and 89 are components
of a conventional web clutching mechanism (not detailed) which
provides for adjustments between rolls 87, 88 and 89 so that
selective tensioning of web 74 is achieved along the web pathway
between the clutching rolls 87, 88 and 89 and the nip region 92
defined between rolls 82 and 86 with the intervening roller roll 93
being used for guidance of web 74. The clutching rollers 87, 88 and
89 also function to smooth out and extend web 74 before it enters
the coater methods and apparatus 81 so that in the methods and
apparatus 81, the web will have polymer composition uniformly
applied thereto.
[0255] After passing nip region 92 the web 74 is controllably
longitudinally tensioned along the web pathway extending from nip
region 92 to compensating and regulating coating tension rollers
94, 95 and 96. The tension rollers 94, 95 and 96 are components of
a conventional web tension adjusting and regulating mechanism (not
detailed) which provides for on-line, in-stream operator controlled
adjustments between rollers 94, 95 and 96 that permit selective
control of the tautness of web 74 particularly in the web pathway
region from nip region 92 to rollers 94, 95 and 96. In the event a
reverse roll coater is not utilized, the tension will be controlled
in the region between rolls 87, 88 and 89 on one hand, and rolls
94, 95 and 96 on the other hand.
[0256] Along the tensioned web pathway region, the web 74
successively passes through each one or more of a series of
processing stations 98, 99 and 100. While three processing stations
are shown, more or less could be utilized in accordance with this
invention. At each of the stations 98 and 99, a substantially
non-flexible shear knife 101 and 102, respectively, extends
laterally across web 74 with the web 74 being entirely unsupported
on the lower face thereof which is opposed to upper face 79 and to
the respective blades of each shear knife 101 and 102. A typical
shear knife is illustratively shown in FIG. 4b. For purposes of the
apparatus shown in FIGS. 12a, 12b, and 12c, the knife shown in FIG.
4b has a leading edge 250 and a trailing edge 260. Both to control
the amount and type of shear force independently applied by each
knife 101 and 102 the web 74 passes over each knife edge in a
contacting relationship and three blade rolls 105, 106 and 107,
that are provided in a typically fixed (but off-line adjustable)
relationship relative to knives 101 and 102. The blades 101 and 102
are adjustable both vertically and angularly. By adjusting the
vertical height of each blade relative to the web path, the force
of each blade against the web can be controlled. By adjusting the
vertical height of the blade rolls, the shear force can be
controlled and the angle at which the web contacts the blades can
also be controlled.
[0257] Relative to the direction of web 74 travel, blade rolls 105
and 106 thus are positioned so that roll 105 is on the lead side,
and roll 106 on the trailing side, of knife 101 while blade rolls
106 and 107 are positioned so that roll 106 is on the lead side,
and roll 107 is on the trailing side of knife 102. The angle of
inclination or tilt of each blade 101 and 102 relative to the
vertical is adjustable over a wide range, but it is presently
preferred to adjust the blade inclination angle for each blade
between about .+-.45.degree. relative to the vertical with the web
74 being horizontal. In the embodiment shown, each respective blade
is functionally associated with a knife back support or holder 108
and 109, respectively. Each support 108 and 109 permits its
associated blade 101 and 102 to be vertically and angularly
positioned relative to a supporting frame (not shown).
[0258] Another adjustable variable is the amount of angular web
depression which, in the embodiment shown, extends downwardly,
achieved by the web in its passage over the circumferential edges
of adjacent rolls 105 and 106 relative to knife 101, and in its
passage over the circumferential edges of rolls 106 and 107
relative to knife 102. Considering the place where the knife 101 or
knife 102 contacts the web to be a hypothetical point, the angle of
the knife 101 or knife 102 relative to the web can be in the range
of about 30.degree. to about 140.degree..
[0259] While it is presently preferred to employ shear knives 101
and 102 which have straight edges to shear thin the polymer
composition, it will be appreciated that shear knives having
somewhat curved edges can be used, if desired. For example, when
treating a web which displays differential longitudinal stretch
characteristics laterally thereacross in response to a uniform
laterally applied warp tension, it appears to be possible to
equalize the shear forces applied to a web by employing a suitably
curved shear knife which appears to compensate for such a
differential stretch characteristic.
[0260] While it is presently preferred to employ shear knives 101
and 102 which have sharp edges, shear knives can also be used which
have dull or rounded edges. It is also preferred to use knives
having edges which are surface finished to a uniformity of at least
about root mean squared (RMS)8.
[0261] While it is presently preferred to employ shear knives 101
and 102 which are formed of steel, other materials of knife
construction could be used if desired, such as metal alloys,
non-metallic composites, and the like. The shear knives are
preferably hardened or otherwise treated to reduce wear.
[0262] Those skilled in the art will appreciate that the amount of
shear force applied by one or more shear knives 101 or 102
transversely against a web 74 is a function of many variables with
probably the most important or principal variables being the
polymer viscosity, the longitudinal web tension, and the
positioning of the shear knives 101 and 102 relative to the web 74
during operation.
[0263] When a suitable and preferred level of applied shear force
and web tensioning have been achieved to produce a product having
encapsulated or enveloped fibers and/or an internal coating, or
both, one can usually hear a distinctive sound in the region of a
shear blade 101 and 102. This sound can also be heard in the
vicinity of shear blades being used in the operation of other
processes described herein. This sound can in fact be used by an
operator as a rough guide as to whether or not the operator is
succeeding in producing a product with controlled polymer placement
containing enveloped fibers and/or an internal coating, or
both.
[0264] Blade roll 105 also functions as a compensator roll for
mechanically adjusting and controlling web tension before shear
thinning begins. Also, conveniently and preferably the web tension
is sensed electronically, and then roll 105 is automatically raised
or lowered to achieve web tensioning adjustments so as to maintain
a preset predetermined tension in web 74.
[0265] After passing over roll 107, the web 74 is passed over the
circumferential surface of a conventional padder roll 111. Between
the blade roll 107 and the padder roll 111, a flexible so-called
"flex-knife" or "Spanish knife" 100 is positioned. Preferably, the
blade of this flexible knife 100 is inclined at an angle with
respect to the web 74 passing thereagainst so that the knife 100
exerts a compressive force against the face 79 of web 74 with
opposed face 103 being entirely unsupported. The angle with respect
to a (hypothetical) perpendicular line extending into a
(hypothetical) straight line extending from the circumferential
edge of roll 107 to the circumferential edge of roll 111 can range
from about 30.degree. to about 140.degree. for the adjustment of
the inclination angle of the flex knife. To provide adjustability
for flexible knife 100, knife 100 is functionally associated with a
mounting bracket or back support 113 which in turn is adjustable
relative to an methods and apparatus frame (not shown).
[0266] In the embodiment shown in FIG. 12a, the padder roll 111 is
not employed as a web 74 treating means. It is not necessary to use
the padder roll 111 in all applications. It is typically only used
when tension is needed through the nip of the padder roll.
[0267] After leaving the mechanical tension compensator rolls 94,
95 and 96, web 74 is under reduced or preferably minimal tension
and is led along a pathway which extends over spacer rolls 113 and
114. Alternatively, the web 74 may pass directly from the tension
rolls 94, 95 and 96 into the curing oven 119. In the region over
spacer rolls 113 and 114, and generally between tension roll 96 and
idler roll 117, a platform 116 is conveniently positioned which can
incorporate suitable instrumentation panels, operating controls and
the like so that an operator can observe the operation of the
apparatus in accordance with this invention and then control and
regulate the same. A position which is suitable for operator
observation of a web in progress that is located in the vicinity of
a tenter frame 118 is desirable because it has been observed that a
web being processed can experience some distortion owing to the
forces exerted thereon. These distortions can be metered and
observed and then the tenter frame 118 adjusted by the operator so
that, as the web passes therethrough, the web can be straightened
or shaped either longitudinally or laterally, as desirable or
considered necessary for an individual web. If desired, the tenter
frame 118 can be automatically operated to apply tensioning forces
to a web in accordance with a predetermined program, or the like.
It is to be understood, however, that a tenter frame may not always
be necessary or desirable. Many webs may be processed in accordance
with the principles of this invention without use of a tenter frame
or other transverse tensioning device. In such cases, the web will
pass directly into the curing ovens from the tension rolls 94, 95
and 96 or from the spacer rolls 113 and 114.
[0268] The tenter frame 118 also provides the start of a new zone
of limited longitudinal and transverse tensioning which extends
forwardly along the web pathway from tenter frame 118 through oven
119 to a tension compensator, here shown as utilizing three tension
rolls 121, 122 and 123 which are part of a conventional mechanical
tension compensator subassembly which is similar in structure and
function to the compensator subassembly incorporating the
previously described tension rolls 94, 95 and 96. The tensioning
longitudinally of web 74 as it passes through oven 119 is employed
to control the web 74 as it passes through oven 119 as regards web
dimensional limits. This tensioning is chosen to be at a level
which does not introduce significant distortion into the web, yet
web sagging is avoided, as from thermal expansion and elongation.
Rollers (not shown) can be used in the oven 119 to avoid sagging
and to maintain uniform heat exposure. It has been found for many
applications that it is desirable to cure the treated web under
substantially no tension. It is preferable that the web be cured in
a relaxed state so that its original construction or the physics of
its construction can be retained. This is instrumental for
maintaining the correct hand and minimizing shrinkage.
[0269] In addition to serving as tension regulating means, the
rolls 121, 122 and 123 also serve to provide a cooling pathway for
the web 74 as it emerges from the oven 119 before it passes over
guide roller 124 and onto take-up roll 77.
[0270] The oven 119 functions to cure the polymer composition
selectively placed within the web 74. Oven 119 can be operated with
gas or other energy source. Furthermore, the oven could utilize
radiant heat, induction heat, convection, microwave energy or other
suitable means for effecting a cure which are known in the art.
Oven 119 can extend for from about 12 to about 20 yards.
[0271] Curing temperatures of from about 320.degree. to about
500.degree. F., applied for times of from about 2 minutes to about
30 seconds (depending upon the temperature and the polymer
composition) are desirable. If a curing accelerator is present in
the polymer, curing temperatures can be dropped down to
temperatures of about 265.degree. F. or even lower (with times
remaining in the range indicated).
[0272] In place of an oven, or in combination with an oven, a
source of radiation can be employed (electron beams, ultraviolet
light, or the like) to accomplish curing, if desired.
[0273] Less than the full heating capacity of the oven 119 can be
used, if desired. For example, only top heating or only bottom
heating with respect to the web can sometimes be used as compared
to a combination of both top and bottom heating.
[0274] The take-up roll 77 is operating at approximately the same
speed as the supply roll 76. When the rotational speeds of take-up
roll 77 are not synchronized with rotational speeds of the supply
roll 76, the tension roll combination of rolls 121, 122 and 123 can
be used to take up or reduce web slack, as the case may be.
[0275] Web transport speeds can vary widely; for example, from
about 2 yards per minute to about 90 yards per minute. Present
speeds are from about 35 yards per minute to about 50 yards per
minute.
[0276] The apparatus and processes described above can be used in
various forms or embodiments. Referring to FIGS. 12b and 12c, two
alternate variations or modes are seen. In such views, similar
components are similarly numbered but with the addition of single
prime marks thereto in the case of FIG. 12b and double prime marks
thereto in the case of FIG. 12c.
[0277] In FIG. 12b, a further stage of web pressurization is
introduced after the flex knife 112' and before the tenter frame
118'. Here, the web 74 after passage through the flex knife 112' is
passed through the nip region 126 existing between padder roll 111'
and associated transfer roll 127 where the web 74' is subjected to
compression between such rolls 127 and 111' for the purpose of
achieving a better distribution of polymer composition on web
74.
[0278] After leaving nip region 126, the web 74 is retained under
some compression against roll 127 by means of retaining bar or roll
128 for similar purposes. As discussed with reference to FIG. 12a,
the web 74 may pass directly into the oven 119' without utilizing
the tenter frame 118'. It is desirable that the web curing start
promptly after tension is released in the nip region 126, thus it
is preferred that the nip region 126 be located in close proximity
to the entrance to oven 119'.
[0279] If desired, the roll 128 can be replaced by a flex knife
(not shown) over whose edge the web 74' passes after departure from
roll 127. The flex knife can accomplish substantial further polymer
distribution in web 74.
[0280] Referring to FIG. 12c, there is seen an embodiment where the
web 74 is passed through the nip region of rolls 111" and 127".
Here not only is use of the mechanical tension roll combination
having rolls 94, 95 and 96 (as in FIG. 12a) eliminated, but also
the rolls 111" and 127" serve to end the region of high
longitudinal tension in the stages of blade or knife application to
web 74 and to provide the desired reduced tension for web passage
through a curing station, here illustrated by oven 119" which may
or may not use the intervening tenter 118".
[0281] FIG. 14 depicts a schematic, side elevational view of a
preferred embodiment or methods and apparatus for practicing the
present invention. In this embodiment a continuous web 302 is moved
under tension along a web pathway from a supply roll 301 to a
take-up roll 327.
[0282] The primary tension is a result of the differential rate
between the driven entrance pull stand designated as 306 and the
driven exit pull stand designated as 322, whereby the exit pull
stand 322 is driven at a rate faster than the entrance pull stand
306. Other controllable factors which effect tension are the
diameters of blade rolls 309, 314, 316, 318; the vertical depth of
blades 311, 315, 317; the durometer of the entrance pull stand
rolls 304, 305 and rubber roll 321 of the exit pull stand, and the
friction as the web passes under the blades.
[0283] Web 302 passes between the nip of the two rolls 304 and 305
of the entry pull stand 306. The entry nip is adjustable to produce
a force of from about 100 lbs. to about 5 tons on the web, passing
between the two rolls. The weight of top roll 305 provides an even
distribution of force throughout the web width. Web 302 is
flattened at this point and the interstitial spaces are reduced
laterally and longitudinally. Bottom roll 304 has micro-positioning
capability to provide for gap adjustment and alignment. The top
roll 305 composition is chosen based on the durometer of a urethane
or rubber roll.
[0284] Web 302 continues to move along past idler roll 308 and
blade roll 309 and forms an entry angle a and an exit angle .beta.
with blade 311. Blade 311 is illustratively shown in FIG. 4b. For
purposes of the apparatus of FIG. 14, the blade in FIG. 4b has a
leading edge 250 and a trailing edge 260. Entry angle .alpha. can
be varied by adjusting: (a) the height and diameter of blade rolls
309 and 314, (b) the horizontal position of blade rolls 309 and
314, (c) the angle of blade 311, and (d) the height of blade 311.
Similarly, the entry and exit angles of blades 315 and 317, can be
varied by adjusting the same devices surrounding each blade.
[0285] For illustrative purposes, increasing the height and
diameter of blade roll 309 decreases entry angle .alpha.. Rotating
blade 311 clockwise, with web 302 running left to right, increases
entry angle .alpha.. Likewise, rotating blade 311
counter-clockwise, with web 302 running left to right, decreases
entry angle .alpha.. Decreasing the distance between blade roll 309
and blade 311 decreases entry angle .alpha.. Increasing the
downward depth of blade 311 into web 302 decreases entry angle
.alpha..
[0286] The angle of blades 311, 315, and 317 are completely
changeable and fully rotational to 360.degree.. The fully
rotational axis provides an opportunity for more than one blade per
rotational axis. Therefore, a second blade having a different
thickness, bevel, shape, resonance, texture, or material can be
mounted. Ideally the apparatus contains two or three blades per
blade mount. The blade mounts are not shown. The force or pressure
of blade 311 applied against web 302 is determined by the vertical
positioning of blade 311 in the blade mount. The greater the
downward depth of blade 311, the greater the force or pressure.
Blade pressure against the web is also accomplished through the
tension of the web as described above.
[0287] The same line components that affect entry angle .beta.,
also affect exit angle .beta.. Any changes in the height, diameter,
or horizontal positioning of blade rolls 309 and 314, affects exit
angle .beta.. If the angle of blade 311 is rotated clockwise as
described above, entry angle .alpha. increases, thus decreasing
exit angle .beta..
[0288] As web 302 moves from left to right in FIG. 14, polymer is
deposited on web 302 with polymer applicator or dispersion means
310. Polymer applicator 310 can be a pump, a hose, or any available
application device for applying polymer onto the surface of the
web. Polymer applicator 310 is located directly in front of blade
311. The polymer is immediately shear thinned, placed into, and
extracted from web 302 by the leading edge of blade 311, thus
controlling the amount of polymer remaining in web 302. The bevel
of blade 311 can effect entry angle .alpha. and the sharpness of
the leading edge of blade 311. A sharper leading edge has a greater
ability to push the weave or structural elements of web 302
longitudinally and traversely, increasing the size of the
interstitial spaces. As the web passes the leading edge of blade
311, the interstitial spaces snap back or contract to their
original size.
[0289] As web 302 moves from left to right in FIG. 14, the process
of shear thinning and placing polymer into and extracting it out of
web 302 is repeated at subsequent blades 315 and 317, thus
controllably placing the polymer throughout web 302. Web 302 then
passes over idler roll 319 and between driven exit pull stand 322
which consists of rolls 320 and 321. Pull roll 320 is a driven roll
proportionally driven at a predetermined rate slower than entry
roll 304. Pull roll 321 does not apply pressure so much as it
achieves a high degree of surface area in which web 302 must come
into contact with. The larger the surface area, the higher the
degree of contact friction. Pull roll 321 can be adjusted to have
sufficient downward force to eliminate any slippage between web 302
and pull roll 320.
[0290] After web 302 passes from exit stand 322, it then moves into
an oven 323 for curing. Rolls 324, 325, and 326 provide a tension
regulating means and also serve to provide a cooling pathway for
web 302 as it emerges from oven 323 before passing onto take-up
roll 327.
[0291] The cure temperature of oven 323 is thermostatically
controlled to a predetermined temperature for web 302 and the
polymers used. Machine runs of new webs are first tested with hand
pulls to determine adhesion, cure temperature, potentials of
performance values, drapability, aesthetics, etc. The effect on web
302 depends on the temperature of oven 323, dwell time and curing
rate of the polymer. Web 302 may expand slightly from the heat.
[0292] Oven 323 functions to cure the polymer composition that is
controllably placed into web 302. Oven 323 can be operated with gas
or other energy sources. Furthermore, oven 323 could utilize
radiant heat, induction heat, convection, microwave energy or other
suitable means for effecting a cure. Oven 323 can extend from about
12 to 20 yards, with 15 yards long being convenient.
[0293] Curing temperatures from about 320.degree. F. to about
500.degree. F., applied for times of from about two minutes to
about thirty seconds (depending on the temperature and the polymer
composition) are desirable. If a curing accelerator is present in
the polymer, curing temperatures can be dropped down to
temperatures of about 265.degree. F. or even lower (with times
remaining in the range indicated).
[0294] The cure temperature of oven 323 and the source and type of
cure energy, are controlled for a number of reasons. The cure
temperature of oven 323 is controlled to achieve the desired
crosslinked state; either partial or full. The source and type of
energy can also affect the placement of the polymer and additives.
In place of an oven, or in combination with an oven, a source of
radiation can be employed (electron beams, ultraviolet light, or
the like) to accomplish curing, if desired. For example, by using a
high degree of specific infrared and some convection heat energy
for cure, some additives can be staged to migrate and/or bloom to
the polymer surfaces.
[0295] Oven cure dwell time is the duration of time the web is in
oven 323. Oven cure dwell time is determined by the speed of the
oven's conveyor and physical length of the oven. If the dwell time
and temperature for a particular web is at maximum, then the oven
conveyor speed would dictate the speed of the entire process line
or the length of the oven would have to be extended in order to
increase the dwell time to assure proper final curing of the
web.
[0296] Take-up roll 327 is operated at approximately the same speed
as supply roll 301. When the rotational speeds of take-up roll 327
are not synchronized with rotational speeds of supply roll 301, the
tension roll combination of rolls 324, 325, and 326 can be used to
reduce web slack.
[0297] Web speed is proportional to the variable speed of the motor
which drives entrance pull stand 306 and exit pull stand 322. Web
speed can effect the physics of the polymers as web 302 passes
under blades 311, 315, and 317. Web transport speeds can vary
widely; for example, from about two yards per minute to about
ninety yards per minute.
[0298] Typically, and preferably, webs of this invention are
characterized by having fiber envelopment layers which range from
about 0.1 to about 50 microns.
[0299] A presently preferred web which is both fluorochemical and
silicone polymer treated and which is breathable, water resistant
and rewashable is characterized as being a longitudinally
tensionable porous flexible fibrous web having opposed
substantially parallel surfaces that are comprised of associated
fibers with interstices between the fibers, or is a matrix having
cells or pores therein. The web is substantially uniformly
impregnated with a fluorochemical and thereafter treated with a
silicone polymer composition, to form a web having an internal
layer within the web wherein the outer surfaces of the web are
substantially free of silicone polymer and the web is breathable
and water resistant or waterproof. At least a portion of the fibers
or cell walls are encapsulated or enveloped. At least one surface
of the web is characterized by having a visual appearance which is
substantially the same as the visual appearance of one surface of
the starting porous web.
[0300] When the web has fibers comprised of a synthetic polymer,
the polymer is preferably selected from the group consisting of
polyamides, polyesters, polyolefins, regenerated cellulose,
cellulose acetate, and mixtures thereof.
[0301] Preferred webs of this invention are more specifically
characterized by having a water drop contact angle in the range of
about 90.degree. to about 160.degree.; a rewash capability of at
least about 3; a breathability of at least about 35% of untreated
substrate web; and a water repellency rating of at least about 80
prior to washing.
[0302] A general process for making a porous web of this invention
comprises the steps of: tensioning a flexible, porous web as above
characterized, applying a curable shear thinnable polymer
composition to at least one web surface and then moving over and
against one surface of the tensioned web a uniformly applied
localized shear force to: shear thin the polymer composition,
uniformly place the composition within the web, at least partially
individually encapsulate or envelop surface portions of at least
some of said fibers through the web matrix or position said
composition in a desired web internal region or some combination of
both. Thereafter, the web is subjected to conditions sufficient to
cure the composition in said web. Curing is accomplished by heat,
by radiation, or both.
[0303] A presently preferred process for making a fluorochemical
and silicone resin treated web having breathability, water
resistance and rewashability which is adapted for continuous
operation comprises the successive steps of: impregnating the web
with a fluorochemical, longitudinally tensioning the fluorochemical
impregnated web while sequentially first applying to one surface
thereof a curable silicone polymer composition and concurrently
applying a transversely exerted localized compressive force against
said surface, and moving over said surface of the web substantially
rigid shearing means which exerts transversely an applied,
localized shear force against said surface to shear thin the
polymer and wipe away exposed portions of silicone polymer
composition on said surface, thereby forming an internal layer of
silicone polymer and/or enveloping at least some of the fibers or
passageways through the matrix, or both; and curing the silicone
polymer composition in the web.
[0304] The fluorochemical controlled placement operation is
conveniently and preferably carried out by the steps of:
substantially completely saturating the web with a solution or
dispersion of a fluorochemical composition in a carrier liquid;
compressing the saturated web to remove therefrom excess portions
of said dispersion; and heating said web to evaporate the carrier
liquid therefrom. However, any convenient process can be used for
accomplishing fluorochemical pretreatment of a web to be used in
this invention.
[0305] The following text concerns the theory of the invention as
it is now understood; however, there is no intent herein to be
bound by such theory.
[0306] The presently preferred polymer composition used in the
treatment of webs by this invention is a non-Newtonian liquid
exhibiting thixotropic, pseudoplastic behavior. Such a liquid is
temporarily lowered in viscosity by high pressure shear forces.
[0307] One aspect of the invention is a recognition that when high
forces or sufficient energy are applied to curable polymer
compositions, the viscosities of these materials can be greatly
reduced. Conversely, when subjected to curing, the same liquid
composition sets to a solid form which can have a consistency
comparable to that of a hard elastomeric rubber. The internal and
external Theological control of polymer materials achieved by the
present invention is believed to be of an extreme level, even for
thixotropes. When subjected to shear force, the polymer composition
is shear thinned and can flow more readily, perhaps comparably, to
water.
[0308] The invention preferably employs a combination of: (i)
mechanical pressure to shear thin and place a polymer composition
into a porous web; (ii) an optional porous web pretreatment with a
water repellent chemical, such as a fluorochemical, which is
theorized to reduce the surface tension characteristics of the web
and create a favorable surface contact angle between the polymer
composition and the treated web which subsequently allows, under
pressure and shear force exerted upon an applied polymer
composition, the production and creation of an internal coating or
layer which envelopes fibers or lines cell walls in a localized
region within the web as a result of polymer flow in the web or
which encapsulates the fibers within the web; and (iii) a polymer
composition impregnant preferably having favorable rheological and
viscosity properties which responds to such working pressures and
forces, and is controllably placed into, and distributed in a web.
This combination produces a web having the capability for a high
degree of performance. This product is achieved through pressure
controlled placement and applied shear forces brought to bear upon
a web so as to cause controlled movement and flow of a polymer
composition into and through a web. Preferably, repeated
compressive applications of pressure or successive applications of
localized shear forces upon the polymer in the web are
employed.
[0309] By the preferred use of such combination, a relationship is
established between the respective surface tensions of the polymer
and the web, creating a specific contact angle. The polymer
responds to a water repellent fluorochemical pretreatment of the
substrate so as to permit enhanced flow characteristics of the
polymer into the web. However, the boundary or edge of the polymer
is moved, preferably repeatedly, in response to applied suitable
forces into the interior region of a porous web so as to cause thin
films of the polymer to develop on the fiber surfaces and to be
placed where desired in the web.
[0310] Thixotropic behavior is preferably built into a polymer used
in the invention by either polymer selection or design or
additive/filler design. For example, it now appears that
thixotropic behavior can be accentuated by introducing into a
polymer composition certain additives that are believed to impart
enhanced thixotropy to the resulting composition. A lower viscosity
at high shear rates (during application to a web) is believed to
facilitate polymer flow and application to a web, whereas a polymer
with high viscosity, or applied at a low shear rate (before and/or
after application) actually may retard or prevent structural
element (including fiber) envelopment or encapsulation.
[0311] Illustratively, the practice of this invention can be
considered to occur in stages:
[0312] In stage 1, a silicone polymer composition impregnant is
prepared. It can be purchased commercially and comes in typically
two parts designated as A and B. For example, in a silicone polymer
composition, as taught in U.S. Pat. No. 4,472,470, a base vinyl
terminated polysiloxane is the A part, while a liquid
organohydrogensiloxane controlled crosslinking agent is the B part.
Certain remaining components, such as a resinous organopolysiloxane
copolymer and a platinum catalyst may (or can) apparently initially
be in either part A or part B.
[0313] Stage 2 can be considered to involve the mixing of such a
product's parts with or without additives. Changes in viscosity can
be obtained and measured based on applied shear rates and shear
stresses. Such changes can be experienced by a polymer with or
without additives. Up to a 99% reduction in viscosity of a liquid
silicone polymer composition is believed to be obtainable by the
shear forces involved in the shear thinning and forcing of a
silicone polymer composition impregnant into a web. Thereafter, a
very substantial increase in polymer viscosity is believed to be
obtainable taking into account these same factors. Normally, the
most significant factor is now believed to be the shear gradient
that typically reduces the viscosity of the polymer below the
starting or rest viscosity.
[0314] Stage 3 can be considered to be the pressure introduction
stage. Up to a 99% reduction of the polymer viscosity is believed
to be obtainable due to the applied shear forces, elapsed time,
temperature, radiation and/or chemical changes. Thereafter, a
significant increase or even more in the resulting polymer
viscosity is believed to be obtainable. In this stage, partial
curing of the polymer may take place. Most commonly, polymer
viscosity is substantially decreased during the pressure controlled
placement Stage 3 by the application of shear forces.
[0315] Stage 4 can be considered to be the first stage internal
matrix dispersing and reintroduction with metering, and also
recovery and recycle of excess polymer. Typically, within this
Stage 4, the shear forces cause a substantial but temporary
lowering of polymer viscosity, causing it to flow upon and into the
three-dimensional structure of the web. The initial viscoelastic
character of the polymer is typically theorized to be recovered
almost immediately after shear forces are removed.
[0316] Stage 5 can be considered to be a second stage internal
matrix dispersing and reintroduction with metering and also
recovery and recycling of excess polymer. The variations in the
viscosity of the polymer are equivalent to Stage 4. The viscosity
of the polymer is again lowered causing it to flow within the web.
Because of the application of repeated shear force induced
reductions in viscosity, the thixotropic behavior of a polymer may
not undergo complete recovery, following each application of shear
force and the viscosity of the polymer may not revert to its
original placement values. The polymer composition is believed to
have the capacity to form enveloping internal coating in a
predetermined region wherein the interstices or open cells are
substantially completely filled within the three-dimensional matrix
constituting a web during the time intervals that the is caused to
flow under pressure in and about matrix components. In between
these times, the polymer may recover substantially all of its
initial high viscosity, although perhaps slightly less so with each
repeated application of shearing pressure or force.
[0317] Stage 6 can be considered to be occurring just as curing is
begun, and just as heat is introduced.
[0318] Stage 7 can be considered to be occurring with regard to the
exertion of control of curing. Typically, at least a partial curing
(including controlled cross-linking and/or polymerizing) is
obtained by relatively low temperatures applied for relatively
short times. For example, when light cotton, nylon, or similar
fabrics are being treated, temperatures under about 350.degree.,
applied for under about 10 seconds, result in partial curing.
[0319] FIG. 8, consisting of FIGS. 8a through 8d, shows four graphs
illustrating four ways that could be used for plotting polymer
rheological behavior: (a) shear rate versus shear stress (uniform
scales), (b) shear rate versus shear stress (log scales), (c)
viscosity versus shear rate (uniform scales), and (d) viscosity
versus shear rate (log scales), if desired, in the practice of this
invention. Only the log versus log scales are believed to be
capable of encompassing a full range of values for the three
indicated variables. The graphs represent some broad ranges of
viscosity changes relative to shear stress that could be under-one
by a given silicone polymer composition during execution of a given
pressured controlled placement procedure as taught herein.
[0320] For the purposes of the present invention, the term "surface
tension" can be considered to have reference to a single factor
consisting of such variables as intermolecular, or secondary,
bonding forces, such as permanent dipole forces, induced forces,
dispersion or nonpolar van der Waals forces, and hydrogen bonding
forces. The strong primary bonding forces at an interface due to a
chemical reaction are theorized to be excluded from surface tension
effects; however, it is noted that even a small degree of chemical
reactivity can have a tremendous influence on wetting effects and
behavior affected by surface tension.
[0321] Surface tension is believed to induce wetting effects which
can influence the behavior of a polymer composition impregnant
relative to the formation of either a fiber enveloped layer
therewith in a fibrous porous web, fiber encapsulation or both. For
example, adhesion is theorized to be a wetting effect. Spontaneous
adhesion always occurs for contact angles less than about
90.degree.. However, for a combination of a rough surface and a
contact angle over 90.degree., adhesion may or may not occur. In
fact, roughness becomes antagonistic to adhesion, and adhesion
becomes less probable as roughness increases.
[0322] Also, penetration is theorized to be a wetting effect.
Spontaneous penetration occurs for contact angles less than about
90.degree., and does not occur for contact angles over about
90.degree.. The roughness of a solid surface accentuates either the
penetration or the repellency action, but has no influence on which
type of wetting takes place.
[0323] In addition, spreading is theorized to be a wetting effect.
Retraction occurs for contact angles over 90.degree. or over planar
surfaces for any contact angle. However, spontaneous spreading for
contact angles less than 90.degree., especially for small contact
angles, may be induced by surface roughness.
[0324] FIG. 9 is a schematic vector diagram illustrating the
surface tension forces acting at the vertex boundary line of a
liquid contact angle on a planar solid surface. It illustrates how
surface tension forces might be measured between a silicone polymer
composition and a fiber of a web (or a fabric) as treated by the
invention.
[0325] FIG. 10 is a graph relating the contact angle over a smooth
solid surface as a function of .theta. and i that apply
respectively, to adhesion (I cos .theta.+1), penetration (i cos
.theta.), and spreading (i cos .theta.-1).
[0326] Regions of adhesion versus abhesion, penetration versus
repellency, and spreading versus retraction are shown by shaded
areas. FIG. 10 illustrates what is theorized to be the relationship
of a silicone polymer composition to silicone polymer composition
solids in a treated web as regards such factors as adhesion,
penetration, spreading, and retraction.
[0327] FIG. 11, consisting of FIGS. 11a through 11d, shows
representative viscosity profiles plotted on log viscosity versus
log shear rate graphs for (a) pseudoplastic flow, (b) dilatant
flow, (c) pseudoplastic flow with superimposed thixotropic
behavior, and (d) laminar Newtonian flow that erupts into turbulent
flow at a critical transition point.
[0328] FIGS. 11a through 11d show a broad range of illustrative
flow characteristics that could be demonstrated by silicone polymer
composition impregnants suitable for use in this invention using
pressured controlled placement of a web as taught herein.
[0329] For purposes of this invention, the term "wetting" is used
to designate such processes as adhesion, penetration, spreading,
and cohesion. If wetting transpires as a spontaneous process, then
adhesion and penetration are assured when the solid surface tension
exceeds the liquid surface tension. Surface roughness promotes
these spontaneous wetting actions. On the other hand, no such
generalizations can be made when the solid surface tension is less
than the liquid surface tension.
[0330] Surface tension is measured as by S.T.L. units for liquid
and by S.T.S. units for solids; both units are dyns/centimeter.
When S.T.S. is less than S.T.L., then wetting is less ubiquitous
and prediction of wetting behavior is more difficult. However, by
taking advantage of the liquid/solid contact angle that forms when
a liquid retracts over a solid, it is possible to calculate with
reasonable accuracy the wetting behavior that can be expected. The
reduction in liquid surface area can be computed in terms of the
contact angle that the liquid makes with the solid surface. Contact
angles are always measured in the liquid phase There is a point of
equilibrium where the surface tension forces become balanced.
[0331] By measuring the contact angle of a liquid on a solid, the
wetting behavior of the liquid impregnant can be measured.
[0332] This invention is further illustrated by the following
examples, which are not to be construed in any way as imposing
limitations upon the scope thereof. On the contrary, it is to be
clearly understood that resort may be had to various other
embodiments, modifications, and equivalents thereof, which, after
reading the description herein, may suggest themselves to those
skilled in the art without departing from the spirit of the present
invention and/or the scope of the appended claims.
EXAMPLES:
EXAMPLE 1: Liquid Silicone Polymer Preparation
[0333] 100 parts by weight of the curable liquid silicone polymer
available commercially from Mobay as "Silopren.RTM. LSR 2530" was
mixed in a 1:1 ratio, as recommended by the manufacturer. A
Hockmayer F dispersion blade at low torque and high shear was used
to do the mixing. To this mixture were added 5 parts by weight of
BSF "Uvinul 400" and {fraction (5/10)} parts by weight Dow Coming
7127 accelerator, believed to be a polysiloxane but containing an
undisclosed active accelerated ingredient.
EXAMPLES 2-19: Liquid Silicone Polymer Preparation
[0334] The procedure of Example 1 was repeated with various other
curable viscous liquid silicone polymer compositions commercially
available. To this product system is added a substituted
benzophenone and other additives, the result of which are shown in
Table II. All parts are by weight.
2TABLE II Illustrative Silicone Resin Compositions MIXTURE STARTING
RATIO OF SUBSTITUTED EX. SILICONE PACKAGED BENZOPHENONE OTHER
ADDITIVES NO. RESIN COMPONENTS.sup.1 NAME PARTS NAME PARTS 1
Silopren .RTM. 1:1 Uvinul 400 5 7127 5/10 LSR 2530 Accelerator 2
Silastic .RTM. 1:1 Uvinul 400 5 Syl-Off .RTM. 50 595 LSR
7611.sup.(2) 3 SLE 5100 10:1 Uvinul 400 5 Sylox .RTM. 2.sup.(3) 8
Liquid BC- 1:1 10 4 Silopren .RTM. 1:1 Uvinul 400 5 Hydral .RTM.
710.sup.(4) 10 LSR 2530 5 Silopren .RTM. 1:1 Uvinul 400 5 Silopren
.RTM. LSR 1 LSR 2530 Z3042.sup.(5) 6 SLE 5500 10:1 Uvinul 400 5 7
Silopren .RTM. 1:1 Uvinul 400 5 LSR 2540 8 SLE 5300 10:1 Uvinul 400
5 9 SLE 5106 10:1 Uvinul 400 5 10 Silopren .RTM. 1:1 Uvinul 400 5
Slattening 4 LSR 2530 Agent OK412 .RTM..sup.(6) 11 Silopren .RTM.
1:1 Uvinul 400 5 Nalco.sup.(5) 1SJ- 50 LST 2530 612 Colloidal
Silica.sup.(7) 12 Silopren .RTM. 1:1 Uvinul 400 5 Nalco .RTM. 1SJ-
LSR 2530 614 Colloidal Alumina.sup.(8) 13 Silastic .RTM. 1:1 Uvinul
400 5 200 Fluid.sup.(7) 7 595 LSR 14 Silopren .RTM. 1:1 Uvinul 400
5 LSR 2530 15 Silastic .RTM. 1:1 Uvinul 400 5 Zepel .RTM.
7040.sup.(10) 3 595 LSR 16 Silastic .RTM. 1:1 Uvinul 400 5 Zonyl
.RTM. UR.sup.(11) 1/10 595 LSR 17 Silastic .RTM. 1:1 Uvinul 400 5
Zinyl .RTM. FSN- 1/10 595 LSR 100.sup.(12) 18 Silopren .RTM. 1:1
Uvinul 400 5 DLX-600 .RTM..sup.(13) 5 LST 2530 19 Silopren .RTM.
1:1 Uvinul 400 5 TE-3608 .RTM..sup.(14) 5 LSR 2530 Table II
Footnotes: .sup.(1)Ratio listed is that recommended by the
manufacturer. .sup.(2)Syl-off .RTM. (registered trademark of Dow
Corning) is a crosslinker. .sup.(3)Sylox .RTM. 2 (registered
trademark of W.R. Grace Co.) is a synthetic amorphous silica.
.sup.(4)Hydral .RTM. 710 (registered trademark of Alcoa) is
hydrated aluminum oxide. .sup.(5)Silopren .RTM. LSR Z/3042
(registered trademark of Mobay) is a silicone primer (bonding
agent) mixture. .sup.(6)Flattening Agent OK412 .RTM. (registered
Trademark of Degussa Corp.) is a wax coated silicon. dioxide.
.sup.(7)Nalco .RTM. 1SJ-612 Colloidal Silica (registered trademark
of Nalco Chemical Company) is an aqueous solution of silica and
alumina. .sup.(8)Nalco .RTM. 1SJ-614 Colloidal Alumina (registered
trademark of Nalco Chemical Company) is an aqueous colloidal
alumina dispersion. .sup.(9)200 Fluid (registered trademark of Dow
Corning) is a 100 centistoke viscosity dimethylpolysiloxane.
.sup.(10)Zepel .RTM. 7040 (registered trademark of duPont) is a
nonionic fluoropolymer. .sup.(11)Zonyl .RTM. UR (registered
trademark of duPont) is an anionic fluorosurfactant. .sup.(12)Zonyl
.RTM. FSN-100 (registered trademark of duPont) is a nonionic
fluorosurfactant. .sup.(13)DLX-6000 .RTM. (registered trademark of
duPont) is polytetrafluoroethylene micropowder. .sup.(14)TE-3608
.RTM. (registered trademark of duPont) is a polytetrafluoroethylene
micropowder.
EXAMPLE 20: Internally Coated Fiber Encapsulated, Interstice Filled
Fabric Preparation
[0335] A complete, stepwise, application of the inventive method in
the production of an encapsulated fiber fabric was as follows.
[0336] The selected base fabric was TACTEL.RTM. (gold color)
#612071 available from ICI Americas, Inc. through their agent,
Arthur Kahn, Inc. This fabric was 100% woven nylon. If desired,
this and other fabrics may be calendered to modify surface texture.
The fabric was weighed and measured. Its initial weight is 3.1
ounces per square yard. Its thickness equals 9 mils. The fabric was
next washed with detergent, rinsed thoroughly, and hung to air dry.
The fabric was soaked in water, wrung dry, and weighed. The water
retained was equal to 0.8 g water/g fabric. The fabric was then
treated with a water repellent fluorochemical, a 2% solution by
weight of Zepel.RTM. 7040. In order to do so the fabric must be
soaked in a 2.5% solution of Zepel.RTM. water-repellent chemical in
distilled water. This was because: 2 1 g fabric * ( 0.02 ) 0.8 g
water = 0.025
[0337] The treated fabric was then run through a wringer and air
dried. Next, the fabric was heated in an oven for 1 minute at
350.degree.. This heating sinters the water repellent
fluorochemical. The fabric with its fluorochemical residue is then
run as in the FIG. 7 embodiment, in a vertical configuration and is
described below. The fabric is run from a roll that incorporates
significant braking or clutching to initiate the tension required
for controlled material alignment and coating during application.
The fabric web travels through a series of idler rolls ending at
the application trough. As it passes the application trough, it
picks up a thin coating of silicone impregnant and then moves under
a shear blade that is parallel to the floor. The silicone
impregnant is applied at 1.0 oz./sq. yd. and continues under a flex
blade that is also parallel to the floor.
[0338] Multiple process stages of running the fabric with applied
impregnant under the blades are preferably made. The multiple
process stages are important, and are normally necessary. The
impregnant is Mobay 2530 A/B in a 1:1 ratio and can be considered
to be a viscoelastic liquid that flows only under the shear forces
resulting from the pressured controlled placement. The impregnant
is believed to return very substantially to its original viscous
condition almost immediately upon release of the pressure. The
impregnant was believed to flow a short distance within the matrix
of the fabric during the short time that it was, because of
pressure shearing forces, of lowered viscosity. Therefore, a number
of "flows" may be usefully generated in a number of passes in order
to properly distribute the impregnant in its preferred position
substantially encapsulating the surfaces of the fabric's
fibers.
[0339] Finally, the impregnated fabric was run through a line oven,
of approximately 10 yards in length, at 4-6 yards per minute, and
was cured at 325-350.degree. F. It then passes through a series of
idler rollers and is rolled up on a take-up roll, completing the
tension zone. The resultant fabric has a non-tacky thin film of
silicone that was internally coated to form a fiber encapsulated,
interstice-filled layer in the fabric.
EXAMPLE 21: Evaluation of Fiber Encapsulated Fabric Properties
[0340] The test results of the original versus the produced fiber
encapsulated fabric of Example 20 were as follows:
3TABLE III ORIGINAL FABRIC FABRIC ENCAPSULATED Spray Rating (1) 20
100 (reverse = 100) Rain Test (2) Fail Pass Abrasion Test (cycles)
(3) 1,800 3,200 Moisture Penetration (4) Saturated 0.0 g
Hydrostatic Resistance (psi) (5) 1 2 MVTR (g/M.sup.2/day)* (6)
4,414 2,362 Weight (oz/yd.sup.2) 3.1 4.1 Amount Impregnated = 1.4
oz/yd.sup.2 *Environmental chamber at 104.degree. F. and 74%
humidity.
[0341]
4 TABLE IV LAUNDERING TEST TIMES WASHED (Spray Ratings) Initial 5X
10X 15X Impregnated Side 100 90 90 90 Reverse Side 100 90 90 90
Unimpregnated Treated Fabric 100 80 80 40 Accelerated Weathering
Test (8) Samples placed in QUV weatherometer for 72 hours. Original
= 7 Impregnated Side = 9 Reverse Side = 8
[0342] (1) The spray test was conducted in accordance with AATCC
22-1974. It measures water repellency of a fabric sample on a scale
of 0-100, with a reading of 100 designating a completely water
repellent fabric.
[0343] (2) The rain test was conducted in accordance with AATCC
35-1985. It measures resistance of a fabric sample to penetration
of water under static pressure from a shower head of 3 feet/5
minutes. A fabric is stormproof when less than 1.0 gram of water is
absorbed by a standardized blotter used in the test.
[0344] (3) The abrasion test was conducted in accordance with
Federal Test Method Standard 191 A, Method 5306. Abrasion
resistance is measured by mounting a fabric sample on a Taber
Abraser Model 174 and measuring the number of cycles before the
fabric begins tearing apart.
[0345] (4) The hydrostatic resistance test was conducted in accord
with Federal Test Method Standard 191A, Method 5512. The test
measures a fabric samples' resistance to water under pressure using
the Mullen's Burst Test methods and apparatus. Test results are
expressed in pounds per square inch at which water beads penetrate
the fabric.
[0346] (5) The moisture vapor transmission (MVTR) test was
conducted in accordance with ASTM E96-B. The test measures the
amount of moisture vapor passing through a fabric sample in a
controlled environment during a 24 hour period. The obtained MVTR
figure is expressed in grams of water/square meter of surface/24
hour day. The environmental chamber was held at 104.degree. F. and
47% humidity.
[0347] (6) The moisture vapor transmission (MVTR) test was
conducted in accordance with ASTM E96-B. The test measures the
amount of moisture vapor passing through a fabric sample in a
controlled environment during a 24 hour period. The obtained MVTR
figure is expressed in grams of water/square meter of surface/24
hour day. The environmental chamber was held at 104.degree. F. and
478 humidity.
[0348] (7) A laundering test of the conventional household type was
performed. Fabric samples were washed with Tide.RTM. detergent.
There was no drying. A spray test was subsequently carried out
after each wash to determine the effect of the washing.
[0349] (8) The accelerated weathering test was conducted in
accordance with ASTM G-53. Samples of original and impregnated
fabrics were placed in the weatherometer of QUV Company and results
were compared. (All readings were based on a graduated color scale
of 0-20; 10 designated the original color, while 0 designated a
white out.)
EXAMPLE 22: Description of Fabric Controlled Placement Through
Scanning Electron Microscope (SEM) Photomicrographs
[0350] FIGS. 3a, 3b and 3c were taken using a Cambridge 360
scanning electron microscope. The samples were cut using Teflon
coated razor blades, mounted on 1/2 inch diameter aluminum stubs
and coated with a gold/palladium alloy.
[0351] FIG. 3a is a photomicrograph of the gold color Tactel fabric
described in Example 20. The surface of the material has been
magnified 120 times and shows that the cured silicone polymer
impregnant is present as a thin film, or coating, or layer within
the material and envelopes at least a portion of the fibers. The
fiber bundles are somewhat distinguishable in the weave, but each
filament in the fiber bundles is not individually distinct.
[0352] The sample in FIG. 3b has been magnified 600 times and shows
the cross-section of a fiber bundle from the same Gold Tactel in
FIG. 3a. The cured silicone polymer impregnant envelopes at least a
portion of the fibers. The interstices or void areas between
filaments in the region of the internal coating are mostly filled
or plugged by such impregnant. However, the web remains breathable
and because of the impregnant barrier, is either water resistant or
waterproof.
[0353] FIG. 3c is the side of the fabric in FIG. 1 opposite from
which the silicone polymer impregnant was applied. The silicone
polymer impregnant is most readily apparent at the fiber bundle
interstices and not visible in the fiber bundles themselves.
EXAMPLE 23: Fiber Enveloped Fabric Preparation
[0354] The selected base fabric was Arthur Kahn TACTEL.RTM. (hot
coral) #70146. This fabric is 100% nylon. The fabric was pretreated
at Cal-Pacific (a commercial finisher of fabrics) with duPont
ZEPEL.RTM. 6700. The impregnant composition is Mobay LSR 2530 A/B
in a 1:1 ratio=5% W UVINUL.RTM. 400 (5% of total weight of Mobay
LSR). Controlled placement of this composition was performed in a
three stage continuous process using equipment as shown in FIG. 7
consisting of the following procedure:
[0355] The composition was applied to the fabric at (a) a pressure
of 3 lbs./linear inch, utilizing (b) a shear (bar) knife at a high
pressure, and at a 90.degree. angle to the fabric (the edge of the
knife is milled sharp). The rate of application is at approximately
1.0 oz./sq. yd. A flex knife was then applied at a 45.degree. angle
with the recovery system utilizing gravity. For both (a) and (b)
above, the microweb pressure was applied at a low web speed on a
roller system varied at from about 260-400 yards per hour. Next,
the fabric is cured using an upper oven (lower oven turned off) at
a temperature of about 320-330.degree. F. The fabric was in the
oven for approximately 3 to 4 minutes. The impregnant cures to a
non-tacky thin film, as in the previous example.
EXAMPLE 24: Prior Art Silicone Polymer Treated Fabric
[0356] The fabric resulting from a prior art application of a
viscous liquid curable silicone polymer composition is shown in
FIG. 2. The photographic view of FIG. 2 is at 150X magnification.
It shows a polyester and cotton cloth blend into which Dow Corning
590 LSR silicone polymer composition has been coated by a procedure
of the prior art. The fabric side shown in FIG. 2 is the top, or
treatment, side, which was the fabric side upon which coating was
accomplished.
[0357] As shown by the example of the treated fabric of FIG. 2, the
prior art impregnated fabric is characterized by a high degree of
disorder. A large number of particulates (typical) appear to litter
the surface of the fabric. A substantial portion of the area of the
surface, which appears to be a solid layer, is silicone polymer
composition. Certain yarn fragments can be observed to protrude
through the surface of this silicone polymer composition.
Additionally, the silicone polymer composition on either the
polyester or the cotton fibers, is not an encapsulation layer, but
rather a matrix with the coated fibers being in general disarray,
probably from forces occurring during the indicated prior art
silicone polymer composition application procedure. Although
silicone polymer composition is present upon the yarn or fiber
surfaces of the substrate, and certainly is present as a layer upon
the exterior surface of the three-dimensional fabric body, the
silicone polymer composition has not controllably and individually
encapsulated the fibers and left the interstices between fibers
largely devoid of such polymer. In the prior art, a placement of
silicone polymer composition in a fabric is not controlled to such
a degree so as to produce a product in accordance with the present
invention.
EXAMPLE 25: Description of Fabric Controlled Placement Through
Scanning Electron Microscope (SEM) Photomicrographs
[0358] FIGS. 13a, 13b and 13c were taken using a Cambridge 360
scanning electron microscope. The samples are cut using Teflon
coated razor blades, mounted on 1/2 inch diameter aluminum stubs,
and coated with a gold/palladium alloy.
[0359] FIG. 13a is a photomicrograph of the Tactel (Hot Coral)
fabric described in Example 23. The surface of the material has
been magnified 120 times and shows that the cured silicone polymer
impregnant is present as a thin film, or coating, or layer within
the material and envelopes at least a portion of the fibers. The
fiber bundles are somewhat distinguishable in the weave, but each
filament in the fiber bundles is not individually distinct.
[0360] The sample in FIG. 13b has been magnified 800 times and
shows the cross-section of a fiber bundle from the same Tactel in
FIG. 13a. The cured silicone polymer impregnant envelopes at least
a portion of the fibers. The interstices or void areas between
filaments in the region of the internal coating are mostly filled
or plugged by such impregnant. However, the web remains breathable
and because of the impregnant barrier is either water resistant or
waterproof.
[0361] FIG. 13c is the side of the fabric in FIG. 1 opposite from
which the silicone polymer impregnant was applied. The silicone
polymer impregnant is most readily apparent at the fiber bundle
interstices and not visible in the fiber bundles themselves.
[0362] FIG. 15a depicts a 330 denier cordura fiber, encapsulated
with a composite polymer, magnified 1950 times. The left side of
the picture is in normal scanning electron mode and the right side
of the picture is magnified 10 times in secondary electron
microscopy back scatter mode. The isolated rectangular box image in
the middle of the left side was exposed to destructive electron
beams isolated on the central opening in the center of the wrinkled
formation. The wrinkled film casing represents the composite
polymer (solid silicone and oxyethylated nylon) thin-film, this is
a direct result of the destructive electron exposure. The image on
the left side of the picture has surrounding fibers on the left and
right side of the isolated fiber, which also has some wrinkled
effects on the thin-film as a direct result of the destructive
electron analysis. The rectangular box on the upper side of the
picture was targeted for an elemental analysis. The electron beam
was targeted at the rectangular box with very low current (10 KV
and probe at 3.0 nA) to insure isolation of elemental signal from
any other area. FIG. 15b depicts the elemental graph of the
targeted region, which clearly shows the presence of the composite
polymer containing si or silicon. Combined, FIGS. 15a and 15b show
fiber encapsulation by the composite polymer.
[0363] FIG. 15c depicts a cut end of a filament illustrating a thin
film encapsulation in white. A crack was created in the filament
with a high temperature electron beam. This crack continues under
the surface of the thin film. The filament has been cut and the
thin film has been stretched or elasticized by the cutting of the
filament. The two arrows in the upper right corner show the
thickness or distance represented by the black box in the lower
right corner as 126 nm.
[0364] FIG. 15d depicts an isolated image on 330 Denier Cordura
single filament fiber processed with the micro-finish fiber coating
technology, magnified 5,720 times. The Bioengineered Comfort.TM.
polymer containing engineered protein and solid silicone was used
in the process with a moderate degree of shear. The image on top of
the fiber is an undispensed protein polymer which clearly
illustrates the presence of the protein after the micro-finish
fiber coating process. The surface morphology has very small
protein polymer particles encapsulated in the solid silicone
polymer and is homogeneously dispersed throughout the film system
on the fiber.
[0365] FIG. 15e is an image of a white nylon magnified 178 times.
The application side is shown at the bottom left hand corner of the
image. The upper portion of the image is the non-application side.
At the upper right corner is the intersection of the warp and fill
fiber bundles, where the polymer presence can clearly be seen on
the fibers. The internal layer of polymer that creates the liquid
barrier or resistant property can be seen along the bottom right
corner of the picture. This internal layer is a combination of
polymer filling some interstitial spaces and polymer "glueing"
together the fibers and filaments of the web.
[0366] FIG. 15f is a Tunneling Electron Microscopy (TEM) image of a
thin cross section of a filament encapsulated with polymer. The
lighter image on the lower side of the frame is a polyester
filament. The black spherical dots on the outer edge of the fiber
are extremely dense processed material. In this imaging technique,
the darker the image, the denser that specific material.
[0367] FIG. 15g depicts an individual filament shown in a split
screen format. The left hand image is showing the filament with
submicron metal particles dispersed in the processed film. The
right hand portion of the split screen is imaging the filament with
a technique known as secondary electron back scattering. The bright
particles are the same particles on the same fiber as seen in the
left side of the split screen. The difference is one of density,
the brighter metal particles are imaging density differential over
the underlying filament.
[0368] FIG. 15h depicts a nylon fabric magnified 419 times with
bright particle tracer images and a cross sectional image of a
nylon fabric. These bright particles are submicron metal particles
dispersed throughout the fabric in the processed film. The addition
of bright copper submicron particles in the polymer allows
secondary back scatter mode to illustrate the complete
encapsulation ability of the controlled placement technology. The
left side of the image is the performance side of the fabric which
is the non-application side of the polymer, but it is clear, with
the presence of the glowing brightness of the copper submicron
particles throughout the performance side of the fabric, that
controlled placement technology successfully encapsulates
completely around the fibers throughout the fabric structure. The
other clear unique feature of the controlled placement technology
is that each fiber is still independent. This differentiation
allows the controlled placement technology's processed fabrics to
retain exceptional hand and tactile quality, while still imparting
performance characteristics. On the left side of the fabric,
directly underneath the printed text "performance side", an
elemental analysis was conducted and the outcome of that analysis
is depicted in FIG. 15i. The result clearly shows a strong presence
of submicron copper particles.
[0369] In the next examples that involve accelerated weathering,
abrasion, water repellency, moisture penetration, and rain testing,
data is provided for a Tactel fabric identified as Deva Blue. The
fabric is 100% nylon, available from Arthur Kahn and identical in
composition, preparation, and enveloping specification to that of
the Hot Coral presented in previous examples.
EXAMPLE 26: Accelerated Weathering Test
[0370] The results of weathering upon a treated web of this
invention are shown in actual tested sample pieces comparing
original fabrics with embodiments of the enveloped fiber fabrics of
this invention.
[0371] In every case, the enveloped fiber fabric samples were found
to have significantly better weathering characteristics than the
original untreated fabrics as determined by accelerated weathering
tests. Even the reverse side (compared to the treated side) of an
enveloped fiber nylon fabric of the Tactel.RTM. type was improved
over the original fabric. In addition, the excellent "hand" of the
enveloped fiber fabric was found to have been maintained after the
accelerated weathering test.
[0372] The test performed conforms to each of the following
performance standards:
[0373] ASTM G-53 light/water exposure materials
[0374] ASTM D-4329 light/water exposure-plastics
[0375] General Motors Test spec TM-58-10
[0376] ISO 4892 Plastics exposure to lab light
[0377] The procedure used for the accelerated weathering testing
involved subjecting fabric samples to four hours of high-intensity
ultraviolet light, alternating continuously with four hours of
water condensation, wetting the fabric in the dark. This
alternating exposure (four hours on, four hours off) to
high-intensity ultraviolet light and water wetting, simulates
outdoor environmental conditions in a vastly accelerated manner,
quickly degrading unprotected dyes and fibers. The methods and
apparatus used for this test was a QUV Accelerated Weathering
Tester from The Q-Panel Company, 26200 First Street, Cleveland,
Ohio 44145.
[0378] The results obtained on some sample fabrics are expressed in
Table V. In this Table, results are expressed in the form of "A/B"
where A and B are numbers. The number "A" is the color rating on a
graduated scale from 0 to 10. The number 10 equals perfect
(original) condition where 0 equals a white color and a completely
faded fabric. The number "B" is the number of hours of weathering
transpiring when the number "A" rating was obtained.
5TABLE V Accelerated Weathering Testing COLOR RATING ORIGINAL
ENVELOPED REVERSE (RATING/HOURS) ORIGINAL FABRIC FABRIC SIDE 10 -
PERFECT FABRIC WEATHERED WEATHERED WEATHERED 0 = WHITE FADES OUT
TACTEL.degree. 3/159 8/159 After 159 hrs., enveloped Deva Blue
fabric significantly less 9-420-6-1 weathered than original; 10/0
original nearly white; enveloped fabric still light blue.
TACTEL.degree. 5/24 10/24 9/24 After 24 hrs., enveloped Hot Coral
fabric is significantly less 9-420-6-2 weathered than original, as
(AKA 18) was reversed side. 10/0
EXAMPLE 27: Abrasion Resistance Testing
[0379] The results of abrasion resisting testing clearly show that
enveloped fiber fabrics of this invention have superior wear
characteristics compared to the untreated original (starting)
fabrics. In most cases, the enveloped fiber fabric samples
underwent twice as many cycles as the untreated samples without
evidencing tearing in the samples. Such results can be explained by
theorizing that the envelopment with silicone polymer of the yarns
and fibers comprising a fabric, provides such treated yarns and
fibers with a lubricity agent so that abrasive action was minimized
and the integrity of the fabric was preserved significantly longer.
The anti-abrasion characteristics also applied to the minimized
effects of one fiber rubbing against another fiber, or of one yarn
against another yarn.
[0380] This experiment compared the abrasion resistance of
embodiments of the enveloped fiber fabrics of this invention with
untreated fabrics. The durability of each fabric test specimen was
determined by the Taber Abraser. Each specimen is abraded for the
number of cycles indicated. Comparisons were then made between the
enveloped fiber fabrics of the invention and untreated fabrics.
Specifically, this test method utilizes the Taber Abraser No. 174.
An important feature of this abrader was that its wheels traverse a
complete circle on the test specimen surface. Thus, the surface was
abraded at all possible angles relative to the weave or grain of
the specimen. Comparisons of the enveloped fiber fabric to the
untreated fabric were based upon a scale 0 through 10, where 0 was
a completely tom specimen, and 10 was the new (or starting)
sample.
[0381] Each test procedure used a single 7 inch diameter fiber
enveloped fabric specimen, and a single 7 inch diameter original
(untreated) fabric specimen. The procedure used was as follows:
[0382] 1. A test specimen of the fiber enveloped fabric with a 7
inch diameter was cut.
[0383] 2. An equally-sized specimen of control (untreated) fabric
was cut.
[0384] 3. The fabric specimen was mounted on the rotating wheel
securely and the clamps were screwed down.
[0385] 4. The counter was set.
[0386] 5. The vacuum power adjustment was set. (For this
experiment, vacuum was set at 80.)
[0387] 6. The abraser was started.
[0388] 7. At the procedurally specified number of revolutions, the
abraser was stopped and each fabric sample was rated at a value
between 0 and 10.
[0389] Illustrative results of the test on some sample fabrics are
shown in Table VI.
Abrasion Testing
Numeric Grade of Abrasion 0-10
[0390] 0- Total failure of fabric specimen. Fibers are torn
apart
[0391] 5- Fabric specimen is starting to tear. Fabric is noticeably
thinner
[0392] 10- Original unabraded fabric specimen
6TABLE VI SPECI- UNTREATED ENCAPSULATED MENS FABRIC FABRIC COMMENTS
Hot Coral 5 7 Untreated sample is Tactel 1,000 cyc. 1,000 cyc.
starting to tear, and enveloped sample was still intact. Deva Blue
4 7 Visible rips in untreat- Tactel 1,000 cyc. 1,000 cyc. ed
sample. Enveloped sample fibers were frayed.
EXAMPLE 28: Breathability Testing
[0393] This test procedure followed the Modified ASTM E96-8 test.
As shown by the results of this testing in the following Table, the
fiber enveloped fabrics of this invention were found to have high
breathability. This breathability was in excess of that needed to
remove the average value of several thousand grams of perspiration
generated daily by the human body. The results for the fiber
enveloped fabrics of this invention were generally superior to the
corresponding results measured under the same conditions for prior
art treated fabrics, such as the Gore-Tex.RTM. brand fabric.
[0394] Breathability of a fabric sample was determined by
accurately weighing the amount of water passing through such fabric
sample under carefully controlled temperature and relative humidity
conditions in an environmental chamber. The water weight loss from
a cup whose mouth is sealed with a fabric sample was expressed as
grams of water vapor per square meter of fabric per 24 hour
day.
[0395] In an attempt to more realistically simulate what is
actually occurring inside the apparel during exercise, a specially
designed test was performed to measure outward water vapor
transport (MVTR) in a "Bellows" effect. The test simulates the high
volumes of moisture and air that mix within a garment that pass
outward through it as air is drawn in resultant from activity. The
enveloped fabrics of this invention were found to provide increased
performance at a higher activity, or air exchange level than is
achievable with corresponding untreated fabrics.
[0396] The "Bellows" MVTR breathability test was run inside of a
controlled temperature/humidity chamber similar to the foregoing
cup test. However, instead of a standard cup, each fabric sample
was sealed over the open top of a special cup which was provided
with an air inlet aperture in its bottom, thereby allowing air to
be bubbled up through the sealed container at a controlled rate. A
check valve at the air inlet operation prevents backup or loss of
water from the container. The air bubbles passed upwardly through
the water and out through the fabric sample mounted sealingly
across the cup top along with the water vapor. Table VII
illustrates some representation results obtained.
7TABLE VII Moisture Vapor Transport (MVTR) FRABRIC MVTR.sup.(1)
Made by a Method od the Invention 13,600 Enveloped fiber fabric,
Hot Coral Tactel .RTM. Commercial Products 10,711
Gore-Tex.backslash.3-Ply Fabric Table Footnote: .sup.(1)MVTR here
references moisture vapor transport through a fabric sample as
measured by the "Bellows" test with air delivered to the bubbler at
2 to 4 psi air pressure, in an Environmental Chamber at 100 to
102.degree. F. and 38-42% relative humidity. MVTR is expressed as
grams of water per square meter of surface per 24 hour day.
EXAMPLE 29: Water Repellency: Spray Testing
[0397] Water repellency spray testing is carried out according to
AATCC Test Method 22-1974. The results of such testing show that
the fiber enveloped Tactel.RTM.-type fabrics of the invention show
excellent initial spray ratings initially, as do the original
untreated fabrics which have been treated with water repellent
chemicals such as fluorochemicals. Specifically, as the results
shown below demonstrate, after ten machine washes, the treated side
of a fiber enveloped fabric of the invention was found to remain
highly water repellent, while, on the reverse side thereof, the
original water repellency rating was found to have fallen
significantly. The water repellency spray rating on the untreated
fabric fell even more drastically. Excellent "hand" was retained
after the test. It is believed that pretreatment with a
fluorochemical having good water repellent properties can augment
and even synergistically coact with the silicone resin used to
produce fiber enveloped fabrics of this invention to produce
superior spray ratings in such a fiber. The results are shown in
Table VIII.
[0398] This test method is believed to be applicable to any textile
fabric, whether or not it has been given a water resistant or
water-repellent finish. The purpose of the test is to measure the
resistance of fabrics to wetting by measuring the water-repellent
efficiency of finishes applied to fabrics, particularly to plain
woven fabrics. The portability and simplicity of the instrument,
and the shortness and simplicity of the test procedure, make this
method of test especially suitable for mill production control
work. This test method is not intended, however, for use in
predicting the probable rain penetration resistance of fabrics,
since it does not measure penetration of water through the
fabric.
[0399] The results obtained with this test method are believed to
depend primarily on the resistance to wetting, or the water
repellency, of the fibers and yarns comprising a fabric, and not
upon the construction of the fabric. This test involves spraying
water against the taut surface of a test fabric specimen under
controlled conditions which produce a wetted pattern whose size
depends on the relative water repellency of the fabric. Evaluation
is accomplished by comparing the wetted pattern with pictures on a
standard chart. The methods and apparatus and materials employed
for this test were an AATCC Spray Tester, a beaker, distilled
water, and the specimen fabrics.
[0400] The procedure followed for this test was as follows: a test
specimen, which had been conditioned as procedurally directed, was
fastened securely in a 15.2 cm (6") metal hoop so that it presented
a smooth wrinklefree surface. The hoop was then placed on the stand
of the tester so that the fabric was uppermost in such a position
that the center of the spray pattern coincided with the center of
the hoop. In the case of twills, gabardines, piques or fabrics of
similar ribbed construction, the hoop was placed on the stand in
such a way that the ribs were diagonal to the flow of water running
off the fabric specimen.
[0401] 250 milliliters (ml) of distilled water at 27.degree.
C..+-.1.degree. C. (80.degree. F..+-.2.degree. F.) was poured into
the funnel of the tester and allowed to spray onto the test
specimen, which took approximately 25 to 30 seconds. Upon
completion of the spraying period, the hoop was taken by one edge
and the opposite edge tapped smartly once against a solid object,
with the fabric facing the object. The hoop was then rotated 180
degrees and then tapped once more on the location previously
held.
[0402] The procedure and methods and apparatus of this test were
slightly modified from the specifications, as follows:
[0403] 1. The spray nozzle holes were slightly larger than
specified, but the flow rate of the nozzle was 250 ml/30 sec., as
required.
[0404] 2. The number of taps of the hoop was two instead of
one.
[0405] For each wash test, a fabric sample was washed using a warm
wash/cold rinse cycle with one cup of Tide.RTM. detergent and dried
at a hot/dry cycle in a dryer, unless otherwise indicated. The test
results were evaluated by comparing the wet or spotted pattern on
the fabric sample after tapping the hoop with the standard rating
chart. Results produced surface wetting, with no water completely
soaking through the test fabric sample. The numbers were ratings
based upon the standard chart. Such values are thus subjective
deductions by an experienced experimenter.
8TABLE VIII Spray Test Results ORIGINAL FABRIC ENVELOPED FIBER
FABRIC OF THE INVENTION Tactel .RTM. Initial After 5 Washes After
10 Washes Color After 4 Enveloped Reverse Env. Reverse Env. Reverse
& Number Initial Washes Side Side Side Side Side Side Deva Blue
100 10 90 100 90 70 80 50 9-420-6-1 Hot Coral 100 30 90 100 70 55
70 30 9-420-6-2 Gold Tactel 100 100 90 90 90 90 90 90 8-100-1
EXAMPLE 30: Moisture Penetration Test
[0406] The results shown in the Table below demonstrate that all of
the fiber enveloped fabrics of this invention test were
significantly better than the original untreated fabrics with
regard to resisting the penetration of water under the test
conditions used after the test, the "hand" of the tested fabric
samples remained excellent
[0407] The purpose of this test was to evaluate how well a fabric
stands up to wetness under continuous pressure, such as kneeling on
the ground, or sitting in a wet chairlift, for a period of 30
minutes. This test involves placing both a fabric sample and a
standard blotter sample on top of a water container which contains
700 ml of tap water. The fabric sample and the blotter sample are
each then subjected to a continuous pressure of 87 lbs. distributed
evenly over 100 square inches of surface area for a period of 30
minutes. After this time, a visual inspection of the fabric is made
for any water penetration, and the paper blotter is weighed to
detect water gain or penetration.
[0408] The methods and apparatus employed for each such test was
one 20 inch diameter aluminum pan, one 87 lbs. weight distributed
evenly over 100 square inches of fabric, one paper blotter, 700 ml
water, miscellaneous fabric scraps for cushioning and the test
fabric sample pieces.
9 Paper blotter dry weight: 4.7 gm Total weight applied to fabric:
87 lbs. Pressure evenly distributed over 100 sq. in. surface area
of: Pressure: 0.87 lbs./sq. in.
[0409] The procedure observed for this test was as follows:
[0410] 1. 700 ml tap water was placed in the round pan.
[0411] 2. The fabric sample was placed with one side facing the
water.
[0412] 3. One piece of dry blotter paper was placed over the fabric
to cover the pan.
[0413] 4. Scrap fabric was placed over the blotter paper to cushion
the weight.
[0414] 5. The 87 lb. weight was distributed evenly over the
100-square-inch area.
[0415] 6. This assembly was left undisturbed for 30 minutes.
[0416] 7. After this time period, the visual results were
recorded.
10TABLE IX Fiber Enveloped Fabric of the Invention FABRIC ENVELOPED
SIDE OF NON-ENVELOPED SIDE SAMPLE AND FABRIC OF FABRIC CONTROL
THICKNESS FACING WATER FACING WATER FABRIC Deva Blue No water
penetration No water penetration through Failure-total Tactel .RTM.
through the fabric. No the fabric. No visible water saturation of
fabric 0.009 microns visible water spots. spots. Paper weight = 4.7
gm and blotter. Paper weight = 4.7 gm Water gain = 0.0 gm Water
gain = 0.0 gm
EXAMPLE 31: Rain Test
[0417] In this testing, the rain test procedure of AATCC Method
35-1985 was followed.
[0418] The rain test results obtained demonstrate the clear
superiority of the fiber enveloped fabric of the present invention
as compared to the original untreated fabric. The data in the Table
below shows that fiber enveloped fabrics pass this test by allowing
virtually no water to pass therethrough. This result is comparable
to the results obtained with higher cost so-called breathable
waterproof fabrics currently commercially available in the market.
In contrast, the original, untreated fabrics fail to pass this test
because they demonstrate complete saturation. The fiber enveloped
fabric samples retain excellent "hand" after the test.
[0419] The purpose and scope of this ASTM test is to evaluate
resistance of a fiber enveloped fabric to water under simulated
storm conditions. The test specifies that a test fabric is
stormproof if less than one gram of water is absorbed by blotter
paper with a shower head pressure of 3 feet exerted for 5 minutes.
This test method is applicable to any textile fabric, whether or
not it has a water repellent finish. It measures the resistance of
a fabric to the penetration of water by impact, and thus can be
used to predict the probably rain penetration resistance of a
fabric. The results obtained with this method of test depend on the
water repellency of the fibers and yarns in the fabric tested, and
on the construction of the fabric.
[0420] This test involves a test specimen backed by a pre-weighed
standard blotter. The assembly is sprayed with water for 5 minutes
under controlled conditions. The blotter then is separated and
weighted to determine the amount of water, if any, which has leaked
through the specimen fabric during the test and has been absorbed
by the blotter.
[0421] The methods and apparatus and materials employed in each
test were a modified rain tester, blotter paper, water at
80.degree. F..+-.2.degree. F., a laboratory balance, 8".times.8"
fabric specimens which had been pre-conditioned in an atmosphere of
65% (.+-.2%) relative humidity and 70.degree. F. (.+-.2.degree. F.)
for four hours before testing, and tape.
[0422] The procedure followed for this test was as follows:
[0423] 1. A 6".times.6" paper blotter was weighted to the nearest
0.1 gm and placed behind the test specimen.
[0424] 2. The test fabric with the paper blotter in registration
therewith was taped on the specimen holder.
[0425] 3. A tube in the rain tester was filled with water up to the
3 foot level. It was confirmed that water was flowing out of the
overflow tube which maintains the 3 foot column of water.
[0426] 4. The water spray distance from the tip of the nozzle to
the specimen holder was measured and adjusted to 12 inches.
[0427] 5. The specimen holder was left in place and the rain tester
was turned on for five minutes.
[0428] 6. After the test period, the paper blotter was removed and
reweighed to the nearest 0.1 gm.
[0429] The results of the test selected fabric samples are shown in
Table X.
11TABLE X Rain Test: Grams of Water Penetrating the Fabric ORIGINAL
AFTER 5 AFTER 10 MACHINE FABRIC SAMPLE NOT WASHED MACHINE WASHES
WASHES Hot Coral Tactel.degree. 0 0 0 Deva Blue Tactel.degree. 0 0
0 Prior Art Treated Fabrics Ultrex.degree. 0 -- 0.1
Gore-Text.degree. 0 0 -- Original Fabrics-Water Repellant Chemicals
Only, No Encapsulation Hot Coral Tactel/Failed-saturated; Deva Blue
Tactel/Failed-saturated
[0430] It should be understood, of course, that the foregoing
relates only to preferred embodiments of the present invention and
that numerous modifications or alterations may be made therein
without departing from the spirit and the scope of the invention as
set forth in the appended claims.
* * * * *