U.S. patent application number 13/827358 was filed with the patent office on 2013-08-08 for elastic composite film and composite fabric and production process thereof.
This patent application is currently assigned to W. L. Gore & Associates, Co., Ltd.. The applicant listed for this patent is W. L. Gore & Associates, Co., Ltd.. Invention is credited to Takashi Imai.
Application Number | 20130202875 13/827358 |
Document ID | / |
Family ID | 36777369 |
Filed Date | 2013-08-08 |
United States Patent
Application |
20130202875 |
Kind Code |
A1 |
Imai; Takashi |
August 8, 2013 |
Elastic Composite Film and Composite Fabric and Production Process
Thereof
Abstract
An elastic composite film provided with a sintered ePTFE film
and an elastomeric resin layer, produced by continuously forming
the elastomeric resin layer on at least one side of the sintered
ePTFE film, continuously elongating the resulting multilayer film
at less than the yield point of the expanded, sintered, porous film
and at an elongation factor of 1.3 times or more in the biaxial
directions, or in the uniaxial direction without contracting in the
direction perpendicular to the direction of elongation, and
relaxing the resulting elongated multilayer film, wherein when the
composite film is elongated by 10% in the longitudinal and/or
transverse direction, the tensile stress of the composite film is
2.5 N/15 mm or less, and/or the elongation percentage of the
composite film in the longitudinal and/or transverse direction is
30% or more and the elongation recovery rate is 70% or more.
Inventors: |
Imai; Takashi; (Okayama,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
W. L. Gore & Associates, Co., Ltd.; |
Tokyo |
|
JP |
|
|
Assignee: |
W. L. Gore & Associates, Co.,
Ltd.
Tokyo
JP
|
Family ID: |
36777369 |
Appl. No.: |
13/827358 |
Filed: |
March 14, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11814952 |
Feb 14, 2008 |
|
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PCT/JP2006/302201 |
Feb 2, 2006 |
|
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13827358 |
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Current U.S.
Class: |
428/319.3 ;
156/229; 264/134 |
Current CPC
Class: |
Y10T 442/601 20150401;
B32B 2307/724 20130101; B32B 2307/7265 20130101; B32B 38/0012
20130101; B32B 27/322 20130101; B32B 27/40 20130101; B32B 37/144
20130101; B32B 5/02 20130101; B32B 2327/18 20130101; B32B 2038/0028
20130101; B29C 55/005 20130101; Y10T 442/3016 20150401; Y10T 442/40
20150401; A41D 31/102 20190201; B32B 5/245 20130101; B32B 27/08
20130101; Y10T 428/249991 20150401; A41D 31/185 20190201 |
Class at
Publication: |
428/319.3 ;
264/134; 156/229 |
International
Class: |
B32B 5/24 20060101
B32B005/24; B32B 38/00 20060101 B32B038/00; B29C 55/00 20060101
B29C055/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 2, 2005 |
JP |
2005-026268 |
Claims
1. An elastic composite film provided with an expanded, sintered,
porous film substantially consisting of polytetrafluoroethylene and
an elastomeric resin layer formed on at least one side of the
expanded, sintered, porous film; wherein, when the composite film
is elongated by 10% in the longitudinal and/or transverse
direction, the tensile stress of the composite film is 2.5 N/15 mm
or less, and/or the elongation percentage of the composite film in
the longitudinal and/or transverse direction is 30% or more and the
elongation recovery rate is 70% or more.
2. The elastic composite film according to claim 1, wherein the
elastomeric resin layer contains a polyurethane resin.
3. An elastic composite fabric comprising an elastic cloth
laminated onto one or both sides of a composite film provided with
an expanded, sintered, porous film substantially consisting of
polytetrafluoroethylene and an elastomeric resin layer formed on at
least one side of the expanded, sintered, porous film; wherein,
when the composite fabric is elongated by 10% in the longitudinal
and/or transverse direction, the tensile stress of the composite
fabric is 2.5 N/15 mm or less, and/or the elongation percentage of
the composite fabric in the longitudinal and/or transverse
direction is 30% or more and the elongation recovery rate is 70% or
more.
4. The elastic composite fabric according to claim 3, wherein the
elastomeric resin layer contains a polyurethane resin.
5. A textile product comprising an elastic composite fabric
according to claim 3.
6.-10. (canceled)
11. An elastic composite film provided with an expanded, sintered,
porous film and an elastomeric layer produced by continuously
forming an elastomeric layer on at least one side of an expanded,
sintered, porous film substantially consisting of
polytetrafluoroethylene, continuously elongating the resulting
multilayer film at less than the yield point of the expanded,
sintered, porous film and at an elongation factor of 1.3 times or
more in the biaxial directions, or in the uniaxial direction
without contracting in the direction perpendicular to the direction
of elongation, and relaxing the resulting elongated multilayer
film; wherein, when the composite film is elongated by 10% in the
longitudinal and/or transverse direction, the tensile stress of the
composite film is 2.5 N/15 mm or less, and/or the elongation
percentage of the composite film in the longitudinal and/or
transverse direction is 30% or more and the elongation recovery
rate is 70% or more.
12. A composite fabric provided with an expanded, sintered, porous
film, an elastomeric resin layer and an elastic cloth, produced by
a process comprising the steps of: (1) continuously forming the
elastomeric resin layer on at least one side of the expanded,
sintered, porous film substantially consisting of
polytetrafluoroethylene; (2) continuously laminating the elastic
cloth onto one or both sides of the multilayer film obtained in (1)
above, and continuously elongating the laminated fabric obtained in
the lamination step at less than the yield point of the expanded,
sintered, porous film and at an elongation factor of 1.3 times or
more in the biaxial directions, or in the uniaxial direction
without contracting in the direction perpendicular to the direction
of elongation; or (2') continuously elongating the multilayer film
obtained in (1) above at less than the yield point of the expanded,
sintered, porous film and at an elongation factor of 1.3 times or
more in the biaxial directions, or in the uniaxial direction
without contracting in the direction perpendicular to the direction
of elongation, and continuously laminating the elastic cloth onto
one or both sides of the elongated multilayer film obtained the
elongation step; and, (3) relaxing the elongated laminated fabric
obtained in (2) or (2') above; wherein, the tensile stress of the
composite fabric when elongated by 10% in the longitudinal and/or
transverse direction is 2.5 N/15 mm or less, and/or the elongation
percentage of the composite fabric in the longitudinal and/or
transverse direction is 30% or more and the elongation recovery
rate is 70% or more.
13. A textile product comprising an elastic composite fabric
according to claim 4.
14.-19. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 11/814,952, filed Jul. 27, 2007, the entire contents of
which are expressly incorporated herein by reference in its
entirety.
TECHNICAL FIELD
[0002] The present invention relates to a composite film and a
composite fabric, comprising an expanded, sintered, porous
polytetrafluoroethylene (PTFE) film, having elastic properties, and
preferably having waterproof water vapor permeability, and
production processes thereof.
BACKGROUND ART
[0003] Although sintered, porous expanded polytetrafluoroethylene
(ePTFE) films and fabrics comprised of a laminate of such expanded,
sintered, porous PTFE film and cloth have been proposed and used
practically as waterproof, water-vapor-permeable films, they do not
have adequate elastic properties.
[0004] For example, Japanese Unexamined Patent Publication No.
51-30277 (see U.S. Pat. No. 3,953,566) discloses a technology for
obtaining an expanded, sintered, porous PTFE film having enhanced
strength such as tensile strength as a result of expanding and
increasing the porosity of a PTFE molded article, obtained by
injection-molding a PTFE powder-containing paste, at a temperature
equal to or below the crystal melting point of PTFE followed by
sintering for 5 seconds to 1 hour at a temperature equal to or
above the crystal melting point, such as a temperature of 350 to
370.degree. C.
[0005] In addition, Japanese Unexamined Patent Publication No.
55-7483 contains a description regarding a material in which an
elastomeric resin layer is formed on an expanded, sintered, porous
PTFE film. Although these Japanese Unexamined Patent Publications
Nos. 51-30277 and 55-7483 provide articles that can be preferably
used as clothing, it is not the object of either of these
publications to provide articles having elastic properties.
[0006] Japanese Unexamined Patent Publication No. 59-187845
discloses a method for imparting elastic properties by mechanically
elongating a composite film of a sintered, expanded
polytetrafluoroethylene (ePTFE) film and an elastomeric resin
layer, or a composite in which that composite film is laminated
with a cloth, beyond the yield point of the ePTFE at least by 5% or
more. The ePTFE film of Japanese Unexamined Patent Publication No.
59-187845 is considered to be an expanded, sintered, porous PTFE
film based on the description that it is given by the technology of
U.S. Pat. No. 3,953,566.
[0007] The examples in this Japanese Unexamined Patent Publication
No. 59-187845 describe that when a composite article of an ePTFE
film and an elastomeric resin having a width of 12 inches (and
length of 14 inches) is folded into a strip having a width of 1 to
1.25 inches and elongated two-fold (9-inch clamping interval
elongated to 18 inches) in the longitudinal direction with an
Instron tester, the sample width is necked to 3/8 to 1/2 inch. In
this method, two-fold elongation treatment is possible by necking
the sample during elongation treatment. Here, necking the width by
about 1/2 during two-fold elongation means that the sample was only
deformed in the direction of elongation without any substantial
change in the size (total area) of the sample. In the case of
having necked sample width during elongation, even if the tension
during elongation is released, wrinkles form in the direction of
elongation and the sample width only recovers to about 70 to 80% of
the width prior to elongation. Consequently, in the case of a
producing a product with this method, products can only be produced
having a width that is narrower than the width of the cloth used in
production, thereby increasing production cost. In addition, since
wrinkles form in the product, the appearance becomes poor. In
addition, in the case of having carried out elongation treatment in
the longitudinal direction while preventing necking in the
transverse direction under the conditions described above, due to
the use of a sintered ePTFE film, breakage occurs due to elongation
of roughly 20%, thereby making elongation treatment difficult.
[0008] Although elastic properties are not described in Japanese
Unexamined Patent Publication No. 59-187845, it is described in
Example 1 that the width is necked to about half at the stage of
having elongated two-fold, and that stretch recovery immediately
after is 64%. When the sample of Example 1 was actually prepared
and subjected to an elongation percentage test according to the
method described later, the sample width was necked to about half,
the elongation percentage was 25%, and the elongation recovery rate
was 65%, thus indicating that the sample cannot be said to have
adequate elastic properties.
[0009] In addition, Japanese Unexamined Patent Publication No.
61-137739 discloses an elastic, water-vapor-permeable, waterproof
film comprised of a composite film of an unsintered ePTFE film and
an elastomeric resin. Namely, a method is disclosed for expressing
elastic properties by impregnating and retaining an elastomeric
resin having hydrophilic groups into an unsintered ePTFE film.
Although the ePTFE film is unsintered, this is an essential
requirement for expressing elastic properties. Since the ePTFE film
is unsintered, a peel-off phenomenon of the surface layer occurs
caused by insufficient cohesive force in the direction of
thickness. It is described in this publication to the effect that,
if sintering is carried out to avoid this, ductility decreases due
to an absence of sliding between fibrils, and even if sintered
ePTFE is laminated with other lamination material, the elastic
properties of the partner lamination material, i.e. the other
material, is inhibited by the sintered ePTFE, thereby causing the
entire laminate to have hardly any elastic properties. In other
words, it is suggested that simply impregnating and retaining an
elastomeric resin in sintered ePTFE does not result in the
expression of stretchability.
[0010] Moreover, Japanese Unexamined Patent Publication No.
61-137739 also describes the coating of a resin having hydrophilic
groups on one or both sides for the purpose of avoiding the
peel-off phenomenon of the surface layer. In the case of coating on
one side, however, the lack of cohesive force on the uncoated side
becomes pronounced, and even if both sides are coated, if voids
remain within the ePTFE film, cohesive force is inadequate at those
portions. In order to completely prevent the peel-off phenomenon of
the surface layer, it is necessary to completely impregnate the
inside of the ePTFE film with a resin having hydrophilic groups,
which inevitably increases the thickness of the resin layer. Since
resins having hydrophilic groups are hydrophilic, although water
vapor permeability is expressed by dissolving moisture within the
resin, as long as the moisture migrates by diffusing through a
non-porous resin layer, the more water vapor permeability
decreases, the greater the thickness of the non-porous resin gets.
Although practical durability is inadequate unless unsintered ePTFE
films are completely impregnated with a resin having hydrophilic
groups to prevent the peel-off phenomenon of the surface layer and
the like, complete impregnation makes it difficult to express a
high level of water vapor permeability.
DISCLOSURE OF THE INVENTION
[0011] An object of the present invention is to solve the problem
of the prior art by providing an elastic composite film and a
composite fabric containing a sintered, porous expanded
polytetrafluoroethylene (ePTFE) film, and production processes
thereof. Preferably, an object of the present invention is to
provide a composite film and a composite fabric containing a
sintered, porous expanded polytetrafluoroethylene (ePTFE) film
having waterproof, water vapor permeability, and production
processes thereof. In addition, another object of the present
invention is to provide a textile product containing this elastic
composite fabric.
[0012] One aspect of the present invention relates to an elastic
composite film provided with an expanded, sintered, porous film
substantially consisting of polytetrafluoroethylene and an
elastomeric resin layer formed on at least one side of the
expanded, sintered, porous film; wherein, when the composite film
is elongated by 10% in the longitudinal and/or transverse
direction, the tensile stress of the composite film is 2.5 N/15 mm
or less, and/or the elongation percentage of the composite film in
the longitudinal and/or transverse direction is 30% or more and the
elongation recovery rate is 70% or more. Furthermore, the
elastomeric resin layer preferably contains a polyurethane
resin.
[0013] Another aspect of the present invention relates to an
elastic composite fabric comprising an elastic cloth laminated onto
one or both sides of a composite film provided with an expanded,
sintered, porous film substantially consisting of
polytetrafluoroethylene and an elastomeric resin layer formed on
one or both sides of the expanded, sintered, porous film; wherein,
when the composite fabric is elongated by 10% in the longitudinal
and/or transverse direction, the tensile stress of the composite
fabric is 2.5 N/15 mm or less, and/or the elongation percentage of
the composite fabric in the longitudinal and/or transverse
direction is 30% or more and the elongation recovery rate is 70% or
more. Furthermore, the elastomeric resin layer preferably contains
a polyurethane resin.
[0014] Another aspect of the present invention relates to a textile
product comprising an elastic composite fabric comprising an
elastic cloth laminated onto one or both sides of a composite film
provided with an expanded, sintered, porous film substantially
consisting of polytetrafluoroethylene and an elastomeric resin
layer formed on one or both sides of the expanded, sintered, porous
film; wherein, when the composite fabric is elongated by 10% in the
longitudinal and/or transverse direction, the tensile stress of the
composite fabric is 2.5 N/15 mm or less, and/or the elongation
percentage of the composite fabric in the longitudinal and/or
transverse direction is 30% or more and the elongation recovery
rate is 70% or more.
[0015] Another aspect of the present invention relates to a process
for continuously producing an elastic composite film provided with
an expanded, sintered, porous film substantially consisting of
polytetrafluoroethylene and an elastomeric resin layer formed on
one or both sides of the expanded, sintered, porous film,
comprising the steps of:
[0016] (1) continuously forming the elastomeric resin layer on at
least one side of the expanded, sintered, porous film;
[0017] (2) continuously elongating the multilayer film obtained in
(1) above at less than the yield point of the expanded, sintered,
porous film and at an elongation factor of 1.3 times or more in the
biaxial directions, or in the uniaxial direction without
contracting in the direction perpendicular to the direction of
elongation; and
[0018] (3) relaxing the elongated multilayer film obtained in (2)
above.
[0019] In this production process of an elastic composite film, the
elongation step is preferably carried out under heating conditions
of 100 to 200.degree. C., and preferably at an elongation rate of
5%/second or more. In addition, the relaxation step is preferably
carried out under conditions of 100.degree. C. or lower.
[0020] Another aspect of the present invention relates to a process
for continuously producing an elastic composite fabric comprising
an elastic cloth laminated onto at least one side of a composite
film provided with an expanded, sintered, porous film substantially
consisting of polytetrafluoroethylene and an elastomeric resin
layer formed on one or both sides of the expanded, sintered, porous
film, comprising the steps of:
[0021] (1) continuously forming the elastomeric resin layer on at
least one side of the expanded, sintered, porous film;
[0022] (2) continuously laminating the elastic cloth onto one or
both sides of the multilayer film obtained in (1) above, and
continuously elongating the laminated fabric obtained in the
lamination step at less than the yield point of the expanded,
sintered, porous film and at an elongation factor of 1.3 times or
more in the biaxial directions, or in the uniaxial direction
without contracting in the direction perpendicular to the direction
of elongation; or
[0023] (2') continuously elongating the multilayer film obtained in
(1) above at less than the yield point of the expanded, sintered,
porous film and at an elongation factor of 1.3 times or more in the
biaxial directions, or in the uniaxial direction without
contracting in the direction perpendicular to the direction of
elongation, and continuously laminating the elastic cloth onto one
or both sides of the elongated laminated film obtained the
elongation step; and,
[0024] (3) relaxing the elongated laminated fabric obtained in (2)
or (2') above.
[0025] In this production process of an elastic composite fabric,
the elongation step is preferably carried out under heating
conditions of 100 to 200.degree. C., and preferably at an
elongation rate of 5%/second or more. In addition, the relaxation
step is preferably carried out under conditions of 100.degree. C.
or lower.
[0026] Another aspect of the present invention relates to an
elastic composite film provided with an expanded, sintered, porous
film and an elastomeric layer produced by continuously forming an
elastomeric layer on at least one side of an expanded, sintered,
porous film substantially consisting of polytetrafluoroethylene,
continuously elongating the resulting multilayer film at less than
the yield point of the expanded, sintered, porous film and at an
elongation factor of 1.3 times or more in the biaxial directions,
or in the uniaxial direction without contracting in the direction
perpendicular to the direction of elongation, and relaxing the
resulting elongated multilayer film; wherein, when the composite
film is elongated by 10% in the longitudinal and/or transverse, the
tensile stress of the composite film direction is 2.5 N/15 mm or
less, and/or the elongation percentage of the composite film in the
longitudinal and/or transverse direction is 30% or more and the
elongation recovery rate is 70% or more.
[0027] Still another aspect of the present invention relates to a
composite fabric provided with an expanded, sintered, porous film,
an elastomeric resin layer and an elastic cloth produced by a
process comprising the steps of:
[0028] (1) continuously forming the elastomeric resin layer on at
least one side of the expanded, sintered, porous film substantially
consisting of polytetrafluoroethylene;
[0029] (2) continuously laminating the elastic cloth onto one or
both sides of the multilayer film obtained in (1) above, and
continuously elongating the laminated fabric obtained in the
lamination step at less than the yield point of the expanded,
sintered, porous film and at an elongation factor of 1.3 times or
more in the biaxial directions, or in the uniaxial direction
without contracting in the direction perpendicular to the direction
of elongation; or
[0030] (2') continuously elongating the multilayer film obtained in
(1) above at less than the yield point of the expanded, sintered,
porous film and at an elongation factor of 1.3 times or more in the
biaxial directions, or in the uniaxial direction without
contracting in the direction perpendicular to the direction of
elongation, and continuously laminating the elastic cloth onto one
or both sides of the elongated multilayer film obtained the
elongation step; and,
[0031] (3) relaxing the elongated laminated fabric obtained in (2)
or (2') above; wherein,
[0032] the tensile stress of the composite fabric when elongated by
10% in the longitudinal and/or transverse direction is 2.5 N/15 mm
or less, and/or the elongation percentage of the composite fabric
in the longitudinal and/or transverse direction is 30% or more and
the elongation recovery rate is 70% or more.
[0033] According to the present invention, a composite film, a
composite fabric and a textile product having superior elongation
and elongation recovery, as well as waterproof water vapor
permeability in a preferable aspect thereof are provided. According
to a preferable aspect, since a sintered, porous expanded
polytetrafluoroethylene (ePTFE) film is used for a base material,
practical durability is obtained without requiring an elastomeric
resin to be completely impregnated in the ePTFE film, thereby
providing a composite film, composite fabric and textile product
having high water vapor permeability. In addition, according to the
present invention, production processes of the composite film and
composite fabric are provided. According to preferable aspects
thereof, as a result of treating at an elongation treatment
temperature and elongation treatment rate within specific ranges
thereof, production processes are provided that allow a composite
film and composite fabric having superior elongation and elongation
recovery to be advantageously obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is an explanatory drawing showing the infrared
absorption spectra of ePTFE films.
[0035] FIG. 2 is an explanatory drawing showing an electron
micrograph of the surface of a sintered ePTFE film prior to
elongation treatment.
[0036] FIG. 3 is an explanatory drawing showing the effect of
elongation rate during elongation treatment of composite films of
the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0037] The elastic composite film of the present invention is a
composite film provided with an expanded, sintered, porous film
substantially consisting of polytetrafluoroethylene and an
elastomeric resin layer formed on at least one side of the
expanded, sintered, porous film; wherein, when the composite film
is elongated by 10% in the longitudinal and/or transverse
direction, the tensile stress of the composite film is 2.5. N/15 mm
or less, and/or the elongation percentage of the composite film in
the longitudinal and/or transverse direction is 30% or more and the
elongation recovery rate is 70% or more.
[0038] Although the expanded, sintered, porous (sintered ePTFE)
film substantially consisting of polytetrafluoroethylene in the
present invention is obtained by drawing a polytetrafluoroethylene
(PTFE) film and heating for 5 seconds to 1 hour at a temperature
equal to or higher than the melting point, such as at a temperature
of 350 to 370.degree. C., this sintered ePTFE film has high
porosity allowing the obtaining of high water vapor permeability,
has superior durability without causing a peel-off of the surface
layer, has flexibility, has extremely potent hydrophobicity, and
has superior chemical and heat resistance.
[0039] Furthermore, modified PTFE obtained by copolymerizing
tetrafluoroethylene-hexafluoropropylene copolymer (FEP),
tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA) or the like,
and mixed PTFE containing up to about 20% by weight of inorganic
materials or organic materials are included in the PTFE of the
present invention.
[0040] Sintered ePTFE films demonstrate amorphous absorption by
PTFE as a result of sintering at 780 cm.sup.-1 in the case of
measuring infrared absorption using an infrared spectrophotometer
as described in, for example, "Comparative Quantitative Study on
the Crystallinity of Poly(tetrafluoroethylene) including Raman,
Infrared and 19F Nuclear Magnetic Resonance Spectroscopy", R. J.
Lehnert, Polymer, Vol. 38, No. 7, p. 1521-1535 (1997)".
[0041] For example, absorption is confirmed at 780 cm.sup.-1 in the
case of having measured infrared absorption of a sintered ePTFE
film surface by ATR (using KRS-5 for the solute, at an incident
angle of 45 degrees, a resolution of 4 cm.sup.-1 and 20 scanning
cycles) using the "Paragon 1000" infrared spectrophotometer
manufactured by Perkin-Elmer. As shown by the spectra of FIG. 1,
although there is no absorption observed at 780 cm.sup.-1 in the
case of an unsintered ePTFE film, absorption is confirmed for a
sintered ePTFE film. In the case an elastomeric resin layer is
formed on one side of an ePTFE film, when the ePTFE film side is
measured and an elastomeric resin is formed on both sides of the
ePTFE film, the ePTFE film side is affixed with adhesive tape and
the like to the elastomeric resin layer and then peeled off the
tape followed by measuring the exposed ePTFE film.
[0042] In addition, sintering may also be confirmed by using a
differential scanning calorimeter (DSC). For example, differences
in melting points were explained by the degree of sintering as
measured with a DSC at the commemorative lecture on the 50th
anniversary of the discovery of PTFE presented by Shimizu in
Toronto in July 1988. It was demonstrated that melting peaks are
observed for unsintered ePTFE at 345-347.degree. C., for
partially-sintered ePTFE at 330 to 340.degree. C. and for
completely sintered ePTFE at 327.degree. C., and evaluations can
also be made by DSC in the case of obtaining only the PTFE portion
as a sample. Furthermore, the sintered ePTFE composed of
polytetrafluoroethylene in the present invention also contained
ePTFE in a partially-sintered state. Partially-sintered ePTFE is
obtained by heat treating for 5 minutes to 1 hour at a temperature
equal to or higher than the melting point (327.degree. C.) of PTFE.
In other words, this refers to sintering by heat treating at a
temperature equal to or higher than the melting point of PTFE.
[0043] The maximum pore diameter of the sintered ePTFE film is 0.01
to 10 .mu.m, and preferably 0.1 to 1 .mu.m. If the maximum pore
diameter of the sintered ePTFE film is less than 0.01 .mu.m, there
are difficulties in manufacturing the film, while conversely if the
maximum pore diameter exceeds 10 .mu.m, in addition to the water
vapor permeability of the film decreasing, since film strength
becomes weak, it becomes difficult to handle the film in the
lamination and other subsequent steps, thereby making this
undesirable. Furthermore, maximum pore diameter is determined
according to the measurement method defined in ASTM F-316.
[0044] In addition, the porosity of the sintered ePTFE film is 50
to 98% and preferably 60 to 95%. If the porosity of the sintered
ePTFE film is less than 50%, water vapor permeability decreases,
while if the porosity exceeds 98%, the strength of the film
decreases. Furthermore, porosity is determined by calculating
according to the following equation (1) from the apparent density
(p) as measured in compliance with the method for measuring
apparent density defined in JIS K 6885.
Porosity (%)=(2.2-.rho.)/2.2.times.100 (1)
[0045] The suitable thickness of the sintered ePTFE film is 7 to
300 .mu.m, and preferably 10 to 100 .mu.m. If the thickness of the
sintered ePTFE film is less than 7 .mu.m, problems occur with
handling during production, while if the thickness exceeds 300
.mu.m, the flexibility of the film is impaired and water vapor
permeability ends up decreasing. Film thickness is measured
according to the mean thickness as measured with a dial gauge (as
measured in the absence of a load other than the spring load of the
main unit using a dial thickness gauge having precision of 1/1000
mm manufactured by Teclock Corp.).
[0046] A sintered ePTFE film coated with a water-repellent and/or
oil-repellent polymer on the surfaces of the pores thereof as
necessary is also included in the sintered ePTFE film in the
present invention. In this case, examples of such polymers include
polymers having a fluorine-containing side chain. A detailed
description of such polymers and methods for compounding such
polymers with sintered ePTFE films are disclosed in, for example,
WO 94/22928.
[0047] A fluorine-containing polymer obtained by polymerizing a
fluoroalkyl acrylate and/or fluoroalkyl methacrylate (in which the
fluoroalkyl portion preferably has 6 to 16 carbon atoms)
represented by the following general formula (I):
##STR00001##
(wherein, n represents an integer of 3 to 13 and R represents a
hydrogen atom or a methyl group) can be preferably used for the
coating polymer. In order to coat the pores of a sintered ePTFE
film using this polymer, an aqueous microemulsion (having a mean
particle diameter of 0.01 to 0.5 .mu.m) is formed using a fluorine
surfactant (such as ammonium perfluorooctanate) followed by
impregnating this into the pores of the sintered ePTFE film and
heating. As a result, water and the fluorine surfactant are removed
and the fluorine-containing polymer melts causing the surface of
the pores of the sintered ePTFE film to be coated, thereby allowing
the obtaining of a sintered ePTFE film maintaining continuous pores
and having superior water repellency and oil repellency. In
addition, examples of other polymers that can be used include "AF
Polymer" (Dupont Corp.) and "Cytop" (Asahi Glass Co., Ltd.). In
order to coat these polymers onto the surfaces of pores of a
sintered ePTFE film, these polymers are dissolved in an inert
solvent such as "Fluorinate" (Sumitomo 3M Ltd.) followed by
impregnating into the sintered ePTFE film and evaporating off the
solvent. As a result of coating the surfaces of the pores of the
sintered ePTFE film with the aforementioned organic polymers, it
becomes difficult for contaminants to penetrate inside the sintered
ePTFE film when the sintered ePTFE film is contaminated by various
contaminants, thereby making it possible to prevent deterioration
of the hydrophobicity of the sintered ePTFE film.
[0048] The elastic composite film in the present invention has a
layer of an elastomeric resin formed in the form of a coating film
on at least one side of this sintered ePTFE film. Although silicone
resin, fluorine rubber, NBR, epichlorhydrin, synthetic rubber such
as EPDM, natural rubber, polyester resin, polyurethane resin and
other elastic resins are suitably used for the elastomeric resin,
in the case of using in applications requiring heat resistance,
silicone resin, fluorine rubber and the like are preferable. In
addition, from the viewpoint of water vapor permeability, polymer
materials having hydrophilic groups such as hydroxyl, carboxyl,
sulfonic acid or amino acid groups in the form of water-swellable,
water-insoluble and water-vapor permeable resins are used
preferably. Although specific examples thereof include at least
partially crosslinked hydrophilic polymers such as polyvinyl
alcohol, cellulose acetate and cellulose nitrate as well as
hydrophilic polyurethane resins, hydrophilic polyurethane resins
are particularly preferable in consideration of factors such as
chemical resistance, processability and water vapor permeability.
Furthermore, two or more types of the aforementioned resins may be
used as a mixture, or they may be mixed with inorganic or organic
fillers for the purpose of, for example, improving durability or
imparting antistatic properties.
[0049] Examples of hydrophilic polyurethane resins used include
polyester-based and polyether-based polyurethane and prepolymers
containing hydrophilic groups such as hydroxyl, amino, carboxyl,
sulfonic acid or oxyethylene groups, and diisocyanates or
triisocyanates having two or more isocyanate groups or adducts
thereof can be used alone or in the form of a mixture as a
crosslinking agent for adjusting the melting point (softening
point) of the resin. In addition, dipolyols, tripolyols, diamines
or triamines having two or more functional groups can be used as
curing agents for prepolymers having an isocyanate terminal. Two
functional groups are preferable to three functional groups for
maintaining a high level of water vapor permeability.
[0050] The thickness of the elastomeric resin layer of the elastic
composite film in the present invention is preferably 5 to 500
.mu.m and more preferably 10 to 300 .mu.m.
[0051] If the thickness of the elastomeric resin layer is less than
5 .mu.m, the stretch recovery of the elastic composite film becomes
inadequate, while if the thickness exceeds 300 .mu.m, the elastic
composite film becomes hard and heavy. In the case of using the
elastic composite film in applications requiring water vapor
permeability, the thickness of the elastomeric resin layer is
preferably 5 to 100 .mu.m and more preferably 10 to 70 .mu.m. If
the thickness of the elastomeric resin layer is less than 5 .mu.m,
the stretch recovery of the elastic composite film becomes
inadequate, while if the thickness exceeds 100 .mu.m, water vapor
permeability becomes inadequate.
[0052] In addition, the elastomeric resin layer formed on at least
one side of the sintered ePTFE film preferably partially penetrates
inside the sintered ePTFE film in terms of being able to prevent
the peel-off of the elastomeric resin layer and increasing
durability. In the case of using a water vapor-permeable resin for
the elastomeric resin, the thickness of the portion of the water
vapor-permeable resin that penetrates inside the sintered ePTFE
film is preferably 3 to 30 .mu.m and most preferably 5 to 20 .mu.m
from the viewpoints of water vapor permeability, softness (texture)
and durability. If the thickness is less than 3 .mu.m, durability
becomes inadequate in terms of practical use, while if the
thickness exceeds 30 .mu.m, water vapor permeability becomes
excessively low. Furthermore, the thickness of polyurethane resin
layers is determined by visually measuring the average thickness
using an electron micrograph scale (scale used to represent length)
from a cross-sectional electron micrograph (1000 to
3000.times.).
[0053] In the case of using the elastic composite film in the
present invention in applications requiring water vapor
permeability such as textile products, the water vapor permeability
thereof is preferably 2000 to 100000 g/m.sup.224 hr and more
preferably 3000 to 70000 g/m.sup.224 hr. Furthermore, water vapor
permeability refers to the value obtained by converting a measured
value obtained according to method B-2 defined in JIS L 1099 to the
value for 24 hours.
[0054] In the elastic composite film in the present invention,
layers of an elastomeric resin may be formed in the form of a
coating on both sides of the sintered ePTFE film. In this case, the
previously described elastomeric resins can be used, and the same
elastomeric resin may be used on both sides or different
elastomeric resins may be used on each side according to the
application.
[0055] The elastic composite film in the present invention is
characterized by the tensile stress when elongated by 10%, in the
longitudinal direction and/or transverse direction of the composite
film being 2.5 N/15 mm or less, and/or the elongation percentage in
the longitudinal direction and/or transverse direction of the
composite film being 30% or more and the elongation recovery rate
being 70% or more. Namely, the elastic composite film in the
present invention satisfies at least one of the requirements
consisting of the tensile stress when elongated by 10% being 2.5
N/15 mm or less, the elongation percentage being 30% or more, and
the elongation recovery rate being 70% or more.
[0056] A composite film that satisfies all of the ranges of tensile
stress, elongation percentage and elongation recovery rate is most
preferable in order to achieve practical elastic properties.
Depending on the case, elongation percentage and elongation
recovery rate may be within the prescribed ranges, while tensile
stress when elongated by 10% may be outside the aforementioned
range. In addition, the tensile stress when elongated by 10% may be
within the aforementioned range, while the elongation percentage
and elongation recovery rate may be outside the prescribed ranges.
The prescribed requirements are satisfied in at least the
longitudinal direction or transverse direction of the composite
film.
[0057] With respect to elongation percentage and elongation
recovery rate, a composite film in which the elongation percentage
35% or more and the elongation recovery rate is 80% or more is more
preferable, while a composite film in which the elongation
percentage is 40% or more and the elongation recovery rate is 90%
or more is particularly preferable, in terms of demonstrating more
superior elastic properties. Furthermore, elongation percentage was
determined by measuring elongation percentage after applying a 300
g load for 1 minute in compliance with method B defined in JIS L
1096, while elongation recovery rate was measured by using a time
of 1 minute for the time elapsed after removing the load in
compliance with method B-1 defined in JIS L 1096.
[0058] With respect to the tensile stress of the elastic composite
film of the present invention when elongated by 10%, a composite
film in which the tensile stress is 2 N/15 mm or less is more
preferable, while a composite film in which the tensile stress is
1.5 N/15 mm or less, is particularly preferable in terms of
demonstrating superior (easily stretched) elastic properties.
Furthermore, the tensile stress is measured by carrying out a
tensile test on a sample having a width of 15 mm at a stretching
speed of 200 mm/min.
[0059] A low tensile stress during elongation (meaning that the
resistance during elongation is low enabling the film to be
stretched with a little force) is also an important factor for
perceiving elastic properties. For example, although a composite
film having an elongation percentage of 20% and tensile stress of
3.25 N/15 mm during 10% elongation may be perceived to have
inferior elastic properties, a composite film having the same
elongation percentage but having a tensile stress of 1.85 N/15 mm
during 10% elongation is able to be perceived as being elastic due
to its greater ease of stretching.
[0060] The production process of the elastic composite film in the
present invention is a process of continuously producing the
elastic composite film described above, comprising the steps
of:
[0061] (1) continuously forming the elastomeric resin layer on at
least one side of an expanded, sintered, porous film substantially
consisting of polytetrafluoroethylene (ePTFE);
[0062] (2) continuously elongating the multilayer film obtained in
(1) above at less than the yield point of the sintered ePTFE film
and at an elongation factor of 1.3 times or more in the biaxial
directions, or continuously elongating in the uniaxial direction
without contracting in the direction perpendicular to the direction
of elongation; and
[0063] (3) relaxing the elongated multilayer film obtained in (2)
above.
[0064] In the production process of this elastic composite film,
impregnation can be used as the method for continuously forming a
layer of an elastomeric resin, and preferably a hydrophilic
polyurethane resin, on one side of a multilayer structure of a
sintered ePTFE film. There are no particular limitations on the
method for impregnating the hydrophilic polyurethane resin, and the
polyurethane resin can be coated onto the sintered ePTFE film with,
for example, a roll coater by making the resin into a solution with
a solvent and forming a melt by heating to create a coating liquid.
The viscosity of the coating liquid suitable for impregnation is
preferably 20000 cps or less, and more preferably 10000 cps or less
at the coating temperature. In the case of making the resin into a
solution with a solvent, although dependent on the solvent
composition, if the viscosity is excessively low, the solution
diffuses throughout the entire sintered ePTFE film after coating,
making the entire film hydrophilic. Since this causes problems in
terms of waterproofness and results in an increase in the
impregnated amount of hydrophilic polyurethane resin, the resin
layer ultimately becomes excessively thick, and since a probability
of preventing the obtaining of a high degree of moisture
permeability becomes high, the viscosity is preferably maintained
at 500 cps or more. A B-type viscometer manufactured by Toki Sangyo
Co., Ltd., for example, is used to measure viscosity. Since the
porous structure of the sintered ePTFE film and the impregnability
of the impregnated hydrophilic polyurethane resin vary according to
surface tension, pore size, temperature and pressure, and the like,
conditions are required that enable the hydrophilic polyurethane
resin to form a thin coating on the surface of the sintered ePTFE
film with causing impregnation of the hydrophilic polyurethane
resin and without causing the hydrophilic polyurethane resin to
diffuse throughout the entire sintered ePTFE film. The conditions
for viscosity of a coating liquid containing a hydrophilic
polyurethane resin as previously described are effective for a
sintered ePTFE film having a maximum pore size of about 0.2
.mu.m.
[0065] The production process of the elastic composite film of the
present invention is characterized by elongation treatment while
preventing necking. Namely, the production process is characterized
by elongating in the direction of expansion while maintaining a
constant dimension of the film perpendicular to the direction of
expansion, or while elongating, at or below the yield point of the
sintered ePTFE film.
[0066] An example of an electron micrograph taken at a
magnification of 2000.times. of the surface of sintered ePTFE prior
to this elongation treatment is shown in FIG. 2 for reference
purposes. Nodes and fibrils extending from the nodes can be
observed in FIG. 2. For example, if a sintered ePTFE film is
elongated in the transverse direction without fixing the dimension
in the longitudinal direction, the shapes of the pores are deformed
into long, narrow shapes in the transverse direction, thereby
causing elongation in the transverse direction and necking in the
longitudinal direction. In contrast, elongating without causing
necking as in the present invention increases the total surface
area of the sample by elongation treatment, thus indicating that
fibrils of sintered ePTFE are newly extended from the nodes or that
existing fibrils are further elongated. Although PTFE exhibits
strong plastic deformity and is itself not elastic, it returns to
nearly its original shape (dimensions) in the relaxation step due
to the elasticity of the impregnated elastomeric resin layer. As a
result of elongating the sintered ePTFE followed by returning to
its original dimensions in the relaxation step (as it is a
continuous processing without causing necking), together with the
elasticity of the elastomeric resin layer, it becomes possible for
the first time to achieve an elongation percentage of 30% or more
and elongation recovery rate of 70% or more, while the tensile
stress when elongating by 10% is 2.5 N/15 mm or less. In this
manner, the production process of the present invention and the
elastic composite film obtained thereby are essentially different
from the method described in the aforementioned Japanese Unexamined
Patent Publication No. 59-187845 with respect to the occurrence of
fibril growth and the extension of new fibrils.
[0067] The dimensional recovery rate of the elongated multilayer
film before and after the elongation and relaxation steps in the
production process of the present invention is 80% or more and
preferably 85% or more. If the dimensional recovery rate of the
elongated multilayer film is less than 80%, the elastic properties
of the produced elastic composite film are inadequate. The
dimensional recovery rate is determined by calculating using the
following equation (2) from the dimension of the multilayer film
before elongation treatment (L1), the elongating dimension during
elongation treatment (L2), and the dimension of the elastic
composite film following relaxation of the elongated multilayer
film (L3).
Dimensional recovery rate (%)=(L2-L3)/(L2=L1).times.100 (2)
[0068] In order to perceive desired elastic properties, it is
necessary for the elongation percentage and elongation recovery
rate to be high, and the elongation stress during 10% elongation to
be low. As a result, elongation (ease of stretching) and recovery
(ease of shrinking) can be perceived at low stress. In order to
elongate sintered ePTFE film, a desired elongation factor can be
achieved by elongating while heating to a certain degree. Based on
the balance between elongation and recovery, the elongation
treatment temperature is preferably 100 to 200.degree. C. and
particularly preferably 120 to 180.degree. C.
[0069] If elongation treatment is carried out at an elongation
treatment temperature above 200.degree. C., the elastomeric resin
is set in the elongated state and dimensional recovery following
completion of elongation becomes poor, thus indicating the absence
of elastic properties. In addition, if elongation treatment is
carried out at an elongation treatment temperature below
100.degree. C., since a sintered ePTFE film is used, slipperiness
between fibrils and the extension of new fibrils from the nodes
also become poor, eventually preventing elongation to a desired
elongation factor.
[0070] If a composite film of a sintered ePTFE film and elastomeric
resin having a rupture elongation percentage of 200% of the present
invention is elongated under conditions of, for example, an
elongation factor of 1.4 times and elongation speed of 50%/sec at a
temperature of 150.degree. C., and then allowed to recover (relax)
by releasing tension after elongation, a film having superior
elastic properties is obtained having an elongation percentage of
30%, elongation recovery rate of 90% and elongation stress of 1.85
N/15 mm when elongated by 10%. If the same film is elongated under
conditions of an elongation factor of 1.4 times and elongation
speed of 50%/sec at a temperature of 90.degree. C., the film breaks
during the course of elongation and cannot be elongated. In
addition, a film obtained by elongating the same film at an
elongation factor of 1.4 times and elongation speed of 50%/sec at a
temperature of 210.degree. C. followed by allowing the film to
recover by releasing tension after elongation has inferior elastic
properties, having an elongation percentage of 15%, elongation
recovery rate of 38% and elongation stress of 2.8 N/15 mm when
elongating by 10%.
[0071] Differences in the recovery rate of film dimensions
following the relaxation step are also observed depending on the
elongation speed. If the elongation speed is excessively slow, a
considerable amount of time is required to elongate to a
predetermined elongation factor, and as a result, the thermosetting
time of the film becomes long and elastic properties becomes poor,
similar to elongation treatment at high temperatures. An elongation
speed of 5%/sec or more is preferable, and that of 10%/sec or more
is particularly preferable.
[0072] The ease of stretching of sintered ePTFE films in the
longitudinal and transverse directions can be adjusted according to
the balance of the longitudinal and transverse expansion factors.
Composite films of the sintered ePTFE film and elastomeric resin
also inherit the balance of ease of stretching of the sintered
ePTFE film serving as the base material. For example, a sintered
ePTFE film easily elastic in the transverse direction is obtained
by lowering the expansion factor in the transverse direction
relative to the elongation factor in the longitudinal direction.
Although the present invention does not limit the direction of
stretching ease, since fabrics that stretch in the transverse
direction typically have a larger number of types and are
inexpensive, a sintered ePTFE film that stretches easily in the
transverse direction is used preferably.
[0073] In the production process of the elastic composite film of
the present invention, the elongation step is preferably carried
out under heating conditions of 100 to 200.degree. C. and at an
elongation speed of 5%/sec or more. In the case of elongating in
the transverse direction only while fixing the longitudinal
direction, the elongation factor in the transverse direction is
preferably 1.3 times or more and particularly preferably 1.4 times
or more. In addition, in the case of elongating in the longitudinal
direction only while fixing the transverse direction, the
elongation factor in the longitudinal direction is preferably 1.3
times or more and particularly preferably 1.4 times or more, while
in the case of elongating biaxially, the elongation factor in the
longitudinal direction is preferably 1.3 times or more and
particularly preferably 1.4 times or more, and the elongation
factor in the transverse direction is preferably 1.3 times or more
and particularly preferably 1.4 times or more. If the elongation
factor falls below the aforementioned ranges, there is the risk of
the elastic properties of the resulting elastic composite film
being inadequate. Although the elongation factor is preferably as
high as possible provided the sintered ePTFE film does not break,
it normally has an upper limit of about 2 times in the case of
elongating uniaxially and an upper limit of about 1.7 times in the
case of elongating biaxially.
[0074] In the production process of the elastic composite film of
the present invention, the relaxation step is preferably carried
out under conditions of 100.degree. C. or lower, and particularly
preferably under conditions of room temperature to 80.degree. C. If
the relaxation step is carried out at a temperature above
100.degree. C., since the dimensional recovery rate following the
relaxation step falls below 80%, elastic properties becomes
inadequate. There are no particular limitations on the method of
relaxation, and the elastic composite film may be allowed to
contract naturally by releasing the tension applied thereto.
[0075] The elastic composite fabric of the present invention is a
composite fabric in which an elastic cloth is laminated onto one or
both sides of the elastic composite film described above, wherein,
when the composite fabric is elongated by 10% in the longitudinal
direction and/or transverse direction, the tensile stress of the
composite fabric is 2.5 N/15 mm or less, and/or the elongation
percentage of the composite fabric in the longitudinal direction
and/or transverse direction is 30% or more and the elongation
recovery rate is 70% or more. The tensile stress referred to here
is basically the same as in the case of the aforementioned elastic
composite film with respect to elongation percentage and elongation
recovery rate.
[0076] Although any elastic cloth can be used provided it is able
to fulfill the role of a protective layer of an elastic composite
film and has elastic properties, woven cloths, knits, non-woven
fabrics, nets and the like composed of synthetic fibers or natural
fibers are preferable. Examples of preferably used synthetic fibers
include polyamide, polyester, polyurethane, polyolefin, polyvinyl
chloride, polyvinylidene chloride, polyfluorocarbon and polyacrylic
fibers. In addition, cloths such as elastic polyurethane-based
Spandex fibers, cloths composed of special polyester (PET) fibers,
cloths partially combining these fibers, and cloth referred to as
mechanical stretch cloth in which special "twisting" is applied to
the thread are used preferably as they have excellent elastic
properties. Also, knit and the like are preferably used since they
have structural elastic properties. Examples of natural fibers
include cotton, hemp, wool and silk.
[0077] In the case of laminating an elastic composite film and an
elastic cloth, a method to form a two-layer structure in which the
cloth is laminated onto one side of the elastic composite film, or
a method to form a three-layer structure in which the cloth is
laminated onto both sides of the elastic composite film can be
used.
[0078] The process for continuously producing an elastic composite
fabric in the present invention comprises the steps of:
[0079] (1) continuously forming the elastomeric resin layer on at
least one side of an expanded, sintered, porous (sintered ePTFE)
film substantially consisting of polytetrafluoroethylene;
[0080] (2) continuously laminating an elastic cloth onto one or
both sides of the multilayer film obtained in (1) above, and
continuously elongating the laminated fabric obtained in the
lamination step at less than the yield point of the sintered ePTFE
film and at an elongation factor of 1.3 times or more in the
biaxial directions, or continuously elongating it in the uniaxial
direction without contracting in the direction perpendicular to the
direction of elongation; or
[0081] (2') continuously elongating the multilayer film obtained in
(1) above at less than the yield point of the sintered ePTFE film
and at an elongation factor of 1.3 times or more in the biaxial
directions, or continuously elongating it in the uniaxial direction
without contracting in the direction perpendicular to the direction
of elongation, and continuously laminating the elastic cloth onto
one or both sides of the elongated multilayer film obtained the
elongation step; and,
[0082] (3) relaxing the elongated laminated fabric obtained in (2)
or (2') above.
[0083] Here, the method for forming the elastomeric resin layer on
the surface of the sintered ePTFE film is basically the same as in
the aforementioned production process of an elastic composite film.
In addition, the step for elongating the laminated fabric and the
step for relaxing the elongated laminated fabric are basically the
same as the previously described methods.
[0084] Elongation treatment may be carried out after laminating the
elastic cloth onto the multilayer film in which the elastomeric
resin layer has been formed on the sintered ePTFE film, or the
elastic cloth may also be laminated after carrying out elongation
treatment on the multilayer film.
[0085] Lamination of the elastic composite film and elastic cloth
can be carried out using a known method. For example, a method in
which an adhesive is applied to the elastic composite film with a
roller containing a gravure pattern followed by aligning the
elastic cloth thereon and press-bonding the elastic cloth with a
roller, a method in which an adhesive is sprayed onto the elastic
composite film followed by aligning the elastic cloth thereon and
press-bonding with a roller, or a method in which the elastic
composite film and elastic cloth are superimposed followed by heat
fusing with a heated roller, can be used.
[0086] Lamination of the elastic cloth and elastic composite film
is preferably obtained by adhesion. Various types of adhesives
known in the prior art can be used as the adhesive for this purpose
provided it does not easily decrease in adhesive strength under
ordinary conditions of use. Non-water-soluble adhesives are used in
general. Examples of such non-water-soluble adhesives include
thermoplastic resins as well as thermosetting resins cured by heat,
light and the like. Specific examples of non-water-soluble
adhesives that can be suitably used include various types of resins
such as polyester, polyamide, polyurethane, silicone, polyacrylic,
polyvinyl chloride, polybutadiene, rubber and polyolefin-based
resins. Polyurethane-based resins in the form of curing
reaction-type hot melt adhesives are used particularly preferably.
Although the curing reaction-type hot melt adhesives in this case
refers to those that are a solid at ambient temperatures and have a
low-viscosity liquid when melted by heating, by coating in a liquid
state and then maintaining in this state, or by further heating, a
curing reaction occurs resulting in an adhesive in the form of a
high-viscosity liquid or solid. In this case, the viscosity of the
melt when melted by heating, namely prior to coating onto a liner
fabric, is 500 to 30000 cps and preferably 500 to 3000 cps. On the
other hand, the viscosity of the melt when the melt is obtained in
the form of a high-viscosity liquid, namely when the film and liner
fabric are laminated with the melt, is 500 to 20000 cps and
preferably 10000 cps or higher. Furthermore, the curing reaction of
the melt proceeds in the presence of a curing catalyst, curing
agent and moisture.
[0087] A preferable example of the aforementioned curing
reaction-type adhesive is a urethane polymer that undergoes a
curing reaction due to the presence of humidity (moisture). This
urethane polymer can be obtained by an addition reaction of (I) a
polyol component such as a polyester polyol or polyether polyol,
and (II) a polyisocyanate component such as an aliphatic or
aromatic diisocyanate or triisocyanate such as tolylene
diisocyanate (TDI), methylene bisphenyl diisocyanate (MDI), xylene
diisocyanate or isophorone diisocyanate. In this case, this
urethane polymer has an isocyanate group on the terminal thereof
and undergoes a curing reaction in the presence of humidity. In
this urethane polymer, the melting temperature is slightly higher
than room temperature, 50.degree. C. or higher and preferably 80 to
150.degree. C. This type of urethane polymer can be acquired
commercially under, for example, the trade name "BondMaster" from
Nippon NSC Ltd. This polymer becomes a melt having a viscosity
enabling coating processing onto a base material as a result of
being heated to 70 to 150.degree. C., and after laminating an
elastic cloth and elastic composite film using this melt, the
polymer changes to a semi-solid state as a result of cooling to
about room temperature, thereby preventing excessive penetration
and diffusion of the adhesive into the fabric while also being
cured by moisture in the air, thereby allowing the obtaining of
soft yet powerful adhesion.
[0088] The surface area of adhesion or fusion-bonding in the case
of carrying out the lamination described above is 3 to 90% and
preferably 5 to 80%. If the surface area is less than 3%, the
adhesive or fusion-bonding strength between the elastic composite
film and elastic cloth is unable to be adequately obtained, while
if the surface area exceeds 90%, the texture of the resulting
elastic composite fabric becomes hard and water vapor permeability
is also inadequate.
[0089] A textile product of the present invention comprises the
elastic composite fabric described above. Textile products refer to
products containing cloth as a constituent feature thereof, and
examples include clothing products such as garments, caps, gloves
and socks, bedding products such as futons, sheets and sleeping
bags, film structures such as tents, and bags such as portfolios.
For example, in the case of rainwear provided with water vapor
permeability that uses a bi-layer structured, elastic composite
fabric of the present invention, the rainwear is used with the
elastic cloth side on the outside and the elastomeric resin layer
side on the inside next to the body.
[0090] If the sintered ePTFE film side is used on the inside next
to the body, water vapor generated from the body passes through the
pores of the sintered ePTFE film, penetrates to the inside of the
elastomeric resin layer by adhering to the surface of the
elastomeric resin penetrating inside the pores where it diffuses,
and then evaporates from the surface of the elastomeric resin
layer. Consequently, the substantial effective film surface area of
the elastomeric resin at the surface to which water vapor adheres
and penetrates is limited to the pores thereof. Consequently, water
vapor permeability decreases as compared with using the elastomeric
resin on the inside next to the body. In addition, as a result of
using the elastomeric resin side on the inside next to the body,
perspiration, sebum and other contaminants generated from the body
are cut off at the surface of the elastomeric resin layer, thereby
demonstrating the effect of being able to prevent contamination of
the sintered ePTFE film by contaminants.
[0091] Since the cloth side is normally used being exposed on the
outer surface of rainwear, when the cloth exposed on the outer
surface absorbs water, a water film is formed on the surface of the
rainwear, which not only inhibits water vapor permeability of the
elastic composite fabric, but also increases the sheet weight,
decreasing comfort. Thus, the outer surface of the rainwear is
preferably subjected to water repellency treatment with
fluorine-based water repellent agent or silicone-based water
repellent agent and the like.
[0092] Although the following provides a more detailed explanation
of the present invention through working examples thereof, the
present invention is not limited to these working examples.
EXAMPLE 1
[0093] Ethylene glycol was added to a hydrophilic polyurethane
resin (Dow Chemical Co., trade name: Hipore 2000) at a ratio in
which the equivalent weight ratio of NCO/OH is 1, followed by the
addition of toluene so that the concentration of the polyurethane
pre-polymer was 90% by weight, and mixing and stirring well to
prepare a coating liquid. This coating liquid was coated onto a
sintered ePTFE film manufactured by Japan Gore-Tex Inc. (thickness:
50 .mu.m, maximum pore diameter: 0.3 .mu.m, porosity: 80%, rupture
elongation percentage in transverse direction as determined in a
tensile test: 260%), and cured by heating to obtain a multilayer
film in which the thickness of the polyurethane resin layer was 25
.mu.m (thickness of impregnated portion: 15 .mu.m, thickness of
surface portion: 10 .mu.m). Next, this multilayer film was
subjected to continuous elongation treatment in the transverse
direction under the conditions shown in Table 1 with an apparatus
having a tenter that spreads apart in a heater oven, the film was
removed from the tenter immediately after elongation, and then
continuously wound while allowing to contract naturally at room
temperature. Furthermore, the film was moved at a constant speed so
as not to substantially elongate the film in the longitudinal
direction.
[0094] More specifically, the aforementioned multilayer film was
subjected to elongation treatment according to the previously
described method at an elongation temperature of 150.degree. C.,
elongation factor in the transverse direction of 1.5 times, and
elongation speed of 6%/sec to produce an elastic composite film.
The elongation percentage and elongation recovery rate of the
resulting elastic composite film were measured according to the
methods previously described.
[0095] As a result, as shown in Table 1, a film having superior
elastic properties was obtained having an elongation percentage of
35% in the transverse direction, an elongation recovery rate of
85%, and stress of 1.5 N/15 mm during 10% elongation. Furthermore,
the elongation percentage of the composite film in the transverse
direction prior to elongation treatment was 10%, the elongation
recovery rate was 65% and the stress during 10% elongation was 3.0
N/15 mm.
COMPARATIVE EXAMPLE 1
Effect of Elongation Speed
[0096] A composite film was produced under the same conditions as
Example 1 with the exception of changing the elongation speed to
1%/sec. The resulting composite film had poor elastic properties,
with an elongation percentage in the transverse direction of 19%,
elongation recovery rate of 80% and stress of 2.6 N/15 mm during
10% elongation. The evaluation results are also shown in Table
1.
COMPARATIVE EXAMPLE 2
Effect of Elongation Temperature
[0097] A composite film was produced under the same conditions as
Example 1 with the exception of using an elongation temperature of
220.degree. C. The elongation percentage of the resulting composite
film in the transverse direction was 5%, the elongation recovery
rate was 50%, and the stress during 10% elongation was 2.7 N/15 mm.
If the elongation temperature is excessively high even for the same
elongation speed, the effect of thermosetting increases, and this
resulted in a film having inadequate elastic properties. The
evaluation results are also shown in Table 1.
COMPARATIVE EXAMPLE 3
Effect of Elongation Temperature
[0098] When a multilayer film was subjected to elongation treatment
under the same conditions as Example 1 with the exception of using
an elongation temperature of 90.degree. C., the multilayer film
ruptured and elongation treatment was unable to be carried out.
EXAMPLE 2
[0099] An elastic composite film was produced under the same
conditions as Example 1 with the exception of using an elongation
temperature of 170.degree. C., elongation factor of 1.6 times in
the transverse direction, and elongation speed of 13%/sec. The
evaluation results are shown in Table 1. A film having superior
elastic properties was obtained having an elongation percentage of
42% in the transverse direction, an elongation recovery rate of 85%
and stress of 1.4 N/15 mm during 10% elongation, by increasing the
elongation factor and setting a faster elongation speed.
TABLE-US-00001 TABLE 1 Elongation Elongation Elon- Elongation
percentage recovery Stress gation factor in Elon- in rate in during
temper- transverse gation transverse transverse 10% ature direction
speed direction direction elongation No. (.degree. C.) (times)
(%/sec) (%) (%) (N/15 mm) Ex. 1 150 1.5 6 35 85 1.5 Comp. 150 1.5 1
19 80 2.6 ex. 1 Comp. 220 1.5 6 5 50 2.7 ex. 2 Ex. 2 170 1.6 13 42
85 1.4
EXAMPLE 3
[0100] An adhesive manufactured by Nippon NSC Ltd. ("BondMaster")
was transferred in the form of dots on the sintered ePTFE film side
of the elastic composite film of Example 2 using a gravure roller
having a transfer surface area of 40%, followed by laminating a
knit cloth (Nylon/Spandex blend: 75/25, gauge: 28G, weight: 58
g/m.sup.2, transverse direction elongation percentage: 150%,
elongation recovery rate: 95%) onto the transfered side, and
applying pressure to obtain a bi-layer structured, elastic
composite fabric. The resulting elastic composite fabric had
elastic characteristics of an elongation percentage of 35% in the
transverse direction and elongation recovery rate of 93%. In
addition, the adhesive durability between the film and liner fabric
of this laminate was evaluated based on the presence or absence of
the peel-off by visual observation of a sample following 100 hours
of continuous agitation laundering using tap water containing no
detergent at a bath ratio of 1/60, bath temperature of 45.degree.
C. or lower and in the heavy-duty mode using a type B home-use
washing machine as described in ISO 6330 (Kenmore Model 110.20912,
Sears Roebuck & Co.). As a result, there was no peel-off.
COMPARATIVE EXAMPLE 4
[0101] An elastic composite film was produced under the same
conditions as Example 1 with the exception of using an unsintered
ePTFE film. An elastic composite fabric was produced under the same
conditions as Example 3 using the resulting elastic composite film.
As a result of the aforementioned continuous laundering test on
this elastic composite fabric, a portion of the elastic composite
fabric peeled off. Observation of the separated portion revealed
that the peel-off was caused by aggregation and destruction of the
ePTFE layer.
EXAMPLE 4
[0102] A bi-layer structured, laminated fabric, obtained by
laminating a knit cloth (Nylon/Spandex blend: 75/25, gauge: 28G,
weight: 58 g/m.sup.2, transverse direction elongation percentage:
150%, elongation recovery rate: 95%) onto the sintered ePTFE film
side of the multilayer film (not subjected to elongation treatment)
of Example 1 under the same conditions as Example 3, was subjected
to elongation treatment in the same manner as Example 1 with the
exception of using an elongation temperature of 110.degree. C.,
transverse direction elongation factor of 1.8 times and elongation
speed of 20%/sec. As a result of evaluating the resulting elastic
composite fabric, the fabric had superior elastic properties,
demonstrating an elongation percentage of 45% in the transverse
direction, elongation recovery rate of 92% and stress of 1.7 N/15
mm during 10% elongation.
EXAMPLE 5
[0103] A bi-layer structured, laminated fabric was produced by
laminating a knit cloth (Nylon/Spandex blend: 75/25, gauge: 28G,
weight: 58 g/m.sup.2, transverse direction elongation percentage:
150%, elongation recovery rate: 95%) onto the sintered ePTFE film
side of the multilayer film (not subjected to elongation treatment)
of Example 1 under the same conditions as Example 3. Moreover, the
same knit cloth was laminated onto the other side of the multilayer
film in the same manner to obtain a tri-layer structured, laminated
fabric. This laminated fabric was subjected to elongation treatment
in the same manner as Example 4. As a result of evaluating the
resulting elastic composite fabric, the fabric had superior elastic
properties, demonstrating an elongation percentage of 35% in the
transverse direction, elongation recovery rate of 95% and stress of
2.0 N/15 mm during 10% elongation.
EXAMPLE 6
[0104] A bi-layer structured, laminated fabric was produced by
laminating a woven cloth (2/2 twill structure composed of Nylon
twisted yarn, density: 170.times.160 threads/inch, weight: 82
g/m.sup.2, transverse direction elongation percentage: 35%,
elongation recovery rate: 90%) onto the sintered ePTFE film of the
laminated film (not subjected to elongation treatment) of Example 1
under the same conditions as Example 3. This laminated fabric was
subjected to elongation treatment in the same manner as Example 1
with the exception of using an elongation temperature of
150.degree. C., transverse direction elongation factor of 1.4 times
and elongation speed of 20%/sec. A fabric having superior elastic
properties was obtained having an elongation percentage in the
transverse direction of 25%, an elongation recovery rate of 88%,
and stress of 1.96 N/15 mm during 10% elongation.
EXAMPLE 7
[0105] The multilayer film of Example 1 was elongated by 1.5 times
at 170.degree. C. The elongation speeds at that time were 5%/sec,
1%/sec, 0.5%/sec or 0.3%/sec. The other conditions were the same as
in Example 1. The results of evaluating the resulting composite
films are shown in FIG. 3. Films were obtained that demonstrated a
higher elongation percentage at the faster the elongation
speed.
* * * * *