U.S. patent application number 10/644237 was filed with the patent office on 2004-02-26 for organic fibers and textile products.
Invention is credited to Iwato, Satoko, Kaku, Mureo, Kosuge, Kazuhiko, Nakamura, Hideo.
Application Number | 20040034941 10/644237 |
Document ID | / |
Family ID | 31884540 |
Filed Date | 2004-02-26 |
United States Patent
Application |
20040034941 |
Kind Code |
A1 |
Iwato, Satoko ; et
al. |
February 26, 2004 |
Organic fibers and textile products
Abstract
A high-strength, heat-resistant organic fiber and textile
product each comprising or having coated thereon an aqueous
emulsion is provided. The emulsion comprises or is produced from a
fluorocarbon silane or an emulsion, said emulsion comprises or is
produced from (1) a fluorocarbon silane or its hydrolyzate, (2)
water, and (3) optionally a surfactant, an alkoxysilane compound,
catalyst, or combinations of two or more thereof; said fluorocarbon
silane having the formula R.sub.f--(CH.sub.2).sub.p--Si-
{--(O--CH.sub.2CH.sub.2).sub.n--OR.sup.1}.sub.3; R.sub.f is a
C.sub.3-18 perfluoroalkyl group or combinations of two or more
thereof; each R.sup.1 is independently one or more C.sub.1-3 alkyl
groups; p is 2 to 4; and n is 2 to 10. Also disclosed is a process
for producing the emulsion, the fiber, and the textile product.
Inventors: |
Iwato, Satoko; (Tokyo,
JP) ; Kaku, Mureo; (Utsunomiya-Shi, JP) ;
Nakamura, Hideo; (Tokyo, JP) ; Kosuge, Kazuhiko;
(Tokyo, JP) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
31884540 |
Appl. No.: |
10/644237 |
Filed: |
August 20, 2003 |
Current U.S.
Class: |
8/115.51 |
Current CPC
Class: |
D03D 15/283 20210101;
D10B 2501/041 20130101; D10B 2331/042 20130101; D06M 15/643
20130101; D10B 2331/021 20130101; D03D 15/573 20210101; D06M 15/657
20130101; D10B 2401/063 20130101; D06M 13/513 20130101; D06M
2200/11 20130101; D03D 15/513 20210101; D06M 2200/12 20130101; D06M
15/647 20130101 |
Class at
Publication: |
8/115.51 |
International
Class: |
D06M 010/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 21, 2002 |
JP |
2002-241122 |
Claims
What is claimed is:
1. A composition comprising a fiber which comprises or has coated
thereon a thin film wherein said thin film comprises or is produced
from a fluorocarbon silane or an emulsion, said emulsion comprises
or is produced from (1) a fluorocarbon silane or its hydrolyzate,
(2) water, and (3) optionally a surfactant, an alkoxysilane
compound, a catalyst, or combinations of two or more thereof; said
fluorocarbon silane has the formula
R.sub.f--(CH.sub.2).sub.p--Si{--(O--CH.sub.2CH.sub.2).sub.n--OR.s-
up.1}.sub.3; R.sub.f is a C.sub.3-18 perfluoroalkyl group or
combinations of two or more thereof; each R.sup.1 is independently
one or more C.sub.1-3 alkyl groups; p is 2 to 4; and n is 2 to
10.
2. The composition of claim 1 wherein said thin film further
comprises, or is further produced from, a copolycondensate of said
fluorocarbon silane and an alkoxysilane.
3. The composition of claim 1 wherein said thin film has a
thickness of less than 1,000 nm.
4. The composition of claim 2 wherein said thin film has a
thickness of less than 1,000 nm.
5. The composition of claim 1 wherein said fiber is an aromatic
polyamide fiber, an aromatic polyester fiber, a heterocyclic
aromatic fiber, or combinations of two or more thereof.
6. The composition of claim 2 wherein said fiber is an aromatic
polyamide fiber, an aromatic polyester fiber, a heterocyclic
aromatic fiber, or combinations of two or more thereof.
7. The composition of claim 3 wherein said fiber is an aromatic
polyamide fiber, an aromatic polyester fiber, a heterocyclic
aromatic fiber, or combinations of two or more thereof.
8. The composition of claim 4 wherein said fiber is an aromatic
polyamide fiber, an aromatic polyester fiber, a heterocyclic
aromatic fiber, or combinations of two or more thereof.
9. The composition of claim 5 wherein said fiber is a p-phenylene
terephthalamide fiber.
10. The composition of claim 6 wherein said fiber is a p-phenylene
terephthalamide fiber.
11. The composition of claim 7 wherein said fiber is a p-phenylene
terephthalamide fiber.
12. The composition of claim 8 wherein said fiber is a p-phenylene
terephthalamide fiber.
13. A textile product comprising or produced from a fiber having
coated thereon an emulsion, which comprises or is produced from (1)
a fluorocarbon silane or its hydrolyzate, (2) water, and (3)
optionally a surfactant, an alkoxysilane compound, a catalyst, or
combinations of two or more thereof.
14. The product of claim 13 wherein said product is a woven
product, a knit product, a nonwoven fabric, or combinations of two
or more thereof.
15. The product of claim 14 wherein said product is a woven fabric
for protective clothing.
16. The product of claim 14 wherein said product is a firefighting
apparel.
17. The product of claim 14 wherein said product is a glove.
18. A process comprising combining a fluorocarbon silane or its
hydrolyzate, water, and optionally a surfactant, an alkoxysilane
compound, a catalyst, or combinations of two or more thereof to
produce a mixture and optionally heating said mixture to produce an
emulsion wherein said fluorocarbon silane having the formula
R.sub.f--(CH.sub.2).sub.p--Si{--(O--CH.sub.2CH.sub.2).sub.n--OR.sup.1}.su-
b.3; R.sub.f is a C.sub.3-18 perfluoroalkyl group or combinations
of two or more thereof; each R.sup.1 is independently one or more
C.sub.1-3 alkyl groups; p is 2 to 4; and n is 2 to 10.
19. The process of claim 18 further comprising producing a thin
film of said emulsion onto a fiber wherein said thin film has a
thickness of less than 1000 nm.
20. The process of claim 19 wherein said thin film further
comprises, or is further produced from, a copolycondensate of said
fluorocarbon silane and an alkoxysilane.
21. The process of claim 19 wherein said fiber is an aromatic
polyamide fiber, an aromatic polyester fiber, a heterocyclic
aromatic fiber, or combinations of two or more thereof.
22. The process of claim 20 wherein said fiber is an aromatic
polyamide fiber, an aromatic polyester fiber, a heterocyclic
aromatic fiber, or combinations of two or more thereof.
23. The process of claim 18 further comprising producing a thin
film of said emulsion onto a textile product wherein said thin film
has a thickness of less than 1000 nm.
24. The process of claim 23 wherein said thin film further
comprises, or is produced from, a copolycondensate of said
fluorocarbon silane and an alkoxysilane.
25. The process of claim 24 further comprising producing a product
which is a woven product, a knit product, a nonwoven fabric, or
combinations of two or more thereof.
26. The process of claim 25 wherein said product is a woven fabric
for protective clothing.
27. The process of claim 25 wherein said product is a firefighting
apparel.
28. The process of claim 25 wherein said product is a glove.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an organic fiber having
water repellence and oil repellence, to a textile product
comprising the fiber, and to a method for producing the fiber and
textile product.
BACKGROUND OF THE INVENTION
[0002] It is regarded as desirable for textile products to prevent
not only hydrophilic stains, but also lipophilic stains.
Hydrophilic stains can be prevented by means of water repellence,
and lipophilic stains can be prevented by means of oil repellence.
Hence, techniques for conferring fibers or textile products with
water and oil repellency have been investigated and, for some
applications, have already been put to practical use. A number of
methods are used for conferring fibers or textile products with
stainproofing capabilities arising from such water and oil
repelling properties. For example, finishes or coating agents may
be used. That is, the fiber or textile product is immersed in an
emulsion or solution of a silicone polymer, fluorocarbon polymer,
polyurethane polymer, vinyl polymer or a copolymer of any of the
above, or a spray containing ingredients such as the above polymers
is applied to the fiber or the textile product, following which
drying is carried out so as to form a film on the surface of the
fibers. Another method in current use involves polymerizing
monomers or oligomers as precursors to these polymers on the fiber
surface so as to form a film.
[0003] However, while covering the entire surface of the textile
product with the above-described film by one of these methods does
indeed impart the fibers with stainproofing properties, such an
approach has resulted in a considerable loss in the inherent hand
of the fibers. A coating of the above type makes it particularly
difficult to satisfy requirements for breathability and moisture
permeability. While it is also possible to individually coat each
fiber or fiber bundle making up the textile product, when a polymer
dispersion is used, a film of smaller thickness than the size of
the particles in the dispersion cannot be formed. In most cases,
the film has a thickness of at least several tens of microns, and
also lacks adequate strength.
[0004] As a result, when the fibers are individually coated with
such a coating agent, the coat has a certain thickness, which
compromises the hand of the fibers and the textile product. There
also exists a thin film-forming method which uses a liquid-type
coating, and subjects a polymer precursor on the fiber surface to
polymerization and solidification. Unfortunately, it is difficult
to obtain a thin film of sufficient durability in this way.
[0005] Moreover, at the high temperatures which high-strength,
high-resistant organic fibers are expected to withstand, the
polymers used for coating in this way melt or decompose, and
sometimes even ignite. Hence, they lack heat resistance and flame
resistance, and are thus ill-suited for applications requiring heat
resistance and flame resistance, such as firefighting apparel.
Accordingly, there is a desire for fibers, and textile products
made thereof, which are endowed with excellent heat resistance and
durability with no loss of hand, and which have an excellent
stainproofing performance.
[0006] Such textile products can be woven products, knit products
or nonwoven fabric. Preferred applications include firefighting
apparel, gloves and woven fabric for protective clothing.
SUMMARY OF THE INVENTION
[0007] A composition is provided which comprises an organic fiber
comprising a thin film which comprises a fluorocarbon silane.
[0008] Also provided is a textile product comprising an organic
fiber comprising a thin film which comprises a fluorocarbon
silane.
[0009] Further provided is a process that can be used for
manufacturing a high-strength, heat-resistant fiber or textile
product which comprises contacting a fiber or textile product with
an aqueous emulsion comprising, or produced by combining, (1) a
fluorocarbon silane or its hydrolyzate and (2) optionally a
surfactant, an alkoxysilane compound, catalyst, or combinations or
two or more thereof to produce a fiber or textile-containing
mixture and optionally heating the mixture.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Any organic fibers of high-strength, heat-resistance can be
used. Preferably the fiber can be coated with a thin film
comprising a fluorocarbon silane or a thin film comprising a
copolycondensate of a fluorocarbon silane with an alkoxysilane.
Preferably, a suitable fiber has a strength of about 10 g/D to
about 50 g/D, preferably 15 g/D to 50 g/D, and a pyrolysis
temperature of at least about 300.degree. C., and preferably at
least 350.degree. C. Examples of preferred high-strength,
heat-resistant organic fibers include wholly aromatic polyamide
fibers, wholly aromatic polyester fibers and heterocyclic aromatic
fibers, and mixture of two or more fibers.
[0011] Suitable wholly aromatic polyamide fibers may be any known
aromatic polyamide fibers. Wholly aromatic polyamide fibers are
also known as aramid fibers, which are broadly categorized as
para-aramid fibers or meta-aramid fibers. Such aramid fibers may be
produced and used by any methods known to one skilled in the art.
Para-aramid fibers may be any known para-aramid fiber. Illustrative
examples of such para-aramid fibers include, but are not limited
to, commercial products such as poly(p-phenylene terephthalamide)
fibers (produced by E. I. Du Pont de Nemours and Company and Du
Pont-Toray Co., Ltd. with the trademark KEVLAR.RTM.), p-phenylene
terephthalamide/p-phenylene 3,4'-diphenylene ether terephthalamide
copolymer fibers (produced by Teijin Ltd. under the trade name
TECHNORA), or combinations of two or more thereof. Meta-aramid
fibers may be any known meta-aramid fibers. Illustrative examples
of such meta-aramid fibers include, but are not limited to,
commercial products such as poly(m-phenylene terephthalamide)
fibers (produced by E. I. Du Pont de Nemours and Company under the
trademark NOMEX.RTM.).
[0012] Suitable wholly aromatic polyester fibers may be any known
aromatic polyester fibers. Illustrative examples of such wholly
aromatic polyester fibers include, but are not limited to,
self-condensed polymers of p-hydroxybenzoic acid, polyesters
comprising repeat units derived from terephthalic acid and a
glycol, polyesters comprising repeat units derived from
terephthalic acid and hydroquinone, polyester fibers comprising
repeat units derived from p-hydroxybenzoic acid and
6-hydroxy-2-naphthoic acid, or combinations of two or more thereof.
Such wholly aromatic polyester fibers may be produced and used by
any methods known to one skilled in the art. For example, suitable
wholly aromatic polyester fibers include such commercial products
made by Kuraray Co., Ltd. under the trade name designation
VECTRAN.
[0013] Heterocyclic aromatic fibers used in the invention may be
any fibers known to one skilled in the art. Illustrative examples
of such heterocyclic aromatic fibers include, but are not limited
to, poly(p-phenylene benzobisthiazole) fibers, poly(p-phenylene
benzobisoxazole) fibers (PBO), polybenzimidazole fibers, or
combinations of two or more thereof. Such heterocyclic aromatic
fibers may be produced and used by any methods known to one skilled
in the art. For example, heterocyclic aromatic fibers include
commercial PBO fibers such as those made by Toyobo Co., Ltd. under
the trade name designation ZYLON.
[0014] The preferred high-strength, heat-resistant organic fibers
are aramid fibers made of a para-type homopolymer which are known
to one skilled in the art as KEVLAR.RTM. or TWARON (made by Teijin
Ltd.) for their stability to dimensional change at elevated
temperatures such as, for example, peeling of the thin film, for
their heat resistance, and for their relatively low cost and good
versatility. Preferably, the thin film has a thickness of about
1,000 nm or lower and a strength of 10 to 50 g/D. Also preferred is
one or more selected from the group consisting of wholly aromatic
polyamide fibers, wholly aromatic polyester fibers, heterocyclic
aromatic fibers, and combinations of two or more thereof.
p-Phenylene terephthalamide fibers are especially preferred.
[0015] The textile products comprise fibers comprising, or coated
thereon with, a thin film, which comprises or is produced from a
fluorocarbon silane or its hydrolyzate, or a copolycondensate of a
fluorocarbon silane with an alkoxysilane. Illustrative examples of
suitable textile products include, but are not limited to, products
obtained by the processing of fibers, such as yarn, batting, woven
goods, knit goods, a broad range of nonwoven fabrics, including
felt and paper, as well as roving and cord, and combinations of two
or more thereof. The textile products can also include finished
goods which are products obtained by these products alone, in
combinations thereof, or in combination with other materials, such
as resins or metals. The textile products are preferably woven
goods, knit goods or nonwoven fabrics. Fire-fighting apparel,
gloves and woven fabric for protective clothing are especially
preferred.
[0016] The high-strength, heat-resistant organic fibers or textile
products comprising, or coated thereon with (that is, having a thin
film formed on the surface), a thin film of a copolycondensate of a
fluorocarbon silane with an alkoxysilane can be produced by
treating the organic fibers or the textile products with an aqueous
emulsion comprising (1) a fluorocarbon silane hydrolyzate or
hydrolyzate thereof, (2) water and optionally (3) a surfactant, an
alkoxysilane compound, and a catalyst to produce a fiber- or
textile-containing mixture followed by optionally heating the
mixture.
[0017] The aqueous emulsion can be produced using a fluorocarbon
silane and, optionally, a surfactant, a catalyst and an
alkoxysilane. It is preferably carried out by dispersing a
fluorocarbon silane and an amount of surfactant corresponding to
0.01 to 10, preferably 0.1 to 1 part by weight per part by weight
of the overall fluorocarbon silane in water such as to make the
fluorocarbon silane content, based on the total weight of the
emulsion, from about 0.1 to about 20 wt %, and preferably from 1 to
10 wt %. An acid or alkali catalyst can be added in a catalytic
amount (i.e., about 1 to about 1000 ppm final concentration of the
emulsion) to the resulting aqueous dispersion, following which an
alkoxysilane can be added in an amount corresponding to a mole
fraction of 0.1 to 10, and preferably 0.4 to 0.6, based on the
fluorocarbon silane to produce a mixture. The mixture of the
ingredients can be gently mixed. To obtain a uniform and strong
thin film having a thickness of 1,000 nm or less, preferably 500 or
less, more preferably 100 nm or less, and even more preferably 50
nm or less, it is preferable to suppress as much as possible the
self-condensation reaction by the fluorocarbon silane and/or the
alkoxysilane. For this purpose, it is preferable to thoroughly stir
the mixture, and to avoid overly rapid addition of the fluorocarbon
silane and the alkoxysilane.
[0018] The fluorocarbon silane is preferably at least one type of
hydrolyzable fluorocarbon silane having the formula
R.sub.f--(CH.sub.2).sub.p--Si{--(O--CH.sub.2CH.sub.2).sub.n--OR.sup.1}.su-
b.3. In the formula, R.sub.f is a C.sub.3-18 perfluoroalkyl group
or a mixture of such groups; the plurality of R.sup.1 groups can be
the same or different and are independently one or more C.sub.1-3
alkyl groups; p is 2 to 4; and n is 2 to 10. R.sub.f is preferably
a mixture of perfluoroalkyl groups having an average of 8 to 12
carbon atoms; R.sup.1 represents methyl groups; p is 2; and n is
from 2 to 4, preferably 2 to 3. More specifically, when n is 2, a
perfluoroalkylethyltris(2-(2-methoxy- ethoxy)ethoxy)silane is
especially preferred. When the letter n is 3, a
(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)silane is especially
preferred. This type of fluorocarbon silane can be produced by any
methods known to one skilled in the art. Two or more fluorocarbon
silanes can also be used.
[0019] Exemplary alkoxysilanes include organosilicon compounds
having at least two alkoxy groups on the molecule, and partial
condensation products thereof. Illustrative examples include (1)
silicate of the formula Si(R).sub.4 wherein R is one or more group
selected from among OCH.sub.3, OCH.sub.2CH.sub.3 and
(OCH.sub.2CH.sub.2).sub.mOCH.sub.3 (m being from 1 to 10); and (2)
organoalkoxysilanes of the formula
R.sup.2.sub.nSi(OR.sup.3).sub.4-q wherein R.sup.2 is one or more
C.sub.1-10 alkyls; the plurality of R.sup.3 groups are the same or
different and independently one or more C.sub.1-3 alkyls; and q is
from 1 to 3). The alkyl group R.sup.2 may be substituted with
suitable substituents, such as amino groups, epoxy groups, vinyl
groups, methacryloxy groups, thiol groups, urea groups or mercapto
groups. Specific examples of suitable alkoxysilanes include, but
are not limited to, dimethyldimethoxysilane,
methyltrimethoxysilane, 3-aminopropyltriethoxysilane,
N-(2-aminoethyl)-3-aminopropylmethyldiethox- ysilane and
3-glycidoxypropyltrimethoxysilane, and well as mixtures and partial
condensation products of any of the above.
[0020] Any acid or an alkalilinic substance may be used as the
catalyst. Specific examples of suitable acids include, but are not
limited to, phosphoric acid, boric acid, hydrochloric acid,
sulfuric acid, nitric acid, acetic acid, formic acid, and mixtures
of two or more thereof. Specific examples of suitable alkalis
include, but are not limited to, ammonia, pyridine, sodium
hydroxide, potassium hydroxide, and mixtures of two more thereof.
The use of hydrochloric acid or phosphoric acid as the catalyst in
carrying out the invention is especially preferred.
[0021] Any surfactants that can stabilize the above-described
emulsion may be used. The surfactant generally is a surfactant
having an HLB value sufficiently high to inhibit self-condensation
of the fluorocarbon silane hydrolysis product. The term "HLB"
refers to the HLB system published by ICI America's, Inc.,
Wilmington, Del.; Adamson, A. W., "Physical Chemistry of Surfaces",
4.sup.th edition, John Wily & Sons, New York, 1982). The
surfactant can be anionic, cationic, nonionic, amphoteric, or
combinations thereof. The preferred surfactants are those with HLB
values greater than 5, preferably greater than 12, and more
preferably greater than 16. Examples of nonionic surfactants
include, but are not limited to,
R.sub.f.sup.1--CH.sub.2CH.sub.2--O--(CH.sub.2CH.sub.2O).sub.11--H,
C.sub.9H.sub.19--C.sub.6H.sub.4--O--(CH.sub.2CH.sub.2O).sub.50--H,
other nonionic surfactants, and combinations thereof. Examples of
cationic surfactants include, but are not limited to
R.sub.f.sup.1--CH.sub.2CH.sub-
.2SCH.sub.2CH(OH)CH.sub.2N(CH.sub.3).sub.3.sup.+Cl.sup.-, other
cationic surfactants, and combinations thereof. Examples of anionic
surfactants include, but are not limited to,
C.sub.12H.sub.25(OCH.sub.2CH.sub.2).sub.-
4OSO.sub.3.sup.-NH.sub.4.sup.+,
C.sub.12H.sub.27--C.sub.6H.sub.4--SO.sub.3- .sup.-Na.sup.+, other
anionic surfactants, and combinations or two or more thereof. In
each of the formulae, R.sub.f.sup.1 is a perfluoroalkyl group
generally having about 3-18 carbon atoms. The preferred surfactants
are nonionic surfactants having polyethylene glycol in the
molecular chain. The use of a nonionic surfactant, such as
R.sub.f.sup.1--CH.sub.2CH.sub.2- --O--(CH.sub.2CH.sub.2O).sub.11--H
wherein R.sub.f.sup.1 is a C.sub.3-18 perfluoroalkyl group is
preferred.
[0022] A variety of additives, including inorganic and organic
fillers, antioxidants, heat stabilizers, ultraviolet absorbers,
lubricants, waxes, colorants and crystallization promoters, either
independently or combinations of a plurality thereof may be
used.
[0023] The emulsion can be used as is or, if necessary, after
dilution or other modification to the desired concentration, by
application to the fibers or textile products according to the
invention using any means known to one skilled in the art and most
suitable to the processing operation carried out in each case such
as, for example, impregnation, dipping, coating, or spraying. The
emulsion-treated fibers or textile products can be heat-treated at
about 150 to about 500, preferably 200 to 450.degree. C., and more
preferably at least 250 to 400.degree. C. for about 1 minute to
about 10 hours, thereby bringing to completion not only hydrolysis
of the fluorocarbon silane or hydrolysis of the fluorocarbon silane
and hydrolysis of the alkoxysilane, but also copolycondensation of
the hydrolyzate. A thin film containing a copolycondensate of a
fluorocarbon silane, or its hydrolyzate, and an alkoxysilane can be
formed. The heat treatment temperature and time period are
preferably set to the optimal values after taking into
consideration such factors as the heat resistance of the target
fibers or textile product and the cost effectiveness of treatment.
The preferred heat treatment temperature or time differs according
to the fibers and the textile product. In the case of
poly(p-phenylene terephthalamide) fibers, following application of
the emulsion, it is especially preferable to carry out heat
treatment at about 250.degree. C. for about 30 minutes. The ratio
of the weight of the copolycondensate coated onto the surface of
the high-strength fibers, relative to the weight of the
high-strength, heat-resistant organic fibers, is expressed in the
dry state following heat treatment and is referred to herein as the
"thin film-forming agent picku". This value is generally about 0.1
to 10%. Water generally makes up the rest of the emulsion.
[0024] The thickness of the thin film is a calculated value
computed from the thin film-forming agent pickup and based on the
assumption that the fiber cross section, which is generally
approximately circular, is a true circle. For example, if the thin
film-forming agent pickup (based on the fiber weight) is 2% and the
fabric weight is 16.7 g, the weight of the coating layer is
16.7.times.0.02=0.334 g. If the KEVLAR.RTM. yarn used in the
invention has a density per filament of 1.67 decitex, a length of
100,000 m, and the fibers in the yarn have a circular cross-section
and a cross-sectional diameter of 12 .mu.m, the entire surface area
is about 3.7680 m.sup.2 (37,680 cm.sup.2). Assuming that a thin
film of the above-described copolycondensate having a specific
gravity when dry of about 2 g/cm.sup.3 is uniformly coated over
this surface portion, the thin film has a thickness of 44.3 nm.
[0025] Before carrying out the above-described emulsion treatment
on the fibers or textile product, if necessary or desired,
extraneous substances such as finish may be removed from the
surface of the fibers by a scouring or solvent scouring operation.
Moreover, following the completion of thin film heat treatment, an
operation such as a washing operation to remove residual catalyst
and surfactant may be carried out by any means known to one skilled
in the art such as water or solvent extraction. Also, the various
above-described additives may be suitably added.
[0026] In the practice of the present invention, aside from using
high-strength, heat-resistant organic fibers to which has already
been applied a thin film of preferably at most 1,000 nm thickness
which comprises primarily a fluorocarbon silane or its hydrolyzate,
and/or a copolycondensate of a fluorocarbon silane with an
alkoxysilane, the invention can also treat with the above-described
copolycondensate textile products such as woven fabric composed of
the above high-strength heat-resistant organic fibers, protective
clothing made of such woven fabric, or protective gloves
manufactured directly from the fibers, thereby forming a thin film
on the surface of the fibers making up these textile products. Even
in cases where formation of the above-described thin film on the
fiber surfaces or the surface of the textile product involves
formation of the thin film on only a portion of the fiber surface
or a portion of the textile product surface, such fibers or
textiles products shall be regarded as within the scope of the
present invention.
EXAMPLES
[0027] Examples are given below by way of illustration, although
the invention is not limited by these examples.
[0028] The fluorocarbon silane used was a mixture of perfluoroalkyl
compounds having the formula
R.sub.f--(CH.sub.2).sub.2--Si{--(O--CH.sub.2-
CH.sub.2).sub.2--OCH.sub.3}.sub.3 wherein R.sub.f is
F(CF.sub.2).sub.k. The compound in which the letter k was 6
accounted for 1 to 2 wt % of the mixture, the compound in which k
was 8 accounted for 62 to 64 wt %, the compound in which k was 10
accounted for 23 to 30 wt %, and compounds in which k was 12 to 18
accounted for 2 to 6 wt % of the mixture.
[0029] The surfactant was a nonionic surfactant of the formula
R.sub.f'--CH.sub.2CH.sub.2--O--(CH.sub.2CH.sub.2O).sub.11--H
wherein R.sub.f' was a perfluoroalkyl group of 3 to 18 carbons.
[0030] The organoalkoxysilane was methyltrimethoxysilane
(CH.sub.3)Si(OCH.sub.3).sub.3.
Example 1
Preparation of a Fluorocarbon Silane/Alkoxysilane Emulsion
[0031] One hundred parts by weight of a fluorocarbon silane and 30
parts by weight of surfactant were dissolved in water. To the
resulting aqueous emulsion was slowly added, under stirring by a
conventional stirring technique, 2.5 wt % of the fluorocarbon
silane, based on the overall weight of the emulsion, thereby
suppressing self-condensation of the fluorocarbon silane and
maintaining it in a hydrolyzed state. Next, while measuring the pH
of the emulsion with a pH meter, phosphoric acid was added and
addition was brought to completion when the pH became 3. Also,
methyltrimethoxysilane (CH.sub.3)Si(OCH.sub.3).sub.3 was added such
as to make the molar fraction of the organoalkoxysilane with
respect to the fluorocarbon silane 0.45 and stirring was carried
out for 4 hours, yielding a fluorocarbon silane/alkoxysilane
emulsion.
[0032] Preparation of the Textile Product.
[0033] Three strands of 295 dtex (density per filament, 1.67
decitex), 20 s/1 two-ply yarn spun from poly(p-phenylene
terephthalamide) staple fiber (made by Du Pont-Toray Co., Ltd.,
Tokyo, under the trademark KEVLAR.RTM.) were paralleled and fed to
an SFG-10 gauge-type glovemaking machine (manufactured by Shima
Seiki Mfg., Ltd., Wakayama Prefecture) and knit into 10-gauge
gloves. The resulting gloves were ordinarily laundered using a
commercial neutral detergent, and dried. Next, the gloves were
immersed in the prepared fluorocarbon silane/alkoxysilane emulsion,
then lightly wrung by hand so as to adjust the pickup of emulsion
non-volatiles to 1%, based on the weight of the glove. Assuming
that the fiber cross-section was circular, the film thickness, as
computed from the thin film-forming agent pickup, was 22 nm. The
gloves were held in a 250.degree. C. oven for 30 minutes to effect
heat treatment and curing. The gloves were then taken out of the
oven and cooled to room temperature, after which they were washed
in tepid water and dried. The treated gloves showed no change in
hand or appearance compared with prior to treatment. However, when
the treated gloves were sprayed with water, the drops of water
scattered. The treated gloves demonstrated a striking difference in
water repellency compared with untreated gloves.
Example 2
Preparation of Woven Product
[0034] KEVLAR 29.RTM. yarn (made by Du Pont-Toray Co., Ltd., Tokyo)
having a density per filament of 1.67 decitex and composed of 2,000
filaments was used to manufacture plain-weave fabric having a warp
density of 17.5 ends/25 mm, a weft density of 16.8 picks/25 mm, and
a basis weight of 444 g/m.sup.2. A 5.times.5 cm square of the
resulting woven fabric was immersed for 5 minutes in the prepared
fluorocarbon silane/alkoxysilane emulsion, following which it was
drawn out and wrung free of excess fluid so as to adjust the pickup
of emulsion non-volatiles, based on the weight of the fabric
square, to 1%. This woven fabric was held in a 250.degree. C. oven
for 30 minutes to effect heat treatment and curing. As in Example
1, the film thus obtained had a thickness of about 22 nm.
Test Example
[0035] (1) Water and Oil Repellency
[0036] Drops of pure water and hexadecane were deposited in
respective amounts of 2 .mu.l onto the surface of the cured fabric
obtained in Example 2, and the contact angle of each fluid was
measured with a contact angle meter (manufactured by Kyowa
Interface Science Co., Ltd., Saitama Prefecture). The test results
are shown in Table 1 below.
[0037] In addition, a comparative example was carried out in which
drops of pure water and hexadecane were deposited in respective
amounts of 2 .mu.l onto the surface of woven fabric produced by the
method described in Example 2, but not treated with the
fluorocarbon silane/alkoxysilane emulsion. The contact angle of
each fluid was measured. The test results are shown in Table 1
below.
1TABLE 1 Water and Oil Repellency Example 2 Comparative Example
Water 124.degree. not measurable due to penetration of water
Hexadecane 109.degree. not measurable due to penetration of
hexadecane
[0038] A comparison of the results obtained for woven fabric in
Example 2 with the results obtained for the woven fabric in the
comparative example showed that water and hexadecane penetrated the
untreated fabric, making it impossible to measure the contact
angle. By contrast, in Example 2 in which the test was carried out
on a fabric treated with fluorocarbon silane/alkoxysilane emulsion,
the fabric exhibited high water and oil repellencies.
[0039] (2) Heat Resistance
[0040] The treated woven fabric was placed in a 250.degree. C. oven
and the contact angle was measured after the period of time shown
in Table 2 had elapsed. The test results are shown in Table 2.
2TABLE 2 Heat Resistance Example 2 Initial water contact angle
(degrees) 124 Water contact angle after 3 hours at 250.degree. C.
(degrees) 127 Water contact angle after 24 hours at 250.degree. C.
(degrees) 128
[0041] The above results showed that, in Example 2, a high water
repellency was maintained even after 24 hours at 250.degree. C.
[0042] (3) Stainproof Properties
[0043] One drop of automotive engine oil (engine oil actually used
in an automobile for about 1,000 km) was deposited with a pipette
in each of three places on a treated woven fabric and an untreated
woven fabric, following which the fabrics were allowed to stand for
one hour. Laundry detergent (produced by Kao Corporation, Tokyo
under the trade name ATTACK) was dissolved in running water to a
standard usage concentration of 0.083 wt %. The engine oil-bearing
woven fabrics were placed in the synthetic detergent solution and
agitated for 5 minutes, then rinsed with running water for 1
minute. Upon comparing the appearances of both types of sample, the
oil stain that penetrated the untreated product was found not to
have disappeared but the oil stain in the treated product had
disappeared completely. Moreover, sufficient water repellency was
maintained in the laundered fabric.
[0044] The above results show that the present invention provides
high-strength, heat-resistant organic fibers endowed with excellent
heat resistance and durability and also an excellent stainproofing
performance with no loss of hand. By using such fibers according to
the invention, there can be obtained textile products such as
firefighting apparel or gloves which, in addition to having
excellent cut resistance, flame resistance and dimensional
stability at high temperatures, are coated on the fiber surfaces
with a water and oil-repelling thin film. Such textile products are
resistant to staining and easy to clean. Moreover, because the thin
film has a very small thickness, textile products can be obtained
in which the characteristics inherent to the constituent fibers,
such as their hand, are essentially retained with little or no
loss. Furthermore, the invention provides a method capable of
manufacturing the above-described fibers and textile products,
which method readily imparts a high stainproofing performance due
to such water and oil repellency without any loss in the
characteristics inherent to high-strength, heat-resistant organic
fibers, such as the hand.
* * * * *