U.S. patent application number 13/881457 was filed with the patent office on 2013-08-15 for flame resistant spun staple yarns made from blends of fibers derived from sulfonated polyoxadiazole polymers.
This patent application is currently assigned to E I DU PONT DE NEMOURS AND COMPANY. The applicant listed for this patent is Michael W. Cobb, Sharlene Renee Williams, Reiyao Zhu. Invention is credited to Michael W. Cobb, Sharlene Renee Williams, Reiyao Zhu.
Application Number | 20130210306 13/881457 |
Document ID | / |
Family ID | 45418795 |
Filed Date | 2013-08-15 |
United States Patent
Application |
20130210306 |
Kind Code |
A1 |
Cobb; Michael W. ; et
al. |
August 15, 2013 |
FLAME RESISTANT SPUN STAPLE YARNS MADE FROM BLENDS OF FIBERS
DERIVED FROM SULFONATED POLYOXADIAZOLE POLYMERS
Abstract
Described is a flame-resistant spun yarn having: about 50 to
about 95 parts by weight of a sulfonated polyoxadiazole based
staple fiber comprising repeat units of Formula (I) and one or both
of Formula (II) and (IIa): ##STR00001## wherein M is a cation; and
about 5 to about 50 parts by weight of a textile staple fiber
having limiting oxygen index of 21 or greater and a tenacity of
about 4 grams per denier or greater, based on the total amount of
the polymeric fiber and the textile fiber in the yarn.
Inventors: |
Cobb; Michael W.;
(Wilmington, DE) ; Williams; Sharlene Renee;
(Wilmington, DE) ; Zhu; Reiyao; (Moseley,
VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cobb; Michael W.
Williams; Sharlene Renee
Zhu; Reiyao |
Wilmington
Wilmington
Moseley |
DE
DE
VA |
US
US
US |
|
|
Assignee: |
E I DU PONT DE NEMOURS AND
COMPANY
Wilmington
DE
|
Family ID: |
45418795 |
Appl. No.: |
13/881457 |
Filed: |
December 5, 2011 |
PCT Filed: |
December 5, 2011 |
PCT NO: |
PCT/US2011/063273 |
371 Date: |
April 25, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61423616 |
Dec 16, 2010 |
|
|
|
61423620 |
Dec 16, 2010 |
|
|
|
Current U.S.
Class: |
442/302 ; 2/338;
2/455; 442/414; 57/243 |
Current CPC
Class: |
A41D 31/08 20190201;
Y10T 442/3984 20150401; Y10T 442/696 20150401; D02G 3/443
20130101 |
Class at
Publication: |
442/302 ; 2/455;
442/414; 57/243; 2/338 |
International
Class: |
D02G 3/44 20060101
D02G003/44; A41D 31/00 20060101 A41D031/00 |
Claims
1. A flame-resistant spun yarn comprising: about 50 to about 95
parts by weight of a sulfonated polyoxadiazole based staple fiber
comprising repeat units of Formula (I) and one or both of Formula
(II) and (IIa): ##STR00007## wherein M is a cation; and about 5 to
about 50 parts by weight of either a textile staple fiber having
limiting oxygen index of 21 or greater and a tenacity of about 4
grams per denier or greater, based on the total amount of the
polymeric fiber and the textile fiber in the yarn, or a high
modulus staple fiber having a tensile modulus of 200 grams per
denier or greater, based on the total amount of the polymeric fiber
and the high modulus fiber in the yarn.
2. A protective garment, woven fabric, nonwoven fabric, belt, or
filament comprising the flame-resistant spun yarn of claim 1.
3. A flame-resistant spun yarn comprising: at least about 25 parts
to about 80 parts by weight of a sulfonated polyoxadiazole based
staple fiber comprising repeat units of Formula (I) and one or both
of Formula (II) and (IIa): ##STR00008## wherein M is a cation; and
about 20 to about 75 parts by weight of a modacrylic fiber, based
on the total amount of the polymeric fiber and the textile fiber in
the yarn.
4. A protective garment, woven fabric, nonwoven fabric, belt, or
filament comprising the flame-resistant spun yarn of claim 3.
5.-12. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of priority of U.S.
Provisional Application Nos. 61/423,616 and 61/423,620, filed on
Dec. 16, 2010, the entirety of which is herein incorporated by
reference.
FIELD OF THE INVENTION
[0002] The invention relates to flame-resistant spun staple yarns,
and fabrics and garments comprising these yarns, and methods of
making the same. The yarns contain a blend of polymeric staple
fiber containing sulfonated polyoxadiazole polymers.
BACKGROUND
[0003] Workers that can be exposed to flames, high temperatures,
and/or electrical arcs and the like, need protective clothing and
articles made from thermally resistant fabrics. Any increase in the
effectiveness of these protective articles, or any increase in the
comfort, durability, and dyeability of these articles while
maintaining protection performance, is welcomed.
[0004] Polyoxadiazole polymers have unique properties and are
useful in many fields, for example high performance fibers, such as
flame retardant fibers. One method to improve flammability is to
prepare sulfonated polyoxadiazole polymers. These methods have
included the use of sulfonated monomers and post-sulfonation. Gomes
et al. (US 20098/0318109, US2008/0193652, US2009/0203870) reacted
hydrazine sulfate and aromatic dicarboxylic acids in phosphoric
acid to form mono-sulfonated polyoxadiazole copolymers, and
subsequently post-sulfonated the polymer. Another method is the use
of oleum during polymerization to sulfonate the polymer as it is
prepared. Lee et al. (U.S. Pat. No. 7,528,216 and U.S. Pat. No.
7,582,721) prepared random polyoxadiazole copolymers by reacting
aromatic dicarboxylic acids with hydrazine sulfate in a limited
amount of oleum, and prepared sulfonated random polyoxadiazole
copolymers using sulfonated monomers (U.S. Pat. No. 7,528,217).
[0005] Therefore what is needed is a way of incorporating
sulfonated polyoxadiazole into yarns for use in protective apparel
that utilizes the benefits of the sulfonated polyoxadiazole fiber
with improved properties, such as flame retardancy and
dyeability.
SUMMARY
[0006] Disclosed is a flame-resistant spun yarn comprising about 50
to about 95 parts by weight of a sulfonated polyoxadiazole based
staple fiber comprising repeat units of Formula (I) and one or both
of Formula (II) and (IIa):
##STR00002##
[0007] wherein M is a cation; and about 5 to about 50 parts by
weight of a textile staple fiber having limiting oxygen index of 21
or greater and a tenacity of about 4 grams per denier or greater,
based on the total amount of the polymeric fiber and the textile
fiber in the yarn.
[0008] Also disclosed is a flame-resistant spun yarn comprising at
least about 25 parts to about 80 parts by weight of a sulfonated
polyoxadiazole based staple fiber comprising repeat units of
Formula (I) and one or both of Formula (II) and (IIa), wherein M is
a cation; and about 20 to about 75 parts by weight of a modacrylic
fiber, based on the total amount of the polymeric fiber and the
textile fiber in the yarn.
[0009] Also disclosed is a flame-resistant spun yarn comprising
about 50 to about 95 parts by weight of a sulfonated polyoxadiazole
based staple fiber comprising repeat units of Formula (I) and one
or both of Formula (II) and (IIa) wherein M is a cation; and about
5 to about 50 parts by weight of a high modulus staple fiber having
a tensile modulus of 200 grams per denier or greater, based on the
total amount of the polymeric fiber and the textile fiber in the
yarn.
[0010] Also disclosed is a flame-resistant spun yarn comprising
about 20 to about 50 parts by weight of a sulfonated polyoxadiazole
based staple fiber comprising repeat units of Formula (I) and one
or both of Formula (II) and (IIa) wherein M is a cation; and about
50 to about 80 parts by weight of a rigid-rod staple fiber, based
on the total amount of the sulfonated polyoxadiazole based fiber
and the textile fiber in the yarn.
[0011] Also disclosed is a protective garment, woven fabric,
nonwoven fabric, belt, or filament comprising the flame-resistant
spun yarns.
[0012] Disclosed herein is a method of producing a spun yarn
comprising:
a) forming a fiber mixture of about 50 to about 95 parts by weight
of a polyoxadiazole based staple fiber comprising repeat units of
Formula (I) and one or both of Formula (II) and (IIa) wherein M is
a cation; and about 5 to about 50 parts by weight of a textile
staple fiber having limiting oxygen index of 21 or greater and a
tenacity of about 4 grams per denier or greater, based on the total
amount of the polymeric fiber and the textile fiber in the yarn;
and b) spinning the fiber mixture into a spun staple yarn.
[0013] Also disclosed is a method of producing a spun yarn
comprising: a) forming a fiber mixture of at least about 25 parts
by weight of a polyoxadiazole based staple fiber comprising repeat
units of Formula (I) and one or both of Formula (II) and (IIa)
wherein M is a cation; and about 20 to about 75 parts by weight of
a modacrylic fiber, based on the total amount of the polymeric
fiber and the textile fiber in the yarn; and b) spinning the fiber
mixture into a spun staple yarn.
[0014] Also disclosed is a method of producing a spun yarn
comprising: a) forming a fiber mixture of about 50 to about 95
parts by weight of a polyoxadiazole based staple fiber comprising
repeat units of Formula (I) and one or both of Formula (II) and
(IIa) wherein M is a cation; and about 5 to about 50 parts by
weight of a high modulus staple fiber having a tensile modulus of
200 grams per denier or greater, based on the total amount of the
polymeric fiber and the textile fiber in the yarn; and b) spinning
the fiber mixture into a spun staple yarn.
[0015] Also disclosed is a method of producing a spun yarn
comprising: a) forming a fiber mixture of about 20 to about 50
parts by weight of a polyoxadiazole based staple fiber comprising
repeat units of Formula (I) and one or both of Formula (II) and
(IIa) wherein M is a cation; and about 50 to about 80 parts by
weight of a rigid-rod staple fiber, based on the total amount of
the polymeric fiber and the textile fiber in the yarn; and b)
spinning the fiber mixture into a spun staple yarn.
DETAILED DESCRIPTION
[0016] Disclosed is a flame-resistant spun yarn comprising:
[0017] about 50 to about 95 parts by weight of a sulfonated
polyoxadiazole based staple fiber comprising repeat units of
Formula (I) and one or both of Formula (II) and (IIa):
##STR00003##
[0018] wherein M is a cation;
and about 5 to about 50 parts by weight of a textile staple fiber
having limiting oxygen index of 21 or greater and a tenacity of
about 4 grams per denier or greater, based on the total amount of
the polymeric fiber and the textile fiber in the yarn.
[0019] In one embodiment the sulfonated polyoxadiazole based staple
fiber is present at about 50 to about 85, or about 50 to about 75,
or about 60 to about 85, or about 70 to about 80 parts by weight,
and the high modulus staple fiber is present at about 15 to about
50, or about 25 to about 40, or about 15 to about 40, or about 20
to about 30 parts by weight.
[0020] Suitable textile fibers include meta-aramid fibers,
para-aramid fibers, and polyazole fibers.
[0021] Also disclosed is a flame-resistant spun yarn comprising at
least about 25 parts to about 80 parts by weight of a sulfonated
polyoxadiazole based staple fiber comprising repeat units of
Formula (I) and one or both of Formula (II) and (IIa) wherein M is
a cation; and about 20 to about 75 parts by weight of a modacrylic
fiber, based on the total amount of the polymeric fiber and the
textile fiber in the yarn.
[0022] In one embodiment the sulfonated polyoxadiazole based staple
fiber is present at about 35 to about 70, or about 50 to about 75
parts by weight, or about 45 to about 60, or about 45 to about 70
parts by weight, and the modacrylic fiber is present at about 30 to
about 65, or about 25 to about 50, or about 40 to about 55, or
about 30 to about 55 parts by weight.
[0023] Suitable modacrylic fibers include copolymers of
acrylonitrile combined with vinylidene chloride.
[0024] Also disclosed is a flame-resistant spun yarn comprising at
least about 50 to about 95 by weight of a sulfonated polyoxadiazole
based staple fiber comprising repeat units of Formula (I) and one
or both of Formula (II) and (IIa) wherein M is a cation; and about
5 to about 50 parts by weight of a high modulus staple fiber having
a tensile modulus of 200 grams per denier or greater, based on the
total amount of the polymeric fiber and the textile fiber in the
yarn.
[0025] In one embodiment the sulfonated polyoxadiazole based staple
fiber is present at about 50 to about 85, or about 50 to about 75,
or about 60 to about 85, or about 70 to about 80 parts by weight,
and the high modulus staple fiber is present at about 15 to about
50, or about 25 to about 40, or about 15 to about 40, or about 20
to about 30 parts by weight.
[0026] Many different fibers can be used as the high modulus staple
fiber, including para-aramid fibers, polyazole fibers, carbon
fibers, and mixtures thereof. In some embodiments para-aramid fiber
can be used in the blend as the high modulus staple fiber. By
aramid is meant a polyamide wherein at least 85% of the amide
(--CONH--) linkages are attached directly to two aromatic rings.
Additives can be used with the aramid and, in fact, it has been
found that up to as much as 10 percent, by weight, of other
polymeric material can be blended with the aramid or that
copolymers can be used having as much as 10 percent of other
diamine substituted for the diamine of the aramid or as much as 10
percent of other diacid chloride substituted for the diacid
chloride of the aramid. In some embodiments, the preferred
para-aramid is poly(paraphenylene terephthalamide). Methods for
making para-aramid fibers useful are generally disclosed in, for
example, U.S. Pat. Nos. 3,869,430; 3,869,429; and 3,767,756.
Various forms of such aromatic polyamide organic fibers are sold
under the trademarks of Kevlar.RTM. and Twaron.RTM. by
respectively, E. I. du Pont de Nemours and Company, of Wilmington,
Del.; and Teijin, Ltd, of Japan. Also, fibers based on
copoly(p-phenylene/3,4'-diphenyl ether terephthalamide) are defined
as para-aramid fibers as used herein. One commercially available
version of these fibers is known as Technora.RTM. fiber also
available from Teijin, Ltd.
[0027] In some embodiments polyazole fibers can be used as the high
modulus fiber in the blend. For example, suitable polyazoles
include polybenzazoles, polypyridazoles, and the like, and can be
homopolymers or copolymers. Additives can be used with the
polyazoles and up to as much as 10 percent, by weight, of other
polymeric material can be blended with the polyazoles. Also
copolymers can be used having as much as 10 percent or more of
other monomer substituted for a monomer of the polyazoles. Suitable
polyazole homopolymers and copolymers can be made by known
procedures, such as those described in U.S. Pat. No. 4,533,693 (to
Wolfe, et al., on Aug. 6, 1985), U.S. Pat. No. 4,703,103 (to Wolfe,
et al., on Oct. 27, 1987), U.S. Pat. No. 5,089,591 (to Gregory, et
al., on Feb. 18, 1992), U.S. Pat. No. 4,772,678 (Sybert, et al., on
Sep. 20, 1988), U.S. Pat. No. 4,847,350 (to Harris, et al., on Aug.
11, 1992), and U.S. Pat. No. 5,276,128 (to Rosenberg, et al., on
Jan. 4, 1994).
[0028] In some embodiments the preferred polybenzazoles are
polybenzimidazoles, polybenzothiazoles, and polybenzoxazoles. If
the polybenzazole is a polybenzimidazole, preferably it is
poly[5,5'-bi-1H-benzimidazole]-2,2'-diyl-1,3-phenylene which is
called PBI. If the polybenzazole is a polybenzothiazole, preferably
it is a polybenzobisthiazole and more preferably it is
poly(benzo[1,2-d:4,5-d']bisthiazole-2,6-diyl-1,4-phenylene which is
called PBT. If the polybenzazole is a polybenzoxazole, preferably
it is a polybenzobisoxazole and more preferably it is
poly(benzo[1,2-d:4,5-d']bisoxazole-2,6-diyl-1,4-phenylene which is
called PBO.
[0029] In some embodiments the preferred polypyridazoles are
rigid-rod polypyridobisazoles including poly(pyridobisimidazole),
poly(pyridobisthiazole), and poly(pyridobisoxazole). The preferred
poly(pyridobisoxazole) is
poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d']bisimidazole
which is called PIPD. Suitable polypyridobisazoles can be made by
known procedures, such as those described in U.S. Pat. No.
5,674,969. High modulus carbon fibers are well known in the art and
commercially available carbon fibers include Tenax.RTM. fibers
available from Toho Tenax America, Inc.
[0030] In some preferred embodiments, the high modulus staple fiber
has a limiting oxygen index (LOI) of 21 or greater, meaning the
high modulus staple fiber or fabrics made solely from the high
modulus staple fiber will not support a flame in air. In some
preferred embodiments the high modulus staple fiber has a LOI of at
least 26 or greater.
[0031] In some embodiments, the high modulus staple fiber has a
break tenacity of at least 5 grams per denier (4.5 grams per dtex)
or greater. In some other embodiments the high modulus staple fiber
has a break tenacity of at least 10 grams per denier (9 grams per
dtex) or greater. The addition of the higher tenacity high modulus
staple fiber provides the spun yarn with additional strength that
translates into improved strength and durability in the final
fabrics and garments made from the spun yarns. Also, in some cases,
depending on the blending percentage, it is believed the additional
tenacity provided by the high modulus staple fiber to the spun yarn
is magnified in the fabrics and garments made from the yarn,
resulting in more tenacity improvement in the fabric than in the
spun yarn.
[0032] Also disclosed is a flame-resistant spun yarn comprising at
least about 20 to about 50 parts by weight of a sulfonated
polyoxadiazole based staple fiber comprising repeat units of
Formula (I) and one or both of Formula (II) and (IIa) wherein M is
a cation; and about 50 to about 80 parts by weight of a rigid-rod
staple fiber based on the total amount of the polymeric fiber and
the textile fiber in the yarn.
[0033] In one embodiment the sulfonated polyoxadiazole based staple
fiber is present at about 30 to about 40, or about 35 to about 40,
or about 30 to about 50, or about 20 to 40 parts by weight, and the
rigid-rod staple fiber is present at about 60 to about 70, or about
60 to about 65, or about 50 to about 70, or about 60 to about 80
parts by weight. For purposes herein, "rigid-rod fiber" means
fibers made from rigid-rod aromatic polymers having what are known
in the art as rigid spacer segments; these rigid-rod fibers also
form fibrils with abrasion or wear. The rigid spacers often contain
another cyclic unit, or functional end groups such as --NH--,
--CO--, --O--, --COO--, --N.dbd.N--, and/or --CH.dbd.CH--.
Generally these rigid-rod polymers have highly para-oriented
aromatic groups and the fibers made from these polymers have a high
tensile modulus. With wear or abrasion, rigid-rod fibers readily
fibrillate; that is, they form structures having a central fiber
stalk with fibrils extending therefrom. The stalk is generally
columnar and 4 to 50 microns in diameter and the fibrils are
hair-like members only a fraction of a micron or a few microns in
diameter attached to the stalk and are 10 to 100 microns long.
[0034] Different fibers can be used as the rigid-rod staple fiber.
In some embodiments para-aramid fiber can be used in the blend as
the rigid-rod staple fiber. By "aramid" is meant a polyamide
wherein at least 85% of the amide (--CONH--) linkages are attached
directly to two aromatic rings. Additives can be used with the
aramid and, in fact, it has been found that up to as much as 10
percent, by weight, of other polymeric material can be blended with
the aramid or that copolymers can be used having as much as 10
percent of other diamine substituted for the diamine of the aramid
or as much as 10 percent of other diacid chloride substituted for
the diacid chloride of the aramid. In some embodiments, the
preferred para-aramid is poly(paraphenylene terephthalamide).
Methods for making para-aramid fibers useful are generally
disclosed in, for example, U.S. Pat. Nos. 3,869,430; 3,869,429; and
3,767,756. Various forms of such aromatic polyamide organic fibers
are sold under the trademarks of Kevlar.RTM. and Twaron.RTM. by
respectively, E. I. du Pont de Nemours and Company, of Wilmington,
Del.; and Teijin, Ltd, of Japan. Also, fibers based on
copoly(p-phenylene/3,4'-diphenyl ether terephthalamide) are defined
as para-aramid fibers as used herein. One commercially available
version of these fibers is known as Technora.RTM. fiber also
available from Teijin, Ltd.
[0035] In some embodiments, polyazole fibers can be used as the
rigid-rod fiber in the blend. For example, suitable polyazoles
include polybenzazoles, polypyridazoles, and the like, and can be
homopolymers or copolymers. Additives can be used with the
polyazoles and up to as much as 10 percent, by weight, of other
polymeric material can be blended with the polyazoles. Also
copolymers can be used having as much as 10 percent or more of
other monomer substituted for a monomer of the polyazoles. Suitable
polyazole homopolymers and copolymers can be made by known
procedures, such as those described in U.S. Pat. No. 4,533,693 (to
Wolfe, et al., on Aug. 6, 1985), U.S. Pat. No. 4,703,103 (to Wolfe,
et al., on Oct. 27, 1987), U.S. Pat. No. 5,089,591 (to Gregory, et
al., on Feb. 18, 1992), U.S. Pat. No. 4,772,678 (Sybert, et al., on
Sep. 20, 1988), U.S. Pat. No. 4,847,350 (to Harris, et al., on Aug.
11, 1992), and U.S. Pat. No. 5,276,128 (to Rosenberg, et al., on
Jan. 4, 1994). In some embodiments the preferred polybenzazoles are
polybenzimidazoles, polybenzothiazoles, and polybenzoxazoles. If
the polybenzazole is a polybenzimidazole, preferably it is
poly[5,5'-bi-1H-benzimidazole]-2,2'-diyl-1,3-phenylene which is
called PBI. If the polybenzazole is a polybenzothiazole, preferably
it is a polybenzobisthiazole and more preferably it is
poly(benzo[1,2-d:4,5-d']bisthiazole-2,6-diyl-1,4-phenylene which is
called PBT. If the polybenzazole is a polybenzoxazole, preferably
it is a polybenzobisoxazole and more preferably it is
poly(benzo[1,2-d:4,5-d']bisoxazole-2,6-diyl-1,4-(phenylene) which
is called PBO.
[0036] In some embodiments the preferred polypyridazoles are
rigid-rod polypyridobisazoles including poly(pyridobisimidazole),
poly(pyridobisthiazole), and poly(pyridobisoxazole). The preferred
poly(pyridobisoxazole) is
poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d']bisimidazole
which is called PIPD. Suitable polypyridobisazoles can be made by
known procedures, such as those described in U.S. Pat. No.
5,674,969.
[0037] In some embodiments, the spun staple yarns can also include
a rigid-rod staple fiber having a limiting oxygen index (LOI) of 21
or greater, meaning the rigid-rod staple fiber or fabrics made
solely from the rigid-rod staple fiber will not support a flame in
air. In some preferred embodiments the rigid-rod staple fiber has a
LOI of at least 26 or greater.
[0038] In some embodiments, the rigid-rod staple fiber has a break
tenacity of at least 5 grams per denier (4.5 grams per dtex) or
greater. In some other embodiments the rigid-rod staple fiber has a
break tenacity of at least 10 grams per denier (9 grams per dtex)
or greater. The addition of the higher tenacity rigid-rod staple
fiber provides the spun yarn with additional strength that
translates into improved strength and durability in the final
fabrics and garments made from the spun yarns. Also, in some cases,
it is believed the additional tenacity provided by the rigid-rod
staple fiber to the spun yarn is magnified in the fabrics and
garments made from the yarn, resulting in more tenacity improvement
in the fabric than in the spun yarn.
[0039] Also disclosed is a flame-resistant spun yarn comprising at
least about 50 to about 95 parts by weight of a sulfonated
polyoxadiazole based staple fiber comprising repeat units of
Formula (I) and one or both of Formula (II) and (IIa) wherein M is
a cation; and about 5 to about 50 parts by weight of a textile
staple fiber having limiting oxygen index of 21 or greater and a
tenacity of about 4 grams per denier or greater, based on the total
amount of the polymeric fiber and the textile fiber in the
yarn.
[0040] In one embodiment the sulfonated polyoxadiazole based staple
fiber is present at about 50 to about 85, or about 50 to about 75,
or about 60 to about 85, or about 70 to about 80 parts by weight,
and the high modulus staple fiber is present at about 15 to about
50, or about 25 to about 40, or about 15 to about 40, or about 20
to about 30 parts by weight.
[0041] In the flame-resistant spun yarns disclosed herein, M is
typically a monovalent cation such as H, Li, Na, K, or NH.sub.4. In
some embodiments Formula (I) is present at about 5 molar % to about
50 molar %, or about 5 molar % to about 40 molar %, or about 10
molar % to about 30 molar %, and one or both of Formula (II) and
(IIa) is present at about 50 molar % to about 95 molar %, or about
60 molar % to about 95 molar %, or about 70 molar % to about 90
molar %, based on the total amount of sulfonated polyoxadiazole
based staple fiber. In other embodiments Formula (II) is used in
about 60 to about 95 molar %, or about 70 to about 90 molar %; and
Formula (IIa) is used in about 0 to about 30 molar %, or about 0 to
about 20 molar %. In yet other embodiments, Formula (II) is not
present or Formula (IIa) is not present.
[0042] M can be converted to another M at any time, either before
or after spinning or formation into a shaped article. When M is H,
the polymer can be neutralized by contact with a salt, such as but
not limited to sodium bicarbonate, sodium hydroxide, cesium
hydroxide, lithium hydroxide, potassium hydroxide, or potassium
carbonate. The ion exchange and/or neutralization can be performed
by any method known in the art.
[0043] The sulfonated polyoxadiazole based staple fiber can further
comprise repeat units of other moieties in the polymer chain. These
repeat units can comprise one or both of Formula (III) and Formula
(IIIa):
##STR00004##
[0044] The sulfonated polyoxadiazole based staple fiber can have at
least about 2 weight %, 4 weight %, or 6 weight % sulfur content.
The amount of sulfur can be increased by sulfonation of the
monomers before polymerization, or sulfonation of the polymer.
[0045] The polymer used to prepare the sulfonated polyoxadiazole
based staple fibers disclosed herein can be made by any method or
process known in the art. One suitable method comprises the steps
of: [0046] a. combining hydrazine, oleum, 4,4'-oxybis(benzoic
acid), and one or both of terephthalic acid and isophthalic acid,
to form a reaction mixture, wherein the oleum is added in an amount
of at least about 5 molar equivalents of SO.sub.3 based on the
number of moles of hydrazine; and [0047] b. heating the reaction
mixture to a temperature of about 100.degree. C. to about
180.degree. C. until a sulfonated copolyoxadiazole polymer is
prepared.
[0048] Other monomers may also be present in the reaction
mixture.
[0049] The process described herein can prepare sulfonated
polyoxadiazole polymers that comprise at least about 2 weight %, 4
weight %, or 6 weight % sulfur content. The amount of sulfur can be
increased by additional process steps in which the
4,4'-oxybis(benzoic acid), or one or both of terephthalic acid and
isophthalic acid are further sulfonated before polymerization,
and/or process steps in which the polyoxadiazole copolymer product
is sulfonated. This sulfonation can be performed by any method
known in the art that is not detrimental to the final product, such
as contact with oleum, sulfuric acid, or other sulfonation
agent.
[0050] Hydrazine can be used directly, or used in the form of a
solid hydrazine salt. One suitable solid salt is hydrazine sulfate,
[N.sub.2H.sub.5]HSO.sub.4, also called hydrazinium sulfate.
[0051] Oleum, also known as fuming sulfuric acid, disulfuric acid
or pyrosulfuric acid, refers to a solution of various compositions
of sulfur trioxide (SO.sub.3) in sulfuric acid. Typically 20-30%
oleum is used, more typically 30%, which refers to the weight % of
SO.sub.3 in the sulfuric acid. The oleum is added in an amount of
at least about 5 molar equivalents of SO.sub.3, or more typically
at least about 6 molar equivalents, based on the number of moles of
hydrazine.
[0052] The amounts of the reagents used is dependent on the desired
percentage of the repeat units in the final polymer. Based on the
total amount of dicarboxylic acids used, 4,4'-oxybis(benzoic acid)
(OBBA) is used in amounts of at about 1 molar % to about 50 molar
%, or about 5 molar % to about 50 molar %, or about 10 molar % to
about 30 molar %, and one or both of terephthalic acid and
isophthalic acid is used in amounts about 50 molar % to about 99
molar %, or about 50 molar % to about 95 molar %, or about 70 molar
% to about 90 molar %. In another embodiment terephthalic acid is
used in about 50 to about 90 molar %, or about 70 to about 80 molar
%; and isophthalic acid is used in about 0 to about 30 molar %, or
about 0 to about 20 molar %. In another embodiment, terephthalic
acid is not present or isophthalic acid is not present. Various
ratios of hydrazine can be could be used, but is typically used at
about a 1:1 molar ratio of dicarboxylic acids:hydrazine.
[0053] The ingredients can be combined in any order, but typically
the solid ingredients are first thoroughly mixed together and then
combined with the oleum. In one embodiment, the oleum is added in a
single step; that is, added in one aliquot. In another embodiment,
the oleum and OBBA can be mixed together prior to the addition of
the other dicarboxylic acids and hydrazine. The mixture is then
thoroughly mixed by stirring or other agitation means until
sufficiently dissolved, typically at least five minutes. This
dissolution can be performed at room temperature up to about
100.degree. C.
[0054] In one embodiment, the process comprises the steps of:
[0055] a1) combining hydrazine or salt thereof, 4,4'-oxybis(benzoic
acid), and one or both of terephthalic acid and isophthalic acid to
form a pre-mixture;
[0056] a2) stirring the pre-mixture for at least 5 minutes; and
[0057] a3) adding oleum to the pre-mixture in an amount of at least
about 5 molar equivalents of SO.sub.3 based on the number of moles
of hydrazine to form a reaction mixture.
[0058] After dissolution, the mixture is allowed to react until
sufficient polymer has formed. Typically the polymerization
reaction is performed at a temperature of about 100.degree. C. to
about 180.degree. C., or about 120.degree. C. to about 140.degree.
C., for at least about 0.5 hours. The temperature can be maintained
or increased or ramped up during the reaction. The temperature can
be used to control the amounts of sulfonation and type of
sulfonated repeating units in the final polymer. For instance, if
more sulfonation and/or ring-closed repeating units are desired
then the temperature should be increased, typically to greater than
about 120.degree. C. If less sulfonation and/or ring-closed
repeating units are desired then the temperature should be lower,
typically less than about 100.degree. C.
[0059] The sulfonated polyoxadiazole polymers prepared by the
process disclosed above can be neutralized either before or after
formation into a shaped article, so that the H cation is replaced
by another cation, typically a monovalent cation such as Li, Na, K,
or NH.sub.4. This is performed by contacting the sulfonated
polyoxadiazole polymer with a neutralization agent, typically a
basic salt such as sodium bicarbonate or other ion exchange
agent.
[0060] Also disclosed is a sulfonated copolyoxadiazole polymer
prepared by the process described herein, and shaped articles and
fibers made therefrom.
[0061] The polymers described herein can be formed into a shaped
article, such as films, fibrids, fibers for floc, and fibers for
textile uses, and for use in protective garments, woven fabrics,
nonwoven fabrics, papers, belts, or filaments. It can be spun into
fibers via solution spinning, using a solution of the polymer in
either the polymerization solvent or another solvent for the
polymer. Fiber spinning can be accomplished through a multi-hole
spinneret by dry spinning, wet spinning, or dry-jet wet spinning
(also known as air-gap spinning) to create a multi-filament yarn or
tow as is known in the art.
[0062] Shaped articles as described herein include extruded or
blown shapes or films, molded articles, and the like. Films can be
made by any known technique such as casting the dope onto a flat
surface, extruding the dope through an extruder to form a film or
extruding and blowing the dope film to form an extruded blown film.
Typical techniques for dope film extrusion include processes
similar to those used for fibers, where the solution passes through
a spinneret or die into an air gap and subsequently into a
coagulant bath. More details describing the extrusion and
orientation of a dope film can be found in Pierini et al. (U.S.
Pat. No. 5,367,042); Chenevey, (4,898,924); Harvey et al.,
(4,939,235); and Harvey et al., (4,963,428). Typically the dope
film prepared is preferably no more than about 250 mils (6.35 mm)
thick and more preferably it is at most about 100 mils (2.54 mm)
thick.
[0063] "Fiber" is defined as a relatively flexible, unit of matter
having a high ratio of length to width across its cross-sectional
area perpendicular to its length. Herein, the term "fiber" is used
interchangeably with the term "filament" or "end" or "continuous
filament". The cross section of the filaments described herein can
be any shape, such as circular or bean shaped, but is typically
generally round, and is typically substantially solid and not
hollow. Fiber spun onto a bobbin in a package is referred to as
continuous fiber. Fiber can be cut into short lengths called staple
fiber. Fiber can be cut into even smaller lengths called floc.
Yarns, multifilament yarns or tows comprise a plurality of fibers.
Yarn can be intertwined and/or twisted.
[0064] Fibers may be spun from solution using any number of
processes, however, wet spinning and air-gap spinning are the best
known. In wet spinning, the spinneret extrudes the fiber directly
into the liquid of a coagulation bath and typically the spinneret
is immersed or positioned beneath the surface of the coagulation
bath. In air-gap spinning (also sometimes known as "dry-jet" wet
spinning) the spinneret extrudes the fiber first into a gas, such
as air, for a very short duration and then the fiber is immediately
introduced into a liquid coagulation bath. Typically the spinneret
is positioned above the surface of the coagulation bath, creating
an "air-gap" between the spinneret face and the surface of the
coagulation bath. The general arrangement of the spinnerets and
baths is well known in the art, with the figures in U.S. Pat. Nos.
3,227,793; 3,414,645; 3,767,756; and 5,667,743 being illustrative
of such spinning processes for high strength polymers.
[0065] "Dry spinning" means a process for making a filament by
extruding a solution into a heated chamber having a gaseous
atmosphere to remove the solvent, leaving a solid filament. The
solution comprises a fiber-forming polymer in a solvent which is
extruded in a continuous stream through one or more spinneret holes
to orient the polymer molecules. This is distinct from "wet
spinning" or "air-gap spinning" wherein the polymer solution is
extruded into a liquid precipitating or coagulating medium to
regenerate the polymer filaments. In other words, in dry spinning a
gas is the primary solvent extraction medium, and in wet spinning a
liquid is the primary solvent extraction medium. In dry spinning,
after formation of solid filaments, the filaments can then be
treated with a liquid to either cool the filaments or wash the
filaments to further extract remaining solvent.
[0066] The fibers in the multi-filament yarn, or tow, after
spinning can then be treated to neutralize, wash, dry, or heat
treat the fibers as needed using conventional technique to make
stable and useful fibers. The fibers formed from the polymers
described herein are useful in a variety of applications. They are
colorless, or colorless to white in color, although impurities can
impart discoloration, and are particularly useful as flame
retardant fibers as the polymers have a limiting oxygen index of
about 24 or greater, or about 26 or greater, or about 28 or
greater, or about 30 or greater.
[0067] In one embodiment, fibers can be spun from sulfuric acid
solutions ranging in concentration from 5 to 25 wt % polymer using
a spinneret with 5-50 holes having diameter of 0.003'' or 0.008''.
The volumetric flow rate of spinning solution is typically 0.3-2
mL/min. The fiber is then extruded directly into a coagulation bath
filled with a room temperature or elevated temperature or
sub-ambient temperature solution containing 0-70 wt. % sulfuric
acid, saturated salt solutions, or basic aqueous solutions.
[0068] The number, size, shape, and configuration of the orifices
can be varied to achieve the desired fiber product. The extruded
dope is fed into a coagulation bath with or without prior passage
through a noncoagulating fluid layer. The noncoagulating fluid
layer is generally air but can be any other inert gas or liquid
which is a noncoagulant for the dope.
[0069] The fibers and/or film can contain common additives such as
dyes, pigments, antioxidants, delusterants, antistatic agents, and
U.V. stabilizers, added either to the spin solution, dope or to the
coagulation bath, or coated on the fiber during or after the
spinning process.
[0070] As used herein, the term "staple fibers" refers to fibers
that are cut to a desired length or are stretch broken, or fibers
that occur naturally with or are made having a low ratio of length
to the width of the cross-sectional area perpendicular to that
length when compared with filaments. Man made staple fibers are cut
or made to a length suitable for processing on cotton, woolen, or
worsted yarn spinning equipment. The staple fibers can have (a)
substantially uniform length, (b) variable or random length, or (c)
subsets of the staple fibers have substantially uniform length and
the staple fibers in the other subsets have different lengths, with
the staple fibers in the subsets mixed together forming a
substantially uniform distribution.
[0071] In some embodiments, suitable staple fibers have a length of
about 0.25 centimeters (0.1 inches) to about 30 centimeters (12
inches). In some embodiments, the length of a staple fiber is from
about 1 cm (0.39 in) to about 20 cm (8 in). In some preferred
embodiments the staple fibers made by short staple processes have a
staple fiber length of about 1 cm (0.39 in) to about 6 cm (2.4
in).
[0072] The staple fibers can be made by any process. For example,
the staple fibers can be cut from continuous straight fibers using
a rotary cutter or a guillotine cutter resulting in straight (i.e.,
non crimped) staple fiber, or additionally cut from crimped
continuous fibers having a saw tooth shaped crimp along the length
of the staple fiber, with a crimp (or repeating bend) frequency of
preferably no more than 8 crimps per centimeter.
[0073] The staple fibers can also be formed by stretch breaking
continuous fibers resulting in staple fibers with deformed sections
that act as crimps. Stretch broken staple fibers can be made by
breaking a tow or a bundle of continuous filaments during a stretch
break operation having one or more break zones that are a
prescribed distance creating a random variable mass of fibers
having an average cut length controlled by break zone
adjustment.
[0074] Spun staple yarn can be made from staple fibers using
traditional long and short staple ring spinning processes that are
well known in the art. For short staple, cotton system spinning
fiber lengths from about 1.9 to 5.7 cm (0.75 in to 2.25 in) are
typically used. For long staple, worsted or woolen system spinning,
fibers up to about 16.5 cm (6.5 in) are typically used. However,
this is not intended to be limiting to ring spinning because the
yarns may also be spun using air jet spinning, open end spinning,
and many other types of spinning which converts staple fiber into
useable yarns.
[0075] Spun staple yarns can also be made directly by stretch
breaking using stretch-broken tow to top staple processes. The
staple fibers in the yarns formed by traditional stretch break
processes typically have length of up to about 18 cm (7 in) long.
However spun staple yarns made by stretch breaking can also have
staple fibers having maximum lengths of up to around 50 cm (20 in.)
through processes as described for example in PCT Patent
Application No. WO 0077283. Stretch broken staple fibers normally
do not require crimp because the stretch-breaking process imparts a
degree of crimp into the fiber.
[0076] The staple fibers can also be formed by stretch breaking
continuous fibers resulting in staple fibers with deformed sections
that act as crimps. Stretch broken staple fibers can be made by
breaking a tow or a bundle of continuous filaments during a stretch
break operation having one or more break zones that are a
prescribed distance creating a random variable mass of fibers
having an average cut length controlled by break zone
adjustment.
[0077] The term continuous filament refers to a flexible fiber
having relatively small-diameter and whose length is longer than
those indicated for staple fibers. Continuous filament fibers and
multifilament yarns of continuous filaments can be made by
processes well known to those skilled in the art.
[0078] Many different fibers can be used as the textile staple
fiber. In some embodiments aramid fiber can be used in the blend as
the textile staple fiber. In some preferred embodiments meta-aramid
fibers are used in the blend as the textile staple fiber. By aramid
is meant a polyamide wherein at least 85% of the amide (--CONH--)
linkages are attached directly to two aromatic rings. A meta-aramid
is such a polyamide that contains a meta configuration or
meta-oriented linkages in the polymer chain. Meta-aramid fibers are
currently available under the trademarks Nomex.RTM. from E. I. du
Pont de Nemours of Wilmington, Del. Additives can be used with the
aramid and, in fact it has been found that up to as much as 10
percent, by weight, of other polymeric material can be blended with
the aramid or that copolymers can be used having as much as 10
percent of other diamine substituted for the diamine of the aramid
or as much as 10 percent of other diacid chloride substituted for
the diacid chloride of the aramid. In some embodiments, the
preferred meta-aramid fiber is poly(meta-phenylene isophthalamide)
(MPD-I). This fiber may be spun by dry or wet spinning using any
number of processes; U.S. Pat. Nos. 3,063,966 and 5,667,743 are
illustrative of useful processes.
[0079] In some embodiments para-aramid fibers can be used as the
textile staple fiber in the blend for increased flame strength and
reduced thermal shrinkage. Para-aramid fibers are currently
available under the trademarks Kevlar.RTM. from E. I. du Pont de
Nemours of Wilmington, Del. and Twaron.RTM. from Teijin Ltd. of
Tokyo, Japan. For the purposes herein, Technora.RTM. fiber, which
is available from Teijin Ltd. of Tokyo, Japan, and is made from
copoly(p-phenylene/3,4'diphenyl ester terephthalamide), is
considered a para-aramid fiber.
[0080] In some embodiments polyazole fibers can be used as the
textile fiber in the blend. For example, suitable polyazoles
include polybenzazoles, polypyridazoles, and the like, and can be
homopolymers or copolymers. Additives can be used with the
polyazoles and up to as much as 10 percent, by weight, of other
polymeric material can be blended with the polyazoles. Also
copolymers can be used having as much as 10 percent or more of
other monomer substituted for a monomer of the polyazoles. Suitable
polyazole homopolymers and copolymers can be made by known
procedures, such as those described in U.S. Pat. No. 4,533,693 (to
Wolfe, et al., on Aug. 6, 1985), U.S. Pat. No. 4,703,103 (to Wolfe,
et al., on Oct. 27, 1987), U.S. Pat. No. 5,089,591 (to Gregory, et
al., on Feb. 18, 1992), U.S. Pat. No. 4,772,678 (Sybert, et al., on
Sep. 20, 1988), U.S. Pat. No. 4,847,350 (to Harris, et al., on Aug.
11, 1992), and U.S. Pat. No. 5,276,128 (to Rosenberg, et al., on
Jan. 4, 1994).
[0081] In some embodiments the preferred polybenzazoles are
polybenzimidazoles, polybenxothiazoles, and polybenzoxazoles. If
the polybenzazole is a polybenzimidazole, preferably it is
poly[5,5'-bi-1H-benzimidazole]-2,2'-diyl-1,3-phenylene which is
called PBI. If the polybenzazole is a polybenxothiazole, preferably
it is a polybenxobisthiazole and more preferably it is
poly(benxo[1,2-d:4,5-d']bisthiazole-2,6-diyl-1,4-phene which is
called PBT. If the polybenzazole is a polybenzoxazole, preferably
it is a polybenzobisoxazole and more preferably it is
poly(benzo[1,2-d:4,5-d']bisoxazole-2,6-diyl-1,4-phenylene which is
called PBO. In some embodiments the preferred polypyridazoles are
rigid-rod polypyridobisazoles including poly(pyridobisimidazole),
poly(pyridobisthiazole), and poly(pyridobisoxazole). The preferred
poly(pyridobisoxazole) is
poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d']bisimidazole
which is called PB. Suitable polypyridobisazoles can be made by
known procedures, such as those described in U.S. Pat. No.
5,674,969.
[0082] In some embodiments modacrylic fibers can be used. The
preferred modacrylic fibers used in this invention are copolymers
of acrylonitrile combined with vinylidene chloride. The copolymer
can have, in addition, an antimony oxide or antimony oxides for
improved fire retardancy. Such useful modacrylic fibers include,
but are not limited to, fibers disclosed in U.S. Pat. No. 3,193,602
having 2 weight percent antimony trioxide, fibers disclosed in U.S.
Pat. No. 3,748,302 made with various antimony oxides that are
present in an amount of at least 2 weight percent and preferably
not greater than 8 weight percent, and fibers disclosed in U.S.
Pat. Nos. 5,208,105 & 5,506,042 having 8 to 40 weight percent
of an antimony compound. The preferred modacrylic fiber is
commercially available from Kaneka Corporation, Japan, in various
forms, some containing no antimony oxides while others such as
Protex C are said to contain 10 to 15 weight percent of those
compounds.
[0083] In some preferred embodiments the various types of staple
fibers are present as a staple fiber blend. By fiber blend it is
meant the combination of two or more staple fiber types in any
manner. Preferably the staple fiber blend is an "intimate blend",
meaning the various staple fibers in the blend form a relatively
uniform mixture of the fibers. In some embodiments the two or more
staple fiber types are blended prior to or while the yarn is being
spun so that the various staple fibers are distributed
homogeneously in the staple yarn bundle.
[0084] Fabrics can be made from the spun staple yarns and can
include, but is not limited to, woven or knitted fabrics. General
fabric designs and constructions are well known to those skilled in
the art. By "woven" fabric is meant a fabric usually formed on a
loom by interlacing warp or lengthwise yarns and filling or
crosswise yarns with each other to generate any fabric weave, such
as plain weave, crowfoot weave, basket weave, satin weave, twill
weave, and the like. Plain and twill weaves are believed to be the
most common weaves used in the trade and are preferred in many
embodiments.
[0085] By "knitted" fabric is meant a fabric usually formed by
interlooping yarn loops by the use of needles. In many instances,
to make a knitted fabric spun staple yarn is fed to a knitting
machine which converts the yarn to fabric. If desired, multiple
ends or yarns can be supplied to the knitting machine either plied
of unplied; that is, a bundle of yarns or a bundle of plied yarns
can be co-fed to the knitting machine and knitted into a fabric, or
directly into a article of apparel such as a glove, using
conventional techniques. In some embodiments it is desirable to add
functionality to the knitted fabric by co-feeding one or more other
staple or continuous filament yarns with one or more spun staple
yarns having the intimate blend of fibers. The tightness of the
knit can be adjusted to meet any specific need. A very effective
combination of properties for protective apparel has been found in
for example, single jersey knit and terry knit patterns.
[0086] In some particularly useful embodiments, the spun staple
yarns can be used to make flame-resistant garments. In some
embodiments the garments can have essentially one layer of the
protective fabric made from the spun staple yarn. Exemplary
garments of this type include jumpsuits and coveralls for fire
fighters or for military personnel. Such suits are typically used
over the firefighters clothing and can be used to parachute into an
area to fight a forest fire. Other garments can include pants,
shirts, gloves, sleeves and the like that can be worn in situations
such as chemical processing industries or industrial
electrical/utility where an extreme thermal event might occur. In
some preferred embodiments the fabrics have an arc resistance of at
least 0.8 calories per square centimeter per ounce per square
yard.
[0087] In one embodiment the fiber mixture of the sulfonated
polyoxadiazole based staple fiber and the textile staple fiber is
formed by making an intimate blend of the fibers. If desired, other
staple fibers can be combined in this relatively uniform mixture of
staple fibers. The blending can be achieved by any number of ways
known in the art, including processes that creel a number of
bobbins of continuous filaments and concurrently cut the two or
more types of filaments to form a blend of cut staple fibers; or
processes that involve opening bales of different staple fibers and
then opening and blending the various fibers in openers, blenders,
and cards; or processes that form slivers of various staple fibers
which are then further processed to form a mixture, such as in a
card to form a sliver of a mixture of fibers. Other processes of
making an intimate fiber blend are possible as long as the various
types of different fibers are relatively uniformly distributed
throughout the blend. If yarns are formed from the blend, the yarns
have a relatively uniform mixture of the staple fibers also.
Generally, in most preferred embodiments the individual staple
fibers are opened or separated to a degree that is normal in fiber
processing to make a useful fabric, such that fiber knots or slubs
and other major defects due to poor opening of the staple fibers
are not present in an amount that detract from the final fabric
quality.
[0088] In a preferred process, the intimate staple fiber blend is
made by first mixing together staple fibers obtained from opened
bales, along with any other staple fibers, if desired for
additional functionality. The fiber blend is then formed into a
sliver using a carding machine. A carding machine is commonly used
in the fiber industry to separate, align, and deliver fibers into a
continuous strand of loosely assembled fibers without substantial
twist, commonly known as carded sliver. The carded sliver is
processed into drawn sliver, typically by, but not limited to, a
two-step drawing process.
[0089] Spun staple yarns are then formed from the drawn sliver
using techniques including conventional cotton system or
short-staple spinning processes such as open-end spinning and
ring-spinning; or higher speed air spinning techniques such as
Murata air-jet spinning where air is used to twist the staple
fibers into a yarn. The formation of spun yarns can also be
achieved by use of conventional woolen system or long-staple
processes such as worsted or semi-worsted ring-spinning or
stretch-break spinning. Regardless of the processing system,
ring-spinning is the generally preferred method for making the spun
staple yarns.
EXAMPLES
[0090] Unless otherwise stated, the examples were all prepared
using the following procedures. Ratios of reagents are given as
mole ratios. Oleum, was obtained from E. I. du Pont de Nemours and
Company, Wilmington, Del. Terephthalic acid (TA), isophthalic acid
(IA), 4,4'-oxybis(benzoic acid) (OBBA), methane sulfonic acid,
polyphosphoric acid, and d.sub.6-dimethylsulfoxide were obtained
from Sigma-Aldrich.RTM.. Hydrazine sulfate was obtained from Acros
Organics. Sulfuric acid and sodium bicarbonate were obtained from
EMD Chemicals, Inc.
General Polymerization Procedure
[0091] Unless otherwise specified, the following general
polymerization procedure was used in each example while varying the
ratio of the monomers, as specified. To a dried 100 mL glass
reactor equipped with a glass mechanical stirrer, nitrogen inlet,
and reagent addition ports were added via powder funnel hydrazine
sulfate (0.015 mol, 1 molar equivalent) and the dicarboxylic
acid(s) in amounts that total 1 molar equivalent. The molar ratios
of dicarboxylic acids:hydrazine sulfate were 1:1, unless otherwise
specified. The specific molar ratios of each dicarboxylic acid are
specified in the examples. The solid ingredients were blended
together thoroughly for 15 minutes under nitrogen. To this blended
mixture of solids was added 19.028 g (0.0712 mol SO.sub.3) of 30%
oleum (fuming sulfuric acid, 30% by weight free SO.sub.3 content)
at room temperature while stirring. The reaction kettle was
completely sealed and leak-free (including stirrer shaft) to
prevent vapor phase ingredients from escaping the kettle. The
mixture was mechanically stirred at room temperature for several
minutes. The reactor was then immersed into an oil bath, and heated
to 130.degree. C. The polymerization was allowed to proceed for 4
hours at 130.degree. C. During the polymerization, the stir rate
was often reduced or stopped if the viscosity of the polymerization
solution became too high.
[0092] In some examples, pre-reacted 4,4'-oxybis(benzoic acid
(OBBA) was used. OBBA was dissolved in 30% oleum, and the reaction
was allowed to proceed for 6.5 hours at 130.degree. C. The reactor
was charged with hydrazine sulfate and the other dicarboxylic
acids, in the same ratios as above. The solution of
4,4'-oxybis(benzoic acid) was then added. The mixture contained a
lot of solid chunks which did not incorporate into the reaction
mixture well until approximately 200 minutes had passed at
130.degree. C. The polymerization was allowed to proceed for 4
hours at 130.degree. C.
General Fiber Formation Procedure
[0093] Three methods were used to prepare fibers. Fibers in
Examples 1-19 were prepared by the following. The polymer reaction
mixture was diluted with sulfuric acid (95-98%). Sufficient
sulfuric acid was added so that the solution viscosity was high
enough such that a thin continuous stream could be dropped into a
blender containing water while rotating at a rate, to ensure that
the coagulated fiber not be pulled apart. Optimization of this
process was determined for each polymerization. In order to
coagulate fiber, a rubber septum was added to the top of the
blender blade, which allowed for the fiber to be wound around and
collected. The fiber was then rewound onto a glass vial, typically
by hand, washed with water, and then soaked in dilute sodium
bicarbonate until fully neutralized. The fiber was then washed and
soaked with water to remove any residual sodium bicarbonate. The
fibers were allowed to dry at ambient conditions. In some examples,
a sample of the fiber was dried under high vacuum at room
temperature for molecular weight determination by size exclusion
chromatography (SEC) in methane sulfonic acid.
[0094] Fibers in Examples 20 and 21 were prepared by the following
procedure. The fibers were spun from sulfuric acid solutions that
ranged in concentration from 6-9 wt % polymer. The solution was
delivered by a gear pump through a spinneret with 10 holes having
diameter of 0.005'' or 0.008''. The volumetric flow rate of
spinning solution was 0.3-2 mL/min. The fiber was extruded directly
into a coagulation bath filled with a room temperature solution
that was 0-20 wt. % sulfuric acid. Fiber residence time in the
coagulation bath was between 15 and 60 seconds. The fiber emerged
from the coagulation bath through a ceramic guide into a wash bath
of room temperature water. In the wash bath the fiber was wrapped
around two speed-controlled driven rolls and then drawn 50-100%.
Three wraps were usually made around each of these rolls. The fiber
was wound onto a phenolic core. The wound fiber bobbins were then
neutralized in 0.5 wt % sodium bicarbonate solution, washed in
de-ionized water and air dried at room temperature in a series of
batch steps.
[0095] Fibers were also prepared by the following procedure. The
fibers were spun from sulfuric acid solutions that ranged in
concentration from 4-14 wt % polymer. The solution was delivered by
a gear pump through a spinneret with 10-20 holes having diameter of
0.003'' or 0.008''. The volumetric flow rate of spinning solution
was 0.3-2 mL/min. The fiber was extruded directly above a
coagulation bath filled with a room temperature, elevated
temperature, or sub-ambient temperature solution that was 0-70 wt.
% sulfuric acid. The fiber was 1/8'' to 6 inches from the
coagulation bath. Fiber residence time in the coagulation bath was
between 15 and 60 seconds. The fiber emerged from the coagulation
bath through a ceramic guide into a wash bath of room temperature,
elevated temperature, or sub-ambient temperature water, acid
aqueous, or basic aqueous solution. In the wash bath the fiber was
wrapped around two speed-controlled driven rolls and then drawn
0-500%. Three wraps were usually made around each of these rolls.
The fiber was wound onto a phenolic core. The wound fiber bobbins
were then neutralized in slightly basic solution, washed in
de-ionized water and air dried at room temperature or elevated
temperature or dried in a vacuum oven at room temperature or
elevated temperature in a series of batch steps.
General Cast Film Preparation Procedure
[0096] The polymerization solution was diluted with sulfuric acid
(95-98%) until the viscosity achieved would allow pouring onto a
glass plate to give a uniform film. This viscosity was typically
less than the viscosity required to coagulate fiber. The polymer
and glass plate were immersed into a water bath in order to
coagulate the film. The coagulated film was washed with water and
then soaked in dilute sodium bicarbonate until fully neutralized.
The film was then washed and soaked with water to remove any
residual sodium bicarbonate. The film was pressed under varying
amounts of pressure between paper towels, repeatedly, until mostly
dry by touch. The film was then placed between aluminum foil sheets
and pressed at 10,000 lb for 5 minutes. The resulting film was
dried under high vacuum at room temperature for 24 hours.
General Pulp Film Preparation Procedure
[0097] A cast film as prepared above was pulped into small
particles in a blender with water. The solids were filtered through
a glass fritted filter and washed with water repeatedly. The solid
was pulped in the blender again with dilute sodium bicarbonate
solution until neutralized, filtered through a glass fritted filter
and washed with water repeatedly. The solid was pulped in the
blender again with water, filtered through a glass fritted filter
and washed with water repeatedly. The pulping process was then
repeated. The solid film was dried on the glass fritted filter
until it could be gently removed in one piece. The film was pressed
under varying amounts of pressure between paper towels, repeatedly,
until mostly dry by touch. The film was then placed between
aluminum foil and pressed at 10,000 lb for 30 minutes. The film was
dried under high vacuum at room temperature.
LOI Measurement
[0098] Limiting Oxygen Index (LOI) is the minimum concentration of
oxygen, expressed as a volume percent, in a mixture of oxygen and
nitrogen that will just support the flaming combustion of a
material initially at room temperature under the conditions of ASTM
G125/D2863. LOI was measured using a modified ASTM method (ASTM D
2863) to allow for rapid screening of the samples. Films were
mounted in sample holder which was inserted in the LOI apparatus
and covered with a glass chimney. The oxygen content within the
glass chimney was controlled digitally. The film was exposed to a
flame, and the oxygen level in the chimney was increased until the
sample burns. The LOI of any given sample was measured at the point
at which candle-like burning can be sustained. Sample data and
results are summarized in Table 1.
TABLE-US-00001 TABLE 1 IA TA OBBA M.sub.n M.sub.w Ex. mol % mol %
mol % (g/mol) (g/mol) M.sub.w/M.sub.n LOI 1 10 80 10 6000 17800
2.96 27 Off-white, fairly strong. T.sub.d onset was ~503.degree. C.
2 5 75 20 31000 69100 2.23 30.5 .+-. 0.5 White, strong 3 0 80 20
36600 67300 1.84 30.2 .+-. 0.9 Colorless to white, strong, high
degree of elongation 4 0 50 50 30500 49700 1.63 23.0 .+-. 0.0
White, weak, high degree of elongation 5 0 60 40 30200 57800 1.92
29.0 .+-. 1.0 Colorless to white, fairly strong 6 0 70 30 28900
56600 1.96 31.3 .+-. 1.1 White to colorless, very strong, high
degree of elongation 7 0 95 5 32700 90500 2.77 26.0 .+-. 0.0
Yellow, strong, high degree of elongation 8 0 90 10 31100 77900
2.50 26.7 .+-. 0.5 Yellow, strong, high degree of elongation 9 0 75
25 58100 77300 1.33 31.0 .+-. 1.0 Colorless to white, strong, high
degree of elongation 10.sup.(1) 0 75 25 16100 54800 3.40 25 Films
prepared. No sulfonation 11 0 75 25 24100 47000 1.95 35 Films
prepared 12 0 75 25 26100 59700 2.29 34 Colorless to white, strong,
high degree of elongation 13.sup.(2) 0 75 25 30500 71300 2.34
>33 Films prepared 14.sup.(2) 0 75 25 15500 42000 2.71 34 Films
prepared 15 0 82 18 29800 85500 2.87 29 Colorless to white, fairly
strong, high degree of elongation 16.sup.(2) 0 75 25 13000 38200
2.95 32.2 .+-. 0.3 White fiber was fairly weak 17.sup.(2) 0 75 25
12000 34900 2.92 32 White fiber was fairly weak 18 0 75 25 25600
64200 2.51 31.5 .+-. 0.5 Colorless to white, strong, high degree of
elongation 19.sup.(3) 0 0 100 10900 33800 3.10 -- Polymer was water
soluble 20.sup.(4) 20 80 0 19300 45200 2.34 -- Colorless to white,
strong, high degree of elongation 21.sup.(5) 0 75 25 19300 41100
2.12 35.3 .+-. 0.6 Colorless to white, strong, high degree of
elongation .sup.(1)Comparative example. Oleum was replaced by
polyphosphoric acid and sulfuric acid was replaced by phosphoric
acid .sup.(2)Pre-reacted OBBA was used .sup.(3)Comparative example
.sup.(4)Comparative example performed on larger scale. Polymer was
prepared by mixing 86.885 grams (0.6677 moles hydrazine) of solid
hydrazine sulfate, 105.12 grams (0.6327 moles) of solid
terephthalic acid, and 9.000 grams (0.0333 moles) of solid
isophthalic acid were mixed and blended together in a mixer for 30
min. A first addition of 30% oleum, 534 grams oleum (2.001 moles of
SO.sub.3) was added at 25.degree. C., mechanically stirred at
25.degree. C. for 15 minutes, then heated to 120.degree. C. with
mechanical stirring until a constant torque was observed on the
mixer (60 minutes). A second addition of 30% oleum, 611 grams oleum
(2.290 moles of SO.sub.3) was then added at 130.degree. C. The
temperature was maintained at 130.degree. C. for 2 hours until the
viscosity of the solution reached a plateau, then cooled to room
temperature. .sup.(5)Example performed on larger scale (2 L) using
hydrazine sulfate (1.005 molar equivalents), terephthalic acid,
4,4'-oxybis(benzoic acid), and 20% oleum. The resulting extremely
viscous amber mixture was quenched and diluted to 9.42 wt % by the
addition of water.
Example 22
Proof of Sulfonation of 4,4'-oxybis(benzoic acid)
[0099] 4,4'-Oxybis(benzoic acid) (87 mg, Aldrich 99%) were added to
0.9 mL of 30% oleum. The material was stirred for <1 minutes at
ambient temperature and transferred immediately to a 5 mm outer
diameter (o.d) tube suitable for nuclear magnetic resonance (NMR)
spectroscopic studies. Into the NMR tube had previously been
inserted a sealed capillary containing dimethyl sulfoxide-d.sub.6
for deuterium lock and chemical shift referencing. The tube was
immediately inserted into a NMR probe held at 30.degree. C. After a
brief period to homogenize ("shim") the magnetic field, an
automated series of .sup.1H NMR spectra were acquired on the
sample.
[0100] Resonances at 8.11 and 6.98 ppm were assigned to .sup.1H
nuclei of unsulfonated rings, and resonances at 8.47, 8.18, and
7.06 ppm were assigned to those of sulfonated rings substituted at
the position ortho to the ether linkage. During the course of the
kinetic spectral acquisition, the resonances assigned to
unsulfonated rings diminished in intensity, and those assigned to
sulfonated rings increased, indicating sulfonation of the rings.
The half-life of this process at 30.degree. C. was 52 min.
Example 23
Proof of Structure of Sulfonylated 4,4'-oxybis(benzoic acid)
[0101] A 40 mL vial containing a magnetic stir bar was charged with
4,4'-oxybis(benzoic acid) (6.0 g) and 30% oleum (39.6 g). The
mixture was heated in a 130.degree. C. hot block for 3 days.
Samples (1 mL) of the resulting clear brown solution were then
quenched with water and vortexed to mix. The precipitated solids
were filtered and sparingly washed with ice water. The remaining
solid was predominately the monosulfonated sulfone product and the
aqueous filtrate predominately contained the disulfonated sulfone.
.sup.1H NMR spectrum and LC/MS were performed and indicate that the
desired sulfonated and sulfonylated products were formed.
[0102] A saturated solution of the monosulfonated sulfone product
was prepared in water-d.sub.2 containing a trace of sodium
3-trimethylsilylpropionate-d.sub.4 as a chemical shift referent.
The solution was inserted in a NMR probe and heated to 60.degree.
C. to ensure dissolution. A series of NMR two dimensional
correlation experiments were performed to elucidate the structure
of the material. These experiments permitted assignment of the
.sup.1H resonances of the primary product,
4-sulfophenoxathiine-2,8-dicarboxylic acid 10,10-dioxide. The
.sup.1H assignments (in ppm relative to chemical shift referent at
0.00 ppm) are shown in the following below.
##STR00005##
Example 24
Proof of Sulfonylation and Sulfonation of Polymers
[0103] Poly(phenylene-co-4,4'-oxybis(benzoic acid)disulfonate
oxadiazole) (34.4 mg), in which the terephthalic acid and
4,4'-oxybis(benzoic acid) monomer units were present in a 70:30
molar ratio, were dissolved in 30% oleum (1.384 g) at 50.degree. C.
This material was transferred into a cylindrical tube with 3 mm
o.d., suitable for use in NMR spectroscopy. This tube was then
frozen in liquid nitrogen, evacuated, and flame-sealed. The sealed
tube was inserted in a 5 mm o.d. NMR tube, with the interstitial
space between the tubes filled with dimethylsulfoxide-d.sub.6. The
tubes were then inserted in a NMR probe and heated to 130.degree.
C. Upon reaching temperature, an automated series of .sup.1H NMR
spectral acquisitions was initiated, using quantitative acquisition
conditions so as to study the kinetics of reaction. Sulfonylation
of the 4,4'-oxybis(benzoic acid) rings was observed, as discussed
in previous examples.
[0104] The material formed in Example 9 was analyzed via NMR, and
using the spectral assignments from above, it was found that 17.65%
of the OBBA monomer was in the disulfonated form, 7.35% was in the
monosulfonated sulfone form, and a trace amount was in the
disulfonated sulfone, which is 5.34 weight % of S:
##STR00006##
[0105] Elemental analysis was performed on the material from
Example 6 and found 43.26% C, 3.07% H, 30.06% O, 10.18% N and 6.50%
S.
Example 25
Synthesis of poly(oxadiazole) (POD) Containing 80:10:10
terephthalic acid:4,4'-oxybis(benzoic acid): 5-sulfoisophthalic
acid
[0106] To a dried 100 mL glass reactor equipped with a glass
mechanical stirrer, nitrogen inlet, and reagent addition ports were
added via powder funnel hydrazine sulfate (0.015 mol, 1.007 molar
equivalents) and the dicarboxylic acids (terephthalic acid (1.994
g, 0.8 molar equivalents), 4,4'-oxybis(benzoic acid) (0.387 g, 0.1
molar equivalents), and 5-sulfoisophthalic acid (0.402 g, 0.1 molar
equivalents)) in amounts that total 1 molar equivalent. The solid
ingredients were blended together thoroughly for 15 minutes under
nitrogen. To this blended mixture of solids was added 28.5 g of 20%
oleum (fuming sulfuric acid, 20% by weight free SO.sub.3 content)
at room temperature while stirring. The reaction kettle was
completely sealed and leak-free (including stirrer shaft) to
prevent vapor phase ingredients from escaping the kettle. The
mixture was mechanically stirred at room temperature for several
minutes. The reactor was then immersed into an oil bath, and heated
to 130.degree. C. The polymerization was allowed to proceed for 4
hours at 130.degree. C. During the polymerization, the stir rate
was often reduced or stopped if the viscosity of the polymerization
solution became too high.
Example 26
25% OBBA-POD Fiber Dyed in Red Dye #29 with Benzyl Alcohol
Carrier
[0107] To a round bottom flask containing a magnetic stir bar and
fiber (0.037 g) was added a solution (82 g) consisting of 10 wt %
MERPOL HCS (Aldrich, 1.25 g), TSPP (Aldrich, sodium pyrophosphate
tetrabasic, 0.25 g) and DI water (248.50 g). The mixture was placed
into a 29.degree. C. oil bath and heated at approximately 3.degree.
C./min to 85.degree. C. then held at that temperature for 20 min.
The fiber was washed with hot water and with room temperature
water. The wet fiber was returned to a round bottom flask
containing a magnetic stir bar. To the flask was added a solution
0.1 wt % MERPOL HCS (0.005 g) and a solution (55.00 g) containing
benzyl alcohol (Aldrich, 3.75 g) and DI water (121.25 g). The
mixture was heated in a 46.degree. C. bath for 15 min. Next, Red
Dye #29 (Aldrich, 0.0032 g, 7.96 wt % dye to fiber) was dissolved
into 10.00 g of a solution containing benzyl alcohol (3.75 g) and
DI water (121.25 g) and added to the reaction mixture. The mixture
was heated in the 46.degree. C. for an additional 10 min, the red
solution had become slightly pink and the fiber was deep red. The
mixture was removed from the heated bath and the pH was 6.3. The pH
was adjusted to 3.9 by the addition of acetic acid (1 drop of 0.85
wt %). The mixture was then heated in a 74.degree. C. bath for 15
min and the dye solution had become colorless. The mixture was
heated at reflux in a 130.degree. C. bath for an additional 60 min.
The fiber was washed with hot water and again with room temperature
water. The wet fiber was returned to a round bottom flask
containing a magnetic stir bar. To the flask was added 0.1 wt %
MERPOL HCS (0.04 g) and DI water (50.00 g). The mixture was heated
at 85.degree. C. for an 20 min. The fiber was washed with hot water
and again with room temperature water. It was blotted dry in a
paper towel then placed into an 82.degree. C. oven for 3 h.
Cross-sectional optical microscopy was utilized to ensure complete
dye uptake.
Example 27
[0108] This example illustrates flame-resistant spun yarns and
fabrics of intimate blends of the OBBA-POD fiber from Example 24
and a textile staple fiber having limiting oxygen index of 21 or
greater and a tenacity of about 4 grams per denier or greater, such
as poly(meta-phenylene isophthalamide) (MPD-I) fiber available from
E. I. duPont de Nemours & Company under the trademark
Nomex.RTM. fiber.
[0109] A picker blend sliver of 50 weight percent of OBBA-POD
staple fiber and 50 weight percent of MPD-I staple fiber is
prepared and processed by conventional cotton system equipment and
spun into a flame resistant spun staple yarn having a twist
multiplier of about 4.0 and a single yarn size of about 21 tex (28
cotton count) using a ring spinning frame. Two such single yarns
are then plied on a plying machine to make a two-ply flame
resistant yarn for use as a fabric warp yarn. Using the same blend
and a similar process, including the same twist and blend ratio, a
24 tex (24 cotton count) singles yarn is made, and two of these
single yarns are plied to form a two-ply flame resistant yarn for
use as a fabric fill yarn. Both of these two-ply warp and two-ply
fill yarns have a tenacity greater than the tenacity of a two-ply
100% OBBA-POD staple fiber yarn made under similar conditions,
i.e., the two-ply yarns have a tenacity of at least 3 grams per
denier (2.7 grams per dtex).
[0110] The ring-spun warp and fill yarns are woven into a fabric on
a shuttle loom, making a greige fabric having a 2.times.1 twill
weave and a construction of 26 ends.times.17 picks per cm (72
ends.times.52 picks per inch), and a basis weight of about 215
g/m.sup.2 (6.5 oz/yd.sup.2). The greige twill fabric is then
scoured in hot water and is dried under low tension. The scoured
fabric is then jet dyed using basic dye. The resulting fabric has a
basis weight of about 231 g/m.sup.2 (7 oz/yd.sup.2) and an LOI in
excess of 28.
[0111] A portion of the fabric is cut into various shapes and the
shapes are sewn together to convert the fabric into single-layer
protective garments useful for those exposed to thermal
hazards.
[0112] In a similar manner, ring-spun yarns, and associated fabric
and garment are made from 100% OBBA-POD staple fiber as a
control.
[0113] Table 2 illustrates the properties of the resulting fabric
and garments. A "+" indicates superior properties to those of the
control, while the notation "0" indicates the performance of the
control or performance equivalent to the control.
TABLE-US-00002 TABLE 2 100% Property OBBA-POD Example 27 Grab Test
0 + Break Strength (lbf) W/F Trap Tear 0 + (lbf) W/F Taber Abrasion
0 + (Cycles) CS-10/1000 g TPP 0 0 (cal/cm.sup.2) Vertical Flame 0 0
(in) W/F Instrumented Thermal 0 - Manikin Test (% of body 0 - burn)
ARC rating (cal/cm.sup.2)
Example 28
[0114] This example illustrates flame-resistant spun yarns and
fabrics of intimate blends of the OBBA-POD fiber from Example 24
and a modacrylic fiber, such as modacrylic fiber made by Kaneka
Corporation under the trademark of Protex C.RTM..
[0115] A picker blend sliver of 65 weight percent of OBBA-POD
staple fiber and 35 weight percent of modacrylic staple fiber is
prepared and processed by the conventional cotton system equipment
and spun into a flame resistant spun staple yarn having a twist
multiplier of about 4.0 and a single yarn size of about 21 tex (28
cotton count) using a ring spinning frame. Two such single yarns
are then plied on a plying machine to make a two-ply flame
resistant yarn for use as a fabric warp yarn. Using the same blend
and a similar process, and the same twist and blend ratio, a 24 tex
(24 cotton count) singles yarn is made, and two of these single
yarns are plied to form a two-ply flame resistant yarn for use as a
fabric fill yarn. Both of these two-ply warp and two-ply fill yarns
have a tenacity greater than the tenacity of a two-ply 100%
OBBA-POD staple fiber yarn made under similar conditions, i.e., the
two-ply yarns have a tenacity of at least 3 grams per denier (2.7
grams per dtex).
[0116] The ring-spun warp and fill yarns are woven into a fabric on
a shuttle loom, making a greige fabric having a 2.times.1 twill
weave and a construction of 26 ends.times.17 picks per cm (72
ends.times.52 picks per inch), and a basis weight of about 215
g/m.sup.2 (6.5 oz/yd.sup.2). The greige twill fabric is then
scoured in hot water and is dried under low tension. The scoured
fabric is then jet dyed using basic dye. The resulting fabric has a
basis weight of about 231 g/m.sup.2 (7 oz/yd.sup.2) and an LOI in
excess of 28.
[0117] A portion of the fabric is cut into various shapes and the
shapes are sewn together to convert the fabric into single-layer
protective garments useful for those exposed to thermal
hazards.
[0118] In a similar manner, ring-spun yarns, and associated fabric
and garment are made from 100% OBBA-POD staple fiber as a
control.
[0119] Table 3 illustrates the properties of the resulting fabric
and garments. A "+" indicates superior properties to those of the
control, while the notation "0" indicates the performance of the
control or performance equivalent to the control.
TABLE-US-00003 TABLE 3 100% Property OBBA-POD Example 28 Grab Test
0 + Break Strength (lbf) W/F Trap Tear 0 + (lbf) W/F Taber Abrasion
0 - (Cycles) CS-10/1000 g TPP 0 0 (cal/cm.sup.2) Vertical Flame 0 0
(in) W/F Instrumented Thermal 0 - Manikin Test (% of body 0 + burn)
ARC rating (cal/cm.sup.2)
Example 29
[0120] This example illustrates flame-resistant spun yarns and
fabrics of intimate blends of the OBBA-POD fiber from Example 24
and a fiber having high modulus, specifically a tensile modulus of
200 grams per denier or greater, such as poly(paraphenylene
terephthalamide) (PPD-T) fiber available from E. I. duPont de
Nemours & Company under the trademark Kevlar.RTM. fiber. PPD-T
is known in the art as a rigid-rod polymer.
[0121] A picker blend sliver of 85 weight percent of the OBBA-POD
staple fiber and 15 weight percent of PPD-T staple fiber is
prepared and processed by conventional cotton system equipment and
spun into a flame resistant spun staple yarn having a twist
multiplier of about 4.0 and a single yarn size of about 21 tex (28
cotton count) using a ring spinning frame. Two such single yarns
are then plied on a plying machine to make a two-ply flame
resistant yarn for use as a fabric warp yarn Using the same blend
and a similar process, including the same twist and blend ratio, a
24 tex (24 cotton count) singles yarn is made, and two of these
single yarns are plied to form a two-ply flame resistant yarn for
use as a fabric fill yarn. Both of these two-ply warp and two-ply
fill yarns have a tenacity greater than the tenacity of a two-ply
100% OBBA-POD staple fiber yarn made under similar conditions,
i.e., the two-ply yarns have a tenacity of at least 3 grams per
denier (2.7 grams per dtex).
[0122] The ring-spun warp and fill yarns are woven into a fabric on
a shuttle loom, making a greige fabric having a 2.times.1 twill
weave and a construction of 26 ends.times.17 picks per cm (72
ends.times.52 picks per inch), and a basis weight of about 215
g/m.sup.2 (6.5 oz/yd.sup.2). The greige twill fabric is then
scoured in hot water and is dried under low tension. The scoured
fabric is then jet dyed using basic dye. The resulting fabric has a
basis weight of about 231 g/m.sup.2 (7 oz/yd.sup.2) and an LOI in
excess of 28.
[0123] A portion of the fabric is cut into various shapes and the
shapes are sewn together to convert the fabric into single-layer
protective garments useful for those exposed to thermal
hazards.
[0124] In a similar manner, ring-spun yarns, and associated fabric
and garment are made from 100% OBBA-POD staple fiber as a
control.
[0125] Table 4 illustrates the properties of the resulting fabric
and garments. A "+" indicates superior properties to those of the
control, while the notation "0" indicates the performance of the
control or performance equivalent to the control.
TABLE-US-00004 TABLE 4 100% Property OBBA-POD Example 29 Grab Test
0 - Break Strength (lbf) W/F Trap Tear 0 + (lbf) W/F Taber Abrasion
0 + (Cycles) CS-10/1000 g TPP 0 0 (cal/cm.sup.2) Vertical Flame 0 +
(in) W/F Instrumented Thermal 0 0 Manikin Test (% of body 0 0 burn)
ARC rating (cal/cm.sup.2)
Example 30
[0126] Example 29 is repeated, except the picker blend sliver
contains 40 weight percent of the OBBA-POD staple fiber and 60
weight percent of the PPD-T staple fiber. As in Example 29,
ring-spun yarns, and associated fabric and garment are made from
100% OBBA-POD staple fiber as a control.
[0127] Table 5 illustrates the properties of the resulting fabric
and garments. A "+" indicates superior properties to those of the
control, while the notation "0" indicates the performance of the
control or performance equivalent to the control.
TABLE-US-00005 TABLE 5 100% Property OBBA-POD Example 30 Grab Test
0 + Break Strength (lbf) W/F Trap Tear 0 + (lbf) W/F Taber Abrasion
0 + (Cycles) CS-10/1000 g TPP 0 0 (cal/cm.sup.2) Vertical Flame 0 +
(in) W/F Instrumented Thermal 0 0 Manikin Test (% of body 0 0 burn)
ARC rating (cal/cm.sup.2)
* * * * *