U.S. patent application number 10/630102 was filed with the patent office on 2005-02-03 for flame retardant fiber blends comprising flame retardant cellulosic fibers and fabrics and garments made therefrom.
Invention is credited to Guckert, Debbie, Lovasic, Susan L., Parry, Roger, Zhu, Reiyao.
Application Number | 20050025962 10/630102 |
Document ID | / |
Family ID | 34103770 |
Filed Date | 2005-02-03 |
United States Patent
Application |
20050025962 |
Kind Code |
A1 |
Zhu, Reiyao ; et
al. |
February 3, 2005 |
Flame retardant fiber blends comprising flame retardant cellulosic
fibers and fabrics and garments made therefrom
Abstract
An intimate blend of staple fibers has from 10 to 75 parts by
weight of at least one aramid staple fiber, from 15 to 80 parts by
weight of at least one flame retardant cellulosic staple fiber, and
from 5 to 30 parts by weight of at least one polyamide staple
fiber. The intimate blend of staple fibers provides yarns and
fabrics that are flame retardant, also referred to as fire
resistant, and can be used to make flame retardant articles, such
as clothing. The flame retardant fabrics may have a basis weight
from 4 to 15 ounces per square yard.
Inventors: |
Zhu, Reiyao; (Midlothian,
VA) ; Guckert, Debbie; (Chester, VA) ;
Lovasic, Susan L.; (Chester, VA) ; Parry, Roger;
(Moseley, VA) |
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: |
34103770 |
Appl. No.: |
10/630102 |
Filed: |
July 28, 2003 |
Current U.S.
Class: |
428/359 ;
428/365; 442/189; 442/301 |
Current CPC
Class: |
D04H 1/4334 20130101;
D03D 15/513 20210101; D04H 1/43828 20200501; D10B 2331/021
20130101; D02G 3/443 20130101; D10B 2201/00 20130101; Y10T 442/3065
20150401; Y10T 428/2904 20150115; D04H 1/4342 20130101; D10B
2331/02 20130101; Y10T 442/3976 20150401; D04H 1/43835 20200501;
D04H 1/425 20130101; Y10T 428/2915 20150115; D02G 3/047
20130101 |
Class at
Publication: |
428/359 ;
442/189; 442/301; 428/365 |
International
Class: |
D03D 025/00; D04H
001/00; D03D 015/00 |
Claims
What is claimed is:
1. An intimate blend of staple fibers, comprising: 10 to 75 parts
by weight of at least one aramid staple fiber, 15 to 80 parts by
weight of at least one flame retardant cellulosic staple fiber, and
5 to 30 parts by weight of at least one polyamide staple fiber.
2. The intimate blend of claim 1, wherein there are 20 to 40 parts
by weight of the at least one aramid staple fiber, 50 to 80 parts
by weight of the at least one flame retardant cellulosic staple
fiber, and 15 to 20 parts by weight of the at least one polyamide
staple fiber.
3. The intimate blend of claim 1, wherein the at least one aramid
staple fiber is selected from the group consisting of para-aramid
fibers, meta-aramid fibers, and mixtures thereof.
4. The intimate blend of claim 2, wherein the at least one aramid
staple fiber is selected from the group consisting of para-aramid
fibers, meta-aramid fibers, and mixtures thereof.
5. The intimate blend of claim 1, wherein the at least one aramid
staple fiber is poly(metaphenylene isophthalamide) and the at least
one flame retardant cellulosic staple fiber is flame retardant
rayon.
6. The intimate blend of claim 2, wherein the at least one aramid
staple fiber is poly(metaphenylene isophthalamide) and the at least
one flame retardant cellulosic staple fiber is flame retardant
rayon.
7. The intimate blend of claim 1, wherein the at least one aramid
staple fiber is poly(metaphenylene isophthalamide) and the at least
one flame retardant cellulosic staple fiber comprises silicon
dioxide in the form of polysilicic acid in a cellulose supporting
structure and the silicon dioxide in the form of polysilicic acid
in a cellulose supporting structure is present in an amount of no
more than 40 percent by weight of the intimate blend.
8. The intimate blend of claim 2, wherein the at least one aramid
staple fiber is poly(metaphenylene isophthalamide) and the at least
one flame retardant cellulosic staple fiber comprises silicon
dioxide in the form of polysilicic acid in a cellulose supporting
structure and the silicon dioxide in the form of polysilicic acid
in a cellulose supporting structure is present in an amount of no
more than 40 percent by weight of the intimate blend.
9. A yarn comprising the intimate blend of claim 1.
10. A flame retardant fabric comprising the yarn of claim 9.
11. The flame retardant fabric of claim 10, wherein the flame
retardant fabric has a basis weight of from 4 to 15 ounces per
square yard.
12. A flame retardant article of clothing comprising the flame
retardant fabric of claim 11.
13. The flame retardant fabric of claim 10, wherein the flame
retardant fabric has a basis weight of from 5.5 to 11 ounces per
square yard.
14. A flame retardant article of clothing comprising the flame
retardant fabric of claim 13.
15. A yarn comprising the intimate blend of claim 5.
16. A flame retardant fabric comprising the yarn of claim 15.
17. The flame retardant fabric of claim 16, wherein the flame
retardant fabric has a basis weight of from 4 to 15 ounces per
square yard.
18. A flame retardant article of clothing comprising the flame
retardant fabric of claim 17.
19. The flame retardant fabric of claim 16, wherein the flame
retardant fabric has a basis weight of from 5.5 to 11 ounces per
square yard.
20. A flame retardant article of clothing comprising the flame
retardant fabric of claim 19.
Description
BACKGROUND OF THE INVENTION
[0001] There is an ongoing need for flame retardant, also referred
to as fire resistant, fabrics that can be used to make clothing
suitable for people who work near flames, high temperatures, or
electric arc flashes. In addition to showing excellent thermal
performance, an effective flame retardant fabric should be durable,
comfortable, and produced at low cost. Although fabrics made of
inherently flame retardant fibers have been very useful in
protective garments, certain characteristics of these fibers
present problems. For instance, these fibers can be difficult to
dye, provide uncomfortable fabric textures, and are expensive. To
address these problems, inherently flame retardant fibers have been
blended with fibers made of other materials. Fiber blending can be
used to obtain an end fabric that combines the beneficial
characteristics of each of the constituent fibers. However, such
blending often comes at the expense of durability and thermal
performance.
[0002] Certain fiber blends and fabrics made from those blends are
known in the art. For instance, U.S. Pat. No. 4,920,000 (Green)
issued on Apr. 24, 1990 discloses a durable heat resistant fabric
comprising certain blends of cotton, nylon, and heat resistant
fibers. U.S. Pat. No. 6,132,476 (Lunsford et al.) issued Oct. 17,
2000 discloses dyed fabric blends containing inherently flame
retardant fibers and flame retardant cellulosic fibers containing a
flame retardant compound. U.S. Pat. No. 6,254,988 B1 (Zhu et al.)
issued on Jul. 3, 2001 discloses a fabric composed of particular
blends of cotton, nylon, and para-aramid fibers that is
comfortable, cut resistant, and abrasion resistant. U.S. Patent
Application Publication No. 2001/0009832 A1 (Shaffer et al.)
published on Jul. 26, 2001 discloses a flame retardant fabric
comprising dissimilar warp and fill yarns wherein the warp yarns
comprise staple or filament fibers and have a Limiting Oxygen Index
of at least 27, the fill yarns comprise natural fibers, and the
ratio of warp to fill yarn ends in the fabric is at least 1.0. U.S.
Pat. No. 6,547,835 B1 (Lunsford et al.) issued on Apr. 15, 2003
discloses a method for dyeing flame retardant fabrics.
[0003] Fabrics made from the fiber blends and yarns discussed above
either naturally suffer from poor resistance to abrasion or, as
disclosed in U.S. Pat. No. 4,920,000 (Green) issued on Apr. 24,
1990, utilize a large percentage of cotton fiber, which has very
low abrasion resistance. Fire protective clothing and garments are
normally used in harsh environments so any improvement in abrasion
resistance of the fabrics used in those garments is important and
desired. There is therefore, a need for flame retardant fiber
blends, yarns, and fabrics that have improved abrasion
resistance.
SUMMARY OF THE INVENTION
[0004] In accordance with the purpose of the invention, as embodied
and broadly described herein, the invention is an intimate blend of
staple fibers comprising 10 to 75 parts by weight of at least one
aramid staple fiber, 15 to 80 parts by weight of at least one flame
retardant cellulosic staple fiber, and 5 to 30 parts by weight of
at least one polyamide staple fiber.
[0005] In another embodiment, the invention is an intimate blend of
staple fibers comprising 20 to 40 parts by weight of at least one
aramid staple fiber, 50 to 80 parts by weight of at least one flame
retardant cellulosic staple fiber, and 15 to 20 parts by weight of
at least one polyamide staple fiber.
[0006] In another embodiment, the invention is one of the intimate
blends described above, wherein the at least one aramid staple
fiber is poly(metaphenylene isophthalamide) and the at least one
flame retardant cellulosic staple fiber is flame retardant
rayon.
[0007] In another embodiment, the invention is one of the intimate
blends described above, wherein the at least one aramid staple
fiber is poly(metaphenylene isophthalamide) and the at least one
flame retardant cellulosic staple fiber comprises silicon dioxide
in the form of polysilicic acid in a cellulose supporting structure
and the silicon dioxide in the form of polysilicic acid in a
cellulose supporting structure is present in an amount of no more
than 40 percent by weight of the intimate blend.
[0008] The intimate blends of this invention may be used to make a
yarn, which in turn may be used to make a flame retardant fabric
for use in flame retardant articles such as clothing.
[0009] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating embodiments of the invention,
are given by way of illustration only, because various changes and
modifications within the spirit and scope of the invention will
become apparent to those skilled in the art from this detailed
description. It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
DETAILED DESCRIPTION
[0010] There is an ongoing need for fiber blends from which flame
retardant, also referred to as fire resistant, fabrics can be made
that can be used to make clothing and other articles suitable for
people who work near flames, high temperatures, or electric arc
flashes and the like. Considerable effort has been made to increase
the effectiveness of such fiber blends and the resulting fabrics,
while maintaining or improving their comfort and durability and
reducing their overall cost. The present invention represents just
such an advance in the field of flame retardant garments.
[0011] An intimate blend of staple fibers of this invention
comprises aramid fibers, flame retardant cellulosic fibers, and
polyamide fibers. The proportions of each component are important
to achieve the necessary combination of physical qualities. By
"intimate blend" is meant that two or more fiber classes are
blended prior to spinning a yarn. In the present invention, the
intimate blend is formed by combining aramid fibers, flame
retardant cellulosic fibers, and polyamide fibers in the fiber
form, and then spinning into a single strand of yarn. By "yarn" is
meant an assemblage of fibers spun or twisted together to form a
continuous strand, which can be used in weaving, knitting,
braiding, or plaiting, or otherwise made into a textile material or
fabric. Such yarns can be made by conventional methods for spinning
staple fibers into yarns, such as, for example, ring-spinning, or
higher speed air spinning techniques such as Murata air-jet
spinning where air is used to twist the staple into a yarn.
[0012] The intimate blend of staple fibers of this invention
includes aramid fibers, which are inherently flame retardant. By
"aramid fiber" is meant one or more fibers made from one or more
aromatic polyamides, wherein at least 85% of the amide (--CONH--)
linkages are attached directly to two aromatic rings. Aromatic
polyamides are formed by reactions of aromatic diacid chlorides
with aromatic diamines to produce amide linkages in an amide
solvent. Aramid fibers may be spun by dry or wet spinning using any
number of processes, however, U.S. Pat. Nos. 3,063,966; 3,227,793;
3,287,324; 3,414,645; 3,869,430; 3,869,429; 3,767,756; and
5,667,743 are illustrative of useful spinning processes for making
fibers that could be used in this invention.
[0013] Aramid fibers are typically available in two distinct
classes, namely meta-aramid fibers, or m-aramid fibers, one of
which is composed of poly(metaphenylene isophthalamide), which is
also referred to as MPD-I, and para-aramid fibers, or p-aramid
fibers, one of which is composed of poly(paraphenylene
terephthalamide), also referred to as PPD-T. Meta-aramid fibers are
currently available from E.I. DuPont de Nemours of Wilmington, Del.
in several forms under the trademark NOMEX.RTM.: NOMEX T-450.RTM.
is 100% meta-aramid; NOMEX T-455.RTM. is a blend of 95% NOMEX.RTM.
and 5% KEVLAR.RTM. (para-aramid); and NOMEX IIIA.RTM. (also known
as NOMEX T462.RTM.) is 93% NOMEX.RTM., 5% KEVLAR.RTM., and 2%
carbon core nylon. In addition, meta-aramid fibers are available
under the trademarks CONEX.RTM. and APYEIL.RTM. which are produced
by Teijin, Ltd. of Tokyo, Japan and Unitika, Ltd. of Osaka, Japan,
respectively. Para-aramid fibers are currently available under the
trademarks KEVLAR.RTM. from E.I. DuPont 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.
[0014] In one embodiment of this invention, the at least one aramid
staple fiber is poly(metaphenylene isophthalamide).
[0015] The intimate blend of staple fibers of this invention also
includes flame retardant cellulosic fibers. Flame retardant
cellulosic staple fibers are comprised of one or more cellulosic
fibers and one or more flame retardant compounds. Cellulosic
fibers, such as rayon, acetate, triacetate, and lyocell, which are
generic terms for fibers derived from cellulose, are well-known in
the art.
[0016] Cellulosic fibers, although softer and less expensive than
inherently flame retardant fibers, are not naturally resistant to
flames. To increase the flame retarding capability of these fibers,
one or more flame retardants are incorporated into or with the
cellulosic fibers. Such flame retardants can be incorporated by
spinning the flame retardant into the cellulosic fiber, coating the
cellulosic fiber with the flame retardant, contacting the
cellulosic fiber with the flame retardant and allowing the
cellulosic fiber to absorb the flame retardant, or any other
process that incorporates a flame retardant into or with a
cellulosic fiber. There are a variety of such flame retardants,
including, for example, certain phosphorus compounds, like
SANDOLAST 9000.RTM., currently available from Sandoz, certain
antimony compounds, and the like. Generally speaking, cellulosic
fibers which contain one or more flame retardants are given the
designation "FR," for flame retardant. Accordingly, flame retardant
cellulosic fibers such as FR rayon, FR acetate, FR triacetate, and
FR lyocell may be used in the present invention. Flame retardant
cellulosic fibers are also available under various trademarks, such
as VISIL.RTM., which is available from Sateri Oy of Finland.
VISIL.RTM. fiber contains silicon dioxide in the form of
polysilicic acid in a cellulose supporting structure wherein the
polysilicic acid contains aluminum silicate sites. When the
intimate blends of this invention comprise VISIL.RTM. fibers, the
VISIL.RTM. fibers should be present in an amount of no more than 40
percent by weight of the intimate blend. Methods for making flame
retardant cellulosic fibers are generally disclosed in, for
example, U.S. Pat. No. 5,417,752.
[0017] In one embodiment of this invention, the at least one flame
retardant cellulosic fiber is flame retardant rayon. Rayon is
well-known in the art, and is a generic term for filaments made
from various solutions of modified cellulose by pressing or drawing
the cellulose solution. The cellulose base for the manufacture of
rayon is obtained from wood pulp.
[0018] In another embodiment of this invention the at least one
flame retardant cellulosic staple fiber comprises silicon dioxide
in the form of polysilicic acid in a cellulose supporting structure
and the silicon dioxide in the form of polysilicic acid in a
cellulose supporting structure is present in an amount of no more
than 40 percent by weight of the intimate blend.
[0019] The intimate blend of staple fibers of this invention also
includes polyamide fibers. By "polyamide fibers" is meant one or
more fibers made from one or more aliphatic polyamide polymers,
generically referred to as nylon. Examples include
polyhexamethylene adipamide (nylon 66), polycaprolactam (nylon 6),
polybutyrolactam (nylon 4), poly(9-aminononanoic acid) (nylon 9),
polyenantholactam (nylon 7), polycapryllactam (nylon 8), and
polyhexamethylene sebacamide (nylon 6, 10). Nylon fibers are
generally spun by extrusion of a melt of the polymer through a
capillary into a gaseous congealing medium. When nylon is the
polyamide fiber in the intimate blend of staple fibers forming a
yarn, such yarn preferably is used as the warp yarn when forming a
fabric to enhance protection against soft surface abrasion in the
finished fabric or garment made from such fabric. In one embodiment
of this invention, when nylon is used in this manner to make the
fabrics or garments of this invention, the fabrics or garments of
this invention are expected to have more than ten percent higher
resistance to abrasion compared to similar fabrics without nylon,
as measured in cycles to failure according to the Abrasion
Resistance Test described below. However, too much nylon in a
fabric will cause the fabric to become stiff and lose drape when
the fabric is exposed briefly to high temperatures.
[0020] In one embodiment of this invention, nylon fiber has a
linear density from 1 to 3 dtex. In another embodiment the nylon
fiber has a linear density from 1 to 1.5 dtex. In yet another
embodiment the nylon fiber has a linear density of about 1.1
dtex.
[0021] The intimate blend of staple fibers of this invention can be
used to make yarns and fabrics that are flame retardant. These
yarns and fabrics can be used to make flame retardant articles,
such as flame retardant garments and clothing, which are
particularly useful for firefighters and other workers who are put
in close proximity to flames, high temperatures, or electric arc
flashes. Generally, by "flame retardant" is meant that the fabric
does not support flame in air after coming in contact with a flame
for a short period of time. More precisely, "flame retardant" can
be defined in terms of the Vertical Flame Test, described below.
Flame retardant fabrics preferably have a char length of less than
six inches after a twelve second exposure to a flame. The terms
"flame retardant," "flame resistant," "fire retardant," and "fire
resistant" are used interchangeably in the industry, and references
to "flame retardant" compounds, fibers, yarns, fabric, and garments
in the present invention could be described identically as "flame
resistant," "fire retardant," or "fire resistant."
[0022] Staple fibers for use in spinning yarns are generally of a
particular length and of a particular linear density. For use in
this invention, synthetic fiber staple lengths of 2.5 to 15
centimeters (1 to 6 inches) and as long as 25 centimeters (10
inches) can be used, and lengths of 3.8 to 11.4 centimeters (1.5 to
4.5 inches) are preferred. Yarns made from such fibers having
staple lengths of less than 2.5 centimeters have been found to
require excessively high levels of twist to maintain strength for
processing. Yarns made from such fibers having staple lengths of
more than 15 centimeters are more difficult to make due to the
tendency for long staple fibers to become entangled and broken,
resulting in short fibers. The synthetic staple fibers can be
crimped or not, as desired for any particular purpose. The staple
fibers of this invention are generally made by cutting continuous
filaments to certain predetermined lengths. However, staple fibers
can be made by other means, such as by stretch-breaking, and yarns
can be made from such fibers as well as from a variety or
distribution of different staple fiber lengths.
[0023] In one embodiment of this invention, the yarn of this
invention can be used to make a flame retardant fabric, which is a
cloth produced by weaving, knitting, or otherwise combining the
yarn of this invention. Flame retardant fabrics can be constructed
having warp yarn comprising the yarns of this invention, fill yarn
comprising the yarns of this invention, or both warp and fill yarns
comprising the yarns of this invention. When fabrics use the yarn
of this invention in only one direction (i.e., as only fill or only
warp), other suitable yarns may be used in the other direction
according to the desired fabric characteristics. For best abrasion
resistance, the yarn of this invention is used in the warp
direction since warp yarn typically forms most of the direct
contact surface of a fabric. This translates into better abrasion
performance of the outer surface of the fabric in garment form.
[0024] In one embodiment of this invention, the flame retardant
fabric has a basis weight of from 4 and 15 ounces per square yard.
In another embodiment of this invention the flame retardant fabric
has a basis weight of from 5.5 to 11 ounces per square yard. Such
fabrics can be made into articles of clothing, such as shirts,
pants, coveralls, aprons, jacket, or any other single or
multi-layer form for flash fire or electric arc protection.
[0025] The articles of the invention will be further described
below with reference to the working examples. It should be noted
however that the concept of the invention will not be limited at
all by these examples.
TEST METHODS
[0026] The following test methods were used in the following
Examples.
[0027] Thermal Protective Performance Test (TPP)
[0028] The predicted protective performance of a fabric in heat and
flame was measured using the "Thermal Protective Performance Test"
(NFPA 2112). A flame was directed at a section of fabric mounted in
a horizontal position at a specified heat flux (typically 84
kW/m.sup.2). The test measures the transmitted heat energy from the
source through the specimen using a copper slug calorimeter with no
space between the fabric and heat source. The test endpoint was
characterized by the time required to attain a predicted
second-degree skin burn injury using a simplified model developed
by Stoll & Chianta, "Transactions New York Academy Science",
1971, 33 p 649. The value assigned to a specimen in this test,
denoted as the "TPP value," is the total heat energy required to
attain the endpoint, or the direct heat source exposure time to the
predicted burn injury multiplied by the incident heat flux. Higher
TPP values denote better insulation performance.
[0029] Vertical Flame Test
[0030] The "Vertical Flame Test" (ASTM D6413) is generally used as
a screening test to determine whether a fabric burns, as a
predictor for whether an article of clothing has any flame
retarding properties. According to the test, a 3.times.12 inch
section of fabric was mounted vertically and a specified flame was
applied to its lower edge for twelve seconds. The response of the
fabric to the flame exposure was recorded. The length of the fabric
that was burned or charred was measured. Times for afterflame
(i.e., the continued burning of the fabric section after removing
the test flame) and afterglow (characterized by smoldering of the
fabric section after removing the test flame) were also measured.
Additionally, observations regarding melting and dripping from the
fabric section were recorded. Pass/fail specifications based on
this method are known for industrial worker clothing, firefighter
turnout gear and flame retardant station wear, and military
clothing. According to industry standards, a fabric can be
considered flame retardant, or fire resistant, if it has a char
length of less than six inches after a twelve second exposure to a
flame.
[0031] Abrasion Resistance Test
[0032] Abrasion resistance was determined using ASTM method D3884,
with a H-18 wheel, 500 gms load on a Taber abrasion resistance
meter available from Teledyne Taber, 455 Bryant St., North
Tonawanda, N.Y. 14120. Taber abrasion resistance was reported as
cycles to failure.
[0033] Tear Strength Test
[0034] The tear strength measurement is based on ASTM D 5587. The
tear strength of textile fabrics was measured by the trapezoid
procedure using a recording constant-rate-of-extension-type (CRE)
tensile testing machine. Tear strength, as measured in this test
method, requires that the tear be initiated before testing. The
specimen was slit at the center of the smallest base of the
trapezoid to start the tear. The nonparallel sides of the marked
trapezoid were clamped in parallel jaws of a tensile testing
machine. The separation of the jaws was increased continuously to
apply a force to propagate the tear across the specimen. At the
same time, the force developed was recorded. The force to continue
the tear was calculated from autographic chart recorders or
microprocessor data collection systems. Two calculations for
trapezoid tearing strength were provided: the single-peak force and
the average of five highest peak forces. For the examples here, the
single-peak force was used.
[0035] Grab Strength Test
[0036] The grab strength measurement, which is a determination of
breaking strength and elongation of fabric or other sheet
materials, is based on ASTM D5034. A 100 mm (4.0 in.) wide specimen
was mounted centrally in clamps of a tensile testing machine and a
force applied until the specimen broke. Values for the breaking
force and the elongation of the test specimen were obtained from
machine scales or a computer interfaced with testing machine.
EXAMPLES
Example 1
[0037] A comfortable and durable fabric was prepared from warp
yarns comprising an intimate blend of NOMEX.RTM. type 462 staple
fiber, flame retardant (FR) rayon staple fiber, and nylon staple
fiber, and fill yarns comprising an intimate blend of FR rayon
staple fiber and nylon staple fiber. NOMEX.RTM. type 462 is 93% by
weight of poly(m-phenylene isophthalamide)(MPD-I) staple fiber, 5%
by weight poly(p-phenylene terephthalamide)(PPD-T) staple fiber,
and 2% by weight carbon-core nylon-sheath static dissipative staple
fibers (Type P-140 available from E.I. DuPont de Nemours of
Wilmington, Del.). FR rayon is a cellulosic fiber containing a
flame retardant compound, and the nylon was polyhexamethylene
adipamide. A picker blend sliver of 40 weight percent of NOMEX.RTM.
type 462 staple fiber, 45 weight percent of FR rayon staple fiber
and 15 weight percent of nylon staple fiber was prepared and
processed by the conventional cotton system into a spun yarn having
twist multiplier of 3.5 using a ring spinning frame. The yarn so
made was a 19.7 tex (30 cotton count) single yarn. Two single yarns
were then plied on a plying machine to make a two-ply yarn. Using a
similar process and the same twist and yarn density, a blend of 75
weight percent of FR rayon staple fiber and 25 weight percent nylon
fiber was used to make a two-ply yarn.
[0038] The NOMEX.RTM.)/FR rayon/nylon yarn was used as the warp
yarn and FR rayon/nylon yarn was used as the fill yarn in a shuttle
loom in a 3.times.1 twill construction. The greige twill fabric had
a construction of 36 ends.times.22 picks per cm (92 ends.times.57
picks per inch), and basis weight of 323 g/m.sup.2 (9.7
oz/yd.sup.2). The greige twill fabric prepared as described above
was scoured in hot water and dried under low tension. The scoured
fabric was then dyed using acid dye. The finished fabric was then
tested for its thermal and mechanical properties. The results of
these tests are shown in Table 1.
1TABLE 1 Example 1 Test Results Fabric Design Warp Yarn NOMEX
.RTM./FR Rayon/Nylon Fill Yarn 40/45/15% by Weight FR Rayon/Nylon
75/25% by Weight Test Description Units Value Basis Weight
oz/y.sup.2 9.7 Yarn Size count (warp .times. fill) 30/2 .times.
30/2 TPP cal/cm.sup.2 17.2 Vertical Flame inch (warp .times. fill)
4.7 .times. 2.4 Char Abrasion Cycle 1578 Tear Resistance lbf (warp
.times. fill) 26.6 .times. 11.0 Grab Strength lbf (warp .times.
fill) 191.0 .times. 97.8
Example 2
[0039] A comfortable and durable fabric was prepared as in Example
1, however, the warp yarns were made from 20 weight percent of
NOMEX.RTM. type 462 staple fiber, 55 weight percent of FR rayon
staple fiber, and 25 weight percent of nylon staple fiber, the spun
yarns having a twist multiplier of 3.7. The yarn so made was a 24.6
tex (24 cotton count) single yarn. Two single yarns were then plied
on the plying machine to make a two-ply yarn. Using a similar
process and the same twist as in Example 1, a single yarn was made
comprising a blend of 20 weight percent NOMEX.RTM. type 462 staple
fiber and 80 weight percent FR rayon staple fiber, having a linear
density of 32.8 tex (18 cotton count). Two of these yarns were then
plied to form a ply yarn.
[0040] The NOMEX.RTM./FR rayon/Nylon yarn and NOMEX.RTM./FR rayon
yarn were used as the warp and fill, respectively, in a shuttle
loom in a 3.times.1 twill construction. The greige twill fabric had
a construction of 26 ends.times.17 picks per cm (66 ends.times.44
picks per inch), and basis weight of 323 g/m.sup.2 (9.7
oz/yd.sup.2). The greige twill fabric prepared as described above
was scoured in hot water and dried under low tension. The scoured
fabric was then dyed using acid dye. The finished fabric was tested
for its thermal and mechanical properties. The results of these
tests are shown in Table 2.
2TABLE 2 Example 2 Test Results Fabric Design Warp Yarn NOMEX
.RTM./FR Rayon/Nylon Fill Yarn 20/55/25% by Weight NOMEX .RTM./FR
Rayon 20/80% by Weight Test Description Units Value Basis Weight
oz/y.sup.2 9.7 Yarn Size count (warp .times. fill) 24/2 .times.
18/2 TPP cal/cm.sup.2 16.9 Vertical Flame inch (warp .times. fill)
1.0 .times. 1.3 Char Abrasion Cycle 784 Tear Resistance lbf (warp
.times. fill) 18.3 .times. 14.8 Grab Strength lbf (warp .times.
fill) 121.1 .times. 124.9
Example 3
[0041] A fabric was prepared as in Example 1, however, both the
warp and fill yarns were made from 50 weight percent of NOMEX.RTM.
type 462 staple fiber, 35 weight percent of VISIL.RTM. staple
fiber, and 15 weight percent of nylon staple fiber, the spun yarns
having a twist multiplier of 3.7. The yarn so made was a 24.6 tex
(24 cotton count) single yarn. Two of these yarns were then plied
on the plying machine to make a two-ply yarn. Using the same fiber
composition, process, and twist multiplier, a single yarn of 32.8
tex (18 cotton count) was made. Two of these were then plied to
form a ply yarn.
[0042] The NOMEX.RTM./VISIL.RTM./nylon yarns were used as the warp
and fill in a shuttle loom in a 3.times.1 twill construction. The
greige twill fabric had a construction of 23 ends.times.16 picks
per cm (58 ends.times.40 picks per inch), and basis weight of 247.5
g/m.sup.2 (7.3 oz/yd.sup.2). The greige twill fabric prepared as
described above was scoured in hot water and dried under low
tension. The scoured fabric was then dyed using acid dye. The
finished fabric was tested for its thermal and mechanical
properties. The results of these tests are shown in Table 3.
3TABLE 3 Example 3 Test Results Fabric Design Warp Yarn NOMEX
.RTM./VISIL .RTM./Nylon Fill Yarn 50/35/15% by Weight NOMEX
.RTM./VISIL .RTM./Nylon 50/35/15% by Weight Test Description Units
Value Basis Weight oz/y.sup.2 7.3 Yarn Size count (warp .times.
fill) 24/2 .times. 18/2 TPP cal/cm.sup.2 14.4 Vertical Flame inch
(warp .times. fill) 3.7 .times. 3.2 Char Abrasion Cycle 558 Tear
Resistance lbf (warp .times. fill) 30.1 .times. 34.2 Grab Strength
lbf (warp .times. fill) 157.1 .times. 168.7
* * * * *