U.S. patent application number 11/159379 was filed with the patent office on 2006-12-28 for flame-resistant fiber blend, yarn, and fabric, and method for making same.
This patent application is currently assigned to Springfield LLC. Invention is credited to John E. Ashley, Oscar M. Fuller.
Application Number | 20060292953 11/159379 |
Document ID | / |
Family ID | 37568166 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060292953 |
Kind Code |
A1 |
Ashley; John E. ; et
al. |
December 28, 2006 |
Flame-resistant fiber blend, yarn, and fabric, and method for
making same
Abstract
A fiber blend, a yarn spun from the fiber blend, and a fabric
made from the yarn, wherein the fiber blend comprises: (a) about 40
wt.% to about 65 wt.% modacrylic fibers containing antimony, or FR
acrylic fibers; (b) about 10 wt.% to about 50 wt.% cotton fibers or
FR cotton fibers; (c) up to about 25 wt.% nylon fibers; and (d)
greater than about 3 wt.% and less than 10 wt.% para-aramid fibers.
The fabric is over 90 percent dyeable and is capable of achieving
ASTM F1506 certification with an Arc Thermal Performance Value
greater than 8.0 cal/cm.sup.2. The fabric is woven or knitted, and
has a weight of about 4.0 oz./yd..sup.2 to about 10.5
oz./yd..sup.2. The fabric is suitable for garments worn during
activities in which there is potential for exposure to flame and/or
electrical arc.
Inventors: |
Ashley; John E.; (Gaffney,
SC) ; Fuller; Oscar M.; (Gaffney, SC) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
Springfield LLC
|
Family ID: |
37568166 |
Appl. No.: |
11/159379 |
Filed: |
June 22, 2005 |
Current U.S.
Class: |
442/197 ;
442/302; 442/310 |
Current CPC
Class: |
A41D 31/08 20190201;
D03D 15/593 20210101; D10B 2331/02 20130101; D10B 2331/021
20130101; D02G 3/047 20130101; Y10T 442/313 20150401; D10B 2201/02
20130101; Y10T 442/3984 20150401; Y10T 442/438 20150401; D10B
2321/101 20130101; D02G 3/443 20130101 |
Class at
Publication: |
442/197 ;
442/302; 442/310 |
International
Class: |
D03D 15/12 20060101
D03D015/12; D03D 15/00 20060101 D03D015/00 |
Claims
1. A flame-resistant fabric, the fabric being formed with yarn
comprising a blend of fibers, the blend comprising: about 40 wt.%
to about 65 wt.% modacrylic fibers containing antimony; about 10
wt.% to about 50 wt.% cotton fibers; up to about 25 wt.% nylon
fibers; and greater than about 3 wt.% and less than 10 wt.%
para-aramid fibers.
2. The flame-resistant fabric of claim 1, wherein the modacrylic
fibers contain at least about 7 wt.% antimony based on the weight
of the modacrylic.
3. The flame-resistant fabric of claim 1, wherein the blend
comprises: about 45 wt.% to about 55 wt.% modacrylic fibers; about
20 wt.% to about 30 wt.% cotton fibers; about 15 wt.% to about 20
wt.% nylon fibers; and about 5 wt.% to about 9 wt.% para-aramid
fibers.
4. The flame-resistant fabric of claim 1, wherein the blend
comprises: about 50 wt.% to about 55 wt.% modacrylic fibers; about
20 wt.% to about 25 wt.% cotton fibers; about 15 wt.% to about 20
wt % nylon fibers; and about 5 wt.% to about 7 wt.% para-aramid
fibers.
5. The flame-resistant fabric of claim 1, having a weight of about
4.0 oz./yd..sup.2 to about 10.5 oz./yd..sup.2.
6. The flame-resistant fabric of claim 1, having a weight of about
7.0 oz./yd..sup.2 to about 9.0 oz./yd..sup.2.
7. The flame-resistant fabric of claim 1, wherein the fabric is
woven.
8. The flame-resistant fabric of claim 1, wherein the fabric is
knit.
9. The flame-resistant fabric of claim 1, wherein the fibers are
dyed with basic dye to dye the modacrylic fibers and/or are dyed
with fiber reactive or direct dye to dye the cotton fibers.
10. A garment constructed from the flame-resistant fabric of claim
1.
11. A method of making a flame-resistant fabric, comprising the
steps of: forming an intimate blend of staple fibers comprising:
about 40 wt.% to about 65 wt.% modacrylic fibers containing
antimony; about 10 wt.% to about 50 wt.% cotton fibers; up to about
25 wt.% nylon fibers; and greater than about 3 wt.% and less than
10 wt.% para-aramid fibers; spinning the blend of staple fibers
into yarn; and knitting or weaving the yarn to form fabric.
12. The method of claim 11, further comprising the steps of: dyeing
the modacrylic fibers with basic dye; and dyeing the cotton fibers
with fiber reactive or direct dye.
13. The method of claim 12, wherein the dyeing steps are carried
out at a dye bath temperature not exceeding about 230.degree.
F.
14. The method of claim 12, wherein the blend of staple fibers
includes nylon fibers, and further comprising the step of dyeing
the nylon fibers with acid or disperse dye.
15. The method of claim 14, wherein the fibers are first dyed with
the basic dye, then the fibers are dyed with the fiber reactive or
direct dye, and finally the fibers are dyed with the acid or
disperse dye.
16. The method of claim 12, further comprising using a dye fixative
to fix the dyes.
17. The method of claim 11, further comprising the step of applying
a resin to the fabric for shrinkage control.
18. The method of claim 11, wherein the fabric is woven in a twill
pattern.
19. The method of claim 11, wherein the spinning step comprises
ring spinning the blend of staple fibers into yarn.
20. The method of claim 11, wherein the spinning step comprises air
jet spinning the blend of staple fibers into yarn.
21. The method of claim 11, further comprising the step of
calendering the fabric to reduce air permeability of the
fabric.
22. A blend of staple comprising: about 40 wt.% to about 65 wt.%
modacrylic fibers containing antimony; about 10 wt.% to about 50
wt.% cotton fibers; up to about 25 wt.% nylon fibers; and greater
than about 3 wt.% and less than 10 wt.% para-aramid fibers.
23. The blend of fibers of claim 22, wherein the modacrylic fibers
contain at least about 7 wt.% antimony based on the weight of the
modacrylic.
24. The blend of fibers of claim 22, wherein the blend comprises:
about 45 wt.% to about 55 wt.% modacrylic fibers; about 20 wt.% to
about 30 wt.% cotton fibers; about 15 wt.% to about 20 wt.% nylon
fibers; and about 5 wt.% to about 9 wt.% para-aramid fibers.
25. The blend of fibers of claim 22, wherein the blend comprises:
about 50 wt.% to about 55 wt.% modacrylic fibers; about 20 wt.% to
about 25 wt.% cotton fibers; about 15 wt.% to about 20 wt % nylon
fibers; and about 5 wt.% to about 7 wt.% para-aramid fibers.
26. A yarn formed from a blend of fibers comprising: about 40 wt.%
to about 65 wt.% modacrylic fibers containing antimony; about 10
wt.% to about 50 wt.% cotton fibers; up to about 25 wt.% nylon
fibers; and greater than about 3 wt.% and less than 10 wt.%
para-aramid fibers.
27. The yarn of claim 26, wherein the yarn is ring-spun.
28. The yarn of claim 26, wherein the yarn is air jet-spun.
29. The yarn of claim 26, wherein the yarn is open-end spun.
30. A flame-resistant fabric, the fabric being formed with yarn
comprising a blend of fibers, the blend comprising: about 40 wt.%
to about 65 wt.% FR acrylic fibers; about 10 wt.% to about 50 wt.%
FR cotton fibers; up to about 25 wt.% nylon fibers; and greater
than about 3 wt.% and less than 10 wt.% para-aramid fibers.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to flame-resistant fabrics
woven or knitted from yarns that are made from fiber blends.
[0002] Flame-resistant fabrics (also variously referred to as
"fire-resistant", "flame-retardant", and "fire-retardant" fabrics)
are fabrics that, once ignited, tend not to sustain a flame when
the source of ignition is removed. A great deal of investigation
and research has been directed toward the development and
improvement of flame-resistant fabrics for use in various products
such as bedding, clothing, and others. Flame-resistant clothing is
often worn by workers involved in activities such as industrial
manufacturing and processing, fire-fighting, electrical utility
work, and other endeavors that entail a significant risk of being
exposed to open flame and/or electrical arcs.
[0003] Flame-resistant fabrics include both fabrics that are
treated to be flame-resistant as well as flame-resistant fabrics
made from inherently flame-resistant fibers. The former types of
fabrics are not themselves flame-resistant, but are made
flame-resistant by applying to the fabric a chemical composition
that renders the fabric resistant to flame. These types of fabrics
are susceptible to losing their flame-resistance when laundered
repeatedly because the flame-resistant composition tends to wash
out. In contrast, inherently flame-resistant fabrics do not suffer
from this drawback because they are made from fibers that are
themselves flame-resistant.
[0004] Various types of inherently flame-resistant (FR) fibers have
been developed, including modacrylic fibers (e.g., PROTEX.RTM.
modacrylic fibers from Kaneka Corporation of Osaka, Japan), aramid
fibers (e.g., NOMEX.RTM. meta-aramid fibers and KEVLAR.RTM.
para-aramid fibers, both from E. I. Du Pont de Nemours and Company
of Wilmington, Del.), FR rayon fibers, oxidized polyacrylonitrile
fibers, and others. It is common to blend one or more types of FR
staple fibers with one or more other types of non-FR staple fibers
to produce a fiber blend from which yarn is spun, the yarn then
being knitted or woven into fabrics for various applications. In
such a fiber blend, the FR fibers render the blend flame-resistant
even though some fibers in the blend may themselves be non-FR
fibers, because when the FR fibers combust they release
non-combustible gases that tend to displace oxygen and thereby
extinguish any flame.
[0005] As an example, United States Patent Application Publication
US 2005/0025963 to Zhu discloses an intimate blend of staple fibers
having 10 to 75 parts by weight of at least one aramid fiber, 15 to
85 parts by weight of at least one modacrylic fiber, and 5 to 30
parts by weight of at least one polyamide fiber.
[0006] Another blend of staple fibers is disclosed in United States
Patent Application Publication US 2004/0192134 to Gibson et al. The
blend includes at least about 60 percent FR fibers (modacrylic
and/or aramid) and up to 40 percent synthetic or natural non-FR
fibers such as cotton or wool.
[0007] U.S. Pat. No. 6,787,228 to Campbell et al. discloses a yarn
formed of a blend of fibers including at least about 70 percent
modacrylic fibers combined with at least about 3 percent
high-performance, high-energy-absorptive fibers such as aramid.
[0008] In the United States, it is desirable and often required for
clothing worn by certain types of workers to pass standard
performance specification F1506 of the American Society for Testing
and Materials (ASTM). This standard, entitled "Standard Performance
Specification for Flame Resistant Textiles Materials for Wearing
Apparel for Use by Electrical Workers Exposed to Momentary
Electrical Arc and Related Thermal Hazards", sets various standard
performance specifications for a fabric, among which are
specifications for the ability of the fabric to self-extinguish
after being ignited. When the ignition source is removed, the
fabric must self-extinguish in less than 2 seconds and have less
than a 6-inch char length according to ASTM Test Method D6413
("Standard Test Method for Flame Resistance of Textiles", also
referred to as the Vertical Flame test). The F1506 performance
standard also includes standard test ASTM 1959 ("Standard Test
Method for Determining the Arc Thermal Performance Value of
Materials for Clothing"), which measures the level of protection
that the fabric provides against electrical arc exposure. The ASTM
1959 test establishes three levels of electrical arc protection as
measured by the fabric's Arc Thermal Performance Value (ATPV),
expressed in cal/cm.sup.2; at least Level II certification (ATPV
greater than 8.0 cal/cm.sup.2) is required for clothing worn by
many electrical utility workers. ASTM F1506 also has minimum
performance specifications for tensile breaking strength (40
pounds) and tear-resistance (4.0 pounds) of the fabric under
standard test conditions.
[0009] In addition to the above-noted performance specifications of
fabrics, other properties are also important if a fabric is to be
practical and commercially viable, particularly for clothing. For
instance, the fabric should be durable under repeated industrial
launderings and should have good abrasion-resistance. Furthermore,
the fabric should be readily dyeable to dark, solid shades of
color, and should be comfortable to wear.
[0010] As noted above, there are various fiber blends, yarns, and
fabrics that purport to provide some degree of flame-resistance.
However, the prior art known to the applicant does not disclose or
suggest the specific fiber blend and fabric of the present
invention, which has been found to possess distinct advantages and
characteristics, including passage of ASTM F1506 and Level II
certification for electrical arc protection. The fabric is also
comfortable to wear, is abrasion-resistant, is durable under
repeated industrial launderings, and is over 90 percent
dyeable.
BRIEF SUMMARY OF THE INVENTION
[0011] More particularly, the present invention provides a fiber
blend, a yarn made from the fiber blend, and a fabric made from the
yarn, wherein the fiber blend comprises: (a) about 40 wt.% to about
65 wt.% modacrylic fibers containing antimony, or FR acrylic
fibers; (b) about 10 wt.% to about 50 wt.% cotton fibers or FR
cotton fibers; (c) up to about 25 wt.% nylon fibers; and (d)
greater than about 3 wt.% and less than 10 wt.% para-aramid
fibers.
[0012] Advantageously, the modacrylic fibers contain at least about
7 wt.% antimony based on the weight of the modacrylic, and more
preferably at least about 10 wt.% antimony.
[0013] In one embodiment, the fiber blend comprises about 45 wt.%
to about 55 wt.% modacrylic fibers, about 20 wt.% to about 30 wt.%
cotton fibers, about 15 wt.% to about 20 wt.% nylon fibers, and
about 5 wt.% to about 9 wt.% para-aramid fibers.
[0014] A yarn in accordance with one embodiment of the invention
comprises the above-noted fiber blend spun into yarn. The yarn can
be spun in various ways, including ring spinning, air jet spinning,
and open-end spinning.
[0015] A fabric in accordance with one embodiment of the invention
has a weight of about 4.0 oz./yd..sup.2 to about 10.5
oz./yd..sup.2, more preferably about 7 oz./yd..sup.2 to about 9.0
oz./yd..sup.2. The fabric can be woven (e.g., a woven twill or
plain weave) or knitted. The invention also provides clothing made
from the fabric.
[0016] The fabric in accordance with the invention is dyeable to
dark or solid shades because the fiber blend is over 90 percent
dyeable. More specifically, the modacrylic fibers are dyeable with
basic dyes, the cotton fibers are dyeable with fiber-reactive or
direct dyes, and the nylon fibers (if present) are dyeable with
acid or disperse dyes. Only the para-aramid fibers are not dyeable,
and they comprise less than 10 percent of the fiber blend such that
they do not interfere with the attainment of solid shades.
Additionally, the fiber blend does not include any other fiber
types that would require dye procedures and/or processing
conditions that would be incompatible with the fiber constituents
of the blend. For example, the blend does not include meta-aramid
fibers because they require dye bath temperatures greater than
230.degree. F. and the use of a carrier that reacts negatively with
modacrylic.
[0017] The invention also provides a method for making a
flame-resistant fabric, comprising the steps of forming an intimate
blend of fibers comprising about 40 wt.% to about 65 wt.%
modacrylic fibers containing antimony, about 10 wt.% to about 50
wt.% cotton fibers, up to about 25 wt.% nylon fibers, and greater
than about 3 wt.% and less than 10 wt.% para-aramid fibers; forming
the blend of fibers into yarn; and knitting or weaving the yarn to
form fabric.
[0018] In another embodiment of the invention, the method further
comprises the steps of dyeing the fabric with basic dye to dye the
modacrylic fibers, and dyeing the fabric with fiber reactive or
direct dye to dye the cotton fibers. When nylon fibers are included
in the fiber blend, the dyeing steps also comprise dyeing the
fabric with acid or disperse dye to dye the nylon fibers. The
dyeing steps preferably are carried out by exhaust dyeing at a dye
bath temperature not exceeding about 230.degree. F. Preferably, the
fabric is first dyed with the basic dye, then the fabric is dyed
with the fiber reactive or direct dye, and finally the fabric is
dyed with the acid or disperse dye. Optionally, a dye fixative can
be used to fix one or more of the dyes.
[0019] The fabric made in accordance with the invention has an
advantageous combination of properties. The fabric is able to pass
the ASTM F1506 specification, and in fact can achieve a char length
of less than 5 inches, well under the 6-inch maximum permissible
value according to the specification. Additionally, the fabric can
achieve NFPA 70E Level II certification for protection against
electrical arc exposure. This is achievable with relatively low
fabric weights such that clothing made of the fabric is perceived
as being comfortable to wear; the inclusion of cotton provides
softness and moisture wicking, which further aids the comfort.
Cotton also forms a char that assists in the flame-resistance
performance. The nylon is included for durability and strength, as
well as the ability to be thermoset for shrinkage. It has also been
found that inclusion of nylon aids in improving the electrical arc
protection. The para-aramid is included for its inherent
flame-resistant properties, strength, and very low shrinkage even
with repeated industrial launderings. The cotton content also
allows the optional application of a resin to the fabric for
further shrinkage control, if desired or needed in a particular
instance. Furthermore, the fabric is over 90 percent dyeable such
that dark, solid shades can be achieved.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0020] The present inventions now will be described more fully
hereinafter with reference to particular embodiments and examples
of the inventions. However, these inventions may be embodied in
many different forms and should not be construed as limited to the
embodiments set forth herein; rather, these embodiments are
provided so that this disclosure will satisfy applicable legal
requirements.
EXAMPLES
[0021] Fabric samples were made from yarn spun from a blend of 50
wt.% modacrylic, 25 wt.% cotton, 20 wt.% nylon, and 5 wt.%
para-aramid staple fibers. The modacrylic fibers used for these
samples contained 10% antimony. The staple fibers had lengths
ranging from about 1.5 inches to about 2.0 inches. The modacrylic
fibers had a denier of 2.0, the nylon fibers had a denier of 1.8,
and the para-aramid fibers had a denier of 0.84. Two separate
batches of yarn were made from the fiber blend. One yarn was
ring-spun 25/2 cotton count yarn and the other yarn was air
jet-spun 25/2 cotton count yarn. Fabric was woven from each type of
yarn. The fabric constructions in each case were 76 warp ends/inch
and 56 picks/inch in a 2.times.1 right-hand twill pattern. The
fabric made with the ring-spun yarn weighed 8.2 oz./yd..sup.2 and
the fabric made with the jet-spun yarn weighed 8.6 oz./yd..sup.2.
The two types of fabric were tested according to ASTM F1506, and
the results are included in Table I below: TABLE-US-00001 TABLE I
WEIGHT ATPV.sup.1 FABRIC WIDTH (oz/yd) (cal/cm.sup.2) RING-SPUN
58-59'' 8.2 8.2 JET-SPUN 59-60'' 8.6 8.7 FLAMMABILITY.sup.2
DIMENSIONAL CHANGE.sup.3 -- AFTERFLAME DURATION CHAR LENGTH
IL@140.degree. F.* (secs.) (inches, warp/fill) (%, warp/fill) RING
JET RING JET RING JET ORIGINAL 0.00/0.00 0.00/0.00 5.5/4.2 4.4/4.4
After 5 IL 0.00/0.00 0.00/0.00 4.1/3.6 4.2/3.9 2.9/1.1 2.4/2.4
After 10 IL 0.00/0.00 0.00/0.00 4.1/3.6 3.5/3.5 0.4/0.7 0.8/0.3
After 25 IL 0.00/0.00 0.00/0.00 4.5/4.3 4.2/4.6 0.7/1.0 1.1/0.7
After 50 IL 0.00/0.00 0.00/0.00 5.1/5.1 4.6/4.7 1.9/1.3 1.5/2.1
After 75 IL 0.00/0.00 0.00/0.00 3.9/4.1 4.4/4.5 2.9/1.8 2.7/1.9
BREAKING STRENGTH.sup.4 TEAR-RESISTANCE.sup.5 FLEX.sup.6 (lbs,
warp/fill) (lbs, warp/fill) (cycles to failure, warp/fill) RING JET
RING JET RING JET ORIGINAL 209/132 200/127 13/9 11/7 8400/6500
9500/6300 After 5 IL 215/139 203/134 12/8 10/7 3600/4600 5300/5300
After 10 IL 196/130 209/136 10/6 11/8 5800/6200 3600/4500 After 25
IL 181/122 197/128 10/7 9/6 3100/4000 2500/3400 After 50 IL 203/135
181/116 9/6 8/5 2300/2600 2300/3300 After 75 IL 194/128 190/126 8/6
8/6 1400/1900 1600/1900 *Shrinkage was not performed on the same
sample at each interval .sup.1ASTM 1959 Standard Test Method for
Determining the Arc Thermal Performance Value of Materials for
Clothing .sup.2ASTM D6413 Standard Test Method for Flame Resistance
of Textiles (Vertical Test) .sup.3AATCC 96, Light Soil Release Wash
and Dry Procedure, described below. .sup.4ASTM D5034 Standard Test
Method for Breaking Strength and Elongation of Textile Fabrics
(Grab Test) .sup.5ASTM D1424 Standard Test Method for Tearing
Strength of Fabrics by Falling-Pendulum Type (Elmendorf) Apparatus
.sup.6ASTM D3885 Standard Test Method for Abrasion Resistance of
Textile Fabrics (Flexing and Abrasion Method)
[0022] The ASTM F1506 performance specification requires a fabric
to meet the following criteria:
[0023] Afterflame duration: 2 seconds maximum
[0024] Char length: 6 inches maximum
[0025] Breaking strength: 40 lbs. minimum
[0026] Tear-resistance: 4.0 lbs. minimum
[0027] Dimensional change: 3% maximum
[0028] ATPV .gtoreq.8.0 cal/cm.sup.2 for Arc Level II rating
[0029] The flammability test according to standard ASTM D6413
entails vertically suspending a fabric sample measuring 12 inches
long by 3 inches wide (with the length direction vertical) and
igniting the lower end of the fabric and then removing the source
of ignition. The duration of the afterflame following removal of
the ignition source is measured in seconds, and the char length of
the charred portion of the fabric is measured. The fabric is tested
in both warp and fill directions (i.e., samples having the length
direction parallel to the warp direction are tested and other
samples having the length direction parallel to the fill direction
are tested).
[0030] The dimensional change test entails subjecting fabric
samples to repeated laundering and drying cycles. At various
incremental numbers of cycles, the percent dimensional change of
the fabric is measured in both warp and fill directions, based on
benchmarks applied to the fabric prior to laundering. The
laundering and drying procedure was designed to substantially
duplicate a typical industrial laundering and drying process, and
comprised a Light Soil Release procedure, as follows:
[0031] Laundering Procedure--Light Soil Release (formulated for 15
lb. load) [0032] 1) Break, 12 gallon water level, 140.degree. F., 5
min., 1/3 cup Paragon Plus* [0033] 2) Carryover, 12 gallon water
level, 130-140.degree. F., 3 min., no chemicals [0034] 3) Rinse, 24
gallon water level, 120-130.degree. F., 1 min., no chemicals [0035]
4) Rinse, 24 gallon water level, 120-130.degree. F., 1 min., no
chemicals [0036] 5) Sour, 12 gallon water level, 90-100.degree. F.,
4 min., 1/4 oz. sodium silicofluoride (Fluor-o-cide)** [0037]
*Paragon Plus is a detergent available from Paragon Products, Inc.
[0038] **Sodium silicofluoride (Fluor-o-cide) is a product of UNX,
Inc. [0039] The procedure is to launder (in a Milnor washer),
centrifugal extract, and then dry at a temperature of
140-160.degree. F. for 20 minutes followed by 10 minute cool
down.
[0040] In the breaking strength test according to standard ASTM
D5034, the fabric sample is put into a machine that grips the
fabric with two clamps. One clamp is stationary and the other moves
away at a controlled slow rate, thus applying tension until the
fabric breaks or ruptures. The test is performed in both the warp
and fill directions. The highest tensile load in pounds just at the
moment the fabric breaks or ruptures is recorded.
[0041] The tear-resistance test according to standard ASTM D1424
measures the resistance of the fabric to tearing under a controlled
force. The test indicates the material's resistance to tearing when
there is an initial tear in the fabric. The fabric is tested in
both warp and fill directions.
[0042] The flex abrasion test according to standard ASTM D3885
measures the resistance of the fabric to abrasion under flexing. A
narrow strip of fabric is folded through 180.degree. around a
wear-resistant folding bar and held between two flat clamps.
Sufficient vertical loading is applied to prevent the fabric from
rippling while reciprocation loading parallel to the long dimension
of the tensioned fabric specimen is applied. The number of cycles
of abrasion to cause the specimen to break is determined.
[0043] Fabric made from each type of yarn was also tested for
electrical arc protection according to ASTM 1959. The fabric made
from ring-spun yarn was tested to have an ATPV of 8.2 cal/cm.sup.2.
The fabric using jet-spun yarn was tested to have an ATPV of 8.7
cal/cm.sup.2. Thus, both fabrics met the performance required for
NFPA 70E Level II certification.
[0044] As the results in Table I indicate, in the flame-resistance
test, the fabrics made in accordance with the invention
self-extinguished immediately and had char lengths well below the
maximum permissible 6 inches established by performance standard
ASTM F1506. The fabrics had less than 3 percent dimensional change
in both warp and fill directions after 75 industrial launderings at
140.degree. F. wash and dry temperatures. Breaking strength of both
fabrics was far in excess of the minimum 40 pound level required,
and tear-resistance was well in excess of the minimum 4.0 pound
level required, even after 75 industrial launderings. It is also
believed that fabrics made in accordance with the invention should
also be capable of meeting the more-stringent standards required
for NFPA 2112 certification (which includes the ASTM F1930 "Test
Method for Evaluation of Flame-Resistant Clothing for Protection
Against Flash Fire Simulations Using an Instrumented Manikin"), and
testing to verify this is currently in progress.
[0045] An additional fabric sample was made using the same fiber
constituent percentages as for the first two examples given above,
except that the 10% antimony modacrylic fibers were replaced by 15%
antimony PROTEX.RTM. M modacrylic fibers from Kaneka Corporation of
Osaka, Japan. The fiber blend was jet-spun into 25/2 cotton count
yarn, which was then woven into fabric using a 2.times.1 right-hand
twill pattern. The jet-spun yarn is more economical to produce than
ring-spun yarn, and the abrasion-resistance of fabric made with
jet-spun yarn is slightly better than that of fabric made with
ring-spun yarn. The wicking performance of the fabric was evaluated
using an industry-accepted test method, described below:
[0046] Wicking Test Procedure [0047] 1. Condition fabric (4 hours
at 65% relative humidity, 70.degree. F.) [0048] 2. Cut samples,
7''.times.1'', 2 in warp direction and 2 in fill direction [0049]
3. Draw lines with non-soluble ink across width of samples spaced
1'' apart [0050] 4. Place 500 ml of distilled water in a 600 ml
beaker [0051] 5. Hang the test specimen from a ring stand into the
beaker so that the narrow end of the fabric is immersed to a depth
of 1''. [0052] 6. Measure the distance the water has moved up the
fabric after 15 minutes [0053] 7. Report the average of the two
samples in each direction.
[0054] For the fabric as produced and prior to laundering, the
initial wicking performance was 4.25 inches in both the warp and
fill directions. After 50 industrial washes, the wicking
performance was 7.00+inches in the warp direction, and 6.25 inches
in the fill direction.
[0055] The dyeability properties of the fibers are also important.
An advantage of the fiber blend of the invention is that the
chemicals and temperatures required for dyeing the various types of
fibers do not interact negatively with each other. Advantageously,
the fabric contains less than 10 percent of the para-aramid fibers
(which are not dyeable), and thus is over 90 percent dyeable.
Therefore, dark, solid shades can be achieved by dyeing each of the
dyeable fiber types in the fabric. The dyes are all applied in an
exhaust dyeing procedure. The preferred dye procedure is to dye the
fabric (or the yarn from which the fabric is made) first with basic
dyes to dye the modacrylic fibers. Next the fabric or yarn is dyed
with fiber reactive or direct dyes to dye the cotton fibers.
Finally, the fabric or yarn is dyed with acid or disperse dyes to
dye the nylon fibers. The maximum temperature reached in the dye
bath is not greater than 230.degree. F. in each dyeing procedure.
The modacrylic fibers cannot withstand temperatures greater than
230.degree. F. Optionally, one or more dye fixatives can be used
for fixing one or more of the dyes.
[0056] Alternatively, fabric with a heather appearance can be
achieved by dyeing only some of the fiber types such as just the
modacrylic fibers.
[0057] The invention is susceptible to numerous variations within
the scope of the appended claims. As one example, a fiber blend
comprising 50 wt.% modacrylic, 25 wt.% cotton, 20 wt.% nylon, and 5
wt % para-aramid can be spun into yarn and the yarn can be made
into a 4.0 oz./yd..sup.2 plain weave for arc Level I certification.
An 8.3 oz./yd..sup.2 plain weave rip-stop fabric can also be made.
A 6.0 oz./yd..sup.2 plain weave rip-stop can also be made. These
are only some of the many variations that can be made within the
scope of the claims.
[0058] Fabric made in accordance with the invention may also be vat
dye printable. The military has a nylon/cotton product that it uses
for camouflage garments. The current fabric is not fire-resistant.
The fabric of the present invention may provide a fire-resistant
fabric containing nylon and cotton that is printable with a
camouflage pattern.
[0059] Another property of potential significance is the air
permeability of the fabric. It is thought that air permeability has
some effect on the performance of fabric in the electrical arc
test. The lower the air permeability, the better the fabric may
perform in that test. Samples of fabric in accordance with the
invention have been calendered to reduce the air permeability of
the fabric. A sample of fabric was tested for air permeability
after it was finished, after it was finished and sanforized, and
after it was finished, sanforized and calendered. The results were
17.0, 14.1, and 10.3 cfm, respectively. Thus, calendering can
significantly reduce the air permeability, which may be effective
in improving electrical arc protection provided by the fabric.
[0060] Fiber blends in accordance with the invention can be made
from fibers having various staple fiber lengths and various
deniers. Suitably, the fibers can range in length from about 0.5
inch to about 2.5 inches. The modacrylic, nylon, and para-aramid
fibers can have a denier ranging from about 0.5 to about 3.0. Yarns
can be made in accordance with the invention in various sizes, as
single-ply or two-ply yarn, although two-ply yarns are preferred
for strength and durability. With respect to two-ply yarns, the
yarns can vary in cotton count sizes from 64/2 to 15/2, more
preferably from about 38/2 to 15/2.
[0061] Finally, in another embodiment of the invention, the
modacrylic fibers can be replaced, in whole or in part, by
flame-resistant acrylic fibers and the cotton fibers can be
replaced, in whole or in part, by flame-resistant cotton fibers
treated in fiber or fabric form. For instance, the FR acrylic
fibers can comprise Lufnen acrylic fibers available from Kanebo of
Osaka, Japan. These fibers comprise a long-chain synthetic polymer
containing acrylonitrile groups modified with a
flame-retardant.
[0062] Many modifications and other embodiments of the inventions
set forth herein will come to mind to one skilled in the art to
which these inventions pertain having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the inventions are
not to be limited to the specific embodiments disclosed and that
modifications and other embodiments are intended to be included
within the scope of the appended claims. Although specific terms
are employed herein, they are used in a generic and descriptive
sense only and not for purposes of limitation.
* * * * *