Note: Descriptions are shown in the official language in which they were submitted.
CA 02649935 2013-07-19
ULTRAVIOLET-RESISTANT FABRICS
BACKGROUND
Protective garments are often constructed from high-strength, inherently flame
resistant
fabrics, such as fabrics comprising aramid materials. Although such fabrics
are strong and,
therefore, can provide the desired degree of protection to the wearer, the
strength of these fabrics
can be compromised through exposure to ultraviolet (UV) rays, such as those
emitted by the sun
and other light sources. In fact, it is not unusual for the fabrics of such
garments to lose 50% or
more of their original strength after repeated exposure to daylight.
Unfortunately, protective garments of the type described above are often worn
outdoors.
For example, such garments are used by various utility personnel and other
industrial workers.
In such cases, the strength of the protective garment can decline as use of
the garment continues,
even over a relatively short period of time. This results in decreased
protection for the wearer, as
well as increased costs in replacing compromised garments.
In addition to reducing the strength of protective garments, UV exposure can
further
adversely affect the color of the gaiments. Specifically, UV exposure can
reduce the
colorfastness of such garments, causing their color to fade as the duration of
UV exposure
increases. Such fading is undesirable from an aesthetics point of view. In
some cases, however,
such fading can decrease the visibility of the garment, and therefore the
wearer. This
phenomenon is especially undesirable for high-visibility garments used near
roadways and other
hazardous areas in which failure to see the wearer may result in harm to that
wearer.
In view of the above, it would be desirable to be able to produce protective
fabric that has
greater resistance to UV radiation.
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=
SUMMARY OF THE INVENTION
According to the present invention, there is provided a fabric comprising
inherently flame resistant fibers and at least one ultraviolet-resistant
additive incorporated
into the inherently flame resistant fibers, the ultraviolet-resistant additive
comprising:
= a benzophenone compound, a benzoic acid compound, or a mixture thereof
or
= a hindered amine light (HAL) stabilizer
or both
= a benzophenone compound, a triazole compound, a benzoic acid compound, or
a
mixture thereof
and
= a hindered amine light (HAL) stabilizer
- the fabric further comprising aryl ether, benzyl alcohol, N-
cyclohexylpyrrolidone (CHP),
N,N-diethyl-m-toluamide (DEET), dimethylformamide (DMF), dibutyl acetamide
(DBA),
Isophorone, Acetophenone, Dibutylformamide incorporated into the inherently
flame
resistant fibers.
Disclosed are protective fabrics and methods for making protective fabrics. In
one
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embodiment, a protective fabric includes a plurality of inherently flame
resistant fibers, and
at least one ultraviolet-resistant additive incorporated into the inherently
flame resistant fibers
through a dye process using a carrier, wherein the ultraviolet-resistant
additive significantly
increases at least one of the strength retention and the colorfastness of the
fabric when
exposed to ultraviolet radiation.
In one embodiment, a method includes immersing a fabric in a mixture
comprising a
carrier and a ultraviolet-resistant additive, the fabric comprising a
plurality of inherently
flame resistant fibers, solublizing the ultraviolet-resistant additive with
the carrier so that the
ultraviolet-resistant additive is absorbed by the inherently flame resistant
fibers, wherein
absorption of the ultraviolet-resistant additive into the inherently flame
resistant fibers
significantly increases at least one of the strength retention and the
colorfastness of the fibers
when exposed to ultraviolet radiation.
BRIEF DESCRIPTION OF THE DRAWINGS
The fabrics of the present disclosure can be better understood with
reference to the following drawings. Features shown in these drawings are not
necessary
drawn to scale.
FIG. 1 is a front view of an example protective garment that is constructed of
a high-
strength, flame-resistant fabric.
FIG. 2 is a front view of a further example garment that is constructed of a
high-
strength, flame resistant fabric.
DETAILED DESCRIPTION
As is described above, the strength and/or colorfastness of fabrics used to
construct
protective garments can be significantly reduced due to ultraviolet (UV)
exposure. As is
described in the following, however, the resistance of such fabrics to UV
radiation can be
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significantly improved by incorporating UV-resistant additives into the fibers
of such fabrics.
When such additives are incorporated into the fabric fibers, the strength loss
and/or color
fading that can occur due to UV exposure can be reduced.
FIG. 1 illustrates an example protective garment 10. As is shown in that
figure, the
garment 10 comprises a firefighter turnout coat that can be donned by
firefighter personnel
when exposed to flames and extreme heat. As is indicated in FIG. 1, the
garment 10
generally comprises an outer shell 12 that forms the exterior surface of the
garment, a
moisture barrier 14 that forms an intermediate layer of the garment, and a
thermal liner 16
that forms the interior surface (i.e., the surface that contacts the wearer)
of the garment.
FIG. 2 illustrates a further example garment 18. The garment 18 comprises a
vest of
the type that may be worn by a utility lineman. As is indicated in FIG. 2, the
garment 18
includes an outer layer 20 of material, which may be dyed a bright shade that
is easily
identifiable for safety purposes. Optionally, the garment 18 includes
reflective (e.g.,
retroreflective) stripes 22, which aid observers in seeing the wearer of the
garment, especially
at night.
It is noted that, although a firefighter turnout coat and lineman vest are
shown in the
figures and described herein, other garments may benefit from the fabrics
described herein. Such garments may include one or more of shirts, pants,
jackets, coveralls,
vests, and the like that are intended for use in various different
applications. Moreover, the
present disclosure is not limited to garments. More generally, the present
disclosure pertains
to UV-resistant fabrics irrespective of their application.
The fabrics used to make the outer shell 12 of the garment 10 and the outer
layer 20 of
the garment 18 can comprise a high-strength, flame-resistant fabric. In some
embodiments,
the fabric comprises inherently flame resistant fibers that form the fabric
body. Examples of
such inherently flame resistant fibers include aramid (aromatic polyamide)
fibers, such as
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PCT/US2006/014960
meta-aramid fibers and para-aramid fibers.
Example meta-aramid fibers include those sold under the trademark Nomex by
DuPont, and fibers that are currently available under the trademark Conex by
Teijin.
Example para-aramid fibers include those that are currently available under
the
trademarks Kevla by DuPont, and Technora and Twaron by Teijin.
Other inherently flame resistant fibers suitable for construction of the
fabric include,
for example, polybenzoxazole (PBO), polybenzimidazole (PBI), melamine,
polyamide,
polyimide, polyimideamide, and modacrylic.
One or more other types of fibers may be blended with the inherently flame
resistant
fibers to construct the fabric. Examples of such fibers include cellulosic
fibers, such as
rayon, acetate, triacetate, and Iyocell. These cellulosic fibers, although not
naturally resistant
to flame, can be rendered flame resistant through application with an
appropriate flame
retardant. Generally speaking, cellulosic fibers that contain one or more
flame retardants are
given the designation "FR". Accordingly, the preferred flame resistant
cellulosic fibers
include FR rayon, FR acetate, FR triacetate, and FR lyocell.
Of the many blends conceivable using the above-described fibers, specific
examples
include 100% Nomex T-4558, 100% Nomex T-4628, 100% Nomex El 14 (Z-200), a
65/35 blend of Nomex T-4628 and FR rayon, a 60/40 blend of Nomex T-4620 and FR
rayon, a 60/40 blend of Kevlar T-9708 and Nomex T-4628, a 60/40 blend of
Kevlar T-9708
and PBI, an 80/20 blend of Nomex T-462 and PBI, a 60/20/20 blend of Kevlar T-
9708,
PBO, and Nomex T-4628, a 50/50 blend of meta-aramid and modacrylic, a 60/40
blend of
Kevlar Nomex T-9708 and Basofil (melamine), a 60/40 blend of meta-aramid and
para-
aramid, and 90/10 blend of meta-aramid and para-aramid. It is to be understood
that these
specific constructions are mere examples and are not intended to limit the
scope of the
present disclosure.
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The fabric can be dyed to a desired shade of color using customary dyeing
equipment.
Typically, a dye, a dye assistant (or "carrier"), and a flame retardant for
the non-inherently
flame resistant fibers (if applicable), are combined to form a mixture, (e.g.,
a dyebath,
solution, dispersion, or the like). Carriers aid in the absorption of dyestuff
into the fibers of
the fabric. In addition, some carriers aid in the solubilization of various UV-
resistant
additives that, as is discussed below, increase the UV resistance of the
fibers and, therefore,
the fabric. As an alternative to adding carrier to the mixture (e.g.,
dyebath), the carrier can
instead be imbibed into the fibers during fiber production. When the fibers
are imbibed with
carrier, dyeing is conducted in the typical manner, except that additional
carrier may not be
needed in the mixture.
Once the mixture is formed, the fabric is contacted with the mixture,
typically by
immersion, and the mixture is heated to fix the dye in the fibers. Although
the fabric has to
been described as being dyed in the piece, dyeing can be performed during
other stages of the
production process. Therefore, dyeing can be performed on the fibers, on yarn,
or on
substantially any fibrous textile, including sliver. Suitable equipment for
dyeing a textile
include, for example, jig dyeing machines, pad dyeing machines, beck dyeing
machines, and
jet dyeing machines.
In addition to dye, UV-resistant additives are incorporated into the fibers to
increase the fibers' resistance to UV radiation. One type of UV-resistant
additive is UV light
absorbers. UV light absorbers are materials that absorb LTV radiation to
reduce the
deleterious effects of that radiation on the medium (fibers in this case) in
which the absorber
is incorporated. Such UV light absorbers include, for example, benzophenone
compounds,
triazsole compounds, and benzoic acid compounds. Specific examples, of UV
light absorbers
include UvinulTM 3000 (2,4-dihydroxy-benzophenone), UvinulTM 3049 (2,2' -
dihydroxy-4,4'-
dimethoxybenzophenone), UvinulTM 3050 (2,2' -4,4' -tetrahydroxybenzophenone),
and UvinulTM
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3088 (2-propenoic acid,3-(40methoxypheny1)-,2-ethylhexylester), all from BASF;
Surftech
4500 (benzotriazole) from American Textile, LLC; and TinuvinTm 234 (2-(2H-
benzotriazol-2-
y1)-4,6-bis(1-methyl-1-phenylethyl)phenol),
TinuvinTm 327 (2-(3,5,Di-(tert)-buty1-2-
hydoxypheny1)-5-chlorobenzotriazole) and TinuvinTM 328 (2-
hydroxy-3,5-di-(ter)-
amylphenyl)benzotriazole) from Ciba Specitaty Chemicals.
Another type of UV-resistant additive that can be incorporated into the fibers
are
hindered amine light (HAL) stabilizers. Such HAL stabilizers include, for
example, amide
compounds and piperidine compounds. Specific examples include UvinulTM 4050H
(N,N'-1,6-
hexanediylbis(N-(2,2,6,6-tetramethyl-piperidinyl-formamide) from BASF, and
SanduvorTM
3058 Liquid (1 -acetyl-4- (3-dodecy1-2,5-dioxo-l-pyrro lidiny1)-2,2,6,6-
tetramethyl-piperidine
from Clariant.
Tests suggest that UV light absorbers are particularly effective in improving
fabric
strength retention, while HAL stabilizers are particularly effective in
improving fabric
colorfastness. Although they can be used separately, incorporation of both a
UV light
absorber and a HAL stabilizer into a given fabric can yield improved results
in terms of
strength retention and/or colorfastness. Specific examples of UV light
absorber/HAL
stabilizer blends include ChimasorbTM 119FL (ChimasorbTM 119 (complex
triazine) and
TinuvinTm 622 (succinate polymer with piperidineethanol)) and TinuvinTm 783LD
(TinuvinTm
622 and ChimasorbTM 944 (complex triazine)).
The UV-resistant additives can be incorporated into the fibers of the fabric
at nearly
any stage in the production process. Given that carriers that may be used as
dye assistants in
the dyeing process, it may be desirable to add the UV-resistant additives to
the fibers during
the dyeing process (assuming dyeing is performed). In such a case, the UV
light absorber(s)
can, for example, be provided in the mixture in a concentration of about 0.5 %
on weight of
fabric (owl) to about 6% owf, and the HAL stabilizer(s) can, for example, be
provided in the
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dyebath in a concentration from about 0.5% to about 3% owf. In some
embodiments,
concentrations of about 2% to 4% and 2% to 3% owf for UV light absorber and
HAL
stabilizer, respectively, are preferred. Examples of carriers that have been
determined to
solubilize UV light absorbers and/or HAL stabilizers include aryl ether,
benzyl alcohol, N-
cyclohexylpyrrolidone (CHP), N,N-diethyl-m-toluamide (DEET), dimethylformamide
(DMF), dibutyl acetamide (DBA), Isophorone, Acetophenone and Dibutylformamide.
A flame retardant compound can also be included in the mixture, applied as an
after-
dyeing surface treatment, or otherwise incorporated in the fibers of the
fabric to enhance
flame resistance or to counteract any deleterious effects of the carrier
contained within the
inherently flame resistant fibers. Furthermore, other chemicals can be applied
to the fibers
(e.g., added to the mixture) including lubricants, wetting agents, leveling
agents, and the like.
Testing was performed to examine the effectiveness of UV light absorbers and
HAL
stabilizers that were incorporated in the fibers of fabric during the dye
process. In that
testing, various samples of fabric were tested for strength according to test
methods described
in ASTM D5733-99 and ASTM D1424-96 both before and after exposure to UV
radiation
(daylight). Some of those samples had been treated with a UV light absorber, a
HAL
stabilizer, or both, while others (the "controls") were left untreated.
Table I provides strength retention data for this testing.
TABLE I: STRENGTH RETENTION
AFTER EXPOSURE TO UV RADIATION
Fabric Carrier UV Light HAL % Warp % Fill Days
Absorber (owl) Stabilizer Strength Strength
Exposed
(owl) Retention Retention
Nomex T-462 DEET, 30 0 0 81.2 80.4 14
(CONTROL) g/L
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Noxex T-462 DEET, 30 6% 0 92.0 88.7 14
benzophenone
compound
(Uvinul 3049)
Nomex T-462 CHP, 50 0 0 78.3 80.8 14
(CONTROL) g/L
Nomex T-462 CHP, 50 6% 0 89.7 86.8 14
g/L benzophenone
compound
(Uvinul 3049)
Nomex T-462 benzyl 0 0 77.1 67.4 14
(CONTROL) alcohol,
70g/L.
Nomex T-462 benzyl 6% 0 76.2 80.3 14
alcohol, benzophenone
70g/L compound
(Uvinul 3049)
Nomex T-462 aryl ether, 0 0 80.8 78.8 14
(CONTROL) 45 g/L
Nomex T-462 aryl ether, 6% 0 83.8 89.6 14
45 g/L benzophenone
compound
(Uvinul 3049)
65/35 Nomex T- CHP, 30 0 0 61.1 64.3 30
462/FR rayon g/L
(CONTROL)
65/35 Nomex T- CHP, 30 1% 0 76.0 73.1 30
462/FR rayon g/T-, benzophenone
compound
(Uvinul 3049)
65/35 Nomex T- CRP, 30 2% 0 81.3 86.0 30
462/FR rayon g/L benzophenone
compound
(Uvinul 3049)
65/35 Nomex CHP, 30 4% 0 86.0 86.7 30
T-462/FR rayon g/L benzophenone
compound
(Uvinul 3049)
65/35 Nomex CHP, 30 6% 0 79.1 89.5 30
T-462/FR rayon g/L benzophenone
compound
(Uvinul 3049)
60/40 Kevlar T- benzyl 0 0 52.7 45.1 14
970/ Nomex T-462 alcohol,
(CONTROL) 7 0 g / L
-
60/40 Kevlar T- benzyl 6% 0 66.7 58.4 14
970/ Nomex T-462 alcohol, benzophenone
70g/1., compound (UV-
3049)
60/40 Kevlar T- DEET, 30 0 0 61.2 61.6 14
970/ Nomex T-462 g/L
(CONTROL)
60/40 Kevlar T- DEET, 30 6% 0 74.6 69.6 14
970/ Nomex T-462 g/L benzophenone
compound ((JV-
3049)
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60/40 Kevlar T- CHIP, 50 0 0 63.1 56.7 14
970/ Nomex T-462 g/L
(CONTROL)
60/40 Kevlar T- CHIP, 50 6% 0 80.9 71.2 14
970/ Nomex T-462 g/L. benzophenone
compound (UV-
3049)
60/40 Kevlar T- CHIP, 50 6% triazole 0 78.7 78.0
14
970/ Nomex T-462 g/L compound
(Surftech 4500)
60/40 Kevlar T- CHIP, 20 4% 1% 73.7 66.7 30
970/ Nomex T-462 g/L benzophenone piperidine/
compound (UV- compound
3049) (Sanduvor
3058
Liquid)
60/40 Kevlar T- aryl ether, 0 0 56.3 58.7
14
970/ Nomex T-462 45 g/L
(CONTROL)
60/40 Kevlar T- aryl ether, 6% 0 68.2 - 68.4
14
970/ Nomex T-462 45 g/L benzophenone
compound (UV
3049)
60/40 Kevlar T- aryl ether, 1% 2% 74.7 65.6 30
970/ Nomex T-462 45 g/L benzophenone piperidine/
compound (UV- compound
3049) (Sanduvor
3058
Liquid)
Various phases of testing were conducted. In one such phase (Phase A), various
samples of 100% Nomex T-4628 were tested for strength after 14 days of
exposure to UV
radiation in the form of sunlight using the trap tear test described in ASTM
D5733-99. Each
sample was dyed or treated using a carrier, which comprised one of DEET, CHP,
benzyl
alcohol, and aryl ether. A control sample and a sample treated with a
benzophenone
compound (Uvinul 3049) were prepared using each carrier.
As can be appreciated from Table I, the samples that were treated with the
benzophenone compound UV light absorber typically exhibited greatly improved
strength
retention in both the warp and fill directions after UV exposure. On average,
each treated
sample exhibited 7.8% greater strength retention as compared to the controls
(i.e., 85.9%
average for treated samples, 78.1% average for non-treated samples), and
strength retention
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differences as high as 12.9% were observed.
In a second phase of the testing (Phase B), samples of a 65/35 blend of Notnex
T-
4628 and FR rayon were tested for strength after 30 days of exposure to
sunlight using the
Elmendorf test described in ASTM D1424-96. Each sample was dyed or treated
using a CHP
carrier, and each sample was treated with a different concentration of UV
light absorber
ranging from zero (i.e., for the control) to 6%. As is evident from the test
data, significant
strength retention increases were observed when the fabric was treated with
levels of UV light
absorber as low as 1% owf. In particular, the strength retention for the
sample treated with
1% benzophenone compound (Uvinul 3049) was 14.9% greater in the warp direction
and
8.8% greater in the fill direction as compared to the control sample. Greater
strength retention
was generally observed as the percentage of UV light absorber was increased.
In a third phase of the testing (Phase C), samples of a 60/40 blend of Kevlar
T-970
and Nomex T-4628 were tested for strength after 14 days, and in two cases 30
days, of
exposure to sunlight. The samples were treated with various carriers and UV
light absorbers.
In addition, two samples were treated with a HAL stabilizer (in the 30 day
exposure cases).
Again, the samples that were treated with the UV light stabilizers exhibited
increased strength
retention. The testing conducted for the samples containing a HAL stabilizer
appeared to
indicate that similar results are possible in cases in which the concentration
of UV light
absorber was reduced and the concentration of HAL stabilizer was increased.
Further testing was performed to examine the effectiveness of UV light
absorbers and
HAL stabilizers in improving colorfastness of fabrics that are exposed to UV
radiation. In
this testing, various samples of fabric were tested for colorfastness
according to AATCC Test
Method 16-2003 (Option 3). Some of those samples had been treated with a UV
light
absorber, a HAL stabilizer, or both, while others (i.e., the controls) were
left untreated. Table
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II provides colorfastness data for this testing.
TABLE II: COLORFASTNESS
AFTER EXPOSURE TO UV RADIATION
Fabric Dye UV Light HAL Stabilizer 20 hour 40 hour 60 hour
Assistant Absorber (owl) (owl) UV UV UV
60/40 Nomex T- CHP 0 0 3-4 3 2-3
462/FR rayon
(CONTROL)
60/40 Nomex T- CHP 2.0% 2.0% amide 4-5 4-5 4-5
462/FR rayon benzophenone compound
compound (Uvinul 4050H)
(Uvinul 3049)
60/40 Nomex T- CHP 5.0% 2.0% hindered 4-5 4-5 4-5
462/FR rayon benzophenone amide compound
compound (Sanduvor 3058
(Uvinul 3049) Liquid)
60/40 Nomex T- CHP 3.0% 3.0% amide 4-5 4-5 4-5
462/FR rayon benzophenone compound
compound (Uvinul 405011)
(Uvinul 3049)
60/40 Nomex T- CHP 0 2.0% hindered 4-5 4 4
462/FR rayon amide compound
(Sanduvor 3058
Liquid)
60/40 Nomex T- CHP 0 1.0% amide 4 4 3-4
462/FR rayon compound
(Uvinul 4050H)
60/40 Nomex T- CHP 0 2.0% amide 4 3-4 3-4
462/FR rayon compound
(Uvinul 405011)
60/40 Nomex T- CHP 1.0% 1.0% amide 3-4 3-4 3-4
462/FR rayon benzophenone compound
compound (Uvinul 4050H)
(Uvinul 3049)
60/40 Nomex T- CHP 1.0% 0 3-4 3-4 3
462/FR rayon benzophenone
compound
(Uvinul 3049)
60/40 Nomex T- CHP 0 1.0% hindered 3-4 3 3
462/FR rayon amide compound
(Sanduvor 3058
Liquid)
60/40 Kevlar T- aryl ether 0 0 3 2-3 2-3
970/
Nomex T-462
(CONTROL)
60/40 Kevlar T- aryl ether 3.0% 2.0% hindered 3-4 3
3
970/Nomex T- benzophenone amide compound
462 compound (Sanduvor 3058
(Uvinul 3049) Liquid)
60/40 Kevlar T- aryl ether 1.0% 1.0% amide 3-4 3 3
970/Nomex T- benzophenone compound
462 compound (Uvinul 4050H)
(Uvinul 3049)
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60/40 Kevlar T- aryl ether 1.0% 0 3-4 3 2-3
970/Nomex T- benzophenone
462 compound
(Uvinul 3049)
60/40 Kevlar T- CHIP 0 0 3 2-3 2-3
970/Nomex T-
462
(CONTROL)
60/40 Kevlar T- CHP 0 2.0% hindered 3-4 3 3
970/Nomex T- amide compound
462 (Sanduvor 3058
Liquid)
60/40 Kevlar T- CITP 1.0% 1.0% amide 34 3 3
970/Nomex T- benzophenone compound
462 compound (Uvinul 405011)
(Uvinul 3049)
60/40 Kevlar T- CEP 1.0% 1.0% hindered 3-4 3 3
970/Nomex T- benzophenone amide compound
462 compound (Sanduvor 3058
(Uvinul 3049) Liquid)
According to AATTCC Test Method 16-2003, colorfastness is rated from a scale
of 1
to 5, with "1" being the poorest colorfastness and "5" being the best
colorfastness. As can be
appreciated from Table II, the colorfastness of the fabrics treated with UV
light absorbers
and/or HAL stabilizers performed markedly better in terms of colorfastness as
compared to
the control fabrics.
While particular embodiments of the protective garments have been disclosed in
detail in the foregoing description and drawings for purposes of example, it
will be
understood by those skilled in the art that variations and modifications
thereof can be made.
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