Note: Descriptions are shown in the official language in which they were submitted.
CA 02830147 2013-09-13
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SPECIFICATION
METHOD FOR DYEING ARAMID FIBERS AND DYED ARAMID FIBERS
TECHNICAL FIELD
[0001]
The present invention relates to a method for dyeing
aramid fiber, in particular, to a method for dyeing which
can dye the aramid fibers with a practical color depth.
The present invention also relates to aramid fibers dyed by
the method.
BACKGROUND ART
[0002]
A wholly aromatic polyamide fiber is also called as
an aramid fiber, which has high strength and high modulus
of elasticity, and excellent heat resistance, dimensional
stability, chemical resistance, etc., and has been used for
wide uses as industrial use fibers. The aramid fibers can
be roughly classified into three kinds of para-type aramid
fibers (polyparaphenylene terephthalamide fiber, etc.),
para-type copolymerized aramid fibers (copolymerized fibers
with polyparaphenylene terephthalamide and 3,4'-
oxydiphenyleneterephthalamide), and, meta-type aramid
fibers (polymetaphenylene isophthalamide fibers or
copolymerized fibers containing the same as a main
component, etc.) depending on the position of an amide bond
attached to the aromatic ring.
[0003]
The para-type aramid fibers are particularly strong
and excellent in modulus of elasticity, and have been
widely used for protective clothes such as a bulletproof
jacket, etc., friction materials such as a brake pad, etc.,
reinforcing materials of an optical fiber, or industrial
materials such as ropes and nets which are required to have
particularly high strength. In addition, the para-type
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copolymerized aramid fibers have been used for the similar
uses as those of the para-type aramid fibers, and show
their characteristics for the uses required to have
chemical stability and fatigue resistance. It has been
widely used, for example, for rubber reinforcing materials,
ropes, and civil engineering and construction uses. On the
other hand, the meta-type aramid fibers are particularly
excellent in heat resistance, flame retardance, chemical
resistance, etc., and have been widely used for various
kinds of protective working clothes such as fire fighters'
suits, etc.
[0004]
These aramid fibers have rigid molecular structure
and high crystallinity, and a practical color depth cannot
be obtained by the same dyeing method as applied to the
general fibers, and colorfastness of the obtained dyed
product cannot be said to be practically sufficient. Thus,
in practical, it is manufactured as dope-dyed fibers
(fibers produced by adding a colorant at the stage before
the spinning step) and used mainly in the meta-type aramid
fibers. Such dope-dyed fibers are limited in hue, so that
there is the problem that they cannot sufficiently
correspond to various hues required for developing new
applications of various kinds of protective working clothes
or aramid fibers. Moreover, in the para-type aramid fibers
or the para-type copolymerized aramid fibers, and also
including the dope-dyed fibers, fibers having a practical
color depth such as black and navy blue have not yet been
industrially produced.
[0005]
On the other hand, it has been investigated a
specific dyeing method for dyeing the aramid fibers. For
example, there are a high temperature and high pressure
dyeing method which also uses a dyeing carrier such as
benzaldehyde, acetophenone and benzyl alcohol, or a solvent
dyeing method in which dyeing is carried out in a polar
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solvent such as N,N-dimethylformamide, dimethylsulfoxide
and cyclohexanone at high temperature. However, these
dyeing methods using a dyeing carrier or a polar solvent at
high temperatures are methods mainly for dyeing meta-type
aramid fibers, and they are insufficient for dyeing para-
type aramid fibers or para-type copolymerized aramid fibers.
Moreover, in the dyeing of the meta-type aramid fibers,
when the dyeing method which uses these dyeing carriers or
polar solvents at high temperature is employed, it involves
the problems of causing color unevenness of the dyed
product, and dimensional change or lowering in physical
properties due to shrinkage, etc.
[0006]
Thus, various novel dyeing methods have been
investigated even now. For example, in the following
Patent Document 1, it has been proposed a dyeing method in
which aramid fibers are pre-treated by conc. sulfuric acid,
subsequent to neutralization, injected into a dyeing bath
while maintaining a predetermined moisture content without
drying, and dyed by a disperse dye or a cationic dye. Also,
in the following Patent Document 2, a dyeing method in
which a part of vat dyes which are stable at high tempera-
ture is used, and dyeing is carried out at extremely high
temperature conditions of 300 to 400 C has been proposed.
PRIOR ART DOCUMENT
PATENT DOCUMENT
[0007]
Patent Document 1: JP Sho 52-37882A
Patent Document 2: JP 2010-59556A
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0008]
By the way, the dyeing method of the above-mentioned
Patent Document 1 gives a dyed product with various hues.
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However, the dyeing method of the above-mentioned Patent
Document 1 employs a dye such as a disperse dye and a
cationic dye, etc., and there is the problem that
colorfastness, in particular, colorfastness to light is bad.
To the contrary, the dyeing method of the above-mentioned
Patent Document 2 uses a vat dye which gives good
colorfastness to light, but a dyeing temperature is an
extremely high temperature whereby the dye which can be
used for the method is limited, so that there is the
problem that it cannot sufficiently correspond to various
hues.
[0009]
Also, the dyeing method of the above-mentioned Patent
Document 2 involves the problems that a specific device is
required and a cost for energy becomes large. Moreover,
the dyeing method of the above-mentioned Patent Document 2
is not yet sufficient to dye the para-type aramid fibers or
the para-type copolymerized aramid fibers with a practical
color depth. On the other hand, when the dyeing method of
the above-mentioned Patent Document 2 is applied to the
meta-type aramid fibers, the fibers are treated at a
temperature markedly higher than the glass transition
temperature thereof, so that there is the problem that the
physical properties of the fibers are markedly lowered.
[0010]
Thus, the present invention has been done in view of
the above mentioned problems, and an object thereof is to
provide a method for dyeing aramid fibers and dyed aramid
fibers, which method is a dyeing method which can be
applied to either of the para-type aramid fibers, the para-
type copolymerized aramid fibers and the meta-type aramid
fibers, which can be dyed to a practical color depth
required for developing new applications of the aramid
fibers, and color unevenness, dimensional change, or
lowering in physical properties are not generated so
remarkably in the aramid fibers after dyeing, further,
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colorfastness of the dyed product, in particular,
colorfastness to light is good.
MEANS TO SOLVE THE PROBLEMS
[0011]
To solve the above-mentioned problems, the present
inventors have intensively studied, and as a result, they
have found that the above-mentioned problems can be solved
by employing a vat dye or a sulfur dye which has good
colorfastness to light for dyeing aramid fibers, and using
a step of providing these dyes onto the aramid fibers, and
a step of treating the aramid fibers with a polar solvent
in combination, whereby the present invention has been
accomplished.
[0012]
That is, a method for dyeing aramid fibers according
to the present invention comprises, according to the
definition of claim 1, a dye providing step in which a vat
dye or a sulfur dye is provided to aramid fibers, a solvent
treatment step in which the aramid fibers are treated by a
treating solution containing a polar solvent, and
after the solvent treatment step, a heat treatment step in
which the aramid fibers are subjected to a heat treatment,
if necessary, and having at least one dyeing operation
among the following four dyeing operations ("-," denotes
"followed by"),
dyeing operation 1: dye providing step -> solvent treatment
step,
dyeing operation 2: solvent treatment step dye providing
step,
dyeing operation 3: dye providing step -> solvent treatment
step heat treatment step,
dyeing operation 4: solvent treatment step -> heat treatment
step dye providing step,
once or more.
[0013]
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Also, the present invention is, according to the
definition of claim 2, in the method for dyeing aramid
fibers according to claim 1, wherein the polar solvent has
a value of a solubility parameter (6) within a range of 18
to 32 (MPa)112.
[0014]
Further, the present invention is, according to the
definition of claim 3, in method for dyeing aramid fibers
according to claim 1, wherein the polar solvent is at least
one selected from the group consisting of N-methylpyrroli-
done, N,N-dimethylformamide, N,N-dimethylacetamide,
dimethylsulfoxide, benzyl alcohol, diethylene glycol,
triethylene glycol, sulfuric acid, formic acid, lactic acid
and oxalic acid.
[0015]
Moreover, a method for dyeing aramid fibers according
to the present invention comprises, according to the
definition of claim 4, the method for dyeing aramid fibers
according to any one of claims 1 to 3, and a pre-dyeing
step which is carried out before the method for dyeing or a
post-dyeing step which is carried out after the same,
wherein the aramid fibers are dyed by a dye other than the
vat dye and the sulfur dye in the pre-dyeing step or in the
post-dyeing step.
[0016]
Furthermore, dyed aramid fibers according to the
present invention comprise, according to the definition of
claim 5, dyed by the method for dyeing aramid fibers
according to any one of claims 1 to 3.
[0017]
In addition, the present invention is, according to
the definition of claim 6, in the dyed aramid fibers
according to claim 5, lightness (L* value) in an L*a*b*
colorimetric system is 38 or less.
[0018]
Also, the present invention is, according to the
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definition of claim 7, in the dyed aramid fibers according
to claim 5, wherein lightness (L* value) in an L*a*b*
colorimetric system is 30 or less.
[0019]
Further, the dyed aramid fibers according to the
present invention comprise, according to the definition of
claim 8, fibers dyed by the method for dyeing aramid fibers
according to claim 4.
[0020]
Moreover, the present invention is, according to the
definition of claim 9, in the dyed aramid fibers according
to claim 8, wherein lightness (L* value) in an L*a*b*
colorimetric system is 30 or less.
EFFECTS OF THE INVENTION
[0021]
According to the present invention, the method can be
applied to either of the para-type aramid fibers, the para-
type copolymerized aramid fibers or the meta-type aramid
fibers, and can dye these aramid fibers with a practical
color depth. Also, according to the present invention,
color unevenness or dimensional change, or lowering in
physical properties is not markedly generated in the aramid
fibers after the dyeing. Moreover, since a vat dye or a
sulfur dye having good colorfastness, in particular,
colorfastness to light is used, colorfastness, in
particular, colorfastness to light of the dyed aramid
fibers becomes good.
[0022]
In addition, by changing a used concentration and hue
of the vat dye or the sulfur dye to be used, a dyed product
from a pale color to a dark color with various hues can be
obtained. In particular, according to the present
invention, the para-type aramid fibers or the para-type
copolymerized aramid fibers can be dyed with a very dark
color such as black and navy blue which had been deemed to
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be difficult.
[0023]
Here, as one of the methods to evaluate a dark color
such as black and navy blue, there is lightness (L* value)
in a L*a*b* colorimetric system which had been standardized
by International Commission on Illumination (CIE) in 1976,
and in Japan, it had been adopted in JIS Z8729. This L*
value is shown in the range of 100 (white) to 0 (black),
and a smaller L* value can be evaluated to be a dark color.
[0024]
For example, in the dope-dyed fibers of the
commercially available meta-type aramid fibers or para-type
copolymerized aramid fibers, it has been obtained an L*
value of 25 to 27 in the very dark color such as black and
navy blue. Accordingly, in the present invention, the L*
value of 38 or less can be judged as a dark color, and
further, the L* value of 30 or less can be judged as a very
dark color. In the present invention, not only the meta-
type aramid fibers but also the para-type aramid fibers or
the para-type copolymerized aramid fibers can be dyed to a
dark color or a very dark color not by the spun-dyeing
method but by the dyeing method.
[0025]
Also, as a step before or after the method for dyeing
aramid fibers according to the present invention, a pre-
dyeing step or a post-dyeing step by a dye other than the
vat dye and the sulfur dye can be carried out. By carrying
out these dyeing steps, fuzz at the surface of the aramid
fibers themselves is more sufficiently dyed, so that dyeing
quality and color depth are further improved. On the other
hand, when the aramid fibers are mixed with the other
chemical fibers or natural fibers to form a mixed fiber,
hue of the aramid fibers and that of the other fibers can
be unified by subjecting to these dyeing steps, whereby the
dyeing quality and the color depth of the dyed product are
further improved.
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[0026]
Thus, according to the present invention, a method
for dyeing aramid fibers and dyed aramid fibers having good
colorfastness, in particular, colorfastness to light of the
dyed product, abundant in hue and a practical color depth
can be provided. This is effective for developing novel
use of the aramid fibers.
EMBODIMENTS TO CARRY OUT THE INVENTION
[0027]
In the aramid fibers to be dyed by the dyeing method
according to the present invention, for example, as the
para-type aramid fibers, there may be mentioned Twaron
(Registered Trademark) available from Teijin Limited, and
Kevlar (Registered Trademark) available from Du Pont
Kabushiki Kaisha, and as the para-type copolymerized aramid
fibers, there may be mentioned Technora (Registered
Trademark) available from Teijin Limited. On the other
hand, as the meta-type aramid fibers, there may be
mentioned Conex (Registered Trademark) available from
Teijin Limited, and Nomex (Registered Trademark) available
from Du Pont Kabushiki Kaisha.
[0028]
In the present invention, the aramid fibers may be
any form, and may be in the state of fibers such as
filament fibers, staple fibers, etc., or in the state of a
fiber structure such as filament yarn, spun yarn, fabrics,
knitted fabrics, non-woven fabrics, rope, a net, etc. Also,
it may be either one of the para-type aramid fibers, the
para-type copolymerized aramid fibers or the meta-type
aramid fibers, or in the state of mixed fibers thereof.
Moreover, it may be in the state of mixed fibers of the
aramid fibers and the other chemical fibers or natural
fibers.
[0029]
In the present invention, the aramid fibers are dyed
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by a vat dye or a sulfur dye. These vat dyes or sulfur
dyes are each dyes having good colorfastness, in particular,
excellent in colorfastness to light.
[0030]
Here, the vat dye is generally used for dyeing of
cotton, etc., and is a dye essentially insoluble in water,
but it is reduced by a reducing agent such as sodium
dithionite, etc., to adsorb to the fibers in the form of
leuco acid or leuco salt, and thereafter, is oxidized and
dyeing to the fibers as a dye insoluble in water again.
[0031]
On the other hand, the sulfur dye is a dye containing
a sulfur atom in the molecule, and is generally used for
dyeing of cotton, etc. This sulfur dye is also a dye
essentially insoluble in water, but it is reduced by a
reducing agent such as sodium sulfide, etc., to become
water-soluble to adsorb to the fibers, and thereafter, is
oxidized and dyeing to the fibers as a dye insoluble in
water again.
[0032]
However, in the present invention, the vat dye or the
sulfur dye is used without reduction and dyed to the aramid
fibers in the state of a dye insoluble in water. The vat
dye or the sulfur dye does not have potent affinity as it
were, which can dye to the aramid fibers as such. Also,
when the vat dye or the sulfur dye is reduced to make it
water-soluble, affinity to the aramid fibers is further
lowered.
[0033]
In the present invention, however, by employing a
solvent treatment of the aramid fibers using a polar
solvent in combination, it can be considered that dyeing
property of the vat dye or the sulfur dye to the aramid
fibers would be revealed. Further, when a heat treatment
is carried out, if necessary, after the solvent treatment,
dyeing property of the vat dye or the sulfur dye to the
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,
aramid fibers is improved in some cases. However, at the
present stage, it is not yet clear about the dyeing
mechanism of the vat dye or the sulfur dye to the aramid
fibers according to the present invention.
[0034]
In the following, the method for dyeing aramid fibers
according to the present invention will be explained based
on the respective embodiments.
(1) First embodiment
The dyeing method according to the first embodiment
comprises a dye providing step in which a vat dye or a
sulfur dye is provided to the aramid fibers, and a solvent
treatment step in which the aramid fibers are treated by a
treating solution containing a polar solvent. The order of
these dye providing step and solvent treatment step is not
particularly limited, and it is preferred to carry out the
solvent treatment step after the dye providing step. In
this first embodiment, the dye providing step in which the
vat dye or the sulfur dye is provided to the aramid fibers
in a non-reduced state is firstly carried out, subsequently
the solvent treatment step in which the aramid fibers to
which the vat dye or the sulfur dye had been provided are
treated by a treating solution containing a polar solvent
is carried out.
[0035]
In this first embodiment, these series of steps are
generically called as "dyeing operation 1". Incidentally,
this dyeing operation 1 (dye providing step solvent
treatment step) may be carried out only once, or may be
repeated a plural number of times, depending on necessity.
By repeating this dyeing operation a plural number of times,
aramid fibers with a denser color can be obtained.
[0036]
A. Dye providing step
The vat dye to be used in the dye providing step may
be mentioned a dye generally used for dyeing of cotton, etc.
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Also, in the present invention, it is preferred to use a
super fine dye having an average dispersed particle
diameter in the state of dispersing in a dyeing solution of
several Am or less, more preferably 1 Am or less. In
addition, among these vat dyes, it is more preferred to use,
in particular, each dye of C.I. Vat Yellow 33, C.I. Vat
Brown 1, C.I. Vat Red 1, C.I. Vat Violet 9, C.I. Vat Blue 4,
C.I. Vat Blue 6, C.I. Vat Blue 20, C.I. Vat Green 1, C.I.
Vat Green 3, C.I. Vat Black 8, C.I. Vat Black 25, etc.
[0037]
On the other hand, the sulfur dye to be used in the
dye providing step may be mentioned a dye generally used
for dyeing of cotton, etc. Also, among these sulfur dyes,
it is more preferred to use, in particular, each dye of C.I.
Sulphur Yellow 16, C.I. Sulphur Orange 1, C.I. Sulphur Red
6, C.I. Sulphur Blue 7, C.I. Sulphur Blue 15, C.I. Sulphur
Black 11, etc.
[0038]
At the stage of providing a dye to the aramid fibers,
the vat dye or the sulfur dye is not in a reduced state,
and is a dye insoluble in water. Accordingly, for
providing a dye to the aramid fibers in the dye providing
step, a dyeing solution in which the vat dye or the sulfur
dye is dispersed in water is used. In this dyeing solution,
the vat dye or the sulfur dye is contained in a non-reduced
dispersed state, and, if necessary, a migration preventive
agent may be used therein in combination. For providing
the dyeing solution, any methods may be employed, and may
be simple dipping, dipping and squeezing liquid, or may be
provision by spray, ink jet, etc.
[0039]
The aramid fibers to which the dyeing solution had
been provided are dried thereafter, if necessary. Drying
of the aramid fibers may be carried out at any temperatures,
and generally dried at a temperature of about 80 C to 120 C.
In addition, after drying the aramid fibers, a heat
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treatment (which is different from the heat treatment step
mentioned below) may be further carried out at high
temperature. Or else, the aramid fibers to which the
dyeing solution had been provided may be subjected to a
heat treatment at a temperature of about 120 C to 200 C, or
a higher temperature than the above, which also acts as
drying procedure.
[0040]
If the drying temperature is lower than 80 C, a
longer time is required for drying the aramid fibers. On
the other hand, if the treatment temperature is higher than
200 C, in particular, it is higher than 280 C, lowering in
physical properties of the aramid fibers occurs remarkably
in some cases. In particular, in the case of the meta-type
aramid fibers, a heat treatment at a temperature exceeding
its glass transition temperature causes lowering in
physical properties. In addition, it is treated at an
extremely high temperature, the vat dye or the sulfur dye
decomposes in some cases whereby hue is markedly changed.
[0041]
On the other hand, the drying time may be optionally
selected depending on a kind or a form of the aramid fibers,
and a drying temperature, and is not a particular problem.
The drying time is generally a time of about 30 seconds to
30 minutes. For example, when the aramid fibers are
fabrics, the drying time is preferably about 1 minute to 10
minutes when the drying temperature is 105 C.
[0042]
At the stage where the drying has finished, the vat
dye or the sulfur dye is in the state that they are
uniformly provided onto the aramid fibers. However, the
aramid fibers are not in the state that they are completely
dyed by the vat dye or the sulfur dye. However, at this
stage, the vat dye or the sulfur dye is attached to the
aramid fibers with a certain degree of affinity, whereas it
is not yet reached to dyeing. Here, the reason why the vat
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dye or the sulfur dye is attached to the aramid fibers is
not clear, but it can be considered that these dyes are
attached onto the surface of the aramid fibers by physical
action such as an intermolecular force in an unreduced
water-insoluble state.
[0043]
Here, when the aramid fibers are a fabric state, a
series of the treatments can be carried out by running the
fabrics to the longitudinal direction. In this case, the
running aramid fiber fabrics are firstly dipped in a bath
in which a dyeing solution has been filled. Subsequently,
an excess dyeing solution is squeezed from the aramid fiber
fabrics by a squeezing means such as mangle, etc.
According to these procedures, aramid fiber fabrics to
which a predetermined amount of the dyeing solution has
been provided are obtained. Next, the aramid fiber fabrics
after squeezing is introduced in a heat treatment device
such as a pin tenter while running and dried therein.
[0044]
B. Solvent treatment step
The aramid fibers after the dye providing step are
injected into the subsequent solvent treatment step without
washing. In the solvent treatment step, the aramid fibers
are treated by a polar solvent. In the present invention,
the polar solvent is widely interpreted, and is to be
called a substance having a polar functional group in the
molecular structure of a solvent. For example, among the
polar solvents, an aprotic polar solvent may be mentioned
N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethyl-
acetamide, dimethylsulfoxide, acetophenone, methyl ethyl
ketone, N-butylphthalamide, N-isopropylphthalamide, N-
methylformanilide, etc. These aprotic polar solvents may
be used alone, or in combination of two or more, or may be
used by formulating with the following mentioned protonic
polar solvent (s). Among these aprotic polar solvents, as a
solvent which difficultly causes shrinkage or lowering in
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physical properties of the aramid fibers, and particularly
effective for dyeing the vat dye or the sulfur dye, N-
methylpyrrolidone, N,N-dimethylformamide, N,N-
dimethylacetamide and dimethylsulfoxide are preferably
mentioned.
[0045]
Also, among the polar solvents, the protonic polar
solvent may be mentioned protonic acids such as sulfuric
acid, formic acid, lactic acid, maleic acid, oxalic acid,
etc.; alcohols such as 1-propanol, 1-octanol, benzyl
alcohol, DL-g-ethylphenethyl alcohol, 2-ethoxybenzyl
alcohol, 3-chlorobenzyl alcohol, 2,5-dimethylbenzyl alcohol,
2-nitrobenzyl alcohol, p-isopropylbenzyl alcohol, 2-methyl-
phenethyl alcohol, 3-methylphenethyl alcohol, 4-methyl-
phenethyl alcohol, 2-methoxybenzyl alcohol, 3-iodobenzyl
alcohol, cinnamic alcohol, p-anisyl alcohol, benzhydrol, 2-
(4-chlorophenoxy)ethanol, 2-(4-chlorophenoxyethoxy)ethanol,
2-(dichlorophenoxy)ethanol, etc.; glycols such as ethylene
glycol, diethylene glycol, triethylene glycol, PEG200,
PEG400, PEG600, propylene glycol, polypropylene glycol,
etc., and further a monoether or monoester of the glycol
such as ethylene glycol monomethyl ether, diethylene glycol
monomethyl ether, ethylene glycol monoethyl ether,
diethylene glycol monoethyl ether, ethylene glycol
monophenyl ether, diethylene glycol monophenyl ether,
propylene glycol monomethyl ether, dipropylene glycol
monomethyl ether, propylene glycol monoethyl ether,
dipropylene glycol monoethyl ether, propylene glycol
monophenyl ether, dipropylene glycol monophenyl ether,
cellosolve, n-butyl cellosolve, hydroxyethyl acrylate, etc.
These protonic polar solvents may be used alone, or in
combination of two or more, or may be used by formulating
with the above-mentioned aprotic polar solvent(s). Among
these protonic polar solvents, as a solvent which
difficultly causes shrinkage or lowering in physical
properties of the aramid fibers, and particularly effective
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for dyeing the vat dye or the sulfur dye, benzyl alcohol,
diethylene glycol, triethylene glycol, sulfuric acid,
formic acid, lactic acid and oxalic acid are preferably
mentioned.
[0046]
Also, as a quantitative index which shows polarity of
the polar solvent used in the present invention, a
solubility parameter (6) can be used. In the present
invention, it is preferred to use a polar solvent having a
value of the solubility parameter within the range of 6=18
to 32 (MPa)1/2. Moreover, it is more preferred to use a
polar solvent having a value of the solubility parameter
within the range of 6=19 to 28 (MPa)1/2. Here, for example,
the value of the solubility parameter of the para-type
aramid fibers is to be made 6=23 (MPa)1/2 (J.E. Mark,
Physical Properties of Polymers Handbook. New York:
Woodbury, 1996.). Accordingly, it seems that an action of
the polar solvent to the aramid fibers is caused by the
fact that the value of the solubility parameter of the
polar solvent is within the above-mentioned range, which is
close to the value of the solubility parameter of the
aramid fibers. According to the fact, dyeing property of
the vat dye or the sulfur dye to the aramid fibers is
improved, whereby aramid fibers having a more practical
color depth can be obtained.
[0047]
These polar solvents may be used alone or may be used
by mixing two or more solvents as mentioned above. Also, a
concentration of the polar solvent to be used in the
solvent treatment may be optionally selected depending on a
kind or a shape of the aramid fibers to be treated, and a
treatment temperature, and in general, it is preferred to
contain 40% by weight to 100% by weight, and more
preferably to contain 50% by weight to 100% by weight.
Please be noted that oxalic acid is a solid generally
having crystal water, and its solubility is a little. Thus,
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as far as the oxalic acid is concerned, it is preferred to
use as an aqueous solution of about 10% by weight.
[0048]
On the other hand, with regard to sulfuric acid to be
used in the manufacturing step of the para-type aramid
fibers, it is necessary to set the concentration to be used
to narrower. In this solvent treatment step, it is
preferred to use an aqueous sulfuric acid solution with a
concentration of 70% by weight to 90% by weight. Moreover,
it is further preferred to use an aqueous sulfuric acid
solution with a concentration of 75% by weight to 85% by
weight.
Also, when the aramid fibers mainly comprise the
meta-type aramid fibers, it is more preferred to use an
aqueous sulfuric acid solution with a concentration of 75%
by weight to 80% by weight.
[0049]
When the concentration of the polar solvent is within
the above-mentioned range, the color depth becomes within a
relatively stable range, and even if the concentration of
the polar solvent is slightly fluctuated, the color depth
is not so remarkably changed. Accordingly, stable
industrial production can be done when the concentration of
the polar solvent is within the above-mentioned range.
[0050]
Here, a diluent of the polar solvent may be used any
material so long as it has compatibility with the polar
solvent to be used, and water is generally used. In the
case of a certain kind of the polar solvent, for example,
N-methylpyrrolidone, etc., by mixing a certain amount of
water, a denser dyed product can be obtained. On the other
hand, if the concentration of the polar solvent is lower
than the above-mentioned range, and an amount of water in
the solvent treatment solution is increased, it is not
preferred since the vat dye or the sulfur dye attached to
the aramid fibers in the dye providing step drops into the
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solvent treatment solution in some cases.
[0051]
A treatment temperature of the polar solvent may be
optionally selected depending on a kind or a shape of the
aramid fibers to be treated, and a treatment time, and it
is generally treated at a temperature of 0 C to 70 C. In
addition, it is preferably a temperature of 10 C to 60 C.
When sulfuric acid is used, the temperature of the aqueous
sulfuric acid solution may be a temperature of 0 C or
higher and 50 C or lower, and more preferably at a tempera-
ture of 0 C or higher and 30 C or lower.
[0052]
When the temperature of the polar solvent is within
the above-mentioned range, the color depth is within the
relatively stable range, and even if the temperature of the
polar solvent is slightly fluctuated, the color depth does
not so remarkably change. Accordingly, stable industrial
production can be done when the temperature of the polar
solvent is within the above-mentioned range. On the other
hand, if the temperature of the polar solvent is higher
than the above-mentioned range, lowering in physical
properties or extreme shrinkage of the aramid fibers
sometimes occurs. Also, by slightly varying the
temperature of the polar solvent, the color depth sometimes
markedly changes. It is thought that a high temperature
polar solvent causes marked change in molecular structure
of the aramid fibers.
[0053]
Also, a treatment time of the solvent treatment may
be optionally selected depending on a concentration and a
temperature of the polar solvent, and it is generally
treated with a time of about 0.1 seconds to 30 minutes.
Further, the treatment time of the solvent treatment is
preferably about 1 second to 5 minutes. Even if the
treatment time of the solvent treatment is about 0.1
seconds, the effects of the solvent treatment can be
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maintained. Thus, when the treatment time of the solvent
treatment is a time of about 0.1 seconds to 30 minutes,
even if the treatment time is slightly fluctuated, the
color depth is not so remarkably changed, and the fibers
can be dyed with a practical color depth.
[0054]
Thus, the treatment time of the solvent treatment is
preferably controlled within the predetermined range.
Accordingly, the aramid fibers treated by the polar solvent
are preferably washed quickly. Also, when the treatment is
carried out by sulfuric acid, the fibers are preferably
neutralized and washed quickly. Here, washing of the
aramid fibers may be carried out by washing with water or
washing with hot water, and for the purpose of removing the
vat dye or the sulfur dye which is attached onto the
surface of the aramid fibers with undying state, reduction
washing may be carried out.
[0055]
Here, when the aramid fibers are a fabric state, the
solvent treatment can be carried out by running to the
longitudinal direction. In this case, the running aramid
fiber fabrics are firstly immersed into a bath filled with
a treating solution containing a polar solvent. Subse-
quently, an excess treating solution is squeezed from the
aramid fiber fabrics by a squeezing means such as mangle,
etc. Next, the aramid fiber fabrics after the squeezing
are introduced in a continuous washing device while it is
running, and are subjected to washing, neutralization
washing or reduction washing. When these series of the
treatments are carried out continuously, the time from
immersion to washing, neutralization washing or reduction
washing can be controlled stably. According to the above,
the treatment time of the immersing treatment can be
maintained at a preferred timing and a uniform solvent
treatment can be carried out.
[0056]
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Incidentally, it is not clear about the action of
these solvent treatments, but it can be thought that, by
treating the aramid fibers with the polar solvent having a
concentration as mentioned above, intermolecular bonds of
the aramid fibers having a rigid molecular structure and
high crystallinity are partially relaxed to form many fine
voids. On the other hand, it can be also thought that
these polar solvents act on the dye molecules. According
to the above, the vat dye or the sulfur dye attached onto
the surface of the fibers by the dye providing step is
thought to be firmly dyed to the fine voids of the aramid
fibers by the solvent treatment step.
[0057]
In this first embodiment, the vat dye or the sulfur
dye having particularly good colorfastness to light is used
as mentioned above. According to the above, by carrying
out these series of the dyeing operation 1 (dye providing
step solvent treatment step), a dyed product of the
aramid fibers having a practical color depth, and having
good colorfastness, particularly good colorfastness to
light can be obtained. In particular, the dyeing method
according to the present invention is a specific dyeing
method which has never been in the conventional dyeing
methods, and it never uses the means of adsorption by
reduction which is the inherent dyeing mechanism of the vat
dye or the sulfur dye.
[0058]
Also, by repeating the above-mentioned dyeing
operation 1 (dye providing step solvent
treatment step) a
plural number of times, the color depth of the aramid
fibers can be improved. That is, to the aramid fibers dyed
by the dyeing operation 1 once according to the above-
mentioned method, a second time dyeing operation 1 is again
carried out, aramid fibers with a denser color can be
obtained. Further, the same dyeing operation 1 is repeated
again, the color depth can be more improved. According to
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the above, colorfastness of the dyed product dyed to a
dense color can be maintained with a good state.
(2) Second embodiment
The dyeing method according to this second embodiment
comprises a dye providing step in which the vat dye or the
sulfur dye is provided to the aramid fibers, a solvent
treatment step in which the aramid fibers are treated by a
treating solution containing a polar solvent, and a heat
treatment step in which the aramid fibers after the solvent
treatment step are subjected to the heat treatment. In
this second embodiment, these series of the steps are
generically called to as "dyeing operation 3". Incidental-
ly, the dyeing operation 3 (dye providing step -> solvent
treatment step -> heat treatment step) may be carried out
only once, or may be repeated a plural number of times,
depending on necessity. By repeating this dyeing operation
a plural number of times, aramid fibers with a denser color
can be obtained.
[0059]
A. Dye providing step
The dye providing step in this second embodiment is
carried out the same operations as those of the dye
providing step in the above-mentioned first embodiment.
[0060]
B. solvent treatment step
The solvent treatment step in this second embodiment
is carried out by the same operations as those of the
solvent treatment step in the above-mentioned first embodi-
ment. Incidentally, in this second embodiment, the aramid
fibers after the solvent treatment is introduced into the
subsequent heat treatment step without carrying out the
washing, neutralization washing or reduction washing.
[0061]
C. Heat treatment step
After the above-mentioned solvent treatment step, the
aramid fibers have already been dyed by the vat dye or the
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,
sulfur dye. Here, by carrying out the heat treatment, it
can be thought that dyeing of the vat dye or the sulfur dye
to the aramid fibers is more progressed so that the dyed
product becomes more firm. However, if sulfuric acid is
used as a polar solvent, fiber strength is markedly lowered
so that the heat treatment cannot be carried out.
[0062]
The heat treatment may be a dry heat treatment or a
wet heat treatment, and the dry heat treatment is generally
preferred. The heat treatment is preferably carried out at
a temperature of 50 C or higher and 200 C or lower. In the
heat treatment step, the aramid fibers are treated in the
state where the polar solvent is attached thereto, so if it
is higher than 200 C, lowering in physical properties of
the aramid fibers is considered to be caused so that it is
not preferred. Also, if it is treated at an extremely high
temperature, the vat dye or the sulfur dye is sometimes
decomposed and hue is markedly changed.
[0063]
On the other hand, the treatment time of the heat
treatment may be optionally selected depending on a kind or
a form of the aramid fibers, and a kind of the vat dye or
the sulfur dye to be used, and it does not become a parti-
cular problem and is generally carried out with a time of
about 30 second to 30 minutes. Further, the treatment time
of the heat treatment is preferably a time of about 30
second to 5 minutes. Even if the treatment time of the
heat treatment is a time of about 30 seconds, the effects
of the heat treatment can be maintained. Thus, if the
treatment time of the heat treatment is a time of about 30
second to 30 minutes, even when the treatment time is
slightly fluctuated, the color depth is not so remarkably
changed and the fibers can be dyed with a practical color
depth.
[0064]
Here, when the aramid fibers are a fabric state, the
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aramid fiber fabrics after the above-mentioned solvent
treatment step may be introduced into a continuous heat
treatment device while running the same to carry out the
heat treatment. When the series of the treatments from the
above-mentioned solvent treatment step to the heat treat-
ment step is carried out continuously, the treatment time
from immersing in the solvent to the heat treatment can be
controlled stably, the treatment times of the solvent
treatment and the heat treatment can be maintained to a
preferred timing, and uniform solvent treatment and heat
treatment can be carried out.
[0065]
Here, it is not clear about the action on the solvent
treatment and the heat treatment in combination, but it can
be thought that, by treating the aramid fibers with the
polar solvent having a concentration as mentioned above,
intermolecular bonds of the aramid fibers having a rigid
molecular structure and high crystallinity are partially
relaxed to form many fine voids. On the other hand, it can
be also thought that the action of the polar solvent on the
dye molecules is increased by the heat treatment.
According to the above, the vat dye or the sulfur dye
attached onto the aramid fibers by the solvent treatment
step is thought to be firmly dyed to the fine voids of the
aramid fibers by the heat treatment step after the solvent
treatment step.
[0066]
Next, the aramid fibers after the heat treatment step
are washed to remove the remaining polar solvent. The
washing may be carried out washing with water or washing
with hot water, and for the purpose of removing the vat dye
or the sulfur dye which is attached onto the surface of the
aramid fibers with undying state, reduction washing may be
carried out.
[0067]
In this second embodiment, as mentioned above, the
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vat dye or the sulfur dye which has particularly good
colorfastness to light is used. According to the above, by
carrying out these series of dyeing operation 3 (dye
providing step -> solvent treatment step -) heat treatment
step), a dyed product of the aramid fibers having a
practical color depth, and having good colorfastness,
particularly good colorfastness to light can be obtained.
In particular, the dyeing method according to the present
invention is a specific dyeing method which has never been
in the conventional dyeing methods, and it never uses the
means of adsorption by reduction which is the inherent
dyeing mechanism of the vat dye or the sulfur dye.
[0068]
Also, by repeating the above-mentioned dyeing
operation 3 (dye providing step solvent treatment step ->
heat treatment step) a plural number of times, the color
depth of the aramid fibers can be improved. That is, to
the aramid fibers dyed by the dyeing operation 3 once
according to the above-mentioned method, a second time
dyeing operation 3 is again carried out, aramid fibers with
a denser color can be obtained. Further, the same dyeing
operation 3 is repeated again, the color depth can be more
improved. According to the above, colorfastness of the
dyed product dyed to a dense color can be maintained with a
good state.
(3) Third embodiment
The dyeing method according to this third embodiment
has a pre-dyeing step which dyes the aramid fibers with a
dye other than the vat dye and the sulfur dye before the
dyeing operation 1 or the dyeing operation 3 explained in
the above-mentioned first embodiment or the above-mentioned
second embodiment. Incidentally, the above-mentioned
dyeing operation 1 or the dyeing operation 3 carried out
after the pre-dyeing step may be carried out once alone, or
may be repeated a plural number of times, depending on
necessity. By repeating the dyeing operation 1 or the
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dyeing operation 3 a plural number of times, aramid fibers
with a denser color can be obtained.
[0069]
Dl. Pre-dyeing step
In the dyeing method according to this third
embodiment, a pre-dyeing step is firstly carried out to the
undying aramid fibers. In this pre-dyeing step, a dyeing
solution containing a dye other than the vat dye and the
sulfur dye is used. The dyeing method of the pre-dyeing
step may be any method, dyeing mainly by dip dyeing is
carried out. A prescription of the dyeing solution to be
used in the pre-dyeing step may be the same as that of the
dye to be used in the ordinary dyeing method. Accordingly,
when the aramid fibers themselves are dyed, in the same
manner as in the conventional dyeing method of the aramid
fibers, a dyeing carrier, etc., may be used in combination.
On the other hand, when the aramid fibers are mixed with
the other chemical fibers or natural fibers to form a mixed
fiber, and the other fibers are to be dyed, the ordinary
dyeing method to the other fibers may be carried out.
[0070]
When the aramid fibers themselves are to be dyed in
the pre-dyeing step, any dyes may be used as a dye to be
used so long as it is a dye having an affinity to the
aramid fibers. For example, a disperse dye, a cationic dye
or an acid dye, etc., may be preferably used similarly as
in the dyeing of the usual polyamide fibers. In particular,
it is preferred to use a dye which has been selected as a
dye for the aramid fibers in the points of dyeing property
and colorfastness. On the other hand, when the aramid
fibers are mixed with the other chemical fibers or natural
fibers to form a mixed fiber, and the other fibers are to
be dyed, a dye suitable for the other fibers may be used.
For example, when the other fibers are polyester fibers, a
disperse dye is to be used. In addition, when the other
fibers are cotton or rayon fibers, a reactive dye or a
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Attorney Docket No. 30985-2
direct dye, etc., may be used.
[0071]
When the aramid fibers themselves are to be dyed, the
procedure can be carried out that the aramid fibers are
thrown into a dyeing solution containing a dye, a
temperature of the dyeing solution is raised to a dyeing
temperature, and the dyeing temperature is maintained at a
predetermined time. The dyeing temperature may be adjusted
depending on a kind or a form of the aramid fibers, and, a
kind and a color depth of the dye to be used, and it may be
generally a temperature of 80 C to 150 C. Also, the
temperature is preferably 100 C to 140 C, and more
preferably the temperature is 120 C to 135 C. If the
temperature exceeds 100 C in the dyeing, high temperature
and high pressure dyeing machine is used.
[0072]
When the aramid fibers themselves are to be dyed, if
the dyeing temperature is lower than 80 C, sufficient color
depth cannot be obtained, on the other hand, if the dyeing
temperature is higher than 150 C, it requires a device with
a specific specification as compared with the high
temperature and high pressure dyeing machine generally used,
and an energy cost is large.
[0073]
On the other hand, the dyeing time after temperature
raising may be optionally selected depending on a kind of
the dye, and a relation between the dyeing temperature and
the dyeing device and, for example, at a dyeing temperature
of 135 C using a disperse dye, it is preferably within the
range of 10 minutes to 90 minutes. Also, a bath ratio of
the dyeing is not particularly limited, for example, it may
be within the range of 1:5 to 1:100, etc. To the aramid
fibers after dyeing, washing by the ordinary method is
carried out. In addition, reduction washing may be carried
out in the same manner as in the dyeing step using a
conventional disperse dye.
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[0074]
In this third embodiment, the following mentioned
dyeing operation is subsequently carried out to the aramid
fibers carried out the above-mentioned pre-dyeing step.
[0075]
A. Dye providing step
The dye providing step in this third embodiment is
carried out the same operations as those of the dye
providing step in the above-mentioned first embodiment or
the above-mentioned second embodiment.
[0076]
B. Solvent treatment step
The solvent treatment step in this third embodiment
is carried out by the same operations as those of the
solvent treatment step in the above-mentioned first
embodiment or the above-mentioned second embodiment.
[0077]
C. Heat treatment step
In this third embodiment, the heat treatment step may
be carried out, if necessary. Incidentally, when the heat
treatment step is carried out in the third embodiment, the
same operations as those of the heat treatment step in the
above-mentioned second embodiment are carried out.
[0078]
In this third embodiment, as mentioned above, by
carrying out a series of the dyeing operation 1 or the
dyeing operation 3 after carrying out the pre-dyeing step,
a dyed product of the aramid fibers having a practical
color depth, and good colorfastness, in particular, good
colorfastness to light can be obtained.
[0079]
Further, in this third embodiment, by carrying out
the above-mentioned pre-dyeing step, the following effects
can be obtained. First, by carrying out the pre-dyeing
step using, for example, a disperse dye, a cationic dye or
an acid dye, to the aramid fibers themselves, fuzz at the
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surfaces of the aramid fibers themselves are more
sufficiently dyed, so that dyeing quality and color depth
are further improved. On the other hand, when the aramid
fibers are mixed with the other chemical fibers or natural
fibers to form a mixed fiber, by carrying out the pre-
dyeing step using a dye capable of dyeing these other
fibers, hue of the aramid fibers and that of the other
fibers can be unified, whereby the dyeing quality and the
color depth of the dyed product are further improved.
(4) Fourth embodiment
The dyeing method according to this fourth embodiment
has a post-dyeing step which dyes the aramid fibers with a
dye other than the vat dye and the sulfur dye after the
dyeing operation 1 or the dyeing operation 3 explained in
the above-mentioned first embodiment or the above-mentioned
second embodiment. Incidentally, the above-mentioned
dyeing operation 1 or the dyeing operation 3 carried out
before the post-dyeing step may be carried out once alone,
or may be repeated a plural number of times, depending on
necessity. By repeating the dyeing operation 1 or the
dyeing operation 3 a plural number of times, aramid fibers
with a denser color can be obtained.
[0080]
A. Dye providing step
The dye providing step in this fourth embodiment is
carried out the same operations as those of the dye
providing step in the above-mentioned first embodiment or
the above-mentioned second embodiment.
[0081]
B. Solvent treatment step
The solvent treatment step in this fourth embodiment
is carried out by the same operations as those of the
solvent treatment step in the above-mentioned first
embodiment or the above-mentioned second embodiment.
[0082]
C. Heat treatment step
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In this fourth embodiment, the heat treatment step
may be carried out, if necessary. Incidentally, when the
heat treatment step is carried out in the fourth embodiment,
the same operations as those of the heat treatment step in
the above-mentioned second embodiment are carried out.
[0083]
D2. Post-dyeing step
The post-dyeing step in this fourth embodiment is
carried out by the same operations as those of the pre-
dyeing step explained in the above-mentioned third
embodiment. However, the aramid fibers to be dyed in the
post-dyeing step have been already dyed by the vat dye or
the sulfur dye in the above-mentioned dyeing operation 1 or
the above-mentioned dyeing operation 3, which is different
from the pre-dyeing step of the above-mentioned third
embodiment.
[0084]
In this fourth embodiment, as mentioned above, by
carrying out the post-dyeing step after carrying out a
series of the dyeing operation 1 or the dyeing operation 3,
a dyed product of the aramid fibers having a practical
color depth, and good colorfastness, in particular, good
colorfastness to light can be obtained.
[0085]
Further, in this fourth embodiment, by carrying out
the above-mentioned post-dyeing step, the following effects
can be obtained. First, by carrying out the post-dyeing
step using, for example, a disperse dye, a cationic dye or
an acid dye, to the aramid fibers themselves, fuzz at the
surfaces of the aramid fibers themselves are more
sufficiently dyed, so that dyeing quality and color depth
are further improved. On the other hand, when the aramid
fibers are mixed with the other chemical fibers or natural
fibers to form a mixed fiber, by carrying out the post-
dyeing step using a dye capable of dyeing these other
fibers, hue of the aramid fibers and that of the other
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fibers can be unified, whereby the dyeing quality and the
color depth of the dyed product are further improved.
EXAMPLES
[0086]
In the following, based on the above-mentioned first
embodiment to fourth embodiment, to the respective para-
type aramid fibers, para-type copolymerized aramid fiber
and meta-type aramid fibers, dyeing of the following
respective Examples and Comparative Examples was carried
out.
[0087]
Example 1
In this Example 1, N-methyl-2-pyrrolidone was used as
a polar solvent, fabrics (hereinafter referred to as
"aramid fabrics") comprising the aramid fibers were dyed
based on the above-mentioned second embodiment. In this
Example 1, twilled fabrics (hereinafter referred to as
"para-type aramid fabrics") having an areal weight of 244
g/m2 and using No. 20 count two folded yarns comprising
100% by weight of para-type aramid fibers as warp yarns and
weft yarns, twilled fabrics (hereinafter referred to as
"para-type copolymerized aramid fabrics") having an areal
weight of 244 g/m2 and using No. 20 count two folded yarns
comprising 100% by weight of para-type copolymerized aramid
fibers as warp yarns and weft yarns, and twilled fabrics
(hereinafter referred to as "meta-type aramid fabrics")
having an areal weight of 200 g/m2 and using No. 40 count
two folded yarns comprising 100% by weight of meta-type
aramid fibers as warp yarns and weft yarns were used.
These aramid fabrics were used after desizing and degumming
by the ordinary method.
[0088]
A. Dye providing step
Dye providing procedure was carried out by a
continuous method using a mangle device for testing, and
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each of the aramid fabrics was subjected to pad and nip a
dyeing solution containing a vat dye to provide the vat dye
thereto. The pickup rates at this time were each 61% by
weight for the para-type aramid fabrics, 58% by weight for
the para-type copolymerized aramid fabrics, and 67% by
weight for the meta-type aramid fabrics.
[0089]
As the dyeing solution, 50 g/L of a vat dye was
dispersed in an unreduced state, and TAMANORI SA-25
(Arakawa Chemical Industries, Ltd.; hereinafter referred to
as "TAMANORI") was used as a migration preventive agent in
combination. The used dye was Mikethren Blue BC super-fine
(C.I. Vat Blue 6, vat dye available from DyStar Japan Ltd.).
[0090]
Drying was carried out by using a baking box device
for testing, and each of the aramid fabrics after providing
the dyeing solution was dried at 105 C for 5 minutes, to
adhere the vat dye onto the surfaces of the fibers of each
of the aramid fabrics. Each of the aramid fabrics after
drying was injected into a subsequent solvent treatment
step (N-methyl-2-pyrrolidone treatment step) as such
without carrying out washing or reduction washing.
[0091]
B. Solvent treatment step (N-methyl-2-pyrrolidone treatment
step)
N-methyl-2-pyrrolidone was used as a polar solvent,
and treatment was carried out by an aqueous solution with a
concentration of 60% by weight. For providing the treating
solution, a mangle device for testing was used, and each of
the aramid fabrics after the dye providing step was
subjected to the solvent treatment by a continuous method.
The treatment temperature at this time was 20 C. The
treatment was carried out by immersing the aramid fabrics
in the treating solution for 1 second and immediately
squeezed by the mangle. A pickup rate at this time was
each 59% by weight for the para-type aramid fabrics, 59% by
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weight for the para-type copolymerized aramid fabrics, and
62% by weight for the meta-type aramid fabrics.
[0092]
C. Heat treatment step
For the heat treatment, a baking box device for
testing was used, and each of the aramid fabrics after the
solvent treatment was carried out a dry heat treatment at
105 C for 5 minutes to adhere the vat dye onto each of the
aramid fabrics. Each of the aramid fabrics after the heat
treatment was dried after removing the remaining N-methy1-
2-pyrrolidone by washing with water and washing with hot
water.
[0093]
Next, reduction washing of each of the dyed aramid
fabrics after the heat treatment step was carried out. The
reduction washing was carried out to remove the undying vat
dye remaining at the surface of the fibers and to improve
colorfastness. The conditions of the reduction washing
were the same as those of the dyeing of the polyester
fibers by a disperse dye, and the treatment was carried out
by using 1 g/L of sodium dithionite as a reducing agent in
combination with 1 g/L of sodium hydroxide at 80 C for 1
minute, thereafter, washing with hot water and washing with
water were carried out and then the fabrics were dried to
obtain each of the aramid fabrics of Example 1 dyed to navy
blue and having a practical color depth.
[0094]
Comparative Example 1
Similarly to the above-mentioned Example 1, a mate-
rial in which the dye providing step alone of each of the
aramid fabrics has been carried out, and the solvent
treatment step and the heat treatment step have not been
carried out was made Comparative Example 1. More
specifically, the dye providing procedure was carried out
under the same conditions as those of the above-mentioned
Example 1, and reduction washing of each of the aramid
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fabrics after providing the vat dye was carried out. The
reduction washing was carried out under the same conditions
as those of the above-mentioned Example 1, thereafter,
washing with hot water and washing with water were carried
out and then the fabrics were dried to obtain each of the
aramid fabrics of Comparative Example 1.
[0095]
Each of the dyed aramid fabrics of Example 1 and
Comparative Example 1 which have been dyed as mentioned
above was evaluated as mentioned below.
[0096]
Color depth (total K/S value):
A surface color depth of each of the dyed aramid
fabrics was shown as a total K/S value. When the total K/S
value is larger, it means that the aramid fabrics are dyed
by a dense color. The total K/S means a total value of 16
K/S values at 16 wavelengths measured at 20 nm intervals in
the measured range of wavelengths of from 400 nm to 700 nm.
The K/S value can be obtained from a reflectance R at the
respective wavelengths from the following mentioned
Kubelka-Munk equation. Here, K represents an extinction
coefficient, and S represents a light scattering coeffi-
cient.
[0097]
K/S=(1-R)2/2R
Incidentally, the value of the reflectance R at the
respective wavelengths was measured by using a spectro-
photometer UV-3100 (manufactured by Shimadzu Corporation)
on which an integrating sphere has been mounted. With
regard to each of the aramid fabrics, the total K/S values
obtained by calculating according to the above formula were
shown in Table 1.
[0098]
Lightness (L* value)
A degree of the dense color of each of the dyed
aramid fabrics was evaluated by lightness (L* value) in the
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above-mentioned L*a*b* colorimetric system. The L* value
is shown in the range of 100 (white) to 0 (black), and the
L* value is smaller, then, it is evaluated to as a denser
color. Incidentally, the L* value was measured by using a
color difference meter CR-200 (manufactured by Minolta
Camera Co., Ltd.). The obtained L* values of each of the
aramid fabrics are shown in Table 1.
[0099]
Colorfastness:
Other than the above-mentioned color depth (total K/S
value) and lightness (L* value), colorfastness was
confirmed as a basic evaluation item of the dyed product.
In particular, colorfastness to light (JIS L0842) which is
assumed to be a problem in colorfastness of the aramid
fibers was evaluated. Colorfastness to light of the aramid
fibers is difficultly evaluated since fibers themselves
change yellowish brown in addition to discoloration of the
dye due to photoirradiation, so that it was evaluated as
mentioned below. Irradiation with fourth grade of blue
scale was carried out to each of the aramid fabrics, and
the change was judged by the grade of gray scale for
discoloration. Incidentally, judgment of the grade was, in
addition to the five grades from the first grade (failure)
to the fifth grade (good), intermediate evaluation of the
respective grades was also carried out. For example, an
evaluation between the third grade and the fourth grade was
mentioned as 3-4 grades. The evaluation results are shown
in Table 1.
[0100]
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[Table 1]
Each Aramid fabrics x Vat dye x N-methy1-2-
pyrrolidone
Example 1
Comparative Example 1
ColorColor- Color Color-
Light- Light-
Aramid depth fast- depth fast-
fabrics (Total ness
ness to (Total ness
ness to
(L* (L*
K/S light K/S light
value) value)
value) (grade) value)
(grade)
para-type 72.3 36.4 4 52.0 45.0 3-4
para-type
copoly- 85.0 31.1 4-5 80.7 36.8 4
meri zed
meta-type 50.3 35.2 3-4 6.6 76.9 2
[0101]
As can be seen from Table 1, in Example 1, either of
the respective aramid fabrics had the practical color depth
(total K/S value) and lightness (L* value), and each also
had good colorfastness to light. Further, whereas it is
not shown in Table 1, in each of the dyed aramid fabrics of
Example 1, the fabrics had maintained the practical
properties of high performance fibers without generating
color unevenness or dimensional change, or lowering in
physical properties markedly. On the other hand, in
Comparative Example 1, as compared with those of Example 1,
in either of the respective aramid fabrics, color depth,
lightness and colorfastness to light were inferior, in
particular, color depth, lightness and colorfastness to
light of the meta-type aramid fabrics were insufficient.
[0102]
Example 2
In this Example 2, aramid fabrics were dyed based on
the above-mentioned second embodiment and N-methy1-2-
pyrrolidone was used as a polar solvent. In this Example 2,
twilled fabrics (hereinafter referred to as "mixed spinning
aramid fabrics") having an areal weight of 160 g/m2 and
using No. 40 count two folded yarns in which 95% by weight
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of meta-type aramid fibers and 5% by weight of para-type
copolymerized aramid fibers had been mixed spinning as warp
yarns and weft yarns were used. This mixed spinning aramid
fabrics were used after desizing and degumming by the
ordinary method.
[0103]
A. Dye providing step
The same operations as in the above-mentioned Example
1 were carried out except for changing the dye to be used
to the sulfur dye mentioned below in the above-mentioned
Example 1. A pickup rate at this time was 80% by weight.
As the dyeing solution, 50 g/L of the sulfur dye was
dispersed in an unreduced state, and TAMANORI was used in
combination as a migration preventive agent. The sulfur
dye used was Asathio Blue RC200 (C.I. Sulphur Blue 7,
sulfur dye available from Asahi Kagaku Kogyo Co., Ltd.).
[0104]
Drying was carried out in the same manner as in the
above-mentioned Example 1, and the mixed spinning aramid
fabrics after providing the dyeing solution thereto was
dried at 105 C for 5 minutes to adhere the sulfur dye on
the surfaces of the fibers of the mixed spinning aramid
fabrics. The mixed spinning aramid fabrics after drying
was injected into the subsequent solvent treatment step (N-
methy1-2-pyrrolidone treatment step) as such without
carrying out washing or reduction washing.
[0105]
B. Solvent treatment step (N-methyl-2-pyrrolidone treatment
step)
In this Example 2, N-methyl-2-pyrrolidone which is
the same as in the above-mentioned Example 1 was used as a
polar solvent, but the treatment was carried out with a
concentration of 100% by weight. For providing the
treating solution, a mangle device for testing was used,
and the mixed spinning aramid fabrics after the dye
providing step were subjected to the solvent treatment by a
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continuous method. The treatment temperature at this time
was 50 C.
The treatment was carried out by immersing the mixed
spinning aramid fabrics into the treating solution for 1
second and then immediately squeezed by the mangle. A
pickup rate at this time was 88% by weight.
[0106]
C. Heat treatment step
The heat treatment was carried out in the same manner
as in the above-mentioned Example 1, and by using a baking
box device for testing, dry heat treatment of the mixed
spinning aramid fabrics after the solvent treatment was
carried out at 105 C for 5 minutes to adhere the sulfur dye
onto the mixed spinning aramid fabrics. The mixed spinning
aramid fabrics after the heat treatment were dried after
removing the remaining N-methyl-2-pyrrolidone by washing
with hot water and washing with water, to obtain mixed
spinning aramid fabrics of Example 2 dyed to navy blue and
having a practical color depth.
[0107]
Comparative Example 2
Similarly to the above-mentioned Example 2, a
material in which the dye providing step alone of each of
the aramid fabrics has been carried out, and the solvent
treatment step and the heat treatment step have not been
carried out was made Comparative Example 2. More
specifically, the mixed spinning aramid fabrics which have
been carried out the dye providing step under the same
conditions as those of the above-mentioned Example 2 to
provide the sulfur dye were subjected to washing with hot
water and washing with water, and drying to obtain mixed
spinning aramid fabrics of Comparative Example 2 which were
dyed to navy blue.
[0108]
The dyed mixed spinning aramid fabrics of Example 2
and Comparative Example 2 which had been dyed as mentioned
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above were evaluated in the same manner as in the above-
mentioned Example 1. The evaluation results of the total
K/S value which evaluates the color depth, lightness (L*
value) which evaluates the degree of a dark color and
colorfastness to light are shown in Table 2.
[0109]
[Table 2]
Mixed spinning aramid fabrics x Sulfur dye x N-
methyl-2-pyrrolidone
Example 2 Comparative Example 2
ColorColor- Color Color-
Aramid depth Light-
fast- depth Light-
fast-.
fabrics (Total ness
ness to (Total ness
ness to
(L* (L*
K/S light K/S light
value) value)
value) (grade) value) (grade)
Mixed
108.2 27.1 3-4 39.8 44.0 3
spinning
[0110]
As can be seen from Table 2, in Example 2, mixed
spinning aramid fabrics having a practical color depth
(total K/S value) and lightness (L* value) could be
obtained. Also, the mixed spinning aramid fabrics of
Example 2 have good colorfastness to light. Further,
whereas it is not shown in Table 2, in the dyed mixed
spinning aramid fabrics of Example 2, the fabrics had
maintained the practical properties of high performance
fibers without generating color unevenness or dimensional
change, or lowering in physical properties markedly. On
the other hand, in Comparative Example 2, as compared with
those of Example 2, both of color depth and lightness were
markedly inferior, and colorfastness to light was also low
so that no practically dyed product was obtained.
[0111]
Example 3
In this Example 3, aramid fabrics were dyed based on
the above-mentioned second embodiment and N-methyl-2-
pyrrolidone was used as a polar solvent. In this Example 3,
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to each of the dyed aramid fabrics obtained in the above-
mentioned Example 1 were repeated the same dyeing opera-
tions as the above-mentioned Example 1 a plural number of
times. More specifically, the above-mentioned Example 1
was made the dyeing operation once, and the dyeing opera-
tion in which the dye providing step, the solvent treatment
step and the heat treatment step had been combined was
further repeated to carry out a total of 3 times, a total
of 5 times and a total of 7 times of the dyeing operations.
However, the reduction washing was carried out at after the
final dyeing operation alone.
[0112]
Each of the dyed aramid fabrics of Example 3 which
had been dyed as mentioned above were evaluated in the same
manner as in the above-mentioned Example 1. The evaluation
results of the total K/S value which evaluates the color
depth, lightness (L* value) which evaluates the degree of a
dark color and colorfastness to light are shown in Table 3.
[0113]
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[Table 3]
Each Aramid fabrics x Vat dye x N-methyl-2-
pyrrolidone
Color
Dyeing Color-
depth Light-
Aramid opera- fastness
(Total ness (L*
fabrics tion to light
K/S value)
(times) (grade)
value)
Example
1 72.3 36.4 4
1
3 107.3 31.1 4
para-type
Example
119.9 29.3 4-5
3
7 123.9 29.0 5
_.
Example
1 85.0 31.1 4-5
1
para-type
copoly-
3 134.9 26.7 4-5
Example
merized 5 158.9 24.5 5
3
7 173.5 23.6 5
Example
1 50.3 35.2 3-4
1
3 104.8 29.5 4
meta-type
Example
5 134.5 25.4 4-5
3
7 167.5 23.8 5
[0114]
As can be seen from Table 3, in each of the aramid
fabrics, as compared with Example 1 in which the dyeing
operation is once, in Example 3, as a number of the dyeing
operation increases, the color depth (total K/S value) is
markedly improved, and lightness (L* value) becomes small
as substantially around 30 or lower, and each of the aramid
fabrics with a very dark color can be obtained. Each of
these aramid fabrics with a very dark color have had good
colorfastness to light as shown in Table 3. Further,
whereas it is not shown in Table 3, in each of the dyed
aramid fabrics of Example 3, the fabrics had maintained the
practical properties of high performance fibers without
generating color unevenness or dimensional change, or
lowering in physical properties markedly.
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[0115]
Example 4
In this Example 4, aramid fabrics were dyed based on
the above-mentioned second embodiment and N-methy1-2-
pyrrolidone was used as a polar solvent. In this Example 4,
to each of the aramid fabrics which are similar to the
above-mentioned Example 1 were repeated the dyeing
operations by the vat dye with a plural number of times in
the same manner as in the above-mentioned Example 3.
However, the used vat dye was Indanthren Brilliant Pink R
(C.I. Vat Red 1, vat dye available from DyStar Japan Ltd.).
More specifically, the above-mentioned Example 1 was made
the dyeing operation once, and the dyeing operation in
which the dye providing step, the solvent treatment step
and the heat treatment step had been combined was further
repeated to carry out a total of 2 times and a total of 3
times of the dyeing operations. However, the reduction
washing was carried out at after the final dyeing operation
alone.
[0116]
Each of the dyed aramid fabrics of Example 4 which
had been dyed as mentioned above were evaluated in the same
manner as in the above-mentioned Example 1. The evaluation
results of the total K/S value which evaluates the color
depth, lightness (L* value) which evaluates the degree of a
dark color and colorfastness to light are shown in Table 4.
[0117]
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[Table 4]
Each Aramid fabrics x Vat dye x N-methy1-2-
pyrrolidone
Color
Dyeing
depth Light- Colorfastness
Aramid opera-
(Total ness (L* to light
fabrics tion
(times) K/S value) (grade)
value)
1 44.2 54.8 4
para-
2 57.9 50.0 4-5
type
3 62.2 47.6 5
para- 1 53.4 48.7 4-5
Example type
2 80.1 43.8 4-5
4 copoly-
merized 3 92.1 41.9 5
1 39.6 49.9 3-4
meta-
2 66.3 44.9 4
type
3 78.2 42.5 5
[0118]
As can be seen from Table 4, in each of the aramid
fabrics, as compared with the case where the dyeing
operation is once, as a number of the dyeing operation
increases, the color depth (total K/S value) is markedly
improved, and each of the aramid fabrics with a dark color
can be obtained. Whereas the lightness (L* value) is
larger than 38, this is because the dye used is "Pink R".
This Example 4 is a prescription to dye a vivid red, which
is not a prescription to obtain a dark color such as navy
blue and black. On the other hand, each of the aramid
fabrics has good colorfastness to light as shown in Table 4.
Further, whereas it is not shown in Table 4, in each of the
dyed aramid fabrics of Example 4, the fabrics had
maintained the practical properties of high performance
fibers without generating color unevenness or dimensional
change, or lowering in physical properties markedly.
[0119]
Example 5
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In this Example 5, aramid fabrics were dyed according
to the above-mentioned fourth embodiment (dyeing by a vat
dye post-dyeing by a disperse dye) and N-methy1-2-
pyrrolidone was used as a polar solvent. In this Example 5,
to each of the dyed aramid fabrics by the vat dye obtained
in the above-mentioned Example 1, a post-dyeing step using
a disperse dye was carried out subsequently.
[0120]
D2. Post-dyeing step by disperse dye
Dyeing was carried out by the immersion dyeing method
using a disperse dye, and each of the aramid fabrics after
dyed by the vat dye obtained in the above-mentioned Example
1 was dyed by using a high temperature and high pressure
dyeing tester MINI-COLOR (manufactured by TEXAM Giken Co.,
Ltd.) without reduction washing. As the dyeing solution,
5% owf of Dianix Blue FBL-E (C.I. Disperse Blue 56,
disperse dye available from DyStar Japan Ltd.) was used,
and an acetic acid/sodium acetate series buffer with a pH 5
was used in combination.
[0121]
As a dyeing method, a high temperature and high
pressure dyeing was carried out by making a bath ratio of
1:100, and under the conditions at 135 C for 60 minutes.
Reduction washing was carried out to each of the aramid
fabrics after the dyeing in the same manner as in the
dyeing of ordinary polyester fibers by a disperse dye. The
reduction washing was carried out under the conditions of
using 1 g/L of sodium dithionite as a reducing agent in
combination with 1 g/L of sodium hydroxide at 80 C for 1
minute, thereafter, washing with hot water and washing with
water were carried out and then the fabrics were dried to
obtain each of the aramid fabrics of Example 5 dyed to navy
blue which is a very dark color.
[0122]
Comparative Example 3
Similarly to the above-mentioned Example 5, a
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material in which each of the aramid fabrics had been
carried out dyeing by the disperse dye alone was made
Comparative Example 3. More specifically, none of the
dyeing operations comprising the dye providing step, the
solvent treatment step or the heat treatment step according
to the present invention was carried out, but the dyeing
step with a disperse dye alone which is the same as that of
the above-mentioned Example 5 was carried out, thereafter,
reduction washing, washing with hot water and washing with
water were carried out in the same manner as in Example 5,
and the fabrics were dried to obtain each of the aramid
fabrics of Comparative Example 3 dyed to navy blue.
[0123]
Comparative Example 4
Also, similarly to the above-mentioned Example 5, a
material in which each of the aramid fabrics had been
carried out the solvent treatment step, the heat treatment
step and the dyeing step by a disperse dye alone was made
Comparative Example 4. More specifically, the solvent
treatment step and the heat treatment step alone were
carried out without carrying out the dye providing step
which is to provide a vat dye, and then, the dyeing step
with a disperse dye which is the same as in the above-
mentioned Example 5 was carried out, thereafter, reduction
washing, washing with hot water and washing with water were
carried out in the same manner as in Example 5, and the
fabrics were dried to obtain each of the aramid fabrics of
Comparative Example 4 dyed to navy blue.
[0124]
Each of the dyed aramid fabrics of Example 5,
Comparative Example 3 and Comparative Example 4 which had
been dyed as mentioned above were evaluated in the same
manner as in the above-mentioned Example 1. The evaluation
results of the total K/S value which evaluates the color
depth, lightness (L* value) which evaluates the degree of a
dark color and colorfastness to light are shown in Table 5.
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[0125]
[Table 5]
Each Aramid fabrics x Vat dye+Disperse dye x N-
methyl-2-pyrrolidone
Color
Light-
depth
Colorfastness
Aramid ness
Dye (Total to light
fabrics (L*
K/S (grade)
value) value)
Vat +
Example 5 110.2 29.0 4-5
Disperse
Example 1 Vat 72.3 36.4 4
para-
Comparative
type Disperse 67.8 40.8 3-4
example 3
Comparative
Disperse 71.7 39.4 3-4
example 4
Vat +
Example 5 124.6 27.7 5
Disperse
para-
Example 1 Vat 85.0 31.1 4-5
type
copoly- Comparative
Disperse 31.3 55.1 3-4
merized example 3
Comparative
Disperse 50.6 43.4 4
example 4
Vat +
Example 5 103.2 29.8 4
Disperse
Example 1 Vat 50.3 35.2 3-4
meta-
Comparative
type Disperse 17.5 56.9 2
example 3
Comparative
Disperse 49.4 41.2 3
example 4
[0126]
As can be seen from Table 5, as compared with Example
1 dyed by the vat dye alone, in Example 5 in which the
fibers are further dyed by a disperse dye, each of the
aramid fabrics markedly improved in color depth (total K/S
value), having small lightness (L* value) of 30 or less,
with a very dark color can be obtained. Each of the aramid
fabrics with the very dark color has better colorfastness
to light than that of Example 1 as shown in Table 5. Also,
in each of the aramid fabrics of this Example 5, fuzz at
the surfaces of the fabrics have been dyed by both of the
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vat dye and the disperse dye to a very dark color, and
surface quality of the fabrics has been more improved.
Further, whereas it is not shown in Table 5, in each of the
dyed aramid fabrics of Example 5, the fabrics had
maintained the practical properties of high performance
fibers without generating color unevenness or dimensional
change, or lowering in physical properties markedly.
[0127]
On the other hand, in Comparative Example 3, as
compared with those of Example 5, color depth and lightness
were inferior thereto in either of the respective aramid
fabrics. In addition, these respective aramid fabrics were
dyed only by the disperse dye, and colorfastness to light
was insufficient as compared with those of Example 5 and
Example 1. Also, in Comparative Example 4, by the effects
of the solvent treatment, the color depth and lightness by
the disperse dye are improved than those of Comparative
Example 3. However, the respective aramid fabrics of
Comparative Example 4 are inferior to those of Example 5 in
both of the color depth and lightness. Moreover, these
respective aramid fabrics of Comparative Example 4 were
dyed only by the disperse dye, and colorfastness to light
was insufficient as compared with those of Example 5.
[0128]
Example 6
In this Example 6, aramid fabrics were dyed based on
the above-mentioned first embodiment and using sulfuric
acid as a polar solvent. In this Example 6, the same mixed
spinning aramid fabrics as those of the above-mentioned
Example 2 were used. This mixed spinning aramid fabrics
were used after desizing and degumming by the ordinary
method.
[0129]
A. Dye providing step
In this Example 6, the vat dye "Mikethren Blue BC
super-fine" which is the same as used in the above-
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mentioned Example 1, or the vat dye "Indanthren Brilliant
Pink R" which is the same as used in the above-mentioned
Example 4 was used. The operations in the dye providing
step were carried out in the same manner as in the above-
mentioned Example 1. A pickup rate at this time was 80% by
weight.
[0130]
Drying was carried out in the same manner as in the
above-mentioned Example 1, and the mixed spinning aramid
fabrics after providing the dyeing solution was dried at
105 C for 5 minutes to adhere the vat dye onto the surfaces
of the fibers of the mixed spinning aramid fabrics. The
mixed spinning aramid fabrics after drying was injected
into the subsequent solvent treatment step (sulfuric acid
treatment step) as such without carrying out washing or
reduction washing.
[0131]
B. Solvent treatment step (sulfuric acid treatment step)
The sulfuric acid treatment was carried out by the
continuous method, using a mangle device for testing, and
the sulfuric acid treatment was carried out to the mixed
spinning aramid fabrics after the dye providing step. A
concentration of the used aqueous sulfuric acid solution
was 77% by weight, and a treatment temperature was 20 C.
After immersion, the fabrics were squeezed by the mangle to
make a pickup rate 156% by weight, and then, immediately
washed with water and neutralized by an aqueous sodium
carbonate solution, and washed with water. An immersion
time in the aqueous sulfuric acid solution was 30 seconds.
The mixed spinning aramid fabrics after the solvent
treatment step was sufficiently washed with water and then
dried.
[0132]
Next, reduction washing was carried out to the dyed
mixed spinning aramid fabrics after the sulfuric acid
treatment. The reduction washing was carried out under the
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same conditions as those of the above-mentioned Example 1,
thereafter, washing with hot water and washing with water
were carried out and dried to obtain mixed spinning aramid
fabrics of Example 6 having a practical color depth.
[0133]
Comparative Example 5
Similarly to the above-mentioned Example 6, the dye
providing step alone was carried out to the mixed spinning
aramid fabrics without carrying out the sulfuric acid
treatment, which was made Comparative Example 5. More
specifically, reduction washing was carried out to the
mixed spinning aramid fabrics which had been carried out
the dye providing step under the same conditions as those
of the above-mentioned Example 1 to provide the vat dye.
The reduction washing was carried out under the same
conditions as those of the above-mentioned Example 1,
thereafter, washing with hot water and washing with water
were carried out and then the fabrics were dried to obtain
mixed spinning aramid fabrics of Comparative Example 5.
[0134]
The dyed mixed spinning aramid fabrics of Example 6
and Comparative Example 5 which had been dyed as mentioned
above were evaluated in the same manner as in the above-
mentioned Example 1. The evaluation results of the total
K/S value which evaluates the color depth, lightness (L*
value) which evaluates the degree of a dark color and
colorfastness to light are shown in Table 6.
[0135]
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[Table 6]
Mixed spinning Aramid fabrics x Vat dye x Sulfuric
acid
Example 6
Comparative Example 5
ColorColor- Color Color-
Light- Light-
Vat dye depth
ness fast- depth
ness fast-
(Total (L* (L* ness to (Total ness
to
K/S light K/S light
value) value)
value) (grade) value) (grade)
Blue BC 86.6 31.0 4 43.3 40.8 3
Pink R 62.3 45.7 4-5 46.0 49.2 3-4
[0136]
As can be seen from Table 6, in Example 6, the mixed
spinning aramid fabrics having a practical color depth
(total K/S value) and lightness (L* value) can be obtained
by using the vat dye "Blue BC". On the other hand, in the
vat dye "Pink R" of Example 6, it is a prescription for
dyeing a vivid red in the same manner as in the above-
mentioned Example 4, so that lightness (L* value) does not
show a small value. However, in the vat dye "Pink R", the
mixed spinning aramid fabrics having a practical color
depth (total K/S value) can be obtained. Also, the mixed
spinning aramid fabrics of Example 6 each have good
colorfastness to light. Further, whereas it is not shown
in Table 6, in the dyed mixed spinning.aramid fabrics of
Example 6, the fabrics had maintained the practical
properties of high performance fibers without generating
color unevenness or dimensional change, or lowering in
physical properties markedly. On the other hand, in
Comparative Example 5, as compared with Example 6, both of
the color depth and colorfastness to light were inferior,
and no practically dyed product can be obtained.
[0137]
Example 7
In this Example 7, aramid fabrics were dyed based on
the above-mentioned first embodiment and sulfuric acid was
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used as a polar solvent. In this Example 7, among the dyed
mixed spinning aramid fabrics obtained in the above-
mentioned Example 6, to the mixed spinning aramid fabrics
dyed by the vat dye "Mikethren Blue BC super-fine" were
repeated the dyeing operation which is the same as those of
the above-mentioned Example 6 with a plural number of times.
More specifically, the above-mentioned Example 6 was made
the dyeing operation once, and the dyeing operation in
which the dye providing step and the solvent treatment step
(sulfuric acid treatment step) had been combined was
further repeated to carry out a total of 3 times, a total
of 5 times and a total of 7 times of the dyeing operations.
However, the reduction washing was carried out at after the
final dyeing operation alone.
[0138]
The dyed mixed spinning aramid fabrics of Example 7
which had been dyed as mentioned above were evaluated in
the same manner as in the above-mentioned Example 1. The
evaluation results of the total K/S value which evaluates
the color depth, lightness (L* value) which evaluates the
degree of a dark color and colorfastness to light are shown
in Table 7.
[0139]
[Table 7]
Mixed spinning Aramid fabrics x Vat
dye x Sulfuric acid
Color
Dyeing Colorfas
depth Light-
opera- tness to
Vat dye (Total ness (L*
tion light
K/S value)
(times) (grade)
value)
Example 1 86.6 31.0 4
6
3
Blue BC 142.6 24.1 4-5
Example
169.3 21.8 5
7
7 199.6 20.3 5
[0140]
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As can be seen from Table 7, as compared with Example
6 in which the dyeing operation is once, in Example 7, as a
number of the dyeing operation increases, the color depth
(total K/S value) is markedly improved, and lightness (L*
value) becomes small as 25 or less, and the mixed spinning
aramid fabrics with a very dark color can be obtained.
These mixed spinning aramid fabrics with a very dark
color have had good colorfastness to light as shown in
Table 7. Further, whereas it is not shown in Table 7, in
the dyed mixed spinning aramid fabrics of Example 7, the
fabrics had maintained the practical properties of high
performance fibers without generating color unevenness or
dimensional change, or lowering in physical properties
markedly.
[0141]
Example 8
In this Example 8, aramid fabrics were dyed based on
the above-mentioned first embodiment and sulfuric acid was
used as a polar solvent. In this Example 8, the dyeing
operation by the sulfur dye was carried out to the same
mixed spinning aramid fabrics as in Example 6. The mixed
spinning aramid fabrics were used after desizing and
degumming by the ordinary method in the same manner as in
the above-mentioned Example 6.
[0142]
A. Dye providing step
In this Example 8, similarly to the above-mentioned
Example 6, the same operations as in the above-mentioned
Example 6 were carried out except for changing the dye to
be used to the following mentioned sulfur dye. A pickup
rate at this time was 80% by weight. As the dyeing
solution, 50 g/L of the sulfur dye was dispersed in an
unreduced state, and TAMANORI was used as a migration
preventive agent in combination. The sulfur dyes used were
Asathiosol Yellow S-RR (C.I. No. unknown, sulfur dye
available from Asahi Kagaku Kogyo Co., Ltd.), Asathiosol
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Bordeaux S-3B (C.I. Sulphur Red 6, sulfur dye available
from Asahi Kagaku Kogyo Co., Ltd.), Asathiosol Blue RC200
(C.I. Sulphur Blue 7, sulfur dye available from Asahi
Kagaku Kogyo Co., Ltd.), and Asathiosol Indigo Green S-BG
(C.I. Sulphur Blue 15, sulfur dye available from Asahi
Kagaku Kogyo Co., Ltd.).
[0143]
Drying was carried out in the same manner as in the
above-mentioned Example 6, and the mixed spinning aramid
fabrics after providing the dyeing solution thereto was
dried at 105 C for 5 minutes to adhere the sulfur dye onto
the surfaces of the fibers of the mixed spinning aramid
fabrics. The mixed spinning aramid fabrics after drying
was injected into the subsequent solvent treatment step
(sulfuric acid treatment step) as such without carrying out
washing or reduction washing.
[0144]
B. Solvent treatment step (sulfuric acid treatment step)
In this Example 8, the sulfuric acid treatment was
carried out to the mixed spinning aramid fabrics after the
dye providing step in the same manner as in the above-
mentioned Example 6. A concentration of the used aqueous
sulfuric acid solution was 77% by weight, a treatment
temperature was 20 C and an immersing time was 30 seconds.
A pickup rate at this time was 156% by weight, and washing
with water, neutralization and washing with water were
carried out in the same manner as in the above-mentioned
Example 6, and the fabrics were dried to obtain mixed
spinning aramid fabrics of Example 8 having a practical
color depth.
[0145]
Comparative Example 6
Similarly to the above-mentioned Example 8, the dye
providing step alone was carried out to the mixed spinning
aramid fabrics without carrying out the sulfuric acid
treatment which was made Comparative Example 6. More
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specifically, the mixed spinning aramid fabrics carrying
out the dye providing step in the same conditions as those
of the above-mentioned Example 8 to provide the sulfur dye
was washed with water and dried to obtain mixed spinning
aramid fabrics of Comparative Example 6.
[0146]
The dyed mixed spinning aramid fabrics of Example 8
and Comparative Example 6 which had been dyed as mentioned
above were evaluated in the same manner as in the above-
mentioned Example 1. However, lightness (L* value) was not
measured. The evaluation results of the total K/S value
which evaluates the color depth and colorfastness to light
are shown in Table 8.
[0147]
[Table 8]
Mixed spinning Aramid fabrics x Sulfur dye x Sulfuric
acid
Example 8
Comparative Example 6
ColorColor- Color Color-
Sulfur depth Light-
fast- depth Light-
fast-
dye (Total ness
ness to (Total ness
(L* (L* ness to
K/S light K/S light
value) value)
value) (grade) value)
(grade)
Yellow
10.3 3-4 7.0 3
S-RR
Bordeaux
19.9 3 5.6 2-3
S-3B
Blue
30.3 4 26.7 3-4
RC200
GS-BG reen
16.6 3 5.4 2-3
[0148]
As can be seen from Table 8, in Example 8, the mixed
spinning aramid fabrics having a practical color depth
(total K/S value) can be obtained. Also, each of the mixed
spinning aramid fabrics of Example 8 has good colorfastness
to light. Further, whereas it is not shown in Table 8, in
the dyed mixed spinning aramid fabrics of Example 8, the
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fabrics had maintained the practical properties of high
performance fibers without generating color unevenness or
dimensional change, or lowering in physical properties
markedly. On the other hand, in Comparative Example 6, as
compared with those of Example 8, both of the color depth
and colorfastness to light are inferior, and no practically
dyed product can be obtained.
[0149]
Example 9
In this Example 9, aramid fabrics were dyed based on
the above-mentioned first embodiment and sulfuric acid was
used as a polar solvent. In this Example 9, as the aramid
fibers mainly comprising the para-type aramid fibers,
twilled fabrics (hereinafter referred to as "para-type
single yarn aramid fabrics") having an areal weight of 144
g/m2 and using No. 20 count single yarn comprising 100% by
weight of para-type aramid fibers as warp yarns and weft
yarns were used. The para-type single yarn aramid fabrics
were used after desizing and degumming by the ordinary
method.
[0150]
In this Example 9, the dye providing step and the
solvent treatment step (sulfuric acid treatment step) were
carried out in the same operation conditions and the same
dyes used in the above-mentioned Example 6. A pickup rate
at the dye providing step at this time was 61% by weight,
and a pickup rate at the solvent treatment step was 126% by
weight. After carrying out the dyeing operation by the vat
dye according to the above, reduction washing was carried
out in the same manner as in the above-mentioned Example 1
to obtain para-type single yarn aramid fabrics of Example 9
having a practical color depth.
[0151]
Comparative Example 7
Similarly to the above-mentioned Example 9, the dye
providing step alone was carried out to the para-type
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single yarn aramid fabrics without carrying out the
sulfuric acid treatment, which was made Comparative Example
7. More specifically, reduction washing was carried out
with the same conditions as in Example 1 to the para-type
single yarn aramid fabrics which had been carried out the
dye providing step with the same conditions as in the
above-mentioned Example 9 to provide the vat dye. There-
after, washing with hot water and washing with water were
carried out and the fabrics were dried to obtain para-type
single yarn aramid fabrics of Comparative Example 7.
[0152]
The dyed para-type single yarn aramid fabrics of
Example 9 and Comparative Example 7 which had been dyed as
mentioned above were evaluated in the same manner as in the
above-mentioned Example 1. However, lightness (L* value)
was not measured. The evaluation results of the total K/S
value which evaluates the color depth and colorfastness to
light are shown in Table 9.
[0153]
[Table 9]
para-type single yarn Aramid fabrics x Vat
dye x Sulfuric acid
Example 9 Comparative
Example 7
ColorColor- Color Color-
Vat depth Light-
fast- depth Light-
fast-
dye (Total ness
ness to (Total ness
(L* (L*
ness to
K/S light K/S light
value) value)
value) (grade) value) (grade)
Blue
50.0 3-4 30.4 3
BC
Pink R 47.0 4-5 31.7 4
[0154]
As can be seen from Table 9, in Example 9, the para-
type single yarn aramid fabrics having a practical color
depth (total K/S value) can be obtained. Also, each of the
para-type single yarn aramid fabrics of Example 9 has good
colorfastness to light. Further, whereas it is not shown
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in Table 9, in the para-type single yarn aramid fabrics of
Example 9, the fabrics had maintained the practical
properties of high performance fibers without generating
color unevenness or dimensional change, or lowering in
physical properties markedly. On the other hand, in
Comparative Example 7, as compared with Example 9, both of
the color depth and colorfastness to light are inferior,
and no practically dyed product can be obtained.
[0155]
Example 10
In this Example 10, aramid fabrics were dyed based on
the above-mentioned first embodiment and sulfuric acid was
used as a polar solvent. In this Example 10, among the
dyed para-type single yarn aramid fabrics obtained in the
above-mentioned Example 9, the same dyeing operation which
is the same as in the above-mentioned Example 9 was
repeated to the para-type single yarn aramid fabrics dyed
by the vat dye "Mikethren Blue BC super-fine" with a plural
number of times. More specifically, the above-mentioned
Example 9 was made the dyeing operation once, and the
dyeing operation in which the dye providing step and the
solvent treatment step (sulfuric acid treatment step) had
been combined was further repeated to carry out a total of
3 times, a total of 5 times and a total of 7 times of the
dyeing operations. However, the reduction washing was
carried out at after the final dyeing operation alone.
[0156]
The dyed para-type single yarn aramid fabrics of
Example 10 which had been dyed as mentioned above were
evaluated in the same manner as in the above-mentioned
Example 1. However, lightness (L* value) was not measured.
The evaluation results of the total K/S value which
evaluates the color depth and colorfastness to light are
shown in Table 10.
[0157]
[Table 10]
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para-type single yarn Aramid fabrics x Vat
dye x Sulfuric acid
Color
Dyeing Colorfas
depth Light-
opera- tness to
Vat dye(Total ness (L*
tion light
K/S value)
(times) (grade)
value)
Example 1 50.0 3-4
9
3 70.6 4
Blue BC
Example
75.9 5
7 88.1
[0158]
As can be seen from Table 10, as compared with
Example 9 in which the dyeing operation is once, in Example
10, as a number of the dyeing operation increases, the
color depth (total K/S value) is markedly improved, and the
aramid fabrics with a very dark color can be obtained.
These para-type single yarn aramid fabrics with a very dark
color have had good colorfastness to light as shown in
Table 10. Further, whereas it is not shown in Table 10, in
the dyed para-type single yarn aramid fabrics of Example 10,
the fabrics had maintained the practical properties of high
performance fibers without generating color unevenness or
dimensional change, or lowering in physical properties
markedly.
[0159]
Example 11
In this Example 11, aramid fabrics were dyed based on
the above-mentioned fourth embodiment and sulfuric acid was
used as a polar solvent. In this Example 11, the same
mixed spinning aramid fabrics as those used in the above-
mentioned Example 6 was used. The mixed spinning aramid
fabrics were used after desizing and degumming by the
ordinary method.
[0160]
A. Dye providing step
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In this Example 11, the same operations were carried
out as in the above-mentioned Example 1 except for using 60
g/L of Mikethren Grey M super-fine (C.I. Vat Black 8, vat
dye available from DyStar Japan Ltd.) as the vat dye. A
pickup rate at this time was 80% by weight.
[0161]
Drying was carried out in the same manner as in the
above-mentioned Example 1, and the mixed spinning aramid
fabrics after providing the dyeing solution was dried at
105 C for 5 minutes to adhere the vat dye onto the surfaces
of the fibers of the mixed spinning aramid fabrics. The
mixed spinning aramid fabrics after drying was injected
into the subsequent solvent treatment step (sulfuric acid
treatment step) as such without carrying out washing or
reduction washing.
[0162]
B. Solvent treatment step (Sulfuric acid treatment step)
The sulfuric acid treatment was carried out by the
continuous method, using a mangle device for testing, and
the sulfuric acid treatment was carried out to the mixed
spinning aramid fabrics after the dye providing step. A
concentration of the used aqueous sulfuric acid solution
was 80% by weight, and a treatment temperature was 20 C.
After immersion, the fabrics were squeezed by the mangle to
make a pickup rate 80% by weight, and then, immediately
washed with water and neutralized by an aqueous sodium
carbonate solution, and washed with water. An immersion
time in the aqueous sulfuric acid solution was 20 seconds.
In this Example 11, the mixed spinning aramid fabrics after
the solvent treatment step (sulfuric acid treatment step)
were injected into the subsequent post-dyeing step by a
disperse dye without drying.
[0163]
D2. Post-dyeing step by disperse dye
Dyeing was carried out by the immersion dyeing method
using a disperse dye, and the mixed spinning aramid fabrics
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after the sulfuric acid treatment was dyed by using a high
temperature and high pressure dyeing tester MINI-COLOR
(manufactured by TEXAM Giken Co., Ltd.) without drying as
mentioned above. As the dyeing solution, 10% owf of
Kayalon Polyester Navy Blue NB-E (C.I. No. unknown,
disperse dye available from NIPPON KAYAKU Co., Ltd.) was
used and an acetic acid/sodium acetate series buffer having
a pH 5 was used in combination.
[0164]
As a dyeing method, a high temperature and high
pressure dyeing was carried out by making a bath ratio of
1:100, and under the conditions at 130 C for 60 minutes.
Reduction washing was carried out to the mixed spinning
aramid fabrics after the dyeing in the same manner as in
the dyeing of ordinary polyester fibers by a disperse dye.
The reduction washing was carried out under the same
conditions of the post-dyeing step of the above-mentioned
Example 5, thereafter, washing with hot water and washing
with water were carried out and then the fabrics were dried
to obtain mixed spinning aramid fabrics of Example 11 dyed
to black which is a very dark color.
[0165]
Comparative Example 8
Similarly to the above-mentioned Example 11, a
material in which the dyeing step by the disperse dye alone
was carried out to the undying mixed spinning aramid
fabrics was made Comparative Example 8. In this Compara-
tive Example 8, the conditions of the dyeing step by the
disperse dye were made the same as those of the above-
mentioned Example 11.
[0166]
Comparative Example 9
Similarly to the above-mentioned Example 11, the
solvent treatment step (sulfuric acid treatment step) and
the dyeing step by the disperse dye alone were carried out,
which was made Comparative Example 9. That is, Comparative
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Example 9 gives a material in which the mixed spinning
aramid fabrics carried out the sulfuric acid treatment were
dyed by the disperse dye alone. In this Comparative
Example 9, the conditions of the sulfuric acid treatment
and the dyeing by the disperse dye are the same as those of
the above-mentioned Example 11.
[0167]
The dyed mixed spinning aramid fabrics of Example 11,
Comparative Example 8 and Comparative Example 9 which had
been dyed as mentioned above were evaluated in the same
manner as in the above-mentioned Example 1. However,
lightness (L* value) was not measured. The evaluation
results of the total K/S value which evaluates the color
depth and colorfastness to light are shown in Table 11.
[0168]
[Table 11]
Mixed spinning Aramid fabrics x Various
dyes x Sulfuric acid
ColorColorfast
Lightness
depth ness to
Dye (L*
(Total K/S light
value)
value) (grade)
Vat +
Example 11153 -- 3-4
Disperse
Comparative
Disperse 26 -- 1-2
example 8
Comparative
Disperse 136 -- 2-3
example 9
[0169]
As can be seen from Table 11, in Example 11, mixed
spinning aramid fabrics markedly improved in color depth
(total K/S value) and having a very dark color can be
obtained. Also, the mixed spinning aramid fabrics of
Example 11 have good colorfastness to light. Also, in the
mixed spinning aramid fabrics of this Example 11, fuzz at
the surfaces of the fabrics have been dyed by both of the
vat dye and the disperse dye to a very dark color, and
surface quality of the fabrics has been more improved.
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Further, whereas it is not shown in Table 11, in the dyed
mixed spinning aramid fabrics of Example 11, the fabrics
had maintained the practical properties of high performance
fibers without generating color unevenness or dimensional
change, or lowering in physical properties markedly. On
the other hand, in Comparative Example 8, as compared with
Example 11, color depth is inferior to that of Example, and
colorfastness to light is markedly inferior to the same
whereby no practically dyed product can be obtained. Also,
in Comparative Example 9, whereas a sufficient color depth
can be obtained, it is dyed only by the disperse dye so
that colorfastness to light is markedly inferior to the
same, and no practically dyed product can be obtained.
[0170]
Example 12
In this Example 12, aramid fabrics were dyed based on
the above-mentioned first embodiment and benzyl alcohol was
used as a polar solvent. In this Example 12, the same
para-type aramid fabrics as those used in the above-
mentioned Example 1 were used. The para-type aramid
fabrics were used after desizing and degumming by the
ordinary method.
[0171]
A. Dye providing step
In this Example 12, the following vat dye was
provided by the same operations as in the above-mentioned
Example 1. A pickup ratio at this time was 58% by weight.
As the dyeing solution, 50 g/L of the same vat dye
"Mikethren Grey M super-fine" as in the above-mentioned
Example 11 was dispersed in an unreduced state, and 10 g/L
of GERMADYE AM-X (available from RAON CHEMICAL LTD.) was
used as a migration preventive agent in combination.
[0172]
Drying was carried out in the same steps of the
above-mentioned Example 1, and the para-type aramid fabrics
after providing the dyeing solution was dried at 1100C for
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2 minutes to adhere the vat dye onto the surfaces of the
fibers of the para-type aramid fabrics. The mixed spinning
aramid fabrics after drying was injected into the subse-
quent solvent treatment step (benzyl alcohol treatment
step) as such without carrying out washing or reduction
washing.
[0173]
B. Solvent treatment step (benzyl alcohol treatment step)
In this Example 12, benzyl alcohol (99.5% product)
was used as a polar solvent without dilution. For
providing the treating solution, a mangle device for
testing was used, and the para-type aramid fabrics after
the dye providing step were subjected to the solvent treat-
ment by a continuous method. The treatment temperature at
this time was 20 C. The treatment was carried out by
immersing the para-type aramid fabrics into the treating
solution for 1 second, and immediately squeezed by the
mangle. A pickup rate at this time was 61% by weight.
Incidentally, in this Example 12, without carrying out the
heat treatment after the solvent treatment, the para-type
aramid fabrics after the solvent treatment step were washed
with hot water and washed with water to remove the
remaining benzyl alcohol, and then, reduction washing was
carried out. The reduction washing was carried out in the
same manner as in the above-mentioned Example 1.
Thereafter, washing with hot water and washing with water
were carried out and the fabrics were dried to obtain para-
type aramid fabrics of Example 12 dyed to black having a
practical color depth.
[0174]
The dyed para-type aramid fabrics of Example 12 which
had been dyed as mentioned above were evaluated in the same
manner as in the above-mentioned Example 1. The evaluation
results of the total K/S value which evaluates the color
depth, lightness (L* value) which evaluates the degree of a
dark color and colorfastness to light are shown in Table 12.
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[0175]
[Table 12]
para-type Aramid fabrics x Vat dye x Benzyl alcohol
Color
Colorfastness
depth Lightness
Solvent to light
(Total K/S (L* value)
(grade)
value)
Example 12 Benzyl 81.9 37.9 4
alcohol
[0176]
As can be seen from Table 12, in Example 12, the
para-type aramid fabrics have a practical color depth
(total K/S value) and lightness (L* value), and also have
good colorfastness to light. Further, whereas it is not
shown in Table 12, in the dyed para-type aramid fabrics of
Example 12, the fabrics had maintained the practical
properties of high performance fibers without generating
color unevenness or dimensional change, or lowering in
physical properties markedly.
[0177]
Example 13
In this Example 13, aramid fabrics were dyed based on
the above-mentioned first embodiment and benzyl alcohol was
used as a polar solvent. In this Example 13, to the dyed
para-type aramid fabrics obtained in the above-mentioned
Example 12, the same dyeing operation as in the above-
mentioned Example 12 was repeated with a plural number of
times. More specifically, the above-mentioned Example 12
was made the dyeing operation once, and the dyeing
operation in which the dye providing step and the solvent
treatment step had been combined was further repeated to
carry out a total of 2 times, a total of 3 times and a
total of 4 times of the dyeing operations. However, the
reduction washing was carried out at after the final dyeing
operation alone.
[0178]
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The dyed para-type aramid fabrics of Example 13 which
had been dyed as mentioned above were evaluated in the same
manner as in the above-mentioned Example 1. The evaluation
results of the total K/S value which evaluates the color
depth, lightness (L* value) which evaluates the degree of a
dark color and colorfastness to light are shown in Table 13.
[0179]
[Table 13]
para-type Aramid fabrics x Vat dye x Benzyl alcohol
Color
Light-
Dyeing depth
Colorfastness
ness
Solvent operation (Total (L* to light
(times) K/S (grade)
value)
value)
Example
1 81.9 37.9 4
12
Benzyl 2 129.0 28.1 4
alcohol Example
3 162.0 25.1 4-5
13
4 183.9 23.3 5
[0180]
As can be seen from Table 13, in the para-type aramid
fabrics, as compared with Example 12 in which the dyeing
operation is once, in Example 13, as a number of the dyeing
operation increases, the color depth (total K/S value) is
markedly improved, lightness (L* value) becomes small as 30
or less, whereby the para-type aramid fabrics with a very
dark color could be obtained. The para-type aramid fabrics
with a very dark color have had good colorfastness to light
as shown in Table 13. Further, whereas it is not shown in
Table 13, in the dyed para-type aramid fabrics of Example
13, the fabrics had maintained the practical properties of
high performance fibers without generating color unevenness
or dimensional change, or lowering in physical properties
markedly.
[0181]
Example 14
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In this Example 14, aramid fabrics were dyed based on
the above-mentioned second embodiment and 4 kinds of polar
solvents, triethylene glycol, formic acid, DL-lactic acid
and oxalic acid were used as a polar solvent, respectively.
In this Example 14, the same para-type aramid fabrics as in
the above-mentioned Example 1 were used. The para-type
aramid fabrics were used after desizing and degumming by
the ordinary method.
[0182]
A. Dye providing step
In this Example 14, the same vat dye "Mikethren Grey
M super-fine" was used as in the above-mentioned Example
12, and the same operations as in the above-mentioned
Example 12 were carried out. A pickup rate at this time
was 58% by weight. Drying was carried out in the same
manner as in the above-mentioned Example 12. The mixed
spinning aramid fabrics after drying was injected into the
subsequent solvent treatment step as such without carrying
out washing or reduction washing.
[0183]
B. Solvent treatment step
In this Example 14, triethylene glycol (95% product),
formic acid (98% product) and DL-lactic acid (85% product)
were each used without dilution. On the other hand, oxalic
acid (dihydrate) was dissolved in water and used as a 10%
by weight aqueous solution. For providing the treating
solution, a mangle device for testing was used, and the
para-type aramid fabrics after the dye providing step were
subjected to the solvent treatment by a continuous method.
The treatment temperature at this time was each 20 C. The
treatment was carried out by immersing the para-type aramid
fabrics in the treating solution for 1 second and then
immediately squeezed by the mangle. The pickup rates of
the respective polar solvents at this time were 75% by
weight for triethylene glycol, 71% by weight for formic
acid, 81% by weight for DL-lactic acid, and 75% by weight
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,
for an aqueous oxalic acid solution, respectively.
[0184]
C. Heat treatment step
For the heat treatment, a baking box device for
testing was used, and the dry heat treatment was carried
out to the para-type aramid fabrics after the respective
solvent treatments at 1100C for 2 minutes to adhere the vat
dye to the para-type aramid fabrics. The para-type aramid
fabrics after the heat treatment was washed with hot water
and washed with water to remove the respective polar
solvents, and dried.
[0185]
Next, reduction washing of the dyed para-type aramid
fabrics after the heat treatment step was carried out. The
reduction washing was carried out in the same manner as in
the above-mentioned Example 1. Thereafter, washing with
hot water and washing with water were carried out and the
fabrics were dried to obtain para-type aramid fabrics of
Example 14 dyed to black having a practical color depth.
[0186]
The dyed para-type aramid fabrics of Example 14 which
had been dyed as mentioned above were evaluated in the same
manner as in the above-mentioned Example 1. The evaluation
results of the total K/S value which evaluates the color
depth, lightness (L* value) which evaluates the degree of a
dark color and colorfastness to light are shown in Table 14.
[0187]
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[Table 14]
para-type Aramid fabrics x Vat dye x Various polar
solvents
Color
Light-
depth Colorfastness
ness
Dye Solvent (Total to light
(L*
K/S (grade)
value)
value)
Triethylene
95.5 33.5 4
glycol
Example Formic acid 87.8 34.3 4
Vat
14 DL-lactic
97.1 32.7 4
acid
Oxalic acid 75.5 37.3 4
[0188]
As can be seen from Table 14, in Example 14, the
para-type aramid fabrics have a practical color depth
(total K/S value) and lightness (L* value) in either of 4
kinds of the polar solvents, and also have good
colorfastness to light. Further, whereas it is not shown
in Table 14, in the dyed para-type aramid fabrics of
Example 14, the fabrics had maintained the practical
properties of high performance fibers without generating
color unevenness or dimensional change, or lowering in
physical properties markedly.
[0189]
Example 15
In this Example 15, aramid fabrics were dyed based on
the above-mentioned third embodiment (pre-dyeing by
disperse dye -> dyeing by vat dye) and 5 kinds of the polar
solvents, benzyl alcohol, triethylene glycol, formic acid,
DL-lactic acid and oxalic acid were used as a polar solvent,
respectively. In this Example 15, to the same para-type
aramid fabrics as in the above-mentioned Example 1, a pre-
dyeing step by a disperse dye was firstly carried out.
Next, to the para-type aramid fabrics after the pre-dyeing
step, the dyeing operation using the same vat dye and the
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respective polar solvents as in the above-mentioned Example
12 and Example 14 was carried out.
[0190]
D1. Pre-dyeing step by disperse dye
Undying para-type aramid fabrics were dyed by a
disperse dye after desizing and degumming by the ordinary
method. Dyeing was carried out by the immersion dyeing
method, and the para-type aramid fabrics was dyed by using
a high temperature and high pressure dyeing tester MINI-
COLOR (manufactured by TEXAM Giken Co., Ltd.). As the
dyeing solution, 2.5% owf of Kayalon Polyester Black ECX-
300 (disperse dye available from NIPPON KAYAKU Co., Ltd.,
C.I. No. unknown) and 2.5% owf of Kayalon Polyester Black
TN-200 (C.I. No. unknown, disperse dye available from
NIPPON KAYAKU Co., Ltd.) were used in combination, and an
acetic acid/sodium acetate series buffer with pH 5 was used.
[0191]
As a dyeing method, a high temperature and high
pressure dyeing was carried out by making a bath ratio of
1:20, and under the conditions at 135 C for 60 minutes.
Reduction washing was carried out to the para-type aramid
fabrics after dyeing in the same manner as in the dyeing of
ordinary polyester fibers by a disperse dye. The reduction
washing was carried out under the conditions of using 5 g/L
of sodium dithionite as a reducing agent in combination
with 5 g/L of sodium hydroxide at 80 C for 1 minute, and in
this Example 15, reduction washing was repeated twice.
Thereafter, washing with hot water and washing with water
were carried out and the fabrics were dried to obtain para-
type aramid fabrics which had been carried out the pre-
dyeing by the disperse dye.
[0192]
Next, the dyeing operations each of which uses benzyl
alcohol, triethylene glycol, formic acid, DL-lactic acid or
oxalic acid as a polar solvent, and the reduction washing
were carried out to the para-type aramid fabrics carried
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out the pre-dyeing in the same manner as in the above-
mentioned Example 12 or the above-mentioned Example 14 to
obtain para-type aramid fabrics of Example 15 dyed to black
which is a very dark color.
[0193]
The dyed para-type aramid fabrics of Example 15 which
had been dyed as mentioned above were evaluated in the same
manner as in the above-mentioned Example 1. The evaluation
results of the total K/S value which evaluates the color
depth, lightness (L* value) which evaluates the degree of a
dark color and colorfastness to light are shown in Table 15.
[0194]
[Table 15]
para-type Aramid fabrics x Disperse dye+Vat
dye x Various polar solvents
Color
Light-
depth Colorfastness
Dye Solvent (Total ness to light
(L*
K/S (grade)
value)
value)
Benzyl
119.4 28.8 4
alcohol
Triethylene
135.6 26.8 4
Example Disperse glycol
15 + Vat Formic acid 120.4 28.3 4
DL-lactic
130.3 27.4 4
acid
Oxalic acid 142.6 26.4 4
[0195]
As can be seen from Table 15, as compared with the
above-mentioned Example 12 (see Table 12) or the above-
mentioned Example 14 (see Table 14) which had been dyed
only by the vat dye, in Example 15 in which the pre-dyeing
by the disperse dye has been carried out, dyeing densities
(total K/S value) are markedly improved, and lightnesses
(L* value) become small as 30 or less, and the para-type
aramid fabrics with a very dark color can be obtained in
the respective samples. The para-type aramid fabrics with
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a very dark color have extremely good colorfastness to
light as shown in Table 15. Also, in the para-type aramid
fabrics of this Example 15, fuzz at the surfaces of the
fabrics have been dyed to a very dark color by both of the
vat dye and the disperse dye, and the surface qualities of
the fabrics has been improved. Further, whereas it is not
shown in Table 15, in the dyed para-type aramid fabrics of
Example 15, the fabrics had maintained the practical
properties of high performance fibers without generating
color unevenness or dimensional change, or lowering in
physical properties markedly.
[0196]
Example 16
In this Example 16, aramid fabrics were dyed based on
the above-mentioned third embodiment (pre-dyeing by
cationic dye -> dyeing by vat dye) and DL-lactic acid was
used as a polar solvent. In this Example 16, to the same
para-type aramid fabrics as in the above-mentioned Example
1, a pre-dyeing step by a cationic dye was firstly carried
out. Next, to the para-type aramid fabrics after the pre-
dyeing step, a dyeing operation by the same vat dye as in
the above-mentioned Example 14 and by DL-lactic acid was
carried out.
[0197]
Dl. Pre-dyeing step by cationic dye
Undyed para-type aramid fabrics were dyed by a
cationic dye after desizing and degumming by the ordinary
method. Dyeing was carried out by the immersion dyeing
method, and the para-type aramid fabrics was dyed by using
a high temperature and high pressure dyeing tester MINI-
COLOR (manufactured by TEXAM Giken Co., Ltd.). As the
dyeing solution, 5.0% owf of Kayacryl Navy RP-ED (C.I. No.
unknown, cationic dye available from NIPPON KAYAKU Co.,
Ltd.) was used and 25 g/L of sodium nitrate and a comer-
cially available dyeing carrier were also used in
combination, and an acetic acid/sodium acetate series
CA 02830147 2013-09-13
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,
buffer with pH 5 was used.
[0198]
As a dyeing method, a high temperature and high
pressure dyeing was carried out by making a bath ratio of
1:20, and under the conditions at 135 C for 60 minutes.
The para-type aramid fabrics after dyeing were carried out
washing with hot water and washing with water, and dried to
obtain para-type aramid fabrics which have been carried out
a pre-drying by a cationic dye.
[0199]
Next, to the para-type aramid fabrics which have been
carried out the pre-drying, the dye providing step was
carried out by using 50 g/L of the same vat dye "Mikethren
Blue BC super-fine" as in the above-mentioned Example 1
according to the same operations as in the above-mentioned
Example 12. A pickup rate at this time was 58% by weight.
Further, to the para-type aramid fabrics after the dye
providing step, the solvent treatment step using DL-lactic
acid as a polar solvent, the heat treatment step and the
reduction washing were carried out in the same manner as in
the above-mentioned Example 14 to obtain para-type aramid
fabrics of Example 16 dyed to navy blue which is a very
dark color.
[0200]
Comparative Example 10
Similarly to the above-mentioned Example 16, dyeing
by a cationic dye alone was carried out to the para-type
aramid fabrics, which was made Comparative Example 10.
More specifically, none of the dyeing operation of the dye
providing step, the solvent treatment step and the heat
treatment step according to the present invention was
carried out, but the dyeing step by a cationic dye was
carried out in the same manner as in the above-mentioned
Example 16, thereafter, reduction washing, washing with hot
water and washing with water were carried out to the
fabrics in the same manner as in Example 16, and the
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fabrics were dried to obtain para-type aramid fabrics of
Comparative Example 10 dyed to navy blue.
[0201]
The dyed para-type aramid fabrics of Example 16 and
Comparative Example 10 which had been dyed as mentioned
above were evaluated in the same manner as in the above-
mentioned Example 1. The evaluation results of the total
K/S value which evaluates the color depth, lightness (L*
value) which evaluates the degree of a dark color and
colorfastness to light are shown in Table 16.
[0202]
[Table 16]
para-type Aramid fabrics x Disperse dye+Vat
dye x Various polar solvents
Color
Light-
depth Colorfastness
ness
Solvent Dye (Total ( L * to light
K/S (grade)
value)
value)
Example 16 Cation
DL- 137.8 26.3 3
+ Vat
lactic
Comparative
acid Cation 68.0 36.0 1
Example 10
[0203]
As can be seen from Table 16, in Example 16 dyed by
the cationic dye and the vat dye, as compared with
Comparative Example 10 dyed by the cationic dye alone,
para-type aramid fabrics having a large color depth (total
K/S value), and lightness (L* value) of as small as 30 or
less, with a very dark color can be obtained. On the other
hand, whereas colorfastness to light of Comparative Example
which has been dyed only by the cationic dye is
remarkably weak, in Example 16 which has been dyed not only
by the cationic dye but also by the vat dye, remarkable
improvement in colorfastness to light can be recognized.
Also, in the para-type aramid fabrics of this Example 16,
fuzz at the surfaces of the fabrics have been dyed to a
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very dark color by both of the cationic dye and the vat dye,
and surface quality of the fabrics has been more improved.
Further, whereas it is not shown in Table 16, in the dyed
para-type aramid fabrics of Example 16, the fabrics had
maintained the practical properties of high performance
fibers without generating color unevenness or dimensional
change, or lowering in physical properties markedly.
[0204]
As explained in the dyeing operations of the above-
mentioned Example 1 to Example 16, according to the present
invention, it can be applied to either of the para-type
aramid fibers, the para-type copolymerized aramid fibers
and the meta-type aramid fibers, and these aramid fibers
can be dyed to a practical color depth. Also, according to
the present invention, color unevenness or dimensional
change, or lowering in physical properties is not markedly
generated in the aramid fibers after the dyeing. Further,
a vat dye or a sulfur dye having good colorfastness, in
particular, good colorfastness to light is used so that
colorfastness, in particular, colorfastness to light of the
dyed aramid fibers becomes good.
[0205]
Also, by changing a used concentration and hue of the
vat dye or the sulfur dye to be used, dyed products with
various huess from a pale color to a dark color can be
obtained. In particular, according to the present
invention, para-type aramid fibers or para-type copoly-
merized aramid fibers can be dyed to a very dark color (for
example, L* value is 30 or less) such as black and navy
blue which has been considered to be difficult as of today.
[0206]
Further, as a pre- or post-step of the method for
dyeing aramid fibers according to the present invention, by
carrying out the pre-dyeing step or the post-dyeing step
using a dye other than the vat dye and the sulfur dye, fuzz
at the surface of the aramid fibers themselves are suffi-
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ciently dyed, dyeing quality becomes good, and further the
color depth is improved. On the other hand, when the
aramid fibers constitute mixed fibers with the other
chemical fibers or natural fibers, by carrying out these
dyeing steps, hue of the aramid fibers and that of the
other fibers can be unified, whereby the dyeing quality and
the color depth of the dyed product are further improved.
[0207]
Therefore, according to the present invention, a
method for dyeing aramid fibers and dyed aramid fibers in
which colorfastness, in particular, colorfastness to light
of the dyed product is good, hue thereof is abundant and
the product has a practical color depth can be provided.
This is effective for new applications of the aramid fibers.
[0208]
Incidentally, for practicing the present invention,
it is not limited by the above-mentioned respective
Examples, the following various modified examples may be
mentioned.
(1) In the above-mentioned respective Examples, the solvent
treatment step is carried out after the dye providing step,
but the embodiment is not limited thereto, and the dye
providing step may be carried out after the solvent
treatment step.
(2) In the above-mentioned respective Examples, after
providing the dyeing solution containing the vat dye or the
sulfur dye to the aramid fabrics, the said aramid fabrics
are dried, but the embodiment is not limited thereto, and
after providing the dyeing solution, the aramid fabrics may
be injected into the solvent treatment step without drying.
(3) In the above-mentioned respective Examples, whereas
navy blue or black are used in many cases except for a part
of vivid hue, these Examples are merely to show that
fabrics can be dyed to a dark color or very dark color.
Accordingly, by changing a used concentration and hue of
the vat dye or the sulfur dye to be used, a dyed product
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from a pale color to a dark color with various hues
including vivid hue can be obtained.
(4) In the above-mentioned respective Examples, the aramid
fibers to which the vat dye or the sulfur dye has been
added in the dye providing step was injected into the
subsequent solvent treatment step without washing. However,
the vat dye or the sulfur dye is adhered to the aramid
fibers with a certain degree of affinity after the dye
providing step. Accordingly, the aramid fibers after the
dye providing step may be injected into the solvent
treatment step after washing.
(5) In the above-mentioned respective Examples, reduction
washing is carried out after the dyeing operation in some
cases, but the reduction washing may be carried out only in
the case where it is required, and a prescription of the
reduction washing is not limited only to an alkaline series,
and a reduction washing may be carried out with an acidic
series reduction prescription.
(6) In the above-mentioned Example 14 and Example 15, DL-
lactic acid in which optical isomers have been mixed was
used as a polar solvent, but the embodiment is not limited
thereto, and D-lactic acid or L-lactic acid may be used.
(7) In the above-mentioned Example 5, Example 11 and
Example 15, neither a dyeing carrier nor a deep coloring
agent is used for dyeing by a disperse dye. In the present
invention, the pre-dyeing or the post-dyeing is merely
auxiliary dyeing, and a dyeing carrier, etc., may not be
used. However, by using various kinds of dyeing carriers,
etc., used in the ordinary aramid dyeing in combination,
the fabrics may be dyed to a darker color.
(8) In the above-mentioned respective Examples, dyeing was
carried out to the aramid fabrics, but the embodiment is
not limited thereto, and it may be knitted fabrics,
nonwoven fabrics, etc., or may be yarn, cotton, etc.
