U.S. patent application number 14/007819 was filed with the patent office on 2014-01-23 for method for dyeing aramid fibers and dyed aramid fibers.
This patent application is currently assigned to Tokai Senko K.K.. The applicant listed for this patent is Kazuki Imai, Takahiro Ito, Norihiro Oiwa, Shohei Sayama, Akira Yasui. Invention is credited to Kazuki Imai, Takahiro Ito, Norihiro Oiwa, Shohei Sayama, Akira Yasui.
Application Number | 20140020190 14/007819 |
Document ID | / |
Family ID | 46931364 |
Filed Date | 2014-01-23 |
United States Patent
Application |
20140020190 |
Kind Code |
A1 |
Oiwa; Norihiro ; et
al. |
January 23, 2014 |
Method for Dyeing Aramid Fibers and Dyed Aramid Fibers
Abstract
Methods for dyeing aramid fibers, and the dyed arimid fibers
produced by these methods, which comprises 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 one or
more dyeing operations comprising the combination of the respective
steps dyeing operations. The dyeing methods 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. Colorfastness of the dyed product, in
particular, colorfastness to light, is improved.
Inventors: |
Oiwa; Norihiro; (Kiyosu-shi,
JP) ; Imai; Kazuki; (Kiyosu-shi, JP) ; Sayama;
Shohei; (Kiyosu-shi, JP) ; Ito; Takahiro;
(Kiyosu-shi, JP) ; Yasui; Akira; (Kiyosu-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Oiwa; Norihiro
Imai; Kazuki
Sayama; Shohei
Ito; Takahiro
Yasui; Akira |
Kiyosu-shi
Kiyosu-shi
Kiyosu-shi
Kiyosu-shi
Kiyosu-shi |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
Tokai Senko K.K.
Kiyosu-shi
JP
|
Family ID: |
46931364 |
Appl. No.: |
14/007819 |
Filed: |
March 29, 2012 |
PCT Filed: |
March 29, 2012 |
PCT NO: |
PCT/JP2012/058390 |
371 Date: |
September 26, 2013 |
Current U.S.
Class: |
8/650 ; 8/115.56;
8/115.59; 8/115.65 |
Current CPC
Class: |
D06P 1/30 20130101; D06P
5/02 20130101; D06P 1/22 20130101; D06P 3/243 20130101; D06P 5/001
20130101; D06P 5/22 20130101 |
Class at
Publication: |
8/650 ; 8/115.59;
8/115.65; 8/115.56 |
International
Class: |
D06P 5/22 20060101
D06P005/22 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2011 |
JP |
2011-074295 |
May 10, 2011 |
JP |
2011-104846 |
Claims
1. A method for dyeing aramid fibers which comprises 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, dyeing operation 1: dye providing step followed
by solvent treatment step, dyeing operation 2: solvent treatment
step followed by dye providing step, dyeing operation 3: dye
providing step followed by solvent treatment step followed by heat
treatment step, dyeing operation 4: solvent treatment step followed
by heat treatment step followed by dye providing step, once or
more.
2. The method for dyeing aramid fibers according to claim 1,
wherein the polar solvent has a value of a solubility parameter
(.delta.) within the range of 18 to 32 (MPa).sup.1/2.
3. The method for dyeing aramid fibers according to claim 1,
wherein the polar solvent is at least one selected from the group
consisting of N-methylpyrrolidone, N,N-dimethylformamide,
N,N-dimethylacetamide, dimethylsulfoxide, benzyl alcohol,
diethylene glycol, triethylene glycol, sulfuric acid, formic acid,
lactic acid and oxalic acid.
4. A method for dyeing aramid fibers which comprises the method for
dyeing aramid fibers according to claim 1, 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.
5. Dyed aramid fibers which are dyed by the method for dyeing
aramid fibers according to claim 1.
6. The dyed aramid fibers according to claim 5, wherein lightness
(L* value) in an L*a*b* colorimetric system thereof is 38 or
less.
7. The dyed aramid fibers according to claim 5, wherein lightness
(L* value) in an L*a*b* colorimetric system thereof is 30 or
less.
8. Dyed aramid fibers which are dyed by the method for dyeing
aramid fibers according to claim 4.
9. The dyed aramid fibers according to claim 8, wherein lightness
(L* value) in an L*a*b* colorimetric system thereof is 30 or less.
Description
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 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 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
temperature is used, and dyeing is carried out at extremely high
temperature conditions of 300 to 400.degree. C. has been
proposed.
PRIOR ART DOCUMENT
Patent Document
[0007] Patent Document 1: JP Sho 52-37882A [0008] Patent Document
2: JP 2010-59556A
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0009] By the way, the dyeing method of the above-mentioned Patent
Document 1 gives a dyed product with various hues. 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.
[0010] 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.
[0011] 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, colorfastness of the dyed product, in
particular, colorfastness to light is good.
Means to Solve the Problems
[0012] 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.
[0013] 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,
dyeing operation 1: dye providing step.fwdarw.solvent treatment
step, dyeing operation 2: solvent treatment step.fwdarw.dye
providing step, dyeing operation 3: dye providing
step.fwdarw.solvent treatment step.fwdarw.heat treatment step,
dyeing operation 4: solvent treatment step.fwdarw.heat treatment
step.fwdarw.dye providing step, once or more.
[0014] 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 (.delta.) within a range of 18 to 32 (MPa).sup.1/2.
[0015] 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-methylpyrrolidone, N,N-dimethylformamide,
N,N-dimethylacetamide, dimethylsulfoxide, benzyl alcohol,
diethylene glycol, triethylene glycol, sulfuric acid, formic acid,
lactic acid and oxalic acid.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] Also, the present invention is, according to the 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.
[0020] 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.
[0021] 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
[0022] 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.
[0023] 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 be difficult.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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
[0028] 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.
[0029] 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.
[0030] In the present invention, the aramid fibers are dyed 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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 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.
[0035] 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
[0036] 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.
[0037] In this first embodiment, these series of steps are
generically called as "dyeing operation 1". Incidentally, this
dyeing operation 1 (dye providing step.fwdarw.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.
A. Dye Providing Step
[0038] The vat dye to be used in the dye providing step may be
mentioned a dye generally used for dyeing of cotton, etc. 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 .mu.m or less, more
preferably 1 .mu.m 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.
[0039] 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.
[0040] 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.
[0041] 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.degree. C. to 120.degree. C. In
addition, after drying the aramid fibers, a heat 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.degree. C. to
200.degree. C., or a higher temperature than the above, which also
acts as drying procedure.
[0042] If the drying temperature is lower than 80.degree. C., a
longer time is required for drying the aramid fibers. On the other
hand, if the treatment temperature is higher than 200.degree. C.,
in particular, it is higher than 280.degree. 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.
[0043] 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.degree. C.
[0044] 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 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.
[0045] 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.
B. Solvent Treatment Step
[0046] 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 difficulty
causes shrinkage or lowering in 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.
[0047] 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-.beta.-ethylphenethyl
alcohol, 2-ethoxybenzyl alcohol, 3-chlorobenzyl alcohol,
2,5-dimethylbenzyl alcohol, 2-nitrobenzyl alcohol,
p-isopropylbenzyl alcohol, 2-methylphenethyl alcohol,
3-methylphenethyl alcohol, 4-methylphenethyl 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 difficulty causes shrinkage or lowering in physical
properties of the aramid fibers, and particularly effective 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.
[0048] Also, as a quantitative index which shows polarity of the
polar solvent used in the present invention, a solubility parameter
(.delta.) 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 .delta.=18 to 32 (MPa).sup.1/2. Moreover, it is
more preferred to use a polar solvent having a value of the
solubility parameter within the range of .delta.=19 to 28
(MPa).sup.1/2. Here, for example, the value of the solubility
parameter of the para-type aramid fibers is to be made .delta.=23
(MPa).sup.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.
[0049] 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, as far
as the oxalic acid is concerned, it is preferred to use as an
aqueous solution of about 10% by weight.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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 solvent
treatment solution in some cases.
[0054] 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.degree. C. to 70.degree. C. In
addition, it is preferably a temperature of 10.degree. C. to
60.degree. C. When sulfuric acid is used, the temperature of the
aqueous sulfuric acid solution may be a temperature of 0.degree. C.
or higher and 50.degree. C. or lower, and more preferably at a
temperature of 0.degree. C. or higher and 30.degree. C. or
lower.
[0055] 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.
[0056] 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 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.
[0057] 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.
[0058] 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. Subsequently, 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.
[0059] 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.
[0060] 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.fwdarw.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.
[0061] Also, by repeating the above-mentioned dyeing operation 1
(dye providing step.fwdarw.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 the
above, colorfastness of the dyed product dyed to a dense color can
be maintained with a good state.
(2) Second Embodiment
[0062] 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".
Incidentally, the dyeing operation 3 (dye providing
step.fwdarw.solvent treatment step.fwdarw.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.
A. Dye Providing Step
[0063] 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.
B. Solvent Treatment Step
[0064] 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 embodiment.
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.
C. Heat Treatment Step
[0065] After the above-mentioned solvent treatment step, the aramid
fibers have already been dyed by the vat dye or the 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.
[0066] 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.degree. C. or higher and 200.degree. 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.degree. 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.
[0067] 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 particular 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.
[0068] Here, when the aramid fibers are a fabric state, the 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 treatment 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] In this second embodiment, as mentioned above, the 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.fwdarw.solvent treatment
step.fwdarw.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.
[0073] Also, by repeating the above-mentioned dyeing operation 3
(dye providing step.fwdarw.solvent treatment step.fwdarw.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
[0074] 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 dyeing
operation 3 a plural number of times, aramid fibers with a denser
color can be obtained.
D1. Pre-Dyeing Step
[0075] 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.
[0076] 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 direct dye, etc., may be used.
[0077] 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.degree. C. to
150.degree. C. Also, the temperature is preferably 100.degree. C.
to 140.degree. C., and more preferably the temperature is
120.degree. C. to 135.degree. C. If the temperature exceeds
100.degree. C. in the dyeing, high temperature and high pressure
dyeing machine is used.
[0078] When the aramid fibers themselves are to be dyed, if the
dyeing temperature is lower than 80.degree. C., sufficient color
depth cannot be obtained, on the other hand, if the dyeing
temperature is higher than 150.degree. 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.
[0079] 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.degree. 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.
[0080] 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.
A. Dye Providing Step
[0081] 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.
B. Solvent Treatment Step
[0082] 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.
C. Heat Treatment Step
[0083] 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.
[0084] 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.
[0085] 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 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
[0086] 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.
A. Dye Providing Step
[0087] 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.
B. Solvent Treatment Step
[0088] 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.
C. Heat Treatment Step
[0089] 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.
D2. Post-Dyeing Step
[0090] 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.
[0091] 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.
[0092] 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 fibers can be unified, whereby the
dyeing quality and the color depth of the dyed product are further
improved.
EXAMPLES
[0093] 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.
Example 1
[0094] 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/m.sup.2 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/m.sup.2 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/m.sup.2 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.
A. Dye Providing Step
[0095] Dye providing procedure was carried out by a continuous
method using a mangle device for testing, and 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.
[0096] 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.).
[0097] 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.degree. 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.
B. Solvent Treatment Step (N-methyl-2-pyrrolidone Treatment
Step)
[0098] 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.degree. 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
weight for the para-type copolymerized aramid fabrics, and 62% by
weight for the meta-type aramid fabrics.
C. Heat Treatment Step
[0099] 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.degree. 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-methyl-2-pyrrolidone by washing with water
and washing with hot water.
[0100] 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.degree.
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.
Comparative Example 1
[0101] Similarly to the above-mentioned Example 1, 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 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 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.
[0102] 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.
Color Depth (Total K/S Value):
[0103] 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 coefficient.
K/S=(1-R).sup.2/2R
[0104] Incidentally, the value of the reflectance R at the
respective wavelengths was measured by using a spectrophotometer
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.
Lightness (L* Value)
[0105] A degree of the dense color of each of the dyed aramid
fabrics was evaluated by lightness (L* value) in the
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.
Colorfastness:
[0106] 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 difficulty 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.
TABLE-US-00001 TABLE 1 <<Each Aramid fabrics>> .times.
<<Vat dye>> .times.
<<N-methyl-2-pyrrolidone>> Example 1 Comparative
Example 1 Color Color- Color Color- depth Light- fast- depth Light-
fast- (Total ness ness to (Total ness ness to Aramid K/S (L* light
K/S (L* light fabrics value) value) (grade) value) value) (grade)
para-type 72.3 36.4 4 52.0 45.0 3-4 para-type 85.0 31.1 4-5 80.7
36.8 4 copoly- merized meta-type 50.3 35.2 3-4 6.6 76.9 2
[0107] 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.
Example 2
[0108] In this Example 2, 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 2, twilled fabrics
(hereinafter referred to as "mixed spinning aramid fabrics") having
an areal weight of 160 g/m.sup.2 and using No. 40 count two folded
yarns in which 95% by weight 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.
A. Dye Providing Step
[0109] 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.).
[0110] 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.degree. 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-methyl-2-pyrrolidone treatment
step) as such without carrying out washing or reduction
washing.
B. Solvent Treatment Step (N-methyl-2-pyrrolidone Treatment
Step)
[0111] 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
continuous method. The treatment temperature at this time was
50.degree. C.
[0112] 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.
C. Heat Treatment Step
[0113] 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.degree. 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.
Comparative Example 2
[0114] 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.
[0115] The dyed mixed spinning aramid fabrics of Example 2 and
Comparative Example 2 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 2.
TABLE-US-00002 TABLE 2 <<Mixed spinning aramid
fabrics>> .times. <<Sulfur dye>> .times.
<<N-methyl-2-pyrrolidone>> Example 2 Comparative
Example 2 Color Color- Color Color- depth Light- fast- depth Light-
fast- (Total ness ness to (Total ness ness to Aramid K/S (L* light
K/S (L* light fabrics value) value) (grade) value) value) (grade)
Mixed 108.2 27.1 3-4 39.8 44.0 3 spinning
[0116] 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.
Example 3
[0117] 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, to each of the dyed
aramid fabrics obtained in the above-mentioned Example 1 were
repeated the same dyeing operations 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
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 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.
[0118] 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.
TABLE-US-00003 TABLE 3 <<Each Aramid
fabrics>>x<<Vat dye>>x<<N-methyl-2-
pyrrolidone>> Color depth Color- Dyeing (Total Lightness
fastness Aramid operation K/S (L* to light fabrics (times) value)
value) (grade) para-type Example 1 1 72.3 36.4 4 Example 3 3 107.3
31.1 4 5 119.9 29.3 4-5 7 123.9 29.0 5 para-type Example 1 1 85.0
31.1 4-5 copolymerized Example 3 3 134.9 26.7 4-5 5 158.9 24.5 5 7
173.5 23.6 5 meta-type Example 1 1 50.3 35.2 3-4 Example 3 3 104.8
29.5 4 5 134.5 25.4 4-5 7 167.5 23.8 5
[0119] 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.
Example 4
[0120] In this Example 4, 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 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.
[0121] 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.
TABLE-US-00004 TABLE 4 <<Each Aramid
fabrics>>x<<Vat dye>>x<<N-methyl-2-
pyrrolidone>> Color depth Dyeing (Total Lightness
Colorfastness Aramid operation K/S (L* to light fabrics (times)
value) value) (grade) Example 4 para- 1 44.2 54.8 4 type 2 57.9
50.0 4-5 3 62.2 47.6 5 para- 1 53.4 48.7 4-5 type 2 80.1 43.8 4-5
copol- 3 92.1 41.9 5 ymerized 1 39.6 49.9 3-4 meta- 2 66.3 44.9 4
type 3 78.2 42.5 5
[0122] 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.
Example 5
[0123] In this Example 5, aramid fabrics were dyed according to the
above-mentioned fourth embodiment (dyeing by a vat
dye.fwdarw.post-dyeing by a disperse dye) and
N-methyl-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.
D2. Post-Dyeing Step by Disperse Dye
[0124] 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.
[0125] 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.degree. 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.degree. 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.
Comparative Example 3
[0126] Similarly to the above-mentioned Example 5, a 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.
Comparative Example 4
[0127] 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.
[0128] 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.
TABLE-US-00005 TABLE 5 <<Each Aramid
fabrics>>x<<Vat dye + Disperse dye>>x<<N-
methyl-2-pyrrolidone>> Color depth Light- (Total ness
Colorfastness Aramid K/S (L* to light fabrics Dye value) value)
(grade) para- Example 5 Vat + 110.2 29.0 4-5 type Disperse Example
1 Vat 72.3 36.4 4 Comparative Disperse 67.8 40.8 3-4 example 3
Comparative Disperse 71.7 39.4 3-4 example 4 para- Example 5 Vat +
124.6 27.7 5 type Disperse copol- Example 1 Vat 85.0 31.1 4-5
ymerized Comparative Disperse 31.3 55.1 3-4 example 3 Comparative
Disperse 50.6 43.4 4 example 4 meta- Example 5 Vat + 103.2 29.8 4
type Disperse Example 1 Vat 50.3 35.2 3-4 Comparative Disperse 17.5
56.9 2 example 3 Comparative Disperse 49.4 41.2 3 example 4
[0129] 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 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.
[0130] 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.
Example 6
[0131] 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.
A. Dye Providing Step
[0132] In this Example 6, the vat dye "Mikethren Blue BC
super-fine" which is the same as used in the above-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.
[0133] 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.degree. 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.
B. Solvent Treatment Step (Sulfuric Acid Treatment Step)
[0134] 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.degree. 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.
[0135] 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 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.
Comparative Example 5
[0136] 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.
[0137] 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.
TABLE-US-00006 TABLE 6 <<Mixed spinning Aramid
fabrics>> .times. <<Vat dye>> .times.
<<Sulfuric acid>> Example 6 Comparative Example 5 Color
Color- Color Color- depth Light- fast- depth Light- fast- (Total
ness ness to (Total ness ness to Vat K/S (L* light K/S (L* light
dye value) value) (grade) value) 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
[0138] 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.
Example 7
[0139] In this Example 7, aramid fabrics were dyed based on the
above-mentioned first embodiment and sulfuric acid was 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.
[0140] 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.
TABLE-US-00007 TABLE 7 <<Mixed spinning Aramid
fabrics>>x<<Vat dye>>x<<Sulfuric
acid>> Color depth Colorfastness Dyeing (Total Lightness to
operation K/S (L* light Vat dye (times) value) value) (grade) Blue
BC Example 6 1 86.6 31.0 4 Example 7 3 142.6 24.1 4-5 5 169.3 21.8
5 7 199.6 20.3 5
[0141] 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.
[0142] 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.
Example 8
[0143] 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.
A. Dye Providing Step
[0144] 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 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.).
[0145] 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.degree. 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.
B. Solvent Treatment Step (Sulfuric Acid Treatment Step)
[0146] 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.degree. 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.
Comparative Example 6
[0147] 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 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.
[0148] 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.
TABLE-US-00008 TABLE 8 <<Mixed spinning Aramid
fabrics>> .times. <<Sulfur dye>> .times.
<<Sulfuric acid>> Example 8 Comparative Example 6 Color
Color- Color Color- depth Light- fast- depth Light- fast- (Total
ness ness to (Total ness ness to Sulfur K/S (L* light K/S (L* light
dye value) value) (grade) value) 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 Green 16.6 -- 3 5.4 -- 2-3 S-BG
[0149] 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 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.
Example 9
[0150] 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/m.sup.2 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.
[0151] 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.
Comparative Example 7
[0152] Similarly to the above-mentioned Example 9, the dye
providing step alone was carried out to the para-type 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. Thereafter,
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.
[0153] 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.
TABLE-US-00009 TABLE 9 <<para-type single yarn Aramid
fabrics>> .times. <<Vat dye>> .times.
<<Sulfuric acid>> Example 9 Comparative Example 7 Color
Color- Color Color- depth Light- fast- depth Light- fast- (Total
ness ness to (Total ness ness to Vat K/S (L* light K/S (L* light
dye value) value) (grade) value) value) (grade) Blue BC 50.0 -- 3-4
30.4 -- 3 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 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.
Example 10
[0155] 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.
TABLE-US-00010 TABLE 10 <<para-type single yarn Aramid
fabrics>>x<<Vat dye>>x<<Sulfuric
acid>> Color depth Colorfastness Dyeing (Total Lightness to
operation K/S (L* light Vat dye (times) value) value) (grade) Blue
BC Example 9 1 50.0 -- 3-4 Example 3 70.6 -- 4 10 5 75.9 -- 5 7
88.1 -- 5
[0157] 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.
Example 11
[0158] 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.
A. Dye Providing Step
[0159] 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.
[0160] 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.degree. 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.
B. Solvent Treatment Step (Sulfuric Acid Treatment Step)
[0161] 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.degree. 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.
D2. Post-Dyeing Step by Disperse Dye
[0162] Dyeing was carried out by the immersion dyeing method using
a disperse dye, and the mixed spinning aramid fabrics 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.
[0163] 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.degree. 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.
Comparative Example 8
[0164] 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 Comparative Example 8, the conditions of the
dyeing step by the disperse dye were made the same as those of the
above-mentioned Example 11.
Comparative Example 9
[0165] 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 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.
[0166] 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.
TABLE-US-00011 TABLE 11 <<Mixed spinning Aramid
fabrics>>x<<Various dyes>>x<<Sulfuric
acid>> Color depth Lightness Colorfastness to (Total K/S (L*
light Dye value) value) (grade) Example 11 Vat + 153 -- 3-4
Disperse Comparative Disperse 26 -- 1-2 example 8 Comparative
Disperse 136 -- 2-3 example 9
[0167] 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. 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.
Example 12
[0168] 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.
A. Dye Providing Step
[0169] 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.
[0170] 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 110.degree. C. for 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 subsequent solvent treatment
step (benzyl alcohol treatment step) as such without carrying out
washing or reduction washing.
B. Solvent Treatment Step (Benzyl Alcohol Treatment Step)
[0171] 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 treatment by a continuous method. The treatment temperature
at this time was 20.degree. 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.
[0172] 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.
TABLE-US-00012 TABLE 12 <<para-type Aramid
fabrics>>x<<Vat dye>>x<<Benzyl
alcohol>> Color depth Colorfastness (Total K/S Lightness to
light Solvent value) (L* value) (grade) Example 12 Benzyl 81.9 37.9
4 alcohol
[0173] 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.
Example 13
[0174] 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.
[0175] 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.
TABLE-US-00013 TABLE 13 <<para-type Aramid
fabrics>>x<<Vat dye>>x<<Benzyl
alcohol>> Color depth Dyeing (Total Lightness Colorfastness
operation K/S (L* to light Solvent (times) value) value) (grade)
Benzyl Example 1 81.9 37.9 4 alcohol 12 Example 2 129.0 28.1 4 13 3
162.0 25.1 4-5 4 183.9 23.3 5
[0176] 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.
Example 14
[0177] 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.
A. Dye Providing Step
[0178] 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.
B. Solvent Treatment Step
[0179] 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.degree.
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 for an aqueous oxalic acid solution,
respectively.
C. Heat Treatment Step
[0180] 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
110.degree. C. 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.
[0181] 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.
[0182] 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.
TABLE-US-00014 TABLE 14 <<para-type Aramid
fabrics>>x<<Vat dye>>x<<Various polar
solvents>> Color depth (Total Lightness Colorfastness K/S (L*
to light Dye Solvent value) value) (grade) Example Vat Triethylene
95.5 33.5 4 14 glycol Formic acid 87.8 34.3 4 DL-lactic 97.1 32.7 4
acid Oxalic acid 75.5 37.3 4
[0183] 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.
Example 15
[0184] In this Example 15, aramid fabrics were dyed based on the
above-mentioned third embodiment (pre-dyeing by disperse
dye.fwdarw.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 respective polar solvents as in the above-mentioned Example
12 and Example 14 was carried out.
D1. Pre-Dyeing Step by Disperse Dye
[0185] 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.
[0186] 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.degree. 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.degree. 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.
[0187] 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 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.
[0188] 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.
TABLE-US-00015 TABLE 15 <<para-type Aramid
fabrics>>x<<Disperse dye + Vat
dye>>x<<Various polar solvents>> Color depth
(Total Lightness Colorfastness K/S (L* to light Dye Solvent value)
value) (grade) Exam- Disperse + Benzyl 119.4 28.8 4 ple 15 Vat
alcohol Triethylene 135.6 26.8 4 glycol Formic acid 120.4 28.3 4
DL-lactic 130.3 27.4 4 acid Oxalic acid 142.6 26.4 4
[0189] 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 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.
Example 16
[0190] In this Example 16, aramid fabrics were dyed based on the
above-mentioned third embodiment (pre-dyeing by cationic
dye.fwdarw.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.
D1. Pre-Dyeing Step by Cationic Dye
[0191] 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 commercially
available dyeing carrier were also used in combination, and an
acetic acid/sodium acetate series buffer with pH 5 was used.
[0192] 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.degree. 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.
[0193] 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.
Comparative Example 10
[0194] 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 fabrics were dried to obtain
para-type aramid fabrics of Comparative Example 10 dyed to navy
blue.
[0195] 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.
TABLE-US-00016 TABLE 16 <<para-type Aramid
fabrics>>x<<Disperse dye + Vat
dye>>x<<Various polar solvents>> Color depth
(Total Lightness Colorfastness K/S (L* to light Solvent Dye value)
value) (grade) DL- Example 16 Cation + 137.8 26.3 3 lactic Vat acid
Comparative Cation 68.0 36.0 1 Example 10
[0196] 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 10 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 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.
[0197] 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.
[0198] 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 copolymerized 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.
[0199] 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 sufficiently 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.
[0200] 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.
[0201] 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 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.
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