Title of Invention: Spun-dyed meta-type wholly aromatic
polyamide fiber
Technical Field
[OOOl]
This invention relates to a spun-dyed meta-type wholly
aromatic polyamide fiber. More specifically, this invention
relates to a spun-dyed meta-type wholly aromatic polyamide
fiber with small discoloration and fading due to the light
exposure.
Background Art
[ 0 0 0 2 ]
It is known that wholly aromatic polyamide fibers
produced from aromatic diamine and aromatic dicarboxylic
dihalide are excellent in the heat resistance and flame
resistance, and among such wholly aromatic polyamide fibers,
meta- type wholly aromatic polyamide fibers typified by
polymetaphenylene isophthalamide are known to be especially
useful as heat-resistant and flame-resistant fibers.
Furthermore, making use of these characteristics, meta-type
wholly aromatic polyamide fibers are preferably used in the
field of protective clothing such as a firefighter suit or a
heat-resistant work suit (please refer to PTL 1).
[ 0 0 0 3 ]
In the use in such clothing field, it is general to use
a dyed fiber . Further, as a method for obtaining a dyed fiber,
a piece-dyeing method for dyeing using a dye after producing
a fiber, or a spun-dyeing method for producing a fiber after
adding a pigment to a r a w spinning solution is known.
[ 0 0 0 4 I
Dyedmeta-typewhollyaromaticpolyamide fibers however,
aredisadvantageousinthatdiscolorationandfadingarecaused
by light irradiation, and the fibers cannot be sometimes used
depending on the degree of the discoloration and fading.
[ 0 0 0 5 ]
Therefore, regarding the piece-dyeingmethod for dyeing
using a dye, a method for preventing fading of a dyed meta-type
wholly aromatic polyamide fiber by adding a hindered amine
l i g h t stabilizer was proposed (please refer to PTL 2). W i t h
the method described in PTL 2 however, the decomposition of
a dye progresses by l i g h t irradiation for a long time, and the
discoloration- and fading-resistance for a long t i m e w a s not
satisfactory.
[00061
On the other hand, regarding the spun-dyeing method for
producing a fiber after adding a pigment to a raw spinning
solution, a method for kneading a yellow light fading coloring
agent towholly aromatic polyamide whichbecomes brownby light
irradiation for making the color light and preventing the
apparent discoloration and fading as well as prolonging the
time required for the discoloration was proposed (please refer
to PTL 3 ) . With the method described in PTL 3 however, the
effect is not enough in colors except for the yellow color,
and the method was not an ultimate solution.
Citation List
Patent Literature
[ 0 0 0 7 ]
PTL 1: JP-A-2006-016709
PTL 2: JP-A-2003-239136
PTL 3: JP-A-2-229281
Disclosure of Invention
Technical Problem
[00081
This invent ion was made in view of the above background
a r t , and an object thereof is to provide a spun-dyed meta-type
wholly aromatic polyamide fiber with small discoloration and
fading under the light exposure.
Solution to Problem
[0009]
The inventors studied extensively to solve the above
problems. As a result, the inventors found that, when the
content of the solvent remaining in the fiber is at a certain
level or lower, the discoloration and fading due to the light
exposure of the spun-dyed meta- type wholly aromatic polyamide
fiber obtained become smaller, and thus completed this
invention.
[ 0 0 10 ]
That is, this invention is a spun-dyed meta- type wholly
aromatic polyamide fiber which has a residual solvent content
of 0.1% by mass or less based on the whole mass of the fiber.
Advantageous E f f e c t s of Invention
[OOII]
The meta-type wholly aromatic polyamide fiber of this
invention becomes a spun-dyed meta-type wholly aromatic
polyamide fiber with small discoloration and fading due to the
light exposure. That is, in addition to the flame resistance
and heat resistance, which are original properties of a
meta-type wholly aromatic polyamide fiber, the meta-type
wholly aromatic polyamide fiber of this invention has a strong
point that the discoloration and fading of a product can be
preventedevenwhentheproductisusedunderthelightexposure
for a long time.
[00121
In addition, the spun-dyed meta-type wholly aromatic
polyamide fiber of this invention becomes a fiber with small
shrinkage at a high temperature and with excellent thermal
dimensional stability. Accordingly, it is possible to
continuously use the fiber stably also for applications with
the exposure to flame, the radiation heat or the like.
[0013]
Therefore, clothing made using the spun-dyed meta-type
wholly aromatic polyamide fiber according to this invention
exhibits excellent discoloration- and fading-resistance under
the light exposure for a long time and exhibits excellent
dimensional stability at a high temperature, and thus can be
preferably used for protective clothing such as a firefighter
suit or a heat-resistant work suit.
~escription of Embodiments
[0014]

The spun-dyed meta-type wholly aromatic polyamide fiber
of this invention has the following specific physical
properties. The physical properties, constitution,
production method and the like of the spun-dyed meta-type
whollyaromaticpolyarnide fiber ofthis inventionareexplained
below.
[0015]
[Physical Properties of Spun-Dyed Meta-Type Wholly Aromatic
Polyamide Fiber]
[Residual Solvent Content]
Ameta-type whollyaromatic polyamide fiber is generally
produced from a raw spinning solution in which a polymer is
dissolved in an amide solvent and a pigment is kneaded, and
thus the solvent naturally remains in the fiber. In the
spun-dyed meta-type wholly aromatic polyamide fiber of this
invention however, the content of the solvent remaining in the
fiber is 0.1% by mass or less based on the mass of the fiber.
It is essential that the content is 0.1% by mass or less and
it ismore preferable that the content is 0.08% bymass or less.
[0016]
When the solvent remains in the fiber in an amount
exceeding 0.1% by mass based on the mass of the fiber, the
residual solvent vaporizes during the processing or use under
a high temperature atmosphere exceeding 200°C, resulting in
inferior environmental safety. Further, such content is a
cause for the discoloration and fading of the fiber during the
use under the light exposure.
[0017]
In order to achieve the residual solvent content of the
fiber of 0.1% by mass or less, the components or the conditions
of the coagulation bath are adjusted so that a coagulated form
having no skin core is achieved and plasticized drawing is
conducted at a specific ratio, during the production steps of
the fiber.
[0018]
In this regard, "the residual solvent content of the
fiber" in this invention is a value obtained by the following
method.
(Method for Measuring Residual Solvent Content)
A fiber piece in an amount of 1.0 mg was collected and
the content of the amide solvent remaining in the fiber was
measured using gas chromatography (manufactured by Shimadzu
Corporation, model: GC-2010). Then, the residual solvent
concentration of the fiber w a s calculated from t h e standard
curve obtained using the amide solvent as the standard sample.
[0019]
[Maximum Thermal Shrinkage Rate]
Regarding the spun-dyed meta- type wholly aromatic
polyamide fiber of this invention, the maximum thermal
shrinkage rate under the rate of temperature increase of
100°C/minandthetemperature range of 25 to 500°Cispreferably
7.5%orless. Themaximumthermalshrinkagerateispreferably
7.5% or less, and more preferably 7.0% or less. When the
maximum thermal shrinkage rate exceeds 7 . 5 % , the dimension of
a product changes during the use under a high temperature
atmosphere, and a problem such as the breakage of a product
and the like arises, which is not preferable.
[0020]
In order to achieve the maximum thermal shrinkage rate
of the fiber of 7.5% or less, the components or the conditions
of the coagulation bath are adjusted so that a coagulated form
having no skin core is achieved, plasticized drawing is
conducted at a specific ratio and specific heat treatment is
conducted, during the production steps of the fiber.
[0021]
In this regard, "the maximum thermal shrinkage rate" in
t h i s invention is a value obtained by the following method.
(Method for Measuring Maximum Thermal Shrinkage Rate)
Thermal mechanical analyzer EXSTAR6000 manufactured by
SIT is used as the measurement device, a fiber sample is
separated in 480 dtex, and the fiber is pinched with a chuck
and used as a measurement sample. The shrinkage rate based
on the i n i t i a l fiber length of the sample at each temperature
is measured w i t h the following condition, and among the
shrinkage rate results obtained at each temperature, the
shrinkage rate at the temperature, at which the shrinkage rate
is the highest, is determined to be the maximum thermal
shrinkage rate.
(00221

Measurement sample length: 10 mm
R a t e of temperature increase: 100°C/min
Measurement temperature range: 25 to 500°C
Load applied on fiber sample: 1.2 cN
LO0231
[Lightness Index L*]
The lightness indexL* of the spun-dyedmeta-type wholly
aromatic polyamide fiber of this invention is not particularly
limited, andmaybeanycolor within the range inwhichcoloring
w i t h spun-dyeing is possible. Regarding the spun-dyed
meta-type wholly aromatic polyamide fiber of this invention
however, the effect is remarkable witha f i b e r w i t h a deep color.
Accordingly, the lightness index L* value of the f i b e r is
preferably 40 or less.
[0024]
[Light DiscolorationandFadingDegree (ColorDifference: AE*)
by Xenon Arc Fade Meter]
When the lightness index L* value is 40 or less, the
spun-dyed meta-type wholly aromatic polyamide fiber of this
inventionexhibits a color difference betweenbefore andafter
the irradiation with a xenon arc fade meter at 1.1 w/m2 for
80 hours, namelyalightdiscolorationandfadingdegree ( A E * ) ,
of 24.0 or less. The degree is preferably 23.0 or less, and
more preferably 22.0 or less. When the light discoloration
and fading degree (color difference: AE*) by a xenon arc fade
meter exceeds 2 4 . 0 , the discoloration and fading of the fiber
due to light irradiation is significant.
[00251
In t h i s regard, "the light discoloration and fading
degree (color difference : AE*) by a xenon arc fade meter" is
a value obtained by the following method.
(Determination Method for Light Discoloration and Fading
Degree (Color Difference: AE*) by Xenon A r c Fade Meter)
The light discoloration and fading degree (color
difference : AE*) by a xenon arc fade meter is measured using
unirradiated staple fiber and light-irradiated staple fiber
which has been irradiated with a xenon arc fade meter at 1.1
w/m2 for a certain time. First, the diffuse reflectance is
measured using an illurninant D65 with a field of -10 degrees,
and the lightness index L* value and the chromaticness indexes
a* and b* values are calculated by usual processing. The area
of the measurement light irradiation is 30 mm4. The light
discoloration and fading degree (color difference: AE*) is
d e t e r m i n e d by the following equation in accordance with JIS
2-8730 using the values obtained. In this regard, the light
discoloration and fading degree (color difference: AE*) by a
xenon arc fade m e t e r in t h i s invention was determined with the
irradiation time of 80 hours.
[Equation 11
AE* = ( (AL*) 2+ (Aa*) '+ (db*) 2 ,
LOO261
[Light Discolorationand Fading Degree (Color Difference: AE*)
by Carbon A r c Fade Meter]
When the lightness index L* value is 40 or less, the
spun-dyed meta-type wholly aromatic p o l y a m i d e fiber of t h i s
invention exhibits a color difference between before and after
the irradiation with a carbon arc fade m e t e r at 135 V and 17A
for 72 hours, namely a light discoloration and fading degree
(AE*) , of 2.5 or less. The degree is preferably 2 . 3 or less,
andmore preferably 2.1 or less. When the light discoloration
and fading degree (color difference : AE* ) by a carbon arc fade
meter exceeds 2 - 5 , the discoloration and fading of the fiber
due to light irradiation is significant.
[00271
In t h i s regard, "the light discoloration and fading
degree (color difference: AE*) by a carbon arc fade meter" is
a value obtained by the following method.
(Determination Method for Light Discoloration and Fading
Degree (Color Difference: AE*) by Carbon Arc Fade Meter)
The light discoloration and fading degree (color
difference : AE* ) by a carbon arc fade meter is measured using
unirradiated staple fiber and light-irradiated staple fiber
which has been irradiated with a carbon arc fade meter at 135
V and 17 A for a certain time, as the light discoloration and
fading degree (color difference : AE*) by a xenon arc fade meter
above. That is, the diffuse reflectance is first measured
using an illurninant D65 w i t h a f i e l d of -10 degrees, t h e
lightness index L* value and the chromaticness indexes a* and
b* values are calculated by usual processing, and the light
discoloration and fading degree is calculated by the above
equation in accordance with JIS 2-8730 using the values
obtained. The area of the measurement light irradiation here
is 10 mm4. In t h i s regard, the light discoloration and fading
degree (color difference: AE*) by a carbon arc fade meter in
this invention was determined with the irradiation time of 72
hours .
[00281
[ R a t i o of Light Discoloration and Fading Degree (Color
Difference: AE*) to Spun-Dyed Fiber Having High Residual
Solvent Content]
Regarding the spun-dyed meta-type wholly aromatic
polyamide fiber of t h i s invention, the light discoloration and
fading degree (color difference: AE*) between before and after
the irradiation w i t h a carbon arc fade meter at 135 V and 17
A for 72 hours is 75% or less of the light discoloration and
fading degree (color difference: AE*) of a spun-dyedmeta-type
wholly aromatic polyamide fiber having a residual solvent
content of the fiber of 0.4% by mass or more, in which the same
pigment is added in the same amount. The degree is preferably
72% or less, and more preferably 70% or less. When the ratio
ofthe light discolorationand fadingdegree (colordifference:
AE*) to that of a spun-dyed fiber of the same color having a
residual solvent content of 0.4% by mass or more exceeds 7 5 % ,
the discoloration and fading of the fiber due to light
irradiation is significant, which is not preferable.
[OOZ9]
In this regard, "the light discoloration and fading
degree (color difference: AE*) by a carbon arc fade meter" for
determining the ratio of the light discoloration and fading
degree (color difference: AE*) to that of a spun-dyed fiber
having a high residual solvent content is a value obtained by
conducting the same method as the method above with the
irradiation time of 72 hours.
t0030J
[Constitution of Meta-Type Wholly Aromatic Polyamidel
Themeta-typewhollyaromaticpolyamide constitutingthe
spun-dyed meta-type wholly aromatic polyamide fiber of this
invention is constituted by a meta-type aromatic diamine
component andameta-type aromatic dicarboxylic acidcomponent,
and another copolymerization component such as a component of
para-type m a y be copolymerized as long as the object of this
invention is not impaired.
100311
The component which is particularly preferably used as
the raw material for the spun-dyed meta-type wholly aromatic
polyamide fiber of this invention is meta-type whollyaromatic
polyamide containing a metaphenylene isophthalamide unit as
the main component, in view of the mechanical characteristics,
heat resistance and flame resistance.
[ 0 0 3 2 I
Regarding the meta-type wholly aromatic polyamide
constituted by a metaphenylene isophthalamide unit, the ratio
of the metaphenylene isophthalamide unit to all the repeating
units is preferably 90 mol% or more, more preferably 95 mol%
or more, and particularly preferably 100 mo10.
[00331
[Raw Materials for Meta-Type Wholly Aromatic Polyarnidel
(Meta-Type Aromatic Diamine Component)
As the meta-type aromatic diamine component serving as
the raw material for the meta-type wholly aromatic polyamide,
metaphenylene diamine, 3,4 -diaminodiphenyl ether,
3,4'-diaminodiphenylsulfone and the like, and derivatives
having a substituent such as halogen and an alkyl group having
1 to 3 carbon atom(s) on these aromatic rings, for example,
2,4-toluylenediamine, 2,6-toluylenediamine,
2,4-diaminochlorobenzene and 2,6-diaminochlorobenzene canbe
exemplified. Amongthem, metaphenylenediaminealoneormixed
diamine containing metaphenylene diamine in an amount of 85
mol% or more, preferably 90 mol% or more and particularly
preferably 95 mol% or more is preferable.
[ 0 0 3 4 I
(Meta-Type Aromatic Dicarboxylic Acid Component)
As the raw material for the meta-type aromatic
dicarboxylic acid component constituting the meta-type wholly
aromatic polyamide, for example, meta-type aromatic
dicarboxylic halide can be mentioned. As meta-type aromatic
dicarboxylic halide, isophthalic halides such as isophthalic
chloride and isophthalic bromide, and derivatives having a
substituent such as halogen and an alkoxy group having 1 to
3 carbon atoms on these aromatic rings, for example,
3-chloroisophthalic chloride can be exemplified. Among them,
isophthalic chloride alone, or mixed carboxylic halide
containingisophthalicchlorideinanamountof 85mol%ormore,
preferably 90 mol% or more and particularly preferably 95 mol%
or more is preferable.
[0035]
[Production Method for Meta-Type Wholly Aromatic Polyamide]
The production method for the meta-type wholly aromatic
polyamide constituting the spun-dyed meta-type wholly
aromatic polyamide fiber of this invention is not particularly
limited, and the meta-type wholly aromatic polyamide can be
produced for example by solutionpolymerizationor interfacial
polymerization using a meta-type aromatic diamine component
and a meta-type aromatic dicarboxylic chloride component as
raw materials.
to0361
In this regard, the molar weight of the meta- type wholly
aromatic polyamide is not particularly limited as long as a
fiber can be formed. In general, in order to obtain a fiber
with sufficient physical properties, a polymer having an
inherent viscosity (1.V-J measured in concentrated sulfuric
acid at a polymer concentration of 100 mg/100 mL sulfuric acid
at 30°C of 1.0 to 3 . 0 is appropriate, and a polymer having an
inherent viscosity of 1.2 to 2.0 is particularly preferable .
[00371

The spun-dyedmeta-type wholly aromatic polyamide fiber
of this invention can be produced using the meta-type wholly
aromatic polyamide obtainedbythe above productionmethodand
the like, and for example through the spinning solution
preparation step, spinning/coagulation step,
plasticized-drawing-bath drawing step, washing step,
relaxation treatment step and heat treatment step explained
below.
[0038]
[Spinning Solution Preparation Step]
In the spinning solutionpreparation step, the meta-type
wholly aromatic palyamide is dissolved in an amide solvent,
and a pigment is added thereto to prepare a spinning solution
(a spun-dyed meta-type wholly aromatic polyamide polymer
solution). In the preparationof a spinning solution, anamide
solvent is usually used, and as the amide solvent used,
N-methyl-2-pyrrolidone (NMP) , dimethylforrnamide (DMF) ,
dimethylacetamide (DMAc) and the like can be exemplified.
Among them, it is preferable to use NMP or DMAc in view of the
solubility and handling safety.
[00391
As the solution concentration, an appropriate
concentration may be appropriately selected in v i e w of the
coagulation rate i n the spinning/coagulation step as the
subsequent step and the s o l u b i l i t y of the polymer, and, when
the polymer is polymetaphenylene isophthalamide and the
solvent is NMP for example, it is usually preferable that the
concentration is within the range of 10 to 30% by mass.
[0040]
( Pigment )
As the pigment used i n t h i s invention, organic pigments
such as azo, phthalocyanine , perinone, perylene and
anthraquinone pigments, or inorganic pigments such as carbon
black, ultramarine, colcothar, titanium oxide and iron oxide
arementioned, butthepigment is not limitedtothesepigments.
[00411
As the method for mixing the meta- type wholly aromatic
polyamideandthepigment, amethodforforminganamide solvent
slurry in which the pigment is uniformly dispersed i n an amide
solvent and adding the amide solvent s l u r r y to a solution i n
which the meta- type wholly aromatic polyamide is dissolved i n
an amide solvent, a method for adding pigment powder directly
to a solution in which the meta-type wholly aromatic polyamide
is dissolved i n an amide solvent or the like is mentioned, but
themethod is notparticularlylimited. The spinning solution
thus obtained (a spun-dyedmeta-typewhollyaromatic polyamide
polymer solution) is formed into fibers, for example through
the following steps.
[0042]
(Pigment Content)
The pigment content is 10.0% by mass or less based on
the meta-type wholly aromatic polyamide, and preferably 5.0%
by mass or less. When more than 10.0% by mass of the pigment
is added, the physical properties of the fiber obtained
deteriorate, which is not preferable.
[0043]
[~pinning/~oagulatioSnt ep]
In the spinning/coagulation step, the spinning solution
obtained above (a spun-dyed meta-type wholly aromatic
polyamide polymer solution) is extruded into a coagulation
liquid and coagulated.
[0044]
The spinning apparatus is not particularly limited, and
a conventionally known wet-spinning apparatus can be used. In
addition, as long as stable wet spinning can be performed, it
is notnecessarytoparticularlylimit the spinninghole number,
arrangement state, hole shape and the like of a spinneret , and
for example, it is possible to use a multi-hole spinneret for
staple fibers in which the number of holes is 500 t o 3 0 , 0 0 0
and the spinning hole diameter is 0.05 to 0.2 mm and the like.
[00451
In addition, it is appropriate that the temperature of
the spinning solution (a spun-dyed meta-type wholly aromatic
polyamidepolymersolution) extrudedfromaspinneret is within
the range of 10 to 90°C.
[ 0 0 4 6 ]
As a coagulation bath used for obtaining the fiber of
this invention, an aqueous solution with an amide solvent
concentration of 45 to 60% bymass containing no inorganic salt
is used at a bath liquid temperature within the range of 10
to 35OC. An amide solvent concentration of less than 45% by
massleadstoastructurewithathickskin, andthus thewashing
efficiency in the washing step deteriorates and it becomes
difficult to achieve the residual solvent content of the fiber
obtained of 0.1% by mass or less. In addition, when the arnide
solvent concentration exceeds 60% by mass, coagulation that
is uniform even inside the fiber cannot be achieved, and thus
it becomes difficult to achieve the residual solvent content
of the fiber of 0.1% by mass or less. In this regard, it is
appropriate that the time of the fiber immersion in the
coagulation bath is within the range of 0.1 to 30 seconds.
LO0471
[Plasticized-Drawing-Bath Drawing Step]
In the plasticized-drawing-bath drawing step, while the
fiber obtained by coagulation in the coagulation bath is still
in the plasticized state, the fiber is subjected to drawing
treatment in a plasticized drawing bath.
100481
The plasticized drawing bath liquid is not particularly
limited and a conventionally known bath liquid can be used.
[004 91
In order to obtain the fiber of this invention, it is
necessary that the draw ratio in the plasticized drawing bath
is within the range of 3 . 5 to 5 . 0 times, and more preferably
within the range of 3.7 to 4.5 times. In the production of
the fiber used in this invention, by conducting plasticized
drawing with a specific draw ratio range in a plasticized
drawing bath, the removal of the solvent from the coagulated
fiber can be promoted and the residual solvent content of the
fiber of 0.1% by mass or less can be achieved.
[ O O S O ]
When the draw ratio in the plasticized drawing bath is
less than 3 . 5 times, the removal of the solvent from the
coagulated yarn becomes insufficient and it becomes difficult
to achieve the residual solvent content of the fiber of 0.1%
by mass or less. Further, the breaking tenacity becomes
i n s u f f i c i e n t and the handling duringtheprocessing steps such
as the spinning step becomes difficult. On the other hand,
when the draw ratio exceeds 5.0 times, the single-fiber
breakage occurs and the process stability deteriorates.
100511
The temperature of the plasticized drawing bath is
preferably within the range of 10 to 90°C. Preferably, when
the temperature is within the range of 20 to 90°c, the process
stability is excellent.
[0052]
[Washing Step]
In the washing step, the fiber drawn i n the plasticized
drawing bath is thoroughly washed. Washing affects the
quality of the fiber obtained and thus is preferably conducted
in several stages. In particular, the temperature of the
washingbathandtheamide solvent concentrationof thewashing
bath liquid in the washing step affect the extraction state
of the amide solvent from the fiber and the penetration state
ofwater i n t o t h e fiberfromthewashingbath. Therefore, also
forthepurposeof controllingtheminthemost suitablestates,
it is preferable that the washing step is in several stages
and the temperature condition and the concentration condition
of the amide solvent are controlled.
[ 0 0 5 3 I
The temperature condition and the concentration
condition of the amide solvent are not particularly limited
as longas the fiber finallyobtainedhas satisfactoryquality.
However, when the temperature of the first washing bath is as
high as 60°C or higher, water rapidly penetrates the fiber and
huge voids are thus formed in the fiber, resulting in the
deterioration of the quality. Accordingly, the temperature
o f t h e firstwashingbathispreferablyas lowas 3 0 ° C o r l o w e r .
[0054]
When the solvent remainsin the fiber, the environmental
safety in the processing of a product using the fiber and in
the use of a product formed using the fiber is not preferable.
Accordingly, the content of the solvent contained in the fiber
used in t h i s invention is 0.1% by mass or less, and m o r e
preferably 0.08% by mass or less.
[00551
[Dry-Heat Treatment Step]
In the dry-heat treatment step, the fiber after the
washing step is dried and heat-treated. The dry-heat
treatment method is not particularly limited, and for example,
amethodusingahotroller, ahotplateorthe likeismentioned.
Through dry-heat treatment, the spun-dyed meta-type wholly
aromatic polyamide fiber of this invention can be finally
obtained.
I00561
In order to obtain the fiber of this invention, the heat
treatment temperature in the dry-heat treatment step is
preferablywithintherangeof260t0350°C, andmorepreferably
within the range of 270 to 340°C. When the heat treatment
temperature is lower than 260°C, the crystallization of the
fiber is insufficient , and the shrinkage of the fiber becomes
large. On the other hand, when the temperature exceeds 350°C,
the crystallization of the fiber becomes too advanced and the
elongation at break deteriorates significantly. Further,
when the dry-heat treatment temperature is within the range
of 260 to 350°C, the maximum thermal shrinkage rate under the
rate of temperature increase of 10O0~/rnina nd the temperature
range of 25 to 500°C can be controlled to 7.5% or less, and
the breaking tenacity of the fiber obtained can be improved.
[00571
[Crimping Step and the like]
The spun-dyedmeta-type wholly aromatic polyamide fiber
after the dry-heat treatment may be further subjected to
crimpingprocessingif necessary. Further, a f t e r t h e crimping
processing, the fibermaybe cut inanappropriate fiber length
and subjected to the next steps. In addition, depending on
the case, the fiber may be reeled as a multifilament yarn.
Examples
[ 0 0 5 8 I
This inventionis explained further indetailbyExamples
and Comparative Examples below. In this regard, however,
these Examples and Comparative Examples are for a better
understanding of t h i s invention, and the scope of this
invention is not limited by these descriptions.
100591
Eachphysicalpropertyvalue of Examples andcomparative
Examples w a s measured by the following method.
[ 0 0 6 0 ]
[Inherent Viscosity (I.V.)]
Apolymerwasdissolvedin 97% concentratedsulfuricacid
and the inherent viscosity was measured a t 30°C using Ostwald
viscometer.
[00611
[Lightness Index L*]
The lightness index L* value was calculated by usual
processing after measuring the diffuse reflectance with an
illurninant D65 with a f i e l d of -10 degrees.
[0062]
[Fineness]
Based on JIS L1015, the corrected mass fineness was
measured in accordance with method A and represented by the
apparent fineness.
[00631
[Residual Solvent Content]
A fiber piece in an amount of 1.0 mg was collected and
the content of the amide solvent remaining i n the fiber was
measured using gas chromatography (manufactured by Shimadzu
Corporation, model: G C - 2 0 1 0 ) . Then, the residual solvent
concentration of the fiber was calculated from the standard
curve obtained using the amide solvent as the standard sample.
[ 0 0 6 4 I
[Maximum Thermal Shrinkage Rate]
Thermal mechanical analyzer EXSTAR6000 manufactured by
S I I is used as the measurement device, the fiber sample is
separated in 480 dtex, and the fiber is pinched with a chuck
and used as a measurement sample. The shrinkage rate based
on the initial fiber length of the sample at each temperature
was measured with the following condition, and among the
shrinkage rate results obtained at each temperature, the
shrinkage rate at the temperature, at which the shrinkage rate
was the highest, was determined to be the maximum thermal
shrinkage rate.
[DO651

Measurement sample length: 10 mm
Rate of temperature increase: 10O0~/rnin
Measurement temperature range: 25 to 500°C
Load applied on fiber sample: 1.2 cN
LOO661
[ ~ i g hDt iscolorationandFading~egree( ColorDifference: AE*)
by Xenon Arc Fade Meter]
Using unirradiated staple fiber and light-irradiated
staple fiber which had been irradiated w i t h a xenon arc fade
meter at 1.1 w/m2 for 24 hours and 80 hours, the d i f f u s e
reflectance w a s measured w i t h an illurninant D65 with a f i e l d
of -10 degrees, and the lightness index L* value and the
chromaticnessindexes a* andb*valueswere calculatedbyusual
processing. The area of the measurement light irradiation at
this timewas 30mm4. t he light discoloration and fa ding degree
(color difference: AE*) was determined by the following
equation in accordance with JIS 2 - 8 7 3 0 using the values
obtained.
[Equation 11
AE* = ( (AL*) '+ (Aa*) 2+ (Ab*) 2 ,
[ 0 0 6 7 ]
[Light DiscolorationandFadingDegree (ColorDifference: AE*)
by Carbon Arc Fade Meter]
Using unirradiated staple fiber and light-irradiated
staple fiber which had been irradiated w i t h a carbon arc fade
meter at 135 V and 17 A for 24 hours and 72 hours, the diffuse
reflectance w a s measured with an illuminant D65 with a field
of -10 degrees, and the lightness index L* value and the
chromaticnessindexes a* andb*valueswere calculatedbyusual
processing. The areaof themeasurement light irradiation at
thistimewas10mm~. Thelightdiscolorationandfadingdegree
(color difference: AE*) was determined by the same equation
as that of the light discoloration and fading degree (color
difference : AE* by a xenon arc fade meter above using the
values obtained.
[0068]
[Ratio of Light Discoloration and Fading Degree (Color
Difference: AE*)]
Using the light discoloration and fading degrees (AE*)
betweenbefore andafter the irradiationwitha carbonarc fade
meter at 135 V and 17 A for 72 hours, the proportion (%) of
an Example value to a value of Comparative Example having a
residual solvent content of the fiber of 0.4% by mass or more,
in which the same pigment was added in the same amount, was
calculated.
[0069]

[spinning Solution preparation Step]
In a reactor under dry nitrogen atmosphere, 72 1.5 parts
by mass of N, N-dimethylacetamide (DMAc) having a moisture
percentage of 100 ppm or less was weighed, 9 7 . 2 parts by mass
(50.18 mol%) of metaphenylene diamine was dissolved in this
DMAc, and the solution was cooled to O°C. To the cooled DMAc
solution, 181.3 parts by mass (49.82 mol%) of isophthalic
chloride (abbreviatedtoIPCbelow) was furtheraddedgradually
while the solutionwas stirred, andthepolymerizationreaction
was conducted.
[00701
N e x t , 66 - 6 parts by mass of calcium hydroxide powder
having an average particle size of 10 pm or less was weighed
and slowly added to the polymer solution after the completion
of the polymerization reaction, and the neutralization
reaction was conducted. After the addition of calcium
hydroxide was completed, the solution was further stirred for
40 minutes and a transparent polymer solution was obtained.
Polymetaphenylene isophthalamide was isolated from the
polymer solution obtained and the inherent viscosity (I.V.)
measured was 1.65. Further, the polymer concentrat ion of the
polymer solution w a s 17%.
[0071]
To this polymer solution, Pigment Blue 15 powder in a
ratio of 0.95% by mass based on the polymer was uniformly
dispersed, andaspinningsolution (spinningdope) wasproduced
by degassing under reduced pressure.
[ 0 0 7 2 ]
[Spinning/Coagulation Step]
The spinning dope above was discharged and spun from a
spinneret having a hole diameter of 0.07 mm and a hole number
of 500 into a coagulation bath having a bath temperature of
30°C. The compositionofthe coagulationliquidwaswater/DMAc
= 45/55 (parts by mass) and the discharging and spinning into
the coagulation bath was performed at a yarn speed of 7
m/minute .
[00731
[Plasticized-Drawing-Bath D r a w i n g Step]
Subsequently, drawing was performed at a draw r a t i o of
3 . 7 t i m e s in a p l a s t i c i z e d drawing bath at 4 0 ' ~ having a
composition of water/DMAc = 4 5 / 5 5 .
[0074]
[Washing Step]
After drawing, washing was performed in a bath of
water/DMAc = 70/30 at 20°C (immersion length: 1.8 m) and then
in a water bath at 20°C (immersion length: 3.6 m ) , followed
bythoroughwashingthroughawarmwaterbathat60°C (immersion
length: 5.4 m) .
[0075]
[Dry-Heat Treatment Step]
The fiber after washing was subjected to dry-heat
treatment using a hot roller having a surface temperature of
300°C, and a spun-dyed meta-type wholly aromatic polyamide
fiber was obtained.
100761
[Crimping and Cutting Step]
The fiberobtainedwas crimpedthrougha crimper andthen
cut with a c u t t e r into short fibers of 51 mm, and raw spun-dyed
meta-type whollyaromaticpolyamide staple fiber was obtained.
Each measurement result regarding the staple fiber obtained
is shown in Table 1.
[ 0 0 7 7 ]

Spun-dyed meta-type wholly aromatic polyamide staple
fiber was produced in the same manner as in Example 1, except
that a mixed pigment of Pigment Blue GO/pigment Black 7 (Navy
Blue) was used as the pigment. Each measurement result
regarding the staple fiber obtained is shown in Table 1.
[0080]

Spun-dyed meta-type wholly aromatic polyamide staple
f i b e r was produced in the same manner as in Example 2, except
that the composition of the coagulation liquid was changed to
water/DMAc (quantitative ratio) = 3 0 / 7 0 in the
spinning/coagulationstep. ~achmeasurementresultregarding
the staple fiber obtained is shown in Table 1.
[00811

Spun-dyed meta-type wholly aromatic polyamide staple
fiber was produced in the same manner as in Example 1, except
thatPigmentBlack7wasusedasthepigment. Eachmeasurement
result regarding the staple fiber obtained is shown i n Table
1.
[0082 I

Spun-dyed meta-type wholly aromatic polyamide staple
fiber was produced in the same manner as i n Example 3 , except
that the composition of the coagulation liquid was changed to
water/DMAc (quantitative ratio) = 3 0 / 7 0 in the
spinning/coagulationstep. Eachmeasurementresultregarding
the staple fiber obtained is shown i n Table 1.
LO083 I
[Table 11
Pigment Content (mass % )
Color
Lightness Index L*
Fineness (dtex)
Maximum Thermal Shrinkage
Rate (%)
Residual Solvent Content (%)
Example
1
0 . 9 5
Blue
34.7
1.91
6.3
0.08
11.9
20.0
2.40
69
Xenon A r c Fade
Meter
Evaluation
Arc
Fade Meter
Evaluation
AE* (24-hour
AE* (80-hour
irradiation)
AE* (24-hour
irradiation)
AE* (72-hour
irradiation)
Example AE*
/Cornpara t ive
Example AE*
I %
Comparative
Example 1
0.95
Blue
35.3
1.93
7.6
0.30
15.0
2 4 . 5
N o t
measured
N o t
measured
-
Comparative
Example 2
0.95
Blue
35.1
1.91
10.5
0.60
15.1
30.0
2.16
3.47
Example 2
0.95
Navy Blue
30.1
1.91
7.0
0.08
Not
measured
Not
measured
0.26
0.74
6 0
Comparative
Example 3
0.95
Navy Blue
30.0
1.94
8.8
0.41
Not
measured
Not
measured
0.43
1.23
-
Example 3
0.95
Black
28.6
1.92
7.1
0.09
Not
measured
Not
measured
0.34
0.49
4 2
Comparative
Example 4
0.95
Black
28.4
1.91
8 . 2
0.49
Not
measured
Not
measured
0.62
1.18
-
Industrial Applicability
[0084]
The fiberofthis inventionbecomesaspun-dyedmeta-type
wholly aromatic polyamide fiber, in which the discoloration
and fading of the fiber due to the light exposure for a long
time and the thermal shrinkage due to high temperature heating
such as the exposure to flame and the radiation heat are
prevented. Accordingly, the spun-dyed meta-type wholly
aromatic polyamide fiber of this invention can be used
preferablyfora firefighter suitor aheat-resistantworksuit
which requires these characteristics.

CLAIMS
[Claim 11
A spun-dyed meta-type wholly aromatic polyamide fiber,
wherein the residual solvent content is 0.1% by mass or less
based on the whole mass of the fiber.
[Claim 21
The spun-dyedmeta-type whollyaromatic polyamide fiber
according to c l a i m 1, wherein the color difference (AE*)
between before and after irradiation with a carbon arc fade
meter at 135 V and 17 A for 72 hours is 75% or less of the color
difference (AE* ) of a spun-dyed meta- type wholly aromatic
polyamide fiber having a residual solvent content of the fiber
of 0.4% by mass or more, in which the same pigment is added
in the same amount.
[Claim 31
The spun-dyedmeta-type wholly aromatic polyamide fiber
according to claim 1, wherein t h e color difference (AE*)
betweenbeforeandafter irradiationwithaxenonarc fademeter
at 1.1 w/m2 for 80 hours is 24.0 or less.
[ C l a i m 41
The spun-dyed meta-type wholly aromatic polyamide fiber
according to claim 1, wherein the color difference (AE*)
between before and after irradiation w i t h a carbon arc fade
meter at 135 V and 17 A for 72 hours is 2.5 or less.
[Claim 51
The spun-dyedmeta-type whollyaromatic polyamide fiber
according to any one of claims 1 to 4 , wherein the maximum
thermal shrinkage rate under a rate of temperature increase
of 100°C/min and a temperature range of 25 to 500'~ is 7.5% or
less.