JP2015042790A - Stretch-broken spun yarn comprising spun-dyed meta-type wholly aromatic polyamide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretch-broken spun yarn comprising a spun-dyed meta-type wholly aromatic polyamide, which has low discoloration/fading when exposed to light.SOLUTION: The stretch-broken spun yarn is formed by using spun-dyed meta-type wholly aromatic polyamide fibers in which a content of a solvent remaining in the fiber is a set level or less. Specifically, the stretch-broken spun yarn is produced by using spun-dyed meta-type wholly aromatic polyamide fibers in which a content of a solvent remaining in the fiber is 0.1 mass% or less.

Description

  The present invention relates to an original meta type wholly aromatic polyamide check spun yarn. More specifically, the present invention relates to an original meta-type wholly aromatic polyamide check spun yarn having a small color change due to exposure.

It is known that wholly aromatic polyamide fibers produced from aromatic diamines and aromatic dicarboxylic acid dihalides are excellent in heat resistance and flame retardancy. Among these wholly aromatic polyamide fibers, polymetaphenylene isophthalate is known. Meta-type wholly aromatic polyamide fibers represented by amides are known to be particularly useful as fibers having excellent heat resistance and flame retardancy.
The spun yarn made of the meta-type wholly aromatic polyamide fiber is useful in various fields such as the industrial material field and the clothing field. For example, the spun yarn is suitably used in the field of protective clothing such as fire fighting clothes and heat-resistant work clothes. ing.

  As a method for producing the meta-type wholly aromatic polyamide spun yarn, for example, a check spinning method is used (see Patent Document 1). According to the check spinning method, it is not necessary to go through complicated steps such as crimping, cutting, cotton sacking, carding, kneading, roving, and rewinding, which are necessary in the conventional spun yarn manufacturing method. In addition, according to the method, since there is little influence of crimping and disorder of the orientation of the single yarn fiber, unlike conventional spun yarn, it has extremely low elongation, high strength, low crimp, and high creep resistance. A spun yarn having properties can be obtained.

By the way, in the garment field, which is the main use of spun yarn, it is common to use colored fibers because of demands such as design properties. As methods for obtaining colored fibers, there are known post-dyeing methods in which fibers are dyed and dyed with a dye, or original methods in which pigments are added to a spinning dope to make fibers.
However, the colored meta-type wholly aromatic polyamide fiber has a defect that it causes discoloration or discoloration by light irradiation for a short time, and there are applications that cannot be used depending on the degree of discoloration.

  Thus, as a post-dyeing method for dyeing with a dye, a method of adding a hindered amine light-resistant agent has been proposed in order to suppress the fading of the dyed meta-type wholly aromatic polyamide fiber (Patent Document). 2). However, the method described in Patent Document 2 has a problem that the degradation of the dye proceeds with long-term light irradiation, and the long-term resistance to discoloration is inferior.

  In addition, for the original deposition method in which pigment is added to the spinning dope and fiberized, a yellowish photo-fading colorant is kneaded into the wholly aromatic polyamide that turns brown by light irradiation, and the time until discoloration is obtained. A method has been proposed in which the color is faded for a long time and the apparent discoloration is suppressed (see Patent Document 3). However, in the method described in Patent Document 3, the effect is small for hues other than yellow, and has not been a fundamental solution.

JP-A-2-234932 JP 2003-239136 A JP-A-2-229281

  The present invention has been made in view of the above background art, and an object of the present invention is to provide an original meta-type wholly aromatic polyamide check spun yarn having a small color change under exposure.

  This inventor repeated earnest examination in order to solve said subject. As a result, if an original meta-type wholly aromatic polyamide fiber having a solvent content remaining in the fiber of a certain value or less is produced, and a spun yarn is formed using the fiber, the color change due to exposure is small. The present inventors have found that a spun yarn can be obtained and have completed the present invention. Specifically, a check spun yarn is formed using an original meta type wholly aromatic polyamide fiber having a residual solvent amount of 0.1% by mass or less in the fiber.

  That is, the present invention is a check spun yarn containing an original meta-type wholly aromatic polyamide fiber, and the residual solvent amount of the original meta-type wholly aromatic polyamide fiber is 0.1 mass relative to the entire fiber mass. % Is an original meta type wholly aromatic polyamide check spun yarn having a percentage of% or less.

  The original meta-type wholly aromatic polyamide check spun yarn of the present invention becomes a check spun yarn having a small color change due to exposure. In other words, in addition to the inherent properties of meta-type wholly aromatic polyamide fibers such as flame retardancy and heat resistance, the spun yarn has the advantage that it can suppress discoloration of the product even when used for a long time under exposure. Become.

Further, the check spun yarn of the present invention is a check spun yarn that has low shrinkage at high temperatures and excellent thermal dimensional stability. For this reason, stable use can be continued even in applications where flame exposure, radiant heat, or the like exists.
Therefore, the garment made using the check spun yarn according to the present invention exhibits excellent resistance to discoloration in long-time exposure and excellent dimensional stability at high temperatures. It can be suitably used as protective clothing such as sexual work clothes.

<Checked spun yarn made of original meta-type wholly aromatic polyamide fiber>
[Constituent fibers of check spun yarn]
The original meta-type wholly aromatic polyamide check spun yarn of the present invention contains an original meta-type wholly aromatic polyamide fiber described later as a main component. The content of the original meta-type wholly aromatic polyamide fiber in the check spun yarn is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100%.

  In addition, in the original meta type wholly aromatic polyamide check spun yarn of the present invention, the component contained in addition to the original meta type aromatic polyamide fiber is not particularly limited, and a fibrous, pulp-like component, etc. Can be raised. For example, polyolefin fibers, polyphenylene sulfide fibers, polyetherketone fibers, cellulose fibers, PVA fibers, polyester fibers, arylate fibers, liquid crystal polyester fibers, polyethylene naphthalate fibers and other organic fibers, glass fibers, rock wool, asbestos, boron fibers And inorganic fibers.

[Physical properties of original meta-type wholly aromatic polyamide check spun yarn]
[Light-changing chromaticity (color difference: ΔE *)]
When the lightness index L * value is 40 or less, the light-changing color of the original meta-type wholly aromatic polyamide check spun yarn of the present invention is irradiated with 1.1 W / m ² with a xenon arc fade meter around 80 hours. The checkered spun yarn has a color difference of 24.0 or less. It is preferably 23.0 or less, and more preferably 22.0 or less. When the light discoloration chromaticity (color difference: ΔE *) exceeds 24.0, the discoloration color of the check spun yarn due to light irradiation is remarkable, which is not preferable.

In the present invention, “light-changing chromaticity (color difference: ΔE *)” refers to a value obtained by the following method.
(How to determine the photochromic chromaticity (color difference: ΔE *))
The photochromic chromaticity (color difference: ΔE *) is determined using unirradiated check spun yarn and light irradiated check spun yarn irradiated at 1.1 W / m ² for a certain time with a xenon arc fade meter. First, the diffuse reflectance in a -10 degree visual field is measured using the light source D65, and the lightness index L * value, the chromaticness index a *, and the b * value are calculated by a normal calculation process. The measurement light irradiation area is 30 mmΦ. The light discoloration chromaticity (color difference: ΔE *) is obtained from the following equation using the obtained value in accordance with JIS Z-8730. The photochromic chromaticity (color difference: ΔE *) in the present invention was specified at an irradiation time of 80 hours.
[Formula 1]
ΔE * = ((ΔL *) ² + (Δa *) ² + (Δb *) ² ) ^1/2

<Original meta-type wholly aromatic polyamide fiber>
The original meta-type wholly aromatic polyamide fiber used in the present invention has the following specific physical properties. The physical properties, configuration, production method and the like of the original meta-type wholly aromatic polyamide fiber used in the present invention will be described below.

[Physical properties of original meta-type wholly aromatic polyamide fiber]
[Residual solvent amount]
Since the meta-type wholly aromatic polyamide fiber is usually produced from a spinning dope in which a polymer is dissolved in an amide solvent and a pigment is kneaded, the solvent necessarily remains in the fiber. However, the amount of the solvent remaining in the original meta-type wholly aromatic polyamide fiber used in the present invention 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 more preferably 0.08% by mass or less.

When the solvent remains in the fiber in excess of 0.1% by mass with respect to the fiber mass, the residual solvent volatilizes during processing and use in a high temperature atmosphere exceeding 200 ° C. Inferior to environmental safety. Further, when used under exposure, the residual solvent decomposes and causes discoloration of the fiber.
In order to reduce the amount of residual solvent in the fiber to 0.1% by mass or less, in the fiber manufacturing process, the components or conditions of the coagulation bath are adjusted so that the coagulation form does not have a skin core, and plasticization is performed at a specific magnification. Stretching is performed, and specific heat treatment is performed.

In the present invention, the “residual solvent amount in the fiber” refers to a value obtained by the following method.
(Measurement method of residual solvent amount)
About 8.0 g of fiber is collected, dried at 105 ° C. for 120 minutes, allowed to cool in a desiccator, and the fiber mass (M1) is weighed. Subsequently, this fiber is subjected to reflux extraction using a Soxhlet extractor in methanol for 1.5 hours to extract an amide solvent contained in the fiber. The fiber after extraction is taken out, vacuum-dried at 150 ° C. for 60 minutes, allowed to cool in a desiccator, and the fiber mass (M2) is weighed. The amount of solvent (amide solvent mass) N (%) remaining in the fiber is calculated by the following formula using M1 and M2 obtained.
[Formula 2]
N (%) = [(M1-M2) / M1] × 100

[Maximum heat shrinkage]
The original meta-type wholly aromatic polyamide fiber used in the present invention preferably has a maximum heat shrinkage of 7.5% or less at a temperature rising rate of 100 ° C./min and a temperature range of 25 to 500 ° C. It is preferably 7.5% or less, and more preferably 7.0% or less. If the maximum heat shrinkage rate exceeds 7.5%, the product dimensions change when used in a high-temperature atmosphere, and problems such as product breakage occur.

The “maximum heat shrinkage rate” in the present invention refers to a value obtained by the following method.
(Maximum heat shrinkage measurement method)
As a measuring device, a thermomechanical analyzer EXSTAR6000 made by SII is used, a fiber sample is divided into 480 dtex, and this is sandwiched between chucks and used as a measurement sample. The shrinkage rate with respect to the initial length of the sample fiber at each temperature is measured under the following conditions, and the shrinkage rate at the temperature at which the shrinkage rate is maximum among the obtained shrinkage rate results at each temperature is defined as the maximum heat shrinkage rate.
<Measurement conditions>
Measurement sample length: 10 mm
Temperature increase rate: 100 ° C./min
Measurement temperature range: 25-500 ° C
Load applied to fiber sample: 1.2 cN

[Light-changing chromaticity (color difference: ΔE *)]
The original meta-type wholly aromatic polyamide fiber used in the present invention has a color difference before and after irradiation for 80 hours at 1.1 W / m ² with a xenon arc fade meter, that is, a light change chromaticity (color difference: ΔE *) of 24. 0.0 or less. It is preferably 23.0 or less, and more preferably 22.0 or less. When the light discoloration chromaticity (color difference: ΔE *) exceeds 24.0, the discoloration of the fiber due to light irradiation is remarkable, which is not preferable.
Incidentally, the “photo-changeable chromaticity (color difference: ΔE)” of the original meta-type wholly aromatic polyamide fiber is the same as the photo-change coloration measurement of the above-mentioned original meta-type wholly aromatic polyamide fiber check spun yarn, The color difference of the fabric before and after irradiation for 80 hours at 1.1 W / m ² with a xenon arc fade meter is calculated based on JIS Z-8730.

[Configuration of meta-type wholly aromatic polyamide]
The meta-type wholly aromatic polyamide constituting the original meta-type wholly aromatic polyamide fiber used in the present invention is composed of a meta-type aromatic diamine component and a meta-type aromatic dicarboxylic acid component. Other copolymer components such as para type may be copolymerized within the range not impairing the purpose.

Particularly preferred as a raw material for the original meta-type wholly aromatic polyamide fiber used in the present invention is a meta-type mainly composed of a metaphenylene isophthalamide unit from the viewpoint of mechanical properties, heat resistance and flame retardancy. It is a wholly aromatic polyamide.
As the meta-type wholly aromatic polyamide composed of metaphenylene isophthalamide units, the metaphenylene isophthalamide units are preferably 90 mol% or more of the total repeating units, more preferably 95 mol% or more, particularly preferably. 100 mol%.

[Raw material for meta-type wholly aromatic polyamide]
(Meta-type aromatic diamine component)
Examples of the meta-type aromatic diamine component used as a raw material for the meta-type wholly aromatic polyamide include metaphenylene diamine, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfone, and the like, halogens in these aromatic rings, Examples of derivatives having a substituent such as an alkyl group having 1 to 3 carbon atoms, such as 2,4-toluylenediamine, 2,6-toluylenediamine, 2,4-diaminochlorobenzene, 2,6-diaminochlorobenzene, etc. can do. Of these, metaphenylenediamine alone or a mixed diamine containing metaphenylenediamine in an amount of 85 mol% or more, preferably 90 mol% or more, particularly preferably 95 mol% or more is preferable.

(Meta-type aromatic dicarboxylic acid component)
Examples of the raw material of the meta type aromatic dicarboxylic acid component constituting the meta type wholly aromatic polyamide include a meta type aromatic dicarboxylic acid halide. Examples of the meta-type aromatic dicarboxylic acid halide include isophthalic acid halides such as isophthalic acid chloride and isophthalic acid bromide, and derivatives having substituents such as halogen and alkoxy groups having 1 to 3 carbon atoms on the aromatic ring, such as 3 -Chloroisophthalic acid chloride etc. can be illustrated. Of these, isophthalic acid chloride itself or a mixed carboxylic acid halide containing isophthalic acid chloride in an amount of 85 mol% or more, preferably 90 mol% or more, particularly preferably 95 mol% or more is preferable.

[Method for producing meta-type wholly aromatic polyamide]
The production method of the meta-type wholly aromatic polyamide constituting the original meta-type wholly aromatic polyamide fiber used in the present invention is not particularly limited. For example, the meta-type aromatic diamine component and the meta-type aromatic dicarboxylic acid are used. It can be produced by solution polymerization or interfacial polymerization using an acid chloride component as a raw material.
The molecular weight of the meta-type wholly aromatic polyamide is not particularly limited as long as it can form fibers. In general, in order to obtain a fiber having sufficient physical properties, a polymer having an intrinsic viscosity (IV) measured in a concentrated sulfuric acid at 30 ° C. with a polymer concentration of 100 mg / 100 mL sulfuric acid is in a range of 1.0 to 3.0. Appropriate polymers in the range of 1.2 to 2.0 are particularly preferred.

<Method for Producing Original Meta-type Fully Aromatic Polyamide Fiber>
The original meta-type wholly aromatic polyamide fiber used in the present invention is prepared using the meta-type wholly aromatic polyamide obtained by the above production method, for example, a spinning solution preparation process, a spinning / coagulation process described below, It can be manufactured through a plastic stretching bath stretching step, a washing step, a relaxation treatment step, and a heat treatment step.

[Spinning liquid preparation process]
In the spinning solution preparation step, the meta-type wholly aromatic polyamide is dissolved in an amide solvent and a pigment is added to prepare a spinning solution (original meta-type wholly aromatic polyamide polymer solution). In preparing the spinning solution, an amide solvent is usually used, and examples of the amide solvent used include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc). be able to. Of these, NMP or DMAc is preferably used from the viewpoints of solubility and handling safety.
The concentration of the solution may be appropriately selected from the viewpoint of the coagulation rate and the solubility of the polymer in the next spinning and coagulation step. For example, the polymer is polymetaphenylene isophthalamide and the solvent is NMP. In the case of, it is usually preferred to be in the range of 10 to 30% by mass.

(Pigment)
Examples of the pigment used in the present invention include organic pigments such as azo, phthalocyanine, perinone, perylene, and anthraquinone, and inorganic pigments such as carbon black, ultramarine, bengara, titanium oxide, and iron oxide. However, it is not limited to these.
The mixing method of the meta type wholly aromatic polyamide and the pigment is to prepare an amide solvent slurry in which the pigment is uniformly dispersed in the amide solvent, and the meta type wholly aromatic polyamide is dissolved in the amide solvent. The method of adding to the solution, or the method of adding the pigment powder directly to the solution in which the meta-type wholly aromatic polyamide is dissolved in the amide solvent, is not particularly limited. The spinning solution thus obtained (original meta-type wholly aromatic polyamide polymer solution) is formed into a fiber through the following steps, for example.

(Pigment amount)
As a pigment compounding quantity, it is 10.0 mass% or less with respect to meta type wholly aromatic polyamide, Preferably it is 5.0 mass% or less. Addition of more than 10.0% by mass is not preferable because the physical properties of the resulting fiber are lowered.

[Spinning and coagulation process]
In the spinning / coagulation step, the spinning solution obtained above (original meta-type wholly aromatic polyamide polymer solution) is spun into a coagulation solution and coagulated.
The spinning device is not particularly limited, and a conventionally known wet spinning device can be used. Moreover, the number of spinning holes, the arrangement state, the hole shape and the like of the spinneret are not particularly limited as long as they can be stably wet-spun. For example, the number of holes is 500 to 30,000, and the spinning hole diameter is 0.05. A multi-hole spinneret for ˜0.2 mm sufu may be used.
Further, the temperature of the spinning solution (original meta-type wholly aromatic polyamide polymer solution) when spinning from the spinneret is suitably in the range of 10 to 90 ° C.

  As a coagulation bath for obtaining the fiber used in the present invention, an aqueous solution containing an amide solvent concentration of 45 to 60% by mass not containing an inorganic salt is used at a temperature of the bath solution of 10 to 35 ° C. If the amide solvent concentration is less than 45% by mass, the skin has a thick structure, the cleaning efficiency in the cleaning process is lowered, and it is difficult to make the residual solvent amount of the obtained fiber 0.1% by mass or less. In addition, when the amide solvent concentration exceeds 60% by mass, uniform solidification cannot be performed until reaching the inside of the fiber, and therefore, the residual solvent amount of the fibrils may be 0.1% by mass or less. It becomes difficult. In addition, the range of 0.1-30 seconds is suitable for the immersion time of the fiber in a coagulation bath.

[Plastic stretching bath stretching process]
In the plastic drawing bath drawing step, the fiber is drawn in the plastic drawing bath while the fiber obtained by coagulation in the coagulation bath is in a plastic state.
It does not specifically limit as a plastic drawing bath liquid, A conventionally well-known bath liquid can be employ | adopted.

  In order to obtain the fiber used in the present invention, the draw ratio in the plastic drawing bath needs to be in the range of 3.5 to 5.0 times, more preferably in the range of 3.7 to 4.5 times. And In the production of the fiber used in the present invention, the solvent removal from the coagulated yarn can be promoted by plastic drawing in a plastic drawing bath within a specific magnification range. It can be 1 mass% or less.

When the draw ratio in the plastic drawing bath is less than 3.5 times, the solvent removal from the coagulated yarn becomes insufficient, and it is difficult to reduce the residual solvent amount of the fibrils to 0.1% by mass or less. It becomes. Further, the breaking strength becomes insufficient, and handling in a processing process such as a spinning process becomes difficult. On the other hand, when the draw ratio exceeds 5.0 times, single yarn breakage occurs, resulting in poor process stability.
The temperature of the plastic stretching bath is preferably in the range of 10 to 90 ° C. Preferably process stability is good in the range of 20-90 degreeC of temperature.

[Washing process]
In the washing step, the fiber drawn in the plastic drawing bath is thoroughly washed. Washing is preferably performed in multiple stages because it affects the quality of the resulting fiber. In particular, the temperature of the cleaning bath in the cleaning step and the concentration of the amide solvent in the cleaning bath liquid affect the state of extraction of the amide solvent from the fibers and the state of penetration of water from the cleaning bath into the fibers. For this reason, it is preferable to control the temperature condition and the concentration condition of the amide solvent by setting the washing process in multiple stages for the purpose of bringing them into an optimum state.

  The temperature condition and the amide solvent concentration condition are not particularly limited as long as the quality of the finally obtained fiber can be satisfied. However, if the initial cleaning bath is set to a high temperature of 60 ° C. or higher, water enters the fiber at a stretch, and a huge void is generated in the fiber, resulting in deterioration of quality. For this reason, it is preferable that the first washing bath has a low temperature of 30 ° C. or lower.

  When the solvent remains in the fiber, environmental safety in processing of the product using the fiber and use of the product formed using the fiber is not preferable. For this reason, the amount of solvent contained in the fiber used in the present invention is 0.1% by mass or less, more preferably 0.08% by mass or less.

[Dry heat treatment process]
In the dry heat treatment step, the fiber that has undergone the washing step is dried and heat treated. Although it does not specifically limit as a method of dry heat processing, For example, the method of using a hot roller, a hot plate, etc. can be mentioned. By undergoing the dry heat treatment, the original meta-type wholly aromatic polyamide fiber used in the present invention can be finally obtained.

  In order to obtain the fiber used for this invention, it is necessary to make the heat processing temperature in a dry heat treatment process into the range of 260-350 degreeC, and it is more preferable to set it as the range of 270-340 degreeC. When the heat treatment temperature is less than 260 ° C., the fiber is insufficiently crystallized and the shrinkage of the fiber is increased. On the other hand, when it exceeds 350 ° C., the crystallization of the fiber becomes too large, and the elongation at break is significantly reduced. Moreover, making dry-heat-treatment temperature into the range of 260-350 degreeC contributes to the improvement of the breaking strength of the fiber obtained.

<Manufacturing method of check spun yarn made of original meta-type wholly aromatic polyamide fiber>
The original meta-type wholly aromatic polyamide check spun yarn of the present invention can be produced by a known method. That is, after checking the original meta-type wholly aromatic polyamide fiber (tow) obtained above, through the steps of imparting conjugation property and heat treatment, obtaining the original meta-type wholly aromatic polyamide check yarn Can do.

[Check-out process]
In order to obtain a check-spun spun yarn, first, a check-process is applied to the original meta-type wholly aromatic polyamide fiber (tow) that does not have crimps. A publicly known method can be adopted as a method for performing the check-out process. When checking the tow, it can be checked in a single step between a pair of supply rollers and a check roller, or can be checked in multiple steps.

[Conjugation imparting step]
Subsequently, conjugation is continuously imparted to the check yarn obtained above. As a method for imparting conjugation properties, for example, methods such as interlace treatment, fluff brazing treatment by swirling flow, and twisted yarn can be used alone or in combination. As an overfeed rate at the time of imparting conjugation property, it is preferable to maintain a tension state as 4% or less, and more preferably 3% or less. If conjugation is imparted in excess of 4%, the elongation of the check spun yarn obtained becomes too high and creep deformation increases, which is not preferable.

[Heat treatment process]
Subsequently, a check spun yarn can be obtained by heat treatment. The heat treatment method is not particularly limited, and a method of heat treatment after winding, a method of turning a heating roller a plurality of times, a method of running on a hot plate, and the like can be employed.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, these Examples and Comparative Examples are for helping understanding of the present invention, and the scope of the present invention is not limited by these descriptions.

<Measurement method>
Each physical property value in Examples and Comparative Examples was measured by the following method.

[Intrinsic viscosity (IV)]
The polymer was dissolved in 97% concentrated sulfuric acid and measured at 30 ° C. using an Ostwald viscometer.

[Fineness]
Based on JIS L1015, the measurement based on the A method of positive fineness was implemented, and it described with the apparent fineness.

[Residual solvent amount of fiber]
About 8.0 g of fiber was collected, dried at 105 ° C. for 120 minutes, allowed to cool in a desiccator, and the fiber mass (M1) was weighed. Subsequently, the fiber was subjected to reflux extraction using a Soxhlet extractor in methanol for 1.5 hours to extract an amide solvent contained in the fiber. The fiber after extraction was taken out, vacuum-dried at 150 ° C. for 60 minutes, allowed to cool in a desiccator, and the fiber mass (M2) was weighed. The amount of solvent (amide solvent mass) N (%) remaining in the fiber was calculated by the following formula using M1 and M2 obtained.
N (%) = [(M1-M2) / M1] × 100

[Maximum heat shrinkage of fiber]
As a measuring device, a thermomechanical analyzer EXSTAR6000 made by SII is used, a fiber sample is divided into 480 dtex, and this is sandwiched between chucks and used as a measurement sample. The shrinkage ratio with respect to the initial length of the sample fiber at each temperature was measured under the following conditions, and the shrinkage ratio at the temperature at which the shrinkage ratio was maximum among the obtained shrinkage ratio results at each temperature was defined as the maximum heat shrinkage ratio.
(Measurement condition)
Measurement sample length: 10 mm
Temperature increase rate: 100 ° C./min
Measurement temperature range: 25-500 ° C
Load applied to fiber sample: 1.2 cN

[Photo-changing chromaticity of fibers and check spun yarn with a xenon arc fade meter (color difference: ΔE *)]
Using a light irradiated cotton or light irradiated check spun yarn irradiated for 24 hours and 80 hours at 1.1 W / m ² with a xenon arc fade meter, the diffuse reflectance in a -10 degree field of view is measured with a light source D65. The lightness index L * value and the chromaticness index a *, b * value were calculated by ordinary arithmetic processing. The light discoloration chromaticity (color difference: ΔE *) was obtained from the following equation using the obtained value in accordance with JIS Z-8730.
[Formula 3]
ΔE * = ((ΔL *) ² + (Δa *) ² + (Δb *) ² ) ^1/2

<Example 1>
[Spinning liquid adjustment process]
In a reaction vessel under a dry nitrogen atmosphere, 721.5 parts by mass of N, N-dimethylacetamide (DMAc) having a moisture content of 100 ppm or less was weighed. %) Was dissolved and cooled to 0 ° C. To this cooled DMAc solution, 181.3 parts by mass (49.82 mol%) of isophthalic acid chloride (hereinafter abbreviated as IPC) was added while gradually stirring to carry out a polymerization reaction.
Next, 66.6 parts by mass of calcium hydroxide powder having an average particle size of 10 μm or less was weighed and slowly added to the polymer solution after completion of the polymerization reaction to carry out a neutralization reaction. After the addition of calcium hydroxide was completed, the mixture was further stirred for 40 minutes to obtain a transparent polymer solution. When polymetaphenylene isophthalamide was isolated from the obtained polymer solution and the intrinsic viscosity (IV) was measured, it was 1.65. The polymer concentration in the polymer solution was 17%.
In the polymer solution, Pigment Blue 15 powder having a polymer ratio of 0.95% by mass was uniformly dispersed and subjected to vacuum depressurization to prepare a spinning solution (spinning dope).

[Spinning and coagulation process]
The spinning dope was spun from a spinneret having a hole diameter of 0.07 mm and a number of holes of 1500 into a coagulation bath having a bath temperature of 30 ° C. The composition of the coagulation liquid was water / DMAc = 45/55 (parts by mass), and was spun by discharging into a coagulation bath at a yarn speed of 7 m / min.

[Plastic stretching bath stretching process]
Subsequently, the film was stretched at a stretching ratio of 3.7 times in a plastic stretching bath having a composition of water / DMAc = 45/55 at a temperature of 40 ° C.

[Washing process]
After stretching, the film was washed with a 20 ° C. water / DMAc = 70/30 bath (immersion length 1.8 m), followed by a 20 ° C. water bath (immersion length 3.6 m), and then a 60 ° C. hot water bath (immersion length 5). 4m) and thoroughly washed.

[Dry heat treatment process]
The washed fiber was subjected to a dry heat treatment with a heat roller having a surface temperature of 300 ° C. to obtain an original meta type wholly aromatic polyamide fiber. Table 1 shows various measurement results for the obtained fiber (uncrimped single yarn).

[Production of check spun yarn]
The tow of the obtained polymetaphenylene isophthalamide fiber was checked with a check ratio of 21 times between a pair of rollers at intervals of 600 mm to achieve single fiber convergence with an average fiber length of 230 mm, and continuously under the following conditions: A check spun yarn was obtained by imparting conjugability to. Table 1 shows various measurement results for the obtained spun yarn.
(Conjugation conditions)
Take-off nozzle pressure: 4 kg / cm ²
Conjugated nozzle pressure: 5 kg / cm ²
Yarn overfeed rate: 3.0%

<Comparative Example 1>
In the spinning / coagulation step, a preformed meta-type wholly aromatic polyamide check spun yarn was produced in the same manner as in Example 1 except that the composition of the coagulation liquid was changed to water / DMAc (quantity ratio) = 70/30. did. Table 1 shows various measurement results for the obtained uncrimped single yarn and check spun yarn.

<Comparative example 2>
In the spinning / coagulation step, a preformed meta-type wholly aromatic polyamide check spun yarn was produced in the same manner as in Example 1 except that the composition of the coagulation liquid was changed to water / DMAc (quantity ratio) = 30/70. did. Table 1 shows various measurement results for the obtained uncrimped single yarn and check spun yarn.

  According to the present invention, it is possible to provide an original meta type wholly aromatic polyamide check spun yarn in which discoloration due to long-time exposure and thermal shrinkage due to high-temperature heating such as flame exposure and radiant heat are suppressed. For this reason, the original meta type wholly aromatic check spun yarn of the present invention can be suitably used for fire fighting clothes and heat-resistant work clothes that require these characteristics.

Claims (3)

Checked spun yarn containing original meta-type wholly aromatic polyamide fiber,
The residual metal amount of the original meta-type wholly aromatic polyamide fiber is 0.1% by mass or less based on the entire fiber mass. An original meta-type wholly aromatic polyamide check spun yarn whose color difference (ΔE *) before and after irradiation for 80 hours at 1.1 W / m ² with a xenon arc fade meter is 24.0 or less.   2. The preformed meta type wholly aromatic polyamide fiber has a maximum heat shrinkage of 7.5% or less at a temperature rising rate of 100 ° C./min and a temperature range of 25 to 500 ° C. 2. Aromatic polyamide check spun yarn.