JP2021080586A - Easily dyeable meta type all aromatic polyamide fiber, and manufacturing method thereof - Google Patents

Abstract

To provide an easily dyeable meta type all aromatic polyamide fiber having excellent heat resistance, flame resistance, mechanical physical properties, etc., especially good dyeability while having high breaking strength.SOLUTION: An easily dyeable meta type all aromatic polyamide fiber comprises a meta type all aromatic polyamide having a weight-average molecular weight measured in accordance with JIS-K-7252 of 300,000-600,000, a breaking strength defined in JIS-L-1015 of 3.0 cN/dtex or over, a fiber crystallinity of 25% or over, and a dyeing rate of a dyed fiber of 90% or over.SELECTED DRAWING: Figure 1

Description

The present invention relates to a dyeable meta-type total aromatic polyamide fiber and a method for producing the same. More specifically, the break strength of the fiber is 3.0 cN / dtex or more, the crystallinity of the fiber is 25% or more, and the dyeing rate of the dyed fiber is 90% or more. And its manufacturing method.

It has been well known that all aromatic polyamides produced from aromatic diamines and aromatic dicarboxylic acid dihalides have excellent heat resistance and flame retardancy, and among such total aromatic polyamides, polymetaphenylene isophthalic acid The fibers of meta-type total aromatic polyamides represented by amides (hereinafter sometimes referred to as meta-aramids) are particularly useful as heat-resistant and flame-retardant fibers. By demonstrating these characteristics, it is used, for example, for disaster prevention and safety clothing such as protective clothing, and for industrial applications such as filters and electronic parts. Recently, applications in fields such as bedding, clothing, and interiors that make use of flame resistance and flame resistance are rapidly expanding. Especially in the clothing field, in addition to flame resistance and flame resistance, from the viewpoint of designability. Dyeability that allows the fiber color to be freely selected is also required as an important performance. However, the meta-type total aromatic polyamide fiber has a problem that it is difficult to dye by a usual method due to its rigid polymer molecular chain.

Therefore, as a method for improving dyeability, a method has been proposed in which a meta-aromatic polyamide fiber that is easily dyed with a cationic dye is obtained by adding an onium salt of alkylbenzene sulfonic acid to the spinning solution (Patent Documents). 1). According to this method, a meta-aromatic polyamide fiber having good dyeability can be obtained for a cationic dye. However, the fiber to which the onium salt is added has a high cost.

In another report, the dye is contained throughout the fiber structure by forming amorphous fibers with pores, steam heating the fibers swollen with water, and diffusing the dye into the pores of the fibers. The fibers were subsequently steam-heated at a temperature higher than the glass transition temperature for a sufficient period of time to crush the pores, thereby irreversibly confining the dye in the fibers and causing the fibers. Has been proposed (Patent Document 2).

According to this method, fibers having good dyeability can be obtained, but not only heat treatment using high-temperature steam is required, but also the physical characteristics of the fibers before the treatment are too low to withstand practical use. Therefore, there is a possibility that fiber crystallization may be insufficient even after the above treatment. In general, it is known that a low crystallinity of all aromatic polyamide fibers causes a decrease in strength, shrinkage under high temperature conditions or dyeing treatment, and a decrease in dimensional stability.

On the other hand, in Japanese Patent Application Laid-Open No. 3 and Patent Document 4, the components or conditions of the coagulation bath are appropriately adjusted so as to form a coagulation form without a skin core, plastically stretched at a specific magnification, subjected to a washing step, and then 260 to 330 degrees. A method for obtaining a meta-total aromatic polyamide fiber having high dyeability has been proposed by performing a dry heat treatment in the above. According to this method, crystallization is completed by dyeing the fibers crystallized in the range of 5 to 20% so as not to affect the dyeability, and the physical properties of the fibers are secured.

However, the above crystallinity is insufficient to exhibit heat resistance and low thermal shrinkage, assuming that the raw fiber before the dyeing treatment is used. That is, if it is assumed that the raw fiber is processed according to the purpose and the textile product is manufactured, it is necessary to handle it on the premise of dyeing treatment, which narrows the range of use of the fiber.

Japanese Unexamined Patent Publication No. 08-081827 Japanese Unexamined Patent Publication No. 62-184127 Japanese Unexamined Patent Publication No. 2010-08423 Japanese Unexamined Patent Publication No. 2011-236543

An object of the present invention is to solve the problems in the prior art, and to use a meta-type total aromatic polyamide fiber having excellent properties such as heat resistance, flame retardancy, and mechanical properties, while having a particularly high breaking strength. It is an object of the present invention to provide an easily dyeable meta-type total aromatic polyamide fiber having good dyeability.

As a result of diligent studies to solve the above problems, the present inventor skillfully controls the weight average molecular weight of the meta-type total aromatic polyamide and uses a wet spinning method using a high-concentration inorganic salt coagulation liquid. As a result, it has been found that a meta-type total aromatic polyamide fiber having good fiber breaking strength and good dyeability can be obtained while increasing the crystallinity of the fiber, and has completed the present invention.

That is, according to the present invention.
1. 1. It is made of meta-type total aromatic polyamide with a weight average molecular weight of 300,000 to 600,000 measured according to JIS-K-7252, has a breaking strength of 3.0 cN / dtex or more specified in JIS-L-1015, and is a fiber. Easy-dyeing meta-type total aromatic polyamide fiber, which has a crystallinity of 25% or more and a dyeing rate of dyed fiber of 90% or more.
as well as,
2. An amide system having a weight average molecular weight of 300,000 to 600,000, measured according to JIS-K-7252, having a concentration of 10 to 30% by mass of a meta-type total aromatic polyamide and an inorganic salt concentration of 0.1 to 10% by mass. A method for producing a total aromatic polyamide fiber by wet-spinning a polar solvent solution, wherein the amide-based polar solvent solution is aqueous-coagulated containing 30% by mass or more of an inorganic salt and 3% by mass or more of an amide-based solvent. A method for producing an easily dyeable meta-type total aromatic polyamide fiber, which comprises a step of spinning in a bath to solidify and heat-setting at a temperature of 300 ° C. or higher.
Is provided.

According to the present invention, a meta-type total aromatic polyamide fiber having high fiber crystallinity, good fiber breaking strength, and good dyeability can be obtained. Therefore, when the fiber is used for clothing. , A textile product having a desired design can be easily obtained by a dyeing treatment. In addition, since the raw fiber before the dyeing treatment also has a high degree of crystallinity, it fully exerts its function as a meta-type total aromatic polyamide fiber, and the possibility that its use is limited is reduced.

It is sectional drawing which illustrates an example of the easy-dyeing meta-type total aromatic polyamide fiber of this invention. It is sectional drawing which illustrates an example of the easy-dyeing meta-type total aromatic polyamide fiber of this invention. It is sectional drawing which illustrates an example of the easy-dyeing meta-type total aromatic polyamide fiber of this invention. It is sectional drawing which illustrates one example of the meta-type total aromatic polyamide fiber of the comparative example.

Hereinafter, the present invention will be described in detail.

The meta-type total aromatic polyamide (hereinafter sometimes referred to as meta-aramid) constituting the meta-type total aromatic polyamide fiber of the present invention is composed of a meta-type aromatic diamine component and a meta-type aromatic dicarboxylic acid component. Other copolymerization components such as para-type may be copolymerized as long as the object of the present invention is not impaired.

Particularly preferably used in the present invention is a meta-type total aromatic polyamide containing a metaphenylene isophthalamide unit as a main component from the viewpoint of mechanical properties, heat resistance, and flame retardancy. The meta-type total aromatic polyamide composed of metaphenylene isophthalamide units preferably contains 90 mol% or more of all repeating units, more preferably 95 mol% or more, and particularly preferably 95 mol% or more. It is 100 mol.

Examples of the meta-aromatic diamine component used as a raw material for the meta-type total aromatic polyamide include metaphenylenediamine, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfone, and halogens on these aromatic rings. Derivatives having a substituent such as an alkyl group having 1 to 3 carbon atoms, for example, 2,4-toluylene diamine, 2,6-toluylene diamine, 2,4-diaminochlorobenzene, 2,6-diaminochlorobenzene and the like are exemplified. can do. Among them, it is preferable that it is a mixed diamine containing only meta-phenylenediamine or 85 mol% or more, preferably 90 mol% or more, particularly preferably 95 mol% or more of meta-phenylenediamine.

Examples of the raw material of the meta-aromatic dicarboxylic acid component constituting the meta-type total aromatic polyamide include meta-aromatic dicarboxylic acid halide. Examples of the meta-aromatic dicarboxylic acid halide include isophthalic acid halides such as isophthalic acid chloride and isophthalic acid bromide, and derivatives having a substituent such as a halogen or an alkoxy group having 1 to 3 carbon atoms in these aromatic rings, for example, 3. − Chlorisophthalic acid chloride and the like can be exemplified. Among them, 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.

As a method for polymerizing the metaaramid, an organic solvent system (for example, tetrahydrofuran) containing metaphenylenediamine and isophthalic acid chloride, which is not a good solvent, is brought into contact with an aqueous solution system containing an inorganic acid acceptor and a soluble neutral salt. By this method, a method for isolating a powder of a polymetaphenylene isophthalamide polymer (Japanese Patent Publication No. 47-10863), or solution polymerization of the above diamine and acid chloride with an amide solvent and then using calcium hydroxide, calcium oxide, etc. Examples of the method for neutralizing (Japanese Patent Laid-Open No. 8-074121, Japanese Patent Application Laid-Open No. 10-88421) and the like can be mentioned, but the method is not limited thereto.

The weight average molecular weight of the metaaramid used in the present invention is 300,000 to 60, according to the analysis method described later, from the viewpoint of being able to form fibers having high crystallinity, good breaking strength, and good dyeability. It needs to be a polymer in the range of 10,000.

That is, the easily dyeable meta-type total aromatic polyamide fiber of the present invention has a weight average molecular weight of 400,000 to 600,000 in order to obtain a fiber having a breaking strength of 3.0 cN / dtex or more and a dyeing rate of 90% or more. A range of polymers is needed.

As the polymer having the molecular weight specified in the present invention, a mixture of a low molecular weight polymer and a high molecular weight polymer can also be used, and the total molecular weight may be a desired value by adjusting the mixing ratio. For example, when a polymer having a weight average molecular weight of 200,000 and a polymer having a weight average molecular weight of 800,000 are mixed and the total weight average molecular weight is 500,000, there is no problem in using the polymer in the present invention.

On the other hand, when the molecular weight is less than 300,000, a fiber having strength cannot be obtained. Further, if the molecular weight exceeds 600,000, fibers having a dyeing rate of 90% or more cannot be obtained.

The meta-type total aromatic polyamide fiber of the present invention uses the meta-aramid polymer obtained by the above production method, for example, a spinning solution preparation step, a spinning / coagulation step, a washing step, a boiling water drawing step, which will be described below. Manufactured through a dry heat treatment process and a heat stretching process.

In the spinning solution preparation step, the metaaramid polymer is dissolved in a solvent to prepare a spinning solution (dope). In the preparation of the spinning solution, an amide solvent is usually used, and N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like can be exemplified. Among these, it is preferable to use NMP or DMAc from the viewpoint of solubility and handling safety.

The solution concentration is preferably in the range of 10 to 30% by mass, preferably in the range of 15 to 25% by mass, from the viewpoint of the solidification rate in the next step of spinning and solidification and the solubility of the polymer. Is more preferable.

In the present invention, it is necessary to introduce an inorganic salt into the dope, and in order to obtain a fiber having a dyeing rate of 90% or more, it is necessary to contain an inorganic salt of 0.1 to 20% by mass with respect to the dope, which is stable. In order to obtain the desired spinnability, 0.1 to 10% by mass of an inorganic salt is more preferable.

Here, if an inorganic salt exceeding 20% by mass is contained, the solidification rate becomes too high, and a large number of voids are formed in the fiber, so that the fiber having the desired physical characteristics cannot be obtained. As the inorganic salt, it is preferable to use a chloride salt such as calcium chloride, magnesium chloride, or lithium chloride.

In the spinning / coagulation step, the dope obtained above is spun into a coagulation liquid and coagulated. The spinning device is not particularly limited, and a conventionally known wet spinning device can be used. The number of spinning holes and the arrangement state of the spinneret do not need to be particularly limited as long as they can be stably wet-spun. For example, staples having 10 to 30,000 holes and a spinning hole diameter of 0.03 to 0.2 mm. A multi-hole spinneret for fibers or the like may be used. The dope temperature when spinning from the spinneret is preferably in the range of 20 to 90 ° C, but is particularly preferably 70 to 90 ° C.

The coagulation bath used to obtain the fibers of the present invention contains 30% by mass or more, preferably 35 to 45% by mass of an inorganic salt such as calcium chloride or magnesium chloride, and 1 to 20% by mass, preferably an amide solvent. An aqueous solution containing 3 to 15% by mass is used in the range of 50 to 90 ° C.

The coagulated yarn thus obtained is sufficiently washed with water in an aqueous washing bath and sent to a boiling water drawing step. The stretching ratio in the boiling water stretching bath is preferably 1.5 to 5.0 times, more preferably 2.0 to 4.0 times. In the present invention, the strength of the finally obtained fiber can be ensured by stretching within the range of the magnification and increasing the molecular chain orientation.

A dry heat treatment step is preferably performed on the fibers that have undergone the washing / stretching step. In the dry heat treatment step, the fibers washed by the above washing step are subjected to dry heat treatment in a range of preferably 100 to 250 ° C., more preferably 100 to 200 ° C. Here, the dry heat treatment is not particularly limited, but is preferably performed under a fixed length. The temperature of the above-mentioned dry heat treatment refers to the set temperature of the fiber heating means such as a hot plate and a heating roller.

In the present invention, the fiber that has undergone the dry heat treatment step is subjected to a heat drawing step. In the heat stretching step, stretching is performed while applying heat treatment at 300 to 380 ° C. The draw ratio is preferably 1.2 to 5.0 times, more preferably 1.5 to 4.0 times. Subsequently, a heat setting step is performed to perform sufficient crystallization. In the dry heat treatment step, the heat-stretched fibers are heat-set, preferably in the range of 300 or more ° C., more preferably 300 to 400 ° C. Here, the heat setting treatment is not particularly limited, but is preferably performed under a fixed length. The temperature of the above heat setting process refers to the set temperature of the fiber heating means such as a hot plate and a heating roller.

The breaking strength of the meta-type total aromatic polyamide fiber obtained by the above method is 3.0 cN / dtex or more, and the crystallinity is 25% or more. The breaking strength is required to be 3.0 cN / dtex or more, and 3.5 cN / dtex or more is particularly preferable. The degree of crystallinity is indispensable to be 25% or more, preferably in the range of 25 to 40%. When the breaking strength or the crystallinity is less than the above, problems such as inferior mechanical properties of the fiber hindering the process passability and lowering the durability of the product in more advanced applications occur.

The dyeing rate of the dyed fiber of the meta-type total aromatic polyamide fiber obtained by the above method is 90% or more, preferably 92% or more, and more preferably 95%. If the dyeing rate is 90% or less, there are problems in the dyeing process, such as being unable to dye the desired hue unfavorably in terms of aesthetics required in the clothing field, and requiring a lot of dyes and processing time. Occurs.

As shown in FIGS. 1 to 3, the cross-sectional shape of the fiber of the present invention is preferably C-shaped (also referred to as U-shaped). When the cross-sectional shape of the fiber is C-shaped (also referred to as U-shaped), the surface area is large and the dyeing rate is good. In addition, it is expected to exhibit functionality such as sweat absorption when used for clothing.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the following contents. Each physical property value in Examples and Comparative Examples was measured by the following method.

[Weight average molecular weight Mw]
Analysis was performed by a high performance liquid chromatography device equipped with a column for size exclusion chromatography according to JIS-K-7252, and measurement was performed using dimethylformamide (containing 0.01 mol% lithium chloride) as the developing solvent. .. As the standard molecular weight sample, a polystyrene set manufactured by Sigma-Aldrich (peak top molecular weight Mp = 400 to 2000000) was used.

[Single fiber fineness]
The measurement was carried out in accordance with JIS-L-1015 and in accordance with the method A of positive fineness, and the apparent fineness was expressed.

[Breaking strength, breaking elongation]
Measurement was performed under the following conditions based on JIS-L-1015 using a tensile tester (manufactured by Instron, model: 5565).
(Measurement condition)
Grab interval: 20 mm
Initial load: 0.044cN (1 / 20g / dtex)
Tensile rate: 20 mm / min

[Dyeing rate]
The "dyeing" for obtaining the "dyeing rate" is dyeing by the following dyeing method.
(Dyeing method)
Cationic dye (manufactured by Nippon Kayaku Co., Ltd., trade name: Kayacryl Blue GSL-ED (B-54)) 6% owf, acetic acid 0.3 mL / L, sodium nitrate 20 g / L, benzyl alcohol 70 g / L as a carrier agent, dispersion A dyeing solution containing 0.5 g / L of a dyeing aid (manufactured by Meisei Chemical Industry Co., Ltd., trade name: disper TL) is prepared as an agent.

Subsequently, the dyeing treatment is carried out at 120 ° C. for 60 minutes with the bath ratio of the fiber to the dyeing solution being 1:40. After the dyeing treatment, a treatment liquid containing 2.0 g / L of hydrosulfite, 2.0 g / L of amylazine D (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: amylazine D), and 1.0 g / L of sodium hydroxide. The dyed fibers are obtained by performing reduction washing at a bath ratio of 1:20 at 80 ° C. for 20 minutes, washing with water, and then drying.

The "dyeing rate" in the present invention means a value obtained by the following method.
Dichloromethane in the same volume as this dyeing residual liquid is added to the dyeing residual liquid obtained by dyeing the raw fibers, and the residual dye is extracted. Subsequently, the absorbances of the extracts at wavelengths of 670 nm, 540 nm, and 530 nm were measured, and the dye concentrations of the extracts were obtained from the calibration curves of the above three wavelengths prepared from a dichloromethane solution having a known dye concentration in advance. The average value of the concentrations is defined as the dye concentration (C) of the extract. Using the dye concentration (Co) before dyeing, the value obtained by the following formula is defined as the dyeing rate (U).
Dyeing rate (U) = [(Co-C) / Co] x 100

[Crystallinity]
The pre-dyed fibers (raw fibers) were bundled in a bundle having a diameter of about 1 mm, and converted from the profile obtained by measuring with an X-ray diffraction measuring device (trade name: RIGAKU RINT TTRIII) under the following conditions.
(Measurement condition)
X-ray source: Cu-Kα ray Fiber sample table: 50 rpm rotation 2θ scanning: 5-50 °
Continuous measurement: 0.1 °
Width measurement: 1 ° / min scanning

Specifically, air scattering and non-coherent scattering were corrected by linear approximation from the measured diffraction profile to obtain a total scattering intensity profile. The undried yarn profile of the meta-type total aromatic polyamide fiber, which is amorphous, was visually fitted to the obtained total scattering intensity, and the difference was defined as the crystal scattering intensity. The crystallinity was calculated from the following formula using the area (integral value) of the crystal scattering intensity and the total scattering intensity.
Crystallinity (%) = (Crystal Scattering Intensity Area / Total Scattering Intensity Area) x 100

[Example 1]
A metaaramid polymer powder having a weight average molecular weight of 470,000 and calcium chloride powder synthesized by solution polymerization and washed with water and purified were dissolved in N-methyl-2-pyrrolidone (NMP) to obtain a transparent polymer solution. At this time, the mass concentration of the metaaramid polymer was adjusted to 20% and the calcium chloride content was adjusted to 2.5% with respect to the polymer solution.

This polymer solution was heated to 85 ° C. and used as a spinning stock solution, which was discharged from a spinning spout having a hole diameter of 0.1 mm and a number of holes of 2000 into a coagulation bath at 83 ° C. for spinning. The composition of this coagulation bath is 38% by mass of calcium chloride, 5% by mass of NMP, 57% by mass of the remaining water, and passes through at a thread speed of 7.8 m / min at an immersion length (effective coagulation bath length) of 140 cm. After letting it, it was once pulled out into the air.

The coagulated yarn was washed with water in the first to third water washing baths, and the total immersion time at this time was 360 seconds. The first to third aqueous washing bath temperatures were 20, 30, and 50 ° C., respectively. Next, the washing yarn was stretched 3.0 times in boiling water at 90 ° C., and subsequently immersed in warm water at 90 ° C. for 50 seconds for washing.

Next, it was wound around a roller having a surface temperature of 170 ° C. and subjected to dry heat treatment, and then stretched 1.5 times on a hot plate having a surface temperature of 340 ° C. Finally, a meta-type total aromatic polyamide fiber was obtained by heat-setting for 5 seconds under a constant length on a hot plate having a surface temperature of 320 ° C.

The obtained fibers had a fineness of 2.2 dtex, a strength of 3.1 cN / dtex, an elongation of 88%, and a crystallinity of 28%. The cross-sectional shape of the fiber was C-shaped (also referred to as U-shaped). A scanning electron microscope image of the obtained fiber cross section is shown in FIG. The dyeing rate after the dyeing treatment was 99% or more.

[Example 2]
A metaaramid polymer powder having a weight average molecular weight of 520,000 and calcium chloride powder synthesized by solution polymerization and washed with water and purified were dissolved in N-methyl-2-pyrrolidone (NMP) to obtain a transparent polymer solution. At this time, the mass concentration of the metaaramid polymer was adjusted to 20% and the calcium chloride content was adjusted to 0.2% with respect to the polymer solution.

This polymer solution was heated to 85 ° C. and used as a spinning stock solution, which was discharged from a spinning spout having a hole diameter of 0.1 mm and a number of holes of 2000 into a coagulation bath at 80 ° C. for spinning. The composition of this coagulation bath is 38% by mass of calcium chloride, 5% by mass of NMP, 57% by mass of the remaining water, and passes through at a thread speed of 7.8 m / min at an immersion length (effective coagulation bath length) of 140 cm. After letting it, it was once pulled out into the air.

The coagulated yarn was washed with water in the first to third water washing baths, and the total immersion time at this time was 360 seconds. The first to third aqueous washing bath temperatures were 20, 30, and 50 ° C., respectively. Next, the washing yarn was stretched 3.0 times in boiling water at 90 ° C., and subsequently immersed in warm water at 90 ° C. for 50 seconds for washing.

Next, it was wound around a roller having a surface temperature of 170 ° C. and subjected to dry heat treatment, and then stretched 1.5 times on a hot plate having a surface temperature of 320 ° C. Finally, a meta-type total aromatic polyamide fiber was obtained by heat-setting for 5 seconds under a constant length on a hot plate having a surface temperature of 310 ° C.

The obtained fibers had a fineness of 2.2 dtex, a strength of 3.2 cN / dtex, an elongation of 59%, and a crystallinity of 31%. The cross-sectional shape of the fiber was C-shaped (also referred to as U-shaped). A scanning electron microscope image of the obtained fiber cross section is shown in FIG. The dyeing rate after the dyeing treatment was 91%.

[Example 3]
A metaaramid polymer powder having a weight average molecular weight of 530,000 and calcium chloride powder synthesized by interfacial polymerization and washed with water and purified were dissolved in NMP to obtain a transparent polymer solution. At this time, the mass concentration of the metaaramid polymer was adjusted to 20% and the calcium chloride content was adjusted to 1.0% with respect to the polymer solution.

This polymer solution was heated to 85 ° C. and used as a spinning stock solution, which was discharged from a spinning spout having a hole diameter of 0.1 mm and a number of holes of 2000 into a coagulation bath at 83 ° C. for spinning. The composition of this coagulation bath is 38% by mass of calcium chloride, 5% by mass of NMP, 57% by mass of the remaining water, and passes at a thread speed of 7.8 m / min at an immersion length (effective coagulation bath length) of 180 cm. After letting it, it was once pulled out into the air.

The coagulated yarn was washed with water in the first to third water washing baths, and the total immersion time at this time was 360 seconds. The first to third aqueous washing bath temperatures were 20, 30, and 50 ° C., respectively. Next, the washing yarn was stretched 2.2 times in boiling water at 90 ° C., and subsequently immersed in warm water at 90 ° C. for 50 seconds for washing.

Next, it was wound around a roller having a surface temperature of 170 ° C. and subjected to dry heat treatment, and then stretched 2.0 times on a hot plate having a surface temperature of 340 ° C. Finally, a meta-type total aromatic polyamide fiber was obtained by heat-setting for 5 seconds under a constant length on a hot plate having a surface temperature of 320 ° C.

The obtained fibers had a fineness of 2.0 dtex, a strength of 3.4 cN / dtex, an elongation of 76%, and a crystallinity of 28%. The cross-sectional shape of the fiber was C-shaped (also referred to as U-shaped). A scanning electron microscope image of the obtained fiber cross section is shown in FIG. The dyeing rate after the dyeing treatment was 99% or more.

[Comparative Example 1]
A metaaramid polymer having a weight average molecular weight of 720,000 synthesized by solution polymerization was dissolved in NMP to obtain a transparent polymer solution. At this time, the mass concentration of the metaaramid polymer was adjusted to 22% with respect to the polymer solution.

The polymer solution was spun in the same manner as in Example 1 to obtain meta-type total aromatic polyamide fibers.

The obtained fibers had a fineness of 2.1 dtex, a strength of 4.6 cN / dtex, an elongation of 50%, and a crystallinity of 34%. The cross-sectional shape of the fiber was Mayu-shaped. A scanning electron microscope image of the obtained fiber cross section is shown in FIG. The dyeing rate after the dyeing treatment was 66%.

[Comparative Example 2]
A metaaramid polymer powder having a weight average molecular weight of 720,000 and calcium chloride powder synthesized by solution polymerization were dissolved in NMP to obtain a transparent polymer solution. At this time, the mass concentration of the metaaramid polymer was adjusted to 22% and the calcium chloride content was adjusted to 2.5% with respect to the polymer solution.

This polymer solution was spun in the same manner as in Example 1 to obtain meta-type total aromatic polyamide fibers.

The obtained fibers had a fineness of 2.1 dtex, a strength of 4.6 cN / dtex, an elongation of 45%, and a crystallinity of 40%. The cross-sectional shape of the fiber was C-shaped (also referred to as U-shaped). The dyeing rate after the dyeing treatment was 70%.

[Comparative Example 3]
A metaaramid polymer powder having a weight average molecular weight of 520,000 synthesized by interfacial polymerization was dissolved in NMP to obtain a transparent polymer solution. At this time, the mass concentration of the metaaramid polymer was adjusted to 22% with respect to the polymer solution.

This polymer solution was spun in the same manner as in Example 2 to obtain meta-type total aromatic polyamide fibers.

The obtained fibers had a fineness of 2.2 dtex, a strength of 3.3 cN / dtex, an elongation of 55%, and a crystallinity of 30%. The cross-sectional shape of the fiber was Mayu-shaped. The dyeing rate after the dyeing treatment was 74%.

Table 1 shows the physical characteristics of the meta-type total aromatic polyamide fibers obtained in Examples and Comparative Examples.

When the easily dyeable meta-type total aromatic polyamide fiber of the present invention is used for clothing, a fiber product having a desired design can be easily obtained by a dyeing treatment. In addition, since the raw fiber before the dyeing treatment also has a high degree of crystallinity, it fully exerts its function as a meta-type total aromatic polyamide fiber, and the possibility that its use is limited is reduced.

Further, the production method of the present invention has a low viscosity of the polymer used, so that the operability is improved. In addition, stable production can be performed because it is a method of giving high-strength solidified yarn without strict control of spinning conditions, and its industrial value is extremely large.

Claims (4)

It is made of meta-type total aromatic polyamide with a weight average molecular weight of 300,000 to 600,000 measured according to JIS-K-7252, has a breaking strength of 3.0 cN / dtex or more specified in JIS-L-1015, and is a fiber. An easily dyeable meta-type total aromatic polyamide fiber having a crystallinity of 25% or more and a dyeing rate of 90% or more measured by the following method of dyed fibers.
(Dyeing method)
Cationic dye (manufactured by Nippon Kayaku Co., Ltd., trade name: Kayacryl Blue GSL-ED (B-54)) 6% owf, acetic acid 0.3 mL / L, sodium nitrate 20 g / L, benzyl alcohol 70 g / L as a carrier agent, dispersion A dyeing solution containing 0.5 g / L of a dyeing aid (manufactured by Meisei Chemical Industry Co., Ltd., trade name: disper TL) is prepared as an agent.
Subsequently, the dyeing treatment is carried out at 120 ° C. for 60 minutes with the bath ratio of the fiber to the dyeing solution being 1:40. After the dyeing treatment, a treatment liquid containing 2.0 g / L of hydrosulfite, 2.0 g / L of amylazine D (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: amylazine D), and 1.0 g / L of sodium hydroxide. The dyed fibers are obtained by performing reduction washing at a bath ratio of 1:20 at 80 ° C. for 20 minutes, washing with water, and then drying.
Dichloromethane in the same volume as this dyeing residual liquid is added to the dyeing residual liquid obtained by dyeing the raw fibers, and the residual dye is extracted. Subsequently, the absorbances of the extracts at wavelengths of 670 nm, 540 nm, and 530 nm were measured, and the dye concentrations of the extracts were obtained from the calibration curves of the above three wavelengths prepared from a dichloromethane solution having a known dye concentration in advance. The average value of the concentrations is defined as the dye concentration (C) of the extract.
Using the dye concentration (Co) before dyeing, the value obtained by the following formula is defined as the dyeing rate (U).
Dyeing rate (U) = [(Co-C) / Co] x 100 The easily dyeable meta-type total aromatic polyamide fiber according to claim 1, wherein the fiber crystallinity is 25 to 40%. The easily dyeable meta-type total aromatic polyamide fiber according to claim 1 or 2, wherein the elongation at break specified in JIS-L-1015 is 40 to 90%. An amide system having a weight average molecular weight of 300,000 to 600,000, measured according to JIS-K-7252, having a concentration of 10 to 30% by mass of a meta-type total aromatic polyamide and an inorganic salt concentration of 0.1 to 10% by mass. A method for producing a total aromatic polyamide fiber by wet-spinning a polar solvent solution, wherein the amide-based polar solvent solution is aqueous-coagulated containing 30% by mass or more of an inorganic salt and 3% by mass or more of an amide-based solvent. A method for producing an easily dyeable meta-type total aromatic polyamide fiber, which comprises a step of spinning in a bath to solidify and heat-setting at a temperature of 300 ° C. or higher.

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