JP2020045590A - Flame-retardant fabric containing meta-type wholly aromatic polyamide fiber - Google Patents

Abstract

To provide a flame-retardant fabric containing, as a component, a meta-type wholly aromatic polyamide fiber that has high fire retardancy, is safe, and is friendly to the environment, and that has a good durability capable of a long-term safety especially in protective clothing.SOLUTION: A flame-retardant fabric contains, as a component, a meta-type wholly aromatic polyamide fiber which contains an organophosphorus compound such that a phosphorus atom content in the meta-type wholly aromatic polyamide fiber is 0.2 wt.% or more, and which has a limiting oxygen index (LOI) on combustion of 33 or more, a strength retention of 90% or more after wet-heat treatment for 2 hours at 130°C, and a lightness L value of 85 or more.SELECTED DRAWING: None

Description

  The present invention relates to a fabric containing a meta-type wholly aromatic polyamide fiber, and more specifically, has a limiting oxygen index LOI at combustion of at least 33 or more, and a strength retention rate after wet heat treatment at 130 ° C. for 2 hours. Is a flame-retardant fabric having excellent durability and containing a meta-type wholly aromatic polyamide fiber having a lightness L value of 85% or more as a constituent component, and a residual flame time of 1 second or less. The present invention relates to a meta-type wholly aromatic polyamide fiber cloth having a flame retardancy of 1 second or less and a carbonization length of 5 cm or less.

  Conventionally, it is well known that a wholly aromatic polyamide produced from an aromatic diamine and an aromatic dicarboxylic acid dihalide has excellent heat resistance and flame retardancy, and these wholly aromatic polyamides are amide-based polar solvents. It is also well known that fibers can be formed from a polymer solution obtained by dissolving a wholly aromatic polyamide in the solvent by a method such as dry spinning, wet spinning, and semi-dry semi-wet spinning. Of these wholly aromatic polyamides, fibers of meta-type wholly aromatic polyamides (sometimes referred to as “metaramid”) represented by polymetaphenylene isophthalamide are particularly useful as heat-resistant and flame-retardant fibers. It is used in fields that exhibit these characteristics, for example, industrial applications such as filters and electronic components, and heat-resistant, flame-resistant, and disaster-prevention and safety clothing applications such as protective clothing in which flame resistance is important. . In recent years, not only industrial applications, but also applications to fields requiring aesthetics and visual properties such as bedding, clothing, interiors, etc. are rapidly expanding.

  In these fields, the flame retardancy of meta-type wholly aromatic polyamide fibers is required to be higher and more stable from the viewpoint of fire prevention and human life protection.

  In order to improve the flame retardancy of the meta-type wholly aromatic polyamide fiber, a method of adding an organic phosphorus compound, a phosphorus-containing phenol resin, a halogen compound, or the like to a polymer has been proposed. A method of improving the flame retardancy by blending has been proposed (see Patent Document 1 below). However, the compound used here, from the viewpoint of performing a stable fiber molding process, since a low molecular weight organic compound is used, there is a tendency that a part of the compound is discharged or dropped during the fiber molding process, In the case of halogen compounds, it is against recent trends in dehalogenation, which is concerned about environmental problems.

  On the other hand, meta-type wholly aromatic polyamide fibers generally use an amide-based organic solvent in the production process, and in this case, it is known that the amide-based solvent remains in the fiber. Therefore, the flame retardancy inherently possessed by the meta-type wholly aromatic polyamide cannot be sufficiently exerted, and only the poor flame retardancy is obtained (see Patent Documents 2 to 10 below). .

  Further, in order to improve the flame retardancy of the meta-type wholly aromatic polyamide fiber, it is preferable to reduce the amount of the residual solvent. 10% by weight of a layered clay mineral is contained, the amount of solvent remaining in the fiber is set to 1.0% or less, and the flame retardancy inherently possessed by the meta-type wholly aromatic polyamide is effectively exhibited. There has been proposed a method for obtaining a meta-type wholly aromatic polyamide fiber having a good flame-retardant effect without incorporating the same. However, there is a limit to improving the flame retardancy by this method, and it is necessary to add a flame retardant in order to give a higher performance, and the initial problem has not been sufficiently solved. Is the actual situation.

  Furthermore, it is known that many of the inexpensive flame retardants that are easy to add to the fiber are thermally decomposed at 160 ° C. to 300 ° C., so that decomposition starts at the stage of producing the fiber and a phosphoric acid component is generated. ing. For this reason, there has been a problem in that the amide bond portion of the meta-type wholly aromatic polyamide fiber is hydrolyzed in a moist heat state to decrease the strength.

JP-A-53-122817 Japanese Patent Publication No. 35-14399 JP-B-47-10863 JP-B-48-17551 JP-A-50-52167 JP-A-56-31009 JP-A-8-74121 JP-A-10-88421 JP 2000-303365 A JP 2001-348726 A JP 2007-254915 A

  The object of the present invention is to solve the problems in the prior art, and to show higher flame retardancy that is safer and more environmentally friendly, and to provide more secure flame retardancy for a long time, especially in protective clothing. Another object of the present invention is to provide a fabric containing a meta-type wholly aromatic polyamide fiber having excellent durability.

  The present inventor has conducted intensive studies in order to solve the above problems, and as a result, with respect to an organic solvent used for producing a meta-type wholly aromatic polyamide fiber, a flame retardant made of an organic phosphorus compound showing a specific dissolution behavior. Investigating that a meta-type wholly aromatic polyamide fiber having high flame retardancy can be obtained when the phosphorus atom content in the meta-type wholly aromatic polyamide fiber is 0.2 wt% or more, The present invention has been achieved by obtaining a fabric containing the fiber as a component.

That is, according to the present invention, there is provided a meta-type wholly aromatic polyamide fiber containing an organic phosphorus compound such that the phosphorus atom content in the meta-type wholly aromatic polyamide fiber is 0.2 wt% or more. A meta-type wholly aromatic polyamide fiber having a fiber critical oxygen index LOI of 33 or more, a strength retention of 90% or more after heat-moisture treatment at 130 ° C. for 2 hours and a lightness L value of 85 or more is used. Flame-retardant fabric, characterized by being a constituent component,
Is provided.

  According to the present invention, since the flame retardant composed of the organic phosphorus compound is uniformly mixed, the decrease in productivity such as yarn breakage in the fiber molding process is small, and the flame retardant is efficiently left in the fiber. It is possible to obtain a meta-type wholly aromatic polyamide fiber which can provide a flame-retardant effect by the added amount and does not have an effect such as corrosion of the apparatus when the coagulating liquid is reused.

Further, by using the organic phosphorus compound having a thermal decomposition initiation temperature of 300 ° C. or higher, the generation of components such as phosphoric acid in the fiber can be suppressed, so that the strength retention after the wet heat treatment at 130 ° C. for 2 hours is 90%. % Or more, and a meta-type wholly aromatic polyamide fiber excellent in durability can be obtained.
In addition, if a fabric containing the above-mentioned meta-type wholly aromatic polyamide fiber as a component is produced, a flame-retardant fabric having excellent flame retardancy and preventing deterioration in wet heat strength can be obtained.

  Hereinafter, the present invention will be described in detail.

  The meta-type wholly aromatic polyamide in the present invention is a polyamide produced by, for example, solution polymerization or interfacial polymerization using a meta-type aromatic diamine and a meta-type aromatic dicarboxylic acid halide as raw materials. May be copolymerized with another copolymerization component such as a para-type component within a range that does not inhibit the above.

  Examples of the meta-type aromatic diamine include metaphenylenediamine, 3,4′-diaminodiphenyl ether, 3,4′-diaminodiphenylsulfone and the like, and substituents such as halogen and alkyl groups having 1 to 3 carbon atoms on these aromatic rings. Such as 2,4-toluylenediamine, 2,6-toluylenediamine, 2,4-diaminochlorobenzene, and 2,6-diaminochlorobenzene. Among them, metaphenylenediamine or the above-mentioned mixed diamine containing 70% by mole or more of metaphenylenediamine is preferable.

  Further, as the meta-type aromatic dicarboxylic acid halide, isophthalic acid chloride, isophthalic acid halides such as isophthalic acid bromide, and derivatives having a substituent such as halogen, an alkoxy group having 1 to 3 carbon atoms on these aromatic rings, For example, 3-chloroisophthalic acid chloride and 3-methoxyisophthalic acid chloride can be used. Among them, isophthalic acid chloride or the above-mentioned mixed carboxylic acid halide containing isophthalic acid chloride in an amount of 70 mol% or more is preferable.

  Examples of copolymerizable components other than the above diamines and dicarboxylic acid halides include aromatic diamines, such as benzene derivatives such as paraphenylenediamine, 2,5-diaminochlorobenzene, 2,5-diaminobromobenzene, and aminoanisidine. , 1,5-naphthylenediamine, 4,4'-diaminodiphenylether, 4,4'-diaminodiphenylketone, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylmethane, and the like. Examples of the dicarboxylic acid halide include terephthalic acid chloride, 1,4-naphthalenedicarboxylic acid chloride, 2,6-naphthalenedicarboxylic acid chloride, 4,4′-biphenyldicarboxylic acid chloride, and 4,4′-diphenylether dicarboxylic acid chloride. .

  If the copolymerization ratio of these copolymerization components is too large, the properties of the meta-type wholly aromatic polyamide tend to deteriorate, so the content is preferably 20 mol% or less based on the total acid components of the polyamide. In particular, a preferred meta-type wholly aromatic polyamide is a polyamide in which 80 mol% or more of all repeating units are composed of metaphenylene isophthalamide units, and among them, polymetaphenylene isophthalamide is preferable.

  The meta-type wholly aromatic polyamide suitably has a degree of polymerization in which the intrinsic viscosity (IV) measured at 30 ° C. using 97% concentrated sulfuric acid as a solvent is in the range of 1.3 to 3.0.

  Next, the spinning dope is adjusted by dissolving the meta-type wholly aromatic polyamide obtained here in a solvent that dissolves the same, but it is also possible to use the spinning dope as it is without isolating the meta-type wholly aromatic polyamide after polymerization. . An amide solvent can be generally used as the solvent used here, and examples of main amide solvents include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc). can do. Among these, it is preferable to use NMP or DMAc from the viewpoint of solubility and handling safety.

  As the solution concentration, an appropriate concentration may be appropriately selected from the viewpoints of the coagulation rate and the solubility of the polymer in the next step of spinning and coagulation, for example, the polymer is polymetaphenylene isophthalamide and the solvent is NMP. In this case, it is usually preferable to set the range to 10 to 30% by mass.

  In the present invention, a flame retardant composed of an organic phosphorus compound is added to the spinning dope. In particular, a solvent having a property of dissolving at least 5% in the solvent of the spinning dope and not dissolving in a 60% aqueous solution of the solvent is used. By selecting and adding it, it is possible to dissolve it in the spinning dope and mix it uniformly, and the processing efficiency is high because the residual ratio in the fiber after the fiber forming processing is high.

  Here, when an organic phosphorus compound that is less than 5% soluble in the solvent is used, it becomes difficult to dissolve the necessary amount of the flame retardant in the spinning dope. Furthermore, in this case, it is necessary to uniformly disperse it in order to add it to the spinning dope, but it is a very difficult process when less than 5% is dissolved in the solvent. Even if the particles can be uniformly dispersed, the presence of particles or agglomerates of particles often causes problems such as breakage of single yarns during fiber molding, and the strength of the fibers decreases even if the fibers can be formed.

  In addition, those which dissolve in the solvent of the spinning dope at 5% or more and sufficiently dissolve in a 60% aqueous solution of this solvent also lose the flame retardant together with this solvent at the time of the fiber forming process. Otherwise, the performance cannot be exhibited, resulting in poor efficiency and inappropriate processing.

  The thermal decomposition onset temperature of the organic phosphorus compound is preferably 300 ° C. or higher, and more preferably 330 ° C. or higher. When the thermal decomposition initiation temperature is high, not only the flame retardancy due to the organic phosphoric acid compound is increased, but also the decomposition is suppressed during the heat treatment performed at the time of forming the fiber of the meta-type wholly aromatic polyamide. It is possible to obtain a meta-type wholly aromatic polyamide fiber excellent in durability, having a strength retention of at least 90% after heat treatment.

  Furthermore, by selecting a compound containing no halogen in the organic phosphorus compound, it is possible to cope with environmental problems.

  The flame retardant composed of the organic phosphorus compound used here was the above-mentioned feature among aromatic phosphate esters, aromatic condensed phosphate esters, halogen-containing phosphate esters, and halogen-containing condensed phosphate esters. Things can be selected. Particularly, aromatic condensed phosphoric acid esters which have a property of dissolving 5% or more in the solvent of the spinning dope and not dissolving in a 60% aqueous solution of this solvent are many, and mainly resorcinol bis- Diphenyl phosphate (RDP) resorcinol bis-dixylenyl phosphate (RDX) and the like can be used.

  However, many of the aromatic condensed phosphoric acid esters having the following structures are often in a liquid state at normal temperature, and are easily used in a 60% aqueous solution of a spin dope solvent and can be dissolved in 5% or more. Not preferred.

式中、Ｒは非ハロゲン化フェニル基、ＸはビスフェノールＡ残基、ｎは１〜３の整数を表す。
一方、下記構造式であらわされる芳香族縮合リン酸エステルは、常温で固体であり、本願の難燃剤として好ましい。

In the formula, R represents a non-halogenated phenyl group, X represents a bisphenol A residue, and n represents an integer of 1 to 3.
On the other hand, the condensed aromatic phosphate represented by the following structural formula is solid at ordinary temperature and is preferable as the flame retardant of the present invention.

式中、Ｒは非ハロゲン化フェニル基、Ｘは芳香環を有する構造で主に下記のものが好ましい。

In the formula, R is a non-halogenated phenyl group, and X is a structure having an aromatic ring, and the following are mainly preferred.

  Since the organic phosphorus compound is dissolved in an organic solvent used for producing the meta-type wholly aromatic polyamide fiber in an amount of 5% or more, it can be easily added to the spinning dope, and both the organic phosphorus compound and the meta-type wholly aromatic polyamide can be used. Since the fibers are uniformly mixed in the dissolved state, troubles such as breakage of single yarn during fiber forming are less likely to occur, and stable fiber production can be achieved.

  In addition, since the organic phosphorus compound has a property of being insoluble in a 60% aqueous solution of the organic solvent, it does not elute into the aqueous solution of the organic solvent, which is a coagulating liquid during fiber molding, and the efficiency is improved in the fiber. Because it remains well, the contribution to the development of flame retardancy is increased.

  Further, when the thermal decomposition onset temperature of the organic phosphorus compound is 300 ° C. or higher, decomposition by heat treatment performed at the time of fiber molding hardly occurs, and it is possible to obtain a fiber with little discoloration and low strength. Furthermore, by selecting a compound containing no halogen in the organic phosphorus compound, it is possible to cope with environmental problems.

  Next, the spinning dope prepared as described above is spun into a coagulating 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, arrangement state, hole shape, etc. of the spinneret need not be particularly limited as long as the spinning can be performed stably. For example, the number of spinning holes is 500 to 30,000, and the spinning hole diameter is 0.05. You may use a multi-hole spinneret or the like for a soup of up to 0.2 mm.

  Further, the temperature of the spinning dope when spinning from the spinneret is suitably in the range of 10 to 90 ° C.

  As an example of the coagulation bath used to obtain the fiber used in the present invention, an aqueous solution of an amide-based solvent containing no inorganic salt and having a concentration of 45 to 60% by mass is used at a bath solution temperature of 10 to 35 ° C. If the amide solvent concentration is less than 45% by mass, the skin has a thick structure, the washing efficiency in the washing step is reduced, and the solvent remains in the final fiber. When the amide-based solvent concentration exceeds 60% by mass, uniform coagulation cannot be performed even to the inside of the fiber, and therefore, many problems such as breakage of a single yarn during fiber forming processing occur. . The time for immersing the fibers in the coagulation bath is suitably in the range of 0.1 to 30 seconds.

  Next, while the fiber obtained by coagulation in the coagulation bath is in a plastic state, the fiber is drawn in a plastic drawing bath. The plastic stretching bath solution is not particularly limited, and a conventionally known bath solution can be employed.

  In order to obtain the fiber of the present invention, the draw ratio in the plastic stretching bath needs to be in the range of 3.5 to 5.0 times, and more preferably in the range of 3.7 to 4.5 times. . In the production of the fiber of the present invention, solvent removal from the coagulated yarn can be promoted by performing plastic stretching in a specific draw ratio range in a plastic stretching bath.

  When the stretching ratio in the plastic stretching bath is less than 3.5 times, the solvent removal from the coagulated yarn becomes insufficient. Further, the breaking strength becomes insufficient, and handling in a processing step such as a spinning step becomes difficult. On the other hand, if the stretching ratio exceeds 5.0 times, breakage of single yarns occurs, resulting in poor process stability.

  The temperature of the plastic stretching bath is preferably in the range of 10 to 90C. When the temperature is preferably in the range of 20 to 90 ° C., the process stability is good.

  Next, the solvent remaining in the fiber is washed. In this step, the fiber drawn in the plastic drawing bath is sufficiently washed. Washing is preferably performed in multiple stages because it affects the quality of the resulting fiber. In particular, the temperature of the washing bath in the washing step and the concentration of the amide-based solvent in the washing bath liquid affect the state of extraction of the amide-based solvent from the fibers and the state of water entering from the washing bath into the fibers. For this reason, it is preferable that the washing step is performed in multiple stages and the temperature condition and the concentration condition of the amide-based solvent are controlled, even for the purpose of setting these in an optimum state.

  The temperature condition and the concentration condition of the amide solvent are not particularly limited as long as the quality of the fiber finally obtained can be satisfied. However, if the temperature of the first washing bath is set to a high temperature of 60 ° C. or more, since water infiltrates into the fibers at once, huge voids are generated in the fibers, and the quality is deteriorated. For this reason, it is preferable that the temperature of the first cleaning bath is 30 ° C. or lower.

  When the solvent remains in the fiber, the flame retardancy of the fiber is reduced, and the processing of a product using the fiber and the environmental safety in using the product formed using the fiber are also preferable. Absent. For this reason, the amount of the solvent contained in the fiber used in the present invention is 0.2% or less, more preferably 0.15% or less, and particularly preferably 0.1% or less.

  Next, in the dry heat treatment step, the fiber that has undergone the cleaning step is dried and heat treated. The method of the dry heat treatment is not particularly limited, and examples thereof include a method using a hot roller, a hot plate, or the like. Through the dry heat treatment, the meta-type wholly aromatic polyamide fiber used in the present invention can be finally obtained.

  In order to obtain the fiber used in the present invention, the heat treatment temperature in the dry heat treatment step needs to be in the range of 260 to 350 ° C, and more preferably in the range of 270 to 340 ° C.

  When the heat treatment temperature is lower than 260 ° C., the crystallization of the fiber becomes insufficient, and the shrinkage of the fiber increases. On the other hand, when the temperature exceeds 350 ° C., the crystallization of the fiber becomes too large, so that the elongation at break is remarkably reduced. Further, setting the dry heat treatment temperature in the range of 270 to 340 ° C. contributes to improvement in the breaking strength of the obtained fiber.

  The meta-type wholly aromatic polyamide fiber that has been subjected to the dry heat treatment may be further crimped, if necessary. Furthermore, after crimping, the fiber may be cut into an appropriate fiber length and provided to the next step. In some cases, it may be wound as a multifilament yarn.

  The fabric of the present invention contains the above meta-type wholly aromatic polyamide fiber as a constituent component thereof. The content of the meta-type wholly aromatic polyamide fiber in the fabric is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass, based on the total mass of the fiber from the viewpoint of flame retardancy and texture. As described above, the content is particularly preferably 100%.

  In the fabric containing the meta-type wholly aromatic polyamide fiber of the present invention, as the fiber to be mixed with the meta-type wholly aromatic polyamide fiber, for example, polybenzimidazole fiber, polyimide fiber, polyamideimide fiber, polyetherimide fiber , Polyarylate fiber, polyparaphenylene benzobisoxazole fiber, novoloid fiber, flame retardant acrylic fiber, polyclar fiber, flame retardant polyester fiber, flame retardant cotton fiber, flame retardant wool fiber, para-type wholly aromatic polyamide fiber and the like. Among these, para-type wholly aromatic polyamide is preferable from the viewpoint of fiber strength and heat resistance.

  In the present invention, the form of the fabric may be any form of a woven fabric, a knitted fabric, or a nonwoven fabric.

When fibers other than the meta-type wholly aromatic polyamide fibers are included, for example, the fibers mixed with the meta-type wholly aromatic polyamide fibers are mixed by a conventional method to form a spun yarn, and then the spun yarn is used. To form a fabric.
The method for producing these fabrics is not particularly limited, and a known method can be employed.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by these examples.

  In the examples, “parts” and “%” are all based on mass unless otherwise specified, and the quantitative ratios indicate mass ratios unless otherwise specified. Each physical property value in Examples and Comparative Examples was measured by the following methods.

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

<Solubility evaluation>
Solubility evaluation was performed with two kinds of evaluation solutions.
(I) 100% of an organic solvent used for producing a meta-type wholly aromatic polyamide fiber,
(Ii) 60% aqueous solution of the organic solvent (organic solvent 60 / water 40)
The measurement was performed according to the following procedure.
(1) 5 g of the compound to be measured is added to a flask in which 100 g of the evaluation solution has been measured in advance, and the mixture is stirred at 20 ° C. for 2 hours.
(2) When undissolved residue is confirmed, the solution is left to stand at 20 ° C. for 12 hours or more, and when all the undissolved residue is dissolved, the solubility:> 5%.
(3) If residual undissolved is confirmed at this stage, 50 g of the supernatant is taken out into a weighing bottle, and the dissolution concentration is determined in% by weight by the absolute drying method.

<Fineness>
Based on JIS L1015, measurement based on the method A of the fineness of the fine weight was carried out, and the measurement was expressed in apparent fineness.

<Breaking strength, breaking elongation>
Based on JIS L1015, it measured on condition of the following using Instron model number 5565.

(Measurement condition)
Grip interval: 20mm
Initial load: 0.044 cN (1/20 g) / dtex
Tensile speed: 20 mm / min <Lightness L value / chromaticity b value>
It measured using the spectrocolorimeter SD7000 (made by Nippon Denshoku Industries).

<Flame retardant LOI value>
The LOI value was determined based on the LOI measurement method of JIS K7201.

<Thermal decomposition start temperature>
Thermogravimetric measurement was performed at a rate of 10 ° C./min using a Pyris 1 TGA (manufactured by PerkinElmer), and the temperature at which the sample weight decreased by 5% was defined as the pyrolysis onset temperature.

<Fabric flame retardancy>
Based on the flame retardancy measurement method of JIS L1091A-4, the afterflame time (second), the residual dust time (second), and the carbonization length (cm) were determined.

[Example 1]
(Production of polymer)
In a reaction vessel under a dry nitrogen atmosphere, 721.5 parts by mass of N, N-dimethylacetamide (DMAc) having a water content of 100 ppm or less are weighed, and 97.2 parts by mass of metaphenylenediamine (50.18 mol) is added to the DMAc. %) Was dissolved and cooled to 0 ° C. To the cooled DMAc solution, 181.3 parts by mass (49.82 mol%) of isophthalic acid chloride (hereinafter abbreviated as IPC) was further 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 the 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.

  From the obtained polymer solution, polymetaphenylene isophthalamide was isolated and measured for IV. As a result, it was 1.65. The polymer concentration in the polymer solution was 17%.

(Manufacture of spinning dope)
When the solubility of resorcinol bis-dixylenyl phosphate, which is an aromatic condensed phosphate ester, in DMAc was measured, the solubility was> 5%, and the solubility in a 60% aqueous solution of DMAc was 0%, which was insoluble. The thermal decomposition onset temperature of this compound was 320 ° C.

  This compound was added as a flame retardant to the polymer solution so as to have a phosphorus content of 0.50 wt% with respect to the polymer component, and decompressed under reduced pressure to obtain a spinning dope.

(spinning)
The above spinning dope was discharged from a spinneret having a hole diameter of 0.07 mm and a number of holes of 500 into a coagulation bath at a bath temperature of 30 ° C and spun. The composition of the coagulation solution was water / DMAc = 45/55 (parts by mass), and the coagulation solution was spun at a yarn speed of 7 m / min into a coagulation bath.

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

  After stretching, it 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 further washed with a 60 ° C warm water bath (immersion length 5 m). .4m) to sufficiently wash.

  After washing, dry heat treatment was performed with a hot roller having a surface temperature of 300 ° C., the fibers were bundled, passed through a crimper, crimped, and then cut with a cutter to obtain 51 mm short fibers, thereby obtaining raw cotton. . Using the obtained raw cotton, the flame retardancy LOI value was measured, indicating a high flame retardancy of 36.

  Further, a wet heat treatment was performed at 130 ° C. for 2 hours under saturated steam, and the breaking strength retention before and after the heat treatment was determined. Table 1 shows the results.

(Fabric production)
A spun yarn (count: 20/2) was prepared from the obtained raw cotton through a normal spinning process, and the spun yarn was woven into a 2/1 twill weave (basis weight: 280 g / m ² , thickness: 0.8 mm). ) Was prepared. The flame retardancy of the obtained woven fabric was as good as 0 seconds for residual flame, 0.7 seconds for dust, and 4.9 cm in carbonization length. Table 1 shows the results.

[Example 2]
Tinuvin 234, which is a benzotriazole ultraviolet absorber, was further added as a light-resistant stabilizer to the spinning dope produced in Example 1 so as to be 3.0 wt% with respect to the polymer component. The procedure was performed in the same manner as in Example 1 except that resorcinol bis-dixylenyl phosphate was added so that the phosphorus content was 0.75 wt% with respect to the polymer component, and the solution was depressurized to obtain a spinning dope.

  Although the LOI value of the raw cotton tends to decrease due to the addition of the ultraviolet absorber, it was maintained at a high value of 33 because the flame retardant of the present invention was added. Further, when the breaking strength retention rate of this raw cotton in a wet heat treatment at 130 ° C. for 2 hours under a saturated steam was determined, the strength was not reduced to 93%.

Further, a spun yarn (count: 20/2) was produced from the obtained raw cotton through a normal spinning process in the same manner as in Example 1, and a woven fabric (basis weight: 280 g / m ²⁾ was woven from the spun yarn into a 2/1 twill weave. , Thickness: 0.8 mm). The flame retardancy of the obtained woven fabric was as good as 0 seconds for afterflame time, 0.6 seconds for dust time, and 4.6 cm in carbonization length. Table 1 shows the results.

[Example 3]
A spun yarn (count: 20 /-) is prepared from the raw cotton obtained in Example 1 through a normal spinning process, and the spun yarn is knitted into a circular knitted fabric having a wool density of 40 / inch and a course density of 40 / inch. A knitted fabric (basis weight: 270 g / m ² , thickness: 0.75 mm) was produced.

  The flame retardancy of the obtained knitted fabric was good, with a residual flame time of 0 seconds, a residual dust time of 0.7 seconds, and a char length of 4.5 cm. Table 1 shows the results.

[Comparative Example 1]
After isolating polymetaphenylene isophthalamide from the polymer solution obtained according to the production of the polymer described in Example 1, it was dissolved in N-methyl-2-pyrrolidone (NMP), an amide solvent, so that the polymer concentration became 18%. Then, tinuvin 234, which is a benzotriazole ultraviolet absorber, was added as a light stabilizer to the polymer solution so as to have a concentration of 3.0 wt% with respect to the polymer component, and was uniformly dispersed. And Further, the same procedure as in Example 1 was carried out except that the composition of the coagulating liquid was changed to water / NMP = 70/30 (parts by mass), to obtain a raw cotton.

When the breaking strength retention of this raw cotton in a wet heat treatment at 130 ° C. for 2 hours under saturated steam was determined, the strength was not reduced to 97%, but the LOI value of the raw cotton was determined by the UV absorber and the organic pigment. , The value was as low as 24.
A spun yarn (count: 20/2) was produced from the obtained raw cotton through the usual spinning process in the same manner as in Example 1, and a woven fabric (basis weight: 280 ^g / m2) woven from the spun yarn into a 2/1 twill weave. ² , thickness: 0.8 mm). Regarding the flame retardancy of the obtained woven fabric, sufficient performance was not obtained because the afterflame time was 1.1 seconds, the dust time was 2.9 seconds, and the carbonization length was 6.3 cm. Table 1 shows the results.

[Comparative Examples 2 and 3]
In the polymer solution obtained in Comparative Example 1, although the solubility of the organic phosphorus compound in NMP is 5% or more, it is well soluble in a 60% aqueous solution of NMP (tris (chloropropyl) phosphate (thermal decomposition starting temperature: 160 ° C.)). Was performed in the same manner as in Comparative Example 1 except that phosphorus was added to the polymer component so as to have a phosphorus content of 0.47% by weight and 0.68%, and spin-doped by depressurization to obtain a raw cotton. In each spin dope, the chlorine content relative to the polymer component was 2.50%, 3.20%.

  The LOI values of these raw cottons were improved by the addition of the flame retardant from Comparative Example 1, and the flame retardancy was high at 33 and 37. However, the raw cotton was subjected to a wet heat treatment at 130 ° C. for 2 hours under saturated steam. When the breaking strength retention rates were determined, they were 86% and 77%, respectively, indicating a decrease in strength.

Further, a spun yarn (count: 20/2) was produced from the obtained raw cotton through a normal spinning process in the same manner as in Example 1, and a woven fabric (basis weight: 280 g / m ²⁾ was woven from the spun yarn into a 2/1 twill weave. , Thickness: 0.8 mm). Regarding the flame retardancy of the obtained woven fabric, the after-flame time was 0 seconds and 0 seconds, the dust time was 1.1 seconds and 0.8 seconds, and the carbonization length was 4.9 cm and 4.7 cm, respectively. Table 1 shows the results.

  According to the present invention, it is possible to obtain a fabric containing meta-type wholly aromatic polyamide fibers having the most suitable flame retardancy and durability for protective clothing, and the flame retardancy is reduced even when the protective clothing is worn for a long time. It is possible to provide a fibrous material that is a product that does not cause deterioration and has little progress in deterioration.

Claims (7)

  A meta-type wholly aromatic polyamide fiber containing an organic phosphorus compound such that the phosphorus atom content in the meta-type wholly aromatic polyamide fiber is 0.2 wt% or more, and the burning limit oxygen index LOI of the fiber Is a meta-type wholly aromatic polyamide fiber having a strength retention of 90% or more after wet heat treatment at 130 ° C for 2 hours or more and a lightness L value of 85 or more as its constituent component. Flame retardant fabric.   The flame-retardant fabric according to claim 1, wherein the thermal decomposition onset temperature of the organic phosphorus compound contained in the fiber is 300 ° C or higher.   The flame-retardant fabric according to claim 1 or 2, wherein the organic phosphorus compound is dissolved in an organic solvent used for producing the fiber in an amount of 5% or more and is insoluble in a 60% aqueous solution of the organic solvent.   The flame-retardant fabric according to any one of claims 1 to 3, wherein a halogen content in the fiber is 0.2 wt% or less.   The flame-retardant fabric according to any one of claims 1 to 4, wherein in the flame-retardant performance evaluation, the after-flame time is 1 second or less, the dust time is 1 second or less, and the carbonization length is 5 cm or less.   The flame-retardant fabric according to any one of claims 1 to 5, wherein the fabric is a knit.   The flame-retardant fabric according to any one of claims 1 to 5, wherein the fabric is a nonwoven fabric.