JP2014105403A - Method for producing para-type whole aromatic copolyamide fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a para-type whole aromatic copolyamide fiber, which can produce a para-type whole aromatic copolyamide fiber having high tensile modulus, and has superior process stability.SOLUTION: The production method comprises the steps of: opening a raw material of the para-type whole aromatic copolyamide fiber; and then subjecting the raw material to heat treatment under tension at a tension and temperature of a specific range.

Description

  The present invention relates to a method for producing para-type wholly aromatic copolyamide fibers. More specifically, the present invention relates to a method for producing a para-type wholly aromatic copolyamide fiber having a high tensile elastic modulus.

Para-type wholly aromatic copolyamide fibers are excellent in tensile strength and elastic modulus, and are also excellent in heat resistance and chemical resistance, and thus are suitably used in applications such as concrete, resin reinforcement, and ropes.
However, since the para-type wholly aromatic copolyamide fiber is spun from an isotropic dope, it has been required to be stretched at a high magnification in order to obtain high mechanical properties as compared with the paraphenylene terephthalamide fiber. However, para-type wholly aromatic copolyamides have a very rigid molecular structure, which makes it difficult to perform uniform and stable stretching. As a result, there is a problem that the tensile modulus is slightly inferior. It was.

Accordingly, various studies have been made to improve the tensile elastic modulus of para-type wholly aromatic copolyamide fibers. For example, in Patent Documents 1 to 3, for spun and stretched para-type wholly aromatic copolyamide fibers, A method of performing tension heat treatment has been proposed.
However, in these methods, since the tension heat treatment with a high tension of 20 to 90% of the tensile breaking tension is performed, a part of the single yarn constituting the fiber bundle is easily broken, and the tension heat treatment is continuously performed. When performing the above, there are cases where winding around a roller or the like frequently occurs.

  In particular, when the number of filaments constituting the fiber is large, heat is not uniformly applied to each single yarn constituting the fiber during the tension heat treatment, and as a result, part of the single yarn constituting the fiber bundle. In addition, breakage was more likely to occur. When a break occurs in a part of a single yarn constituting a fiber, the number of single yarns effective for expressing mechanical properties is reduced, so that not only the tensile strength of the fiber bundle but also the tensile elastic modulus is improved so much. It becomes difficult to do.

JP-A-7-166417 JP-A-8-296116 JP-A-8-311715

  An object of the present invention is to provide a method for producing a para-type wholly aromatic copolyamide fiber having a high tensile elastic modulus and having excellent processability.

  The present inventor has intensively studied to solve the above problems. As a result, after opening the para-type wholly aromatic copolyamide raw material fiber, it was found that the above-mentioned problems can be solved by tension heat treatment at a specific range of tension and temperature, and the present invention has been completed.

  That is, the present invention includes a fiber-opening process for opening a para type wholly aromatic copolyamide raw material fiber, and a tension heat treatment in which heat treatment is performed at a temperature of 50 ° C. to 450 ° C. under a tension of 2.0 to 6.0 cN / dtex. And a process for producing a para type wholly aromatic copolyamide fiber.

  The para-type wholly aromatic copolyamide fiber obtained by the production method of the present invention is a fiber excellent in tensile modulus while having the heat resistance inherent in the para-type wholly aromatic copolyamide fiber. Further, according to the production method of the present invention, it is possible to obtain a fiber having excellent process stability and high tensile strength that can suppress breakage of the single yarn constituting the fiber.

Hereinafter, embodiments of the present invention will be described in detail.
<Para-type wholly aromatic copolyamide>
The para-type wholly aromatic copolyamide in the present invention is a polymer in which one or more divalent aromatic groups are directly linked by an amide bond. Aromatic groups include those in which two aromatic rings are bonded via an oxygen, sulfur or alkylene group, or those in which two or more aromatic rings are directly bonded. Furthermore, these divalent aromatic groups may contain a lower alkyl group such as a methyl group or an ethyl group, a halogen group such as a methoxy group, a chloro group, or the like. Note that the position of the amide bond directly linking the divalent aromatic group is a para type.

<Method for producing para-type wholly aromatic copolyamide>
The para-type wholly aromatic copolyamide according to the present invention can be produced according to a conventionally known method. For example, a polymer solution of an aromatic polyamide can be obtained by reacting an aromatic dicarboxylic acid chloride component and an aromatic diamine component in an amide polar solvent.

[Raw material of para-type wholly aromatic copolyamide]
(Aromatic dicarboxylic acid dichloride component)
The aromatic dicarboxylic acid chloride component used as a raw material for the para-type wholly aromatic copolyamide raw fiber used in the present invention is not particularly limited, and generally known ones can be used. Examples thereof include terephthalic acid chloride, 2-chloroterephthalic acid chloride, 2,5-dichloroterephthalic acid chloride, 2,6-dichloroterephthalic acid chloride, 2,6-naphthalenedicarboxylic acid chloride and the like. Of these, terephthalic acid dichloride is preferred from the viewpoints of versatility and mechanical properties of the resulting fiber.

  These aromatic dicarboxylic acid dichlorides can be used not only in one type but also in two or more types, and the composition ratio is not particularly limited. In the present invention, a small amount of a component such as isophthalic acid dichloride that forms a bond other than the para position may be contained.

(Aromatic diamine component)
The aromatic diamine component used as a raw material for the para-type wholly aromatic copolyamide raw fiber used in the present invention is not particularly limited, and generally known ones can be used. For example, p-phenylenediamine, 2-chloro-p-phenylenediamine, 2,5-dichloro-p-phenylenediamine, 2,6-dichloro-p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4 ' -Diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone and the like can be mentioned.

These aromatic diamine components can use not only one type but also two or more types, and the composition ratio is not particularly limited. In addition, in this invention, components, such as metaphenylenediamine which forms a bond other than para position, may be contained in a small amount.
Among these, from the viewpoint of mechanical strength of the resulting fiber, it is preferable to use p-phenylenediamine and 3,4'-diaminodiphenyl ether alone or in combination, and p-phenylenediamine and 3,4 Most preferably, it is used in combination with '-diaminodiphenyl ether.

  When paraphenylenediamine and 3,4'-diaminodiphenyl ether are used in combination, the composition ratio is not particularly limited, but is 30 to 70 mol% and 70, respectively, based on the total aromatic diamine amount. It is preferable to set it as -30 mol%, More preferably, it is 40-60 mol%, 60-40 mol%, respectively, Most preferably, it is respectively 45-55 mol%, 55-45 mol%.

(Combination of aromatic dicarboxylic acid dichloride component and aromatic diamine component)
Accordingly, examples of the para type wholly aromatic copolyamide used in the present invention include copolyparaphenylene 3,4′-oxydiphenylene terephthalamide, polyparaphenylene terephthalamide, and the like.

[Raw material composition ratio]
The ratio of the aromatic dicarboxylic acid chloride component to the aromatic diamine component is preferably in the range of 0.90 to 1.10 as the molar ratio of the aromatic dicarboxylic acid chloride component to the aromatic diamine component. More preferably, it is in the range of 95 to 1.05. When the molar ratio of the aromatic dicarboxylic acid chloride component is less than 0.90 or exceeds 1.10, the reaction with the aromatic diamine component does not proceed sufficiently and a high degree of polymerization cannot be obtained, which is not preferable.

[Reaction conditions]
The reaction conditions for the aromatic dicarboxylic acid chloride component and the aromatic diamine component are not particularly limited. The reaction between acid chloride and diamine is generally rapid, and the reaction temperature is preferably, for example, in the range of -25 ° C to 100 ° C, more preferably in the range of -10 ° C to 80 ° C.

[Polymerization solvent]
Examples of the solvent used for the polymerization of the para type wholly aromatic copolyamide include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone (hereinafter sometimes referred to as NMP), N -Organic polar amide solvents such as methyl caprolactam, water-soluble ether compounds such as tetrahydrofuran and dioxane, water-soluble alcohol compounds such as methanol, ethanol and ethylene glycol, water-soluble ketone compounds such as acetone and methyl ethyl ketone, acetonitrile and propio Examples thereof include water-soluble nitrile compounds such as nitrile. These solvents can be used singly or as a mixed solvent of two or more. Note that the solvent used is preferably dehydrated.
In the production of the para-type wholly aromatic copolyamide used in the present invention, N-methyl-2-pyrrolidone (NMP) is used from the viewpoints of versatility, harmfulness, handleability, solubility in para-type wholly aromatic copolyamide, and the like. ) Is most preferred.

[Other polymerization conditions]
In order to increase the solubility of the resulting para-type wholly aromatic copolyamide, an appropriate amount of a generally known inorganic salt may be added before, during or after the polymerization. Examples of such inorganic salts include lithium chloride and calcium chloride.
Moreover, the terminal of para type wholly aromatic copolyamide can also be sealed. When the terminal is sealed with a terminal blocking agent, for example, phthalic acid chloride and its substituted product, aniline and its substituted product, and the like can be used as the terminal blocking agent.
In addition, aliphatic or aromatic amines, quaternary ammonium salts, and the like can be used in combination in order to capture an acid such as hydrogen chloride.
After completion of the reaction, a basic inorganic compound such as sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide or the like may be added as necessary to carry out a neutralization reaction.

[Post-polymerization, etc.]
The para-type wholly aromatic copolyamide obtained as described above can be put into a non-solvent such as alcohol or water, precipitated, and taken out as a pulp. The para-type wholly aromatic copolyamide taken out can be dissolved again in another solvent and then used for fiber molding, but the polymer solution obtained by the polymerization reaction is directly adjusted to a spinning solution (dope). It is also possible to use it. The solvent used for taking out once and dissolving it again is not particularly limited as long as it dissolves the para-type wholly aromatic copolyamide, but it is used for polymerization of the para-type wholly aromatic copolyamide. It is preferable to use a solvent.

<Method for producing para-type wholly aromatic copolyamide raw material fiber>
In the method for producing a para type wholly aromatic copolyamide raw fiber used in the present invention, a wet spinning method or a semi-dry semi-wet spinning method is employed. That is, first, a spinning solution (polymer dope) containing para-type wholly aromatic copolyamide and a solvent is discharged from a spinneret to form a coagulated yarn. Then, after removing the solvent contained in the coagulated yarn, the final para-type wholly aromatic copolyamide raw material fiber is obtained by performing heat drawing or the like.

  Below, an example of the manufacturing method of the para type wholly aromatic copolyamide raw material fiber used for this invention is demonstrated.

[Process for adjusting spinning solution (polymer dope)]
In obtaining the para type wholly aromatic copolyamide fiber, first, in the spinning solution (polymer dope) adjustment step, a spinning solution (polymer dope) containing the para type wholly aromatic copolyamide and a solvent is prepared.
The method for preparing the spinning solution (dope) containing the para-type wholly aromatic copolyamide and the solvent is not particularly limited. In addition, as the solvent used for the preparation of the spinning solution (dope), it is preferable to use the solvent used for the polymerization of the para-type wholly aromatic copolyamide described above. In addition, the solvent used may be one type alone or a mixed solvent obtained by mixing two or more types of solvents. The polymer can be used as it is without being isolated from the polymer solution obtained by the production of the para-type wholly aromatic copolyamide.

Moreover, you may mix | blend other arbitrary components, such as an additive, in the range which does not exceed the summary of this invention in order to provide functionality etc. to a fiber. When an additive or the like is blended, it can be introduced in adjusting the spinning solution (dope). The method of introduction is not particularly limited, and for example, it can be introduced into the dope using a ruder or a mixer.
The polymer concentration in the spinning solution (dope), that is, the concentration of the para-type wholly aromatic copolyamide is preferably in the range of 0.5 to 30% by mass, and in the range of 1 to 20% by mass. Further preferred. When the polymer concentration in the spinning solution (dope) is less than 0.5% by mass, the entanglement of the polymer is small, so that the viscosity necessary for spinning cannot be obtained, and the ejection stability during spinning decreases. . On the other hand, when the polymer concentration exceeds 30% by mass, the viscosity of the dope increases abruptly, so that the discharge stability at the time of spinning decreases, and stable spinning is performed by the rapid pressure increase in the spinning pack. It becomes difficult.

[Spinning and coagulation process]
In the spinning / coagulation step, the coagulated yarn is formed by a wet method, a semi-dry semi-wet method, or the like. For example, in the semi-dry semi-wet method, a spinning solution (dope) is discharged from a spinneret and solidified in a coagulation bath made of a poor solvent to obtain an undrawn yarn. The spinneret used here preferably has 133 holes or more. The temperature of the spinning solution (dope) when passing through the spinneret and the temperature of the spinneret are not particularly limited, but from the viewpoint of spinnability and discharge pressure of the spinning solution (dope), 80 It is preferable to set it to -120 degreeC.

Next, the spinning solution (dope) discharged from the spinneret is coagulated in a coagulating liquid. At this time, when the temperatures of the spinneret and the coagulating liquid are greatly different, when the spinneret and the coagulating liquid come into contact with each other, the respective temperatures change, and as a result, it becomes difficult to control the spinning process. Therefore, when the temperatures of the spinneret and the coagulating liquid are greatly different, it is preferable to perform semi-dry semi-wet spinning provided with an air gap. The length of the air gap is not particularly limited, but is preferably in the range of 5 to 25 mm from the viewpoints of temperature controllability, spinnability, and the like.
The coagulation liquid used here is, for example, an N-methyl-2-pyrrolidone (NMP) aqueous solution, and its temperature and concentration are not particularly limited. As long as there is no problem in the solidified state of the formed yarn and the subsequent process passability, it can be adjusted as appropriate.

[Washing process]
Next, the coagulated yarn obtained above is washed with water. The water washing step aims to remove a solvent from the yarn by diffusing a solvent such as N-methyl-2-pyrrolidone (NMP) contained in the yarn using water. In addition, when the amount of residual solvent in the yarn after passing through the water washing step is high, it may be unfavorable because the step passability in the subsequent step, the physical properties and quality of the obtained fiber are deteriorated.
In the water washing step, the fiber bundle constantly passes, which causes a problem that the solvent concentration of the water washing bath becomes high. For this reason, it is preferable to constantly supply water containing no solvent and keep the solvent concentration in the washing bath constant.

[Particle application process]
For the yarn after washing with water, it is preferable to provide inorganic fine particles for the purpose of suppressing the fusion of single fibers in the subsequent drying step, heat drawing step and the like. The kind and adhesion amount of the inorganic fine particles to be imparted are not particularly limited as long as fusion between single fibers can be suppressed. In addition, the inorganic fine particles attached here can be removed by spraying a water shower or compressed air in the removing step after the hot stretching step.

[Drying process]
Next, in the drying step, the fiber from which the solvent has been removed is dried. The drying conditions are not particularly limited, and there is no problem as long as moisture attached to the fibers can be sufficiently removed. However, in consideration of workability and deterioration of the fibers due to heat, the temperature is in the range of 150 to 250 ° C. It is preferable. For drying, either a contact type drying apparatus such as a roller or a non-contact type drying apparatus such as passing a fiber through a drying furnace can be used.

[Hot drawing process]
Next, the dried fiber is hot-drawn. The purpose of this step is to highly orient the polymer molecules in the fiber and impart strength by hot drawing of the fiber. The heat stretching temperature at this time is preferably in the range of 300 to 600 ° C, more preferably 320 ° C to 580 ° C, and most preferably 350 to 550 ° C. When the heat drawing temperature is less than 300 ° C., the yarn cannot be sufficiently drawn, which is not preferable. On the other hand, when the temperature exceeds 600 ° C., the polymer is thermally decomposed, so that the fiber is deteriorated and it is difficult to obtain a high-strength yarn.
The draw ratio in the hot drawing step is preferably 5 to 15 times, but is not particularly limited to this range. Further, this hot stretching process may be performed in multiple stages as required, and there is no problem.

[Particle removal]
Next, when inorganic fine particles are provided in advance for the purpose of suppressing fusion between single fibers, it is preferable to remove them. The removal of the inorganic fine particles can be omitted if necessary, but the inorganic fine particles affect the hue of the fiber and cause scum, so if it is excessively attached, remove it. It is preferable.
The removal method is not particularly limited, but excess inorganic fine particles can be removed by spraying water shower or compressed air.

[Take-up]
Then, if necessary, an oil agent is applied for the purpose of imparting charge suppression or lubricity to the fiber, and finally wound with a winder. The kind of oil agent to be applied, the amount to be applied, and the like are not particularly limited, and a known method can be applied as it is. Also, the winding method with a winder is not particularly limited, and the winding can be performed by appropriately adjusting the winding conditions using a known winder.

[Physical properties of para-type wholly aromatic copolyamide raw fiber]
The para-type wholly aromatic copolyamide raw material fiber used in the present invention has a tensile modulus of 510 cN / dtex or more, a tensile strength of 23.3 cN / dtex or more, and a single yarn number of 133 or more. preferable. When the tensile elastic modulus is less than 510 cN / dtex, the raw fiber cannot be sufficiently crystallized, so that the elastic modulus cannot be increased sufficiently in the subsequent tension heat treatment step. In addition, when the tensile strength is less than 23.3 cN / dtex, the raw fiber is not sufficiently crystallized and includes many defects in the raw fiber. Is likely to occur, and process passability deteriorates. Furthermore, when the number of single yarns of the raw material fibers is less than 133, the effect of the opening process in the tension heat treatment process is reduced, but the cost is increased.

<Manufacture of para-type wholly aromatic copolyamide fiber>
The method for producing a para-type wholly aromatic copolyamide fiber of the present invention uses the above-described para-type wholly aromatic copolyamide fiber as a material, and performs the following opening process and tension heat treatment process. In the present invention, it is only necessary to include a fiber opening step and a tension heat treatment step, and other steps may be present if necessary.

[Opening process]
In the fiber opening process, an operation of widening the para-type wholly aromatic copolyamide fiber bundle as a raw material is performed. The width of the para-type wholly aromatic copolyamide fiber bundle after the opening process is preferably 12 mm or more. More preferably, the range is 20 to 60 mm.
When the width of the fiber bundle is less than 12 mm, it is difficult to uniformly apply heat to each single yarn, resulting in non-uniform stretching, and breakage of single yarn is likely to occur. On the other hand, when the width of the fiber bundle exceeds 60 mm, winding around a roller or the like is likely to occur during tension heat treatment, and process passability is deteriorated.
The opening method is not particularly limited, and examples thereof include a method of bringing a fiber bundle into contact with a curved surface, a method of bringing an air flow into contact with a fiber bundle, and the like.

[Tension heat treatment process]
In the tension heat treatment step, heat treatment in a specific temperature range is performed while applying a high tension in a specific range. In addition, it is common to implement the tension heat treatment process as a process after the above-described opening process, and if it is after performing the opening process, it may be immediately after or any other arbitrary value in between. There may be a process.
In the tension heat treatment step, it is necessary to set the tension and temperature within specific ranges, but other conditions such as processing speed and processing length are not particularly limited, and are set as appropriate. can do.

(tension)
It is essential that the tension in the tension heat treatment step is in the range of 2.0 to 6.0 cN / dtex. More preferably, it is the range of 2.5-5.0 cN / dtex. When the tension is less than 2.0 cN / dtex, it is difficult to improve the orientation of the molecular chain. On the other hand, when the tension exceeds 6.0 cN / dtex, the single yarn breakage occurs during the tension heat treatment. In addition, the tensile strength decreases and the winding around the roller is likely to occur due to single yarn breakage, and the processability of the tension heat treatment process is inferior.

(temperature)
The temperature in the tension heat treatment step is essential to be in the range of 50 to 450 ° C. More preferably, it is the range of 150-400 degreeC. When the temperature is lower than 50 ° C., the molecular chain of the para-type wholly aromatic copolyamide hardly moves and only elastic deformation occurs. As a result, the orientation of the molecular chain is hardly improved, and the tensile modulus is sufficiently increased. It cannot be improved. On the other hand, when the temperature exceeds 400 ° C., the polymer is thermally decomposed, so that the fiber is deteriorated and the tensile elastic modulus is lowered.

(Facility)
The equipment for performing the tension heat treatment is not particularly limited, but it is preferable that the para-type wholly aromatic copolyamide fiber is not broken by the friction during the tension heat treatment and is not fluffy. For example, a tension heat treatment facility provided with a non-contact type heating furnace between the delivery roller and the take-up roller, and a tension heat treatment facility provided with a heated delivery roller and a take-up roller can be mentioned.

[Physical properties of para-type wholly aromatic copolyamide fiber]
The para type wholly aromatic copolyamide fiber obtained by the production method of the present invention has a tensile modulus of 650 cN / dtex or more and a tensile strength of 23.2 cN / dtex or more.
In addition, since the production method of the present invention can exhibit a sufficient effect even when the number of single yarns constituting the para-type wholly aromatic polyamide fiber is large, the number of single yarns is preferably 133 filaments or more. .

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, this invention is not limited to this unless it exceeds the summary.

<Measurement and evaluation method>
In Examples and Comparative Examples, the following items were measured and evaluated by the following methods.

(1) Fineness of para-type wholly aromatic copolyamide raw material fiber and para-type wholly aromatic copolyamide fiber The obtained fiber bundle was wound up by 100 m using a known measuring instrument, and its mass was measured. A value obtained by multiplying the obtained mass by 100 was calculated as a mass per 10,000 m, that is, a fineness (dtex).

(2) Tensile strength, elongation at break, tensile elastic modulus of para-type wholly aromatic copolyamide raw fiber and para-type wholly aromatic copolyamide fiber Tensile tester (manufactured by INSTRON, trade name: INSTRON, model: 5565 type) Thus, measurement was performed under the following conditions using a yarn test chuck.
[Measurement condition]
Temperature: Room temperature Test piece: 75cm
Twist factor: 1
Test speed: 250 mm / min Chuck distance: 500 mm

(3) Tension in the tension heat treatment step Using a tension meter (manufactured by SCHMIDT, trade name: MECHANICAL TENSION METER, model: DN1), the tension between the feed roller and the take-up roller for performing the tension heat treatment is measured. (1) The value was calculated by dividing by the fineness of the para-type wholly aromatic copolyamide fiber measured in (1).

(4) Process passability Tensile heat treatment was performed for 10 minutes, and the process passability was evaluated according to the following evaluation criteria.
○: Fiber winding around the winding roller does not occur. ×: Fiber winding around the winding roller occurs.

<Example 1>
[Production of para-type wholly aromatic copolyamide]
Polycondensation by adding 100 parts by mass of terephthalic acid dichloride to 27 parts by mass of paraphenylenediamine and 50 parts by mass of 3,4'-diaminodiphenyl ether dissolved in N-methyl-2-pyrrolidone (NMP) by a known method. The reaction was carried out to obtain a copolyparaphenylene / 3,4′-oxydiphenylene / terephthalamide solution (spinning solution: polymer dope). The polymer concentration at this time was 6% by mass.

[Manufacture of para-type wholly aromatic copolyamide raw fiber]
(Spinning and coagulation process)
The spinning solution (polymer dope) obtained above is heated to 105 ° C., sent to a spinning pack heated to 105 ° C. with a spinneret having a hole diameter of 0.3 mm and a hole number of 1000, and 10 mm air A coagulation bath filled with a 50 ° C. aqueous solution having an NMP concentration of 30% by mass was passed through the gap to obtain a coagulated yarn bundle in which the polymer coagulated.

(Washing process / particulate application process)
Next, after the coagulated yarn bundle is passed through a water washing bath adjusted to 55 ° C. and washed with water, talc and osmos are added to the fiber weight for the purpose of suppressing the fusion of single yarns in the drying step and the heat drawing step. It was made to adhere 2 mass% with respect to.

(Drying process / heat stretching process)
Subsequently, the fiber to which talc and osmos were adhered was dried with a drying roller at 200 ° C., and then the first stage of thermal stretching was performed at 380 ° C. The draw ratio at this time was 2.4 times. Subsequently, second-stage heat drawing was performed at 530 ° C., and finally, a para-type wholly aromatic copolyamide raw material fiber was obtained. The draw ratio in the second stage was 4 times.
The obtained para-type wholly aromatic copolyamide raw material has the following properties: fineness of 1679 dtex, number of single yarns of 1000 filaments, tensile strength of 25.3 cN / dtex, elongation of 4.3%, and tensile modulus of 585 cN / dtex. there were.

[Production of high modulus para-type wholly aromatic copolyamide fiber]
(Opening process)
With respect to the obtained para type wholly aromatic copolyamide raw material fiber, 3 MPa of compressed air is blown through a tube having an inner diameter of 5 mm, and sprayed perpendicularly to the fiber axis direction of the fiber bundle from a distance of 5 mm from the fiber bundle, thereby reducing the width of the fiber bundle. The fiber was opened from 2 mm to 20 mm.

(Tension heat treatment process)
The opened para-type wholly aromatic copolyamide fiber bundle was subjected to tension heat treatment using a non-contact heat treatment furnace equipped with a feed roller and a take-up roller. The atmospheric temperature of the non-contact heating furnace was 340 ° C., the feed roller speed was 10 m / min, and the winding roller speed was adjusted so that the tension in the tension heat treatment step was 2.7 cN / dtex. Table 1 shows the evaluation results of the physical properties and process passability of the finally obtained para-type wholly aromatic copolyamide fiber.

<Example 2>
Para-type wholly aromatic copolyamide fibers were produced in the same manner as in Example 1, except that in the opening process, compressed air was blown from a distance of 10 mm from the fiber bundle, and the width of the fiber bundle was opened from 2 mm to 30 mm. Table 1 shows the evaluation results of physical properties and process passability of the obtained para-type wholly aromatic copolyamide fiber.

<Example 3>
Para-type wholly aromatic copolyamide fibers were produced in the same manner as in Example 1 except that in the opening process, compressed air was blown from a distance of 3 mm from the fiber bundle, and the width of the fiber bundle was opened from 2 mm to 40 mm. Table 1 shows the evaluation results of physical properties and process passability of the obtained para-type wholly aromatic copolyamide fiber.

<Example 4>
In the tension heat treatment step, the para-type total fragrance was the same as in Example 1, except that the ambient temperature of the non-contact heating furnace was 400 ° C. and the speed of the winding roller was adjusted so that the tension was 2.5 cN / dtex. Group copolyamide fibers were produced. Table 1 shows the evaluation results of physical properties and process passability of the obtained para-type wholly aromatic copolyamide fiber.

<Example 5>
Para-type wholly aromatic copolyamide fibers were produced in the same manner as in Example 1 except that in the tension heat treatment step, the speed of the winding roller was adjusted so that the tension was 4.3 cN / dtex. Table 1 shows the evaluation results of physical properties and process passability of the obtained para-type wholly aromatic copolyamide fiber.

<Comparative Example 1>
Para-type wholly aromatic copolyamide fibers were produced in the same manner as in Example 1 except that fiber opening was not performed in the fiber opening step and the width of the fiber bundle was 3 mm. Table 1 shows the evaluation results of physical properties and process passability of the obtained para-type wholly aromatic copolyamide drawn fiber.

  The para-type wholly aromatic copolyamide fiber obtained by the production method of the present invention is a fiber excellent in tensile elastic modulus while having performances such as heat resistance inherent in the para-type wholly aromatic copolyamide fiber. At the same time, since the breakage of the single yarn constituting the fiber is suppressed, the fiber has high tensile strength. Therefore, it is useful for applications such as reinforcing materials such as concrete and resin, ropes and the like. In addition, according to the production method of the present invention, there is no restriction on the number of filaments constituting the fiber, and as a result, there is no restriction on the total fineness of the fiber, so that the resulting fiber can be applied to a wider range of industrial materials. It becomes.

Claims (4)

Opening process of opening para-type wholly aromatic copolyamide raw fiber,
A tension heat treatment step of heat treatment at a temperature of 50 to 450 ° C. under a tension of 2.0 to 6.0 cN / dtex, and a method for producing a para-type wholly aromatic copolyamide fiber.   The method for producing a para-type wholly aromatic copolyamide fiber according to claim 1, wherein in the opening step, the width of the para-type wholly aromatic copolyamide raw material fiber is opened to 12 mm or more.   The method for producing a para-type wholly aromatic copolyamide fiber according to claim 1 or 2, wherein the wholly aromatic copolyamide fiber is a copolyparaphenylene 3,4'-oxydiphenylene terephthalamide fiber. A para-type wholly aromatic copolyamide fiber obtained by the production method according to claim 1,
Para-type wholly aromatic copolyamide fiber having a tensile modulus of 650 cN / dtex or more and a tensile strength of 23.2 cN / dtex or more.