JP6321425B2 - Totally aromatic polyamide fiber - Google Patents

Description

  The present invention relates to wholly aromatic polyamide fibers. More specifically, the present invention relates to a wholly aromatic polyamide fiber having improved light resistance without reducing the tensile strength of the fiber.

  Conventionally, it is known that wholly aromatic polyamides produced from aromatic diamines and aromatic dicarboxylic acid dihalides are excellent in heat resistance and flame retardancy. The wholly aromatic polyamide fibers are used in fields where these characteristics are required, for example, industrial uses such as filters and electronic parts, disaster prevention safety clothing uses such as protective clothing, and the like.

  However, the wholly aromatic polyamide fiber is not sufficiently stable to light, and undergoes significant discoloration or coloring when irradiated with light, and also deteriorates physical properties such as mechanical properties due to a decrease in molecular weight. The deterioration with respect to light is remarkable as compared with a general organic polymer material. For example, when it is directly exposed to sunlight, the deterioration is caused in a short time. Therefore, when used for protective clothing, interiors, vehicle interior materials, fish nets, ropes, etc. that are directly or indirectly exposed to light, there have been significant restrictions.

  From this point of view, attempts to improve the light resistance of aromatic polyamides have been proposed. For example, Patent Document 1 proposes a method for improving light resistance by adding a benzotriazole-based ultraviolet absorber and an antioxidant (see Patent Document 1). However, the degree of improvement in light resistance by this method is still not satisfactory.

  Also disclosed is a method of improving the light resistance of an aromatic polyamide by adding a piperidine derivative (see Patent Document 2). However, aromatic polyamides produced by this method have problems such as volatilization of the added UV absorber during molding, decomposition by heat, and bleed out gradually during use, improving long-term light resistance. The effect was not obtained.

  Furthermore, a method for improving light resistance by incorporating carbon black into an aromatic polyamide has been disclosed (see Patent Documents 3 to 5). However, as the amount of carbon black added increases, the mechanical properties such as tensile strength and elastic modulus of the fiber decrease, making it difficult to achieve both improved light resistance and sustained mechanical properties.

Japanese Patent Laid-Open No. 49-10032 Japanese Patent Laid-Open No. 50-34344 JP 2007-23451 A JP-A 64-85316 Japanese Patent Laid-Open No. 6-81111

  The present invention has been made against the background of the prior art as described above, and an object thereof is to provide a wholly aromatic polyamide fiber having both mechanical strength and light resistance.

  The present inventor has intensively studied to solve the above problems. As a result, a structural repeating unit (I) represented by the following chemical formula (I), a structural repeating unit (II) represented by the following chemical formula (II), and a structural repeating unit represented by the following chemical formula (III) ( It has been found that a fiber made of wholly aromatic polyamide containing III) in a specific ratio has high light resistance and mechanical strength, and has completed the present invention.

  That is, the present invention relates to a structural repeating unit (I) represented by the chemical formula (I), a structural repeating unit (II) represented by the chemical formula (II), and a structural repeating unit (III) represented by the chemical formula (III). A wholly aromatic polyamide fiber comprising a wholly aromatic polyamide, wherein the structural repeating unit (II) is a sum of the structural repeating unit (I), the structural repeating unit (II), and the structural repeating unit (III). 40 to 60 mol%, and the structural repeating unit (III) is 5 to 10 mol% based on the total of the structural repeating unit (I), the structural repeating unit (II), and the structural repeating unit (III). Is a wholly aromatic polyamide fiber.

  The wholly aromatic polyamide fiber of the present invention has excellent mechanical strength and, for example, does not cause a decrease in strength even in an environment where it is exposed to sunlight for a long period of time, and has excellent light resistance. For this reason, it can be used suitably for a fish net etc., for example.

Hereinafter, embodiments of the present invention will be described in detail.
<Para-type wholly aromatic polyamide>
[Structure of para-type wholly aromatic polyamide]
The para-type wholly aromatic polyamide constituting the fiber of the present invention includes a structural repeating unit (I) represented by the following chemical formula (I), a structural repeating unit (II) represented by the following chemical formula (II), and It is a wholly aromatic polyamide containing a structural repeating unit (III) represented by the following chemical formula (III) in a specific ratio.

[Structural repeat unit ratio]
In the para type wholly aromatic polyamide constituting the fiber of the present invention, the ratio of the structural repeating unit (II) is the sum of the structural repeating unit (I), the structural repeating unit (II), and the structural repeating unit (III). It is 40-60 mol% with respect to it, Preferably it is 45-55 mol%. When the ratio of the structural repeating unit (II) is less than 40 mol%, the intrinsic viscosity of the polymer becomes high and fiberization becomes difficult. On the other hand, when the ratio of the structural repeating unit (II) exceeds 60 mol%, the strength of the fiber is significantly reduced, which is not preferable.

  At the same time, the ratio of the structural repeating unit (III) is 5 to 10 mol%, preferably 5 to 5%, based on the total of the structural repeating unit (I), the structural repeating unit (II), and the structural repeating unit (III). 8 mol%. When the ratio of the structural repeating unit (III) is less than 5 mol%, sufficient light resistance cannot be obtained. On the other hand, when the ratio of the structural repeating unit (III) exceeds 10 mol%, it is not preferable because the strength of the fiber is significantly reduced.

<Method for producing para-type wholly aromatic copolyamide>
The wholly aromatic polyamide used in the present invention can be produced according to a conventionally known method. For example, it can be obtained by subjecting a dicarboxylic acid dichloride component and an aromatic diamine component to low-temperature solution polymerization or interfacial polymerization in an amide polar solvent.

[Para-type wholly aromatic polyamide raw material]
(Aromatic diamine component)
Examples of the aromatic diamine component used in the present invention include p-phenylenediamine, 2-chloro p-phenylenediamine, 2,5-dichloro p-phenylenediamine, 2,6-dichloro p-phenylenediamine, and m-phenylenediamine. 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl ether , 2-aminobenzamide and the like, but are not limited thereto.

  In the present invention, at least two types of aromatic diamine components and one type of anthranilamide derivative are combined in accordance with the ratio of the structural repeating unit (I), the structural repeating unit (II), and the structural repeating unit (III). It is important to use them. The aromatic diamine component and anthranilamide derivative constituting the structural repeating unit (I), the structural repeating unit (II), and the structural repeating unit (III) can be used alone or in combination of two or more. .

An anthranilamide derivative monomer used in the present invention is represented by the following chemical formula.

  (In the formula, R1 and R2 are a hydrogen atom, a halogen atom, an amino group, a nitro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 2 to 8 carbon atoms, an acyl group having 2 to 8 carbon atoms, and a carbon number. 2-8 acyloxy groups, C2-C8 alkoxycarbonyl groups, C2-C8 acylamino groups.)

  In the present invention, it is preferable to use p-phenylene diamine, m-phenylene diamine, or 3,4'-diaminodiphenyl ether as the aromatic diamine. As the anthranilamide derivative, R1 and R2 in the above formula are hydrogen atoms. Is preferably used.

(Aromatic dicarboxylic acid dichloride component)
Examples of the aromatic dicarboxylic acid dichloride component used in the present invention include isophthalic acid chloride, terephthalic acid chloride, 2-chloroterephthalic acid chloride, 2,5-dichloroterephthalic acid chloride, and 2,6-dichloroterephthalic acid. Examples include, but are not limited to, chloride and 2,6-naphthalenedicarboxylic acid chloride. 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.

Of these, terephthalic acid dichloride and isophthalic acid dichloride are preferably used.
Accordingly, examples of the wholly aromatic polyamide in the present invention include copolyparaphenylene 3,4'-oxydiphenylene terephthalamide, polyparaphenylene terephthalamide, and polymetaphenylene terephthalamide.

[Polymerization of para-type wholly aromatic copolyamide]
(Polymerization solvent)
Examples of the solvent for polymerizing a wholly aromatic polyamide include organic polar amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and N-methylcaprolactam, tetrahydrofuran And water-soluble ether compounds such as dioxane, water-soluble alcohol compounds such as methanol, ethanol and ethylene glycol, water-soluble ketone compounds such as acetone and methyl ethyl ketone, and water-soluble nitrile compounds such as acetonitrile and propionitrile. These solvents can be used alone or as a mixed solvent of two or more. The solvent is preferably dehydrated.

[Inorganic salt]
In order to increase the solubility, an appropriate amount of a known inorganic salt may be added before, during or after the polymerization. Examples of such inorganic salts include lithium chloride and calcium chloride.

[Raw material composition ratio]
The ratio of the aromatic diamine component to the aromatic dicarboxylic acid dichloride component is preferably 0.90 to 1.10, more preferably 0.95 to 1 as the molar ratio of the aromatic dicarboxylic acid dichloride component to the aromatic diamine component. .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.

[Other polymerization conditions]
The terminal of the wholly aromatic polyamide may be sealed. In the case of sealing with an end-capping agent, for example, phthalic acid chloride and its substituted product, aniline and its substituted product can be used.
In addition, an aliphatic or aromatic amine or a quaternary ammonium salt can be used in combination to capture an acid such as hydrogen chloride to be generated.
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 wholly aromatic polyamide obtained as described above can be put into a poor solvent such as alcohol and water, precipitated, and taken out in the form of pulp. The extracted para-type wholly aromatic polyamide can be dissolved again in another solvent and used for molding, but the solution obtained by the polymerization reaction can be used as it is as a molding solution. The solvent used for once taking out and then dissolving again is not particularly limited as long as it dissolves the wholly aromatic polyamide, but the solvent used for the polymerization of the wholly aromatic polyamide is preferable.

[Other additives]
In addition, in this invention, a filler can be used together in the range which does not impair a physical property. Examples of the filler used include non-fibrous fillers such as fibrous or plate-like, scale-like, granular, indeterminate, and crushed products. Specific examples include glass fibers, PAN-based and pitch-based carbon fibers. , Stainless steel fibers, metal fibers such as aluminum fibers and brass fibers, organic fibers other than wholly aromatic polyamide fibers, gypsum fibers, ceramic fibers, zirconia fibers, alumina fibers, silica fibers, titanium dioxide fibers, silicon carbide fibers, rock wool, Potassium titanate whisker, barium titanate whisker, aluminum borate whisker, silicon nitride whisker, mica, layered clay mineral, talc, kaolin, silica, calcium carbonate, glass beads, glass flakes, glass microballoon, clay, molybdenum disulfide, straw Stenite, titanium dioxide, oxidation Lead, calcium polyphosphate, graphite, metal powders, metal flakes, metal ribbons, metal oxides, other than boron nitride particles of the present invention, carbon powder, graphite, carbon flake, such flake carbon. Moreover, said filler can also be used in combination of 2 or more types.

  In addition to the polymer used in the present invention and the resulting fiber, in addition to these, various additives such as antioxidants, ultraviolet absorbers, anti-degradation agents such as light stabilizers, lubricants, antistatic agents, and release agents. In addition, colorants such as plasticizers and pigments may be used in combination. The amount of the additive used can be appropriately selected according to the type of additive as long as the original physical properties of the resulting fiber are not impaired.

<Method for producing para-type wholly aromatic polyamide fiber>
In producing the para-type wholly aromatic polyamide fiber of the present invention, the wholly aromatic polyamide solution (which may be the polymer dope produced at the time of producing the wholly aromatic polyamide) is wet-spun or dry-spun, and then the solvent is used. Remove. Hereinafter, an example of the manufacturing method of the wholly aromatic polyamide fiber of this invention is shown.

[Preparation of spinning solution (polymer dope)]
In producing the fiber, an isotropic spinning solution (dope) in which para-type wholly aromatic polyamide is dissolved in an organic solvent is obtained. The method for adjusting the spinning solution (polymer dope) is not particularly limited. The organic solvent dope after solution polymerization may be used as it is, or the obtained wholly aromatic polyamide may be dissolved again in an organic solvent. Here, as the solvent used when the para-type wholly aromatic polyamide is dissolved again, the solvent used for the polymerization of the para-type wholly aromatic polyamide described above can be used.

[Spinning / Coagulation]
Using the isotropic dope (spinning solution) adjusted as described above, fibers are formed by a wet spinning method or a semi-dry semi-wet spinning method provided with an air gap. That is, first, the spinning solution (dope) obtained as described above is discharged from a nozzle and then brought into contact with a coagulating liquid in a coagulating bath through or without an air gap to form a coagulated yarn.

  As the coagulation bath, a poor solvent of wholly aromatic polyamide is used, but usually a good solvent is added to solidify so that the solvent of the wholly aromatic polyamide dope quickly escapes and the defect of the wholly aromatic polyamide fiber does not occur. Adjust the speed. In general, it is preferable to use water as the poor solvent and a solvent for the wholly aromatic polyamide dope as the good solvent. The weight ratio of good solvent / poor solvent is preferably in the range of 15/85 to 40/60, although it depends on the solubility and coagulability of the wholly aromatic polyamide.

[Other processes]
After pulling up the solidified yarn from the coagulation liquid, the final para-type wholly aromatic polyamide fiber can be obtained by a known method. For example, the solvent is removed from the undrawn yarn formed by carrying out the water washing step, the drawing is carried out as necessary, and the final fiber is oriented by drawing as necessary after passing through the drying step and the like. Can be obtained.

[Stretching process]
The fibers of the present invention are preferably stretch-oriented. The drawing method is not particularly limited, and may be any of not only washing drawing in a coagulated yarn state and boiling water drawing but also heating drawing in a dry yarn state. Moreover, there is no restriction | limiting in particular about a draw ratio, However, It is preferable that it is 5 times or more, and it is further more preferable that it is 8 times or more. By controlling the draw ratio, the elongation and strength of the resulting aromatic polyamide fiber can be controlled.

The fibers of the present invention are preferably highly oriented and crystallized with a degree of crystal orientation determined by wide-angle X-ray diffraction of 89% or more and a degree of crystallinity of 74% or more. When one or both of the crystal orientation degree and the crystallinity degree are low, the mechanical properties of the resulting fiber are likely to be insufficient.
In the case of carrying out hot stretching, the temperature is preferably 300 to 550 ° C., more preferably 350 to 500 ° C., although it depends on the polymer skeleton of the wholly aromatic polyamide, and the draw ratio is preferably 4 times. As described above, more preferably 4 to 10 times.

<Aromatic polyamide fiber>
(Single yarn fineness)
The single yarn fineness of the para-type wholly aromatic polyamide fiber of the present invention is preferably 0.5 to 50 dtex, more preferably 1.0 to 10 dtex. If it is less than 0.5 dtex, the spinning property may become unstable. Moreover, since the specific surface area of a fiber becomes large, it is easy to receive light resistance deterioration. On the other hand, if it exceeds 50 dtex, the specific surface area of the fiber becomes small, and it is difficult to undergo light resistance deterioration, but coagulation tends to be incomplete in the spinning process. The physical properties also tend to decrease.

(Use)
The para-type wholly aromatic polyamide fiber of the present invention can constitute fiber structures such as braids, ropes, twisted cords, yarns, and cotton in addition to fabrics such as woven fabrics, knitted fabrics, and nonwoven fabrics.

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

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

[Fineness]
It measured according to JIS-L-1015.

[Tensile strength of fiber]
Using a tensile tester (manufactured by INSTRON Co., Ltd., trade name: INSTRON, model: 5565 type), measurement was performed under the following conditions based on the procedure of ASTM D885.
(Measurement condition)
Temperature: Room temperature Measurement sample length: 500mm
Chuck tensile speed: 250 mm / min Initial load: 0.2 cN / dtex

[Strength retention (light resistance)]
In accordance with JIS L 0842-71, the tensile strength was measured before and after 180,000 kJ / m ² irradiation for 100 hours with an ultraviolet carbon arc lamp type weather resistance tester. Using the tensile strength values before and after the light irradiation, the strength retention was determined by the following formula.
Strength retention (%) = (Tensile strength after light irradiation) / (Tensile strength before light irradiation) × 100

<Example 1>
[Polymerization of para-type wholly aromatic polyamide]
108.0 g of paraphenylenediamine was dissolved in 1.0 L of dioxane, and 8.0 g of pyridine was added thereto. An additional 115.0 g of isatoic anhydride was added and reacted under reflux for 5 hours. After the reaction, 1.0 L of ethanol was added to the reaction solution and allowed to stand at 0 ° C. for 12 hours. The precipitated white crystals were collected by filtration and further recrystallized with ethanol. The precipitated crystals were collected by filtration and dried at 100 ° C. for 6 hours to obtain an anthranilamide derivative monomer.
12.7 g (5 mol%) of anthranilamide derivative monomer obtained in 2.139 L of N-methyl-2-pyrrolidone (NMP), 22.8 g (20 mol%) of paraphenylenediamine, and 3,4'-diaminodiphenyl ether 52.8 g (25 mol%) was weighed and added, and dissolved at room temperature. To the obtained diamine solution, 106.9 g (50 mol%) of terephthalic acid chloride was added and reacted to polymerize the polymer. Subsequently, 172.2 g of NMP dispersion containing 22.5% by mass of calcium hydroxide was added for neutralization to obtain a polymer solution.

[Preparation of spinning solution (polymer dope)]
The obtained polymer solution (inherent viscosity (IV) measured at 30 ° C. for a solution having a polymer concentration of 0.5 g / dl in 98% concentrated sulfuric acid at 3.3) is a NMP solution having a concentration of 6% by mass. To prepare a spinning solution (polymer dope).

[Spinning / Coagulation]
Using the obtained dope, it was discharged from a spinneret with 25 holes, spun into an aqueous solution having an NMP concentration of 30% by mass through an air gap of about 10 mm, and solidified (semi-dry semi-wet spinning method). It was washed with water, dried, and then drawn at a temperature of 530 ° C. by 10.0 times to obtain a para type wholly aromatic polyamide fiber. Table 1 shows the physical properties and the like of the obtained fiber.

<Example 2>
The para type wholly aromatic polyamide fiber was prepared in the same manner as in Example 1 except that 2.5 mol% of the anthranilamide derivative monomer, 22.5 mol% of paraphenylenediamine, and 25 mol% of 3,4'-diaminodiphenyl ether. Got. Table 1 shows the physical properties and the like of the obtained fiber.

<Comparative Example 1>
Para-type wholly aromatic polyamide fibers were obtained in the same manner as in Example 1 except that 25 mol% of paraphenylenediamine and 25 mol% of 3,4′-diaminodiphenyl ether were used. Table 1 shows the physical properties and the like of the obtained fiber.

<Comparative example 2>
Para-type wholly aromatic polyamide fibers were obtained in the same manner as in Example 1 except that 10 mol% of anthranilamide derivative monomer, 15 mol% of paraphenylenediamine, and 25 mol% of 3,4'-diaminodiphenyl ether were used. Table 1 shows the physical properties and the like of the obtained fiber.

<Comparative Example 3>
Para-type wholly aromatic polyamide fibers were obtained in the same manner as in Example 1 except that 1 mol% of the anthranilamide derivative monomer, 24 mol% of paraphenylenediamine, and 25 mol% of 3,4'-diaminodiphenyl ether. Table 1 shows the physical properties and the like of the obtained fiber.

<Comparative Example 4>
A polymer solution was obtained in the same manner as in Example 1 except that 25 mol% of paraphenylenediamine and 25 mol% of 3,4'-diaminodiphenyl ether were used. To the obtained polymer solution, NMP dispersion of carbon black (manufactured by Dainichi Seika Kogyo Co., Ltd., MPS-1100 Black (T)) was added so that the carbon black was 5% by mass with respect to the polymer. Then, using a planetary mixer (product name PVM-5) manufactured by Asada Tekko Co., Ltd., the mixture was heated and kneaded at 80 ° C. for 2 hours to obtain a carbon black-containing wholly aromatic polyamide solution.
Using the obtained carbon black-containing wholly aromatic polyamide solution as a spinning solution, a wholly aromatic polyamide fiber was obtained in the same manner as in Example 1. Table 1 shows the physical properties and the like of the obtained fiber.

Claims (1)

A wholly aromatic group comprising a structural repeating unit (I) represented by chemical formula (I), a structural repeating unit (II) represented by chemical formula (II), and a structural repeating unit (III) represented by chemical formula (III) A wholly aromatic polyamide fiber made of polyamide,
The structural repeating unit (II) is 40 to 60 mol% based on the total of the structural repeating unit (I), the structural repeating unit (II), and the structural repeating unit (III);
A wholly aromatic polyamide fiber in which the structural repeating unit (III) is 5 to 10 mol% based on the total of the structural repeating unit (I), the structural repeating unit (II), and the structural repeating unit (III).