WO2005026418A1 - Wholly aromatic polyamide fiber and process for producing the same - Google Patents

Abstract

A wholly aromatic polyamide fiber which has excellent mechanical properties (toughness factor) and can be produced while attaining satisfactory operation stability in the fiber formation step. The fiber comprises 100 parts by mass of a wholly aromatic polyamide and 0.05 to 20 parts by mass of particles of a lamellar clay mineral, e.g., hectorite, saponite, stivensite, beidellite, montmorillonite, or swelling mica.

Description

 Description Wholly aromatic polyamide fibers and method for producing the same

 The present invention relates to a wholly aromatic polyamide fiber containing a layered clay mineral and a method for producing the same. More specifically, the present invention relates to a wholly aromatic polyamide fiber containing a layered clay mineral and having improved mechanical properties, particularly toughness, and a method for producing the same. Background art

 In recent years, there has been a great deal of interest in providing high added value to polymers and enhancing their performance. In order to add high added value and high performance to polymers, the development of composite materials obtained by incorporating fillers into polymers is being actively pursued. Until now, fibrous or acicular fillers have been used as reinforcing fillers to improve the mechanical properties and heat resistance of polymers, thereby increasing the tensile strength, modulus, and bending of polymer materials. It is known that various properties such as strength, thermal dimensional stability, creep characteristics, warpage, abrasion resistance, surface hardness, heat resistance and impact resistance are improved.

However, the strength of the composite material is greatly affected by the interfacial adhesion between the filler and the polymer, in addition to the strength of the polymer used as the matrix of the composite material and the filler itself used as the filler. It is known that poor or poor polymer wettability with fillers affects not only the difficulty of manufacturing but also the strength of the product. For these reasons, fillers or polymers that exhibit high strength and high elasticity are used as materials. However, it is not always possible to obtain a composite material with excellent strength.

 In addition, it is generally known that filler-containing composite materials have a drawback of low elongation.

On the other hand, in the spinning process of wholly aromatic polyamide fibers (hereinafter sometimes referred to as “alamide fibers”), further improvement in process stability and quality (prevention of breakage of single yarn) is desired. Generally, the toughness factor (TF) is known as one of the parameters for evaluating industrial aramide fibers. The toughness factor (TF) is expressed as the product of the tensile strength (T '), measured in grams / denier, the square root of the elongation (E%), and (TF = T, XE ^1/2 ) . In the case of the fiber having a high toughness factor, the winding of the fiber around the drawing roll in the drawing process is reduced, and as a result, the single yarn breakage in the obtained yarn is reduced, and the stability of the drawing process is improved, and the obtained fiber is It is known that the quality of yarn is improved.

 As a method for improving the mechanical strength of a fiber, for example, it is known that the degree of orientation of the fiber is improved by drawing. However, when such a method is used, the elongation rate is improved along with the improvement in the tensile strength. It is known that it is difficult to manufacture a filament having a high toughness factor.

 Hitherto, in order to improve the mechanical properties and dimensional stability of polyamide fibers, it has been proposed to include a layered clay mineral as a filler (JP-A-3-81364, JP-A-4-1209822). Gazette, JP-A-8-3818). However, these are all directed to thermoplastic polyamides, and these patent documents disclose a layered clay mineral for a wholly aromatic polyamide fiber which is a non-thermoplastic polyamide. Utilization is not disclosed.

It also improves the mechanical properties and heat resistance of wholly aromatic polyamides. For this purpose, a method of using layered clay mineral as a filler has been studied. For example, Japanese Patent Application Laid-Open No. 11-236501 discloses an aqueous solution containing a diamine monomer and a solution of an acylated dicarboxylic acid monomer in a water-soluble organic solvent to carry out polycondensation of the monomer. In addition, a method for obtaining a wholly aromatic polyamide composite material useful as a high heat-resistant material by coexisting a clay mineral in an aqueous solution or an organic solvent solution has been disclosed in JP-A-11-255893. Japanese Patent Application Laid-Open No. H10-284,1992 discloses a method for efficiently obtaining a complex by solution-polymerizing a wholly aromatic polyamide in a solution of a layered clay mineral in a solvent capable of completely dissolving the same. No. 11-256034 discloses that a layered clay mineral is highly contained in a wholly aromatic polyamide by removing the organic solvent from a solution comprising a wholly aromatic polyamide, a layered clay mineral and an organic solvent. Fine Is dispersed, a method of obtaining a wholly aromatic poly Ami de complexes with improved mechanical properties have been proposed.

 However, in the prior art documents, by including the layered clay mineral as a filler, the mechanical properties of the wholly aromatic polyamide fiber are improved, and the layered clay mineral is included as a filler. As a result, a wholly aromatic polyamide fiber having a high toughness factor is not yet known. Disclosure of the invention

 An object of the present invention is to provide a wholly aromatic polyamide fiber having high mechanical properties, particularly a high toughness factor, and capable of spinning with good process stability in the spinning process, and industrially producing the same. The idea is to provide a way.

According to the study of the present inventors, a spinning solution containing a wholly aromatic polyamide and a layered clay mineral is wet-spun and drawn, and the drawing is performed. Oriented wholly aromatic polyamide fibers have been found to have excellent mechanical properties, especially toughness factors. Even more surprising is that rather than dispersing the individual layers of the layered clay mineral in the fibers quite evenly, it separates the layered clay mineral into the aromatic polyamide polymer matrix that composes the fibers. The present inventors have found that by scatteredly distributing a plurality of regions having relatively high distribution densities, it is possible to further increase the effect of improving the mechanical properties of fibers, particularly toughness factors, by the layered clay mineral particles. Was done.

 The stretch-orientated wholly aromatic polyamide fiber of the present invention is obtained by mixing a matrix composed of a wholly aromatic polyamide polymer with 0.05 to 20 parts by mass based on 100 parts by mass of the matrix. It is characterized by including a resin composition containing layered clay mineral particles dispersed and distributed in a trix.

 In the wholly aromatic polyamide fiber of the present invention, it is preferable that a plurality of regions in which the distribution density of the layered clay mineral particles is relatively high are scattered in the wholly aromatic polyamide matrix.

In the wholly aromatic polyamide fiber of the present invention, the wholly aromatic polyamide fiber is cut along the fiber axis, and the longitudinal section is observed with an electron microscope at a magnification of 100,000. When the total cross-sectional area S 1 of a plurality of regions in which the state of the fiber cross-section changes due to the influence of the layered clay mineral particles described above is measured with respect to the observed cross-sectional area S ² of μm ^2, the following equation (1) is obtained. The degree of dispersion Y of the layered clay mineral particles in the fiber, defined by:

 Y (%) = (S1 / S2) X100 (1) is preferably in the range of 0.1 to 40.

In the wholly aromatic polyamide fiber of the present invention, the layered clay mineral may be made of hectrite, savonite, stevensite, paiderite, or It preferably contains at least one member selected from the group consisting of ammonium sulphonate and swellable mica.

 In the wholly aromatic polyamide fiber of the present invention, it is preferable that the layered clay mineral particles have been subjected to a treatment with an inter-rate agent.

 In the wholly aromatic polyamide fiber of the present invention, the layered clay mineral particles preferably have an average layer thickness of 10 to 500 nm.

 In the wholly aromatic polyamide fiber of the present invention, the degree of orientation A of the layered clay mineral particles defined by the following formula (2):

 A (%) = [(180-w) Z180] X100 (2) (where, in the formula (2), in the X-ray analysis of the layered clay mineral particles, the reflection peak of the (001) plane of the layered clay mineral particles Represents the half-width of the intensity distribution measured along the Depay ring

Is preferably 50% or more.

 In the wholly aromatic polyamide fiber of the present invention, the tensile strength (T) of the wholly aromatic polyamide fiber is the same as that of the wholly aromatic polyamide fiber except that it does not contain the layered clay mineral particles. The ratio (T / To) to the tensile strength (To) of the comparative wholly aromatic polyamide fiber which is exactly the same as that of the fiber is preferably 1.1 or more.

 In the wholly aromatic polyamide fiber of the present invention, the elongation rate (Ε) of the wholly aromatic polyamide fiber is the same as that of the wholly aromatic polyamide fiber except that it does not contain the layered clay mineral particles. The ratio Ε / Εο to the elongation (Εο) of the comparative wholly aromatic polyamide fiber which is exactly the same as the amide fiber is preferably 1.1 or more.

 In the wholly aromatic polyamide fiber of the present invention, the toughness factor (TF) of the wholly aromatic polyamide defined by the following formula (3):

TF = Τ 'XE' ^1/2 (3) (In the above formula (3), T ′ represents a numerical value of the tensile strength in g / l.ldt ex unit of the wholly aromatic polyamide fiber, and E ′ is a unit of% of the wholly aromatic polyamide fiber. (Representing the numerical value of the elongation percentage) is preferably 30 or more.

 In the wholly aromatic polyamide fiber of the present invention, other than the toughness factor (TF) of the wholly aromatic polyamide fiber, except for not containing the layered clay mineral particles, the other is the wholly aromatic polyamide. The ratio TF / TFo to the toughness factor (TFo) of the comparative wholly aromatic polyamide fiber, which is all the same as the fiber, is preferably 1.1 or more.

 In the wholly aromatic polyamide fiber of the present invention, it is preferable that the layered clay mineral particles have an organic ion between the layers. In the wholly aromatic polyamide fiber of the present invention, the wholly aromatic polyamide is preferably selected from meta-based wholly aromatic polyamides.

 The method for producing a stretch-orientated wholly aromatic polyamide fiber of the present invention comprises: a solvent, a wholly aromatic polyamide, and 0.05 to 20 parts by mass based on 100 parts by mass of the wholly aromatic polyamide. The spinning dope containing the layered clay mineral particles is extruded into a fibrous form in an aqueous coagulation bath through a spinneret and spun out. The extruded fibrous stock solution is coagulated, and the formed undrawn fibers are wet-wet atmosphere. Characterized in that the drawn fiber obtained is dried and heat-treated.

 In the method for producing a wholly aromatic polyamide fiber of the present invention, the spinning dope may include a part of the solvent, a part of the wholly aromatic polyamide, and 100 parts by mass of the wholly aromatic polyamide part. Is prepared by mixing a solution A consisting of 30 to 300 parts by mass of layered clay mineral particles, and a solution B consisting of the remainder of the solvent and the remainder of the wholly aromatic polyamide; 1) and (2):

(1) solution A, shear rate 0.1 sec - viscosity at ^1, shear rate 10 15 to 80 times the viscosity in sec- ¹ ; and

(2) The viscosity of solution A should be 4 to 20 times the viscosity of solution B at a shear rate of 0.1 sec- ¹

Is preferably satisfied.

 In the method for producing a wholly aromatic polyamide fiber according to the present invention, the concentration of the wholly aromatic polyamide in the spinning dope may be 0 ::! It is preferably from 30 to 30% by mass.

 In the method for producing a wholly aromatic polyamide fiber of the present invention, it is preferable that a stretching ratio of the unstretched fiber in the wet atmosphere is in a range of 0.3 to 0.6 times the maximum stretching ratio. .

 In the method for producing a wholly aromatic polyamide fiber of the present invention, the solvent is preferably selected from amide-based polar solvents.

 In the method for producing wholly aromatic polyamide fibers of the present invention, it is preferable that the wholly aromatic polyamide is selected from meta-based wholly aromatic polyamides. Brief Description of Drawings

 FIG. 1 is an electron micrograph of a cross section of an example of the wholly aromatic polyamide fiber of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The wholly aromatic polyamide used in the present invention is one in which the aromatic rings constituting the main skeleton of the repeating unit are connected to each other by an amide bond, and particularly a meta-based wholly aromatic polyamide. It is preferable to select from the list. Such a wholly aromatic polyamide is generally produced by subjecting an aromatic dicarboxylate dihalide and an aromatic diamine to low-temperature solution polymerization or interfacial polymerization in a solution thereof. The diamine components used in the present invention include, for example, paraphenylene diamine, 2-chloroparaphenylene diamine, 2,5-dichloroparaphenylene diamine, 2,6-dichloroparaphenylene diamine, m-phenylene diamine. Diamine, 3,4 'diamino diphenyl ether, 4, 4, diamino diphenyl ether, 4, 4,-diamino diphenyl methane, 4, 4,-diamino diphenyl sulfone, 3, 3 'It is preferable to include one or more kinds such as diaminodiphenylsulfone, but it is not limited thereto. Among these diamine compounds, it is preferable to use p-phenylenediamine, m-phenylenediamine and 3,4, diamminodiphenyl ether.

 The aromatic dicarboxylic acid dihalide component used in the present invention includes, for example, dichloride isophthalate, dichloride terephthalate, dichloride 2-chloroterephthalenolate, and 2,5-dichloride. Preferably, it contains at least one of dichloride / reterephthalic acid, 2,6-dichloroterephthalic acid dichloride, and 2,6-naphthalenediphthalic acid dichloride. It is not limited to. Among these aromatic dicarboxylic acid dihalides, it is preferable to use terephthalic acid dichloride and Z or isophthalic acid dichloride.

Among the above-mentioned wholly aromatic polyamides, it is preferable to use polymethafylene disophthalamide, copolyno ヽ⁰ raphenylene · 3,4, -dioxydiphenyreneterephthalamide, and in particular, polymethafene diamide. It is preferable to use renysophthalamide.

Solvents used for preparing a spinning dope by polymerizing a wholly aromatic polyamide include, for example, N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl-12-pyrrolidine. Don and N-methylcap Organic polar amide solvents such as loractam; water-soluble ether compounds such as tetrahydrofuran and dioxane; water-soluble alcohol compounds such as methanol, ethanol and ethylene glycol; water-soluble such as acetone and methylethyl ketone A ketone compound and at least one water-soluble nitrile compound such as acetonitrile and propionitrile are used, but not limited thereto. The solvent may be a mixture of two or more of the above compounds. The solvent used in the method of the present invention is preferably dehydrated.

 In this case, an appropriate amount of a conventionally known inorganic salt may be added to the polymerization mixture before, during, or at the end of the polymerization to increase the solubility. Examples of such inorganic salts include lithium chloride and calcium chloride.

 When a wholly aromatic polyamide is produced from the diamine component and the acid halide component, the molar ratio of these diamine components to the acid halide component is 0.90 to 1.10. It is preferably controlled, more preferably 0.95 to 1.05.

 The molecular end of the wholly aromatic polyamide used in the present invention may be blocked. When an end-capping agent is used for this capping, examples of the end-capping agent include phthalic acid chloride and its substituted product, and aniline and its substituted product as the amine component.

 In general, the opposite of acid halides and diamines involves the combined use of aliphatic amines, aromatic amines, and quaternary ammonium salts to trap acids such as haploid hydride formed. be able to.

After the completion of the polymerization reaction, if necessary, a basic inorganic compound, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, or the like is added to the reaction mixture and added. Neutralize. The reaction conditions for producing the wholly aromatic polyamide of the present invention are not particularly limited. The reaction between acid halide and diamin generally proceeds rapidly, and the reaction temperature is usually -25 to 100 ° C, preferably -10 to 80 ° C.

 The wholly aromatic polyamide polymer thus obtained can be poured into a non-solvent such as alcohol or water to cause precipitation, and can be taken out as pulp-like flakes. This polymer flake can be dissolved again in a solvent and the solution can be subjected to wet spinning, but the solution obtained by the polymerization reaction can be used as it is as a spinning solution. The solvent used for the re-dissolution is not particularly limited as long as it dissolves the wholly aromatic polyamide, but it is preferable to use the solvent used for the polymerization of the above-mentioned wholly aromatic polyamide.

 Next, the layered clay mineral used in the present invention has a cation exchange ability, and further exhibits a property of swelling by taking in water between layers, and is preferably a smectite-type clay mineral and a swelling clay mineral. Mica is used. Specific examples of layered clay minerals include hematite, savonite, stevensite, paiderite, and montmorillonite as smectite-type clay minerals. And substituted compounds, derivatives or mixtures thereof. In addition, examples of the swellable mica include synthetic swellable mica which is chemically synthesized and has Li and Na ions between layers, or a substitute, derivative or mixture thereof.

In the present invention, it is preferable to use those obtained by treating the above-mentioned layered clay mineral particles with a surface treating agent (intercalating agent) containing an organic ion. By treating with the organic anion, the dispersibility of the obtained layered clay mineral particles in the wholly aromatic polyamide and matrix is improved, and the filament formation property and the toughness factor of the obtained fiber are improved. Can be improved. The organic ion used for the surface treatment is represented by the following formula (1)

I

R _x -N ⁺ -R ₃ (1)

R 4

(R _x , R ₂ , R ₃ and R ₄ are each independently an alkyl group having 1 to 30 carbon atoms or a hydroxypolyoxyethylene group represented by 1 (CH ₂ CH ₂₀ ) _n H.)

It is preferable to select from quaternary ammonium ions having the chemical structure represented by Here, among the alkyl groups having 1 to 30 carbon atoms represented by R ₂ , R ₃ and R ₄ , an alkyl group having 1 to 18 carbon atoms is preferable.

Preferred quaternary ammonium compounds include, for example, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium mouthride, hexadecinole trimethylammonium chloride. Ride, octadecyl trimethylammonium chloride, oreinoletri methinolemonium mouth lid, didodecyl / ledimethylammonium chloride, lide, ditetradecyldimethylammonium chloride mouth, lide, dihexadecyldimethylammonium chloride Demcrolide, Gio Ctadesino Resin Mesminole Ammonium Enclom Ride, Goreino Resime Mesinole Ammonium Mouth Ride, Dodecyl Jetinole Penzinole Ammonium Chloride, Tetradecyl Dimethylbenzyl Ammonium chloride Hexadecyldimethylbenzylammonium chloride, Ota tadecinoresin methinole penzinoleammonium chloride, oleinoresimetyl benzyl benzyl chloride, trioctylmethylammonium chloride, hydroxypolyoxypropylene methyl chloride Chillammonium chloride, hydroxypolyoxyethylene dodecyldimethyla Ammonium chloride, hydroxypolyoxyethylenetetradecyldimethylammonium chloride, hydroxypolyoxyethylenehexadecyldimethylammonium mouth light, hydroxypolyethyleneethyleneoctadecyldimethylammonium chloride Mouth Ride, Hydroxypolyoxyethylene Oleno Resin Methinoleammonium Mouth Ride, Dihydroxypoxypolyoxyethylene Dodecylmethyl Ammonium Mulride, Bis (Hydroxypolyoxyethylene) Tetradecine Chloride, bis (hydroxypolyoxyethylene) hexadecylmethylammonium chloride, bis (hydroxypolyoxyethylene) octadecylmethylaminomonium mouth light, and Scan (heat Dorokishipori oxyethylene) Oreirume chill ammonium Niu Solid but Rorai de like, not shall be limited thereto.

 The method of treating layered clay mineral particles with organic onion is as follows.

Usually, 1 part by weight of layered clay mineral particles and 1 to 10 parts by weight of organic anion are mixed in water, and then the mixture is dried. The amount of water used is preferably 1 to L00 times that of the layered clay mineral. The mixing temperature is preferably 30 to 70 ° C., and the mixing time is preferably 0.5 to 2 hours. As the drying conditions, 70 to: It is preferable to dry under normal pressure at L00 ° C for 3 days and then vacuum dry for 2 days.

Rights Hitoshiso thickness of the layered clay mineral particles in the wholly aromatic polyamide de fibers of the present invention is preferably not more than 500n _m, in particular less der Rukoto more preferably 200 nm. The average layer thickness of the layered clay mineral referred to here is measured for all layered clay mineral particles observed in a cross-sectional area of 25 μm ² by electron microscopic measurement (magnification 100,000 times) of the longitudinal section of the fiber. This is the average value of the layer thickness. Average layer thickness of layered clay mineral is 500nm If it is larger than this, it may be difficult to ensure the molding stability of the obtained resin composition during spinning. On the other hand, in order to disperse the layered clay mineral particles to the molecular level, it is necessary to lower the solution concentration of the spinning solution in order to secure the thickening effect and dispersibility of the layered clay mineral particles. Not only does production efficiency decrease, but the effect of improving the toughness of the resulting fiber tends to decrease. Therefore, the average layer thickness of the layered clay mineral particles is preferably 10 nm or more, and more preferably 12 nm or more. The vertical and horizontal dimensions of the layered clay mineral particles used in the present invention are preferably (50 to 1000ηιη) X (50 to: l OOOnm), and more preferably (100 to 500 nm) X ( 100 to 500 nm).

Moreover, the wholly aromatic poly Ami de fibers, disconnects along the fiber axis, the longitudinal cross section, observed with a magnification of 100,000 Ri by the electron microscope, 25 mu m ² observations sectional area S 2 In this case, when the total area S 1 of a plurality of regions where the state of the fiber cross section is changed due to the influence of the layered clay mineral particles is measured, the layered clay mineral particles defined by the following formula (1) are obtained. Of the dispersion Y in the fiber:

 Y (%) = (S1 / S2) X 100 (1) is 0 :! It is preferably within a range of from 40 to 40, and more preferably from 0.5 to 30. If the dispersity Y is less than 0.1, the improvement in the toughness factor may be small.If the dispersity Y exceeds 40, it is prepared from wholly aromatic polyamide, layered clay mineral particles and a solvent. The transparency of the spinning dope may be low, and the formability may also be low.

In the microscopic observation, the change in the fiber state observed in the cross section of the fiber indicates that the layered clay mineral particles distributed in the cross section area have a higher distribution density than the other areas. This is due to In the present invention, as described above, the wholly aromatic poly It was found for the first time that the toughness factor of the resulting fiber could be increased by interspersing the relatively high density of the layered clay mineral particles in the amorphous volma matrix. In order to moderately disperse the relatively high density distribution of the layered clay mineral particles, the dispersion degree Y of the layered clay mineral should be controlled within the range of 0 :! to 40. This can be achieved by:

 FIG. 1 shows a cross section of an example of a wholly aromatic polyamide drawn fiber of the present invention. In Fig. 1, it can be seen that multiple areas with a high density of layered clay minerals are scattered and distributed in the form of short fibers in the fiber cross section. The short fibrous region extends along the fiber axis direction.

 As described above, it is not yet sufficiently clear why the scattered distribution of regions having relatively high distribution densities of layered clay mineral particles in the fiber improves the toughness factor of the resulting fiber. However, when stretched, the area containing the layered clay mineral particles with such a high distribution density forms a network structure composed of the layered clay mineral particles and the wholly aromatic polyamide polymer molecules. Furthermore, it is assumed that this network structure is oriented along the fiber axis direction by drawing. The formation of such an oriented network structure of the layered clay mineral particles and the polymer seems to greatly contribute to the improvement of the toughness factor even if the content of the layered clay mineral particles is relatively small. .

In the present invention, a filament other than the layered clay mineral can be used together with the wholly aromatic polyamide polymer as long as the physical properties and the process stability during the spinning are not impaired. Examples of the filler used include non-fibrous fillers such as fibrous or plate-like, scaly, granular, irregular, and crushed products, but non-fibrous ones are particularly preferable. Specific examples are potassium titanate whiskers, potassium titanate whiskers, aluminum borate whiskers, and silicon nitride whiskers. Scar, my strength, talc, kaolin, silica, calcium carbonate, glass beads, glass flakes, glass microvanolane, creed, molybdenum disulfide, wallastenite, titanium oxide, zinc oxide, calcium polyphosphate, graph Examples include iron, metal powder, metal flake, metal ribbon, metal oxide, carbon powder, graphite, carbon flake, and flaky carbon. In addition, when the single-filament fineness of the wholly aromatic polyamide fiber is large, glass fiber, PAN-based or pitch-based carbon fiber, stainless steel fiber, metal fiber such as aluminum fiber or brass fiber, and wholly aromatic polyamide Organic fibers such as fibers, gypsum fibers, ceramic fibers, asbestos fibers, zirconia fibers, alumina fibers, silicon fibers, titanium oxide fibers, silicon carbide fibers, rock wool, and metal ribbons can also be used. Two or more of these fillers may be used in combination.

 In addition, the above-mentioned filler may be used by treating its surface with a known coupling agent (for example, a silane coupling agent, a titanate coupling agent, etc.) or other surface treatment agents.

 In the wholly aromatic polyamide fiber of the present invention, the layered clay mineral is contained in an amount of 0.05 to 20 parts by weight, preferably 0.:! It must be contained in an amount of from 10 to 10 parts by weight, more preferably from 0.5 to 5 parts by weight. When the content of the layered clay mineral is less than 0.05 part by weight with respect to 100 parts by weight of the wholly aromatic polyamide, no improvement in the toughness factor is observed. It is not preferable because the spinning solution comprising the clay mineral, the wholly aromatic polyamide and the solvent has low transparency and poor formability.

When the degree of orientation A of the layered clay mineral in the fiber is 50% or more, preferably 70% or more, and more preferably 80% or more, the mechanical properties (toughness factor) and thermal dimensional stability And other physical properties are improved. Good. The degree of orientation A of the layered clay mineral particles can be obtained from the following formula based on the intensity distribution measured along the Depay ring of the 001 surface reflection peak of the layered clay mineral particles measured by X-ray analysis. .

 A = (180-w) / 180 X 100

Here, w represents the half width (degree) of the intensity distribution measured along the Depay ring of the reflection peak.

Except that the wholly aromatic polyamide fiber of the present invention does not contain a layered clay mineral, the other is completely the same as the comparative wholly aromatic polyamide fiber, which is exactly the same as the above-mentioned wholly aromatic polyamide fiber. Preferably, the tensile strength (T) is improved by 10% or more, and the elongation (E) is preferably improved by 10% or more. Further, the toughness factor (TF) is improved by 10% or more, particularly 20% or more, and it is preferable that the toughness factor (TF) has 30 or more. Here, the toughness factor (TF) is defined as the square root of the tensile strength (Τ ') measured in grams / denier and the elongation ()) expressed in%. Product, that is, Τ 'X (Ε) ^1/2 .

 When the toughness factor is increased to 30 or more in this manner, even if the draw ratio is increased to improve the strength of the fiber, breakage of single yarn in the fiber is reduced (improvement of quality), and the fiber is drawn to a drawing roller or the like at the time of drawing. The winding of the single yarn is reduced (improvement of process stability). In particular, when the improvement in the toughness factor is 10% or more, the effect of stabilizing the stretching step is increased, which is preferable.

 Further, the wholly aromatic polyamide fiber of the present invention may contain other components, for example, an antioxidant, a heat stabilizer, a weathering agent, a dye, an antistatic agent, a flame retardant, as long as the effects of the present invention are not impaired. It may contain conductive agents and other additives.

The wholly aromatic polyamide fiber of the present invention can be produced, for example, by the following method. (1) wholly aromatic polyamide, layered A process of preparing a spinning dope comprising a clay mineral and a solvent,

(2) a step of spinning the raw spinning solution into an aqueous coagulation bath and coagulating; (3) a step of drawing the coagulated yarn in a wet atmosphere; and (4) a step of drying and heat treating the drawn yarn. Can be manufactured.

 The mixing ratio of the layered clay mineral to the wholly aromatic polyamide in the spinning solution is 0.05 to 20 parts by mass, preferably 0.1 to 10 parts by mass, particularly preferably 0.1 to 10 parts by mass for the former 100 parts by weight. It is controlled in the range of 0.5 to 5 parts by mass. Further, the polymer concentration in the spinning dope is preferably 0.1 to 30% by mass, more preferably 1 to 25% by mass, and still more preferably 15 to 25% by mass. Further, the haze of the spinning dope is preferably adjusted to 10 or less, more preferably 5 or less.

 There is no limitation on the method for preparing the spinning stock solution. For example, (A) a method of adding a layered clay mineral to a solution of a wholly aromatic polyamide, (B) a solution of a solution of a whole aromatic polyamide and a solution of a layered clay mineral. There are a method of mixing with a dispersion, and a method of adding and dispersing a wholly aromatic polyamide to a solution of (C) a layered clay mineral.

 When preparing the spinning dope used in the present invention from a wholly aromatic polyamide polymer, layered clay mineral particles and a solvent, a part of the above-mentioned solvent, a part of the above-mentioned wholly aromatic polyamide polymer, this wholly aromatic polyamide polymer part 100 A solution (A) consisting of 30 to 300 parts by mass of the layered clay mineral particles with respect to parts by mass is separately prepared. Separately, a solution B is prepared from the remainder of the solvent and the remainder of the wholly aromatic polyamide polymer. Then, the solution A and the solution B are mixed, and at this time, the solution A and the solution B are as follows:

(1) The viscosity of the solution A at a shear rate of 0.1 second- ¹ is 15 to 80 times the viscosity at a shear rate of 10 seconds- ¹ .

(2) At a shear rate of 0.1 s- ¹ , the viscosity of solution A is 4 to 20 times

It is preferable to prepare so as to satisfy the following.

 By doing so, the region where the distribution density of the layered clay mineral particles is relatively high in the spinning dope can be evenly dispersed and distributed, and the spinning process is stabilized and the layered clay mineral in the fiber obtained is obtained. By controlling the degree of dispersion Y of the particles to a desired value, the effect of improving the toughness factor of the obtained fiber can be increased.

 Here, when the ratio of the layered clay mineral to the wholly aromatic polyamide in the solution A is less than 30 parts by weight, the viscosity difference from the solution B becomes small, and the layered clay mineral is uniformly dispersed in the obtained spinning solution. The effect of improving the toughness factor may be reduced. On the other hand, if it exceeds 300 parts by weight, the distribution density of the layered clay mineral becomes extremely non-uniform, which may lower the stability of the spinning process.

Also, when the viscosity of the solution A at a shear rate of 0.1 sec- ¹ is less than 4 times the viscosity of the solution B, the layered clay mineral is easily dispersed uniformly, and therefore, the relatively large distribution density of the layered clay mineral particles In some cases, the effect of improving the toughness factor may be reduced, and if it exceeds 20 times, the region where the distribution density of the layered clay mineral particles in the spinning dope is relatively high in the spinning process. Is excessively formed, which may cause an increase in pack pressure or the like, thereby deteriorating the process stability. Furthermore, when the viscosity of the solution A at a shear rate of 0.1 second- ¹ is less than 15 times the viscosity at a shear rate of 10 seconds- ¹ , the layered clay mineral is easily dispersed evenly in the fiber. However, the formation of a region having a relatively large distribution density of the layered clay mineral particles is reduced, and the effect of improving the toughness factor is reduced. On the other hand, if it exceeds 20 times, the layered clay mineral particles in the spinning dope during the spinning process The formation of a region having a relatively high distribution density becomes excessive, and therefore, the process stability may decrease. The solvent used for preparing the spinning solution is not particularly limited as long as it can dissolve the wholly aromatic polyamide, but it is preferable to use an amide-based polar solvent as a main component. For example,

N-methyl-1-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylformamide, tetramethylurea, hexamethylphosphoramide, N — Nonprotonic amide-based organic solvents such as methylbutyrolactam. The temperature of the undiluted spinning solution may be appropriately set according to the solubility of the wholly aromatic polyamide, but in the case of polymethaphenylene sophthalamide, the spinning ability should be set within the range of 50 to 90 ° C. This is preferred from the viewpoint of

 In the method of the present invention, the undiluted fiber is formed by spinning the spinning dope into a filament, for example, directly into an aqueous coagulation bath, and coagulating it, usually from a spinneret having 10 to 30,000 discharge holes. The composition of the aqueous coagulation bath used here is not particularly limited, and may be appropriately selected depending on the type of the wholly aromatic polyamide and the solvent to be used, and may be a conventionally known aqueous solution containing an inorganic salt and Z or a solvent. Coagulation bath solutions can be used. Specifically, when the wholly aromatic polyamide is polymetaphenylene isophthalamide and the solvent is N-methyl-2-pyrrolidone (NMP), the calcium chloride concentration is 34 to 42% by weight, the NMP An aqueous solution having a concentration of 3 to 10% by weight is exemplified as a preferable example. In this case, the temperature of the aqueous coagulation bath is suitably in the range of 80 to 95 ° C, and the time of immersing the fiber in the coagulation bath is suitably in the range of 1 to 11 seconds.

Since a considerable amount of solvent remains in the undrawn fiber drawn out of the coagulation bath, it is preferable to wash the undrawn fiber with water to extract and remove the residual solvent. For example, a method of passing undrawn fibers drawn from a coagulation bath through a water bath, a method of spraying water on the undrawn fibers, and the like are adopted. Here, the solvent content in the fibers after washing is controlled to 30% by weight or less. If the ratio exceeds this range, water easily penetrates into the fibers in the next drawing step, and voids are generated to reduce the fiber strength and make the fibers weak.

 The undrawn fibers washed with water are drawn in a wet atmosphere, preferably in a warm water bath, and at the same time, the remaining solvent and, if necessary, inorganic salts such as calcium chloride are washed away. . The stretching temperature in the stretching is appropriately set according to the amount of the solvent remaining in the undrawn fiber. For example, when the residual amount of the solvent is 50% or more relative to the mass of the polymer, it is preferable to control the stretching temperature to 0 to 50 ° C. If it is less than 50%, it is preferable to control the stretching temperature to 50 to 100 ° C. The draw ratio is preferably 1.05 times or more, more preferably 1.10 times or more, and still more preferably the maximum draw ratio of undrawn fibers (the yarn breakage occurs when drawn under the same drawing conditions). (The starting draw ratio) is controlled in the range of 0.3 to 0.6 times.

 The obtained drawn fiber is usually dried at a temperature of 100 ° C. or higher, and then, if necessary, further hot drawn, and then heat-treated by a heating roller, a hot plate or the like.

 The thus obtained wholly aromatic polyamide fiber is collected as a tow as required, or wound up, or sent directly to a post-process, and if necessary, crimped. After being cut, it is cut and provided as short fibers for the subsequent desired steps. Example

 Hereinafter, the present invention will be described more specifically with reference to examples. Each characteristic value in the examples was measured by the following method.

<Intrinsic viscosity IV> The test polymer was dissolved in NMP at a concentration of 0.5 g ZOO ml, the viscosity of this solution was measured at 30 ° C using an Ostwald viscometer, and the intrinsic viscosity was calculated from the measured value. .

 <Viscosity>

 The viscosity of the spinning solution was measured at 70 ° C. using a viscometer (trade name: Reomat 115) manufactured by Rheometric Scientific.

 <Fineness>

 It was measured according to JIS-L-1015.

 <Tensile strength, elongation>

 The measurement was performed according to JIS-L-1015 at a sample length of 20 mm, an initial load of 0.05 g / dt ex, and an extension speed of 20 mm / min.

 <Orientation degree of layered clay mineral A>

 Using an X-ray generator (RU-200B manufactured by Rigaku Denki Co., Ltd.), measurement was performed under the conditions of a target CuK α ray, a voltage of 45 kV, and a current of 70 mA. Incident X-rays were condensed and monochromated by an Osmic multilayer mirror, and fiber samples were measured by the vertical transmission method. X-ray diffraction was measured using a 200 mm x 250 mm imaging plate (Fuji Photo Film) with a camera length of 250 mm. The degree of orientation A of the clay layer surface was determined by the following equation from the intensity distribution measured along the Debye ring of the 001 surface reflection peak.

Where w is the half width (degrees) of the intensity distribution measured along the Depay ring of the reflection peak.

 <Haze of spinning stock solution>

 Using a turbidity meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd., the haze of the spinning stock solution filled in a cell having an optical path length of 1 cm was measured.

 <Average layer thickness of layered clay mineral particles>

Permeability of fiber longitudinal section measured using Hitachi H-800 electron microscope Over type electron micrograph (TEM photograph, magnification of 100,000) the layer thickness of all of the layered clay mineral particles observed in the cross-sectional area ₂₅ μ πι ² in measure, and the average value was calculated.

 <Degree of dispersion of layered clay mineral (Υ)>

The wholly aromatic polyamide fiber was cut along the fiber axis, and the longitudinal section was observed with a transmission electron microscope (model: Η-800) manufactured by Hitachi, Ltd. at a magnification of 100,000 to obtain a 25 μm When the total area S 1 of a plurality of regions in which the state of the fiber cross-section changes due to the influence of the layered clay mineral particles was measured per observation cross-sectional area S ² of m ^2, the following equation (1) was obtained. The dispersion Y of the layered clay mineral particles defined in the fiber in the fiber was calculated by the following equation.

 Y (%) = (S 1 / S 2) X10O

 The above was measured three times, and the average value was obtained.

 <Shear viscosity of solution>

 The shear viscosity of the solution at the time of preparing the spinning stock solution was measured at a temperature of 70 ° C. using a rheomat 115 manufactured by Rheometrics Scientific.

 <Solvent content in fiber N>

 The fiber before drawing is centrifuged at 5000 rpm for 10 minutes, and then the fiber is boiled in methanol for 4 hours to extract the solvent and water in the fiber. The methanol solution weight M2 after extraction and the dry weight Ml of the fiber were measured, the solvent weight concentration C (%) in the extract was determined by gas chromatography, and the solvent content N was calculated by the following formula. Calculated.

 N = (C / 100XM 2) / M 1 X 100

 <Number of single fibers>

A plurality of the drawn fibers are drawn together to form a fiber bundle, one end of the fiber bundle is fixed, and cut so that the length of the other end from the fixing portion is 20 cm. Let H be the total number of filaments at this time. Next, this fiber bundle After making 10 reciprocations in the vertical direction in a path filled with water (length 0.5m), the fiber bundle is pulled up, and the single yarn remaining in the path is counted. This operation is repeated 5 times, and the sum is M. The number of single fiber breaks (X) in 15000 m was calculated by the following formula, and this was repeated three times to obtain an average value.

 X = M X 15000 / (H X T X 0.2)

Example 1

215 g of polymetaphenylene isophthalamide having an intrinsic viscosity of 1.35 dl / g was dissolved in 785 g of NMP and stirred until a uniform transparent dope was obtained. Separately, a layered clay mineral, Poriokishipuro pyrene methyl Jefferies chill en Moniumukurorai de treated with Sumekutai preparative clay minerals (trademark Rusentai preparative SPN, manufactured by Co-op Chemical), and 1 weight ⁰ /. Was mixed with and dispersed in the marauder P so as to obtain a concentration. The obtained layered clay mineral dispersion was added to the wholly aromatic polyimide solution so as to have the composition shown in Table 1, and stirred to prepare a spinning dope (dope). The haze of the obtained dope was 2.41. After defoaming the obtained dope, it was extruded into a filament form from a die having a cap diameter of 0.07 mm and a number of holes of 100, and a 43% aqueous solution of calcium chloride at 85 ° C (containing 1 mass./. NMP). And then coagulated at a spinning speed of 7 mZ, washed with water, stretched the undrawn fiber 2.4 times in boiling water, dried at 120 ° C, and dried at 350 ° C. A 1.75-fold stretching heat set was performed at ° C. A wholly aromatic polyamide fiber containing a layered clay mineral was obtained. When the longitudinal section of the single fiber was measured by TEM, the average layer thickness of the layered clay mineral particles was 90 nm. The degree of orientation A of the layered clay mineral particles obtained from the X-ray diffraction results was 91%. Tensile strength, elongation, and toughness factor of the obtained fiber

(TF) is shown in Table 1.

Example 2 In the same manner as in Example 1, a wholly aromatic polyamide fiber having the composition shown in Table 1 was produced. However, as the layered clay mineral, a smectite-type layered clay mineral (trade name: Lucentite STN, manufactured by Corp Chemical) treated with trioctylmethylammonium-mum chloride was used. The haze of the spinning dope at this time was 1.92. The average layer thickness of the layered clay mineral particles was 86 nm, and the degree of orientation A was 91%. Table 1 shows the tensile strength, elongation, and toughness factor (TF) of the obtained fiber.

 In the same manner as in Example 1, a wholly aromatic polyamide fiber was produced.た However, layered clay minerals were not included. Table 1 shows the tensile strength, elongation, and toughness factor (TF) of the obtained fiber.

 table 1

Example 3

0.16 parts by mass of an intrinsic viscosity of 1.9 dl / g of polymethaphenylene isophtalamide was dissolved in 1.46 parts by mass of NMP and stirred until a uniform transparent dope was obtained. To this dope, as a layered clay mineral, 0.18 parts by mass of a smectite-type layered clay mineral (trade name: Lucentite SPN, manufactured by Corp Chemical) treated with polyoxypropyl pyrene methyl getyl ammonium hydroxide mouth light was added. Then, the mixture was stirred to prepare a polymer solution A. Separately Then, 17.44 parts by mass of polymethafenylenisophthalamide was dissolved in 63.68 parts by mass of a marauder to prepare a transparent polymer solution B.

 After mixing and stirring the polymer solution A and the polymer solution B, 17.08 parts by mass of NMP is further added to the mixed solution, whereby 17.60 parts by mass of polymetaphenylene sophthalamide is added, and Rucentite SPN (trademark) ) A spinning dope was prepared comprising 0.18 parts by mass and a marble P82.22 parts by mass.

 This spinning stock solution was heated to 85 ° C, extruded in a filament form from a spinneret having a pore size of 0.07 mm and a number of holes of 1500, and introduced into a coagulation bath at 85 ° C to produce an undrawn fiber. The composition of the coagulation bath is as follows: calcium chloride: 40% by mass, NMP: 5% by mass, water: 55% by mass, immersion length (effective coagulation bath length) is 100 cm, and unstretched fiber has a speed of 7. O m After passing through in Z minutes, it was immediately pulled out into the air. The solidified unstretched filaments were sequentially washed with water in the first to third aqueous washing baths. The total immersion time in this washing was 50 seconds. Water at a temperature of 30 ° C. was used for the first to third aqueous washing baths. Next, the unstretched washed film is stretched 2.4 times in hot water of 95 ° C, then immersed in hot water of 95 ° C for 48 seconds, washed, and then rolled at a surface temperature of 130 ° C. After being subjected to dry heat treatment, it was stretched 1.75 times while being in contact with a hot plate having a surface temperature of 330 ° C to produce poly (metaphenylene isophthalamide fiber). The fineness was 2.26 dt ex, the tensile strength was 5.16 cN / dt ex, and the elongation was 43.2%. The maximum draw ratio in the above hot water drawing process was 4.7 (the draw ratio Z The stretching ratio was 0.51), and the solvent content before stretching was 5.0 parts by mass with respect to 100 parts by mass of the wholly aromatic polyamide.

In addition, the number of broken single fibers in the spinning and drawing step was 6 per 15000 m in length, and the degree of dispersion Y of the layered clay mineral was 3%. Table 2 shows the test results. Example 4

 0.32 parts by mass of the same polymetaphenyleneisophthalamide powder as in Example 3 was dissolved in 6.46 parts by mass of NMP cooled to 110 ° C to prepare a transparent polymer solution. To this, 0.72 parts by mass of a smectite-type clay mineral (trade name: Lucentite SPN, manufactured by Corp Chemical) was added as a layered clay mineral, followed by stirring to prepare a polymer solution A. Separately, 13.28 parts by mass of a polymetaphenylene isophthalamide powder was dissolved in 48.49 parts by weight of NMP cooled to -10 ° C to prepare a transparent polymer solution B.

 After mixing and stirring the polymer solution A and the polymer solution B, 30.73 parts by mass of NMP is further added to the mixed solution, whereby 17.60 parts by mass of polymetaphenylene sophthalamide is added, and Lucentite SPN (trademark) 6.) A spinning dope consisting of 80 parts by mass and P75.6 parts by mass was obtained.

The spinning solution was subjected to spinning and elongation under the same conditions and operations as in Example 3 to obtain a single fiber fineness of 2.18 dt ex, a tensile strength of 6.03 cN / dt ex, and an elongation of 45.3%. Lenisophthalamide fiber was produced. The number of broken single fibers in the spinning and drawing step was 10 per 15,000 m in length, and the degree of dispersion Y of the layered clay mineral was 25%. Table 2 shows the test results.

Table 2 Example 3 Example 4

)

/ 0 1.0 4 0 iV-V of Ar. No I S., before Hff; 亩 U. ¹ poise) 7 0

Shear rate 10 sec- ¹ poise 90 Viscosity of solution ：: Shear rate 0.1 sec- ¹ poise) 420

Fineness 2 26 IS Tensile strength (cN / dtex) 5.17 5 2

 Elongation% 43.2 45.3 Toughness factor (TF) 38.5 40.6 Number of broken single fibers (pieces / 15000m) 6 10 Dispersity Υ (%) 3 25

*: Based on the mass of wholly aromatic polyamide. Example 5

 Spinning and stretching were performed under the same conditions and operations as in Example 3. However, the same spinning dope as in Example 3 was used, but the hot water draw ratio was 2.8 times and the 330 ° C hot plate draw ratio was 1.50 times. Polymetaphenylene sophthalamide fibers having a single fiber fineness of 2.22 dtex, a tensile strength of 5.49 cN / dtex and an elongation of 40.7% were obtained.

 The maximum stretching ratio in the hot water stretching step was 4.7 (stretching ratio Z maximum stretching ratio = 0.60), and the solvent content of the fiber before stretching was 5.0 parts by mass with respect to 100 parts by mass of the wholly aromatic polyamide. Was.

 Also, the number of broken single fibers of this fiber was 8 per 15000 m. Table 3 shows the test results.

Example 6 Spinning and stretching were performed under the same conditions and operations as in Example 3. However, the spinning solution of Example 3 was used, but the washing time before hot water drawing was set to 34 seconds. A fiber having a single fiber fineness of 2. 21 dt ex, a tensile strength of 6.12 cNZ dt ex, and an elongation of 48.3% was obtained.

 The maximum stretching ratio in the hot water stretching step is 4.9 (the maximum stretching ratio is 0.49) .The solvent content of the fiber before stretching is 14 parts per 100 parts by mass of the wholly aromatic polyamide. 0 parts by weight.

 In the spinning and drawing step, the number of broken single fibers was 2 per 15000 m. Table 3 shows the test results.

 Table 3

 *: Based on the weight of wholly aromatic polyamide.

 **: Content per 100 parts by mass of wholly aromatic polyamide Industrial applicability

The wholly aromatic polyamide fiber of the present invention has a higher mechanical strength, a lower degree of toughness and a higher toughness factor than conventional laminar clay mineral-free fibers. As described above, it can be suitably used for various applications utilizing these characteristics. In addition, according to the production method of the present invention, single-fiber breakage during spinning and drawing is reduced, and fibers of stable quality can be produced industrially and stably.

Claims

δ 冃

1. Matrix composed of wholly aromatic polyamide polymer, and layered clay mineral particles dispersed and distributed in the matrix at a ratio of 0.05 to 20 parts by mass with respect to 100 parts by mass. A stretch-orientated wholly aromatic polyamide fiber, characterized by comprising a resin composition containing:

 2. The wholly aromatic compound according to claim 1, wherein a plurality of regions having a relatively high distribution density of said layered clay mineral particles are scatteredly distributed in said wholly aromatic polyamide matrix. Polyamide fiber.

3. The wholly aromatic polyamide fiber is cut along its fiber axis, and the longitudinal section is observed with an electron microscope at a magnification of 100,000, and the observed sectional area S 2 at 25 zm ² is When the total area S1 of a plurality of regions in which the state of the fiber cross section is changed due to the influence of the layered clay mineral particles is measured, the area of the layered clay mineral particles defined by the following formula (1) is determined. The degree of dispersion Y in the fiber:

 The wholly aromatic polyamide according to any one of claims 1 or 2, wherein Y (%) = (S1 / S2) X100 (1) is in a range of 0.1 to 40. Fiber.

 4. The layered clay mineral according to any one of claims 1 to 3, wherein the layered clay mineral includes at least one selected from hectrite, savonite, stevensite, paiderite, montmorinite, and swelling mica. Item 7. The wholly aromatic polyamide fiber according to any one of the above items.

 5. The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein the layered clay mineral particles have been treated with an intercalating agent.

6. The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein the average layer thickness of the layered clay mineral particles is 10 to 500 nm.

7. The degree of orientation A of the layered clay mineral particles defined by the following formula (2):

 A (%) = [(180-w) / 180] X100 (2) (伹) In equation (2), in the X-ray analysis of the layered clay mineral particles, the (001) surface of the layered clay mineral particles The half-width of the measured intensity distribution is shown on the depay ring of the reflection peak.

The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein the total aromatic polyamide fiber is 50% or more.

 8. Except that the tensile strength (T) of the wholly aromatic polyamide fiber does not contain the above-mentioned layered clay mineral particles, the others are exactly the same as the above wholly aromatic polyamide fiber. Polyamide fiber The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein the ratio (TZTo) to the tensile strength (To) is 1,1 or more.

 9. Except that the elongation rate (率) of the wholly aromatic polyamide fiber does not contain the above-mentioned layered clay mineral particles, the others are exactly the same as those of the wholly aromatic polyamide fiber. The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein a ratio (ΕΖΕο) force S to the tensile elongation (率 ο) of the aromatic polyamide fiber is 1.1 or more.

 10. Toughness factor (TF) of the wholly aromatic polyamide defined by the following formula (3):

TF = T 'XE' ^1/2 (3)

(In the above formula (3), T ′ represents the numerical value of the tensile strength of the wholly aromatic polyamide fiber in g / l.ldtex unit, and E ′ represents the tensile strength of the wholly aromatic polyamide fiber in% unit. 4. The whole aromatic polyamide fiber according to any one of claims 1 to 3, wherein the total aromatic polyamide fiber has a value of 30 or more.

11. Except for not containing the layered clay mineral particles, the toughness factor (TF) of the wholly aromatic polyamide fiber is the same as that of the wholly aromatic polyamide fiber except for the comparative wholly aromatic polyamide fiber. The wholly aromatic polyamide fiber according to claim 10, wherein the ratio (TFZ TFo) to the toughness factor (TFo) of the amide fiber (TFo) is 1.1 or more.

 12. The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein the layered clay mineral particles have an organic ion between the layers.

 13. The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein the wholly aromatic polyamide is selected from meta-based wholly aromatic polyamides.

 14. A spinning dope containing a solvent, a wholly aromatic polyamide, and 0.05 to 20 parts by mass of a layered clay mineral particle with respect to 100 parts by mass of the wholly aromatic polyamide is subjected to aqueous coagulation through a spinneret. The extruded fibrous stock solution is solidified by extruding into a fibrous bath and spinning, the obtained unstretched fiber is stretched in a wet atmosphere, and the obtained stretched fiber is dried and heat-treated. A method for producing a stretch-orientated wholly aromatic polyamide fiber.

 15. The spinning dope comprises a part of the solvent, a part of the wholly aromatic polyamide, and 100 parts by mass of the wholly aromatic polyamide portion, and 30 to 300 parts by mass of layered clay mineral particles. And a solution B consisting of the remainder of the solvent and the remainder of the wholly aromatic polyamide, and prepared by mixing the following requirements (1) and (2):

(1) a shear rate of solution A 0. 1 sec - viscosity at ¹ that is 15 to 80 times the viscosity at a shear rate of 10 seconds one ^1, and

(2) The viscosity of solution A should be 4 to 20 times the viscosity of solution B at a shear rate of 0.1 sec- ¹ The method for producing a wholly aromatic polyamide fiber according to claim 14 or 15, which satisfies the following.

 16. The method for producing a wholly aromatic polyamide fiber according to claim 14 or 15, wherein the concentration of the wholly aromatic polyamide in the spinning dope is 0.1 to 30% by mass.

 17. The stretch ratio for the undrawn fiber in the wet atmosphere is within the range of 0.3 to 0.6 times the maximum draw ratio, The wholly aromatic poly- lylate according to claim 14 or 15. A method for producing amide fibers.

 18. The method for producing a wholly aromatic polyamide fiber according to claim 14, wherein the solvent is selected from amide-based polar solvents.

 19. The method for producing a wholly aromatic polyamide fiber according to claim 14 or 15, wherein the wholly aromatic polyamide is selected from a meta-based wholly aromatic polyamide.