Meta-type wholly aromatic polyamide filaments and process for producing same

Meta-type wholly aromatic polyamide fiber and preparation method thereof

Technical field

The present invention relates to the use of a wet spinning method for producing a meta-type phenylenediamine m-xylylenediamine unit having high mechanical properties, heat resistance, etc. as a main repeating unit. A method for producing a polyamide fiber and a wholly aromatic polyamide fiber obtained by the method.

Background technique

The wholly aromatic polyamine obtained by polycondensing an aromatic diamine and an aromatic dicarboxylic acid dichloride is excellent in heat resistance and is excellent in flame resistance. Further, the above-mentioned wholly aromatic polyamine is soluble in the solvent of the polyfluorene compound, thereby preliminarily dissolving the polymer solution in the solvent, by dry spinning, wet spinning, semi-dry and semi-wet spinning The method of making fibers is also known.

Among the above-mentioned wholly aromatic polyamines, a fiber of a meta-type wholly aromatic polyamine (hereinafter referred to as "methacrylamide") represented by poly(phenylene phthalamide) The above-mentioned heat-resistant and flame-resistant methacrylamide fibers which are particularly useful as heat-resistant and flame-resistant fibers are now mainly manufactured according to the following two methods (a) and (b) for industrial scale manufacturing. Known.

(a) in N,N-dimethylacetamide; by using methyl phenyldiamine and chlorinated isophthalic acid for low temperature solution polymerization to prepare poly(phenylene isophthalate) The guanamine solution is used to neutralize the hydrochloric acid by-produced by the solution, and the calcium chloride-containing polymer solution is formed by dry spinning to produce poly(phenylene isophthalate). Formamide fiber The method (refer to Japanese Patent Publication No. Sho 35-14399, and U.S. Patent No. 336059).

(b) a polymerization reaction system obtained by polycondensation of an exophenylene diamine salt and a chlorinated isophthalic acid to form an organic solvent (for example, tetrahydrofuran) which is not a good solvent containing the desired polyamine An inorganic acid accepting agent is mixed with an aqueous solution of a water-soluble neutral salt to form a powder of a poly(phenylene isophthalamide) polymer, and the polymer powder is separated from the mixed system (see Japanese Japanese Patent Publication No. Sho 47-10863), after dissolving the separately polymerized powder in a solvent of a guanamine compound, wet-drawing the polymer solution in an aqueous coagulation bath containing an inorganic salt The method (refer to Japanese Laid-Open Patent Publication No. SHO 48-17551), and the method (a) and (b) other than the above-mentioned methods (a) and (b), are the following methods (c) to (f) provide.

(c) dissolving the inter-aromatic amide synthesized by solution polymerization in a guanamine solvent and preparing the aromatic amide solution without containing an inorganic salt or containing a small amount (2 to 3%) of lithium chloride. A method of forming a fiber or the like by a wet molding method (see Japanese Laid-Open Patent Publication No. SHO-50-52167).

(d) performing solution polymerization in a guanamine solvent, neutralizing the resulting m-ammonium amide solution with calcium hydroxide or calcium oxide, and containing the aromatic guanamine polymer solution between the calcium chloride and water formed therefrom The orifice is squeezed into the gas, the pre-extruded fibrous polymer solution is passed through the gas, and then introduced into the aqueous coagulation bath and solidified into a fibrous shape. Secondly, the fibrous solidified body is passed through calcium chloride or the like. a method for producing fibers in an aqueous solution of an inorganic salt (see Read Japanese Patent Laid-Open No. 56-31009.

(e) performing solution polymerization in a guanamine-based solvent, neutralizing the resulting aqueous aromatic guanamine solution with calcium hydroxide or calcium oxide, and polymerizing the calcium chloride formed therefrom and the aromatic amide at the water. A method of forming a fiber by injecting a solution into an aqueous coagulation bath containing a high concentration of calcium chloride, and forming a fiber (see Japanese Patent Laid-Open No. Hei 8-074121, No. Hei 10-88421, etc.).

(f) Dissolving a solution of a guanamine-based solvent containing an inorganic salt of an aromatic amide to a high-temperature spinning barrel, and extracting the obtained meta-aramid fiber from a spinning cylinder, and then using a low temperature The aqueous solution is cooled and swelled with water, and the water-swelled meta-aramid fiber is stretched in an aqueous stretching bath containing a plasticizable salt, thereby producing a fine pores with a fineness of less than 1.3 and easy dyeing. A method of porous fiber (refer to Japanese Patent Publication No. Sho 52-43930).

The above method (a) is advantageous in that the polymer system has a polymer solution (spinning stock solution) for spinning, and the dry spinning method using a higher boiling point guanamine solvent is used. Since it is used, the energy cost required for manufacturing is high, and if the number of holes per spinning spinneret is increased, there is a disadvantage that the spinning stability is rapidly lowered. Further, even when the polymer solution is wet-spun in an aqueous coagulation bath, only weak fibers having a large amount of devitrification can be obtained. Therefore, there is still a lot of difficulty in the wet spinning of the aqueous aromatic amide polymer solution obtained by solution polymerization using an aqueous coagulating liquid. This wet spinning method has not yet been implemented on an industrial scale.

On the other hand, in the methods (b) and (c), the problem of the dry spinning of the above method (a) can be avoided, but the compactness of the structure of the obtained fiber is unsatisfactory.

In the method (d), when the spinning spinneret is drawn into the air, if the number of holes of each of the spinning spinnerets is increased, the spinning stability is remarkably lowered, so the productivity is low. And inefficient.

Further, although the method (e) imparts good physical properties, it is difficult to increase the spinning speed, so that there is a problem of low productivity.

The method (f) is a method of producing a porous fiber having a density which is relatively small by 1.3, and is only a technique of the dry spinning method, which has the same problems as the dry drawing.

Further, the interfacial amide fiber is used for the use of an electronic material because of its excellent heat resistance and insulation properties. However, in this case, it is required to minimize the contamination of ionic substances and the like by using it as an electronic material. When possible, it is preferable to completely exclude inorganic ionic substances. However, in the manufacturing method known so far, in the spinning process, the polymer such as calcium chloride or lithium chloride is doped in the spinning stock solution or the coagulation bath, and the affinity is also high, and the content is contained at a relatively high concentration. Dissolved salts are inevitable. Therefore, there is an inevitable problem that a large amount of salt is contained in the manufactured fiber. Therefore, in order to remove the salt remaining in the fiber, it is necessary to apply a large-scale water washing step to the fiber. Even so, it is extremely difficult to completely remove the salt of the fiber.

Therefore, practically satisfactory fiber properties can be obtained, and if necessary, high-productivity can be used to produce an indole amide fiber which does not completely contain a salt. The development of novel methods is expected.

Invention disclosure

The main object of the present invention is to provide a novel method for producing a salt-free partial aromatic amide fiber which is excellent in mechanical properties and thermal properties, has a dense structure, and can be produced on an industrial scale as necessary. A dense inter-aramid fiber obtained by this method.

The method for producing an aromatic guanamine fiber according to the present invention comprises dissolving a mono-type wholly aromatic polyamine in a solvent containing a meta-phenylenediamine m-xylyleneamine unit as a main repeating unit in a solvent of a guanamine compound. And the step of preparing a polymer solution, the step of supplying the polymer solution to the wet spinning step and forming the undrawn fiber, the step of stretching the undrawn fiber, the step of washing the obtained drawn fiber, and the heat treatment The step of pre-washing the fiber to

(1) In the wet spinning step, the polymer solution is passed through a spinning nozzle of a spinning spinneret, and is discharged into a fiber-like solvent and water containing a guanamine compound without substantially containing a salt. In the coagulation bath, the flow of the pre-discharged fibrous polymer solution is solidified in the coagulation bath to form a solidified porous undrawn fiber.

(2) In the above stretching step, the above-mentioned solidified porous undrawn fiber is stretched in a plasticizable stretching bath containing an aqueous solution of a guanamine compound solvent.

The method for producing an intertype-type wholly aromatic polyamide fiber according to the present invention, which comprises the molar amount of the meta-phenylenediamine m-xylyleneamine unit of the meta-type wholly aromatic polyamine, The total amount of repeating units is It is 90~100% by mole.

In the wet spinning step of the method for producing a meta-type wholly aromatic polyamide fiber according to the present invention, the mixing ratio of the solvent of the guanamine compound to water in the coagulation bath is preferably 50/50 to 70/ 30.

In the wet spinning step of the method for producing a meta-type wholly aromatic polyamide fiber according to the present invention, the density of the solidified porous undrawn fiber is controlled to be 0.3 to 1.0 g/cm.³It is appropriate.

In the method for producing a meta-type wholly aromatic polyamide fiber according to the present invention, the weight ratio of the solvent of the guanamine compound to water in the stretching bath is preferably in the range of 20/80 to 70/30.

In the method for producing a meta-type wholly aromatic polyamide fiber according to the present invention, the stretching step, the temperature of the stretching bath is 20 to 90 ° C, and the stretching ratio of the solidified porous fiber is 1.5. ~10.

In the heat treatment step of the method for producing a meta-type wholly aromatic polyamide fiber according to the present invention, the pre-stretched, water-washed fiber is at a temperature in the range of 250 to 400 ° C, and is stretched at 0.7 to 4.0. The magnification is further stretched.

In the method for producing a meta-type wholly aromatic polyamide fiber according to the present invention, the guanamine compound solvent contained in the polymer solution and the guanamine compound solvent contained in the coagulating liquid are each independently N It is preferred to select at least one of methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide, and dimethylimidazolidinone.

In the method for producing a meta-type wholly aromatic polyamide fiber according to the present invention, the preheated fiber preferably has a density of 1.2 or more.

The polymer solution of the wet spinning step in the method for producing a meta-type wholly aromatic polyamide fiber of the present invention, the total content of the inorganic ionic substance contained in the solution is controlled to be less than 0.1% by weight can also be used.

The polymer solution for the wet spinning step of the method for producing a meta-type wholly aromatic polyamide fiber of the present invention is carried out in a solvent of a guanamine compound to form an aromatic diamine compound and a chlorinated aromatic compound The carboxylic acid is polycondensed, and is obtained by neutralizing by-produced hydrogen chloride with an alkaline calcium compound, and may contain a meta-type wholly aromatic polyamine, calcium chloride or water.

The meta-type wholly aromatic polyamide fibers of the present invention are produced by the method of the present invention described above.

The meta-type wholly aromatic polyamide fiber of the present invention has 1.2 g/cm³The above density is suitable.

The meta-type wholly aromatic polyamide fiber of the present invention is used in the polymer solution for the wet spinning step of the method of the present invention, and the total content of the inorganic ionic substance contained in the solution is controlled to be If it is 0.1% by weight or more, it can be obtained.

In the meta-type wholly aromatic polyamide fiber, the total content of the inorganic ionic substances contained in the fibers is preferably 500 ppm or less.

In the meta-type wholly aromatic polyamide fiber, the total content of calcium contained in the fiber is preferably 100 ppm or less.

In the meta-type wholly aromatic polyamide fiber, the total content of the chloride contained in the fiber is preferably 1,500 ppm or less.

The meta-type wholly aromatic polyamide fiber of the present invention is a polymer solution for the wet spinning step of the method of the present invention, and the aromatic diamine compound and the chlorinated aromatic compound are used in the solvent of the guanamine compound. The carboxylic acid is polycondensed, and it is obtained by neutralizing the by-produced hydrogen chloride with an alkaline calcium compound, and may contain a meta-type wholly aromatic polyamine, calcium chloride or water.

The meta-type wholly aromatic polyamide fiber of the present invention is preferably a tensile strength of 3.53 cN/dtex (4.0 g/de) or more.

The best form for implementing the invention

The method of the present invention comprises the steps of dissolving in a solvent of a guanamine compound and preparing a polymer solution by using a meta-type wholly aromatic polyamine having a meta-phenylenediamine m-xylyleneamine unit as a main repeating unit. a step of supplying the polymer solution to the wet spinning step and forming the undrawn fiber, the step of stretching the undrawn fiber, the step of washing the obtained drawn fiber, and the step of heat-treating the pre-washed fiber .

The meta-type wholly aromatic polyamine used in the method of the present invention contains a meta-phenylenediamine m-xylyleneamine unit as a main repeating unit, and the production method thereof is not particularly limited, for example, in the form of a meta position. The aromatic diamine component and the chlorinated aromatic dicarboxylic acid component are used as a main raw material, and are produced by solution polymerization or interfacial polymerization.

The meta-type aromatic diamine used for producing the meta-type wholly aromatic polyamine used in the method of the present invention is preferably selected from the diamine compound represented by the following (1).

<chemistry general="n"><img file="TW571007B_D0001.tif" /></chemistry>

In the above formula (1), R represents a halogen atom (e.g., a chlorine atom or a bromine atom), or an alkyl group having 1 to 3 carbon atoms (e.g., methyl or ethyl), and n represents an integer of 0 or 1.

An aromatic diamine of the above formula (1), such as methyl phenylenediamine, 2,4-toluenediamine, 2,6-toluenediamine, 2,4-diaminochlorobenzene, 2, 6-diaminochlorobenzene and the like are preferably selected. As for other meta-type aromatic diamines, 3,4-diaminodiphenyl ether, 3,4-diaminodiphenyl hydrazine, etc. may also be used. .

The meta-type aromatic diamine component used in the present invention is preferably one containing a phenylenediamine or a mixed diamine as a main component. As for the other aromatic diamine used in combination with the meta-phenylenediamine, in addition to the above-mentioned (1) meta-type aromatic diamine (except for the exophenylene diamine), p-phenylenediamine, 2, may also be used. Benzene derivatives such as 5-diaminochlorobenzene, 2,5-diaminobromobenzene, aminomethoxyaniline, 1,5-p-naphthyldiamine, 4,4'-diaminodiphenyl Alkyl ether, 4,4'-diaminobenzophenone, bis(aminophenyl)aniline, bis(p-aminophenyl)methane or the like may also be used.

The polymer used in the method of the present invention preferably has a higher solubility, and the amount of the aromatic diamine other than the phenylenediamine is preferably the total amount of the wholly aromatic diamine component. About 20 mol% or less, preferably for a highly crystalline polymer, for a wholly aromatic diamine component The total amount of molybdenum is preferably 90 mol% or more, more preferably 95 mol% or more.

On the other hand, the chlorinated aromatic dicarboxylic acid component used for producing the meta-type wholly aromatic polyamine used in the method of the present invention preferably contains chlorinated isophthalic acid or a main component thereof. Other chlorinated aromatic dicarboxylic acid obtained by combining chlorinated aromatic dicarboxylic acid component with chlorinated isophthalic acid, for example, chlorinated terephthalic acid, 1,4-naphthalene dicarboxylic acid , 2,6-naphthalene dicarboxylic acid chloride, 4,4'-chlorinated biphenyl dicarboxylic acid, 3-chloroisophthalic acid chloride, 3-methoxyisophthalic acid chloride, and double It is preferred to select (chlorocarbonylphenyl) ether or the like.

In the present invention, in the case where a polymer having good solubility is desired, the total amount of other aromatic dicarboxylic acid to chlorinated aromatic dicarboxylic acid component used in combination with chlorinated isophthalic acid is It is preferable to use an amount of about 20 mol% or less, and a polymer which is highly crystalline, and a total amount of chlorinated aromatic dicarboxylic acid components is used to use a chlorination ratio. More than 90% by mole of phthalic acid is preferred, especially 95% by mole or more.

Among the above-mentioned meta-type wholly aromatic polyamines, 90 to 100 mol% of all repeating unit total amounts are polymers of meta-phenylenediamine m-xylyleneamine units, which are preferably used in the method of the present invention. Preferably, the polymer is substantially free of salts in the polymer.

In the present invention, the above-mentioned meta-type aromatic polyamine solution is a heat-resistant fiber having good mechanical properties, and the adjustment of the degree of polymerization is important irrespective of the content of the inorganic ionic substance. In particular, in terms of a fiber having good performance from a poly(exophenanthroline)-based polymer, the intrinsic viscosity is obtained from a value measured at a polymer concentration of 0.5 g/100 mL in concentrated sulfuric acid at 30 °C ( 1.V.) is 0.8 to 4.0, especially 1.0 to 3.0, of which a polymer of 1.3 to 2.4 is suitable. The degree of polymerization of the polymer is determined by the purpose of the polymer or its solution, the use of the fiber, etc., and the required level can be set. Therefore, if necessary, the degree of polymerization can be controlled by a conventionally known method. One of the representative methods employs a terminal stopper (alkylaniline such as aniline or toluidine, chlorinated benzoic acid, etc.) and can adjust the degree of polymerization.

In the present invention, the meta-type wholly aromatic polyamine is dissolved in a guanamine-based solvent, and it is preferred to supply a polymer solution substantially free of inorganic ionic substances (for example, inorganic salts) to a wet material to be described later. Type spinning step. The polymer solution containing no inorganic ionic substance thus carried out may be obtained by removing a salt from a solvent solution of a guanamine compound containing a meta-type wholly aromatic polyamine obtained by the above-described solution polymerization method or the like. The solution containing the meta-type wholly aromatic polyamine obtained by the solution polymerization, the interfacial polymerization or the like may be used to separate the meta-type wholly aromatic polyamine, and the solvent may be dissolved in the guanamine compound solvent. The fact that the inorganic ionic substance is substantially not contained herein means that the total amount of the inorganic ionic substance in the polymer solution is less than 0.1% by weight, and a very small amount of the salt is acceptable, but the smaller the amount, the better. It is preferably 0 to 0.01% by weight.

In the method of the present invention, the solvent of the guanamine compound used for preparing the polymer solution is preferably N,N-dimethylformamide, N,N-dimethylformamide, N,N-dimethylacetamidine. Amine, N-methyl-2-pyrrolidone, and dimethylimidazolidinone, etc., especially from the solution polymerization to the wet spinning step, the stability of the polymer solution needs to be superior to use N-methyl- 2-pyrrolidone is preferred.

The polymer solution in the wet spinning step of the present invention may contain water. The water contained in the polymer solution may be added as needed, but it may be generated in the solution preparation step. The content of water in the polymer solution is limited to the stable existence of the solution, and is not particularly limited, but it is usually, for example, added or contained in the range of 0 to 60% by weight, particularly 15 parts by weight, based on the weight of the polymer. When the content of water exceeds 60% by weight, the stability of the obtained polymer solution is insufficient, and precipitation of the polymer is formed, gelation occurs, and the spinnability of each of the polymer solutions is significantly impaired. The situation.

As to one embodiment of the method of the present invention, a method for producing a meta-type wholly aromatic polyamide fiber substantially free of inorganic ionic substances will be described below.

<Wet spinning step (1)>

In the method of the present invention, in the wet spinning step, an undrawn fiber obtained from a porous solidified body is formed, followed by a stretching, water washing, and heat treatment step, so as to densify the porous undrawn fiber. The method for producing aromatic amide fiber between the two can produce superior mechanical properties, heat resistance, and substantially no salt by adopting a novel process which has been regarded as impossible as a high efficiency and good productivity. Aromatic amide fiber.

In the foregoing aspect of the method of the present invention, the polymer solution substantially free of the inorganic ionic substance is directly drawn through a porous spinning spinneret having a number of spinning holes of 300 to 3000, to substantially no wire. In the wet spinning step in the salt-containing coagulation bath, by the wet spinning step, it is possible to produce an excellent aromatic melamine fiber system having excellent mechanical properties and heat resistance.

Japanese Laid-Open Patent Publication No. 51-564 discloses a method of performing wet spinning by using a coagulating liquid containing no salt. In this method, a high temperature polyalkylene glycol bath is used as a coagulating liquid, and a coagulating amide fiber can be produced by using a coagulation bath containing no salt. However, since this method uses a non-distillable polymer compound as a coagulation bath, recovery becomes difficult and the cost becomes high. Therefore, this method is not a method suitable for industrial scale manufacturing. Therefore, the spinning method using a salt-free coagulating liquid which is available on an industrial scale, including the recycling system, has not been developed by the developer prior to the present invention.

In order to solve the above problems, in the wet spinning step, a solubilized liquid of a very simple composition of an aqueous solution of a guanamine compound solvent is used to solidify the polymer solution into a homogeneous porous undrawn fiber. That is, in the method of the present invention, after the temperature of the previously described polymer solution is in a temperature range of preferably 20 to 90 ° C, a temperature corresponding to the temperature of the coagulation bath is prepared, and then the above-mentioned spinning spinneret is used. The fiber is drawn to a coagulating liquid having a composition described later at a temperature to form a porous undrawn fiber, and the undrawn fiber is drawn from the coagulating liquid.

In the method of the present invention, the porous undrawn fiber is used in a stretching step, and in the stretching step, the porous undrawn fiber is stretched at a stretching ratio of 2 to 10 times in an aqueous solution of a guanamine compound solvent. . The drawn fiber is subjected to a water washing step and washed with water, and after drying, it is subjected to a heat treatment step at a temperature in the range of 250 to 400 °C. By using the above method of the present invention, it is possible to obtain a dense aromatic melamine fiber which is excellent in physical properties.

As described above, in Japanese Patent Publication No. Sho 52-43930, it is disclosed that a method similar to dry spinning is used, and finally a density of 1.3 g/cm is produced.³A relatively small method of interstitial aromatic amide fibers. However, the wet solidification method of the present invention in the so-called dry spinning method employs a completely technically different method. In this method, in addition to the dry spinning, in the low-temperature solvent-containing aqueous solution, since the step of swelling again is required, the number of the spinning nozzles of the spinning spinneret is increased and the productivity is desired. It is more difficult to make fiber systems. In view of this, in the method of the present invention, by using wet spinning under solidification conditions in a specific temperature range, uniform porous solidification can be formed, which is used for spinning and spinning multi-holes. The board is ready to use. Therefore, in the present invention, the wet spinning step has good productivity, and the formation of the unstretched aromatic amide fiber having a homogeneous porous structure can be achieved.

Further, the inter-porous aromatic amide fiber obtained by the method described in JP-A-52-43930 is designated to have a density of 1.18 g/cm.³Smaller, this prior art blend of aromatic guanamine fibers is a relatively porous fiber compared to the final aromatic amide fibers of the present invention.

In the method of the present invention, in the step after the relatively wet spinning step, in order to achieve a degree of densification which exhibits sufficient physical properties, the pores of the undrawn fibers formed in the solidification stage of the wet spinning step are as possible as possible. It is extremely important to construct a uniform person. The porous structure of the obtained undrawn fiber is closely related to the composition and solidification conditions of the coagulation bath, and therefore the composition of the coagulation bath and the selection of the solidification conditions (for example, temperature) are extremely important.

The coagulation bath used in the wet spinning step of the method of the present invention does not substantially contain an inorganic ionic substance such as a salt, a solvent derived from a guanamine compound, and water (H).₂The O) two component consists essentially of an aqueous solution. The composition of the coagulation bath is limited to the dissolution of the meta-arylene phthalamide polymer, and it is suitably mixed with water, and it can be suitably used, especially by N-methyl-2-pyrrolidone, A solvent selected from the group consisting of methyl acetamide, dimethylformamide, and dimethylimidazolidinone is preferably used. When considering the recovery of a solvent or the like, it is preferred to use the same kind as the guanamine compound solvent contained in the polymer solution.

The proper mixing ratio of the solvent and the water of the guanamine compound contained in the coagulation bath used in the method of the present invention varies depending on the composition and conditions of the polymer solution, but the concentration of the guanamine compound solvent in the coagulation bath is preferably 40~ Within the range of 70% by weight. When the concentration of the guanamine compound solvent is less than 40% by weight, a large amount of the undrawn fiber is likely to be formed, which is a cause of breakage of the subsequent fiber, and if the concentration exceeds 70% by weight, the solidification is carried out. The speed is lowered, and the solidified undrawn fibers are attached to each other.

The appropriate temperature of the coagulation bath varies depending on the composition of the coagulating liquid, but generally, in the case of a relatively high temperature, a coarse bubble-like void called a finger in the solidified undrawn fiber (less) However, in the case where the concentration of the coagulating liquid is high, if the temperature is too high, the unstretched fibers adhere to each other to become easily adhered, so the temperature of the coagulation bath is set to 80 to 90 °C.

The coagulating liquid is preferably composed only of a guanamine compound solvent and water, and it is also possible to add a small amount of a salt even if it is added. In particular, salts such as calcium chloride and calcium hydroxide are extracted from the polymer solution, but the formation of the porous structure is not hindered. For example, when the total weight of the coagulating liquid is 10% by weight or less, preferably 5% by weight or less, more preferably 3% by weight or less, even if it contains a salt, it does not pose a problem. Therefore, the allowable concentration of the salt is in the range of 0 to 10% by weight based on the weight of the coagulating liquid, and the stagnant time of the undrawn fiber in the coagulation bath is preferably 0.1 to 30 seconds. If the stagnation time is too short, the formation of the undrawn fiber becomes insufficient, and the fiber cut phenomenon occurs.

The porous undrawn fiber obtained by the wet spinning step of the method of the present invention is preferably as high as possible, and can be smoothly provided for subsequent densification, so it is preferable, in general, It should be 0.3g~1.0g/cm³Density, preferably 0.5~1.0g/cm³. If the density of undrawn fiber is less than 0.3g/cm³At this time, the porosity is too high. It is difficult to densify this undrawn fiber in the subsequent steps. The density referred to herein is calculated based on the volume and weight of the fiber measured in accordance with ASTM D2130.

In the porous structure of the undrawn fiber obtained by the wet spinning step of the method of the present invention, a very uniform plurality of fine pores are formed, and in the porous structure, a void having a size of several μm or more is referred to as a finger. The large pores are not present, and the micropore size is measured in a submicrom order of 0.1 to 1 μm when measured by a scanning microscope. Such a uniform and fine porous structure, for example due to the spinodal line with solidification The formation of Spinodal decomposition is known. In solidification (wet spinning), by forming a homogeneous microporous structure as described above, it is possible to prevent fiber breakage during stretching, and in the final heat treatment, densification of the fiber structure and practical physical fiber properties are exhibited. It is possible.

In the method of the present invention, a stage in which the polymer is discharged into a coagulation bath, a porous spinneret can be used as the spinneret. Practically, the upper limit of the number of holes per spinneret is about 50,000, and it is preferable to use a spinning spinneret having a number of holes of 300 to 30,000.

<plasticizing stretching step>

In the wet spinning step of the method of the present invention, the porous undrawn fiber obtained by solidification is then introduced into a plasticizable stretching bath formed from an aqueous solution of a guanamine compound solvent, in which the stretching bath is It is stretched at a stretching ratio of 2 to 10 times.

As for the plasticizable stretching bath used in the method of the present invention, an aqueous solution of a guanamine compound solvent can be used. As for the solvent of the guanamine compound, the meta-type wholly aromatic polyamine is swollen, and it is suitable for being mixed well with water, and is preferably used, but N-methyl-2-pyrrolidone or dimethylacetone. One or more kinds of an amine, dimethylformamide, and dimethylimidazolidinone are particularly suitable for use. Further, it is more preferable to use the same solvent as that used in the coagulation bath. If the same solvent as the coagulation bath is used, the recovery step can be simplified and economically beneficial.

That is, the polymer solution, the coagulation bath and the guanamine compound solvent in the plasticizing stretching bath are all used in the same kind, especially for N-methyl-2-pyrrolidone, dimethylacetamide and two. Methylformamide is preferably used singly or as a mixture of two or more of them.

The composition and temperature of the plasticizable stretching bath are closely related, but the concentration of the guanamine compound solvent in the aqueous solution of the guanamine compound is in the range of 20 to 70% by weight, and the temperature of the stretching bath is set to Within the range of 20~90 °C. In the field lower than this range, the plasticization of the undrawn fiber is not sufficiently performed, and it is difficult to stretch it at a sufficient stretching ratio, and if it exceeds these ranges, the undrawn fiber Since the surfaces are dissolved and adhered to each other, it is difficult to obtain a stretched fiber which is good.

The plasticizing stretching step of the method of the present invention is usually 1.5 to 10 times, preferably 2 to 10 times, but it is more preferably stretched at a ratio of 2.1 to 6.0 times. By applying the plasticizable stretching at a high magnification, the strength and the elastic modulus of the obtained inter-aramid amide stretched fiber are improved and exhibiting good physical properties, and the micropores in the undrawn fiber of the porous structure are obtained. It will be subjected to stretching, and the densification caused by the heat treatment step of pre-stretching after plasticizing stretching can be sufficiently performed. However, when the film is stretched at a very high magnification, the process condition is deteriorated, and it is difficult to perform a good stretching.

<Water washing and heat treatment steps>

The drawn fiber of the above-mentioned plasticizable drawn fiber may be washed with cold water of, for example, 30 ° C or lower, and then washed with warm water of 50 to 90 ° C, and then heated by a heated roller, hot air or the like, usually at 100 ° C. The above temperature is dried to remove moisture. Thereafter, dry heat treatment is applied at a temperature of 270 to 400 ° C using a hot plate, a hot roll or the like.

This drying treatment (drying and additional stretching) step is a step in which the pre-stretched porous fiber is densified, and the tensile fiber exhibits practically sufficient strength and elongation. In particular, the temperature of the dry heat treatment (dry heat additional stretching) step is closely related to the density of the heat-treated fiber obtained, and is preferably treated at a temperature of 270 to 400 ° C, more preferably at 300 to 370 ° C. Temperature treatment. When the heat treatment temperature exceeds 400 ° C, the heat-treated fibers obtained are deteriorated drastically, and are colored, which may be destroyed as the case may be. When the heat treatment temperature is lower than 270 ° C, the drawn fiber is not sufficiently densified, and it is difficult to exhibit the desired fiber properties. The dry heat treatment temperature in the heat treatment step of the method of the present invention refers to the set temperature of the heating means such as the hot plate or the heated roll.

In the heat treatment step of the present invention, the stretching ratio used is closely related to the elastic modulus and strength of the obtained drawn fiber, and may be any ratio as necessary, but usually 0.7 to 3 times, especially By setting it in the range of 1.0 to 2.7 times, good hot stretchability and strength, and elasticity coefficient can be obtained. And the draw ratio of 0.7 times here means that the fiber is shrinkage to 70% of the length before the heat treatment by the heat treatment step (shrinkage length: 30%), and the so-called allowable draw ratio is less than 1.0, which means the present invention. The shrinkage amount at the time of heat treatment in the heat treatment step may be limited to a shrink heat treatment within a certain range. The stretching ratio in the heat treatment step is preferably set in consideration of the above-mentioned plasticizing stretching magnification, and the viewpoint of the pre-stretched densification, the expected physical property, and the stable silking property, including plasticity. For the stretching and dry heat stretching, the total stretching ratio is preferably 2.5 to 12 times, more preferably 3.0 to 6 times. The meta-aramid fiber obtained by the present invention is excellent in stretchability, and can be prevented from being broken or fluffed when plasticized stretching or dry heat drawing, and can be smoothly stretched even at a high magnification.

By the above method of the present invention, a tensile aromatic interfacial amide fiber having a tensile strength of 3.53 cN/dtex (4.0 g/de) or more can be obtained.

In other embodiments of the method of the present invention, the polymer solution containing the inorganic ionic substance (inorganic salt) is used as the polymer solution for the wet spinning step. The polymer solution is contained in a solvent of a guanamine compound to condense an aromatic diamine compound and a chlorinated aromatic dicarboxylic acid, and neutralize hydrogen chloride by a basic calcium compound to obtain a meta-type aromatic poly Indoleamine and calcium chloride and water.

The above polymer is produced by the above polymerization method. In the case of the solution polymerization method, as for the solvent, the same guanamine compound (N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-) can be used. Preferably, pyrrolidone, dimethylimidazolidinone or the like is N-methyl-pyrrolidone (NMP).

In the solution polymerization step, usually, the polymerization solvent is preferably NMP, and after the meta-type aromatic diamine component is dissolved in NMP, chlorination with chlorinated isophthalic acid as a main component is added in a powder state or a molten state with sufficient stirring. The aromatic dicarboxylic acid component of the aromatic dicarboxylic acid is reacted. The reaction temperature is 0 to 80 ° C, and the amount of the solvent used is preferably 3 to 30% by weight based on the total amount of the raw materials.

The solution of the meta-type aromatic polyamine thus prepared is neutralized by using a water-soluble basic substance such as calcium hydroxide, sodium hydroxide or sodium hydrogencarbonate because a high concentration of hydrogen chloride is contained. When the reaction is completed, a meta-type aromatic polyamine polymer solution having a preferable degree of polymerization and high chemical stability can be obtained.

The concentration of the polymer in the polymer solution containing the inorganic ionic substance used in the method of the present invention is 100 parts by weight or more based on the total amount of the polymer and the solvent (NMP) (in the present invention, the "PN concentration" is used. In the following description, the value of the unit "weight fraction" of the PN concentration is omitted. The value is preferably 10 to 30, preferably 16 to 30. When the concentration of PN is less than 10, the concentration is too small, and the fiber formation of the solution is deteriorated, and the performance of the fiber is not only reduced, but also the circulation ratio of the solvent (NMP) is high due to the low concentration, and economically, Become unfavorable. Further, the higher the PN concentration, the better the transparency of the molded product (fiber) is. When the PN concentration exceeds 30, the viscosity becomes too high, and there is a problem that the polymerization reaction and the neutralization reaction are not smoothly performed. Therefore, in the case where the polymerization reaction is carried out at a high concentration (for example, a PN concentration of 30 or more), in the neutralization reaction step, if, for example, calcium hydroxide is dispersed in an appropriate amount of NMP (for example, the final PN concentration is 25), In the case of slurry, the neutralization reaction becomes easy, and at the same time, the polymer concentration (PN concentration) in the polymerization system can be adjusted.

The polymer solution contains a meta-type aromatic polyamine and a guanamine compound solvent, and further contains an inorganic ionic substance (salt), and may further contain water. Such water or salt is inevitably formed in the above solution polymerization, and may be added as necessary. Further, in the case of preparing a polymer solution in another solution preparation process, an inorganic ionic substance (salt) and water may be externally added. The inorganic ionic substance (salt) may, for example, be an alkali metal halide such as sodium chloride, sodium iodide or lithium chloride, or an alkaline earth metal halide such as calcium chloride, calcium carbonate, calcium hydroxide or magnesium chloride. Matter, or carbonate, hydroxide, and the like. As for the concentration, any concentration may be used if the solution is in a range in which it can be stably present, and it is usually preferred, for example, to be in the range of 0 or more and 60% or less, particularly preferably 50% or less, based on the weight of the polymer. In the case where the concentration of the inorganic ionic substance exceeds 60% by weight, the inorganic ionic substance in the solution is detrimental to the stability of the polymer solution due to precipitation.

The water content of the above polymer solution is preferably in the range of from 0 to 20%, more preferably from 0 to 15%, based on the total solution. If it exceeds 20% by weight, the stability of the obtained polymer solution may be impaired, and the precipitation of the polymer may cause gelation, and the spinnability may be significantly impaired.

Particularly in the above solution polymerization method, after the polymer is formed, a neutralizing agent is added to the solution and neutralized. As the neutralizing agent used for the neutralization, for example, at least one of calcium oxide, calcium hydroxide, and calcium carbonate is used. By this neutralization reaction, the HCl produced as a by-product of the polymerization is neutralized, and calcium chloride (CaCl) is inevitably formed.₂). The amount of HCl by-product of the polymerization varies depending on the chemical structure of the polymer and the average molecular weight of the smallest unit, but for example, the above-mentioned compound completely neutralizes the polymerization reaction of the poly(m-xylylene phthalamide). In the case of HCl, 100 parts by weight of the polymer, CaCl is formed.₂46.64 (weight) points. At the same time, the CaCl generated by this neutralization reaction₂Is dissolved in the polymer solution, although it has the effect of improving the stability of the polymer solution (see Japanese Patent Publication No. Sho 35-16027), and vice versa due to the large amount of CaCl dissolved.₂In the conventional method, the wet spinning system from the polymer solution is difficult.

On the other hand, the amount of water contained in the neutralization reaction varies depending on the type of the neutralizing agent. When neutralized with calcium hydroxide, the polymer (100 parts by weight) is divided into 15.13 by weight. Divided into water. On the other hand, when calcium oxide or calcium carbonate is used for neutralization, water of 7.56 is formed for 100 parts of the polymer. Moreover, since the neutralizing agent is added as an aqueous solution or a slurry of water and a solvent, it is formed here, and the added water is also dissolved in the polymer solution, but the amount of the above is hardly damaged by the solution. The nature of the composition after safety or neutralization. It is not preferable to say that the water content also has a low viscosity and other characteristics, but if it is quite large, the stability of the solution is remarkably lowered (gelled). Therefore, the appropriate amount of water added in the neutralization reaction step varies depending on the concentration of the polymer, and the amount of water added is 100 minutes for the polymer to be dissolved to about 90 minutes, but the stability of the polymer solution is water pair. The polymer 100 is in the range of 2.42 to 9.7 minutes (water/polymer = 15 to 60% by weight). Further, for example, when the PN concentration is 20, the amount of water added is approximately the same as that of the above PN concentration=16, and the polymer 100 is divided into about 15 to 60 minutes, and the water content of the solution having a PN concentration of 25 is stable. It becomes 15 to 45 minutes, and the PN concentration = 30 is 15 to 30 minutes. The range exemplified above is a rough value when the polymer solution is allowed to stand at 60 to 70 ° C, and there are some variations depending on the polymerization degree of the polymer, the standing storage temperature, and the like. Regardless of how the dissolved permitting concentration of the water of the polymer solution is limited as the concentration of the polymer increases, it is preferred to set the concentration of water in the total polymer solution to 8% in advance when performing the method of the present invention. The following is a standard, and it is necessary to set an appropriate value by experiment, but to prevent gelation of the solution.

Further, if the polymer solution used in the present invention is an aromatic polyamine which can be synthesized from the above-mentioned raw materials, for example, the above-mentioned raw materials are reacted in THF, and an aqueous alkali solution is added, which takes place at the interface between the THF and the aqueous solution. The polymer obtained by neutralizing hydrogen chloride may be dissolved in a solution of a guanamine solvent, or a polymer solution produced by an interfacial polymerization method may also be used.

Always, containing CaCl₂(refers to the calcium chloride formed by the molar polymerization of the indoleamine in the solution polymerization method). The meta-type aromatic amide polymer solution is intended to be wet-drawn by wet spinning. The fiberization system is difficult, so it has been used as a method of spinning, and can be used as a dry spinning method or a semi-dry and semi-wet spinning method. Since this is used for the wet spinning method, any one of the solution polymerization method and the interfacial polymerization method may also at least neutralize the chloride salt (CaCl) formed by the by-produced HCl by any means.₂, NaCl, NH₄Cl or the like is reduced to less than 70% of the amount produced. It is preferably 20% or less, and it is necessary to prepare a salt-reducing polymer. However, the removal of chloride by such means is often difficult on an industrial scale, for example, in the case of interfacial polymerization of a synthetic polymer, the polymerization solvent and the solvent for spinning are caused by different types thereof, and the like. In the case of recovery, a separate recovery device is required, or a polymer solution synthesized by solution polymerization is prepared by using the same solvent as the polymerization solvent. In the case of spinning this, the neutralization by-product can also be removed by pressure filtration. Inorganic chloride (due to the high viscosity of the industrial manufacturing system is extremely difficult), or after adding water to the polymer solution and washing with water to remove the inorganic chloride, it is difficult to dry the polymer and redissolve, etc. Problems such as high energy costs and high environmental pollution.

According to the method of the present invention, even such a molar containing CaCl which is relatively difficult to implement has been used.₂The polymer solution can be produced by a spinning spinneret by direct spinning to a wet spinning step in a coagulation bath having a specific composition substantially free of salts, thereby producing gloss, mechanical properties and heat resistance. The meta-type aromatic amide fiber.

In the wet spinning step of the method of the present invention, a solid solution of a so-called guanamine compound solvent is used to solidify the polymer solution to obtain a homogeneous porous undrawn fiber. That is, in the present invention, the temperature of the previously described polymer solution is preferably in the range of 20 to 90 ° C, adjusted to a temperature corresponding to the temperature of the coagulating liquid used, and directly extracted by a spinning spinneret ( Filament) to the above-mentioned composition, in a coagulation bath at a temperature, after forming a porous undrawn fiber, the undrawn fiber is pulled out from the coagulating liquid, and then in an aqueous solution of a guanamine compound solvent (preferably 2 times or more) 10 times or less of the stretching ratio), washed with water, dried, and further heat treated.

The homogenous and porous undrawn fiber obtained by the wet spinning step from the polymer solution containing the inorganic ionic substance is subjected to the same plasticizing stretching, water washing and heat treatment steps as described above. A homogeneous and dense meta-type wholly aromatic polyamide fiber can be obtained with higher efficiency and higher productivity.

By the above method of the present invention, a tensile aromatic interfacial amide fiber having a tensile strength of 3,53 cN/dtex (4.0 g/de) or more can be obtained.

In the method of the present invention, the so-called wet spinning step, the plasticizing stretching step, the cleaning step, and the continuous and consistent step of the drying heat treatment step are carried out, which is also one of the advantages of the present invention, but is divided into Several steps can be implemented by replacing the order.

Further, the fibers produced in this manner may be subjected to crimping as necessary, and/or may be cut to an appropriate fiber length to provide a textile or other processing step.

<Fiber obtained by the present invention>

The meta-type wholly aromatic polyamine (meta-indolylamine) fiber obtained by the method of the present invention has the same dense structure as the usual inter-aramid fiber, and has a fiber density of 1.2 g/cm.³Above, preferably 1.3g/cm³In the following, the fiber content is excellent, and the content of the salt in the fiber can be reduced as much as possible, and the total content of the inorganic ionic substance in the fiber can be controlled to be 500 ppm or less, preferably 300 ppm or less. Therefore, in a preferred form, the calcium concentration in the fiber which is adversely affected by the physical properties of the fiber or the heat resistance and the post-processability can be controlled to 0 to 100 ppm. Further, the concentration of the chloride in the fiber which has a bad influence on the electrical properties such as electrical insulation can be controlled to 0 to 150 ppm.

<Use of fiber>

The meta-type wholly aromatic polyamine (m-arylamine) fiber obtained by the method of the invention has excellent heat resistance, flame resistance and mechanical properties, and can be applied to various uses utilizing such properties, in particular More suitable for use in the mixing of aversive ionic substances. For example, alone or in combination with other fibers, woven into a woven fabric, used for fire-resistant clothing, protective clothing and other heat-resistant flame-retardant materials, flame-resistant bedding, internal decoration materials, especially non-woven fabrics can be used for filters, etc. Industrial materials, or materials that can be effectively used as raw materials for synthetic papers and composite materials, and suitable for controlling the content of ionic substances, such as woven fabrics, non-woven fabrics, synthetic papers, etc., are also particularly effective for electrical insulating materials and electronic equipment. Components, printed circuit boards and other fields.

Example

The invention will be described in more detail by way of the following examples and comparative examples. However, the examples and comparative examples are intended to be illustrative of the present invention, and the scope of the invention is not limited by the description.

Further, in the following Example 1 and Comparative Example 1, the polymer has a viscosity (IV), and the polymer solution obtained in the polymerization step is separated from the aromatic polyamide polymer and dried. In sulfuric acid, concentrated in polymer Degree 100mg/100<img file="TW571007B_D0002.tif" />The value of sulfuric acid measured at 30 °C. Further, the polymer concentration (PN concentration) of the polymer solution (spinning stock solution) used for spinning is the % by weight of the polymer to the total weight of the polymer solution, that is, {polymer weight / (polymer) Solution weight)} × 100 (%).

Further, the density of the porous undrawn fiber obtained by the coagulation step was calculated from the diameter and the fineness value (dtex value) of the fiber measured in accordance with ASTM D2130. Further, the density of the heat-treated fibers was measured by a floatation method using a mixture of tetrachloroethane and cyclohexane as a solvent.

The concentration of the metal in the obtained fiber is determined by atomic absorption for the alkali metal and ICP for other metal ions. Further, the concentration of the inorganic chloride in the fiber was quantified by Dozmann micro-coulometric titration.

Example 1

(a) Preparation of polymer solution

The interfacial polymerization method described in Japanese Patent Publication No. Sho 47-10863 is produced by the following procedure.

Dissolving chlorinated isophthalic acid and meta-phenylenediamine in an equal amount in tetrahydrofuran (THF), contacting the solution with aqueous sodium carbonate solution and interfacial polymerization, and washing to obtain poly(m-phenylene phthalamide) powder. The poly(m-phenylene phthalamide) has an intrinsic viscosity of 1.9. 21.5 parts by weight of m-xylguanamine powder was suspended in 78.5 parts by weight of N-methyl-2-pyrrolidone which had been cooled to 0 ° C to prepare a slurry, and the slurry was heated to 60 ° C to prepare a transparent polymer. Solution.

The concentration of the inorganic ions in the above polymer powder was Na: 730 ppm, K: 8.8 ppm, Ca: 5 ppm, and Fe: 2.3 ppm. Further, the polymer concentration in the above polymer solution was 21.5%.

(b) Wet spinning step

The polymer solution prepared by the above step (a) is a spinning dope, and is discharged from a spinning spinneret having a pore diameter of 0.05 mm and a pore number of 50 to a coagulation bath having a bath temperature of 80 ° C, and is solidified and formed into a non-stretched state. Stretch the fiber. This coagulation bath had a composition of water/NMP = 45/55, a dipping length (effective coagulation bath length) of 60 cm, and a fiber walking speed of 8 m/min. The undrawn fiber is temporarily pulled from the coagulation bath into the air.

Unstretched fibrous porous body having a density of 0.65 g/cm³。

(c) plasticizing stretching step ~ drying hot stretching step

The undrawn fiber was introduced into a plasticizable stretching bath, and this was stretched at a stretching ratio of 3 times. The plasticizable stretching bath at this time had a composition of water/NMP = 70/30, and the temperature was 80 °C. After the stretching step, the drawn fiber was introduced into a water washing step, sufficiently washed with water of cold water, and further washed with warm water of 80 °C. Then, the water is given to the water. The washed drawn fiber is stirred on the peripheral surface of the drying roller having a surface temperature of 120 ° C and dried, and the obtained stretched and dried fiber is dry-drawn to 1.2 times and heated in a hot plate at 340 to 360 ° C. The obtained heat-treated fiber is taken up by winding. The total draw ratio in the present example was 3.6 times, and the final take-up speed of the drawn fiber was 28.8 m/min.

(d) Fiber properties

When measuring the mechanical properties of the obtained poly-m-phenylene phthalamide fiber, the fineness is 1.89 dtex (1.7 de), and the density is 1.3 g/cm.³The tensile strength is 3.11 cN/dtex (3.52 g/de), the elongation is 24.5%, and the Young's coefficient is 69.2 g/de (61.1 cN/dtex), and the mechanical properties are good.

The ion concentration of the obtained fiber showed an extremely low content as described in Table 1 below.

<tables><img file="TW571007B_D0003.tif" /></tables>

Comparative example 1

For comparison, the commercially available poly(phenylene phthalamide) fiber (Temperature "Cornex" ion concentration is shown in Table 2.

<tables><img file="TW571007B_D0004.tif" /></tables>

Further, in the following Examples 2 and 3, the intrinsic viscosity (IV) was The aromatic polyamine polymer is separated from the polymer solution and dried, and the polyamine polymer is dissolved in concentrated sulfuric acid to a polymer concentration of 0.5 g/100.<img file="TW571007B_D0005.tif" />, the value measured at 30 ° C. Furthermore, the polymer concentration (PN concentration) of the polymer solution used in the spinning step is the weight of the polymer to the total weight of the polymer solution [= polymer / (polymer solution)%], calcium chloride and water The concentrations are each a weight fraction of 100 parts by weight of the polymer.

The density of the porous linear body obtained by solidification is the density of the apparent density tensile heat-treated fiber calculated from the diameter and the fineness (dtex) of the fiber measured by ASTM D2130, using tetrachloroethane and The mixture of cyclohexane is a value measured by a floatation method of a solvent.

Example 2

(a) using a solution polymer to prepare a polymer solution, and in a reaction vessel equipped with a preparation thermometer, a stirring device, and a raw material input port, a NM815 fraction dehydrated by using a molecular sieve is added, and the phenylenediamine is dissolved in the NMP ( Hereinafter, referred to as mPDA) 108 minutes, it was cooled to 0 °C. In the cooled diamine solution, 2-3 parts of chlorinated isophthalic acid (hereinafter abbreviated as IPC) which was purified by distillation and pre-pulverized in a nitrogen atmosphere was added and stirred for stirring. The reaction temperature was raised to about 50 °C. Stirring was continued at this temperature for 60 minutes, then warmed to 60 ° C and allowed to react for 60 minutes. After the reaction, 70 parts of calcium hydroxide was added to the reaction vessel as a fine powder, and the polymer solution was neutralized and dissolved for 60 minutes. Secondary and). Further, a slurry in which calcium hydroxide 4 is dispersed in NMP 83 minutes is prepared, and the calcium hydroxide-containing slurry (neutralizer) is stirred in the previously neutralized polymer solution, and simultaneously added ( Secondary neutralization). This secondary neutralization system was stirred at 40 to 60 ° C for about 60 minutes and was carried out. The neutralized polymer solution was prepared by completely dissolving in calcium hydroxide.

The polymer concentration (PN concentration, that is, the weight of the polymer to 100 parts by weight of the polymer and NMP) of the polymer solution (stranded stock solution) is 14, and the resulting poly-m-phenylene phthalate The amine polymer has an IV of 2.4. Further, the calcium chloride concentration and the water concentration of the polymer solution were divided into 46.6 parts of calcium chloride and 15.1 parts by weight of the polymer.

(b) Wet spinning, plasticizing stretching, water washing, drying and hot drawing steps

The above-mentioned spinning stock solution (a) was discharged through a spinneret having a pore diameter of 0.09 mm and a number of pores of 50 to a coagulation bath having a bath temperature of 80 ° C to form an undrawn fiber. This coagulation bath had a composition of water/NMP = 50/50 (weight ratio), a dipping length (effective coagulation bath length) of 60 cm, and an unstretched fiber running speed of 8 m/min. The solidified undrawn fiber is temporarily pulled into the air. The density of the porous undrawn fiber drawn from the coagulation bath was 0.74. This undrawn fiber is then introduced into a plasticizable stretching bath and subjected to a stretching step of 3 times the draw ratio. The plasticizable stretching bath at this time had a composition of water/NMP = 45/55 (weight ratio) and a temperature of 40 °C. The drawn fiber is subjected to washing with water, and then at 80 ° C. Warm water wash. Next, the pre-washed drawn fiber was dried on a drying roll having a surface temperature of 120 ° C, and stretched at 1.2 times dry heat on a hot plate at 340 to 360 ° C, and pre-wound. The total draw ratio of this example was 3.6 times, and the final take-up speed of the drawn fiber was 28.8 m/min.

When the mechanical properties of the obtained poly(m-phenylene phthalamide) drawn fiber were measured, the fineness was 1.89 dtex (1.7 de), the density was 1.33, the tensile strength was 3.62 cN/dtex (4.1 g/de), and the elongation was 38%. The Young's coefficient is 86.5 cN/dtex (98 g/de), and the mechanical properties are good.

Example 3

The same polymer solution as in Example 2 was used and subjected to spinning. This polymer solution was discharged through a spinneret having a pore size of 0.09 mm and a number of pores of 500 to a coagulation bath having a bath temperature of 80 ° C to form a porous undrawn fiber. In this case, the coagulation bath has a composition of water/NMP=45/55, and the plasticizable stretching bath is composed of a small/NMP45/55 composition. In the coagulation bath, the undrawn fiber had a dipping length of 50 cm, and the undrawn fiber had a running speed of 8 m/min. The plasticized drawn fiber, the water washing step, the drying step, and the dry heat stretching step were carried out in the same manner as in Example 1. The inter-phenylene phthalamide fiber can be obtained. The density of the porous undrawn fiber obtained from the coagulation bath was 0.82. When the physical properties of the obtained tensile heat-treated fiber were measured, the fineness was 2.11 dtex (1.9 de), the density was 1.32, the tensile strength was 3.71 cN/dtex (4.2 g/de), the elongation was 21%, and the Young's modulus was 84.7 cN/dtex (96 g). /de), showing good mechanical properties.

According to the method of the present invention, the mechanical properties, the heat resistance and the like are good, and the dense meta-type wholly aromatic polyamide fibers (especially polyphenylene benzene) which are substantially free or contain salts can be produced with high productivity. Meta-xylyleneamine fiber). A meta-type wholly aromatic polyamide fiber which does not substantially contain an inorganic ionic substance, that is, an extremely low concentration of an inorganic ionic substance, and is a meta-type wholly aromatic which is heat-resistant, flame-resistant, and electrically insulating. The inherent properties of the polyamide fibers are also excellent in electrical properties and the like, and are particularly useful as materials for electronic equipment.

Further, according to the method of the present invention, it can be produced by a solution polymerization method, and the inorganic ionic substance is not separated from the poly-polyamine polymer solution containing the neutralizing salt, and can be directly discharged to the solvent and water by the guanamine compound. In the obtained coagulation bath, by the step of solidifying into a porous undrawn fiber, it has excellent mechanical properties, and by virtue of good productivity, a meta-type having good heat resistance and flame resistance can be produced. Amidamide fiber.