KR940000963B1 - Production process for polyimide fibers - Google Patents

Abstract

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Description

Manufacturing method of polyimide fiber

1 is a diagram showing thermal parallax characteristics by DSC of polyimide resin used in the present invention.

The present invention relates to a method for producing a polyimide fiber which is excellent in heat resistance, chemical resistance, radiation resistance and mechanical strength and excellent in productivity.

The aromatic polyimide fibers conventionally obtained by melt spinning by direct heating have been disclosed by the applicant in Japanese Patent Application Laid-Open No. 63-211319. In other words, this publication discloses a high-strength and high sheet-like polyimide fiber composed of novel polyimide capable of melt spinning and having good processability. However, the polyimide fiber has a decrease in discharge amount due to thickening of the melt index or clogging of the filter during continuous spinning for a long time, and a large number of thread cuts at the time of spinning and stretching, resulting in increased fiber productivity. It was not yet satisfactory.

In addition, the present inventors have invented the following method for producing a polyimide, and the applicant has filed a patent application with the Japanese Patent Office (Japanese Patent Application No. 62-266191). The production method is a method of reacting a specific diamine with a specific tetracarboxylic dianhydride in the presence of a specific dicarboxylic anhydride. According to this method, the terminal of the high molecular chain is dicarboxylic acid anhydride. A sealed polyimide is obtained. Preliminarily drying this polyimide and adjusting the water content to less than 200ppm, preferably less than 50ppm, the fluidity does not decrease much even when exposed to high temperature for a long time, so that it is suitable for melt molding such as injection molding and extrusion molding. It is a resin material excellent in molding processability.

The object of the present invention can be produced by stable spinning and stretching for a long time without losing the heat resistance, chemical resistance and mechanical strength of the aromatic polyimide described in Japanese Patent Application Laid-Open No. 63-211319. The present invention provides a method for producing a high strength polyimide fiber free of foaming, coloring, and gelling during spinning and stretching.

Further, another object of the present invention is to provide a novel use for the method for producing a polyimide of the same special element 62-266191.

The object is achieved by providing the following method.

In the method for producing a polyimide fiber comprising thermally or chemically imidating a polyimide acid obtained by reacting a diamine with a tetracarboxylic dianhydride and spinning the polyimide after oxidation of the polyamic acid or its imide,

(A) Diamine is represented by the following formula (I)

(Wherein X represents a group selected from the group consisting of a straight chain, a divalent hydrocarbon group having 1 to 10 carbon atoms, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, or a sulfonyl group), and

(B) Tetracarboxylic dianhydride is represented by the following formula (II)

(Wherein R represents a tetravalent group selected from the group consisting of aliphatic groups having 2 or more carbon atoms, cyclic aliphatic groups, monocyclic aromatic groups, condensed polyaromatic aromatic groups, or non-condensed polyaromatic aromatic groups interconnected by a crosslinking member) box.)

Including tetracarboxylic dianhydride represented by,

(C) The reaction is also represented by the following formula (III)

(Wherein z represents a divalent group selected from the group consisting of monocyclic aromatic groups, condensed polyaromatic groups, and non-condensed polyaromatic groups in which aromatic groups are directly or interconnected by a bridging member.)

In the presence of dicarboxylic acid anhydride represented by

(D) The amount of tetracarboxylic dianhydride used is 0.9 to 1.0 mole ratio per 1 mole of diamine used, and the amount of dicarboxylic acid anhydride is 0.001 to 1.0 mole ratio per 1 mole of diamine used.

Formula (Ⅳ)

(Wherein X and R are as defined above).

Method for producing a polyimide fiber having a repeating unit represented by the basic skeleton.

It yl-As expression (Ⅰ) in the X of the diamine used in the preparation of the polyimide used in the present invention, for example, a direct connection, -S-, -C (CH3) 2- , -CO- or -SO ₂ desirable. Specific examples of the polyamine include bis [4- (3-aminophenoxy) phenyl] pentane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 2,2-bis [4- (3 -Aminophenoxy) phenyl] propane, 2- [4- (3-aminophenoxy) phenyl-2- [4- (3-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (3-aminophenoxy) -3-methylphenyl] propane, 2- [4- (3-aminophenoxy) phenyl-2- [4- (3-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (3-aminophenoxy), 3,5-dimethylphenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [ 4- (3-aminophenoxy) phenyl-1,1,1,3,3,3-hexafluoropropane, 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (3 -Aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, and the like. It is used by mixing above.

In addition, in the range which does not lose the favorable physical property of the polyimide used by this invention, using one part of the said diamine by using another diamine does not interfere at all. When replacing, the molar ratio range of another diamine is preferably 1.0-50.0 mol%.

As a diamine which can be used by replacing partially, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, bis (3-aminophenyl) ether, for example. , (3-aminophenyl) (4-aminophenyl) ether, bis (4-aminophenyl) ether, bis (3-aminophenyl) sulfide, (3-aminophenyl (4-aminophenyl) sulfide, bis ( 4-aminophenyl) sulfide, bis (3-aminophenyl) sulfoxide (3-aminophenyl) (4-aminophenyl) sulfoxide, bis (4-aminophenyl) sulfoxide, bis (3-aminophenyl) sulfone , (3-aminophenyl) (4-aminophenyl) sulfone), bis (4-aminophenyl) sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'- Diaminobenzophenone, bis [4- (4-aminophenoxy) phenyl] methane, 1,1'-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4 -Aminophenoxy) phenyl] ethane, 2,2-bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (4-aminophenoxy) Phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3 , 3, -hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene , 1,4-bis (3-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl) sulfone, bis [4- (3- Aminophenoxy) phenyl) ether, bis4- (4-aminophenoxy) phenyl) ether, 1,4-bis [-(3aminophenoxy) benzoyl] benzene, 1,3- [4- (3-amino Phenoxy) benzoyl] benzene, etc. are mentioned.

Moreover, R in Formula (II) of tetracarboxylic dianhydride used for manufacture of the polyimide used by this invention,

또는For example,

or

등이 바람직하다.

Etc. are preferable.

Specific examples of the tetracarboxylic dianhydride include ethylene tetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, pyromellitic dianhydride, 1,1-bis (2,3 dicarboxyphenyl) ethane dianhydride, Bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2- Bis (2,3-dicarboxyphenyl) propane dianhydride, dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride , 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3'4,4'-benzophenonetetracarboxylic acid dianhydride , 2,2 ', 3,3'-benzophenonetetracarboxylic dianhydride, 3,3'4,4'-biphenyltetracarboxylic dianhydride, 2,2 ", 3,3'-biphenyltetracarboxylic dianhydride , Bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicar Carboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 4,4 '-(p-phenylenedioxy) diphthalic acid dianhydride, 4,4'-(m-phenylenedioxy) Diphthalic anhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8, -naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1, 2,3,4-benzenetetracarboxylic acid dianhydride, 3,4,9,10-phenylenetetracarboxylic dianhydride, 2,3,6,7-anthracentracarboxylic dianhydride, 1,2,7,8- It is phenanthrene tetracarboxylic dianhydride etc., These tetracarboxylic dianhydrides are used individually or in mixture of 2 or more types.

Moreover, as dicarboxylic acid anhydride [formula (III)] used for manufacture of the polyimide used by this invention, phthalic anhydride, a biphenyl dicarboxylic acid anhydride, and benzophenone dicarboxylic acid anhydride are preferable, for example.

As a specific example, phthalic anhydride, 2, 3- benzophenone dicarboxylic acid anhydride, 3, 4- benzophenone dicarboxylic acid anhydride, 2, 3- dicarboxy phenyl ether anhydride, 3, 4- dicarboxy phenyl ether anhydride, 2, 3- Biphenyl dicarboxylic acid anhydride, 3,4-biphenyl dicarboxylic acid anhydride, 2,3-dicarboxyphenylsulphenyl sulfone anhydride 3,4-dicarboxyphenyl sulfone anhydride, 2,3-dicarboxyphenyl sulfide anhydride, 3, 4-dicarboxyphenyl sulfide anhydride, 1,2-naphthalenedicarboxylic acid anhydride, 2,3-naphthalenedicarboxylic acid anhydride, 1,8-naphthalenedicarboxylic acid anhydride, 1,2-anthracenedicarboxylic acid anhydride, 2,3-anthracene Dicarboxylic acid anhydride, 1.9- anthracene dicarboxylic acid anhydride, etc. are mentioned, These are used individually or in mixture of 2 or more types.

The molar ratio of the amine, tetracarboxylic dianhydride and dicarboxylic dianhydride used in the production of the polyimide used in the present invention, per mole of diamine, 0.9 to 1.0 mole of tetracarboxylic dianhydride, 0.001-1.0 to dicarboxylic acid anhydride It's a mole.

In preparation of polyimide, in order to adjust the molecular weight of the produced polyimide, adjusting the ratio of the diamine and tetracarboxylic dianhydride is normally performed. In the method of the present invention, in order to obtain a polyimide having good melt fluidity, the molar ratio of tetracarboxylic dianhydride to diamine is from 0.9 to 1.0.

Moreover, the amount of 0.001-1.0 molar ratio with respect to diamine is used for the dicarboxylic acid anhydride to coexist. If it is less than 0.001 molar ratio, it cannot aim at the stable spinning and extending | stretching aimed at by this invention. Moreover, when more than 1.0 molar ratio, mechanical property will fall. Preferable usage amount is 0.01-0.5 molar ratio.

Although the polyimide used by this invention may be made to react by what kind of method, if it uses the reactive component mentioned above, it is a preferable method to make it react in an organic solvent.

Examples of the organic solvent used in the reaction include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, and N-methyl. 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis ( 2-methoxyethoxy) ethane, bis (2- (2-methoxyethoxy) ethyl} ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioic acid, pyridine, picoline, dimethylsulfoxide Seed, dimethyl sulfone, tetramethyl urea, hexamethylphospholamide, phenol, m-cresol, p-cresol, p-chlorophenol, anisole, etc. These organic solvents may be used alone or in combination of two or more. You can mix and use.

In the production of the polyimide used by the method of the present invention, as a method of adding and reacting diamine, tetracarboxylic dianhydride and dicarmoxic anhydride as starting materials to the organic solvent, (A) diamine and tetracarboxylic acid 2 An anhydride is made to react, the dicarboxylic acid anhydride is continued, and the reaction is continued, (b) The dicarboxylic acid anhydride is added and reacted to dianmine, the tetracarboxylic dianhydride is added continuously, and the reaction is continued further, (C) Any addition or reaction may be performed, such as a method of simultaneously adding and reacting diamine, tetracarboxylic dianhydride and dicarboxylic anhydride.

The reaction temperature is usually performed at a temperature of 60 ° C or lower at 0 ° C to 250 ° C.

The reaction pressure is not particularly limited and can be sufficiently performed at normal pressure.

Although reaction time changes with diamine, tetracarboxylic dianhydride, dicarboxylic anhydride, the kind of solvent, and reaction temperature to be used, it is sufficient for 4 to 24 hours normally.

By this reaction, a polyamic acid having a repeating unit of the following formula (V) as a basic skeleton is produced.

(Wherein X and R are as defined above).

Based on the repeating unit of the following formula (IV) by chemically imidating the polyamic acid by heating and dehydrating it at 100 to 400 ° C or by using a commonly used imidating agent such as triethylamine and acetic anhydride. The corresponding polyimide which has as a skeleton is obtained.

(Wherein X and R are as defined above).

In general, after the polyamic acid is produced at a low temperature, it is further thermally or chemically imidized. However, polyimide can also be obtained by simultaneously producing the polyamic acid and thermal imidization reaction at a temperature of 60 ° C to 250 ° C. That is, diamine, tetracarboxylic dianhydride and aromatic dicarboxylic acid anhydride are suspended or dissolved in an organic solvent and then reacted to heat, followed by simultaneous production of polyamic acid and dehydration, and the basic unit of formula (IV) as the base. Polyimide which has as a skeleton can also be obtained.

The polyimide obtained in this way is a thermoplastic resin which can be melt-molded and, on the other hand, illustrates the typical thermal parallax characteristic in FIG. The curve ① is an example in the case of displaying crystallinity, and the curve ② is an example in the case of not displaying crystallinity. Tg is the glass transition temperature, Tc is the crystallization temperature, and Tm is the melting temperature. Although Tg of this polyimide has a slight difference according to the combination of each component of tetracarboxylic dianhydride, diamine, and dicarboxylic acid anhydride, it shows about 180-265 degreeC, and Tc is about 290-330 degreeC, or In some cases, Tc is not displayed. Tm may not show about 365-395 degreeC or Tm. In the case of fibrosis, it is preferable to perform melt spinning by direct heating. However, as disclosed in Japanese Patent Laid-Open No. 63-211319, a poly represented by the above formula (V) which is a precursor of polyimide Polyamic acid fibers are produced by wet spinning a solution in which amic acid is dissolved in a fat or oil solvent in a coagulation bath, followed by imidization by work or chemical treatment, to obtain polyimide fibers similar to melt spinning.

In the case of melt spinning, the polyimide of the present invention is sufficiently preliminarily dried, the amount of water contained is adjusted to less than 200 ppm, preferably less than 50 ppm, and then, e.g. In the temperature range of Tm + 5) ° C to (Tm + 100) ° C, preferably (Tm + 10) ° C to (Tm + 50) ° C, the crystallinity shown in FIG. 1 is not displayed. The extruder of the screw type or plunger type is melted in the heating barrel within a temperature range of (Tg + 50) ° C to (Tg + 180) ° C, preferably (Tg + 80) ° C to (Tg + 140) ° C. It is then discharged in the form of monofilament or multifilament from the nozzle at the tip of the extruder, and pulled and spun while cooling and solidifying. It is also possible to insert the front of the nozzle for the purpose of removing foreign matter or gel. The unstretched emitting yarn thus obtained is, for example, (Tg-50) ° C to Tm ° C, preferably (Tg-30) ° C to Tc ° C when displaying the crystallinity shown in FIG. On the other hand, in the case where the crystallinity shown in FIG. 1 is not displayed, (Tg-50) ° C to (Tg + 50) ° C, and preferably (Tg-30) ° C to (Tg + 30) ° C. In the temperature range, 1.01 to 5 times hot stretching is performed in one or multiple stages. Stretching can use the conventionally well-known apparatus by the contact system of a heating furnace type non-contact system, a hotplate contact system, and a heating nozzle passing type | mold.

The stretched yarn obtained in this way is Tg ° C to Tm ° C, preferably (Tg +) in the case of showing ① crystallinity shown in FIG. In the range of 30) ° C to (Tm-30) ° C, on the other hand, when the crystallinity shown in FIG. 1 is not displayed, (Tg-30) ° C to (Tg + 30) ° C, preferably (Tg Heat treatment is performed in the temperature range of -20) ° C to Tg ° C to prevent post-shrinkage of the polyimide fiber.

According to the method for producing a polyimide fiber of the present invention, when spinning and stretching, it is accompanied by a thickening phenomenon or a gel formation phase which is thought to be due to the binding of the polymer chain terminal, and decomposition gas generation which is considered to be due to thermal decomposition of the terminal. It is possible to prevent foaming and coloring from being formed, thereby eliminating thread cutting, and stably perform long-term continuous spinning and stretching.

The polyimide fiber of the present invention is useful as an industrial fiber over a wide range of single filament from a multi-filament of several denier to a monofilament of about 1 mm in diameter, and has heat resistance, chemical resistance, radiation resistance and It is excellent in mechanical strength, and can be manufactured stably and borderlessly.

Example 1

Into a reaction vessel equipped with a stirrer, a reflux condenser and a nitrogen introduction tube, 368 g (1.0 mol) of 4,4'-bis (3-aminophenoxy) biphenyl and 5215 g of N, N-dimethylacetamide were charged, and the room temperature was charged. Under nitrogen atmosphere, 211,46 g (0.97 mol) of pyromellitic anhydride was added while dividing around the rise of solution temperature, and it stirred at room temperature for about 20 hours.

22,2 g (0.15 mol) of phthalic anhydride was added to this polyamic-acid solution at room temperature under nitrogen atmosphere, and it stirred for further 1 hour. Subsequently, 404 g (4 mol) triethyleneamine and 306 g (3 mol) acetic anhydride were dripped at this solution. After completion of dropping, yellowish polyimide powder began to precipitate within about 1 hour. The mixture was stirred at room temperature for 10 hours and filtered. The mixture was washed with methanol, filtered, dried at 180 ° C. for 2 hours, and 536 g of polyimide powder was obtained. This polyimide showed crystallinity, and the glass transition temperature Tg shown in FIG. 1 was 256 ° C, the melting temperature Tm was 378 ° C, and the crystallization temperature Tc was 306 ° C, and the logarithmic viscosity of this polyimide powder was 0.53. dl / g. Here, the logarithmic viscosity is a value measured at 35 ° C. with a concentration of 0.5 g / 100 ml solvent using a mixed solvent of parachlorophenol: phenol (weight ratio 90:10).

In the screw-type extruder (screw diameter 25mm, L / D = 24, with a forced vacuum bend) with the heating tube which set the obtained polyimide powder at 400 degreeC, one round hole of diameter 3mm is extruded from a nozzle. And polyimide pellets having a diameter of 2 mm and a length of 3 mm were obtained by air cooling. In addition, during operation, the vacuum degree of the forced vent was 10 Torr. Next, a round hole with a diameter of 0.8 mm in a screw-type extruder (screw diameter 10 mm, L / D = 20, no-vent type, 10 μm filter in front of the nozzle) with a heating tube set to 400 ° C. The extrusion speed was uniformly extruded from the nozzle having the nozzle, and the rate of ejection of spinning was adjusted to obtain polyimide yarn A having a diameter of 300 µm and polyimide single yarn B having a diameter of 100 µm at air cooling.

Although the above operation was continued for 10 hours, it was possible to stably radiate without interruption in the middle.

In addition, the indication of the pressure gauge for resin provided in front of the filter was 40 kg / cm 2, 55 kg / cm 2 after 10 hours, and the clogging of the filter was only a little. The obtained polyimide yarns of 300 µm and 100 µm in diameter were drawn in a heating furnace set at 240 ° C. at a draw ratio of 2.5 and a draw rate of 60 times / minute (stretched at a length of 60 times in one minute), followed by stretching. Al and Bl were obtained, respectively.

Next, Al and Bl were heat-treated in tension without heat for 30 minutes at a heating rate set to 300 ° C to obtain heat-treated stretched yarns A2 and B2.

Similarly, the same stretching treatment was performed in a heating furnace set at 280 ° C to obtain stretched yarns A3 and B3. Then, the same heat treatment was performed under 300 degreeC, and heat processing stretched yarn A4 and B4 were obtained.

The results of measurements of tensile strength and tensile extension (JIS-L-1813 (1981)) of the obtained polyimide fibers are shown in the first table.

Example 2

In the same reaction vessel as in Example 1, 400 g (1.0 mol) of bis [4- (3-aminophenoxy) -phenyl] sulfide and 5503 g of N, N-dimethylacetate amide were charged and under a nitrogen atmosphere in Ceylon. 211.46 g (0.97 mol) of pyromellitic dianhydride (PMDA) was added, being careful about raising solution temperature, and it stirred at room temperature for about 20 hours.

To this polyimide acid solution, 22.2 g (0.15 mol) of phthalic anhydride was added under a nitrogen atmosphere in Ceylon, followed by further stirring for 1 hour. Subsequently, 404 g (4 mol0 of triethylamine and 306 g (3 mol) of acetic anhydride were dripped at this solution. After stirring was continued for about 10 hours after completion | finish of dripping, it discharged in about 10 kg of methanol, and filtered. Methanol dispersion and filtration were followed by filtration and drying under reduced pressure at 180 ° C. for 6 hours to obtain 570 g of polyimide powder, which showed no crystallinity and the glass transition temperature Tg shown in FIG. The logarithmic viscosity according to the logarithmic viscosity measurement method shown at 208 ° C and Example 1 was 0.47 dl / g.

The polyimide powder thus obtained was obtained in the same manner as in Example 1 to obtain a polyimide pellet under the condition of a heating tube temperature of 360 ° C., and then to obtain a polyimide single yarn E having a diameter of 250 μm. During the spinning operation, a continuous operation was performed for 10 hours in the same manner as in Example 1, but on the way, stable spinning was possible without cutting.

In the heating furnace which set obtained polyimide single yarn E to 230 degreeC, it extended | stretched once under the conditions similar to Example 1, and obtained stretched yarn E2.

Next, heat-treated stretched yarn E2 was obtained under the same conditions as in Example 1 in a heating furnace set at 200 ° C.

The result of having carried out stability test on the obtained polyimide fiber by the method similar to Example 1 is shown in a 1st table | surface.

Example 3

In the same reaction vessel as in Example 1, 2,2-bis [4- (3-aminophenoxy) phenyl) propane 410 (1.0 mole) and 6500 g of N, N-dimethylacetamide were charged, and the nitrogen atmosphere was changed to room temperature. 312.34 (0.97 mol) of 3,3 ', 4,4'-benzophenonetecarboxylic acid dianhydride (BTDA) was added to the mixture, paying attention to an increase in solution temperature, and the mixture was stirred at room temperature for about 20 hours.

37.8 g (0.15 mol) of 3, 4- benzophenone dicarboxylic anhydrides were added to this polyimide acid solution at room temperature under nitrogen atmosphere, and it stirred for further 1 hour. Next, 404 g (4 mol) triethylamine and 306 g (3 mol) acetic anhydride were dripped at this solution. After completion of the dropwise addition, stirring was continued for about 10 hours, and then discharged and separated into about 10 kg of methanol. After dispersion | distribution washing | cleaning in methanol, it separated by filtration, and it dried and dried at 180 degreeC for 6 hours, and obtained 676 kg of polyimide powder. This polyimide did not show crystallinity, and the glass transition temperature Tg shown in FIG. 1 was 0.49 dl / g according to the logarithmic viscosity measurement method shown in Example 1 at 190 ° C.

The polyimide powder thus obtained was obtained in the same manner as in Example 1 to obtain a polyimide pellet under the condition of a heating tube temperature of 340 ° C., and then to obtain a polyimide single yarn G having a diameter of 270 μm. During the above operation, in the same manner as in Example 1, the operation was performed continuously for 10 hours, but no cutting was performed on the way and stable spinning was possible.

In the heating furnace which set obtained polyimide single yarn G to 210 degreeC, it extended | stretched once on the conditions similar to Example 1, and obtained stretched yarn G1.

Next, heat-treated stretched yarn G2 was obtained under the same conditions as in Example 1 in a heating furnace set to 180 ° C.

The result of having performed the tension test to the obtained polyimide fiber by the method similar to Example 1 is shown in a 1st table | surface.

Comparative Example 1

In the same manner as in Example 1, 529 g of polyimide powder was obtained without performing an operation of reacting phthalic anhydride.

The glass transition temperature Tg shown in FIG. 1 of this polyimide powder was 260 degreeC, the melting temperature Tm was 385 degreeC, and the crystallization temperature Tc was 312 degreeC. Moreover, the logarithmic viscosity of the obtained polyimide powder was 0.52 dl / g. Extrusion pelletization and melt spinning were performed in the same manner as in Example 1 using the polyimide thus obtained.

During the continuous operation of the melt spinning, the indication of the pressure gauge installed in front of the filter was 50 kg / cm 2 at the start of operation, but it increased to 100 kg / cm 2 after 1 hour and 200 kg / cm 2 after 1.5 hours, There is a risk of exceeding the torque capability and the operation has been stopped. After 30 minutes from the start of continuous operation, the cut-out shape began to occur, and after 1 hour, the broken cut occurred, and continuous spinning became impossible.

During this operation, a relatively good polyimide single yarn C having a diameter of 350 µm in the initial stage of operation and a polyimide single yarn D having a diameter of 330 µm in the period which was not occasionally cut at a stage after 1 hour were obtained. Compared with the polyimide single yarns A, B and C, the polyimide single yarn D had no gloss in the surface appearance, and many of the nodes considered to be gelates were seen on the surface.

Polyimide single yarns C and D obtained in this manner were stretched in the same manner as in Example 1, but D was broken during stretching and no stretched yarn was obtained. Polyimide single yarn C was extended | stretched under 240 degreeC and 280 degreeC, and the stretched yarn C1 and C2 were obtained. This stretched yarn C1 and C2 were heat-treated under 300 degreeC, and C3 and C4 were obtained. The results measured for the tensile strength and tensile elongation (JIS-L-1813 (1981)) of the obtained polyimide fibers are shown in the first table.

Comparative Example 2

In the same manner as in Example 2, 550 g of polyimide powder was obtained without performing an operation of reacting phthalic anhydride.

The glass transition temperature Tg shown in FIG. 1 of this polyimide powder was 215 degreeC. Moreover, the logarithmic viscosity of the obtained polyimide powder was 0.49 dl / g. Extrusion pelletization and melt spinning were performed in the same manner as in Example 1 using the polyimide obtained as described above.

While performing the melt spinning in continuous operation, the indication of the pressure gauge for resin installed in front of the filter was 50 kg / cm 2 at the start of operation, but it increased to 100 kg / cm 2 after 40 minutes to 200 kg / cm 2 after 1.0 hour, and the rated torque capability of the extruder was increased. There is a risk of exceeding and the operation has been stopped. In addition, a thread breaking phenomenon started to occur 20 minutes after the start of continuous operation, and after 30 minutes had elapsed, the actual stage was crowded and continuous spinning was impossible.

During this operation, a relatively good polyimide single yarn F of 300 mu m in diameter was obtained in the initial stage of operation. Compared with polyimide acid yarn E, the polyimide single yarn F had no gloss in the surface appearance, and a lot of nodes appeared to be gelled on the surface.

Thus, polyimide single yarn F obtained was extended | stretched on the conditions similar to Example 2, and twisted yarn F1 was obtained.

The stretched yarn F1 was heat-treated under the same conditions as in Example 2, and the results of the measurement of the tensile strength and the tensile elongation of the polyimide fiber obtained with F2 are shown in the first table.

Comparative Example 3

In the same manner as in Example 3, 665 g of polyimide powder was obtained without performing the operation of reacting only 3,4-benzonondicarboxylic acid.

The glass transition temperature Tg shown in FIG. 1 of this polyimide powder was 198 degreeC. Moreover, the logarithmic viscosity of the obtained polyimide powder was 0.47 dl / g. Extrusion pelletization and melt spinning were performed in the same manner as in Example 1 using the polyimide thus obtained.

While performing melt spinning in continuous operation, the indication of the pressure gauge for resin installed in front of the filter was 50 kg / cm 2 at the start of operation, but rose to 100 kg / cm 2 after 45 minutes and 200 kg / cm 2 after 60 minutes, and rated torque capability of the extruder. There is a risk of exceeding and the operation has been stopped. In addition, after 20 minutes from the start of the continuous operation, the actual cutting phenomenon starts

After 30 minutes elapsed, a lot of cuts occurred, and continuous spinning was impossible.

During this operation, a relatively good polyimide single yarn H having a diameter of 30 µm was obtained in the initial stage of operation. Compared with polyimide single yarn G, polyimide single yarn H had no gloss in the surface appearance, and a lot of nodes appeared to be gelled on the surface.

Thus, polyimide single yarn H obtained was stretched under the same conditions as in Example 3 to obtain stretched yarn H1. This stretched yarn H1 was heat-treated under the same conditions as in Example 3 to obtain H2. The result measured about the tensile strength and tensile strength of the obtained polyimide fiber is shown in a 1st table | surface. As shown in the first table, the Examples and Comparative Examples have the same tensile strength and tensile elongation.

TABLE 1

A… Single yarn diameter 300 mu m, B... Single yarn diameter of 100 mu m, E... Single yarn diameter 250 mu m, G... Single yarn diameter 270㎛

C… Initial extrusion operation, single yarn diameter 350㎛, D… After 1 hour of extrusion operation, single yarn diameter 330㎛

F… Initial extrusion operation, unit diameter 300㎛, H… Initial extrusion operation, single diameter 300㎛

[Examples 1-3]

Polyimide pellets are obtained by the same polymerization and processing processes shown in Examples 1 to 3. The pellet is dried in a hot air circulation dryer at 200 ° C. for 16 hours, and then polyimide single yarns A, B, E, and G are obtained by the screw type extrusion operation shown in Example 1. During the extrusion operation, the hopper is sealed to prevent moisture absorption of the pellets.

The water content of the pellet at the time of hopper injection is shown in the following table. In addition, 2 g of pellets were put into a 300 ° C. heating furnace passing 100 [ml / min] nitrogen as a carrier gas, and the gas was passed through the zero-adjusted methanol for 5 minutes. Value obtained by titration with Fischer's reagent).

Comparative Experimental Examples 1-3

Polyimide pellets are obtained by the same polymerization and processing processes shown in Examples 1 to 3. The pellet is left at room temperature for 7 days, and then dried in a 100 ° C. hot air purifying dryer for 16 hours. Polyimide single yarns a, b, e, g are obtained by the extrusion operation shown in Example 1. During pressure operation, the hopper is sealed and the water hops of the pellets are suppressed as much as possible.

The water content and extrusion situation of the pellet at the time of the hopper injection are as follows.

Claims (16)

In the method for producing a polyimide fiber comprising thermally or chemically imidating a polyimide acid obtained by reacting a diamine with terracarboxylic dianhydride, and spinning the polyimide acid or polyimide after imidization thereof , (A) Diamine is represented by the following formula (I)

(Wherein X represents a group selected from the group consisting of a direct link, two hydrocarbon groups having 1 to 10 carbon atoms, an isopropylidene group, a carbonyl group, a thio group, or a sulfonyl group) Containing diamine represented by (b) and tetracarboxylic dianhydride is represented by the following formula (II)

(Wherein R is a tetravalent group selected from the group consisting of aliphatic groups having 2 or more carbon atoms, cycloaliphatic groups, monocyclic aromatic groups, condensed polyaromatic groups, and non-condensed polyaromatic groups in which aromatic groups are interconnected by direct or crosslinking sources) Display) Tetracarboxylic acid dianhydride represented by (c) or the reaction is represented by the following formula (III)

(Wherein Z represents a divalent group selected from the group consisting of a monocyclic aromatic group, a condensed polyaromatic group, and a non-condensed polyaromatic group in which the aromatic groups are directly or interconnected by a bridging member) (D) The amount of tetracarboxylic dianhydride used is 0.9 to 1.0 mole per mole of diamine used, and the amount of dicarboxylic acid anhydride used is 0.001 per mole of diamine used. The following formula (IV) which is -1.0 molar ratio.

Wherein X and R are as defined above. A method for producing a polyimide fiber, characterized in that the water content of the polyimide and / or polyimide acid before passing the repeated anti-toxic unit expressed by the basic skeleton and before the melt spinning is defined as 200 ppm or less. The method for producing a polyimide fiber according to claim 1, wherein X is directly linked. The method for producing a polyimide fiber of claim 1, wherein X is a divalent hydrocarbon group having 1 to 10 carbon atoms. The compound of claim 1, wherein X is -CH _2- ,

, -CH ₂ CH _2- ,

or

Method for producing phosphorus polyimide fiber. The method for producing a polyimide fiber according to claim 1, wherein X is an isopropyldene group hexafluorinated. The method for producing a polyimide fiber according to claim 1, wherein X is a carbonyl group, a thio group, or a sulfonyl group. The diamine represented by the formula (I) according to claim 1 is 4,4'-bis (3-aminophenoxy) biphenyl, 2,2-bis [4- (3-aminophenoxy) phenyl] propane And bis [4- (3-aminophenoxy) phenyl] sulfone. The method for producing a polyimide fiber according to claim 1, wherein R is an aliphatic group or a cyclic aliphatic group having 2 or more carbon atoms. The method for producing a polyimide fiber according to claim 1, wherein R is a monocyclic aromatic group, a condensed polycyclic aromatic group, or a non-condensed polycyclic aromatic group in which the aromatic groups are directly or interconnected by a crosslinking source. The method for producing a polyimide fiber according to claim 1, wherein R is a monocyclic aromatic group. The method for producing a polyimide fiber according to claim 1, wherein the tetracarboxylic dianhydride represented by formula (II) is pyromellitic dianhydride, 3,3 ', 4,4'-benzonontetracarboxylic dianhydride. The method for producing a polyimide fiber according to claim 1, wherein Z is a monocyclic aromatic group. The method for producing a polyimide fiber according to claim 1, wherein the amount of dicarboxylic acid anhydride used is 0.01 to 0.5 mol per mol of diamine used. The method for producing a polyimide fiber according to claim 1, wherein the glass transition temperature Tg of the polyimide is 235 to 265 캜. The method for producing a polyimide fiber according to claim 1, wherein stretching and heat treatment are performed after spinning. Polyimide fibers obtained by the method of claim 1.

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