JP3327920B2 - Method for producing polyimide having good moldability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyimide resin for melt molding, and more particularly, to a polyimide resin having good heat stability and excellent moldability such as extrusion and injection molding. It relates to a manufacturing method.

[Conventional technology]

Conventionally, polyimide obtained by the reaction of tetracarboxylic dianhydride and diamine, in addition to its high heat resistance,
It has excellent mechanical strength, dimensional stability, flame retardancy, electrical insulation, etc.
It is used in fields such as transportation equipment and is expected to be widely used in fields where co-heat resistance is required in the future.

Conventionally, various polyimides exhibiting excellent characteristics have been developed.

However, even if it is excellent in heat resistance, it does not have a clear glass transition temperature, so if it is used as a molding material, it must be processed using a method such as sintering molding, and the workability is excellent However, it has a low glass transition temperature, is soluble in halogenated hydrocarbons, and is not satisfactory in terms of heat resistance and solvent resistance, and has advantages and disadvantages in performance.

On the other hand, TLSt.Clair Proger and the like are polyimides having excellent mechanical properties, thermal properties, electrical properties, solvent resistance, etc., and having heat resistance as shown in the following general formulas (V) and (V).
I) (In the formula, R is an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or an aromatic group connected directly or by a crosslinking member. A polyimide having a repeating structural unit represented by the following formula (indicating a tetravalent group selected from the group consisting of non-fused polycyclic aromatic groups) (Int. J. Adhesion and Adhesive 4 , No 2, April) 198
4, and JP-A-62-53372).

The above polyimide is a novel heat resistant resin having many good physical properties.

However, the above-mentioned polyimide shows excellent fluidity and has good processability, but its melt viscosity is higher than that of engineering plastics which can be usually extruded and injection-molded, so that injection and extrusion molding can be performed. Because of the difficulty, the only method for producing films and the like is in the state of polyamic acid and by the casting method.

[Problems to be solved by the invention]

An object of the present invention is to provide a method for producing a polyimide having excellent moldability in addition to excellent characteristics inherent to polyimide.

[Means for solving the problem]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and achieved the present invention.

That is, the present invention relates to (a) the general formula (I) (Wherein, X represents a divalent group of —CO— or —SO ₂ —)
An aromatic diamine represented by the general formula (II): (Where R is A tetracarboxylic dianhydride represented by a tetravalent group selected from the group consisting of: (c) a general formula (III) Z-NH ₂ (III) (wherein Z is An aliphatic and / or cycloaliphatic monoamine represented by the formula (II): (d) the amount of the aromatic diamine is one mole per mole of tetracarboxylic dianhydride The polyamic acid obtained by reacting the polyamic acid at a molar ratio of 0.9 to 1.0 and the amount of the aliphatic and / or cycloaliphatic monoamine in a molar ratio of 0.001 to 1.0 per mol of tetracarboxylic dianhydride is thermally or chemically reacted. General formula (IV) (Wherein, X and R have the same meanings as described above). A method for producing a polyimide for extrusion / injection molding, comprising a repeating structural unit represented by the formula:

The diamine used in the method of the present invention has the general formula (I)
Are used, ie, bis (3-aminophenyl) sulfone or 3,3′-diaminobenzophenone. Further, as long as the good physical properties of the polyimide obtained by the method of the present invention are not impaired, some of the above diamines may be used instead of other diamines. Examples of the diamine compound that can be used as a partial substitute include, for example, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, bis (3-aminophenyl) ether, (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) sulfide (Aminophenyl) sulfoxide, (3-aminophenyl) (4-aminophenyl) sulfoxide, bis (4-aminophenyl) sulfoxide, (3-aminophenyl) (4-aminophenyl) sulfone, bis (4-
Aminophenyl) sulfone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane,
4,4'-diaminodiphenylmethane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-
Aminophenoxy) phenyl] methane, 1,1-bis [4
-(3-aminophenoxy) phenyl] ethane, 1,1-
Bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4-
(4-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- (4-aminophenoxy) phenyl] butane, 2,2-bis [4-
(3-Aminophenoxy) phenyl] -1,1,1,3,3,3-
Hexafluoropropane, 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 (3-aminophenoxy) benzene, 1,4
-Bis (4-aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-bis (4
-Aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) -3,3'-dimethylbiphenyl, 4,4'-
Bis (3-aminophenoxy) -3,5'-dimethylbiphenyl, 4,4'-bis' (3-aminophenoxy) -3,5'-
Dimethylbiphenyl, 4,4'-bis (3-aminophenoxy) -3,3 ', 5,5'-tetramethylbiphenyl, 4,4'-bis (3-aminophenoxy) -3,3'-dichlorobiphenyl , 4,4'-bis (3-aminophenoxy) -3,5'-dichlorobiphenyl, 4,4'-bis (3-aminophenoxy)
-3,3 ', 5,5'-tetrachlorobiphenyl, 4,4'-bis (3-aminophenoxy) -3,3'-dibromobiphenyl, 4,4'-bis (3-aminophenoxy) -3 , 5'-dibromobiphenyl, 4,4'-bis (3-aminophenoxy)
−3,3 ′, 5,5′-tetrabromobiphenyl, bis [4-
(4-aminophenoxy) phenyl] ketone, bis [4
-(3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl ] -3-methoxyphenyl] sulfide, [4- (3
-Aminophenoxy) phenyl] [4- (3-aminophenoxy) -3,5-dimethoxyphenyl] sulfide,
Bis [4- (3-aminophenoxy) -3,5-dimethoxyphenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [ 4-
(3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone,
Bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3- Bis [4- (3-aminophenoxy) benzoyl] benzene, 4,4'-bis [3-
(4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-
Amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-
Dimethylbenzyl) phenoxy] diphenylsulfone,
Bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone and the like are used, and these are used alone or in combination of two or more.

Examples of the tetracarboxylic dianhydride represented by the general formula (II) used in the method of the present invention include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid Acid dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3 -Hexafluoropropane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 4,4 '-(p- And phenylenedioxy) diphthalic dianhydride. These may be used alone or in combination of two or more.

Examples of the aliphatic and / or cycloaliphatic monoamine represented by the general formula (III) used in the method of the present invention include, for example, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine ,
Isobutylamine, sec-butylamine, tert-butylamine, n-amylamine, isoamylamine, tert-
Amylamine, hexylamine, heptylamine, octylamine, 2-ethylhexylamine, nonylamine, decylamine, cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine, cyclohexanemethylamine, and the like. The aliphatic monoamine and / or the cycloaliphatic monoamine may be used alone or in combination of two or more.

The molar ratio of tetracarboxylic dianhydride, aromatic diamine compound and aliphatic monoamine and / or cycloaliphatic monoamine (hereinafter, simply referred to as monoamine) used in the method of the present invention is tetracarboxylic dianhydride. The aromatic diamine is 0.9 to 1.0 mole and the monoamine is 0.001 to 1.0 mole per mole.

That is, in the production of polyimide, in order to adjust the molecular weight of the produced polyimide, it is customary to adjust the ratio of tetracarboxylic dianhydride to aromatic diamine. In the method of the present invention, in order to obtain a polyimide having good melt fluidity, the molar ratio of the aromatic diamine to the tetracarboxylic dianhydride is set to 0.9 to 1.0.

The monoamine to be coexisted is used in a molar ratio of 0.001 to 1.0 based on tetracarboxylic dianhydride. 0.
If the molar ratio is less than 001, good moldability cannot be obtained.
On the other hand, when the molar ratio exceeds 1.0, the mechanical properties of the obtained polyimide deteriorate. Preferred amounts are in the range of 0.01 to 0.5 molar ratio.

In the method for obtaining the polyimide of the present invention, the reaction method is not particularly limited, and a known method is used, but it is particularly preferable to perform the reaction in an organic solvent.

As the organic solvent used in this reaction, for example, N, N-
Dimethylformamide, N, N-dimethylacetamide,
N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, 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-
Examples thereof include dioxane, pyridine, picoline, dimethyl sulfoxide, dimethyl sulfone, tetramethyl urea, hexamethyl phosphoramide, phenol, p-chlorophenol, m-cresol, p-cresol, o-cresol, cresylic acid, and anisole. These organic solvents may be used alone or in combination of two or more.

In the method of the present invention, the method of reacting tetracarboxylic dianhydride, aromatic diamine and monoamine includes: (a) reacting tetracarboxylic dianhydride with aromatic diamine and then adding monoamine to react (B) a method in which a monoamine is added to and reacted with tetracarboxylic dianhydride, and then an aromatic diamine is added and the reaction is further continued; (c) tetracarboxylic dianhydride, aromatic diamine; Any addition method, such as a method of simultaneously adding and reacting monoamines, may be used.

The reaction temperature is usually 0 ° C. to 250 ° C., and preferably a temperature of 60 ° C. or less.

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

The reaction time varies depending on the type of tetracarboxylic dianhydride, aromatic diamine, monoamine, solvent used and the reaction temperature, and usually 4 to 24 hours is sufficient.

By such a reaction, a polyimide acid which is a repeating structural unit represented by the following general formula (VII) is generated.

(Wherein X and R are the same as described above). The polyamic acid is heated to 100 to 400 ° C. for imidization, or a commonly used imidizing agent such as triethylamine and acetic anhydride is used. By performing chemical imidization using the compound, a corresponding polyimide which is a repeating structural unit represented by the general formula (IV) is obtained.

(In the formula, X and R are the same as described above.) Generally, after a polyimide acid is formed at a low temperature, it is further thermally or chemically imidized.

As another method, a polyimide can be obtained by simultaneously performing the generation of the polyimide acid and the thermal imidization reaction at a temperature of 60 ° C. to 250 ° C.

That is, after a tetracarboxylic dianhydride, an aromatic diamine and a monoamine are suspended or dissolved in an organic solvent, the reaction is carried out under heating, and the polyamic acid is generated and the dehydration imidization is simultaneously performed to obtain the general formula ( A polyimide comprising a repeating structural unit represented by IV) can also be obtained.

When subjecting the polyimide obtained by the method of the present invention to melt molding, other thermoplastic resins within a range not impairing the purpose, for example, polyethylene, polypropylene, polycarbonate, polyarylate, polyamide, polysulfone, polyethersulfone, polyetherketone , Polyphenylene sulfide, polyamide imide, polyether imide, modified polyphenylene oxide, etc., in an appropriate amount depending on the purpose.

Further, the following fillers and the like used in ordinary resin compositions may be used to the extent that the purpose is not impaired.
That is, graphite, carborundum, silica stone powder,
Abrasion resistance improvers such as molybdenum disulfide and fluororesin,
Glass fiber, carbon fiber, boron fiber, silicon carbide fiber, carbon whisker, asbestos, metal fiber, ceramic fiber, etc., reinforcing materials such as antimony trioxide, magnesium carbonate, calcium carbonate, etc., clay, mica, etc. Electrical property improver, tracking resistance improver such as asbestos, silica, graphite, etc., acid resistance improver such as barium sulfate, silica, calcium metasilicate, etc., thermal conductivity improvement of iron powder, zinc powder, aluminum powder, copper powder, etc. Agents, other glass beads, glass balls, talc,
Diatomaceous earth, alumina, shirasubarun, hydrated alumina, metal oxides, coloring agents and the like.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1 322 g (1.0 mol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and N, N-dimethylacetamide 31 were placed in a vessel equipped with a stirrer, a reflux condenser and a nitrogen inlet tube.
90 g (1.0 mol) was charged, and at room temperature under a nitrogen atmosphere, bis (3-aminophenyl) sulfone 240.6 g (0.97 mol)
Was added in portions, paying attention to the rise in solution temperature, and the mixture was stirred at room temperature for about 20 hours. To this polyamic acid solution was added 9.11 g (0.09 mol) of n-hexylamine at room temperature under a nitrogen atmosphere, and the mixture was further stirred for 1 hour. Then 202 g (2 mol) of triethylamine and 306 g (3
Mol) of acetic anhydride was added dropwise. About one hour after the completion of the dropping, yellow polyimide powder began to precipitate. The mixture was further stirred at room temperature for 10 hours and filtered.

Further, it was dispersed and washed in methanol, filtered, and dried at 180 ° C. for 2 hours to obtain 506 g of a polyimide powder. The glass transition temperature of this polyimide powder was 269 ° C. The logarithmic viscosity of this polyimide powder was 0.51 d /. Here, the logarithmic viscosity is a value measured at 35 ° C. using a mixed solvent of parachlorophenol and phenol (weight ratio 90:10) with a solvent having a concentration of 0.5 g / 100 m.

Using the polyimide powder obtained in the present example, a Koka type flow tester (Shimadzu Corporation, CFT-500, orifice diameter 0.
(1 cm, length 1 cm), the relationship between melt viscosity and pressure (shear rate) was measured. FIG. 1 shows the relationship between the melt viscosity and the shear rate measured after variously changing the shear rate after maintaining the temperature at 380 ° C. for 5 minutes.

Comparative Example 1 500 g of polyimide powder was obtained in exactly the same manner as in Example 1 except that the operation of reacting n-hexylamine was not performed.

The logarithmic viscosity of the obtained polyimide powder was 0.51 d / g.

Using this polyimide powder, the melt viscosity was measured with a flow tester in the same manner as in Example 1, and the results shown in FIG. 1 were obtained.

Compared to the polyimide powder obtained in Example 1, the melt viscosity in the low shear rate region was higher, and it was found that the processability was poor.

Example 2 A reaction apparatus similar to that of Example 1 was charged with 322 g (1.0 mol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and 3200 g of N, N-dimethylacetamide, and cyclohexylamine was added. 5.95 g (0.06 mol) was added and stirred for about 20 minutes.

Then, bis (3-aminophenyl) sulfone 240.
6 g (0.97 mol) was added while paying attention to the rise of the solution temperature.
Stir at room temperature for about 10 hours.

Then, 202 g (2 mol) of triethylamine and 255 g (2.5 mol) of acetic anhydride were added dropwise to the solution. The mixture was stirred at room temperature for 10 hours to obtain a pale yellow slurry. The slurry was separated by filtration, washed with methanol, and dried under reduced pressure at 180 ° C. for 8 hours to obtain 507 g of a pale yellow polyimide powder. The glass transition temperature of this polyimide powder is 269 ° C and the logarithmic viscosity is 0.52d
/ g.

The thermal stability of the polyimide obtained in this example was tested by changing the residence time in the cylinder of the flow tester and measuring the melt viscosity. Cylinder temperature was 380 ° C. and pressure was 100 kg / cm ² .

The results are shown in FIG. Even if the residence time in the cylinder becomes longer, the melt viscosity hardly changes, indicating that the thermal stability is good.

Comparative Example 2 A pale yellow polyimide powder was obtained in exactly the same manner as in Example 2, but without using cyclohexylamine.

The logarithmic viscosity of the polyimide powder was 0.52 d / g, and the glass transition temperature was 269 ° C.

When the residence time in the flow tester cylinder was changed and the melt viscosity was measured in the same manner as in Example 2, the melt viscosity increased as the residence time became longer, and the thermal stability was higher than that of the polyimide obtained in Example 2. Was inferior. The results are shown in FIG.

Example 3 In the same reactor as in Example 1, pyromellitic dianhydride 218 g (1.0 mol), bis (3-aminophenyl) sulfone 233 g (0.94 mol), n-octylamine 15.5 g (0.1 mol)
2 mol) and 3460 g of m-cresol, and the mixture was gradually heated and heated under stirring in a nitrogen atmosphere. After stirring at 150 ° C. for 3 hours, the precipitated polyimide was filtered.

This polyimide powder is mixed with methanol and acetone for 1 each.
After washing twice, it was dried under reduced pressure at 180 ° C. for 8 hours to obtain 413 g of polyimide powder.

The glass transition temperature of this polyimide powder was 302 ° C., and the logarithmic viscosity was 0.40 d / g.

Temperature 420 ° C., by a flow tester under a pressure 100 kg / cm ^2,
The melt viscosity was measured repeatedly. That is, an experiment in which a strand obtained by extruding at 420 ° C. was pulverized and measured again with a flow tester was repeated five times. Almost no change in viscosity due to the number of measurements was observed. FIG. 3 shows the results.

Example 4 In the same reactor as in Example 1, 240.6 g (0.97 mol) of bis (3-aminophenyl) sulfone in Example 1
Was replaced with 206 g (0.97 mol) of 3,3'-diaminobenzophenone, and the reaction was carried out in exactly the same manner to obtain a polyamic acid solution. 12.15 g (0.12 mol) of n-hexylamine was added to this polyamic acid solution at room temperature under a nitrogen atmosphere, and the mixture was further stirred for 1 hour. Then, to this solution, 202 g (2 mol) of triethylamine and 306 g (3 mol) of acetic anhydride were added dropwise. About one hour after the completion of the dropping, yellow polyimide powder began to precipitate. The mixture was further stirred at room temperature for 10 hours and filtered.

Further, the dispersion was washed with methanol, separated by filtration, and dried at 180 ° C. for 2 hours to obtain 473 g of a polyimide powder. This polyimide powder had a glass transition temperature of 250 ° C. and a melting point of 298 ° C. (according to DSC; the same applies hereinafter). The logarithmic viscosity of this polyimide powder was 0.52 d / g.

The relationship between the melt viscosity and the pressure (shear rate) was measured in the same manner as in the examples. FIG. 4 shows the relationship between the melt viscosity and the shear rate measured by changing the shear rate after keeping the temperature at 380 ° C. for 5 minutes.

FIG. 4 shows the relationship between the number of repetitions and the melt viscosity. Even if the number of repetitions was increased, there was almost no change in the melt viscosity, indicating good molding stability.

Comparative Example 3 463 g of a polyimide powder was obtained in exactly the same manner as in Example 4 except that the operation of reacting n-hexylamine was not performed.

The logarithmic viscosity of the obtained polyimide powder was 0.52 d / g.

Using this polyimide powder, the melt viscosity was measured with a flow tester in the same manner as in Example 4, and the results shown in FIG. 4 were obtained.

It can be seen that the melt viscosity is higher in the low shear rate region than in Example 4, and the molding processability is inferior to that of the polyimide obtained in Example 4.

Example 5 322 g (1.0 mol) of 3,3, ', 4,4'-benzophenonetetracarboxylic dianhydride, 3000 g of N, N-dimethylacetamide and 5.95 g of cyclohexylamine were placed in the same reactor as in Example 1. 0.06 mol), and 206 g (0.97 mol) of 3,3'-diaminobenzophenone was added at room temperature under a nitrogen atmosphere while paying attention to the rise in solution temperature, followed by stirring at room temperature for about 20 hours.

Then, to this solution, 202 g (2 mol) of triethylamine and 306 g (3 mol) of acetic anhydride were added dropwise. The mixture was stirred for 20 hours to obtain a pale yellow slurry.

The slurry is filtered, washed with methanol, and
For 8 hours to obtain 473 g of pale yellow polyimide powder. The glass transition temperature of this polyimide powder was 250 ° C., the melting point was 298 ° C., and the logarithmic viscosity was 0.50 d / g.

The molding stability of the polyimide obtained in this example was measured by changing the residence time in the cylinder of the flow tester. The temperature was 380 ° C. and the pressure was 100 kg / cm ² .

The results are shown in FIG. Even if the residence time in the cylinder becomes longer, the melt viscosity hardly changes, indicating that the thermal stability is good.

Comparative Example 4 A pale yellow polyimide powder was obtained in exactly the same manner as in Example 5, except that cyclohexylamine was not used.

The logarithmic viscosity of the polyimide powder was 0.50 d / g, and the glass transition temperature was 250 ° C.

When the residence time in the flow tester cylinder was changed and the melt viscosity was measured in the same manner as in Example 5, the melt viscosity increased as the residence time became longer.
Was inferior in thermal stability to the polyimide obtained in 1. The results are shown in FIG.

Example 6 In a reactor similar to that in Example 1, 3,7.8′-diaminobenzophenone (207.8 g, 0.98 mol), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride 322 g (1.0 mol) ), N-
5.17 g (0.04 mol) of octylamine and 3000 g of m-cresol were charged, and the temperature was gradually increased while stirring under a nitrogen atmosphere. At about 120 ° C., a brown transparent homogeneous solution was obtained. Heat to 150 ° C and continue stirring, about 20
Minutes later, polyimide powder began to precipitate. The mixture was further stirred for 2 hours under heating, and then filtered to obtain a polyimide powder.

This polyimide powder is mixed with methanol and acetone for 1 each.
After washing twice, it was dried under reduced pressure at 180 ° C. for 8 hours to obtain 479 g of polyimide powder.

The glass transition temperature of this polyimide powder is 251 ° C, and the melting point is 2
At 98 ° C., the logarithmic viscosity was 0.57 d / g.

As in Example 1, the melt viscosity was measured by extrusion at a temperature of 400 ° C. and a pressure of 100 kg / cm ² repeatedly using a flow tester. Almost no change in viscosity due to the number of measurements was observed. FIG. 6 shows the results.

〔The invention's effect〕

According to the method of the present invention, there is provided a polyimide having excellent mechanical properties, thermal properties, electrical properties, solvent resistance, heat resistance, thermal stability for a long time, and excellent moldability. be able to.

[Brief description of the drawings]

1 and 4 show the relationship between the melt viscosity and the shear rate of the polyimide produced by the method of the present invention. FIG. 1 shows the measurement results for the polyimides obtained in Example 1 and Comparative Example 1. FIG. 4 shows the measurement results for the polyimides obtained in Example 4 and Comparative Example 3. 2 and 5 show the relationship between the melt viscosity of the polyimide produced by the method of the present invention and the residence time in a cinder, and FIG. 2 shows the measurement of the polyimide obtained in Example 2 and Comparative Example 2. As a result, FIG. 5 shows the measurement results for the polyimides obtained in Example 5 and Comparative Example 4. FIGS. 3 and 6 show the results of the measurement of the relationship between the number of repetitions of melting and the melt viscosity of the polyimide produced by the method of the present invention. FIG. 3 shows the polyimide obtained in Example 3, FIG. Is the measurement result for the polyimide obtained in Example 6.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-95030 (JP, A) JP-A-60-258229 (JP, A) JP-A-1-131238 (JP, A) JP-A 61-950 95029 (JP, A) JP-A-61-78834 (JP, A) JP-A-1-138265 (JP, A)

Claims (1)

(57) [Claims] (1) General formula (I) (Wherein, X represents a divalent group of —CO— or —SO ₂ —)
An aromatic diamine represented by the general formula (II): (Where R is A tetracarboxylic dianhydride represented by a tetravalent group selected from the group consisting of: (c) a general formula (III) Z-NH ₂ (III) (wherein Z is An aliphatic and / or cycloaliphatic monoamine represented by the formula (II): (d) the amount of the aromatic diamine is one mole per mole of tetracarboxylic dianhydride The polyamic acid obtained by reacting the polyamic acid at a molar ratio of 0.9 to 1.0 and the amount of the aliphatic and / or cycloaliphatic monoamine in a molar ratio of 0.001 to 1.0 per mol of tetracarboxylic dianhydride is thermally or chemically reacted. General formula (IV) (Wherein, X and R have the same meanings as described above). A method for producing a polyimide for extrusion / injection molding, comprising a repeating structural unit represented by the formula: