JP2000302865A - Preparation of polyimide resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preparation process of a polyimide resin having an excellent heat resistance, which utilizes an inexpensive monomer and does not use any solvent. SOLUTION: One or two or more tetracarboxylic acid components chosen from the group consisting of a tetracarboxylic acid which forms two imide rings after ring closure, tetracarboxylic acid monoanhydride and tetracarboxylic acid dianhydride, is mixed with a diamine without using any solvent and subsequently heated. Preferably, the above tetracarboxylic acid component and the diamine are mixed at a molar ratio of (0.8-1.2):1, and the heat treatment is carried out at from 80 to 450 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a polyimide resin applicable to heat-resistant films, heat-resistant molded products, adhesives, etc. without using a solvent.

[0002]

2. Description of the Related Art Conventionally, a polyimide resin is prepared by reacting tetracarboxylic dianhydride with a diamine in an organic solvent.
A polyamic acid solution was formed and then heated or chemically closed to obtain a polyamic acid solution. According to this method, usually, a highly polar organic solvent in which the polyamic acid can be dissolved must be used, but these are mostly expensive and harmful, and the number of production steps is large. Also, the tetracarboxylic dianhydride to be used contains impurities that have been opened by reacting with moisture, or react with moisture in the air before use to form a carboxylic acid by ring opening and lose reactivity. It was necessary to obtain high-purity tetracarboxylic dianhydride and maintain the purity to prevent the influence of moisture. Similarly, many reaction solvents easily absorb moisture in the air,
It also becomes a factor of reducing the reactivity of the tetracarboxylic dianhydride during the reaction, and an expensive high-purity organic solvent must be obtained to prevent moisture absorption.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems of the conventional method for synthesizing a polyimide resin, which was synthesized using an organic solvent and via a polyamic acid. It is an object of the present invention to provide a synthesis method capable of easily obtaining a polyimide resin having excellent heat resistance and mechanical strength by using inexpensive raw materials.

[0004]

That is, the present invention relates to a compound selected from the group consisting of tetracarboxylic acids, tetracarboxylic monoanhydrides and tetracarboxylic dianhydrides capable of forming two imide rings after ring closure. After mixing the kind or two or more kinds of tetracarboxylic acid components and the diamine without using a solvent,
This is a method for producing a polyimide resin, which is characterized by performing a heat treatment.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The tetracarboxylic dianhydride used in the present invention includes pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, oxydiphthalic dianhydride,
In addition to aromatic tetracarboxylic dianhydrides such as 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride, aliphatic tetracarboxylic acids such as cyclobutanetetracarboxylic dianhydride and cyclopentanetetracarboxylic dianhydride Carboxylic dianhydrides can also be used, but are not limited thereto. Further, one or two or more of them can be used in appropriate combination.

In addition, the tetracarboxylic acid and tetracarboxylic monoanhydride capable of forming two imide rings after ring closure used in the present invention are prepared by reacting the above tetracarboxylic dianhydride with water to open the ring. And may be derived from an aromatic tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride.

[0007] That is, in the present invention, it means that a partially-opened monoanhydride or tetracarboxylic acid may be mixed as an impurity into the tetracarboxylic dianhydride. It is also possible to mix these positively. Therefore, in the conventional solution reaction via a polyamic acid, unless a polyimide-grade high-purity tetracarboxylic dianhydride is used, the reaction rate is reduced and sufficient cured product properties cannot be obtained. However, according to the present invention, an inexpensive low-purity product can be used.

The diamine used in the present invention includes:
4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 4,4′-methylenedi-o-toluidine,
4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4 '
-Diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide,
3,3′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl ether,
3,3′-diaminodiphenyl ether, benzidine,
3,3'-diaminobiphenyl, 3,3'-dimethyl-4,
4′-diaminobiphenyl, 3,3′-dimethoxybenzidine, bis (p-aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) )benzene,
p-bis (2-methyl-4-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2,4-diamino Toluene, m-xylene-2,5
-Diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-
Diaminopyridine, 2,5-diaminopyridine, 2,5-
Diamino-1,3,4-oxadiazole, 1,4-diaminocyclohexane, piperazine, methylenediamine,
Ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,5-dimethylhexamethylenediamine, 3-methoxyhexamethylenediamine, heptamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, octamethylenediamine, nonamethylenediamine,
5-methylnonamethylenediamine, decamethylenediamine, 1,3-bis (3-aminophenoxy) benzene,
2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis (4-aminophenoxy)
Benzene, bis-4- (4-aminophenoxy) phenylsulfone, bis-4- (3-aminophenoxy) phenylsulfone, 9,9'-bis (4-aminophenyl) fluorene, 2,2-bis (4- Aminophenyl)
Hexafluoropropane or siloxane diamine such as α, ω-bis (3-aminopropyl) polydimethylsiloxane can be used. The above diamines may be used alone or in combination of two or more.

In addition to the tetracarboxylic acid component capable of forming two imide rings after ring closure, a tetracarboxylic acid component selected from tetracarboxylic monoanhydride and tetracarboxylic dianhydride, and a diamine, a molecular weight It is also possible to add a small amount of dicarboxylic acids and dicarboxylic anhydrides such as phthalic acid and phthalic anhydride, or monoamines such as aniline for the purpose of controlling the processability and maintaining processability. Further, various additives such as fillers can be added simultaneously as long as the performance is not impaired.

In the present invention, the synthesis of the polyimide resin is as follows:
0.8 to 1.
The mixture is mixed at a molar ratio of 2: 1 and the mixture is heated and reacted in the range of 80 to 450 [deg.] C. without adding a solvent to form an imidized solvent.
The tetracarboxylic acid component and the diamine used at this time are generally solid, but a solid mixture can be obtained by mixing them in a solid state. Liquid monomers such as silicone diamine also exist, but when these are mixed with a solid tetracarboxylic acid component without adding a solvent in a liquid state, a solid mixture is obtained.

In the present invention, the method of mixing the tetracarboxylic acid component and the diamine is not particularly limited as long as the method can uniformly mix the solid, but a mixer such as a mortar or a high-speed stirring mixer equipped with a heating device is used. It is preferred to use and mix as uniformly as possible. The heat treatment temperature is generally 80 to 450 ° C. and 1 minute to 30 hours is appropriate. However, it is necessary to determine the optimum temperature according to the progress of the reaction depending on the combination of monomers. For example, even if the temperature is gradually increased from a low temperature, or 80 ° C / 30 minutes + 130 ° C
/ 1 hour + 200 ° C./1 hour. The heating temperature is too low (generally 80
If the reaction temperature is lower than 0 ° C.), the reaction rate sharply decreases, unreacted substances remain, and a high molecular weight resin cannot be obtained. In addition, if the heat treatment is performed at a temperature higher than the thermal decomposition temperature of the polymer, undesirable side reactions such as thermal degradation and cross-linking may occur, which may impair the subsequent processability and the physical properties of the resin.

The polyimide resin thus obtained can be pulverized and used as a raw material for molding as it is. In the case of a polyimide resin which is soluble in a solvent, it is dissolved in a solvent and used as a resin varnish. It can be used in the same manner as the polyimide resin varnish.

[0013]

The present invention will be described below in more detail with reference to specific examples, but the present invention is not limited to these examples.

The method and conditions for measuring various properties of the polyimide resin obtained by the present invention are as follows.

(1) Molecular weight distribution Gel permeation chromatography (GPC)
Equipment (Waters high-performance liquid chromatogram,
Polystyrene column GL-S30 manufactured by Hitachi Chemical Co., Ltd.
OMDT-5 type), tetrahydrofuran / N, N-dimethylformamide / phosphoric acid (weight ratio: 1)
00/100/1) as a mobile phase, the absorbance at 270 nm was measured with a Waters type 484 spectrophotometer,
The molecular weight and molecular weight distribution (in terms of polystyrene) were calculated.

(2) Glass transition temperature and melting point Differential scanning calorimeter (DSC220C manufactured by Seiko Instruments Inc.)
At a heating rate of 10 ° C./min in a temperature range of 30 to 500
It was measured under the condition of ° C.

EXAMPLE 1 32.2 g (0.1 mol) of powder of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride and 21.2 g (0.1 mol) of powder of 3,3'-diaminobenzophenone .1 mol) in a mortar for 5 minutes to obtain a solid mixture. This solid mixture is spread evenly on a tray and
Heat treatment was performed at 0 ° C. for 1 hour to obtain a polyimide resin powder.

The glass transition temperature of this polyimide resin powder was 252 ° C., the melting point was 300 ° C., and the weight average molecular weight in terms of polystyrene was 50,000. Further, before and after this heat treatment, the weight decreased by 6.7%, suggesting that almost equimolar monomers reacted (dehydration condensation reaction) as theoretically. The obtained polyimide resin powder is pulverized to a particle size of 1 mm or less by a pulverizer, and a molding temperature of 3 is obtained by an injection molding machine.
When molded at 80 ° C. and a mold temperature of 150 ° C., a good polyimide molded product was obtained.

Example 2 Instead of 32.2 g (0.1 mol) of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride powder,
A polyimide resin powder was obtained in the same apparatus and procedure as in Example 1, except that 34.0 g (0.1 mol) of 3 ', 4,4'-benzophenonetetracarboxylic monoanhydride was used.

The glass transition temperature of this polyimide resin powder was 250 ° C., the melting point was 297 ° C., and the weight average molecular weight in terms of polystyrene was 42,000. Further, the weight was reduced by 9.7% before and after the heat treatment, which suggests that almost equimolar monomers reacted (dehydration condensation reaction) as theoretically. The obtained polyimide resin powder was pulverized to a particle size of 1 mm or less by a pulverizer, and was molded by an injection molding machine at a molding temperature of 380 ° C. and a mold temperature of 150 ° C., whereby a good polyimide molded product was obtained.

Example 3 Instead of 32.2 g (0.1 mol) of powder of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3
3 ', 4,4'-benzophenonetetracarboxylic acid 35.8
Except that g (0.1 mol) was used, a polyimide resin powder was obtained by the same apparatus and procedure as in Example 1.

The glass transition temperature of this polyimide resin powder was 248 ° C., the melting point was 296 ° C., and the weight average molecular weight in terms of polystyrene was 38,000. Further, the weight decreased by 12.3% before and after this heat treatment, which suggests that almost equimolar monomers reacted (dehydration condensation reaction) as theoretically. The obtained polyimide resin powder was pulverized to a particle size of 1 mm or less by a pulverizer, and was molded by an injection molding machine at a molding temperature of 380 ° C. and a mold temperature of 150 ° C., whereby a good polyimide molded product was obtained.

Example 4 Instead of 32.2 g (0.1 mol) of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride powder, a mixture of three kinds of benzophenonetetracarboxylic acid components (3 ,
3.4 g (0.01 mol) of 3 ', 4,4'-benzophenonetetracarboxylic monoanhydride, 3.6 g (0.01 mol) of 3,3', 4,4'-benzophenonetetracarboxylic acid, and A polyimide resin powder was obtained by the same apparatus and procedure as in Example 1 except that 25.8 g (0.08 mol) of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride powder was used. Was.

The glass transition temperature of this polyimide resin powder was 250 ° C., the melting point was 298 ° C., and the weight average molecular weight in terms of polystyrene was 46,000. In addition, the weight decreased by 7.6% before and after the heat treatment, suggesting that almost equimolar monomers reacted (dehydration condensation reaction) as theoretically. The obtained polyimide powder is pulverized by a pulverizer to a particle size of 1 mm or less, and a molding temperature of 38 is obtained by an injection molding machine.
When molded at 0 ° C. and a mold temperature of 150 ° C., a good polyimide molded product was obtained.

Example 5 3,3 ', 4,4'-Benzophenonetetracarboxylic dianhydride powder (32.2 g, 0.1 mol) was mixed with two kinds of diamine (3,3'-diaminobenzophenone) powders. 10.6g
(0.05 mol) and 12.5 g (0.05 mol) of α, ω-bis (3-aminopropyl) dimethyldisiloxane
Was sequentially added and mixed in a mortar to obtain a solid mixture.
The α, ω-bis (3-aminopropyl) dimethyldisiloxane used at this time was liquid in a monomer state, but immediately became a solid mixture when mixed in a mortar. Thereafter, a polyimide resin powder was obtained by the same apparatus and procedure as in Example 1.

The glass transition temperature of this polyimide resin powder was 220 ° C., the melting point was 268 ° C., and the weight average molecular weight in terms of polystyrene was 42,000. Further, the weight decreased by 7.3% before and after the heat treatment, suggesting that almost equimolar monomers reacted (dehydration condensation reaction) as theoretically. To 150 parts by weight of the obtained polyimide resin powder, 350 parts by weight of N-methyl-2-pyrrolidone was added to prepare a polyimide resin solution so that the resin concentration became 30% by weight. Using this resin solution, a stainless steel foil (thickness: 50 μm) which has been subjected to a mold release treatment is applied using a die coater so as to have a thickness of 25 μm after drying, and is continuously coated with 100 μm. ℃ / 3 minutes, 150 ℃
After a heat treatment of 200 ° C. for 3 minutes, the dried coating film was peeled off the stainless steel foil to obtain a polyimide resin film. The obtained polyimide resin film was a film having excellent properties with high flexibility.

Example 6 To 4,4.4 g (0.1 mol) of 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride was added 2,3-bis (4-aminophenyl) hexafluoropropane.
4 g (0.1 mol) was sequentially added and mixed in a mortar to obtain a solid mixture. Thereafter, a polyimide resin powder was obtained by the same apparatus and procedure as in Example 1.

The glass transition temperature of this polyimide resin powder was 322 ° C., the melting point was 366 ° C., and the weight average molecular weight in terms of polystyrene was 43,000. In addition, the weight decreased by 4.6% before and after the heat treatment, suggesting that almost equimolar monomers reacted (dehydration condensation reaction) as theoretically. To 100 parts by weight of the obtained polyimide resin powder, 400 parts by weight of N-methyl-2-pyrrolidone was added to prepare a polyimide resin solution so that the resin concentration became 20% by weight. Using this resin solution, a stainless steel foil (thickness: 50 μm) which has been subjected to a mold release treatment is applied using a die coater so as to have a thickness of 25 μm after drying, and is continuously coated with 100 μm. ℃ / 3 minutes, 150 ℃
After heat treatment at 200 ° C./3 minutes, the dried coating film is peeled off from the stainless steel foil, and the end face of the film is further fixed with a frame, and 250 ° C./3 minutes, 300 ° C./3 minutes, 350 ° C./10
A partial heat treatment was performed to obtain a polyimide resin film. The obtained polyimide resin film was a film having excellent properties with high flexibility and transparency.

Comparative Example 1 Dehydrated and purified N-methyl-2- was placed in a four-necked flask equipped with a dry nitrogen gas inlet tube, a cooler, a thermometer, and a stirrer.
206 g of pyrrolidone was added, and while stirring the system by flowing nitrogen gas, 3,3′-diaminobenzophenone powder 2
Charge 1.2 g (0.1 mol) and stir until uniform. After homogeneously dissolving, while maintaining the system at 20 ° C., a mixture of three benzophenonetetracarboxylic acid components (3,3 ′, 4,4′-benzophenonetetracarboxylic acid) similar to that used in Example 4 3.4 g (0.01 mol) of monoanhydride, 3.6 g (0.01 mol) of 3,3 ', 4,4'-benzophenonetetracarboxylic acid and 3,3', 4,4'-benzophenonetetracarboxylic acid Carboxylic acid dianhydride powder 25.8
g (0.08 mol)), and stirring was continued for 8 hours. During this time, the flask was kept at 20 ° C. afterwards,
The nitrogen gas introduction tube and the condenser were removed, a Dean-Stark tube filled with toluene was attached to the flask, and 100 g of toluene was added to the system. The system was heated to 175 ° C. in place of the oil bath, and the generated water was removed from the system. After heating for 6 hours, generation of water from the system was no longer observed. A polyimide resin solution was obtained by cooling the system.

When the molecular weight of this resin was measured, the weight average molecular weight was 8,000. Using this resin solution, the thickness after drying was 25 μm on the release surface of a stainless steel foil (thickness: 50 μm) that had been subjected to a release treatment in the same manner as in Example 5.
m and then continuously heated at 100 ° C./3 minutes, 150 ° C./3 minutes, 200 ° C./3 minutes, and then tried to peel the dried coating film from the stainless steel foil. However, because of the low molecular weight, the film was fragile and crushed, and a polyimide resin film could not be obtained.

[0031]

According to the method of the present invention, not only the conventional high-purity tetracarboxylic dianhydride, but also the tetracarboxylic acid or tetracarboxylic acid which is a ring-opened product contained therein as an impurity is contained. Anhydride can be used as a starting monomer. Furthermore, a polyimide resin can be easily obtained by a very simple process without using an expensive organic polar solvent which is difficult to control and harmful. Therefore, the method of the present invention is an industrially suitable method for producing a polyimide resin which is extremely superior to a conventional method for synthesizing a polyimide resin via a polyamic acid using a solvent.

Claims (2)

[Claims] 1. One or two members selected from the group consisting of tetracarboxylic acids, tetracarboxylic monoanhydrides, and tetracarboxylic dianhydrides capable of forming two imide rings after ring closure.
A method for producing a polyimide resin, comprising mixing at least one or more kinds of tetracarboxylic acid components and a diamine without using a solvent, and then performing a heat treatment. 2. The tetracarboxylic acid component and the diamine are mixed at a molar ratio of 0.8 to 1.2: 1, and heat treatment is performed for 8 hours.
The method according to claim 1, wherein the heating is performed at a temperature of 0 to 450C.
3. The method for producing a polyimide resin according to item 1.