JP2000191782A - Production of polyimide powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject fine powder in good productivity without mechanically pulverizing by polymerizing a lower alcohol half esterification product of an aromatic tetracarboxylic dianhydride with an aromatic diamine in a solvent. SOLUTION: (A) A lower alcohol half esterification product of an aromatic tetracarboxylic dianhydride is polymerized with (B) an aromatic diamine in (95:100) to (100:95) molar ratio of the component A/the component B in (C) a solvent (e.g. N-methyl-2-pyrrolidone) at a solid content concentration of preferably 20-60 wt.%, more preferably 30-40 wt.% to provide the objective powder. The component A is obtained by subjecting (i) an aromatic tetracarboxylic dianhydride (e.g. 3,3',4,4'-biphenyltetracarboxylic dianhydride) to half esterification with (ii) a lower alcohol, preferably a 1-5C aliphatic alcohol (e.g. methanol) in an amount of 2-3 mol based on 1 mol component (i).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyimide powder, and more particularly to a method for producing a polyimide powder in which an aromatic tetracarboxylic acid ester is reacted with an aromatic diamine. The present invention relates to a method for producing a highly productive polyimide powder which can contain a polyimide powder and hardly causes aggregation of the powder.

[0002]

2. Description of the Related Art Hitherto, polyimide powder has been produced by reacting aromatic tetracarboxylic dianhydride with an aromatic diamine in a solvent. For example, JP-A-61-2522
No. 8 describes a method for precipitating nitrogen-containing heat-resistant polymer particles such as polyimide powder.
No. 2 (Japanese Patent Publication No. 2-48571),
In JP-A-200453 and the like, a 3,3 ′, 4,4′-biphenyltetracarboxylic acid component and an aromatic diamine component are polymerized and imidized in N-methyl-2-pyrrolidone at a temperature of 155 ° C. or less. After that, the temperature was raised to 160 to 300 ° C. in a short time to complete the imidization, and the imidization ratio was 95% or more to precipitate aromatic polyimide powder as fine particles,
There is described an example in which a polyimide powder having a logarithmic viscosity of 0.2-1 and an average particle size of 3 to 20 μ was prepared by collecting the polyimide powder from a reaction mixture by filtration.

[0003] However, in the method for producing polyimide powder described in the above-mentioned known documents, it is necessary to reduce the size by adding operations such as grinding the polyimide powder, or a solution of polyamic acid for producing polyimide. It is necessary to keep the polyamic acid concentration in the solution to less than 20% by weight. If the polyamic acid concentration is increased, the reaction system may gel during imidization, and the desired polyimide powder may not be obtained.

For this reason, polyamic acid powder (aggregate)
There is also an attempt to obtain a polyimide powder by once taking out, heating, drying and pulverizing. However, it has been pointed out that it is difficult to control the temperature at the time of heating the polyamic acid powder aggregate, and it is not practical because metal impurities are easily mixed into the polyamic acid powder. Therefore, according to the conventional technology, it was not possible to produce fine polyimide powder with high productivity without going through complicated steps such as a pulverizing step.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to produce a fine polyimide powder with high productivity without mechanical pulverization using a conventionally known aromatic tetracarboxylic acid component and an aromatic diamine as starting materials. To provide a method for producing polyimide powder.

[0006]

That is, the present invention provides:
The present invention relates to a method for producing a polyimide powder, comprising polymerizing a lower alcohol half-esterified aromatic tetracarboxylic dianhydride and an aromatic diamine in a solvent.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be listed below. 1) The solid content is 20-60% by weight, especially 30-4% by weight.
The method for producing the polyimide powder described above, which is 0% by weight. 2) The method for producing the above polyimide powder, wherein the lower alcohol is an aliphatic alcohol having 1 to 5 carbon atoms. 3) When the aromatic tetracarboxylic dianhydride is 3,3 ′,
The method for producing the above polyimide powder, which is 4,4′-biphenyltetracarboxylic dianhydride. 4) The method for producing the above polyimide powder, wherein the aromatic diamine is p-phenylenediamine or 4,4′-diaminodiphenyl ether.

[0008] Examples of the aromatic tetracarboxylic dianhydride in the present invention include 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride. Some of these, preferably 50 mol% or less, especially 20 mol% or less, may contain other aromatic tetracarboxylic dianhydrides such as 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride or 2 , 2'-bis (3,4
Dianhydride of -dicarboxyphenyl) propane, dianhydride of bis (3,4-dicarboxyphenyl) methane,
It may be replaced by dianhydride of (3,4-dicarboxyphenyl) ether.

In the present invention, the aromatic tetracarboxylic dianhydride is converted to a lower alcohol, preferably an aliphatic alcohol having 1 to 5 carbon atoms, for example, methanol, ethanol, propanol, or the like. It is necessary to use those which are half-esterified with methanol, especially butanol. The amount of the lower alcohol used for the half esterification is preferably 2-3 mol per 1 mol of the aromatic tetracarboxylic dianhydride. In addition, the above-mentioned hardware
The esterification is preferably performed in a solvent used for the polymerization.

[0010] The aromatic diamine in the present invention is not particularly limited, but p-phenylenediamine, 4,4
4'-Diaminodiphenyl ether is preferably used. Some, preferably up to 50 mol%, especially up to 20 mol%, may be replaced by other aromatic diamines. The other aromatic diamine is not particularly limited, but 4,4 ′
-Diaminodiphenylmethane, 2,2-bis [4- (4
-Aminophenoxy) phenyl] propane, metaphenylenediamine, 4,4'-diaminodiphenylpropane, 1,4-bis (4-amino-phenoxy) benzene, 1,3-bis (4-amino-phenoxy) benzene, etc. Can be mentioned.

In the present invention, the aromatic tetracarboxylic acid component (half ester of aromatic tetracarboxylic dianhydride) and the diamine component are 95: 100-100: 9.
It is preferred to use a molar ratio of 5, especially 98: 100-100: 98.

In the method of the present invention, the above aromatic tetracarboxylic dianhydride and lower alcohol are preferably added to a reaction solvent in the presence of an inert gas, and the reaction is allowed to proceed. After half-esterifying the acid dianhydride and adding an aromatic diamine to the resulting solution, and precipitating fine particles at a temperature of about 140 ° C. or more and 180 ° C. or less, preferably under total reflux conditions, The reaction is continued at a temperature within the range of about 220 ° C. for 0.2 to 20 hours, and the logarithmic viscosity (30 ° C., 0.5 g / 100 ml concentrated sulfuric acid) becomes 0.2
In particular, it is preferable to obtain a polyimide powder having an imidation ratio of 95% or more and an average particle size of about 5 to 25 μm and a small amount of aggregates.

Prior to the step of depositing the fine particles, the temperature of the reaction solution is adjusted, and then an imidization catalyst, preferably an imidazole-based imidization catalyst, is added to the reaction system and imidization is performed under the above-mentioned heating conditions. May adjust the imidation rate. As the imidation catalyst, for example, imidazo-
And imidazole compounds such as 2-methylimidazole, 1,2-dimethylimidazole and 2-phenylimidazole.

Examples of the solvent include amide solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide and N-methylcaprolactam. -Pyrrolidone is preferably used.

The method of obtaining the polyimide powder after the completion of the imidation reaction is not particularly limited. For example, after the reaction mixture is cooled as it is or to room temperature, the aromatic polyimide powder is separated by filtration and the powder is dissolved in a solvent. Wash with
A drying method can be adopted. As the washing solvent, any solvent having a low boiling point which can be substituted for the reaction solvent may be used, and water, ethanol, acetone and the like are preferable. Drying is carried out under normal pressure or reduced pressure of 250 ° C. or less, preferably at 200 ° C. or less, preferably at 350 ° C. for 1 hour, and the weight loss rate is 2% or less, particularly 1.5% or less. It is preferable that Since the polyimide powder of the present invention is hardly agglomerated, pulverization is not required.

[0016]

Embodiments of the present invention will be described below.

EXAMPLE 1 N-methyl-2-pyrrolidone (NMP) 285 was used as a reaction solvent in a 500-ml cylindrical flask equipped with a stirrer, a reflux condenser (with a water separator), a thermometer, and a nitrogen inlet tube.
g, 90 g (0.31 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) and 20.6 g (0.64 mol) of methanol, The mixture was heated and stirred at 80 ° C. for 1 hour. After completion of the reaction, the reaction solution was cooled to 50 ° C., and 61.3 g (0.31 mol) of 4,4′-diaminodiphenyl ether was dissolved under stirring over 3 hours. The temperature of the reaction solution was raised in an oil bath at 200 ° C., and an imidization reaction was carried out for a time to precipitate a polyimide powder. The precipitated polyimide powder was separated by filtration, washed with hot water and dried in vacuum. Using a super-centrifugal automatic particle size distribution analyzer (CAPA-700 type) manufactured by Horiba, Ltd., 0.05 g of the polyimide powder was ultrasonically dispersed in 50 g of ethylene glycol (for 20 minutes). Was 15 μm.
According to the electron micrograph of the obtained polyimide powder, no aggregation was observed. This polyimide powder could be directly molded into a molded body by a conventional method.

Example 2 In the same apparatus as in Example 1, N-methyl-2 was used as a reaction solvent.
-Pyrrolidone (285 g) and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) 9
0 g (0.31 mol) and methanol 20.6 g (0.6
4 mol) and heated and stirred at 80 ° C. for 1 hour. After completion of the reaction, the reaction solution was cooled to 50 ° C., and 61.3 g of 4,4′-diaminodiphenyl ether (ODA) (0.3%) was added.
1 mol) was dissolved under stirring over 3 hours. The temperature of the reaction solution was raised in an oil bath at 200 ° C. to perform an imidization reaction, thereby precipitating polyimide powder. The precipitated polyimide powder was separated by filtration, washed with hot water and dried in vacuum. The particle diameter of this polyimide powder was measured in the same manner as in Example 1, and it was 18 μm. According to the electron micrograph of the obtained polyimide powder, no aggregation was observed. This polyimide powder could be directly molded into a molded body by a conventional method.

Comparative Example 1 The same apparatus as in Example 1 was used except that N-methyl-2-
Add 343 g of pyrrolidone, heat to 85 ° C.,
50 g (0.17 mol) of 3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added, and the mixture was heated at 80 ° C. for 1 hour.
Stirred. Then, 4,4'-diaminodiphenyl-
34.0 g (0.17 mol) of Teru and 3.1 g (0.1
7 mol), and the temperature of the reaction solution was raised in an oil bath at 200 ° C. to cause an imidization reaction to precipitate polyimide powder. The precipitated polyimide powder was separated by filtration, washed with hot water and dried in vacuum. The particle size of this polyimide powder was measured in the same manner as in Example 1, and it was 7 μm. Also, according to the electron micrograph of the obtained polyimide powder, agglomeration of a large number of particles was observed, and the size of one agglomerate was large, about 100 μm, and it was impossible to mold it into a compact as it was. Grinding was required.

Comparative Example 2 In the same apparatus as in Example 1, N-methyl-2-
Add 343 g of pyrrolidone, heat to 85 ° C.,
90 g (0.31 mol) of 3 ', 4,4'-biphenyltetracarboxylic dianhydride was added and stirred. Then
61.3 g of 4,4'-diaminodiphenyl ether
(0.31 mol) and 5.5 g (0.31 mol) of water were added, and the temperature of the reaction solution was raised in a 200 ° C. oil bath to carry out an imidization reaction to precipitate polyimide powder. The precipitated polyimide powder was separated by filtration, washed with hot water and dried in vacuum. The particle size of this polyimide powder was measured in the same manner as in Example 1, and found to be 10 μm. In addition, according to the electron micrograph of the obtained polyimide powder, aggregation of a large number of particles was observed, and the size of one aggregate was large and about several 100 μm, and it was impossible to form a molded body as it was. Yes, crushing was required.

Comparative Example 3 The same apparatus as in Example 1 was used except that N-methyl-2-
Add 343 g of pyrrolidone, heat to 85 ° C.,
90 g (0.31 mol) of 3 ', 4,4'-biphenyltetracarboxylic dianhydride was added and stirred. Next, 33.1 g (0.31 mol) of paraphenylenediamine and 5.5 g (0.31 mol) of water were added.
The temperature was raised in an oil bath at ℃ to carry out an imidization reaction.
At the same time as the precipitation of the polyimide powder, the whole inside of the container was solidified, and the polyimide powder could not be obtained.

[0022]

Since the present invention has the structure described in detail above, it has the following effects.

That is, according to the method of the present invention, fine polyimide powder can be produced with high productivity without mechanical pulverization.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F070 AA55 DA33 4J043 PA02 QB24 RA34 SA06 SB01 TA11 TA12 TA31 TA32 TB01 UA121 UA131 UA132 UB121 VA041 XA16 ZB05

Claims (5)

[Claims] 1. A process for producing a polyimide powder, comprising polymerizing a lower alcohol half-esterified aromatic tetracarboxylic dianhydride and an aromatic diamine in a solvent. 2. The process for producing a polyimide powder according to claim 1, wherein the solid content is 20 to 60% by weight. 3. The method according to claim 1, wherein the lower alcohol is an aliphatic alcohol having 1 to 5 carbon atoms. 4. The method according to claim 1, wherein the aromatic tetracarboxylic dianhydride is 3,3.
The method for producing a polyimide powder according to claim 1, which is 3 ', 4,4'-biphenyltetracarboxylic dianhydride. 5. The method according to claim 1, wherein the aromatic diamine is p-phenylenediamine or 4,4′-diaminodiphenyl ether.