JPH04201435A - Preparation of molded item made of polyimide resin - Google Patents

Abstract

PURPOSE:To remove occurrence of defects such as cracks, neckings and strain in a molded item even when high pressure is applied by performing compression molding of a polyimide resin compd. under a vibration applied by means of a vibration-applying apparatus when a polyimide resin compd. consisting of a polyimide resin or a polyimide resin and a filler is compression-molded in a mold and then, it is calcined to prepare the molded item. CONSTITUTION:As a polyimide resin, a resin having a polyimide structure of formula is mainly used. As a filler, a fibrous material such as glass fiber, carbon fiber, asbestos and inorg. whiskers, talc, silica, alumina, kaolin, wollastonite, glass bead, ceramic powder, carbon powder, graphite, molybdenum disulfide, calcium carbonate etc., can be cited. The amt. of loading is pref. 10-60wt.% to the sum of the polyimide resin and the filler. As a method for applying vibration during compression molding, a vibration molding machine, such as a multi-purpose vibration molding press is pref. used and the number of vibration is pref. 3kHz.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a polyimide resin molded product that has high strength and does not suffer from defects such as cracks, constrictions, and distortions in the molded product.

[Conventional technology]

Polyimide resin is a resin with extremely excellent heat resistance, but
Its softening point is so high that normal melt molding is impossible.

Therefore, conventionally, to mold polyimide resin, a mold is filled with polyimide resin powder or a resin compound with an inorganic filler added thereto, and a pressurizing device such as a hydraulic press, pneumatic press, or mechanical press is used to mold the polyimide resin. A green compact is formed by applying pressure using a
A compression firing molding method is used in which a polyimide resin molded product is obtained by heating and firing at a high temperature of about 0°C.

[Problem to be solved by the invention]

In order to obtain a high-strength molded product by compressing and firing polyimide resin, it is necessary to apply a pressure of approximately 3000 kg/Cl112.The higher the pressure, the stronger the molded product can be obtained, but if the pressure is applied above a certain pressure. This has the disadvantage that cranks occur on the surface of the green compact, especially on the sides, that it becomes constricted during firing, or that it becomes distorted and cracked, resulting in loss of commercial value.

This defect in the molded product does not occur if the compression pressure is lowered, but there is a problem in that the strength of the molded product decreases when the pressure is low.

The cause of the defects is thought to be uneven pressure during compression, and one possible way to prevent this is to add graphite or the like to improve the fluidity of the powder, but this has not been sufficient.

An object of the present invention is to provide a method for producing a molded product that does not suffer from cracks, constrictions, distortions, or other defects even when high pressure is applied when polyimide resin or a blend of polyimide resin and filler is compressed and fired. There is a particular thing.

[Means to solve the problem]

In order to solve the problems of the prior art described above, the present invention takes the following measures.

That is, the method for producing a polyimide resin molded article of the present invention involves compression molding a polyimide resin or a polyimide resin compound consisting of a polyimide resin and a filler in a mold, and then firing it to produce a molded article. The method is characterized in that it is carried out under vibration using a vibration device.

The polyimide resin used in the present invention mainly has the following polyimide structure.

The second polyimide resin is usually made by reacting pyromellitic anhydride with diaminodiphenyl ether.
A copolymer in which a part of the acid component or diamine component is replaced with another acid or diamine component, or a resin mixture formed by partially mixing a polyimide resin with another molecular structure can also be used, but the resin with the above polyimide structure can also be used. is optimal.

On the other hand, various fillers can be added to the polyimide resin of the present invention for the purpose of imparting moldability, dimensional stability, low water absorption, etc.

Preferred fillers include glass fiber, carbon fiber, asbestos, fibrous materials such as inorganic whiskers, talc, silica,
Alumina, kaolin, wollastenite, glass peas,
Examples include ceramic powder, carbon powder, graphite, molybdenum disulfide, calcium carbonate, etc., and the amount of these added is 1% to the total amount of polyimide resin and filler.
0 to 60% by weight is preferred.

Furthermore, as the amount of filler added increases, cracks are more likely to occur in the molded product, but if it is less than 60% by weight, it is possible to prevent the occurrence of cracks and the like by applying vibration during compression.

In the present invention, as a method of vibrating compression molding, it is possible to attach a separate vibration device to the compressor, but it is preferable to use a vibration molding machine, such as a multipurpose vibration molding press (
(manufactured by Asahi Engineering Co., Ltd.), etc. can be used. The frequency used in the present invention is 3 KFl
z is preferred.

In the molding method of the present invention, polyimide resin powder is compressed while being vibrated to form a green compact, which is then heated and fired, but the pressure for making the green compact is 2000 to 5000.
kg/cm" is preferable, and the firing temperature is 370 to 43
0°C is preferred.

〔Example〕

The present invention will be specifically described below with reference to Examples.

Example 1 "T" made of polyimide resin (Toshishiku Co., Ltd.) produced by reacting pyromellitic anhydride and 4,4'-diaminodiphenyl ether in a mold with an inner diameter of 50 mm and a height of 300 mm.
160g of granular powder (1-3000") was added, and a pressure of 60 tons was applied at room temperature to create a mold with a diameter of 50mm and a height of 6.
A round bar green compact of 0IIIl is molded. At this time, the compact was molded under vibration using a multi-purpose vibration molding press manufactured by Asahi Engineering Co., Ltd.

This press is a molding machine that applies pressure while applying a high-frequency cross vibration effect, and the high-frequency cross vibration causes material particles to flow and align, resulting in a molded product with uniform packing density. Thereafter, the green compact was fired, but the green compact did not crack.

Comparative Example 1 In the process of molding a green compact in the same way as in Example 1 using the same mold and the same material, a Toho Press press was used as the molding press, and 100 tons was produced without vibration.
A round bar green compact with a diameter of 5 mm and a height of 60 mm+ was molded at a pressure of . When this was placed in a kiln and fired, the molded product cracked in the center.

Example 2 and Comparative Example 2 Polyimide resin (Toshishiku Co., Ltd. “Tl-3000”) was placed in a 100mIw x 100mm x 300mm mold.
After adding 700g of granular powder and heating to 150°C,
Applying 100 tons of pressure, 100mm x 100
A green compact measuring 50 mm x 50 mm was molded.

At this time, a 100 ton press manufactured by Toho Press Co., Ltd.
A hydraulic press was used (Comparative Example 2).

On the other hand, a 7Qton was pressed in the same manner using a multipurpose vibration molding press manufactured by Asahi Engineering Co.
It was molded under vibration at a pressure of (Example 2).

These green compacts were placed in a kiln and fired, but the example using a vibration forming press did not crack, but the one formed using a non-vibrating hydraulic press (Comparative Example 2) had a height of 25 mm. There was a crack in the area.

〔Effect of the invention〕

In the present invention, when polyimide is compression molded, a compacted powder is obtained by compressing it under vibration, so there is no unevenness in the pressure of the powder, and cracks and cranks are prevented from forming in the molded product. .

Agent: Patent Attorney Nobuo Kogawa -

Claims (1)

[Claims] A polyimide resin or a polyimide resin compound consisting of a polyimide resin and a filler is compression molded in a mold, and then
1. A method for producing a polyimide resin molded article, which comprises performing compression molding under vibration using a vibrator when producing the molded article by firing.