JPH07150038A - Molding polyimide resin powder composition - Google Patents

Abstract

PURPOSE:To form molding polyimide resin powder into a molding without causing any crack by improving the fluidity and operating efficiency during the molding and further the uniformity in density of the molding. CONSTITUTION:This molding polyimide resin powder composition is obtained by adding 0.05-3wt.% powdery silica aerogel having 25-210 Angstrom pore diameter and 60-800ml/g pore volume to polyimide resin powder. The resultant composition is then thermally compression molded to afford a molding composition. Since the prescribed aerogel adsorbs the moisture on the surface of the polyimide resin powder to prevent the resin powder from being electrified, molding powder having high fluidity without causing stickiness and static electricity is obtained. The resultant powder is further used to provide a molding without any crack.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding polyimide resin powder composition and a molding composition thereof.

[0002]

2. Description of the Related Art Polyimide resins have excellent electrical characteristics,
It is widely used as a functional plastic that utilizes heat resistance, but its extremely high softening point makes it difficult to perform melt molding such as injection molding, which is widely adopted for general synthetic resins, and compression molding and ram extrusion. It is known to be molded by molding.

In these molding methods, a molding polyimide resin powder as a so-called molding powder is pressed, compressed and fired. However, in order to improve the adhesion between the powders, small particles should be used as much as possible. It is preferable to use a powder having a diameter. Here, the specific gravity of the polyimide resin powder is
It is relatively small, around 1.4, and the particle size of the powder used is as small as about 10 μm, so it is extremely light and easily scattered, and handling during molding is difficult.

As an attempt to improve such a handling defect of the polyimide resin powder, Japanese Patent Publication No. 52-3287.
Japanese Patent Publication 7 discloses a method of suppressing the scattering of dust by adding polytetrafluoroethylene.

[0005]

However, the molding polyimide resin powder not only easily scatters, but also sticks to the container or mold by being charged with static electricity in a dry state, and when it absorbs moisture, it becomes sticky and has poor flowability. There is a problem that is bad.

When the mold is filled with the polyimide resin powder having poor flowability as described above, the amount of the powder filled becomes uneven depending on the pressing direction, that is, the density of the molded product is partially different. There is also a problem that cracks and voids are generated after heat molding.

Therefore, the present invention solves the above-mentioned problems, improves the fluidity of the molding polyimide resin powder, makes it easier to handle during molding, and keeps the density of the molded product uniform. It is an object of the present invention to obtain a molded product of stable quality without the occurrence of

[0008]

In order to solve the above problems, in the present invention, a powdery silica aerogel having a pore diameter of 25 to 210Å and a pore volume of 60 to 800 ml / g is added to a polyimide resin powder in an amount of 0. The amount of 05 to 3% by weight was added to obtain a molding polyimide resin powder composition.

Further, the above-mentioned molding polyimide resin powder composition is molded by heating and compression to obtain a molding composition. The details will be described below.

First, the polyimide resin powder used in the present invention may be either thermosetting polyimide or thermoplastic polyimide, and conventionally known molding powders that can be extrusion-molded and compression-molded can be used without limitation. As described above, the polyimide resin resin powder as the molding powder has a specific gravity of about 1.4 and an average particle diameter of about 10 μm. Examples of commercially available polyimide resin powders include Upyrex (registered trademark), Mitsui Toatsu Chemicals Inc .: Aurum (registered trademark) manufactured by Ube Industries, Ltd., or polyimide P84 manufactured by LENZING AG of Austria represented by the following chemical formula 1. Can be mentioned as a representative example.

[0011]

[Chemical 1]

The powdery silica aerogel used in the present invention is an aerogel containing silicon dioxide, which is extremely porous, as a main component, and has a pore diameter of 25 to 210Å,
It has a pore volume of 60 to 800 ml / g and is extremely porous.

If the pore diameter or the pore volume is out of the above-mentioned range, the stickiness and the antistatic property of the polyimide resin powder are not sufficient, and the intended effect of improving the powder fluidity of the present invention is achieved. I can't. Further, the powder particle size of silica airgel has an average particle size of 1.5 to 15
When it is in the range of μm, it is easy to mix uniformly, and a favorable result can be obtained for the effect of improving the powder fluidity.

Such silica aerosol can be produced by applying a method of heating jelly-like silica gel (SiO ₂ .nH ₂ O) to a temperature above the critical temperature of the liquid contained in the gel. Of the commercially available silica airgel,
As a material satisfying the above-described porosity condition, there is Sylysia (registered trademark) manufactured by Fuji Silysia Chemical Ltd.

The ratio of such powdery silica airgel mixed with the polyimide resin powder is 0.05 to 3% by weight. This is because it is difficult to obtain the desired effect of improving the fluidity in a small amount less than the above range, and when compounded in a large amount exceeding the above range, the physical properties of silica adversely affect the physical properties of the polyimide resin molded article. .

When mixing the above-mentioned components, a general-purpose mixer such as a Henschel mixer, a ball mixer, a ribbon blender or a V type blender can be used.

The polyimide resin powder may be mixed in the form of primary particles, or powdery silica aerogel may be added to the granulated secondary particles. Further, addition of a solid lubricant or other modifier such as graphite, molybdenum disulfide or tetrafluoroethylene powder to the polyimide resin powder so as to improve the slidability of the molded body also impairs the effects of the present invention. There is nothing to do.

[0018]

The molding polyimide resin powder composition of the present invention has a feature that the added porous silica airgel absorbs moisture on the surface of the polyimide resin powder, so that the molding powder is not sticky and the polyimide resin powder is in a dry state. When mixed in, because it absorbs moisture contained in the air and exhibits conductivity, the chargeability of the polyimide resin powder is alleviated and the fluidity becomes a high-quality molding polyimide resin powder with better flowability. .

When such a molding polyimide resin powder is filled in a mold, the fluidity is good, so that the powder filling amount becomes uniform depending on the pressurizing direction, that is, the density of the molded product becomes uniform, and it is heated and compressed. A molded product without cracks and voids after molding.

[0020]

【Example】

[Examples 1 and 2, Comparative Examples 1 and 2] Polyimide resin powder represented by the formula (1) (LENZIN, Austria)
Polyimide P84 manufactured by GAG Co., Ltd. is used as a silica aerogel satisfying a predetermined porosity in 2 kg of Silicia 350 manufactured by Fuji Silysia Chemical Ltd. (hereinafter referred to as silica aerogel-1), or a conventional general-purpose silica aerogel. Aerogel 200 (hereinafter referred to as silica airgel-2) manufactured by Nippon Aerosil Co., Ltd. as non-porous) is shown in Table 1.
Were mixed in a Henschel mixer and mixed at a rotation speed of 500 rpm for about 10 minutes to obtain a molding polyimide resin powder composition.

The resulting molding powder was examined for fluidity and the presence of cracks by the following test method, and the results are also shown in Table 1.

(A) Flowability test 30 g of the molding powder was placed on a vibrating # 10 mesh standard sieve, and the molding powder that spontaneously dropped through the sieve mesh was piled up in a mountain shape, and the slope and floor of the mountain were piled up. The angle of repose θ (maximum inclination that does not collapse) of the surface was measured by a measuring machine (manufactured by Tsutsui Rikagaku Kikai Co., Ltd.), and the results are shown in Table 1. That is, the angle of repose θ is
The larger the fluidity of the powder, the larger the value.

The molding powder (g) remaining on the sieve was weighed and evaluated as the fluidity of the molding powder in terms of the ease of passing through the sieve. That is, it can be said that the smaller the remaining amount, the better the fluidity of the molding powder.

(B) Presence or absence of cracks The obtained molding powder is used to mold a mold (inner diameter 30
mm, outer diameter 60 mm, length 150 mm), the mold temperature was 345 ° C., the molding pressure was 1000 kgf / cm ² , and the material was held for 20 minutes and then cooled, and the inner diameter was 30 mm, the outer diameter was 60 mm, and the length was 30 mm. 5 disk-shaped molded body test pieces
Individually manufactured.

Each of the molded test pieces was cut in half in the axial direction and the cross section was observed to check for cracks. The results (number of test pieces having cracks / 5) are also shown in Table 1. did.

[0026]

[Table 1]

As is clear from the results in Table 1, Comparative Examples 1 and 2 in which the predetermined silica airgel was not compounded
Has a large remaining amount on the sieve of 1.0 to 1.3 g and an angle of repose of 6
It was as large as 0 to 65 degrees, that is, poor in fluidity, and cracks were observed inside (cross section) of the molded test piece.

On the other hand, in Examples 1 and 2 in which silica airgel having a predetermined porosity was blended, the residual amount on the sieve was 0.1 to 0.2 g, which was 1/6 to 1 of the comparative example. It was as low as / 10, the angle of repose was as small as 40 to 45 degrees and excellent in fluidity, and no cracks were observed in the molded product.

[0029]

As described above, according to the present invention, since the silica airgel having a predetermined porosity added to the polyimide resin powder adsorbs moisture on the surface of the polyimide resin powder and prevents charging, there is no stickiness. It becomes a polyimide resin powder for molding that has high fluidity and does not generate static electricity, and is easy to handle during molding and productivity is improved. Further, the molded product has an advantage that the internal density is uniform and the quality is stable with no cracks.

Claims (2)

[Claims] 1. A polyimide resin powder having a pore size of 25 to 2
A molding polyimide resin powder composition obtained by adding 0.05 to 3% by weight of powdery silica airgel having a pore volume of 60 to 800 ml / g. 2. A molded body composition obtained by molding the molding polyimide resin powder according to claim 1 by heat compression.