JPH05178665A - Production of hollow graphite molded material - Google Patents

Abstract

PURPOSE:To easily obtain a hollow graphite molded material easy for handling, excellent in lubricity and electrical conductivity without necessity of complicated manufacturing processes. CONSTITUTION:A particulate material of a thermoplastic resin such as polyethylene is arranged in a graphite powder and is heat-treated. The heat treating is executed to carbonize the thermoplastic resin, here, the surface of the thermoplastic resin is once melted and is carbonized. For example, in the case of polyethylene, after unmolten treatment in an oxidizing atmosphere at a relatively low temp., carbonization is executed in a non-oxidizing atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hollow graphite molded product used for a solid lubricant required to have heat resistance, chemical resistance and lubricity, a conductive filler for improving conductivity, and the like.

[0002]

BACKGROUND ART Graphite powder has excellent heat resistance and chemical resistance,
Among them, natural graphite is used as a solid lubricant or a conductive filler because it has excellent crystallinity, but since it is a fine and lightweight powder, it is difficult to handle and causes dust pollution. It is also becoming.

On the other hand, in order to improve the handleability of the graphite powder, a method of surface-treating the graphite powder with a synthetic resin, a wax, a metal or the like, a manufacturing method of adding a binder to form a granule or the like are known. ing.

[0004]

Although the graphite powder surface-treated with another substance is certainly easy to handle, the graphite itself is not exposed on the surface, and therefore the lubricating property which is the original property of graphite Inferior in properties and conductivity. Also,
In the case of a graphite powder in which a binder is added to form a granule, the binder covers much of the graphite surface, and thus the lubricity is inferior. Further, both require complicated manufacturing processes such as surface treatment, kneading, molding, crushing, granulation and heat treatment.

Therefore, the present invention provides a method for producing a hollow graphite molded product which is easy to handle and does not deteriorate the properties such as the original lubricity and conductivity of graphite without requiring a complicated production process. The purpose is to do.

[0006]

The present invention uses a particulate material of a thermoplastic resin and graphite powder, and after the particulate material is placed in the graphite powder, the surface of the particulate material is once melted. The gist is a method for producing a hollow graphite molded product having a large amount of carbide inside and a large amount of graphite powder outside, which is characterized by post-carbonization.

The details will be described below. The thermoplastic resin particulate matter used in the present invention has a carbon yield of 1 to 1 upon heat treatment.
It is preferably about 0%, and examples thereof include various materials such as polyethylene, polypropylene, polystyrene, nylon, polyvinyl chloride, and polyvinyl acetate. Since the carbon yield varies depending on the heat treatment method, the heat treatment method may be appropriately changed depending on the type of the thermoplastic resin. For example, polyethylene, polypropylene, polystyrene, nylon, etc. have a carbon yield of about 1 to 10% when subjected to infusibilizing treatment in an oxidizing atmosphere and then carbonizing treatment in a non-oxidizing atmosphere. Since the carbon yield of vinyl acetate and the like increases further when subjected to the same heat treatment, it is preferable to perform heat treatment in a non-oxidizing atmosphere without performing infusibilizing treatment in an oxidizing atmosphere. The particle size of the particulate matter depends on the degree of carbon yield,
If it is too large, it will be difficult to maintain the shape of the obtained hollow graphite molded product. Further, since it is difficult to mold unless the particle diameter of the graphite powder used is very different, the particle diameter of the graphite powder is preferably 5 times or more. Among the above-mentioned substances, polyethylene includes spherical and granular materials having various particle diameters of several μm to more than 1000 μm, which makes it easy to set the size and shape of the hollow graphite molded product to be obtained, It is particularly preferable because it hardly changes. When a substance other than polyethylene is used, the shape may change slightly.

As the graphite powder, any of natural graphite such as flake graphite, flake graphite and soil graphite, and artificial graphite can be used, and the intended use of the hollow graphite molded product and the particle size of the above particulate matter. In consideration of the above, the properties and particle size of the graphite powder may be appropriately selected. The above-mentioned particulate matter is arranged in this graphite powder. In this case, it is sufficient if the graphite powder exists in a thickness equal to or greater than the wall thickness of the hollow graphite molded product to be obtained around the particulate matter. ..

As described above, in the heat treatment, depending on the type of particulate matter, the infusibilizing treatment is performed by raising the temperature from room temperature to 250 to 350 ° C. in an oxidizing atmosphere such as air or oxygen, and then the particulate matter is removed. When firing is performed in a non-oxidizing atmosphere such as in an inert gas such as nitrogen or argon or in a vacuum up to the temperature of carbonization, or when firing is performed directly in a non-oxidizing atmosphere without infusibilizing treatment in an oxidizing atmosphere. It is divided into the case of applying. When the particulate material of the thermoplastic resin is used, this baking treatment is generally sufficient at about several hundreds of degrees Celsius, but in order to graphitize the carbonized particulate material,
You may give a processing of 000-3000 degreeC. If all of the hollow graphite moldings are made of graphite, lubricity and conductivity will be further improved. After the heat treatment, the excess graphite powder is removed by sieving to obtain a hollow graphite molded product.

Although the mechanism by which the hollow graphite molded product is formed is not clear, the surface of the particulate matter of the thermoplastic resin placed in the graphite powder is once melted by heat treatment and becomes fluid, and It is considered that the graphite powder particles are adhered one after another, and then the particulate matter remains as a carbide to function as a binder to form a hollow graphite molded product.

The hollow graphite molded product can be used as it is for a solid lubricant or a conductive filler having good handleability. However, by filling the hollow portion with another substance, the performance is improved or another function is added. Can be planned. For example, if the hollow part is filled with lubricating oil, it becomes a solid lubricant plus liquid lubricant material, which can improve the lubricity and expand the range of use. It can also be. Further, by filling with a binder resin, it becomes a material for a graphite molded body which can be easily manufactured by firing after pressure molding. here,
As a method of filling the hollow portion with another substance, a general method such as immersing the hollow graphite molded product in a solution containing the substance to be filled can be used.

The hollow graphite molded product produced according to the present invention has a large amount of carbide skeleton on the inner side, which helps maintain the shape, and the skeleton of carbide gradually decreases toward the outer surface, and almost no points are formed on the outer surface. Support graphite powder by contact. Therefore, most of the surface of the hollow graphite molded product is made of graphite powder, and the lubricity and conductivity of graphite are kept good. Further, since the hollow graphite molded product is not a powder, the handling property becomes very good.

[0013]

【Example】

<Example 1> Flow beads CL-12007 (spherical polyethylene made by Sumitomo Seika Chemicals Ltd .; particle size range 900 to 11)
00 μm) as graphite powder CP (natural graphite graphite powder manufactured by Nippon Graphite Industry Co., Ltd .; average particle size 7.0 μm, particle size range 1 to 4)
5 μm) and then in air from room temperature to 300 ° C
Up to 600 ° C. in a nitrogen atmosphere after performing an infusibilizing treatment in which the temperature is raised up to about 1 ° C./minute and the temperature is kept at 300 ° C. for 1 hour
A baking treatment was performed at 1 ° C. for 1 hour. After the heat treatment was completed, excess graphite powder was removed by sieving to obtain a hollow graphite molded product.

Example 2 The flow beads CL-12007 used in Example 1 were replaced with flow beads CL-5.
A hollow graphite molded product was obtained in the same manner as in Example 1, except that the value was changed to 007 (a true spherical polyethylene manufactured by Sumitomo Seika Chemicals; particle size range: 300 to 400 μm).

<Embodiment 3> The flow beads CL-12007 used in Embodiment 1 were replaced with UBE: B-128.
(A polyethylene pellet for molding manufactured by Ube Industries, Ltd .; a cylindrical body having a diameter of about 5 mm and a height of about 3 mm)
A hollow graphite molded product was obtained in the same manner as in Example 1.

<Embodiment 4> The flow beads CL-12007 used in Embodiment 1 were replaced with TORAY: AQ-N.
A hollow graphite molded product was obtained in the same manner as in Example 1 except that YLON, P-20 (water-soluble nylon pellets manufactured by Toray Industries, Inc .; rectangular parallelepiped having a length of about 4 mm and a height of about 3 mm) was used. It was

<Fifth Embodiment> The flow beads CL-12007 used in the first embodiment are replaced with Dencast styrene: Q.
P-330 (manufactured by Denki Kagaku Kogyo KK, styrene pellets for molding; height about 2 mm, major axis about 3 mm, minor axis about 2 mm
A hollow graphite molded product was obtained in the same manner as in Example 1 except that the hollow graphite molded product was replaced by

<Example 6> In Example 1, the used flow beads CL-12007 was replaced with molding polyvinyl chloride resin pellets (a cylindrical body having a diameter of about 3 mm and a height of about 4 mm). Heat treatment in a nitrogen atmosphere from room temperature to 6
Raise the temperature up to 00 ° C at a rate of 1 ° C / min, and increase it to 600 ° C
A hollow graphite molded product was obtained in the same manner as in Example 1, except that the firing treatment was held for a time.

Example 7 The graphite powder CP used in Example 1 was replaced with graphite powder CSSP (Nippon Graphite Industry Co., Ltd.).
A hollow graphite molded product was obtained in the same manner as in Example 1, except that the natural scaly graphite powder manufactured by the present invention; average particle size 1.0 μm, particle size range 0.1 to 5 μm) was used.

<Comparative Example> In Example 1, except that the used Frobe's CL-12007 was replaced with molding phenol resin pellets (a cylindrical body having a diameter of about 3 mm and a height of about 4 mm). Same as Example 1. Only the carbide of the phenol resin was obtained, and no hollow graphite molded product was obtained.

[0021]

EFFECT OF THE INVENTION The hollow graphite molded product obtained according to the present invention has good handleability and excellent lubricity and conductivity. According to the present invention, such a hollow graphite molded product having excellent lubricity and conductivity can be easily obtained without requiring a complicated manufacturing process.

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[Procedure amendment]

[Submission date] February 1, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

As the graphite powder, any of natural graphite such as flake graphite, flake graphite, and soil graphite, and artificial graphite can be used. The intended use of the hollow graphite molded product to be obtained and the particle size of the particulate matter Considering the properties, thickness and length of graphite powder,
The particle size including the surface shape such as the grain size may be appropriately selected. The above-mentioned particulate matter is arranged in this graphite powder. In this case, it is sufficient if the graphite powder exists in a thickness equal to or greater than the wall thickness of the hollow graphite molded product to be obtained around the particulate matter. ..

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

[0021]

EFFECTS OF THE INVENTION Hollow graphite moldings obtained in the above examples
Means that, for example, those obtained in Examples 1 and 2 are spherical.
As shown in the figure,
The hollow graphite molded product obtained by the present invention has good handleability,
In addition, it has excellent lubricity and conductivity. According to the present invention, such a hollow graphite molded product having excellent lubricity and conductivity can be easily obtained without requiring a complicated manufacturing process.

Claims (1)

[Claims] 1. A thermoplastic resin particulate matter and graphite powder are used, and after the particulate matter is placed in the graphite powder, the surface of the particulate matter is once melted and then carbonized. , A method for producing a hollow graphite molded product having a large amount of carbide inside and a large amount of graphite powder outside.