JPS61295216A - Preparation of isotropic graphite material having high density and high strength - Google Patents

Abstract

PURPOSE:To prepare an isotropic graphite material having high density and high strength by kneading a mixture of calcined coke powder, graphite powder, and carbon black powder with a binder such as tar, etc., to form molded powder which is then calcined after hydrostatic compression molding and graphitizing. CONSTITUTION:45-97pts.wt. calcined coke powder prepd, by crushing coal or petroleum pitch coke to <=15mum mean particle size 1-15pts.wt. natural or artificial graphite powder having also <=15mum mean particle size, 2-40pts.wt. carbon black powder having <=0.4 times mean particle size of the mean particle size of calcined coke and 90-150pts.wt. tar or pitch as binder, are kneaded and crushed to prepare molded powder having <25mum mean particle size, which is molded by hydrostatic compression molding, calcined at 1,000 deg.C, graphitized then at 2,700 deg.C. Thus, isotropic graphite material having high density and high strength is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a high density, high strength isotropic graphite material.

(Prior Art) Generally, high-density and high-strength isotropic graphite materials are manufactured by the following method.

(1) Add sintering aid to raw coke and hot press.

(2) The fired body is impregnated with pitch, re-fired and graphitized.

(3) Pulverize the calcined coke and add a sintering aid.

(4) Use finely ground coke.

(Problems to be solved by the invention) (1) uses an expensive hot press, and (2) involves impregnation with pitch, resulting in high costs. Method (3) does not yield high-purity graphite, and method (4) produces tar.

The problem is that the amount of binder such as pitch added is large, making it difficult to adjust the volatile content.

(Means for Solving the Problems) An object of the present invention is to solve the above problems and provide a method for producing a high-density, high-strength isotropic graphite material.

The inventors of the present invention have conducted extensive research on two types of carbon aggregates, their particle sizes, and their blending ratios, and have discovered that by combining these, a high-density, high-strength isotropic graphite material can be obtained.

The present invention provides 45 to 97 parts by weight and 1 to 15 parts by weight of calcined coke powder and graphite powder with an average particle size of 15 μm or less, and a particle size of 0.4 times or less of the average particle size of the calcined coke powder. Add 90 to 150 parts by weight of a binder to carbon aggregate consisting of 2 to 40 parts by weight of carbon black, knead and crush to obtain a molded powder with an average particle size of 25 μm or less, and then hydrostatically press the molded powder. , relates to a method for producing high-density, high-strength isotropic graphite material by firing and graphitizing.

In the present invention, the calcined coke powder is one obtained by pulverizing, for example, coal-based or petroleum-based pitch coke, and its particle size is set to an average particle size of 15 μm or less. If it exceeds 15 μm, a graphite material with high density and high strength cannot be obtained. The graphite powder is artificial graphite powder or natural graphite powder, and its average particle size is 15 μm or less.

If it exceeds 15 μm, a graphite material with high density and high strength cannot be obtained. Carbon black is added to disperse between particles of calcined coke powder and graphite powder to reduce voids and create dense packing, and its particle size is 0.4 times or less the average particle size of calcined coke powder. be done.

If it exceeds 0.4 times, it becomes difficult to densely fill the carbon aggregate, and a graphite material with high density and high strength cannot be obtained. The preferred particle size is 1
0 to 500 nm. The types of carbon black are thermal black and lamp black.

Any material such as furnace black may be used.

The composition of each component in the carbon aggregate is calcined coke powder 45-97
Parts by weight, 1 to 15 parts by weight of graphite powder and 2 parts by weight of carphone black
~40 parts by weight. If it deviates from this range, a graphite material with high density and high strength cannot be obtained. Graphite powder is added to prevent cracks that tend to occur when calcined coke powder and carbon black shrink during heat treatment. Less than 1 part by weight has no effect, and more than 15 parts by weight reduces mechanical strength. I'll come.

The binder is preferably pitch or tar, and is used in an amount of 90 to 150 g parts per 100 parts by weight of the carbon aggregate.

If it is less than 90 parts by weight, a product with high density and uniform properties cannot be obtained, and if it exceeds 150 parts by weight, cracks, blisters, etc. will occur during the firing process.

Kneading (mixing) of the carbon aggregate and the binder is performed by a known method using, for example, a double-arm kneader. The mixed material is pulverized by a known method to obtain molded powder, and the molded powder has an average particle size of 25 μm.
The following shall apply. If it exceeds 25 μm, a graphite material with high density and high strength cannot be obtained.

If necessary, it is impregnated with pitch and subjected to a graphitization process to become a high-density, high-strength isotropic graphite material.

(Example) Next, the present invention will be explained in detail.

Example 1 75 parts by weight of coal-based pitch coke with an average particle size of 12 μm,
Carbon aggregate [, tar pitch (JI
SK 2439. General purpose medium pitch) and Engler viscosity 8 coal tar (JIS K 243
9. Add refined tar No. 1).

The mixture was heated to 200° C. and kneaded for 4 hours using a double-arm kneader. After pulverizing this mixed material with a pulverizer to an average particle size of 20 μm,
It was molded using a hydrostatic press, then fired at 1000°C, and graphitized at 2700°C.

Comparative Example 1 To 95 parts by weight and 5 parts by weight of the same pitch coke powder and artificial graphite powder as in Example 1, respectively, were added 70 parts by weight and 30 parts of the same tar pitch and coal tar as in Example 1, respectively. When part i was added and mixed, crushed, molded, and fired under the same conditions as in Example 1, blistering occurred during firing.

Comparative Example 2 65 parts by weight and 25 parts by weight of the same tar pitch and coal tar as in Example 1 were added to carbon aggregate having the same composition as in Comparative Example 1, and the mixture was mixed, crushed, and molded under the same conditions as in Example 1. , calcination and graphitization were performed.

Example 2 A carbon aggregate consisting of 80 parts by weight of petroleum-based pitch coke powder with an average particle size of 4 μm, 10 parts by weight of coke-based artificial graphite powder with an average particle size of 5 μm, and 10 parts by weight of furnace black with an average particle size of 40 nm, 100 parts by weight and 40 parts by weight of the same tar pitch and coal tar as in Example 1 were added, and the mixture was heated to 230° C. and kneaded for 4 hours in a double-arm kneader.

This mixed wire material was pulverized to an average particle diameter of 17 nm using a pulverizer, and then molded, fired, and graphitized in the same manner as in Example 1.

Table 1 shows the results of measuring the physical properties of test pieces made from the graphite materials obtained in Examples and Comparative Examples.

Table 1 As is clear from Table 1, the graphite material of Example 2 has larger values of apparent density, 9 bending strength, and hardness than the graphite material of Comparative Example 2.

(Effects of the Invention) According to the present invention, an isotropic graphite material with high density and high strength can be obtained.

Procedural amendment (voluntary) August 30, 1985

Claims (1)

[Claims] 1. 45 to 97 parts by weight of calcined coke powder and graphite powder with an average particle size of 15 μm or less, and 1 to 15 parts by weight, carbon black having a particle size of 0.4 times or less the average particle size of the calcined coke powder Add 90 to 150 parts by weight of a binder to carbon aggregate consisting of 2 to 40 parts by weight, knead and crush to obtain an average particle size of 2.
A method for producing a high-density, high-strength isotropic graphite material, which comprises obtaining molded powder of 5 μm or less, subjecting the molded powder to isostatic pressure molding, firing, and graphitizing it.