JP2002154874A - Method for manufacturing isotropic graphite material having high coefficient of thermal expansion and graphite tool and graphite base material each consisting of the isotropic graphite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a dense isotropic graphite material having high strength and a high coefficient of thermal expansion and to provide a graphite tool and to obtain a graphite base material consisting of the isotropic graphite material. SOLUTION: In the method for manufacturing an isotropic graphite material including a kneading process, isotropic forming process and carbonizing and graphitizing process, the kneading process is carried out by compounding crude cokes having 5 to 15 wt.% volatile matter and 4 to 20 μm average particle size with hard pitch having 70 to 90 mass% fixed carbon, 10 to 30 wt.% volatile content, 20 to 30 μm average particle size and >=200 deg.C softening point by 100:(40 to 250) compounding ratio by weight, and further by adding 5 to 60 pts.wt. tar to 100 pts.wt. of the crude cokes to knead the compound. Prior to pulverizing the obtained kneaded material, the kneaded material is heat treated in an inert atmosphere at 300 deg.C to 400 deg.C to remove the volatile matter in the tar by >=30 wt.%.

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 an isotropic graphite material having a high coefficient of thermal expansion, and a method for manufacturing a graphite made of the isotropic graphite material, which can be suitably used in semiconductor production and other fields. The present invention relates to a tool and a graphite base material suitable for forming an oxidation-resistant film and a corrosion-resistant film by a ceramic coating such as SiC.

[0002]

2. Description of the Related Art Generally, an industrial method for producing isotropic graphite material is a kneading method in which a pitch binder (binder) is mixed with an aggregate component composed of petroleum or coal coke powder and kneading treatment is performed. The process comprises a molding step of isotropically molding the raw material powder obtained by re-milling the kneaded product by a rubber press (cold isostatic press (CIP)), and a carbonization and graphitization step of firing and carbonizing the molded body. There are two types of coke, raw coke and calcined coke, depending on the heat history. The raw coke is used to remove heavy substances (bottom oil or coal tar) obtained from crude oil refining or coal dry distillation from 300 to 550.
It can be obtained by performing a thermal decomposition polymerization reaction by heating at a temperature of about ℃, and manufactured by various coking methods, and calcined coke is obtained by converting raw coke to a temperature of 1000 to 1500 ° C. using a rotary kiln or the like. Manufactured by heating and calcining.

[0003] Isotropic graphite materials are used in many fields such as sliding members, electrodes for electric discharge machining, for nuclear reactors, for semiconductors, and among them, wafers for heat treatment used in the semiconductor field. Jigs such as boats, liner tubes, process tubes, and susceptors for silicon epitaxial growth are coated with SiC for the purpose of improving oxidation resistance and preventing the release of adsorbed gas. If the coefficients of thermal expansion are significantly different, the coating (film) will break during the heating cycle and will no longer serve as a protective film. Therefore, it is preferable to match the two coefficients of thermal expansion.

Further, in a jig made of an isotropic graphite material used for positioning of a semiconductor ceramic package, brazing of a lead pin, a lead frame, etc., a dimension caused by a difference in thermal expansion between the ceramic substrate and the graphite jig. In order to avoid defects, particularly defects in pitch intervals between lead pins and lead frames, it is preferable that the coefficient of thermal expansion of the graphite material is approximately the same as the coefficient of thermal expansion of the ceramic. Therefore, isotropic graphite materials having a high coefficient of thermal expansion are desired. (See JP-A-63-310143)

[0005] According to the above-mentioned industrial production method of isotropic graphite material,
For example, 2.8 to 7.9 × 10 ^-6/ Expansion in the range of / K
An isotropic graphite material with a tensile modulus can be obtained (revised carbon
Introduction to Materials, Issued in 1984 by the Society of Carbon Materials, No. 171
page). Manufacturing of isotropic graphite with high thermal expansion coefficient
As a law, for example, in Japanese Patent Publication No. Sho 60-5523,
Microcrystalline pitch coke, mosai like phenanthrene
Isotropic or microcrystalline structure with a structural unit of less than 10 microns
Mixed with commercially available low expansion coke
Heat-expandability of various coating materials
A method for obtaining an isotropic graphite material consistent with
As an example, coal tarp
And kneading, kneading and shaping.
The thermal expansion coefficient is 6.9 × 10^-6/
To obtain an isotropic graphite material at 350 ° C (350-450 ° C)
Have been.

[0006] From raw coke, the average particle size is 1-20.
μm, an axial ratio of 1.0 to 1.3, a specific toluene-insoluble content,
A coke having a quinoline-insoluble content and a volatile content is obtained by a solvent separation method, and this special coke is isotropically molded.
By firing at 00 ° C and graphitizing at 2800 ° C,
It is also disclosed to produce an isotropic graphite material having a coefficient of thermal expansion of 5.89 to 6.28 × 10 ⁻⁶ / ° C. (Japanese Patent Publication No. 3-69845). However, there is a problem that the preparation of the raw material is troublesome and the cost is increased.

[0007] As a method for producing an isotropic graphite material using raw coke such as commercially available raw coke as a raw material, a fine pulverized raw coke or a binder pitch which is sintered without melting during firing. A method is also disclosed in which a mixture of the above is molded under pressure, the molded body is primarily baked at a temperature of 450 to 700 ° C., then pitch-impregnated under pressure, and further subjected to a high-temperature calcination treatment (Japanese Patent Publication No. 57-25484). According to this method, a high-density isotropic graphite material having a bulk density exceeding 1.8 and having excellent strength characteristics can be obtained, but this method is intended for obtaining high strength. However, a sufficiently high value of the coefficient of thermal expansion is not necessarily obtained, and a treatment of impregnation and re-firing is required after firing, so that there are problems such as a complicated process and a large consumption of heat energy. That.

[0008] The present inventors have solved the above-mentioned conventional problems in the production of isotropic graphite material, and have a high coefficient of thermal expansion that is economically advantageous using ordinary raw coke without using coke having special properties. In order to obtain an isotropic graphite material having, raw calcined coke or calcined coke produced by heating and calcining raw coke as a raw material, in particular, the properties of hard pitch to be mixed with this, tar As a result of reviewing and reviewing the relationship between the adjustment of the kneaded material and the coefficient of thermal expansion of the obtained graphite material, the use of mosaic or needle-like raw coke, and the specified properties, especially A hard pitch having a softening point is blended, kneaded using a specific amount of tar as a medium, and the kneaded product is heat-treated at a specific temperature and atmosphere before molding, firing, and graphitizing the kneaded product. The volatiles were removed certain amount or more in,
It has been found that when the kneaded material is adjusted, an isotropic graphite material having a high coefficient of thermal expansion can be obtained.

[0009]

SUMMARY OF THE INVENTION The present invention has been made based on the above findings, and has as its object to provide an isotropic graphite material having a high coefficient of thermal expansion, high density and high strength. Is to be economically and advantageously produced by using ordinary raw coke as a raw material. Another object of the present invention is to provide a graphite jig made of the isotropic graphite material and suitable for semiconductors and the like, and a coating base material such as SiC.

[0010]

According to a first aspect of the present invention, there is provided a method for producing an isotropic graphite material, which comprises mixing and kneading a pitch binder with an aggregate component of a carbonaceous powder. In a method for producing an isotropic graphite material comprising a kneading step, a step of isotropically molding a powder obtained by pulverizing a kneaded product, and a carbonization and graphitization step of calcining and graphitizing the molded body, the kneading step is performed by volatilization. 5 to 15% by weight, raw coke having an average particle size of 4 to 20 μm, fixed carbon amount of 70 to 90% by weight, volatile matter of 10 to 30% by weight, average particle size of 20 to 30
μm, a soft pitch having a softening point of 200 ° C. or more
0: 40-250 weight ratio, kneading by adding 5-60 parts by weight of tar to 100 parts by weight of the raw coke, and kneading the obtained kneaded material prior to pulverization. The object is placed in an inert atmosphere at 300 to 400 ° C.
Heat treatment at a temperature of 30% by weight of the volatile matter in the tar
It is characterized by removing the above.

According to a second aspect of the present invention, in the method for producing an isotropic graphite material according to the first aspect, after removing volatile components in the tar of the kneaded material, the kneaded material is exposed to a temperature of 130 to 200 ° C. in air. It is characterized by the following.

According to a third aspect of the present invention, there is provided the method for producing an isotropic graphite material according to the first or second aspect, wherein
It is characterized by being crushed to 0 μm to obtain a powder.

A graphite jig according to a fourth aspect of the present invention is an isotropic graphite material produced by kneading raw raw coke and hard pitch as aggregate components, and pulverizing, shaping, calcining and carbonizing the kneaded material. And a bulk specific gravity of 1.8 or more, a thermal expansion coefficient of 7.0 × 10 ⁻⁶ / K or more, a hardness (H _S ) of 70 or less, an anisotropic ratio of electric resistivity of 1.03 or less, and obtained by X-ray diffraction. The half width of the d002 plane has a property of 0.3 to 0.5 degrees.

The graphite base material according to claim 5 is an isotropic graphite material produced by kneading raw raw coke and hard pitch as aggregate components, and pulverizing, shaping, calcining and carbonizing the kneaded product. And a bulk specific gravity of 1.8 or more, a thermal expansion coefficient of 7.0 × 10 ⁻⁶ / K or more, a hardness (H _S ) of 70 or less, an anisotropic ratio of electric resistivity of 1.03 or less, and obtained by X-ray diffraction. The half width of the d002 plane has a property of 0.3 to 0.5 degrees.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing an isotropic graphite material of the present invention will be described. (Aggregate Component) In the present invention, petroleum or coal-based raw coke is used as a raw material constituting the aggregate component of the carbonaceous powder. Both mosaic coke and needle coke can be used. As described above, raw coke is obtained by heating a heavy substance (bottom oil or coal tar) obtained from crude oil refining or coal dry distillation at a temperature of about 300 to 550 ° C. to perform a thermal decomposition polymerization reaction. It is manufactured by various caulking methods. Raw coke is heated to a temperature of about 120 to 150 ° C in advance and dried to remove moisture contained in it, and then pulverized and ground in order to express the isotropic property of the graphite material and to impart tissue homogeneity. By doing so, the average particle diameter is adjusted to 4 to 20 μm. Very little adjustment of volatiles is required. The measurement of volatile components is performed according to JIS M8812.

(Binder) Hard pitch as a binder to be added to the aggregate component is produced by further heating the hard pitch among the hard, medium and soft pitches obtained by carbonization of coal. In the present invention, a hard pitch having a fixed carbon content of 70 to 90% by weight, a volatile content of 10 to 30% by weight, an average particle diameter of 20 to 30 μm, and a softening point of 200 ° C. or more is blended. In particular, it is preferable to use a hard pitch having a high softening point in order to reduce the volatile matter contained in the molded body and obtain an isotropic graphite material having a fine and uniform texture, more preferably 300 ° C. or higher, Preferably 32
A hard pitch having a softening point of 0 ° C. or higher is used. In addition,
Measurements of fixed carbon content, volatile matter and softening point
ISK2425, JIS M8812 and JIS K
2425.

(Mixing of raw coke and hard pitch) The mixing ratio of hard pitch to raw coke is 40 to 250 hard pitches per 100 raw coke in weight ratio.
When the compounding ratio of the hard pitch is less than 40, the specific gravity and strength of the obtained isotropic graphite material is reduced, and when the compounding ratio of the hard pitch exceeds 250, the obtained isotropic graphite material is foamed and the uniformity of the structure is increased. Properties are reduced, and sufficient strength cannot be obtained. The preferred mixing ratio of the hard pitch to the raw coke 100 is 150 to 180 parts by weight.

(Kneading) In order to uniformly disperse the compounded powder, the mixture is preferably stirred and mixed by using a tar having a fixed carbon content of 15% by weight or less as a medium by a device such as a kneader or a mixer. The amount of tar added is preferably 5 to 60 parts by weight based on 100 parts by weight of raw coke. If the amount is less than 5 parts by weight, the tar does not uniformly spread over the powder, and the uniformity of the kneaded product is reduced. If the amount exceeds 60 parts by weight, an excessive tar component is separated from the separated material, and the uniformity of the kneaded product is reduced.
A more preferable addition amount of the pitch is 30 to 40 parts by weight based on 100 parts by weight of the raw coke.

(Preparation of kneaded product) (1) Prior to pulverizing the obtained kneaded product, the kneaded product is placed in an inert atmosphere such as a nitrogen gas atmosphere for 300 to 4 minutes.
Heat-treated at a temperature of 00 ° C., and
Remove more than weight%. In order to uniformly remove volatile components and adjust the properties of the hard pitch and tar, it is desirable to form the kneaded product into uniform dimensions by means of a briquette machine, molding, or CIP molding.
The heat treatment time depends on the shape of the kneaded product, but is 0.5 to 10 hours.
Preferably, it is time.

(2) After the heat treatment, the kneaded product is exposed to a temperature of 130 to 200 ° C. in the air, if necessary, to adjust the volatile content to 15 to 25% by weight.

(Pulverization) The heat-treated kneaded product is pulverized to an average particle diameter of 10 to 60 μm.

(Molding, sintering, graphitization) The powder produced by pulverizing the kneaded product isotropically molded by CIP (cold isostatic pressure) molding according to a conventional method. Carbonized at a temperature of 25 ° C., for example, 25
Graphitization is performed at a temperature of 00 to 3000 ° C. to obtain an isotropic graphite material.

Among the isotropic graphite materials produced as described above, kneaded raw coke and hard pitch are used as aggregate components, and isotropically formed by grinding, molding, calcining and graphitizing the kneaded material. Graphite material has a bulk specific gravity of 1.8 or more,
Thermal expansion coefficient 7.0 × 10 ^-6 / K or more, hardness (H _S ) 70
Hereinafter, the anisotropic ratio of the electrical resistivity is 1.03 or less, the half-width of the d002 plane obtained by X-ray diffraction is 0.3 to 0.5 degrees, the high thermal expansion coefficient, and the low hardness that is easy to process. It is particularly suitable for use as a jig for semiconductor production and a substrate for ceramic coating such as SiC coating. If the half-width of the d002 plane obtained by X-ray diffraction is less than 0.3 degrees, a high coefficient of thermal expansion cannot be obtained, and 0.
If it exceeds 5 degrees, low hardness cannot be obtained and processing becomes difficult.

[0024]

Hereinafter, examples of the present invention will be described in comparison with comparative examples. This example shows one embodiment of the present invention, and the present invention is not limited to this.

Example 1 Massive mosaic raw coke (manufactured by Mitsubishi Chemical Corporation) was
After heating and holding at a temperature of 120 ° C. using a drying oven to remove water, the mixture was pulverized by a pulverizer to an average particle diameter of 13 μm. 10 kg of the pulverized raw coke (volatile content: 13.5% by weight) and a hard pitch (TGP- manufactured by Osaka Chemical Industry Co., Ltd.)
2000, fixed carbon amount 85.0% by weight, volatile matter 14.5
Weight%, softening point 320 ° C, average particle size 20μm) 15k
g, and the resulting mixture was charged into a mixer together with 3.7 kg of tar and kneaded for 1 hour.

The obtained kneaded material is molded into a mold for about 3 hours.
Each of the rectangular parallelepipeds was charged into a heating furnace, and cooled to a temperature of 350 ° C. while flowing nitrogen gas.
A heat treatment for holding for a time was performed. After heat treatment, cool to room temperature, pulverize the rectangular parallelepiped to an average
Furthermore, it was heated and maintained at 200 ° C. in an air atmosphere in a heating furnace, and the volatile content was adjusted to 18% by weight.

Then, the mixture is cooled to room temperature, pulverized to an average particle diameter of 25 μm with a pulverizer, and the pulverized raw material powder is charged into a rubber mold and deaerated. Charged to a molding machine, 98.1MPa (1000kg
/ Cm ³ ) at a pressure of 400 mm long, 400 mm wide and 100 mm thick.

The molded body is heated to a temperature of 900 ° C. in a firing furnace filled with coke powder and fired.
Heat treatment was performed at a temperature of 800 ° C. to obtain an isotropic graphite material.
From the obtained isotropic graphite material, a diameter of 10 mm and a length of 100 mm
mm of a test material, and (1) bulk specific gravity, (2) coefficient of thermal expansion, (3) bending strength, (4) electrical resistivity, (5) anisotropy of resistivity, 6) Half width at d002 plane obtained by X-ray diffraction, (7) Structure observation. Table 1 shows the results.

(1) Measurement of bulk specific gravity: Calculated by measuring the size with a caliper and measuring the weight with a balance. (2) Measurement of coefficient of thermal expansion (CTE): temperature range 30 to
Measure at 900 ° C. using quartz as a standard sample. (3) Measurement of bending strength: Measured according to JIS R7222. (4) Measurement of electric resistivity: Measured according to JIS R7222. (5) Measurement of resistivity anisotropy: The resistivity was measured according to JIS R72.
Measure according to No. 22 and determine the anisotropy from the measured values. (6) Measurement of half width of d002 surface: Japan Society for the Promotion of Science No. 1
The measurement is performed according to "Method for measuring lattice constant and crystallite size of artificial graphite" prepared by the 17th Committee. (7) Microstructure observation: Observation is performed with a microscope (× 200), and a fine and uniform microstructure is regarded as good.

Example 2 As raw coke, acicular raw coke (manufactured by Mitsubishi Chemical Corporation)
An isotropic graphite material was obtained in the same manner as in Example 1 except that 10 kg was used.

Example 3 A hard pitch (MCP manufactured by Adchemco Co., Ltd.) was used as the pitch.
-200, fixed carbon amount 73.0% by weight, volatile matter 26.5
Weight%, softening point 200 ° C, average particle size 20μm) 15k
An isotropic graphite material was obtained in the same manner as in Example 1 except that g was blended.

Example 4 A hard pitch (MCP manufactured by Adchemco Co., Ltd.) was used as the pitch.
-250, fixed carbon amount 78.0% by weight, volatile matter 21.5
Weight%, softening point 250 ° C, average particle size 20μm) 15k
An isotropic graphite material was obtained in the same manner as in Example 1 except that g was blended.

Example 5 As raw coke, acicular raw coke (manufactured by Mitsubishi Chemical Corporation)
Using 10 kg, 15 kg of hard pitch (MCP-250 manufactured by Adchemco Co., Ltd., fixed carbon amount: 78.0% by weight, volatile matter: 21.5% by weight, softening point: 250 ° C., average particle diameter: 20 μm) is blended as the pitch. An isotropic graphite material was obtained in the same manner as in Example 1 except for the above.

Example 6 As raw coke, acicular raw coke (manufactured by Mitsubishi Chemical Corporation)
Using 10 kg, 15 kg of hard pitch (MCP-300 manufactured by Adchemco Co., Ltd., fixed carbon amount 83.0 wt%, volatile matter 16.5 wt%, softening point 300 ° C., average particle diameter 20 μm) is blended as the pitch. An isotropic graphite material was obtained in the same manner as in Example 1 except for the above.

Comparative Example 1 Mosaic raw coke of Example 1 (manufactured by Mitsubishi Chemical Corporation)
Was heat-treated at a temperature of 1200 ° C. and then pulverized with a pulverizer to an average particle diameter of 13 μm to obtain calcined coke. Using 10 kg of this calcined coke as an aggregate component, a hard pitch was blended in the same manner as in Example 1, and an isotropic graphite material was obtained in the same manner as in Example 1.

Comparative Example 2 Needle-like raw coke (manufactured by Mitsubishi Chemical Corporation) of Example 2
After heat treatment at a temperature of 00 ° C., a pulverizer was used to obtain an average
It was pulverized to μm to obtain calcined coke. Using 10 kg of this calcined coke as an aggregate component, a hard pitch was blended in the same manner as in Example 1, and an isotropic graphite material was obtained in the same manner as in Example 1.

Comparative Example 3 15 kg of hard pitch (TGP-2000 manufactured by Osaka Kasei Co., Ltd., fixed carbon amount 85.0% by weight, volatile matter 14.5% by weight, softening point 320 ° C., average particle diameter 20 μm) and tar 3 .
7 kg was charged into a mixer and kneaded for 1 hour.

The obtained kneaded material is molded into a mold for about 3 hours.
Each of the rectangular parallelepipeds was charged into a heating furnace, and cooled to a temperature of 350 ° C. while flowing nitrogen gas.
A heat treatment for holding for a time was performed. After heat treatment, cool to room temperature, pulverize the rectangular parallelepiped to an average
Furthermore, it was heated and maintained at 200 ° C. in an air atmosphere in a heating furnace, and the volatile content was adjusted to 18% by weight.

Then, the mixture is cooled to room temperature, pulverized to an average particle diameter of 25 μm with a pulverizer, and the pulverized raw material powder is charged into a rubber mold and deaerated. Charged to a molding machine, 98.1MPa (1000kg
/ Cm ³ ) at a pressure of 400 mm long, 400 mm wide and 100 mm thick.

The compact was heated to 900 ° C. in a firing furnace filled with coke powder and fired.
When heat treatment was performed at a temperature of 800 ° C., the obtained graphite material was cracked, and the test material could not be collected.

Comparative Example 4 Raw coke (manufactured by Mitsubishi Chemical Corporation) was used as coke.
Using 10 kg, 15 kg of hard pitch (GPC-730 manufactured by Osaka Chemical Industry Co., Ltd., fixed carbon amount 75.0% by weight, volatile matter 24.5% by weight, softening point 150 ° C., average particle diameter 20 μm) as a pitch. Except for blending, an isotropic graphite material was obtained in the same manner as in Example 1.

Comparative Example 5 As raw coke, acicular raw coke (manufactured by Mitsubishi Chemical Corporation)
Hard pitch (ADP manufactured by Adchemco Co., Ltd., fixed carbon amount: 58.0% by weight, volatile matter: 41.5% by weight, softening point: 100 ° C., average particle diameter: 20 μm)
m) An isotropic graphite material was obtained in the same manner as in Example 1 except that 15 kg was blended.

Comparative Example 6 As a coke, 10 kg of mosaic raw coke (manufactured by Mitsubishi Chemical Corporation) was used, and as a pitch, a hard pitch (GPC-730 manufactured by Osaka Chemical Co., Ltd., fixed carbon amount: 7)
5.0% by weight, volatile matter 24.5% by weight, softening point 150
° C, average particle size 20 μm)
An isotropic graphite material was obtained in the same manner as in Example 1.

Test materials similar to those in Example 1 were collected from the isotropic graphite materials obtained in Examples 2 to 6 and Comparative Examples 1 to 2 and 4 to 6, and a bulk material was obtained in the same manner as in Example 1. Specific gravity, thermal expansion coefficient, bending strength, electrical resistivity, anisotropy of resistivity, half width of d002 plane obtained by X-ray diffraction, and structure observation were performed. Table 1 shows the measurement and observation results of Examples 2 to 6, and Table 2 shows the measurement and observation results of Comparative Examples.

[0045]

[Table 1]

[0046]

[Table 2]

As can be seen from Table 1, all of the test materials of Examples 1 to 6 according to the present invention show dense and homogeneous properties and have a high thermal expansion coefficient of 7.0 or more. The test materials of Examples 2 and 5 and 6 using needle-like raw coke as a raw material have a high coefficient of thermal expansion, are low in hardness and excellent in workability, and are particularly suitable for jigs and ceramics for semiconductor production. It is suitable as a substrate for coating.

On the other hand, as shown in Table 2, the test materials of Comparative Examples 1 and 2 using calcined coke as a raw material had a low coefficient of thermal expansion and Comparative Examples 4 to 4 using hard pitch having a low softening point. Each of the test materials of No. 5 had a rough structure, strength,
The hardness was also low, and the test material of Comparative Example 6 had cracks.

[0049]

As described above, according to the present invention, an isotropic graphite material which is dense, has high strength, has a high coefficient of thermal expansion, and is economically advantageous is produced. Isotropic graphite material produced according to the present invention using acicular raw coke as a raw material,
It has a high coefficient of thermal expansion and low hardness, so it is excellent in workability and can easily perform fine processing. Especially, jigs for semiconductor production such as wafer boats, liner tubes, process tubes, and susceptors Or as a substrate for ceramic coating.

Continued on the front page (72) Inventor Takashi Nagase 1-3-2 Kitaaoyama, Minato-ku, Tokyo Tokai Carbon Co., Ltd. F-term (reference) 4G032 AA03 AA09 BA01

Claims (5)

[Claims] 1. A kneading step of mixing and kneading a pitch-based binder with an aggregate component of a carbonaceous powder, a step of isotropically forming a powder obtained by pulverizing a kneaded product, and calcining and graphitizing the formed body. In the method for producing an isotropic graphite material comprising a carbonization and graphitization step, the kneading step comprises: raw coke having a volatile content of 5 to 15% by weight and an average particle diameter of 4 to 20 μm;
90% by weight, volatile matter 10-30% by weight, average particle size 2
A step of compounding a hard pitch having a softening point of 200 ° C. or higher at a weight ratio of 100: 40 to 250, adding a tar of 5 to 60 parts by weight to 100 parts by weight of the raw coke, and kneading the mixture. Consisting of, prior to pulverizing the obtained kneaded product, the kneaded product is in an inert atmosphere, 300 ~
Heat-treated at a temperature of 400 ° C., and 3
A method for producing an isotropic graphite material having a high thermal expansion coefficient, wherein 0% by weight or more is removed. 2. The production of an isotropic graphite material according to claim 1, wherein after removing volatile components in the tar of the kneaded material, the kneaded material is exposed to a temperature of 130 to 200 ° C. in air. Method. 3. The method for producing an isotropic graphite material according to claim 1, wherein the kneaded material is pulverized to 10 to 60 μm to obtain a powder. 4. An isotropic graphite material produced by kneading acicular raw coke and hard pitch as aggregate components, and pulverizing, molding, calcining and graphitizing the kneaded product, and having a bulk specific gravity of 1.8. As described above, the thermal expansion coefficient is 7.0 × 10 ⁻⁶ / K or more,
Hardness (H _S ) 70 or less, anisotropic ratio of electric resistivity 1.03 or less, and half-width of d002 plane obtained by X-ray diffraction of 0.
A graphite jig having a property of 3 to 0.5 degrees. 5. An isotropic graphite material produced by kneading acicular raw coke and hard pitch as aggregate components, and pulverizing, molding, calcining and graphitizing the kneaded product, and having a bulk specific gravity of 1.8. As described above, the thermal expansion coefficient is 7.0 × 10 ⁻⁶ / K or more,
Hardness (H _S ) 70 or less, anisotropic ratio of electric resistivity 1.03 or less, and half-width of d002 plane obtained by X-ray diffraction of 0.
A graphite substrate having a property of 3 to 0.5 degrees.