JPS5913614A - Manufacture of carbonaceous material of low elasticity - Google Patents

Abstract

PURPOSE:To obtain easily a carbonaceous material with low elasticity and high bending strength by substituting a material formed by expanding artificial graphite granules for part of a carbonaceous material, adding a binder, kneading them, and molding and calcining the kneaded material. CONSTITUTION:A material formed by expanding artificial graphite granules made from petroleum coke or coal coke is substituted for at least 20wt% of a carbonaceous material, and a binder is added. They are kneaded, and the kneaded material is molded and calcined. By this method a molded body of a carbonaceous material or a graphitic material with low elasticity, high bending strength and high electric conductivity is obtd. The molded body is suitable for use as an electric brush, a gasket, packing, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a molded body of carbon material or graphite material, and its object is to produce a carbon material or graphite material that has low elasticity, high bending strength, and electrical type conductivity. The object of the present invention is to provide a molded article.

Conventionally, carbon material or graphite material molded bodies are made of petroleum coke,
It is manufactured by adding a binder such as coal tar or coal tar pitch% synthetic resin to a carbon material such as coal coke, pitch coke, or carbon black, mixing it, forming it, firing it, and then graphitizing it if necessary. Therefore, in the firing process and graphitization process, as the processing temperature increases,
Further, as the treatment time becomes longer, the elastic modulus of the obtained molded body of carbon hamura or graphite material tends to decrease, and the bending strength and electrical conductivity also tend to decrease. Therefore, it is nearly impossible to manufacture a carbon or graphite material molded body with a low elastic modulus and high bending strength and electrical conductivity, and therefore, in fields where a low elastic modulus molded body is required, Despite being insufficient in terms of bending strength and electrical conductivity, such molded bodies are currently being used in this field.

In view of the current situation, the present inventor has conducted extensive research in order to develop a method for producing a molded body of carbon or graphite material that has low elasticity, high bending strength, and high electrical conductivity, and has finally completed the present invention. I was able to complete it.

That is, the present invention provides a method for producing a carbon material or a graphite material molded body by adding a binder to a carbon material, cross-wiring, forming and firing it, and graphitizing it if necessary.
The present invention relates to a method for producing a molded body of a carbon material or graphite material, characterized in that 0% by weight is replaced with a material obtained by subjecting artificial graphite particles made from petroleum coke or coal coke to an expansion treatment.

In the method of the present invention, even by increasing the treatment temperature or lengthening the treatment time in the firing step and the graphitization step, the bending strength and electrical conductivity hardly decrease, and only the elastic modulus remains. can be lowered. Therefore, according to the method of the present invention, it is possible to produce a molded body of carbon material or graphite material that has low elasticity and at the same time has practically sufficient bending strength and electrical conductivity. Furthermore, according to the method of the present invention, the desired elastic modulus can be achieved by appropriately selecting the amount of material used for expanding artificial graphite particles, the treatment temperature and treatment time in the firing process and the graphitization process. It is possible to produce a molded body of a carbon material or a graphite material. The molded article obtained by the method of the present invention is
Fields that require thermal shock resistance such as electrical discharge machining, trays for sintering furnaces, susceptors for semiconductors, and nozzles for casting equipment, and low elasticity such as electric brushes, vanes for rotary compressors, vanes for vacuum pumps, gaskets, and packings. It can be suitably used in the field of

As the carbon material used in the present invention, a wide variety of conventionally known carbon materials can be used, such as petroleum coke, coal coke, pitch coke, carbon black, etc. In the present invention, at least 20% by weight of the carbon material
It is essential to replace it with a material made by expanding artificial graphite particles made from petroleum coke or coal coke.

The material obtained by subjecting the artificial graphite particles to an expansion treatment can be obtained by, for example, immersing the artificial graphite particles in a strongly oxidizing solution, washing the graphite particles with water as necessary, and then heating the graphite particles. is manufactured. As the artificial graphite particles used here, a wide variety of conventional graphite particles can be used as long as they are made from petroleum coke or coal coke, such as gilt night coke, needle coke, regular coke, etc. Examples of strong oxidizing solutions include oleum, concentrated sulfuric acid, nitric acid, fuming nitric acid, concentrated nitric acid, a mixture of concentrated sulfuric acid and concentrated nitric acid, a mixture of concentrated sulfuric acid and nitric acid, concentrated sulfuric acid and hydrogen peroxide, and perchloric acid. , a mixture of an oxidizing agent such as manganese dioxide (the oxidizing agent usually contains 5 to 50 ml of oxidizing agent), and the like. The amount of the strongly oxidizing solution to be used is not particularly limited and can be appropriately selected from within a wide range, but it is sufficient that the artificial graphite particles to be treated can be sufficiently immersed in the strongly oxidizing solution. Usually about 3 to 30% by weight for artificial graphite particles
A strong oxidizing solution of 30% is used. The subsequent washing with water is carried out for the purpose of partially hydrolyzing the graphite interlayer compound and trapping the remaining compound within the graphite interlayer as a substance necessary for expansion.

However, in the present invention, the desired effects of the present invention can be exhibited even without washing with water. The heating temperature is not limited to Samurai, but is generally 200°C or higher, usually 200 to 14°C.
It may be within the range of 00°C. Although the heating time varies depending on the heating temperature and the like, it is usually about 2 to 60 seconds. Furthermore, in the present invention, instead of immersing the artificial graphite particles in a strongly oxidizing solution, the graphite particles may be immersed in dilute nitric acid for electrolytic treatment. Thus, the artificial graphite particles have a particle size of about 1.1~
A twice expanded material is produced. In the present invention, a carbon material in which at least 20 parts of the carbon material is replaced with a material obtained by subjecting the artificial graphite particles to an expansion treatment is used. When the expansion treatment is applied and the proportion of the material used is less than 20 times, the intended effect of the present invention tends to be less likely to be achieved. In the present invention, it is of course possible to use only the expanded material as the carbon material.

As the binder used in the present invention, a wide variety of conventionally known binders can be used, such as coal tar, coal tar pitch, synthetic resins, and the like.

In the present invention, the ratio of the carbon material and the binder to be used is not particularly limited and can be appropriately selected within a wide range, but it is usually preferable to use the latter in an amount of about 20 to 40% of the former. When the amount of binder used is less than lθ, the mechanical strength after carbonization tends to decrease, while when the amount of binder used is more than 60% by weight, the porosity after carbonization tends to decrease. A tendency to increase occurs.

In order to produce the low modulus carbon material of the present invention, kneading, molding, firing and graphitization can be carried out using conventional mixing machines such as kneaders and rollers. It can be done using Further, when performing molding, any conventionally known molding method such as die pressing, extrusion molding, rubber press molding, etc. can be employed.

For example, stamp molding or extrusion molding can yield a molded product with anisotropic crystal orientation, while rubber press molding can yield a molded product with isotropic crystal orientation. The pressure during molding is not particularly limited, but is usually a surface pressure of 500 to 15
00 preferably 700 to 10100 and 9/c-.

Firing is usually 700-1200, preferably 900-110
It is best to carry out the firing at a temperature of about 0°C, and the firing time is generally about 4
0 to 80 hours. Graphitization is usually 2000~30
00'C Preferably, it is carried out at about 2500 to 2900°C, and the time required for graphitization is generally about 20 to 4
It is 0 hours. In this way, a desired carbon material or graphite material molded body can be obtained.

Reference examples and examples are listed below.

Reference example: Artificial graphite with an average diameter of 80 μm was mixed with concentrated sulfuric acid (concentration 97% or higher) and diconcentrated nitric acid (concentration 6°C or higher) at a volume ratio of 9:1 (10 times the concentration for heavy fibers) at a temperature of 100°C. 10
It was immersed for a minute while stirring with a glass rod. Then put it in an electric oven for 60 seconds at a temperature of too much.

The volume was expanded by 1.3 times by heating to .degree. A material subjected to expansion treatment (hereinafter referred to as "expansion treatment material") was thus obtained.

Example The expanded material obtained in the above reference example and petroleum coke were appropriately mixed to prepare a carbon material. A binder was added to the kernel mixture in an amount of 30% based on the total amount, and the mixture was mixed while being heated to 150° C. in a kneader.

(1) Production of y% isotropic molded product The above mixture was placed in an embossing type mold, and the surface pressure was 1000.
kg/crA for 60 seconds from two opposing sides and fired at 7.1000°C to produce a carbon feed molded body.

The physical properties of the obtained molded product are shown in Table 1 below. In addition, graphite material molded bodies were also prepared by heat-treating the above-mentioned carbon material molded bodies in an electric furnace at a maximum straw temperature of 2700 T and a current running time of 120 hours. The physical properties of the obtained molded product are shown in Table 2 below.

/''' / / (2) Production of isotropic molded product The above mixture was placed in a rubber press machine and a surface pressure of 1000
It was press-molded at tog/cJ for 60 minutes and fired at 1000°C to create a carbon material molded body. The physical properties of the molded product obtained are shown in Table 3 below. Regarding graphite material molded bodies, the above carbon material molded bodies are heated in an electric furnace at a maximum temperature of 2700°C.
It was created by heat treatment for 120 hours of current application. The physical properties of the molded product obtained are shown in Table 4 below.

The time required for copperization is generally about 20 to 40 hours. In this way, a desired carbon material or graphite material molded body can be obtained.

As is clear from the above examples and comparative examples, the average bending strength/elastic modulus of the conventional method is 0.29 (carbon material) and 0.3.
7 (graphite material), but in the present invention, only the expansion treated material is used as the carbon material. In the case of 9, the average bending strength/modulus of elasticity is 0.37 (carbon material) and 0.46 (graphite material).
In addition, the amount of change in the elastic modulus with respect to the average bending strength is large, and it is an extremely effective method for changing the elastic modulus depending on the application. In addition, the expansion treated material lo with the smallest elastic modulus
Even in the case of 0, the average bending strength and the electrical specific resistance both show high values and do not cause any practical problems.

On the other hand, thermal shock resistance is calculated using the formula % E: Young's modulus (Y/CRA) 8: Mechanical strength (Y/CF) K: Thermal conductivity (Cal/Cm, sec, °C) α
: Coefficient of thermal expansion (to, /') The mechanical strength and thermal conductivity are preferably high, and the Young's modulus and thermal expansion coefficient are preferably low.

As estimated from the above example, in the case of the expanded material "toos" having the lowest elastic modulus, the absolute value of the bending strength corresponding to the mechanical strength is high and shows a tendency almost similar to the thermal conductivity.

The absolute value of the electrical resistivity is high, and the Young's modulus and thermal expansion coefficient are low, so the thermal shock resistance tends to be good.

(that's all)

Claims (1)

[Claims] ■ Add a binder to the carbon material, cross-wire, shape and sinter,
Furthermore, when graphitizing as necessary to produce a carbon material or a graphite material molded body, at least 20% by weight of the carbon material.
A method for producing a molded body of a carbon material or a graphite material, characterized in that the material is replaced with a material obtained by subjecting artificial graphite particles made from petroleum coke or coal coke to an expansion treatment.