JPH01290559A - Production of high-density carbon material - Google Patents

Abstract

PURPOSE:To efficiently obtain the title material having an excellent sealing property by pulverizing mesocarbon globules to less than a specified diameter when the globules having a self-sintering property are pulverized, formed without using a binder, and calcined. CONSTITUTION:Tar, pitch, etc., are heat-treated, and the self-sintering mesocarbon globules having >=10mum average diameter are separated from the pitch matrix in the heat-treated pitch. The globules are then pulverized to obtain the powder having <=5mum average particle diameter. The powder is formed without using a binder, and calcined. In this case, smaller pulverized globules are preferably used from the standpoint of the sealing property. However, excessive pulverization is not favorable from the economical point of view. Consequently, the globules are generally crushed to <=5mum, and the sealing property for gas or liq. required as the carbon for machine can be secured though it depends on a thickness of a product.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a high-density carbon material from self-sintering mesocarbon spherules without using a binder.

<Prior art> As a method for manufacturing high-density, high-strength carbon materials without using a binder, a heat-treated product obtained by heat-treating pitches is directly pulverized to 10 μm or less, or a molded product is pulverized during firing. In order to prevent melting, a method has been proposed in which a finely ground product obtained by additionally introducing oxidation treatment into the heat treatment process is used (Japanese Patent Publication No. 53-18359, Japanese Patent Publication No. 53-18359,
-42823). However, in these methods, it is difficult to carry out quality adjustment for imparting self-sintering power in a single heat treatment, and industrially stable production is difficult and reproducibility is difficult. In addition, since this heat-treated product is a coke-like substance, it is easily broken into needles and leaves during crushing, and anisotropy is likely to occur in the molded product.Furthermore, because the pre-heat treatment temperature is high, coke is generated during firing of the molded product. Another problem is that shrinkage occurs rapidly at high temperatures, making cracks easy to occur and making it difficult to increase the size.

On the other hand, mesocarbon spherules with self-sintering properties solve the above problems and have a higher density and higher density compared to the conventional method of adding binder to aggregate coke or directly pulverizing heat-treated material It is a raw material that has great advantages in industrially producing strong carbon materials.

<Problems to be Solved by the Invention> By the way, carbon materials manufactured from mesocarbon spherules having an average particle size of 10 μm or more usually have somewhat large pores, and do not have perfect sealing properties against gas or liquid. It was impossible to use it as it is, for example, in mechanical carbon, which requires the following. In normal cases, impregnation with resin, etc. is implemented as a way to improve sealing performance to achieve impermeability, but impregnation with resin, etc. requires a lot of labor, and due to the heat resistance temperature of resins, it is not possible to use it. A major drawback was that the maximum temperature was about 150°C. Of course, it is possible to impregnate a carbon material obtained from mesocarbon spherules having self-sintering properties, but the same problems as above arise.

On the other hand, by controlling the heat treatment conditions such as tar pitch, which is the raw material for producing mesocarbon spherules, it is possible to directly
Although it is possible to produce mesocarbon spherules with a size of less than m, there is an economical problem in that the yield of mesocarbon spherules is usually extremely low at a few percent relative to the pitch of the raw material.

An object of the present invention is to provide an economically efficient method for producing a high-density carbon material with significantly improved sealing properties without using a binder.

<Means for Solving the Problems> In order to achieve the above object, according to the present invention, tar
After heat-treating pitches, mesocarbon spherules with self-sintering properties with an average particle size of 10 μm or more obtained by separating from the pitch matrix in the heat-treated pitch are finely pulverized to produce powder with an average particle size of 5 μm or less. Provided is a method for producing a high-density carbon material, characterized in that the powder is molded and fired without using a binder.

The present invention will be explained in more detail below.

The self-sintering mesocarbon spherules used in the present invention are made of tar pitch or petroleum heavy oil, for example,
The mesocarbon spherules (also called spherulites) that are generated in the pitch when heated at a temperature of 50 to 500°C are heat-treated during the pitch so that a portion of the pitch, which is a binder component, is uniformly dispersed on the surface. It is separated from
In manufacturing carbon materials, it is possible to mold, bake, and graphitize without using a binder.

As an example of a method for producing mencarbon spherules having self-sintering properties, the present applicant et al.
After the mesocarbon spherules formed in the pitch matrix as shown in No. 4 are separated in a solvent together with heavy components such as the β component (component insoluble in benzene and soluble in quinoline) in the pitch, they are separated in an inert atmosphere. at 200-500℃
There is a method of force-firing at a temperature of , but it is not limited to this method.

As a method for adjusting the sealing properties of carbon materials, that is, the pore distribution, it is well known that in general carbon material manufacturing methods, particle size adjustment of aggregate coke is extremely important. In other words, in order to produce a carbon material with a small average pore size and excellent sealing properties, it is preferable to use aggregate coke with as small a particle size as possible; As a result, pores are generated due to volatilization of the binder during firing of the molded body, so it is difficult to make the molded body dense and finely porous. However, in the case of mencarbon spherules having self-sintering properties, no pores are generated due to volatilization of the binder, so even if the average particle size is made smaller, the above problem does not occur.

Normally, the particle size control of mesocarbon spherules is determined by the heat treatment conditions of raw material pitches for producing mesocarbon spherules. That is, as conditions become more severe, such as raising the treatment temperature and lengthening the holding time during heat treatment, the particle size of the mesocarbon spherules increases and the yield also increases. but,
If the heat treatment conditions become too harsh, the mesocarbon spherules will coalesce and will no longer exist as a sphere, resulting in a decrease in the characteristics of the carbon material made from the mesocarbon spherules, such as strength, electrical resistivity, thermal expansion coefficient, etc. In addition to the loss of isotropy in physical properties, it is difficult to have strong self-sintering properties due to a relative decrease in heavy components such as β components in the heat-treated pitch, which is a binder component. Become. - On the other hand, when the particle size of the mesocarbon spherules is reduced by relaxing the heat treatment conditions, the yield of the mesocarbon spherules relative to the raw material pitch is greatly reduced. Because of this relationship, the average particle size of mesocarbon small spheres is usually controlled to about 10 to 20 μm.

Therefore, it has been discovered that a high-density carbon material with improved sealing properties can be easily produced by further pulverizing these 10-20 μm mesocarbon spherules.
In other words, mesocarbon spherules can be easily pulverized into ultrafine powder with an average particle size of 5 μm or less using, for example, a jet-type ultrafine pulverizer. It is not crushed into pieces, and can be crushed while retaining its spherical shape. Moreover, the self-sintering property became stronger compared to before milling, and as a result, densification and reduction of pore size were achieved due to grain refinement and increased self-sintering property. That is, in order to reduce the particle size of the mesocarbon spherules, it has become possible to produce a dense carbon material with a small pore size without reducing the yield by relaxing the heat treatment conditions for the raw material pitch.

Normally, the smaller the particle size of the mesocarbon spherules after pulverization, the better from the perspective of improving sealing performance, but from the viewpoint of pulverization efficiency, it is not preferable to make the particle size too small from an economic point of view.In general, pulverization to 5 μm or less is preferable. If this is done, the gas or liquid sealing performance required for Ia mechanical carbon can be ensured, although it depends on the thickness of the product.

In addition to the jet-type pulverizer mentioned above, the pulverizing method can be used as a commercially available ultra-fine pulverizer such as a micronizer, a micro-atomizer, a micron mill, a majac mill, a classification impact mill, or a liar mill. etc. can be used.

Mesocarbon small spherical powder with self-sintering properties that has been pulverized to have an average particle size of 5 μm or less is molded into a desired shape without using a binder, and fired by a conventional method.
A high-density carbon material can be obtained by further graphitizing the material if necessary.

<Example> The present invention will be specifically explained below based on Examples.

(Example 1) Mesocarbon small spheres (trade name: KMFC, manufactured by Kawasaki Steel Corporation) having an average particle diameter of 15.5 μI and having self-sintering properties were finely pulverized using a jet mill manufactured by Hosokawa Micron Corporation. The average particle size of the resulting finely pulverized product was 5.0 μm. The finely pulverized product was molded into a size of 80 mmφ x 30 mm at a molding pressure of 800 kg/cab'' without using a binder, and then fired and graphitized according to a conventional method.The firing temperature was 1000°C, and the heating rate was 10°C/hour. In addition, the graphitization temperature was 2500℃, and the temperature increase rate was from room temperature to 1000℃.
℃/1 hour, too~2500℃/4 hours.

The physical property values and pore distribution of the obtained graphite material are shown in Table 1 and FIG. 1, respectively.

(Example 2) The mesocarbon small spheres having self-sintering property and having an average particle size of 15.5 μm in Example 1 were pulverized to an average particle size of 3.3 μm using a jet mill manufactured by Hosokawa Micron Co., Ltd. The obtained finely pulverized product was treated in the same manner as in Example 1 without using a binder to obtain a graphite material. The physical properties and pore distribution of the graphite material are shown in Table 1 and FIG.

(Example 3) The self-sintering mesocarbon small spheres having an average particle size of 15.5 μI in Example 2 were pulverized to an average particle size of 1.5 μm using a jet mill manufactured by Hosokawa Micron Corporation. The obtained finely pulverized product was treated in the same manner as in Example 1 without using a binder to obtain a graphite material. The physical properties and pore distribution of the graphite material are shown in Table 1 and FIG.

(Comparative Example 1) The mesocarbon small spheres having self-sintering properties with an average particle size of 15.5 μm in Example 1 were molded, fired, and graphitized under the same conditions as in Example 1 without being pulverized. . The physical property values and pore distribution of the obtained graphite material are shown in Table 1 and FIG. 1, respectively.

The graphite materials obtained in Examples 1 to 3 all had higher density and extremely smaller pore diameters than the comparative examples, and were shown to be suitable for mechanical carbon where sealing performance is important. There is.

<Effects of the Invention> Since the present invention is configured as described above, a high-density carbon material with significantly improved sealing properties can be produced from mesocarbon small spheres having self-sintering properties without using a binder. can be manufactured.

The high-density carbon material obtained by the present invention can be used for electrical science such as electrodes for electrical discharge machining, for metallurgy such as crucibles and boat materials, etc.
Furthermore, it can be used for applications such as graphite for nuclear reactors, and especially carbon for machines that require sealing properties.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the pore distribution of a high-density carbon material. FIG, I S L 4-i heather (pm) Procedural supplementary text (spontaneous) July 10, 1999 1986 patent @ No. 119586 2, title of invention Method for manufacturing high-density carbon material 3, amendment Relationship with the case involving a person who does
3-2-2-2 Iwamoto-cho, Chiyoda-ku, Tokyo, Claims (1) A self-sintered product with an average particle size of 10 μm or more obtained by heat-treating tar pitch and separating it from the pitch matrix in the heat-treated pitch. A method for producing a high-density carbon material, which comprises finely pulverizing mencarbon small spheres having crystallization properties into a powder with an average particle size of 5 μm or less, molding the powder without using a binder, and firing the powder. . (2) The mesocarbon spherules having self-sintering properties are
A claim in which tar pitch or petroleum-based heavy oil is heat-treated at a temperature of 350 to 500°C and separated from the heat-treated pitch so that a portion of the pitch is uniformly dispersed on the surface of the resulting mesocarbon spherules. 1. The method for producing a high-density carbon material according to 1. (3) The mesocarbon spherules having self-sintering properties are
After solvent fractionation of the mesocarbon spherules formed in the pitch matrix along with the heavy components including the β component (component insoluble in benzene and soluble in quinoline) in the pitch, the mesocarbon spherules were heated at 200 to 500°C in an inert atmosphere. The method for producing a high-density carbon material according to claim 1, wherein the high-density carbon material is calcined at high temperature. (4) The production of the high-density carbon material according to claim 1, wherein the fine pulverization is performed using a jet-type pulverizer, a micronizer, a microatomizer, a micron mill, a Majac mill, a classification impact mill, or a sieve. Method. (5) Using a jet mill, mesocarbon small spheres having an average particle size of 15.5 μm and having self-sintering properties were formed with an average particle size of 5.5 μm.
The finely pulverized product was molded at a molding pressure of 800 kg/cm2 without using a binder, and then fired at a firing temperature of 1000°C and a temperature increase rate of 10°C/hour. Temperature rate room temperature to 1000°C/1 hour, 1000 to b 1 , 96g/cm', bending strength 1150kg/cm
', Compressive strength 2065kg/ca+2, Shore hardness C
I (,190, electrical resistivity 1520 μΩ-cm, average pore diameter 0.048 μm and total pore volume o, os9cc/g
A method for producing a high-density carbon material, characterized by obtaining a graphite material having physical properties. (6) Using a jet mill, mesocarbon small spheres with an average particle size of 15.5 μm and having self-sintering properties were formed with an average particle size of 3.5 μm.
The finely pulverized product was molded at a molding pressure of 800 kg/cm2 without using a binder, and then fired at a firing temperature of 1000°C and a heating rate of 10°C/hour. Temperature rate room temperature to 1000°C/1 hour, 1000 to b1, 98g/cm3. Bending strength 1230 kg/cm
2. Compressive strength 2140 kg/cI11', Shore hardness (H,) 93, electrical resistivity 1730 μΩ-cm, average pore diameter 0.034 μm and total pore amount 0.058 cc/g
A method for producing a high-density carbon material, characterized by obtaining a graphite material having physical properties. (7) Using a jet mill, mesocarbon small spheres with an average particle size of 15.5 μm and having self-sintering properties were produced with an average particle size of 1.5 μm.
The finely pulverized product was molded at a molding pressure of 800 kg/cm2 without using a binder, and then fired at a firing temperature of 1000°C and a heating rate of 10°C/hour. Temperature rate room temperature to 1000℃/1 hour, 1000 to b 2,01 g7cm'', bending strength 1250kg/cn+
2. Compressive strength 2120kg/cm', Shore hardness (H
, ) 98, a method for producing a high-density carbon material, characterized in that a graphite material having physical properties of an electrical resistivity of 1870 μΩ-cm, an average pore diameter of 0.025 μm, and a total pore amount of 0.051 cc/g is obtained.

Claims (1)

[Claims] (1) After heat-treating tar and pitch, mesocarbon spherules with an average particle size of 10 μm or more and having self-sintering properties are obtained by separating them from the pitch matrix in the heat-treated pitch, and are finely pulverized to obtain an average particle size of 10 μm or more. is a powder with a diameter of 5 μm or less,
A method for producing a high-density carbon material, which comprises molding and firing the powder without using a binder.