JPH04283293A - Preparation of coke for isotropic high-density carbon material - Google Patents

Abstract

PURPOSE:To obtain the title coke having a minute carbon structure in high yields by subjecting a mixture of a given heavy pitch with a carbonization assistant and/or carbonaceous particulates to a specific heat treatment. CONSTITUTION:100 pts.wt. heavy pitch containing 50wt.% or more of toluene- insolubles extracted and separated from pitch (e.g. coal tar pitch) is mixed with 1-30 pts.wt. carbonization assistant (e.g. dinitronaphthalene) and/or carbonaceous particulates (e.g. carbon black) excellent in compatibility with the heavy pitch. The mixture is treated at 300-500 deg.C in an inert gas atmosphere under atmospheric pressure.

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 coke for isotropic high-density carbon materials used as bearing materials for machines, electrodes for electric discharge machining, jig materials for semiconductor manufacturing, and the like. More specifically, the present invention relates to a method for producing high-performance isotropic high-density carbon material coke at a high yield by adding a small amount of carbonization aid or carbonaceous fine powder.

0002

[Prior Art] Conventionally, a method for producing coke as a raw material for isotropic carbon materials involves converting coal-based pitch or petroleum-based pitch into raw coke in a room furnace or delayed coker, and then calcining this in a rotary kiln or the like at a temperature of 1,400°C or higher. It was fried coke. To manufacture isotropic high-density graphite material, finely pulverized calcined coke is used as aggregate, and a binder such as binder pitch is added to it.
A common method is to knead, cool, re-pulverize, mold, and fire, and if necessary, impregnate the pores with impregnated pitch, re-fire, and then graphitize.

[0003] Normally, this impregnation and re-firing process must be repeated several times. Therefore, in recent years, compared to these conventional methods,
Attempts have been made to produce raw material coke for carbon materials that can save labor and energy by omitting a series of steps including addition of a binder, kneading, re-grinding, impregnation, and re-calcination.

For example, (1) Japanese Patent Application Laid-Open No. 59-207822
In the publication, a method is proposed for producing a raw material for high-density carbon material by adding a nitrating agent such as concentrated nitric acid to coal tar and then heat-treating it at 400 to 530°C under reduced pressure.
(2) In JP-A No. 63-242911,
After mixing carbon powder and a nitrating agent with heavy oil such as coal tar, heat treatment is performed at 300 to 500°C under reduced pressure,
Methods for producing raw materials for high-density carbon materials have been proposed.

[0005] The high-density graphite material obtained by these methods is
Both methods are superior in that they can be manufactured by molding, carbonization, and graphitization without adding a binder, but in method (1) above, an aqueous solution such as concentrated nitric acid is added to the hydrophobic pitch, which separates it into two phases. However, there is a problem that uniform dispersion is difficult. In addition, in methods (1) and (2) above, the pressure is reduced during heat treatment, so even if a nitrating agent is added, the raw material for carbon material (
The yield of coke) is extremely low. In addition, in the latter stages of heat treatment, the viscosity of the pitch increases and foaming becomes intense due to the reduced pressure, which can cause operational troubles, and the coke itself becomes porous, increasing the density of the compact. The problem is that there is no.

[0006]

[Problems to be Solved by the Invention] The main object of the present invention is to provide a method for producing raw material heavy pitch that can be carbonized at a relatively low temperature even under normal pressure and that can make the carbon structure after carbonization fine. purpose.

[0007]

[Means for Solving the Problems] As a result of intensive research in order to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by adjusting in advance the toluene-insoluble content of raw pitch to 50% by weight or more. They found a solution to the problem and completed the present invention.

That is, the present invention provides for 100 parts by weight of heavy pitch containing 50% by weight or more of toluene-insoluble matter extracted and separated from pitch, a carbonization aid having excellent compatibility with the heavy pitch, and/or 1 to 30 parts by weight of carbonaceous fine powder is mixed, and the mixture is heated to 300 to 300 parts by weight under normal pressure and inert gas atmosphere.
This is a method for producing isotropic high-density carbon material coke, which is characterized by heat treatment in a temperature range of 500°C.

The present invention will be explained in detail below. Although any pitch can be used as the raw material, pitch with a softening point of 100° C. or lower obtained by distilling coal tar produced as a by-product during coal carbonization, particularly soft pitch with a softening point of 70° C. or lower, is suitable.

[0010] The extraction and separation method for toluene-insoluble matter (benzole-insoluble matter also has the same characteristic values, only the test solvent is different) is not particularly limited, but coal tar pitch can be thermally modified or thermally modified. Heavy pitch containing 50% by weight or more of toluene-insoluble matter is separated without any waste. Note that the toluene-insoluble content in the present invention includes quinoline-insoluble content (QI).
may be included or removed.

As a more preferable extraction separation method, the present applicant has previously disclosed Japanese Patent Application Laid-open No. 112687/1983 and Japanese Patent Application Laid-open No. 63-112687.
As proposed in Publication No. 4-69692, coal tar pitch is phase-separated into a low specific gravity liquid and a high specific gravity liquid mainly composed of ash in a first separation zone under the supercritical state of the solvent together with an aromatic hydrocarbon solvent. Next, the low-density liquid is phase-separated in a second separation zone into a low-density liquid and a high-density liquid in which toluene-insoluble components are concentrated under a supercritical state using a solvent different from that in the first separation zone, to obtain a high-density liquid phase. By removing the solvent from
Heavy oil containing 0.1% by weight or less of ash and 50% by weight or more of toluene-insoluble components can be easily obtained. Since ash becomes an impurity in the product carbon material and lowers the added value, it is preferable to remove it as much as possible.

[0012] The carbonization aid has excellent compatibility with the raw material heavy oil, and by adding a small amount, the radical reactivity during heating polymerization can be significantly improved, and the carbon structure after carbonization is Any material can be used as long as it can be miniaturized. For example, dinitronaphthalene, dinitrobenzene, nitrobenzene, nitroanthraquinone, naphthoquinone, nitroaniline sulfonic acid, divinylbenzene and their derivatives, or the above compounds, which are aromatic hydrocarbons with nitro, carbonyl, sulfone, and vinyl groups introduced. Mixtures and the like can be mentioned.

[0013] Carbonaceous fine powder includes amorphous carbon, glassy carbon fine powder, non-graphitizable carbonaceous fine powder such as carbon black, natural graphite, artificial graphite, needle coke, and raw coke (green coke) of needle coke. Easily graphitizable carbonaceous fine powder such as or a mixture thereof can be used. The purpose of adding these carbonaceous fine powders is to create a carbon structure suitable for an isotropic carbon material, and therefore, the finer the particle size of the fine powders, the better.

[0014] The present inventor investigated the relationship between the properties of the heavy pitch used as a raw material, the amount of carbonization aid and/or carbonaceous fine powder added, and the carbon structure after carbonization, and found that the heavy pitch used as a raw material It has been found that as the amount of toluene-insoluble components in pitch increases, the carbon structure after carbonization becomes finer by adding a small amount of carbonization aid or carbonaceous fine powder. The reason for this is that the higher the amount of toluene-insoluble components in heavy pitch, the faster the rate of generation, growth, and coalescence of mesophases associated with the polycondensation reaction of heavy pitch, and the faster the rate of increase in viscosity. It is thought that this makes it possible to refine the carbon structure because this is less likely to occur.

[0015] The amount of carbonization aid and/or carbonaceous fine powder to be added is 1 to 30 parts by weight, more preferably 5 to 25 parts by weight, per 100 parts by weight of heavy oil. A carbon structure suitable for carbon materials can be obtained, and high-performance isotropic high-density carbon materials can be manufactured. Addition and kneading of the carbonization aid and/or carbonaceous fine powder may be performed directly to heavy oil, but if the heavy oil has a high softening point, it may be added and kneaded after being dissolved in a highly volatile solvent. By doing so, uniform dispersion is possible.

[0016] By heat-treating this mixture at 300 to 500°C under normal pressure and an inert gas atmosphere, coke for isotropic high-density carbon material can be produced. Since this mixture has high reactivity, it can be carbonized at a lower temperature than normal raw material pitch that does not contain concentrated toluene-insoluble matter, resulting in cost reduction. Furthermore, since carbonization is carried out under normal pressure, the yield is high and troubles due to foaming do not occur. The reason for conducting the reaction under an inert atmosphere is to prevent oxidation of heavy pitch, and nitrogen, argon, etc. can be used as the atmospheric gas.

[0017] The isotropic carbon material coke obtained by the method of the present invention can be molded without using binder components such as binder pitch or phenol resin. Moreover, any method such as a normal mold press or a rubber press can be adopted as a molding method, and the molded body before carbonization and graphitization has sufficient strength to withstand handling. Then, the molded body can be carbonized and further graphitized into a graphite material by heating in an inert gas or coke powder according to a conventional method.

[0018]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

(Examples 1 and 2) Coal tar pitch (toluene-insoluble component 6.0% by weight, ash content 0.02% by weight) was extracted using toluene as an extraction solvent, and 50kg was heated at 340°C, which is the supercritical state of toluene. /cm2, toluene insoluble content concentrated heavy oil (toluene insoluble content 90.3% by weight, ash content 0.07% by weight) was extracted and separated. After coarsely pulverizing this heavy oil, it was dissolved in a solvent (tetrahydrofuran), and dinitronaphthalene was added as a carbonization aid in the amount shown in Table 1. After the solvent was volatilized and removed at normal pressure and 100° C., heat treatment was performed under the conditions shown in Table 1 to obtain coke for carbon material. This coke was pulverized to an average particle size of 5 μm and 1.0 t/cm2
CIP (hydraulic isostatic pressing) molding was performed at a pressure of 60 m.
A molded body of mφ×120 mm was created. Next, this molded body was fired at 950°C and further graphitized at 2500°C. Table 2 shows the physical properties of the graphitized molded product obtained.

(Comparative Examples 1 and 2) After mixing the raw material coal tar pitch used in Examples 1 and 2 (without extracting and concentrating toluene-insoluble components) with a carbonization aid, the same evaluation as in Examples 1 and 2 was carried out. I did it. Table 2 shows the physical properties of the graphitized molded product obtained.
Shown below.

(Example 3) In Examples 1 and 2, carbon black (FEF) was mixed in the amount shown in Table 1 instead of the carbonization aid. Table 2 shows the physical properties of the graphitized molded product obtained. (Example 4) In Examples 1 and 2, dinitronaphthalene and carbon black (FEF) were mixed in the amounts shown in Table 1. Table 2 shows the physical properties of the graphitized molded product obtained.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

Effects of the Invention: As is clear from a comparison of Examples 1, 2, 3, and 4 with Comparative Examples 1 and 2, by using the heavy pitch containing concentrated toluene-insoluble matter of the present invention, a small amount of It can be seen that by adding carbonization aids etc., it is possible to refine the carbon structure and achieve a high yield. Furthermore, by using this heavy pitch, heat treatment can be completed at low temperatures and in a short time. Further, by comparing the physical property values of the obtained graphite materials, it is clear that a high-performance isotropic high-density carbon material can be obtained by employing the method of the present invention.

Claims (1)

[Claims] Claim 1: For 100 parts by weight of a heavy pitch containing 50% by weight or more of toluene insoluble matter extracted and separated from the pitch, a carbonization aid having excellent compatibility with the heavy pitch and/or a carbonaceous material is added. A method for producing coke for isotropic high-density carbon material, which comprises mixing 1 to 30 parts by weight of fine powder and heat-treating the mixture at a temperature range of 300 to 500° C. under normal pressure and an inert gas atmosphere.