KR920005408B1 - Preparing method of carbon particle - Google Patents

Abstract

A self sintering carbon powder is produced by (1) making anisotropic liquid crystal pitch having more than 95 wt.% of anisotropic ration and less than 60 wt.% of insolubile quinoline, by heat treating coal tar and heavy oil or their residual oil in inert gas atmosphere of 350-500 deg.C, (2) making the above anisotropic liquid crystal pitch in to solution with 0.1-80 wt.% of pitch concetration using quinoline, (3) dispersing the solution with low grade alcohol (added emulsifying agent more than 0.01 wt.%) or mixed solvent of distilled water and low grade alcohol, (4) separating the particle by filtering dispersed solution, and (5) insolubilizing the particle in oxidizing atmosphere of 200-350 deg.C or nitrate solution of more than 0.1N, for more than 10 min.

Description

Method for producing self-sintering carbon particles

1 is a texture photograph of an anisotropic liquid crystal pitch having an anisotropy ratio of 95% or more used as a raw material of the present invention.

2 is a graph showing the solubility of the front anisotropic liquid crystal pitch of FIG.

3 is a scanning electron micrograph of the self-sintering carbon particles prepared by the present invention and the comparative example.

4 is a transmission electron micrograph of the invention 1 in FIG.

5 is a scanning electron micrograph and a polarization micrograph of a crushed surface of a high-density carbon material manufactured by molding and carbonizing the self-sintering carbon particles prepared according to the present invention.

The present invention relates to a method for producing self-sintering carbon particles, which is a raw material for producing a carbon molded article having high strength and high density, using coal tar and petroleum heavy oil or residues thereof.

Generally, self-sintering carbon particles which are raw materials for carbon moldings are produced by 1) crushing raw coke produced in Delayed Coker from several microns to several hundred microns (Japanese Patent Application No. 61-24326, Carbon No.109). (1982), 41), 2) Method of separating and extracting carbonaceous anisotropic liquid crystal spheres having a diameter of about 10 μm during heat treatment of pitch with a solvent (Japanese Patent Publication No. 53-4016) or 3) 350 The pitch produced by heat treatment at a temperature of -500 ° C has been manufactured by a method such as extracting and removing soluble components using a solvent and then pulverizing them (Japanese Patent Application No. 63-205391). In the case of 1), raw coke used as a raw material should be crushed to a particle size of about 10 microns in order to be used as a raw material of high density carbon material, which requires a long time grinding process.

In addition, in order to achieve high density (density of 1.7 g / cm ³ or more at 2800 ° C. heat treatment), the press molding carbonization method is essential, and if the press carbonization method is not used, there is a problem of using a sintering aid of 1 wt% or more. Not only does it take a long time to extract the solvent, but also has a problem that the yield is 40 wt% or less, and in the case of 3), it has the problems of 1) and 2) at the same time. Accordingly, the present invention provides an improved method for producing carbon particles having an input of 10 microns or less in a yield of 95 wt% or more without producing long-term grinding and solvent extraction treatment in preparing self-sintering carbon particles which are raw materials of a high density carbon material. The purpose is to provide.

Hereinafter, the present invention will be described in detail. The present invention comprises the steps of heat-treating coal tar and petroleum-based heavy oil or residues thereof in an inert atmosphere of 350-500 ℃ to produce an anisotropic liquid crystal pitch of 95% or more of the fire rate; Preparing the anisotropic liquid crystal pitch to a solution having a pitch concentration of 0.1-80 wt% using quinoline; Dispersing the solution using a lower alcohol having 1 to 4% by weight of emulsifier or a mixed solvent of distilled water and lower alcohol as a dispersion medium; Filtering the dispersed solution to separate the particles; And insolubilizing the separated particles in an oxidizing atmosphere of 200-350 ° C. or a nitric acid solution having a concentration of 0.1 normal (0.1 N) or more for 10 minutes or more. It will be described in detail as follows.

The raw material used in the present invention is an anisotropic liquid crystal pitch of 95% or more of anisotropy formed by heat-treating coal tar and petroleum heavy oil or residues thereof in an inert atmosphere of 350 ° C-500 ° C, which has a QI (Quinoline Insoluble) content of 60 wt% or less It is preferable that it is 40 wt% or less, Furthermore, it is preferable that melting | fusing point is 340 degrees C or less, and also 300 degrees C or less.

The anisotropic liquid crystal pitch was quilled using quinoline, and then stirred at a temperature of 90 ° C. or lower to remove the residue to prepare a solution of 0.1 wt% or more. The medium for dispersing the solution is preferably a lower alcohol having 1 to 4 carbon atoms, or a mixed solvent of these and distilled water. In the case of the mixed solvent, the volume fraction of water to alcohol is preferably 50v% or less. In addition, it is preferable to add 0.01 wt% or more of an emulsifier to the medium, and Triton X-100 or P.V.A may be used. In the process of dispersing the solution in the medium, it is preferable to disperse and disperse at a rate of 0.1-100 ml / sec per 1000 ml of medium while maintaining a stirring speed of 300 rpm or more in a conventional emulsion stirring system, and the stirring time is such that the dropping of the solution is completed. After 5 minutes or more, it is preferable, and after completion of stirring, the particles are separated by filtration. In order to dissolve the separated particles, it is preferable to stir for 10 minutes or more in a nitric acid solution of 0.1 N or more in a range of 200-350 ° C. under an air atmosphere.

Hereinafter, the reason which limited the substance and conditions used by this invention is demonstrated. When the anisotropic liquid crystal pitch is used as a raw material, since the melting point increases as the QI content increases, it is preferable to use an anisotropic liquid crystal pitch having a melting point of 340 ° C. or less, and since QI inhibits yield decrease and dispersion of particles, In order to prevent this, anisotropic liquid crystal pitch having a QI content of 60 wt% or less, and more preferably 40 wt% or less is preferable. The quinoline solution of anisotropic pitch is effective to use at the concentration of 0.1wt% -80wt%, because the production yield is low when it is below 01wt%, and when it is above 80wt%, the excessive viscosity in the medium due to the rapid increase of the solution viscosity This is because a large amount is generated.

The quinoline solution of anisotropic pitch is preferably instilled at a rate of 0.1-100ml / sec per 1000ml of medium because the production time is long when the production time is 0.1ml / sec or less, and condensation is easily formed in the medium when 100ml / ch or more. Because.

The surfactant (emulsifier) is preferably added at a concentration of 0.01wt% or more in the medium, because when the concentration is less than 0.01wt%, a large amount of excess condensate of 10 microns or more is formed in the medium, resulting in lower overall yield and particle size distribution. This is because it causes the unevenness. The dissolution of the produced particles is preferably carried out for 10 minutes or more in a temperature range of 200-350 ° C. in an oxidizing atmosphere during heat treatment, and in the case of 10 minutes or less, insolubilization is not completed, which causes melting during carbonization of the molded product. . In the case of insolubilization using nitric acid, the concentration of the nitric acid solution is preferably 0.1N or more, and in the case of 0.1N or less, it takes a long time for the incompatibility treatment. The present invention will be described in detail through examples.

EXAMPLE

In this example, an anisotropic liquid crystal pitch having the solubility curve characteristics of the structure of FIG. 1 and FIG. 1 and FIG. 1 prepared by treating heavy oil in a temperature range of 350-500 ° C. was used.

TABLE 1

Invention Example 1

The pitch was pulverized to 80 mesh or less, powdered, quinoline was added at a powder / solvent ratio (g / ml) to 1/10, stirred at 90 ° C. for 60 minutes, and filtered through a 120 mesh filter heated at 90 ° C. Prepare about 15 wt% quinoline solution (hereinafter abbreviated to 15% QSp). At this time, the production yield of QSp was 95 wt% or more from the pitch.

Thereafter, 500 ml of a medium mixed with ethyl alcohol and middle water at 60:40 (vol / vol%) was added to a stirring reaction apparatus, and then, 1 ml of Triton X-100 was added thereto, and the temperature was raised to 50 ° C. while stirring for 10 minutes. While maintaining the temperature of the dispersion medium at 50 ° C., the rotation speed of the stirrer was fixed at about 1000 rpm, and the QSp solution was added dropwise at a rate of 100 ml / min, followed by dispersion reaction for 10 minutes. After the reaction time had elapsed for 10 minutes, the dispersed solids were filtered through a filtration device having a maximum pore size of 0.8 μm, followed by impregnation for 10 minutes to prepare carbon particles. The air flow rate was 6.67 ml / g · sec and the temperature increase rate up to 300 ° C. was 5 ° C./min.

The self-sintering carbon particles prepared according to Example 1 were aggregates of fine particles having a size of 100 nm or less during TEM observation, and the size of each aggregate did not exceed 10 μm in average diameter. The particle yield after dispersion was 98 wt% or more, and the specific surface area measured by the BET method was 28 m ² / g, and a small particle diameter and a large specific surface area were obtained in a yield of 95 wt% or more. Scanning electron micrographs and transmission electron micrographs of self-sintering carbon particles prepared according to Inventive Example 1 are shown in FIGS. 3A and 4, respectively.

Invention Example 2

The dispersed solid prepared in the same manner as in Example 1 was immersed in 20% nitric acid solution, stirred for 10 minutes, infusible, and then filtered and dried to prepare self-forming carbon particles. A scanning electron micrograph of the self-sintering carbon particles prepared according to Inventive Example 2 is shown in FIG. 3 (b). As shown in FIG. 3 (b), the same phenomenon as in Inventive Example 1 is shown.

Invention Example 3

Self-sintering carbon particles were prepared in the same manner as inventive example 1 at a reaction temperature of 50 ° C using 500 ml of methyl alcohol containing 1 ml of Triton X-100 as a 15%, QSp solution prepared in the same manner as inventive example 1. .

Particle size of the self-sintering carbon particles obtained in Example 3 was a part of the aggregate having a diameter of 100nm or more. Scanning electron micrographs of the self-sintering carbon particles obtained in Example 3 are shown in FIG.

[Comparative Example]

The 15% QSP solution prepared in the same manner as inventive example 1 was prepared by using 500 ml of distilled water with a nonconductivity of 10 ⁶ ohm / cm or more containing 1 ml of Triton X-100 in the same manner as inventive example 1 at a reaction temperature of 90 ° C. Sinterable carbon particles were prepared. Scanning electron micrographs of the self-sintering carbon particles prepared in Comparative Example 4 are shown in FIG.

As shown in (d) of FIG. 3, the comparative example showed a finer than the invention examples 1-3, but showed a solidified bulk, and had to be crushed and used again after infusible treatment. Using the self-sintering carbon particles prepared according to Inventive Example (1-3) and Comparative Example as raw materials, carbon molded bodies were prepared under the conditions as shown in Table 2 below, and their properties were shown in Table 2 below. Figure 5 shows the scanning micrographs of the fracture surfaces of the inventions (A, B) and the tissue photographs under the polarization microscope in the molded bodies of Table 2 below.

TABLE 2

As shown in Table 2, the invention was molded at 300kgf / cm ² molding pressure at room temperature using the self-sintering carbon particles prepared according to the invention example (1-3) and carbonized at 950 ℃ (A, CD ) is 1.24gm / cm ³ represents the above bulk density and 652kg / cm ² or more compression strength, the present body (B) of molding and the molding pressure to 2000kgf / cm ² is the bulk density of 1.76gm / cm ² compression strength It can be seen that it is 795kg / cm ² .

On the other hand, the comparative body prepared by the comparative example was destroyed in carbonization. 5 (a) and (b) showing the scanning micrographs of the crushed surfaces of the invention A and the tissue photographs under the polarization microscope, respectively, and the scanning micrographs and the polarized microscopes of the crushed surfaces of the invention B, respectively. As shown in Figure 5 (c) and (d) showing the tissue photograph, it can be seen that the invention A and B is isotropic tissue.

Based on these results, the carbon particles produced in the present invention have been proved to be self-sintering carbon particles capable of producing high density carbon materials without grinding and other sintering aids, and have high yields of 95 wt% or more from pitch raw materials. It can be seen that can be prepared.

Claims (2)

Heat treating coal tar and petroleum heavy oil or residues thereof in an inert atmosphere at 350-500 ° C. to produce an anisotropic liquid crystal pitch having a quinoline insoluble content of 60 wt% or less and an anisotropic rate of 95 wt% or more; Preparing the anisotropic liquid crystal pitch to a solution having a pitch concentration of 0.1-80 wt% using quinoline; Dispersing the solution using a lower alcohol having 1 to 4 wt% of emulsifier or a mixed solvent of distilled water and lower alcohol as a dispersion medium; Filtering the dispersed solution to separate the particles; And dissolving the separated particles in an oxidizing atmosphere of 200-350 ° C. or a nitric acid solution having a concentration of at least 0.1 normal (0.1 N) for at least 10 minutes. The method of producing self-sintering carbon particles according to claim 1, wherein the dispersion medium has a volume fraction of distilled water of 50% or more with respect to alcohol when using a mixed solvent.

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