KR920005407B1 - Preparing method of carbon products - Google Patents

Abstract

The carbon molded body is produced by (1) making an anisotropic liquid crystal pitch having more than 85 vol% of anisotropic ratio and less than 340 deg.C of melting temperature, by heat treating coal tar and heavy oil or their residual oil in inert gas at mosphere of 350-500 deg.C, (2) making long fiber by spinning at less than 30 μm diameter, (3) making a stabilized fiber by mixing the long fiber with nitric acid water solution of the concentration of 5-63 % for more than 1 min, and acid treating it to less than 5 wt.% of oxygen content, (4) making milled fiber less than 1 mm of its length by crushing the stabilized fiber, and (5) mixing the milled fiber with self sintering carbon powder having 15 wt.% of volatile matter and less than 10 μm diameter.

Description

Method for producing carbon molded body using stabilized fiber

1 is a scanning electron micrograph showing an example of a stabilizing fiber used in the present invention.

2 is a scanning electron micrograph showing an example of carbon particles used as a raw material in the present invention.

3 is a scanning electron micrograph of a molded article crushed surface prepared according to the present invention.

4 is a polarizing microscope tissue photograph of a molded article prepared according to the present invention.

Figure 5 is a photograph showing the appearance after carbonization of the molded article produced according to the present invention.

The present invention is a method for producing a carbon molded article that is useful for the machine parts, electrical components and chemical device structure, and more specifically, to produce a stabilizing fiber of less than 1mm of fiber length capable of self-sintering using pitch as a raw material, The present invention relates to a method for producing a carbon molded article having high strength, density and carbonization yield.

In general, the carbon molded body (1) a method of producing by pressurizing, molding and carbonizing natural or artificial graphite with a caking additive (Japanese Patent Application No. 61-24326), or mesocarbon microbeads and self-sintering carbon particles, etc. Although there is a method of molding and carbonizing (Japanese Patent Laid-Open No. 53-4016, Carbon No. 109 (1982), 41), etc., no method showing the reinforcing effect on the matrix using stabilizing fibers has been proposed.

The present invention has a self-sintering property, and the acid-treated stabilizing fiber of 1 mm or less of fiber length treated with self-sintering carbon particles is molded and carbonized so as to increase the oxygen content by 5% by weight or less, thereby reinforcing the fiber of the existing carbon molded body. By giving a, to prepare a carbon molded body that brings an increase in compressive strength of 100kg / cm ² or more and an increase in carbonization yield of 5% or more, the purpose is.

Hereinafter, the present invention will be described in detail.

The present invention comprises the steps of heat treating coal tar and heavy oil or residues thereof under an inert atmosphere of 350-500 ° C. to produce an anisotropic liquid crystal pitch having an anisotropy ratio of 85 vol% or more and a melting point of 340 ° C. or less; Spinning the pitch to a diameter of 30 µm or less to form long fibers; A step of stirring the long fiber for 1 minute or more using an aqueous nitric acid solution at a concentration of 5-63% to produce an stabilized fiber by acid treatment to increase the oxygen content to 5% by weight or less; Grinding the stabilizing fibers to produce milled fibers having a fiber length of 1 mm or less; It relates to a method for producing a carbon molded body using a stabilized fiber comprising the step of kneading the milled fiber with self-sintering carbon particles having a volatile content of 15% by weight and a particle diameter of 10㎛ or less in a conventional manner.

Hereinafter, the reasons for limiting the materials and conditions used in the present invention will be described.

The pitch used as a raw material in the present invention should be 85 vol% or more of anisotropy and 340 ° C. or lower, and it is difficult to melt spinning the pitch fiber when the fire rate is 85 vol% or less, and the spinning temperature is high when the melting point is 340 ° C. or higher. This is because stable fiber spinning is impossible. In addition, when the concentration of the nitric acid solution is 5% or less during the oxidation treatment of the fiber, a long time is required for the oxidation treatment, and when 63% or more, the fiber is destroyed during the stabilization treatment and the physical properties of the fiber are sharply degraded. In case of stirring for 1 minute or less, sufficient stabilization does not occur. Therefore, the mixture must be stirred for 1 minute or more, and the increase in oxygen content of the stabilized fiber should be 2% by weight or less. This is because the self-sintering property is lost and the reinforcing effect is inhibited in the production of the molded product. When the fiber length is 1 mm or more, the molded product loses the mechanical isotropy. . In addition, when the fiber diameter is more than 30㎛ requires a long time for the stabilization treatment, the fiber diameter is preferably 30㎛ or less because the fiber easily loses self-sintering due to excessive oxidation of the surface.

Preferably, the molding is performed at a molding pressure of 200-2000 kg / cm ² , and the carbonization treatment is performed at about 750 ° C. or more, preferably about 950 ° C.

Carbon molded article prepared according to the present invention by the reinforcing effect of the fiber has a compressive strength of 100kg / cm ² or more, the carbonization yield is increased by 5% by weight or more.

Hereinafter, the present invention will be described in detail through examples.

EXAMPLE

In this embodiment, an anisotropic liquid crystal pitch having the characteristics shown in Table 1 below, prepared by treating heavy oil at a temperature in the range of 350 to 500 ° C. was used.

TABLE 1

Invention Example 1

Using the pitch fiber spinning apparatus, the anisotropic liquid crystal pitch was spun at a speed of 500 m / min at a spinning temperature of 360 ° C. under an inert atmosphere, and 5 g of pitch fibers having a fiber diameter of 20 µm were immersed in an aqueous 20% nitric acid solution. After stirring for 4 minutes at a temperature of 50 ° C., 5.09 g of stabilized fibers having a fiber length of 1 cm or less having a self-sintering property of increasing oxygen content of 1.8 wt% were prepared, and scanning electron micrographs of the stabilized fibers were shown in FIG. Is shown.

After grinding the stabilized fiber to 1 mm or less in fiber length, it was kneaded with 1: 1 (wt / wt) and self-sintering carbon particles as shown in FIG. 2 having a volatile matter content of 15% by weight and a particle diameter of 10 µm or less, and then at room temperature. A molded article was manufactured at a pressure of 200 kg / cm ² , and carbonized at 950 ° C. for 1 hour at a temperature increase rate of 5 ° C./min in an inert atmosphere to prepare a molded article.

The resulting carbon molded body had an apparent density of 1.30 g / cm ³ and a carbonization yield of 89.2 wt%. The compressive strength measured using a universal testing machine (Instron 4200 Series) was 710 kg / cm ² (head speed: 0.5 mm / min). It was.

Scanning electron micrographs of the fractured surface of the carbon molded article prepared in Example 1, tissue photographs observed with a polarizing microscope, and the carbon molded article outlines are shown in FIGS. 3 (a), 4 (a), and 5, respectively. It was.

As shown in FIG. 3 (a), Inventive Example 1 shows that the self-sintering stabilizing fiber has a reinforcing effect on the molded body during the carbonization process by sintering the surface of the fiber and the carbon particles. As shown in a), the optical structure of the stabilizing fiber was completely converted into anisotropic tissue by 950 ° C. heat treatment, and the fibers were disorderly oriented in the fiber direction in the isotropic tissue of the matrix.

Invention Example 2

The self-sintering stabilizing fibers having a fiber length of 1 mm or less prepared in the same manner as in Inventive Example 1 were 1: 1 weight (wt / wt) with the self-sintering carbon particles shown in FIG. After kneading, the mixture was molded at a pressure of 2000 kg / cm ² at room temperature, and carbonized in the same manner as in Inventive Example 1 to prepare a carbon molded body.

The resulting carbon molded body had an apparent density of 1.67 g / cm ³ and a carbonization yield of 89.9 wt%, and a compressive strength of 780 kg / cm ² measured by the same method as inventive example 1.

Scanning electron micrographs of the crushed surfaces of the carbon formed bodies prepared according to Example 2, tissue photographs and shapes observed with a polarization microscope are shown in FIGS. 3B, 4B, and 5.

As shown in (b) of FIG. 3 and (b) of FIG. 4, the fibers were well fused with the matrix and randomly circumvented, and the structure of the matrix was much denser than that of Inventive Example 1.

[Comparative Example]

Carbon moldings were prepared by shaping and carbonizing in the same manner as in Inventive Example 1 using only 15 wt% of volatile matter used in Inventive Example 1 and self-sintering carbon particles having an input of 10 μm or less.

The resulting carbon compact had an apparent density of 1.35 g / cm ³ and a carbonization yield of 84.2 wt%, and a compressive strength of 590 kg / cm ² measured by the same method as inventive example 1.

The scanning electron micrograph of the crushed surface of the carbon molded body manufactured by the comparative example and the tissue photograph observed with the polarization microscope are shown to (c) of FIG. 3, and (c) of FIG.

The molded article manufacturing conditions and physical properties of Inventive Examples 1 and 2 and Comparative Examples are shown in Table 2 below.

TABLE 2

As shown in Inventive Examples 1 and 2 and the comparative example, the present invention is 100kg by reinforcing effect of the fiber by kneading the carbon fiber 1mm or less stabilizing fiber having a self-sintering property with the carbon particles, and carbonized to produce a carbon molded body It can be seen that the compressive strength can be increased more than / cm ² , and the carbonization yield is also increased by more than 5% by weight.

In addition, since the stabilization fiber is used, it has the reinforcing effect of the carbon fiber without carbonization treatment, thereby reducing the power and process, and unlike carbon fiber, excellent adhesion to the matrix of the fiber without the surface treatment of the fiber It can be seen that the production of the molded body is possible.

Claims (1)

Heat treating coal tar and heavy oil or residues thereof in an inert atmosphere at 350-500 ° C. to produce an anisotropic liquid crystal pitch having an anisotropy rate of 85 vol% or more and a melting point of 340 ° C. or less; Spinning the pitch to a diameter of 30 µm or less to form long fibers; Preparing the stabilizing fiber by acid-treating the long fiber for 1 minute or more using an aqueous solution of nitric acid at a concentration of 5-63% to increase the oxygen content to 5% by weight or less; Grinding the stabilized fibers to produce milled fibers having a fiber length of 1 mm or less; And kneading the milled fiber with self-sintering carbon particles having a particle size of 15% by weight or less and having a particle size of 10 µm or less, and molding and carbonizing the same by a conventional method.

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