KR910007569B1 - Method of preparing a carbon articles - Google Patents

Abstract

A carbon-molded article is produced by crushing pitches having at least 300 deg.C softening point to 250 μm particle size or less, dipping the powders in 0.1-14N nitric acid soln., immobilizing and surface-treating them by heating at 40-60 deg.C and agitating for 30-180 min, washing and drying them, molding them at 50-300 kgf/cm2, and calcining them under the inert gas atmosphere at 900 deg.C or more. The high strength and high density article is used in the mfr. of mechanical- and electricparts.

Description

Manufacturing method of carbon molded body

1 is a graph showing IR measurement results of raw materials before and after nitric acid treatment.

2 is an external shape of the carbon molded article produced by the present invention.

3 is an electron micrograph of the fracture surface of the molded body.

The present invention relates to a method for manufacturing high-density and high-density carbon molded parts used in machinery parts, electrical parts, chemical device structures, etc. using pitch as a raw material, and more particularly, softening point without regard to optical structure. The present invention relates to a method for producing a high strength and high density carbon molded body using pitches of 300 ° C or more as raw materials.

Carbon moldings are useful in places where existing materials are difficult to use due to their carbon-specific properties, such as mechanical parts, electrical parts, and chemical device structures.

The carbon molded body has been used as a raw material itself by kneading natural graphite, artificial graphite, and the like with a binder, followed by compression molding, calcining, and graphitization.

However, this method contains a lot of pores as the volatiles are removed in the binder portion during firing, and the portion having such pores acts as a defect and causes a decrease in strength, so that the pores are used again to reinforce it. Impregnation and recarbonization processes are necessary for filling. This process has to be repeated several times and therefore requires considerable power and expense.

In order to improve this, a method of preparing a carbon molded body using only carbon particles without using a caking agent has been proposed. In particular, a) a carbon material is prepared by separating the mesophase microparticles formed after heat treatment of a pitch and pressing them. Method (Japanese Patent Laid-Open Publication No. 53-4016), b) A method for producing a carbon material after press molding using mesocarbon microbeads prepared in the same manner as a) method using stearic acid as a caking agent (Japan 53-4017), c) A meso face pitch containing 95% or more of mesofaces is pulverized with an organic solvent in a ball mill to form particles of 10 μm or less, which are insoluble as air to liquid oxides. (2) A method for pressing and molding (EP 283211 A2), d) A method of pressing and crushing the fresh coke to 100 mesh or less, adding 1-5 wt% of pitch as a caking agent, and then press molding (Japanese Patent Laid-Open No. 61-61). 24362) and e) fresh coke A method of finely pulverizing 1-5 μm and then molding it under high temperature and high pressure (carbon No. 109p. 41, 1982) has been proposed. However, the method a) has a low yield of microspheres and is even difficult to separate the globules produced in the pitch, and the process is not only complicated but also requires a long time to manufacture.

In the method of b), the use of caking additives may cause porosity due to volatility and the like, and as in a), the production of microspheres is required. Unlike the method of a), the method of c) differs from the method of a) in that the yield is improved. However, since the particles must be pulverized finely to 10 μm or less, it requires a lot of power consumption, and the pitch of the raw material contains 95% or more of mesophase. There is a limitation of pretreatment with organic solvents before fusion. As in the method of d), the content of the binder is low because it uses a binder pitch as in the conventional carbon molding, but as in the method of b), there are disadvantages in that pores are formed by the volatile component of the binder.

In the method of e), there are no restrictions on the raw materials, but it must be pulverized to less than 1-5㎛, which requires a lot of cost for grinding power and high temperature and high pressure (2000 ℃, 2000㎏f / ㎠) during molding.

Accordingly, an object of the present invention is to provide a high-density and high-strength carbon molded article without the use of a binder in a state in which the shape and the optical structure of the raw material are not limited and the limitation of particle size is alleviated rather than the conventional method.

Hereinafter, the present invention will be described in detail.

The present invention relates to a method for producing a carbon molded product using pitch as a raw material, wherein the particles are pulverized into particles having a softening point of 300 ° C. or higher to a particle size of 250 μm or less without regard to optical structure, and then the particles are subjected to 200-350 ° C. The present invention relates to a method for producing a carbon molded product which is subjected to incompatibility treatment in an air atmosphere for 1-8 hours and molded at a pressure of 50-300 kgf / cm 2, followed by sintering of an inert atmosphere at a temperature of 900 ° C. or higher.

In addition, the present invention is a method for producing a carbon molded body using the pitch as a raw material, the concentration of 0.1-14N after grinding the pitch having a softening point of 300 ℃ or more to a particle size of less than 250㎛ without regard to the optical structure After impregnating into a nitric acid solution having a temperature of 40-60 ℃, stirred for 30-180 minutes to dissolve the particles and surface modification and washing and drying them, and then molded at a pressure of 50-300kgf / ㎠ After that, the present invention relates to a method for producing a carbon molded product which is sintered at an inert atmosphere at a temperature of 900 ° C. or higher.

In the above, as a starting material, a tar or pitch material is heat-treated to produce pitches having a softening point of 300 ° C. or higher, and the optical tissues of the pitches having high softening points may be partially anisotropic to partially anisotropic or full-faced. Anisotropy may be shown.

The raw material pitch was charged to a ball mill and then pulverized in air to a particle size of 250 μm or less, and it was heated for 1-8 hours in an air atmosphere at a temperature of 200-350 ° C. to impregnate the particles, or 0.1-14 N After soaking in nitric acid solution and heating for 30-180 minutes at a temperature of 40 ° C.-60 ° C., incompatibility and surface modification, washing and drying, then pressurized at room temperature or high temperature with 50-300 kgf / cm 2 pressure After molding, the product is sintered in an inert atmosphere of 900 ° C or higher.

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

The softening point of the material produced after the heat treatment of the pitch should be 300 ℃ or higher. If the softening point is lower than this temperature, low boiling point volatiles remain, and at least the minimum caking component necessary for bonding is present during the rise to the sintering temperature in the manufacture of the molded product. Due to the discharge of low boiling point volatiles, a large amount of pores may be present in the carbon moldings, and due to the gas pressure, it may not be able to maintain a constant shape and have a swollen form, and thus, it may not be possible to manufacture a required molded body.

Therefore, in order to maintain the minimum content of the binder component, the softening point must be 300 ° C. or more to be used as a raw material without pretreatment. The particle size limit of 250 μm is the same as the reason described above, when the particles become more than this, there may be pore formation in the particles due to the volatiles generated inside the particles, and in the case of post oxidation, i.e., treatment of air and liquid oxidants, A long time is required for diffusion to the inside, so that the overall process time may be long.

In addition, the use of the liquid oxidizing agent can be expected not only to bond only to the caking component but also to the surface modification action outside the particles as shown in FIG.

This is because the heating process can be shortened. In addition, the pressure of 50-300kgf / ㎠ is the optimum molding pressure according to the size of the particles. When the particles become fine, a layer is formed in the molded body due to the repulsion caused by the compression of the molded product, which causes a defect in the production of the final product. In the particle size of the present invention because it indicates that the above pressure is appropriate. The lower limit of the sintering temperature is because in the case of the present sample having little caking component, the remaining caking component must be sintered at a temperature of 90 ° C. or higher so that the particles can be mutually bonded.

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

Example 1

Ashland petroleum pitch A-240 (trade name) was heat treated to produce pitch with anisotropy and softening point of 330 ℃, and then pulverized below 100 mesh and oxidized at 300 ℃ for 1 hour in air atmosphere. By molding at room temperature, a molded article having a diameter of 25.5 mm and a height of 5 mm was prepared. It was heated at a rate of 2 ℃ / min under nitrogen atmosphere, maintained at 1000 ℃ for 30 minutes, cooled to 3 ℃ / min to produce carbide, and the apparent density and compressive strength were measured. The apparent density of this carbon molded product was 1.46 g. / Cm 3 and the compressive strength was 600 kg / cm 3, the appearance of which is shown in FIG.

Example 2

Heat-treated Korean coal tar pitch was prepared to produce an isotropic pitch with a softening point of 350 ℃, then pulverized it below 100 mesh, insoluble in nitric acid solution at 60 ℃, and then surface-modified and washed with distilled water. After the dried sample was press-molded at room temperature with a pressure of 250㎏f / ㎠ to form a molded body, and then heated to a temperature of 3 ℃ / min under nitrogen atmosphere to 950 ℃ and immediately cooled to a cooling rate of 3 ℃ / min Carbide was prepared.

The apparent density of the carbon molded body was 1.445 g / cm 3 and the compressive strength was 800 kgf / cm 2, the outer shape of the carbon molded body is shown in FIG. 2 (b), and the internal structure is shown in FIG. 3.

Example 3

The sample of Example 2 was pulverized to 60 mesh or less and then oxidized while stirring in nitric acid solution and press-molded at a pressure of 100 kgf / cm 2 to obtain the molded body at 900 ° C. at a temperature rising rate of 2 ° C./min under nitrogen atmosphere. After heating, it was maintained for 1 hour and cooled at a rate of 5 ° C./min to prepare a carbon molded body. The apparent density and the compressive strength were measured, and the apparent density was 1.48 g / cm 3 and the compressive strength was 500 kgf / cm 3. The external shape is shown in FIG. 2 (C).

Example 4

After heat treatment of Korean coal tar pitch, an anisotropic liquid crystal containing pitch having a softening point of 300 ° C. containing about 50% of anisotropic structure of spherical shape was pulverized to 120 mesh or less, and the pulverized sample was heated to about 50 ° C. in nitric acid solution. After washing and drying the surface oxidation and modification, the molded body formed at room temperature at a pressure of 200 kgf / cm 2 was sintered at 900 ° C. for 1 hour in an inert atmosphere at a temperature rising rate of 2 ° C./min, and cooled to prepare a carbon molded body. The compact had a density of 1.454 g / cm 3 and a compressive strength of 500 kgf / cm 2.

In summary, the results of Examples 1-4 show that the present invention is not limited to the optical properties of the raw materials using pitches. It can be seen that molded bodies can be produced and, as shown in FIGS. 2 and 3, maintain a good appearance and have a dense structure without the use of a binder.

As described above, the present invention can produce a carbon molded body having the same level of density in a state in which the limitation of the particle size is not limited to the shape and optical structure of the raw material and the limitation of the particle size is relaxed compared to the conventional method, and requires the use of a binder. Since it is not so that there is an effect that can produce a molded article having excellent characteristics at room temperature.

Claims (2)

In the method for producing a carbon molded product using pitch as a raw material, the pitch is pulverized to a particle size of 250 μm or less after a softening point of 300 ° C. or more without regard to optical structure, and then the particles are air atmosphere at 200-350 ° C. 1-8 hours insoluble treatment at 50-300 kgf / ㎠ and molded at a pressure of 900 to more than 900 ℃ sintered in an inert atmosphere, characterized in that the carbon molded product manufacturing method. In the method for producing a carbon molded product using pitch as a raw material, a pitch having a softening point of 300 ° C. or more is pulverized to a particle size of 250 μm or less without being bound to an optical structure, and then to a nitric acid solution having a concentration of 0.1-14 N. After immersion, it was heated to a temperature of 40-60 ° C., stirred for 30-180 minutes, insoluble in particles and surface modified, washed and dried, and then molded at a pressure of 50-300 kgf / cm 2 and then A method for producing a carbon molded article, which is sintered in an inert atmosphere at a temperature.

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