JPS62138361A - Manufacture of high density formed body from carbon material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for manufacturing a high-density molded body made of a carbon material.

[Background of the invention] Carbon materials (excluding diamond) are divided into amorphous carbon and graphite, and each of these comes in many forms such as molded bodies and m-fibers, and has excellent heat resistance and resistance to chemicals. Due to its stability and unique electrical properties, its field of application has expanded in recent years, from aerospace materials such as rocket nozzles to artificial heart valves.

Conventional molded bodies made of carbon materials are made using coke as an aggregate, mixed with tar or pitch as a binder, tempered, molded and fired, and further heated to 2500 to 3000°C if graphitization is required. It has been manufactured through a process of graphitization at high temperatures. However, recently there has been a strong trend toward fine carbon materials, and the chemical composition is clear and scientific research and development is more reliable than those based on petroleum or coal as raw materials. Raw materials, namely resins, are being used.

Graffy carbon material is a typical example of carbon materials made from synthetic raw materials. By using furan resin and phenolic fat as raw materials for Graffy Carbon material, new functions such as high strength and no gas permeability have been realized.

The new functions of glassy carbon material were realized by the raw materials and firing method. In other words, when the raw material thermosetting resin is slowly heated and fired, the carbon-to-carbon bonds that form the backbone of the molecular structure do not break down too much, and only the functional groups and hydrogen are released from the carbon backbone. As a result, a graphy carbon material is produced. However, since glassy carbon materials are formed through the process described above, when producing large products or thick plate materials, the molded product may be damaged by the resin groups and hydrogen gas generated during firing. There is a problem in that a region of high pressure is generated inside the molded body, which causes damage to the molded body. Therefore, the glassy carbon material has the disadvantage that it can only be produced industrially as a thin plate with a thickness of about 2 m+s or less.

[Object of the Invention] An object of the present invention is to provide a method for producing a high-density molded body made of a carbon material that can produce a large-sized or thick-walled high-density carbon material.

[Summary of the Invention] The above object is to heat a raw material containing a thermosetting resin as a main component to pressure mold a molded product through which an inert gas cannot pass, and then to mold the molded product into a molded product with a weight of 70 kg/cm2 or more. Under an inert gas atmosphere of pressure 4
This is achieved by a method for manufacturing a high-density molded body made of a carbon material, which is characterized by firing at a temperature of 00°C or higher.

As the type of resin, for example, phenol resin, furan resin, epoxy resin, etc. can be used. In addition, when a phenol resin is used, the effect of achieving high density is large.

Note that the raw material may contain, for example, carbon fiber, graphite powder, mesophase pitch, and the like.

In addition, when carbon fiber is mixed into the raw material, depending on the type of carbon fiber, fine bores may be formed along the carbon fiber during the polycondensation and carbonization process of the resin, and methane, hydrogen, etc. generated internally may be generated. This creates a path for the dissipation of water, which has the effect of reducing the occurrence of blisters in the molded product. In addition, by mixing carbon fibers that have a high affinity with resin after carbonization and carbon fibers that have been surface-treated with phenolic resin,
It is also possible to further increase the strength of the product after firing.

In addition, when carbon fiber is contained, the proportion in the total weight of the molded product is preferably 5 to 50 wt%, and the maximum is 50 wt%.
The reason why t% is used is because when 50wt% or more of carbon fiber is mixed, even if the molding pressure is increased to about 2000kg/cm, the molded product will not pass through inert gas such as argon or nitrogen. Furthermore, the reason why the minimum value is set at 5 wt% is because the effect of mixing carbon fibers into the raw material is the minimum value that appears in the method for producing high-density carbon materials.

The reason why the molded product obtained by heating raw materials under pressure is made into a molded product that does not allow inert gases such as argon or nitrogen to pass through is because the molded product does not allow inert gases such as argon or nitrogen to pass through. This is because when the molded body is porous, even if the molded body is fired under high pressure, the high-pressure gas also enters the pores, so the gas pressure does not act as a compressive force to promote densification.

In addition, in order to make a molded product that does not allow inert gas to pass through, a hot plate press or a warm isostatic pressure device is used, and the pressure is, for example, 10 to 3000 kg/cm', and the temperature is 1.
What is necessary is just to carry out at 50-400 degreeC.

The reason why the compact is fired at a temperature of 400° C. or higher in an atmosphere of an inert gas such as argon or nitrogen at a pressure of 70 kg/crn' or higher is as follows. That is, when the molded body is exposed to a high-pressure argon or nitrogen atmosphere, the molded body is compressed by the pressure of the gas. If the temperature is raised in this state, the resin undergoes polycondensation, and even if the functional groups try to detach from the carbon skeleton, gasification is suppressed by the pressure outside the molded body. decomposes into smaller molecules such as methane and hydrogen. Therefore, only hydrogen dissipates through minute pores that do not allow argon or nitrogen molecules to pass through. Therefore, the carbonization reaction progresses with a high residual amount of carbon (carbon yield) in the carbonizable substance, and a high-density carbon material is produced. This is because it becomes more noticeable when fired at a temperature of 400°C or higher.

Note that firing at temperatures below 400°C does not necessarily need to be carried out under high pressure; therefore, using a molded product that has been heat-treated to about 400°C under normal pressure, the temperature can be raised rapidly to about 400°C under high pressure. , the subsequent temperature increase rate is 200℃/hr
The cycle time can be shortened by firing at a lower temperature.

[Example] (Example 1) PAN-based carbon fibers were cut to a length of 0.13 mm from 100 parts by weight of novolac-based phenolic resin powder! a
80 parts by weight were mixed, and a liquid obtained by mixing 10 parts by weight of resol-based phenolic resin with 10 times the amount of methanol was mixed, dried, and then heated at 150°C in a mold press for 200°C.
The surface of the molded product obtained by pressure molding at a pressure of 1 kg/cm" has a luster and has a luster. When the density was measured by the Archimedes method, the density was found to be low as it was without water absorption. It can be measured and its density is 1.32g/
It was cm3. This molded body was fired at 400° C. under normal pressure to obtain a sample with a density of 1.30 g/cm 3 . This sample was placed in the HIP device, and after evacuation and gas replacement with argon gas, heating power was applied to the heater of the HIP device at the zero order filled with approximately 300 kg/cm'' of argon gas. 120 at a heating rate of 200'O/h.
The temperature was raised to 0°C. At the same time, argon gas was supplied, and the sample was finally held at 1200° C. and 1000 kg/c for 2 hours, then the temperature was lowered and the pressure was reduced, and the sample was taken out. The sample is approximately 3 thick
．． It was carbonized at 2+am without causing any large blisters. The density determined by the Archimedes method was 1.84 g/c+m3.

(Comparative Example 1) A molded body prepared in the same manner as in Example 1 was fired at 1200° C. under normal pressure and in an argon gas atmosphere. The temperature increase rate is 400℃/h up to 400℃, and 20℃ at higher temperatures.
/h. The sample after firing had a large bulge in the center. After removing this bulge, the density was measured by Archimedes' method and found to be approximately 1.50 g/cm 3 .

(Example 2) Samples prepared in the same manner as in Example 1 (density 1, 30
g/crn') was placed in a HIP device, and after vacuuming and gas replacement with argon gas, approximately 70k
Heating power was then applied to the heater of the HIP stirrup, which was filled with argon gas at a temperature of hr and heated to 900°C. 9
The pressure after holding at 00℃ for 2 hours is approximately 200k.
g/crn'te was there. After lowering the temperature and pressure, the sample taken out was carbonized without causing any large blisters and had a density of 58 g/crn. 1, 30
g/crn') in HIP equipment 4, and vacuum
After gas replacement with argon gas, approximately 70 k
Filled with argon gas at g/c rn'. Next, heating power was applied to the heater of the HIP device, and the temperature was 600 ”
Heating to 400 °C at a temperature increase rate of C/hr, at the same time replenishing argon gas, and finally heating to 400 °C, zoo
kg/crn' for 3 hours. The density of the sample taken out after cooling and reducing the pressure was 1.35 g/C, and a slight increase in density was observed. However, since carbonization had hardly progressed, carbonization was attempted by heating this sample to 900°C at a temperature increase rate of 100°C/hr in an inert gas atmosphere under normal pressure. The sample after treatment had many large and small bulges and cracks. The density measurement results are approximately 1.35~
It was 1.40 g.

(Examples 3-6, Comparative Examples 3-6) Examples 3 to 6 and Comparative Examples 3 to 6 are shown in the table.

In the table, conditions not shown are the same as in Example 1.

As shown in Examples 1 to 6, products to which the present invention is applied can obtain products with higher density when fired in a high-pressure argon or nitrogen atmosphere compared to products fired under normal pressure. However, if heating and pressure molding is not performed during molding.

Even when fired in a high-pressure gas atmosphere, only a porous product can be obtained, and a high-density product cannot necessarily be obtained.

(Effects of the present invention) The present invention makes it possible to manufacture thick-walled or large-sized, high-density carbon products, and it is thought that the uses of carbon materials will further expand, making a significant contribution to industry.

Claims (5)

[Claims] (1) Heat a raw material whose main component is a thermosetting resin and press-form it into a molded body through which argon or nitrogen gas cannot pass,
A method for producing a high-density molded body made of a carbon material, characterized in that the molded body is then fired at a temperature of 400° C. or higher in an argon or nitrogen gas atmosphere at a pressure of 70 kg/cm^2 or higher. (2) A method for producing a high-density molded body made of a carbon material according to claim 1, wherein the raw material contains carbon fiber. (3) The proportion of carbon fiber in the total weight of the molded body is 5 to 5
A method for producing a high-density molded body made of the carbon material according to claim 2, wherein the content is 0% by weight. (4) A method for producing a high-density molded body made of a carbon material according to any one of claims 1 to 3, wherein the thermosetting resin is a phenol resin. (5) A high-density molded body made of the carbon material according to any one of claims 1 to 4, wherein the molded body before firing is heated to a temperature of 400°C or less under normal pressure, and then fired. manufacturing method.