JPH0694363B2 - Glassy carbon molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] Glassy carbon has been applied to packing, crucible chemical plants, gaskets and the like because it has impermeability, chemical stability, etc. It is also attracting attention as a material for fuel cell separators. The present invention relates to a molded article made of such glassy carbon.

[Conventional technology and its problems]

Glassy carbon obtained by firing an organic polymer such as furan resin in an inert atmosphere is a material excellent in heat resistance, strength, corrosion resistance, gas exhaust adsorption and liquid impermeability. As described above, it has been applied to various molded products (Japanese Patent Laid-Open No. 59-21512).

In order to further increase the strength of the glassy carbon, asbestos, coal wool, inorganic fibers such as carbon fibers are blended into the glassy carbon, or organic fibers such as cellulose fibers are blended and then fired. An inorganic method has been tried (Japanese Patent Laid-Open No. 61-83611). Although the strength of the glass-like carbon molded product is certainly improved by the blending of such fibers, the adhesion between the fibers and the glass-like carbon is a problem, and due to poor adhesion, the chips are missing at their interfaces. However, there are drawbacks such as cracking or peeling, lowering of strength, and deterioration of non-passability of glass.

The object of the present invention is to provide a glassy carbon molded article which does not have the above-mentioned drawbacks.

[Means for solving problems]

As a result of various studies to achieve the above-mentioned objects, the present inventors have found that when a carbide obtained by carbonizing an organic polymer for producing glassy carbon is used as an aggregate, the glassy carbon and the aggregate are used. Since and are derived from the same substance, they are considered to have an affinity for each other, and the idea that the problem of poor adhesion as described above will not occur is obtained. The present invention is based on the above idea.

That is, the present invention is a glassy carbon molded article obtained by firing a mixture of a heat dispersion product of a vinyl chloride resin and an aggregate made of a carbide of a thermal decomposition product of the vinyl chloride resin, A glassy carbon molded product in which the decomposition product is a mixture of the baked glassy carbon and the baked aggregate.

Hereinafter, the present invention will be described in more detail. The organic polymer used in the present invention is a vinyl chloride resin. Because vinyl chloride resin has less metal impurities than other organic polymers such as polyvinyl alcohol, oil-soluble phenol resin, alkylphenol resin, chlorinated paraffin, chlorinated polypropylene, vinyl acetate resin, polycarbonate, etc. The glassy carbon molded article thus obtained is also excellent in the above-mentioned adhesiveness, which is advantageous particularly when the application is a member for semiconductor production.

The thermal decomposition of the vinyl chloride resin is performed by heating the granular product or powder in an inert atmosphere, for example, in argon gas at 200 to 500 ° C. for 30 minutes or more. The desirable temperature and time for this is that the weight ratio (C / H) of carbon and hydrogen atoms in the thermal decomposition product is 10
It is a condition such that it becomes ~ 25, and it is better to set it in advance by experiments. The thermal decomposition product thus obtained is a pitch-like substance (hereinafter referred to as PC substance) and is a solid at room temperature.

The aggregate is a carbide of the vinyl chloride resin used as the raw material of the PC substance. Here, the carbide is not limited to the one that is completely carbonized, but rather, one in which a part of hydrogen atoms remains is preferable from the viewpoint of the above-mentioned adhesion.

The method of thermal decomposition for obtaining the aggregate may be the same as the method for obtaining the PC substance, but the heating temperature is 600 ° C. or higher, preferably 8
It is from 00 to 1000 ° C. The heating time may be 1 to 2 hours.

The particle size of the solid thus obtained is adjusted by a method such as crushing. The shape may be spherical or amorphous with a diameter of 50 μm or less, and may be rod-like or fibrous with a major axis of 500 μm or less. The optimum amount of aggregate for PC substance varies depending on the particle size and shape of aggregate, but if it exceeds 5 times the weight of PC substance (weight ratio), it becomes impervious and difficult to form uniformly. There is a problem in that The mixing method of the PC substance and the aggregate is to mix both powders at room temperature or knead them with a heating roll. Molding can be performed by using a roll to form a plate or a film, or using an extruder to form a cup or the like. The viscosity may be reduced by adding an organic solvent to the PC material during compounding and molding. Also,
It is also possible to add a solvent to form a slurry and obtain a plate-shaped molded body by the doctor blade method. Further, the slurry can be cast on a heat resistant material. From the viewpoint of solubility, the solvent is preferably an aliphatic chlorine thread solvent.

In the case of molding using a solvent, it is preferable to dry at a relatively low temperature (50 to 100 ° C.) before firing as described below.

The glass, carbon molded product is obtained by placing the molded product such as the film, plate or cup thus obtained in a firing furnace and heating it in an inert atmosphere. Heating conditions are from room temperature
5 ° C / min up to 30 ° C, 1 ° C / min from 300 ° C to 550 ° C,
It is desirable to raise the temperature from 550 ° C. to the final heating temperature at a heating rate of 10 ° C./minute, hold at the final heating temperature for 2 to 3 hours, and then cool to room temperature. The heating rate is related to the thickness of the molded product to be manufactured, and it is necessary to reduce the heating rate as the thickness increases. A final heating rate of 1000 to 1200 ° C is suitable. In addition, if it is necessary to perform the nonoxidizing treatment, it may be heated for several hours at a temperature of 150 to 350 ° C. in an air atmosphere in a firing furnace before the heating in the inert atmosphere.

Hereinafter, the present invention will be specifically described with reference to examples.

〔Example〕

Example: As an organic polymer, a vinyl chloride resin “SS-110S” manufactured by Denki Kagaku Kogyo Co., Ltd. was prepared. Put the resin in a quartz boat and pyrolyze for 90 minutes at 390 ° C in a nitrogen gas atmosphere to PC.
The substance was obtained. The PC material was crushed by a ball mill to obtain a powder having an average particle size of 2 μm. The C / H ratio (weight ratio) of the obtained PC substance was measured with a CHN coder (Yanagimoto MT-3).
It was 2.5.

At some time, a portion of the PC material was placed in a nitrogen gas atmosphere at 800 ° C.
The aggregate was made by firing for 2 hours for carbonization and then pulverizing with a ball mill to obtain a powder having an average particle size of 2.2 μm. 300 g of the powder of the PC substance and 1000 g of the aggregate are mixed, and the mixture is heated and kneaded with a calender roll at a roll temperature of 200 ° C.
A 5.3 mm thin plate was created.

Put the obtained thin plate in a baking furnace, and first, in an air atmosphere,
The mixture was heated at a temperature of 0 ° C. for 5 hours and then at 250 ° C. for 20 hours, and then the atmosphere was replaced with argon gas to start heating. The heating rate is 5 ℃ / min up to 300 ℃, 300-550 ℃
The temperature was set to 1 ° C / min during the period, and 10 ° C / min during the temperature range of 550 to 1200 ° C. When the temperature reaches 1200 ℃, stop the temperature rise for 3 hours 12
After keeping the temperature of 00 ° C, it was left to cool.

Five test pieces were prepared from the obtained glassy carbon thin plate having a thickness of 5 mm, and the Vickers hardness, the air permeability, the bending strength and the elastic modulus were measured, and the SEM observation was performed. These results were satisfactory as shown in the table. In addition, these measuring methods are as follows.

a) Vitzkers hardness ... Akashi Seisakusho MVK type equipment was used.

b) Ventilation rate ... After making the vacuum degree of 10 ^-7 torr or less on both sides of the chamber divided by the test piece, helium gas of 1 atm is flown to one side and the pressure rise on the other side is measured Done.

c) Bending strength: Measured according to JIS R7202.

d) Elastic modulus: Measured according to JIS 7202.

Comparative Example Graphite T-6P manufactured by Ibiden Co., Ltd. (density 1.90 as an aggregate)
g / cm ³ ) was crushed with a ball mill to an average particle size of 2.2 μm, and 5 test pieces were prepared under the same conditions and conditions as in the example. , Bending strength and elastic modulus are measured, S
EM observation was performed. The results are shown in the table.

First, the Vickers strength is lower than that of the examples, and the variation in the value is large. Second, the gas impermeability is poor.
Furthermore, the bending strength and elastic modulus are small. It is considered that these defects are due to poor adhesion between the aggregate and glassy carbon.

[Effects of the Invention] The glassy carbon molded article of the present invention uses the carbide obtained by carbonizing a vinyl chloride resin for producing glassy carbon as an aggregate to improve the adhesion between the aggregate and the glassy carbon. As a result, the hardness of each part of the molded product is stably increased,
Bending strength and elastic modulus are also increased. In addition, gas impermeability is improved.

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-54-41913 (JP, A) JP-A-54-26292 (JP, A)

Claims (1)

[Claims] 1. A glassy carbon molded article obtained by firing a mixture of a thermal decomposition product of a vinyl chloride resin and an aggregate made of a carbide of the thermal decomposition product of a vinyl chloride resin, wherein the thermal decomposition is performed. A glassy carbon molded product in which the product is calcined glassy carbon and the calcined aggregate is integrated.