JPS5935841B2 - Tansozairiyounoseizohou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carbon material and a method for producing a high strength carbon fiber reinforced carbon material.

Conventionally, as a manufacturing method for carbon fiber-reinforced carbon materials, several sheets of graphitized cellulosic woven fabric are coated with furfural-ketone condensation products, phenol formaldehyde resin, etc. by spraying or coating, and the thus coated sheets are coated. A known method is to stack the laminate to form a laminate, heat the laminate under pressure to harden the binder, and then heat it in a non-oxidizing atmosphere to carbonize it. In this case, there is non-uniform expansion and contraction of the binder due to variations in the thickness of the binder, which tends to cause deformation and internal cracks.

Another method is to mold carbon or graphite fibers into a mold, infiltrate the molded product under pressure with a binder such as a phenolic condensation product, a urea condensation product, an epoxy resin, Dextroz, or coal tar pitch. The product is compressed to remove excess binder, then pressure-cured, and after curing is fired in a protective atmosphere, and the fired product undergoes the impregnation and firing process several times again depending on the density desired for the final product. It has been known.

According to this method, the density of the product is at least 1.4 f/
Obtaining the Ce version required more than six impregnation and firing cycles, which required a long manufacturing time.

In addition, a method of impregnating a molded product made of carbon or graphite fibers with a binder is used, but the wettability of the binder and the fibers is poor (particularly in the case of large molded products, penetration into the interior is incomplete, resulting in defects). There was a problem that it was easy to leave a residue.

The purpose of the present invention is to solve the above-mentioned conventional problems and to realize a method for manufacturing carbon materials that has good bonding between fibers and binders, is free from defects (and can shorten manufacturing time). be.

In order to achieve the above object, the gist of the present invention is to coat carbon fibers with an organic binder, mold the obtained fibers into a desired shape, and then heat the molded product while applying pressure. The present invention resides in a method for producing a carbon material, characterized by carbonizing it and further graphitizing it as necessary.

The carbon fibers mentioned above are regenerated cellulose, polyacrylonitrile, vinylon, lignin poval, pitch-based (e.g., polyvinyl chloride pitch, petroleum asphalt, crude oil cracked pitch, petroleum sludge, tetrabenzophenazine pitch, coal tar pitch, etc.), heat-resistant organic polymers (e.g., polyamide, polyimide, polyhenzimidazole, polybenzoosazinone, polyquinazolinedione, polyoxydiazole, polybenzoxadione, polyoxydiazole, polybenzothiazole, etc.), phenolic resin, chloride Copolymers of vinylidene and polyvinyl chloride, furan-based resins, and other organic polymers are used as raw material fibers for production, and if necessary, they are treated to make them infusible, and then the carbonization temperature ( That is 80
0 to 3,000°C) or higher, including all those obtained by heat treatment at a temperature of 8oO to 1,500°C, which are referred to as carbonaceous fibers, and those whose heat treatment temperature is 2,000°C or higher are called graphite fibers. .

Further, carbon fibers can be used in any form such as cloth, tape, thread, felt, braided product, chopped, paper, etc.

As the organic binder described in the present invention, the above-mentioned organic polymer substances used for spinning raw material fibers for producing carbon fibers are appropriately selected and used alone or in combination.

Among organic polymeric substances, it is preferable that pitch-based and polyacrylonitrile-based substances in particular be carbonized at 200 to 500° C. to distill off low-molecular components and increase the carbon content prior to coating.

If necessary, an organic solvent is added to the organic binder to improve wetting with the carbon fibers, the viscosity is adjusted appropriately, and the carbon fibers are coated by dipping or impregnation.

The soaked or impregnated fibers are then washed or dried to remove or volatilize the organic solvent, thereby obtaining carbon fibers uniformly coated with the organic binder.

The coated carbon fiber is molded by a lamination method, a filament winding method, or the like.

The molding can be made more compact if it is heated if necessary, and the gas is thoroughly degassed while pressurizing or depressurizing.

Molded products using pitch-based or polyacrylonitrile-based organic binders can be used as is or with potassium permanganate,
After soaking in a solution containing an oxidizing agent such as potassium dichromate,
This is heated in an oxidizing atmosphere such as air, oxygen, ozone, nitrogen oxide, nitric acid gas, sulfur oxide, halogen, etc.
It is preferable to perform the infusibility treatment by heating to ℃.

The untreated or infusible molded product is directly pressed in a mold, or it is heated externally or directly heated while being pressurized by using powder as a pressure medium, or by inert gas pressure such as nitrogen or argon. , 300-5 by induction heating etc.
00°C, then fired to 800-1500°C, carbonized to form a carbon fiber-carbon binder carbon material, and further heated to 2400-3000°C as necessary to form a graphite fiber-graphite bond. A carbon material consisting of a carbonaceous agent is obtained.

When an organic polymer substance of the same type as the raw material fiber for manufacturing carbon fiber is used as an organic binder (for example, pitch-based carbon fiber-pitch-based binder, polyacrylonitrile-based carbon fiber-polyacrylonitrile-based binder), the organic binder This is particularly effective because the carbon binder obtained by carbonization and the carbon fibers exhibit almost the same properties.

The difference in the coefficient of thermal expansion between the two is very small, and the thermal stress generated during heat treatment and cooling after treatment is also small, so the occurrence of peeling, cracks, deformation, etc. during this time can be greatly reduced. became possible.

The fired body obtained by the above method can of course be re-impregnated and re-fired in order to achieve higher density, higher strength, and impermeability, but since the strength of the primary fired body is higher than that of the conventional method, , it was sufficient to do it about 1 to 2 times, instead of 6 times as in the conventional case.

The present invention will be explained in detail below with reference to Examples.

Example 1 Reinforced fiber material with a diameter of 5 μm and a tensile strength of 320 kg/m
4. A coated fiber was made using polyacrylonitrile carbon fiber with an elastic modulus of 21 t/ma as a polyacrylonitrile organic binder.

DMSO (dimethyl sulfoxide) was used as a solvent for polyacrylonitrile, and the amount thereof was 95 parts of dimethyl sulfoxide per 5 parts of polyacrylonitrile.

After the coated fibers are wound around a mandrel, they are washed with water to remove the solvent, rolled, and then placed in a hot air drying oven at 150°C.
Heated at ℃ for 1 hour.

After drying, the coated fibers were cut, laminated in one direction, and molded into a dragon shape of 50Wx200Lx5 using a mold.

The molding is preheated at 220℃ for 10 minutes and the molding is performed at 20ky/ca.
The test was carried out under pressure of r.

The fiber content of the molded body was 60% by volume.

This molded body was heated in air at 250° C. for 6 hours to perform infusibility treatment.

After the infusibility treatment, while applying a pressure of 50 kg/cnt in a mold sintering furnace, the heating rate was 250 to 90°C at a temperature increase rate of 100°C/Hr.
It was heated to 0°C to obtain a carbon material consisting of carbon fiber-carbon binder.

The properties of the obtained carbon material are shown below.

Specific gravity: 1.40 Bending strength: 37kg/ra Modulus of elasticity
...12 t/ma interlaminar shear strength...
... 3.Okg/rna Example 2 The carbon material obtained in Example 1 was immersed in coal tar pitch with a softening point of 80°C under a reduced pressure of 150°C11~1o7rL11LHg, and then under a pressure of 10kg/cn't. 1
Impregnated for hours.

The gold products were held at 200'C in chlorine gas for 2 hours and then fired to 900'C in a nitrogen atmosphere.

This impregnation and re-firing cycle was repeated twice to obtain a carbon material.

Its characteristic values are shown below: #'''C-, b9''・
) Specific gravity: 1.45 Bending strength: 42 kg/mi Elastic modulus -12,5t/m4 Interlaminar shear strength: 3.5 kg/ma Example
3 The carbon material obtained in Example 2 was graphitized by heating at 2400°C to obtain a carbon material of a graphite fiber-graphite binder.

Its characteristics are shown below. Specific gravity 1.
47

Claims (1)

[Claims] 1 Carbon fibers are coated with an organic polymer substance of the same type as the raw material fiber for manufacturing the carbon fibers as a binder, the obtained fibers are molded into a desired shape, and the molded body is heated under pressure to form carbon fibers. 1. A method for producing a carbon material, which is characterized by graphitizing the carbon material and, if necessary, graphitizing the material.