JPH02124766A - Production of carbon fiber reinforced carbonaceous material - Google Patents

Abstract

PURPOSE:To increase density and strength by subjecting prepreg obtd. by impregnating or coating carbon fibers with a specified matrix binder to laminating and hot press molding, curing the binder and carbonizing the cured binder by calcining. CONSTITUTION:Carbon black having >=50nm particle size and <=100ml/100g DBP oil absorption is uniformly dispersed in an org. solvent such as acetone or ethanol by <=10wt.% under ultrasonic vibration, a precondensate of thermosetting resin such as liq. phenol resin is added by 100-400 pts.wt. per 100 pts.wt. org. solvent and they are mixed to obtain a liq. matrix binder. Carbon fibers are impregnated or coated with the binder and the binder is half cured. The resulting prepreg is subjected to laminating and hot press molding, the binder is cured by heating and the cured binder is carbonized by calcining in a nonoxidizing atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a carbon fiber reinforced carbon material (hereinafter referred to as rC/CC/C material) having high density.

[Prior art] C/C materials are usually made by impregnating or coating a carbon fiber woven fabric, felt, tow, etc. with a low-viscosity matrix binder represented by a thermosetting resin, and then laminating and hot-pressing the materials. after,
Manufactured by hardening and calcination carbonization processes. However, in this manufacturing method, the matrix binder is extruded to the outside during the prepreg formation or laminated hot press molding process.
There is a problem that it escapes or volatilizes during firing and carbonization, resulting in a decrease in mm density. Therefore, in order to impart sufficient density and strength for practical use, it is necessary to first repeat the process of forcibly impregnating the manufactured C/C material with carbonizable resin and carbonizing it, or to add pyrolytic carbon using the CVD method. It is necessary to perform secondary reinforcing treatment such as depositing, which makes the process complicated and increases manufacturing costs.

As a means for solving such problems, a method is known in which fine powder of carbonaceous or carbonizable material is mixed into a matrix binder to increase the density and improve the strength performance of the tu weave.

For example, in the invention of Japanese Patent Publication No. 60-52103 by the present applicant, the carbonaceous or carbonizable material is selected from carbon black with a particle size of 80 or less, carbon, graphite, or cured resins such as phenolic, furan, and dihinylbenzene. fine powder to matrix binder at a ratio of 10 to 6
This is a C/C material manufacturing technology characterized by addition and mixing in the range of 0 weight percent, and after that, sinterable carbon fine powder such as pitch raw coke is added to 7 trinox made of thermoplastic resin. Method of mixing with binding material (Japanese Patent Application Laid-Open No. 62-8336
9) have been proposed.

[Problems to be Solved by the Invention] In the above method, it is desirable to make the particle size of the powder of the carbonaceous or carbonizable substance mixed in the matrix binder as small as possible. However, there are limits to mechanically pulverizing solid carbon materials, graphite materials, etc., and in industrial pulverization, the average particle size is at most II! The limit is up to m. In this respect, carbon black is advantageous for application to this purpose because it is an ultrafine powder with a particle size (aggregate unit) of several +n+a at the production stage and does not need to be pulverized.

The present invention was developed by reexamining the matrix composition of carbon blank from this viewpoint and finding the optimal conditions for its use.

[Means for Solving the Problems] The method for manufacturing a C/C material according to the present invention involves laminating and hot-pressing a prepreg formed by impregnating or applying a matrix binder to carbon fibers, and then hardening and firing carbonization. In a method for producing a carbon fiber reinforced carbon material, a carbon blank is uniformly dispersed in an organic solvent in an amount of 10% or less, and then a thermosetting resin is mixed to form a liquid material, which is then mixed with a thermosetting resin. Its structural feature is that it is used as a sox binding material.

Carbon fiber, which serves as a reinforcing material, is used in the form of plain fiber, woven fabric such as twill weave, felt, or tow, depending on the purpose, and the thermosetting resin, which is the main component of the matrix binding material, is
A highly carbonizable liquid resin such as a phenol-based or furan-based resin is used.

There are no particular restrictions on the type, properties, etc. of the carbon black to be mixed into the thermosetting resin, but it is desirable to select carbon black that has as large a particle size as possible and as small a structure as possible. Suitable particle properties include a particle size of 50 nm or more;
DBP oil absorption is 1100ml/100g or less.

To mix carbon black with a thermosetting resin, first add carbon black to an organic solvent such as ethanol or acetone, apply vibrations such as ultrasonic waves to uniformly disperse it, and then perform initial condensation of the thermosetting resin. The method of adding things is adopted.

At this time, it is important to set the blending amount of carbon black to 10% by weight or less, preferably within the range of 5 to 10% by weight, based on the organic solvent. The tissue density of the wood decreases rapidly. In addition, the mixing amount of the thermosetting resin is 1 part by weight for 100 parts by weight of the solvent.
It is desirable to set it in the range of 00 to 400 parts by weight.

By using the above mixing order and blending ratio in combination, it is possible to form a liquid matrix binder in which carbon black is homogeneously dispersed in the thermosetting resin.

The carbon black-containing matrix binder thus formed is impregnated or applied onto carbon fibers and semi-cured to form a prepreg.

Next, prepregs are laminated and hot-press molded, and then the matrix binding material is heated and hardened, and then fired and carbonized in a non-oxidizing atmosphere to produce a C/C material.

Incidentally, it is also possible to repeat the process of impregnating or coating the manufactured C/C material with the carbon black-containing matrix binder and firing and carbonizing it, thereby further densifying the structure of the surface layer portion. be able to.

[For production]

In the above manufacturing process, the carbon black interposed in the matrix binder is easily filled and retained inside the carbon fiber mesh along with the thermosetting resin, and the resin component is squeezed out during the prepreg or lamination heat-pressing process. In addition, due to its ultra-fine particle characteristics, the resin component is
It acts effectively to reduce and compensate for voids caused by scattering.

Through these actions, tissue densification and strength improvement are brought about.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

Examples 1-2, Comparative Examples 1-2 Particle size 62n+a, DBP oil absorption amount 87iffi/
100 g of carbon black (manufactured by Tokai Carbon ■, 5east V) having particle properties was added to acetone in amounts of 0.5, 10 and 20% by weight, and uniformly dispersed using an ultrasonic device. Next, a phenol resin liquid (manufactured by Dainippon Ink Industries, Inc., P5900) was added thereto at a ratio of 230 parts by weight to 100 parts by weight of acetone, and the mixture was thoroughly mixed and suspended using an ultrasonic device.

A plain-woven carbon fiber cloth (highly elastic polyacrylonitrile type) was immersed into the matrix binding material thus formed for impregnation treatment. Prepreg obtained by semi-curing this (
14 M layers of FTi (150 fins horizontally, 0.38 mm thick) were placed in a mold, heating temperature 110'C1 applied pressure 2
Hot pressure molding was carried out under the condition of 0 kg/cd.

After the molded product was completely cured at 250°C, it was transferred to a firing furnace maintained in a nitrogen atmosphere and heated at a rate of 5°C/hr for 1 hour.
The temperature was raised to 000°C and the mixture was fired and carbonized for 5 hours.

The process of impregnating the obtained C/C material with a phenol resin liquid under vacuum pressure and re-firing at 1000°C (re-impregnation) in the same manner as above was repeated three times.

The C/C material manufactured in this way was
The degree of weight loss of each sample was measured by exposing it to a temperature of c for 30 minutes. The results are shown in Table 1.

Table 1 From the results in Table 1, it was found that Example 1.2 using the carbon blank-containing matrix binder of the present invention had a significantly higher tissue density and a significantly lower oxidation rate than the comparative example. It will be done.

[Effect of the invention] As described above, according to the present invention, high-density, high-strength C/C
Since the material can be manufactured at low cost, the effect on industrial production is extremely large.

Patent applicant: Tokai Carbon Co., Ltd.

Claims (1)

[Claims] 1. In a method of producing a carbon fiber reinforced carbon material by laminating and hot-pressing a prepreg formed by impregnating or applying a matrix binder to carbon fibers, and then curing and sintering carbonization, the blending amount of carbon black is 10% by weight or less. A method for producing a carbon fiber-reinforced carbon material, characterized in that a liquid material formed by uniformly dispersing carbon fiber in an organic solvent in advance and then mixing with a thermosetting resin is used as a matrix binder.