JP2003055057A - Method of manufacturing carbon fiber reinforced carbon material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a high quality carbon fiber reinforced carbon material (C/C) inexpensively and in a short time without necessitating repetition of an impregnation process for densification in the manufacturing method of the C/C. SOLUTION: The carbon fiber reinforced carbon material is manufactured by mixing carbon fiber chop having 2 to 30 mm length with a filler material prepared from one of or the combination of pitch, coke and carbon fine powder along with a resin and a solvent, drying and pulverizing the resultant dry mixture into <=10 mm, molding and firing at 10-50 deg.C/hr temperature rising rate in a temperature ranging from 400 deg.C to 600 deg.C under an inert atmosphere.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a carbon fiber reinforced carbon material, and more particularly to a carbon fiber chop, a filler material such as pitch, and a high performance carbon fiber reinforced carbon material using a resin at low cost in a short time. It relates to an obtainable manufacturing method.

[0002]

2. Description of the Related Art Conventionally, carbon fiber reinforced carbon materials (hereinafter referred to as C / C) are lightweight and have excellent high temperature strength, heat resistance and impact resistance. It is a suitable material for applications.

Further, since C / C can be highly purified and has high corrosion resistance to silicon-based gas,
It has also been used in furnace parts for pulling silicon single crystals.

Although C / C is a material having excellent properties as described above, its use is limited due to its drawbacks of being extremely expensive and having a long manufacturing period.

The main causes of such drawbacks are that expensive long fibers are used as the carbon fibers, and it is necessary to repeat the steps of impregnating pitch and resin for densification in the manufacturing process and firing the carbon fiber several times. It is considered that. Therefore, in order to inexpensively produce C / C, a method of using inexpensive short fibers instead of long fibers has been attempted.

For example, Japanese Unexamined Patent Publication (Kokai) No. 5-306167 is an invention relating to a method for producing a short fiber reinforced C / C composite, and a short fiber reinforced C / C composite precursor containing short fiber carbon fibers and crushed pitches is added. While calcining under pressure or restraint, it is heated to 400 to 1200 ° C. in an inert atmosphere and fired.
It is a method for producing a short fiber reinforced C / C composite, which comprises heating and pressurizing under conditions of high temperature and high pressure of 00 ° C. or higher and 50 kg / cm ² or higher. According to this method, a short fiber reinforced C / C composite having a high bulk density can be easily manufactured in a short time.

Further, JP-A-6-183835 is an invention relating to the production of a C / C composite in which short fibers are used as a reinforcing material. Short fibers of carbon fibers and a matrix material are dispersed in a dispersion medium to which a thickener is added. By stirring and mixing in the medium, and then molding the resulting dispersion mixture and then drying to remove the dispersion medium, the short fibers of carbon fibers containing the above-mentioned thickener and the matrix material were uniformly dispersed. A method for producing a preform body for a short fiber reinforced C / C composite, which comprises obtaining a preform body. According to this method, short fibers are uniformly dispersed, and a C / C composite having stable quality can be provided at low cost.

These techniques are also effective methods for stably producing C / C in a short period of time, but since the impregnation step for densification needs to be carried out, the above-mentioned problems are sufficiently solved. There are aspects that have not been resolved.

Therefore, a method for producing high-quality C / C more inexpensively in a short time is desired.

[0010]

In view of the above problems, the present inventor has
Provided is a method of producing C / C at low cost in a short time without repeating the impregnation step for densifying high quality C / C.

[0011]

In order to solve the above problems, the present inventor proposes that carbon fiber chops, which are short fibers, and a filler material such as resin or pitch are used under specific conditions. A method for producing C / C without repeating the conventional impregnation step. That is, a carbon fiber chop of 2 to 30 mm is mixed with a thermosetting resin, a solvent, a pitch, a coke, a carbon fine powder, or a filler material which is a combination thereof, and the mixture is dried to obtain a mixture. After crushing to 10 mm or less and molding, the temperature rising rate is 10 in the temperature range of 400 to 600 ° C. in an inert atmosphere.
It is a method for producing a carbon fiber reinforced carbon material, which is characterized by firing at -50 ° C / hr.

The present invention will be described in detail below.

In the present invention, a carbon fiber chop, a thermosetting resin and a filler material are used, but the following materials are used.

First, as the carbon fiber chop, pitch-based, PAN-based, or any other carbon fiber can be used, but a chopped carbon fiber having a length of 2 mm to 30 mm is used.

If the length of the fiber is less than 2 mm, the reinforcing effect is low, and the strength of the obtained C / C is lowered, and if it exceeds 30 mm, the dispersibility of the chop is poor and the C / C should be dispersed uniformly. Is difficult.

The amount of carbon fiber chops used is such that the volume of carbon fibers contained in the final product C / C is 10 to 40%.
It is preferable to adjust so that

When the capacity is less than 10%, the reinforcing effect is low and C
The strength of / C decreases, and if it exceeds 40%, the dispersibility of the fiber is poor, and it becomes difficult to disperse it uniformly in C / C.

Next, as the resin used in the present invention, an ordinary thermosetting resin such as phenol resin or furan resin is used. Further, as a solvent compatible with such a resin, low boiling point methanol, acetone or the like is preferably used.

As the filler material, petroleum or coal-based pitch, high softening point pitch, coke, carbon fine powder and the like obtained by heat treatment of these are used, and these are used alone or in combination. To do.

It is necessary that the composition of this filler has a softening point of 10% by weight or more.
If it is less than the above range, the obtained C / C characteristics are deteriorated.

The above carbon fiber chop, resin, solvent and filler are mixed and dried.

The ratio of filler material to resin is 1 / 0.5 to
It is preferably 1/1. When the ratio is less than 1 / 0.5, the strength of C / C decreases, and when it exceeds 1/1, the bulk specific gravity decreases, and dense C / C cannot be obtained, which is not preferable. A suitable drying temperature is 100 ° C. or lower, and if the drying temperature is 100 ° C. or higher, curing of the resin proceeds and cracks may occur during molding.

The mixture obtained by mixing the carbon fiber chop, the resin and the filler material as described above is crushed to 10 mm or less. When it exceeds 10 mm, the uniformity of C / C obtained is deteriorated, which is not preferable. Then 10mm as above
The crushed mixture is molded below, but the molding temperature is 15
Suitably, the pressure is 0 to 200 ° C. and the pressure is 10 to 100 kg / cm ² .

After molding, C / C is performed by firing in an inert atmosphere.
In the temperature range of 400 to 600 ° C., the heating rate is set to 10 to 50 ° C./hr during firing, and the temperature is raised at a gentle rate of about 1/3 of the other temperature ranges. 400-60
In the temperature range of 0 ° C., unless the temperature is raised slowly as described above, problems such as cracks tend to occur.

By the above method, high quality C / C can be manufactured without performing densification treatment such as impregnation.

[0026]

According to the present invention, with regard to the method for producing C / C, it is possible to obtain high quality C / C without repeating the impregnation step for densification as in the conventional method, and at low cost in a short time. C / C can be produced and is industrially useful.

[0027]

[Examples and Comparative Examples]

Example 1 A pitch-based carbon fiber chop cut into 10 mm was mixed with a filler material together with a resole-type phenol resin and methanol. For the filler material, 80% coke crushed to have a pitch of 20% by weight and an average particle size of 5 μm.
Contains by weight. The obtained mixture was dried at 80 ° C. and then pulverized to 8 mm or less. In the above mixture, the amount of carbon fiber chop added was 20% by volume in C / C.
% So that the ratio of filler to resin is 1 /
It was set to 0.75. Next, the pulverized mixture was charged into a mold and molded at 170 ° C. and a pressure of 50 kg / cm ² . Next, it was fired in a nitrogen gas atmosphere to obtain C / C. The firing rate in the temperature range of 400 to 600 ° C. was 20 ° C./hr on average during firing, and about 1% of the other temperature range. The speed was set to / 3. The obtained C / C had a bulk specific gravity of 1.55 and a bending strength of 15 kg / mm ² .

[0028]

Comparative Example 1 The volume ratio of carbon fiber in Example 1 was 5
C / C was obtained in the same manner as in Example 1 except that the percentage was changed to%. The obtained C / C had a bulk specific gravity of 1.58 and a bending strength of 5 kg / mm ² , and the strength was remarkably lowered.

[0029]

[Comparative Example 2] The length of the carbon fiber in Example 1 was set to 1 mm.
C / C was obtained in the same manner as in Example 1 except that The obtained C / C has a bulk specific gravity of 1.55 and a bending strength of 7 kg /
mm ² , which was lower in strength than that of Example 1.

[0030]

[Comparative Example 3] The length of the carbon fiber in Example 1 was 50 m.
C / C was obtained in the same manner as in Example 1 except that m was set. However, the carbon fibers were not well dispersed, and C / C in which the fibers were uniformly dispersed could not be obtained.

[0031]

Comparative Example 4 C / C was obtained in the same manner as in Example 1 except that the proportion of the pitch in the filler was 5% by weight. The obtained C / C bulk specific gravity is
1.50, the bending strength is 8 kg / mm ² , Example 1
The strength was reduced compared to.

[0032]

[Comparative Example 5] C in the same manner as in Example 1 except that the ratio of the filler to the resin in Example 1 was 1 / 0.3.
/ C was obtained. The obtained C / C had a bulk specific gravity of 1.48 and a bending strength of 5 kg / mm ² , which was lower than that of Example 1.

[0033]

[Comparative Example 6] The same treatment as in Example 1 was carried out except that the temperature rising rate in the temperature range of 400 to 600 ° C in Example 1 was set to 60 ° C / hr on average. However, cracking occurred during firing, and good C / C could not be obtained.

Claims (3)

[Claims] 1. A carbon fiber chop of 2 mm to 30 mm is obtained by mixing with a thermosetting resin, a solvent, a pitch, a coke, a carbon fine powder or a filler material in which these are combined, and drying. A carbon fiber reinforced carbon material, characterized by crushing the mixture to 10 mm or less and shaping it, and then firing it in an inert atmosphere at a temperature rising rate of 10 to 50 ° C./hr in a temperature range of 400 to 600 ° C. Manufacturing method. 2. The method for producing a carbon fiber-reinforced carbon material according to claim 1, wherein the carbon fiber content of the obtained carbon fiber-reinforced carbon material is 10 to 40%. 3. The method for producing a carbon fiber reinforced carbon material according to claim 1, wherein the proportion of the material component having a softening point in the filler material is 10% by weight or more.