JPH0648832A - Carbon-carbon composite molded body - Google Patents

Abstract

PURPOSE:To easily attain a high rate of residual carbon and high strength at a low cost by impregnating a specified compsn. into carbon fibers, molding the fibers under heating, and firing the resulting molded body in a nonoxidizing atmosphere. CONSTITUTION:Phenols such as phenol is mixed with aldehydes such as formaldehyde in 1:(1.0-2.0) molar ratio and they are brought into a reaction to obtain resol type phenolic resin having 150-300 number average mol.wt. Arom. aldehyde such as benzaldehyde and/or arom. alcohol such as saligenin is added to the phenolic resin by >=3wt.% and mixed to obtain a resol type phenolic resin compsn. for a carbon-carbon composite. This compsn. is impregnated into carbon fibers or carbon cloth, the fibers or cloth is molded under heating by compression molding or other method and the resulting molded body is fired at about 2,000 deg.C for <=5hr in a nonoxidizing atmosphere. Thus, the objective carbon- carbon composite molded body is produced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a phenol resin composition having a low viscosity and a high residual carbon ratio, which is suitable for carbon-carbon composite molding and a carbon-carbon composite using the phenol resin obtained in the present invention. It relates to a molded product. By using the resin of the present invention, it is possible to obtain an equivalent one that has conventionally required a multi-stage impregnation step by the single-stage impregnation, and it is possible to achieve great labor saving.

[0002]

2. Description of the Related Art Phenolic resins have hitherto been used as raw materials for carbonaceous materials and used for producing carbon-carbon composites. However, production of a carbon-carbon composite having sufficient strength requires multistage impregnation in which the steps of impregnation, drying, and firing are repeated several times, which requires a great deal of cost and labor, making it expensive. This is the current situation.

[0003]

The present invention relates to a phenol resin composition having a high residual carbon rate suitable for producing a carbon-carbon composite and a carbon-carbon composite molded product obtained by using the phenol resin composition. Since the present invention has required several steps of impregnation, drying, and firing until now, the production of a carbon-carbon composite, which was very expensive, is simplified, and a resin with a high residual carbon rate that can produce a molded product at low cost is provided. To provide.

[0004]

The present invention relates to a phenol resin composition having a high residual carbon rate suitable for producing a carbon-carbon composite, and a carbon-carbon composite molded product obtained by using the phenol resin composition. Phenolic resin composition used in the present invention, a specific resol type phenolic resin obtained by reacting phenols and aldehydes,
It comprises an aromatic aldehyde and / or an aromatic alcohol. As phenols, phenol,
Cresol, resorcinol, bisphenol A or the like can be used, but any phenol compound that is generally used when synthesizing a phenol resin can be used without particular limitation. May be.

As the aldehydes, formaldehyde, acetaldehyde and the like can be used, but there is no particular limitation, and any compound containing an aldehyde group can be used, and a mixture of several kinds may be used. . The ratio (molar ratio) of aldehydes to phenols is 1.
0-2.0 is suitable, but 1.2-1.5 is the best. The reaction time is not particularly limited and may be appropriately changed depending on the intended use and the required resin characteristics. However, by adjusting the number average molecular weight to about 150-300, workability and impregnation are improved. The property is greatly improved.
The catalyst used in synthesizing the phenol resin is not particularly limited, but bases can be used and can be appropriately selected and reacted depending on the required characteristics of the resin.

The aromatic aldehyde and the aromatic alcohol must be contained in the resol-type phenol resin in an amount of 3% by weight or more, and they may be used alone or in a mixture.
When the addition amount is less than 3% by weight, the viscosity cannot be sufficiently lowered, and it is necessary to lower the non-volatile content in order to lower the viscosity, which lowers the residual coal rate, and in the first stage impregnation, carbon-
Since there are many cavities inside the carbon composite, which causes a decrease in strength, multi-stage impregnation is required. As the aromatic aldehydes, benzaldehyde, hydroxybenzaldehyde and the like can be used and are not particularly limited. As the aromatic alcohol, benzyl alcohol, saligenin, phenethyl alcohol and the like can be used, but the aromatic alcohol is not particularly limited and may be used in combination. The carbon fiber used in the present invention is not particularly limited, but PAN type and pitch type are representative. Further, as the form of the fiber, carbon cloth such as thread (roving or yarn), plain weave, satin weave, etc. is used.

Although the molding method is not particularly limited, a pultrusion molding method, a filament winding method, a compression molding method,
A typical example is an autoclave molding method. Degassing is desirable for good molding. The firing method is not particularly limited in firing time and temperature as long as it is in a non-oxidizing atmosphere, but it is desirable to finally perform firing at 2000 ° C. for 5 hours or more in order to obtain a good carbon material. As described above, a resin having a high residual carbon rate and good workability needs to have a high non-volatile content and a low viscosity (high impregnating property). Blending of alcohol is very effective in achieving high non-volatile content and low viscosity, and further, after molding, firing in a non-oxidizing atmosphere gives a carbon-carbon composite with improved strength.

[0008]

EXAMPLES The present invention will be described below with reference to examples. "Parts" and "%" in the following all mean "parts by weight" and "% by weight". Further, the present invention is not limited to the embodiments. << Production Example 1 >> 1000 g of phenol and 1000 g of 37% formalin were placed in a reaction flask equipped with a stirrer, and 10% was added.
35 g of an aqueous sodium hydroxide solution and 35 g of a 10% aqueous potassium hydroxide solution were added, the mixture was reacted at 85 ° C. for 3 hours, dehydrated under vacuum, and 100 g of benzaldehyde was added and mixed to obtain a desired resol-type phenol resin solution. The obtained resin had a viscosity of 1.0 Pa · s and a nonvolatile content of 75%. The residual carbon rate of the resin is shown in Table 1.

<Production Example 2> Phenol 1000 g, 37
% Formalin 1000 g was placed in a reaction flask equipped with a stirrer, and added with 10% sodium hydroxide aqueous solution 35 g and 10% potassium hydroxide aqueous solution 35 g, reacted at 85 ° C. for 3 hours and then dehydrated under vacuum to give hydroxybenzaldehyde 1
The target resol type phenolic resin solution was obtained by adding and mixing 00 g. The viscosity of the obtained resin is 2.0 Pa · s,
The nonvolatile content was 76%. The residual carbon rate of the resin is shown in Table 1.

<Production Example 3> Phenol 1000 g, 37
% Formalin 1200 g was placed in a reaction flask equipped with a stirrer, 10% sodium hydroxide aqueous solution 35 g and 10% potassium hydroxide aqueous solution 35 g were added, reacted at 85 ° C. for 3 hours, dehydrated under vacuum, and added with benzaldehyde 200 g. The desired resol type phenol resin solution was obtained. The obtained resin had a viscosity of 2.1 Pa · s and a nonvolatile content of 75%. The residual carbon rate of the resin is shown in Table 1.

Comparative Example 1 Phenol 1000 g, 37
% Formalin 1000 g is placed in a reaction flask equipped with a stirrer, 10% sodium hydroxide aqueous solution 35 g and 10% potassium hydroxide aqueous solution 35 g are added, reacted at 85 ° C. for 3 hours, dehydrated under vacuum, and ethanol 100 g is added and mixed. The desired resol type phenol resin solution was obtained.
The resin obtained has a viscosity of 0.5 Pa · s and a nonvolatile content of 74%.
Met. The residual carbon rate of the resin is shown in Table 1.

Example 1 The resin solutions of Production Example 1-3 and Comparative Example 1 were heated to 70 ° C. to impregnate carbon cloth. Then, it was dried at 130 ° C. for 3 minutes to be B-staged to obtain a carbon prepreg. Eight prepregs obtained were laminated and press-molded at 130 ° C. and 60 kg / cm ² for 1 hour. The formed laminated plate was gradually heated in a non-oxidizing atmosphere and fired at 2000 ° C. for 20 hours to obtain a carbon-carbon composite. The change in weight before and after firing is shown in Table 2.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

As is apparent from the above table, a resin composition having a low viscosity and a high residual carbon rate can be obtained by using an aromatic aldehyde or an aromatic alcohol. Conventionally, multistage impregnation, which involves repeating the steps of impregnation, drying, and firing several times, is required. By using these, it becomes possible to simplify these steps and carry out by one-step impregnation, and a high-strength carbon-carbon composite molded article can be manufactured at low cost.

Claims (1)

[Claims] 1. A resol-type phenol resin having a molar ratio of phenols and aldehydes of 1.0 to 2.0 and a number average molecular weight of 150 to 300, and at least 3 aromatic aldehydes and / or aromatic alcohols. Carbon-carbon characterized by being obtained by impregnating carbon fiber or carbon cloth with a resole-type phenol resin composition for carbon-carbon composite used by weight% or more, heat-molding, and then firing in a non-oxidizing atmosphere. Composite molded product.