JPH04170311A - Production of vitreous carbon material - Google Patents

Abstract

PURPOSE:To efficiently obtain a vetreous carbon material free from structural defect by alternately depositing specified porous sheets and half-cured molded plates of a thermosetting resin which acts as the precursor of vitreous carbon, hot pressing the laminated body and then calcining. CONSTITUTION:A thermosetting resin which acts as the precursor of vitreous carbon (e.g. phenolic resin) is molded into plates and subjected to primary curing at 50-100 deg.C to form half-cured molded plates of >=8mm thickness. A paper essentially comprising cellulose fiber obtd. by mixing rayon fiber containing >90% alpha-cellulose with needle-leaf tree pulp and making into paper is impregnated with a thermosetting resin, dried at 50-120 deg.C and cured to obtain half-cured porous sheets 2 of 10-300mum thickness. Then the molded plates 1 and porous sheets 2 are alternately laminated, hot pressed under 1-100kg/cm<2> pressure at 140-200 deg.C to cure the resin component, and baked at >=800 deg.C in a nonoxidative atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for efficiently manufacturing a thick plate-like glassy carbon material.

[Prior art] Glassy carbon material is a carbonaceous material that has an extremely dense and homogeneous glass-like structure, and has better self-lubricating properties, gas impermeability, abrasion resistance, and surface smoothness compared to ordinary carbon materials. Because of its excellent properties, it is used as an industrial component in a variety of fields.

Generally, a glassy carbon material is manufactured by firing and carbonizing a molded precursor of a thermosetting resin having a high carbonization residual rate, such as a furan type or phenol type. Since the carbonization process proceeds in the solid phase, a large amount of volatile components generated by thermal decomposition of the precursor resin are discharged out of the solid phase, and the volume shrinks while converting into carbide. At this time, if the pyrolysis gas is not smoothly discharged from the solid phase and remains, product defects such as voids, blisters, and cracks will occur. Such stagnation of pyrolysis gas occurs more prominently when the precursor resin is thick-walled, so it has been considered difficult to produce high-quality glassy carbon material with a wall thickness of 3m11 or more. .

As a means of solving these problems, fibers with low carbonization yields such as animal fibers, vegetable fibers, and synthetic fibers are arranged in layers with thermosetting resin to make a board. A method of manufacturing a glassy carbon plate with a wall thickness of 31III or more by carbonization has been proposed (Japanese Unexamined Patent Publication No. 6
3-129070).

[Problems to be Solved by the Invention] In the method of JP-A-63-129070, the fiber layer with a low carbonization yield is first thermally decomposed to form a continuous pore structure in the firing stage, and then the thermosetting resin is The pyrolysis gas generated during the carbonization process is discharged to the outside using the continuous pores, and the gas body is smoothly removed, thereby making it possible to manufacture a thick glass-like carbon plate.

However, when using this mechanism, it is not possible to exhaust the volatile gas components generated from the thermosetting resin in the low temperature range until the fiber layer thermally decomposes, so it is difficult to control the conditions during firing and carbonization. If not precisely adjusted, defective structures may appear.8 The purpose of the present invention is to solve the problems of the prior art and to facilitate the smooth discharge of gas from the raw material resin during sintering and carbonization. An object of the present invention is to provide a method for efficiently manufacturing a glassy carbon material in the form of a thick plate.

(Problems to be Solved) A method for producing a glassy carbon material according to the present invention to achieve the above-mentioned object is to convert a semi-cured molded plate of a thermosetting resin, which is a precursor of glassy carbon, into a cellulose fiber. Paper mainly composed of is impregnated with a thermosetting resin and laminated alternately with semi-cured porous sheets, heat-press pressed to harden the resin component, and then heated to a temperature of 800°C or higher in a non-oxidizing atmosphere. The structural feature is that the firing process is performed in the area.

The type of thermosetting resin that serves as a precursor of glassy carbon is generally not limited as long as it can be converted into glassy carbon by carbonization. Typical raw resins are phenolic resins and furan resins. These thermosetting resins are used in a liquid state in the initial condensation stage, and are formed into a plate shape by an appropriate forming method such as molding, casting, or centrifugal molding, and are then primarily cured at a temperature range of 50-100°C. Create a semi-cured molded plate.

Paper mainly composed of cellulose fibers, which is the base material of porous sheets, has no particular restrictions on pore size, fiber diameter, porosity, etc. as a single structure, such as ordinary valve paper manufacturing or rayon paper manufacturing, but resin The condition is that vent holes that allow gas permeation are formed after impregnation. A suitable material that satisfies this condition is paper made by mixing rayon fiber with an α-cellulose content of 90% or more and softwood pulp. These papers are impregnated by being immersed in a thermosetting resin solution or a solution prepared by diluting this with methanol, acetone, water, or the like. The thermosetting resin used in this step does not need to be the same as the thermosetting resin that is the precursor of the glassy carbon described above, but it is desirable that both be the same resin. The paper is dried and primarily cured at a temperature range of 50 to 120°C to create a semi-cured porous sheet.

Next, as shown in FIG. 1, the semi-cured molded plates 1 made of the thermosetting resin and the semi-cured porous sheets 2 are alternately arranged and laminated and hot-pressed. The lamination conditions are such that the thickness of each semi-cured molded plate of thermosetting resin is within 13 mm, and the thickness of each porous sheet is set in the range of 100 to 300 μ-. by 10mn
It becomes possible to easily manufacture a glass-like carbon plate with a thickness exceeding +. In addition, the heat pressure conditions are as follows:
100 kg/cm'' and a heating temperature of 140 to 200°C, and the resin component is completely cured at this stage.

The laminated and hardened plate-like molded body is transferred to a heating furnace maintained in a non-oxidizing atmosphere according to a conventional method, and is heated to a temperature range of s o o'c or higher to undergo firing carbonization treatment. The material after firing and carbonization can be further graphitized at a temperature of 2000° C. or higher, if necessary.

The thermosetting resin is completely carbonized by the firing process, and the whole is converted into an integrated glass-like carbon molded body.

[For production]

According to the process of the present invention, a semi-cured molded plate of a thermosetting resin, which is a precursor of glassy carbon, and a semi-cured porous sheet made by impregnating a paper mainly composed of cellulose fibers with a thermosetting resin are used. When the sheets are alternately arranged and laminated, hot-press molded and cured, the porous sheet becomes a structure in which the porous sheet is interposed between the eyebrows as a ventilation layer through which gas components permeate. Therefore, the pyrolysis gas generated during the firing process is smoothly and quickly discharged to the outside through the ventilation layer of the porous sheet even at low temperatures.

Through this action, the phenomenon in which pyrolysis gas remains as bubbles in the solid phase is effectively avoided, and even thick materials are free from quality defects such as voids, blisters, and structural cracks. Converts into high-grade glassy carbon material.

In addition, the porous sheet layer shrinks during the firing process and becomes glassy carbon with carbonized fibers mixed in, forming an integrated structure with the adjacent glassy carbon layer, forming a homogeneous glassy carbon material as a whole. .

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

Example 1 (1) Creation of a semi-cured molded plate of thermosetting resin An initial condensate of phenolic resin (manufactured by Sumitomo Deerez ■, PR940) was poured into a flat molded container and molded, and then primary hardened at a temperature of 80°C. A semi-cured molded plate with dimensions of 250 mm in length and width and 4 mm in thickness was prepared.

(2) Creation of semi-cured porous sheet α-cellulose content 90% or more, thickness 5 denier, length 2
5m+1117) L/-Yonsen III C Yamatobo 1[1
1) 80 parts by weight and softwood pulp (NBKP) 20
Wet paper is made from the weight part, with a thickness of 200μ and an average pore diameter of 10.
A 0 μ- paper was obtained.

This paper is coated with a phenolic resin initial condensate [manufactured by Sumitomo Durez ■, Pl? 940) in a 20 wt % acetone solution, and then dried and primary hardened at a temperature of 100° C. to create a semi-cured porous sheet.

(3) Lamination molding and firing treatment Three semi-cured thermosetting resin molded plates and two semi-cured porous sheets were alternately arranged and laminated at a pressure of 10 kg/cm.
Hot pressure pressing was performed at a temperature of 180° C. for 10 minutes.

The formed integral molded body was transferred to an electric firing furnace, and fired and carbonized at a temperature of 2000° C. with the surrounding area covered with coke backing.

(4) Evaluation of glassy carbon material When the state of the 10 sheets of glassy carbon material produced in this manner after firing was investigated, the overall thickness (average) was 9. 7mm, thickness of porous sheet layer (average)
The porous sheet layer had a thick plate shape with an average pore diameter of 25 μm and an integrated homogeneous structure, and no cracks or blisters were observed during firing.

Implementation [2] Glass was molded using the same process and conditions as in Example 1, except that six semi-cured thermosetting resin molded plates and five semi-cured porous sheets were alternately arranged and laminated and molded. Ten pieces of shaped carbon material were manufactured.

This glassy carbon material has a total thickness (average) of 19.
5 mm, the thickness of the porous sheet layer (average) is 51 μm, and the pore diameter of the porous sheet layer (average) is 23 μm. I was not able to admit.

Comparative Example 1 Ten sheets of glassy carbon material were manufactured using the same process and conditions as in Example 1, except that three semi-cured thermosetting resin molded plates made in Example 1 were stacked and hot-pressed. This glassy carbon material has a total thickness (average) of 9.6
Although it was in the form of a thick plate of Vg, a blistering phenomenon was observed in 100 sheets, and firing cracks occurred in one of them.

Comparative Example 2 A semi-cured molded plate of thermosetting resin according to Example 1 was heated to 7.5@
II thickness and was completely cured at a temperature of 180"C. This molded plate was transferred to an electric furnace and directly heated to a temperature of 200"C.
Firing carbonization treatment was performed at a temperature of °C.

The obtained glassy carbon materials (10 sheets) were in the form of thick plates with a thickness (average) of 6.0 mm, but bulging was observed in two sheets, and firing cracking was observed in one sheet.

Comparative Example 3 A semi-cured molded plate of thermosetting resin according to Nl was 10m-
This was completely cured at a temperature of 180°C. This molded plate was transferred to an electric furnace and directly subjected to firing carbonization treatment at a temperature of 2000°C.

The obtained glassy carbon material ('l 0 pieces) has a thickness of [
Although the sheets were thick plates with an average diameter of 8.0+ m, all 10 sheets had a blistering phenomenon, and 8 of them had cracks during firing.

[Effects of the Invention] As described above, according to the present invention, by alternately interposing specific porous sheets during molding of thermosetting resin, even if the thickness is more than 1 (Igm), A high quality glassy carbon material without structural defects can be efficiently produced.

Therefore, this method has high industrial value as a method for manufacturing application parts that require thick walls.

[Brief explanation of the drawing]

FIG. 1 is a perspective explanatory view showing a molded state of array stacking according to the present invention. 1... Semi-cured molded plate of thermosetting resin 2... Porous sheet Applicant Tokai Carbon Co., Ltd. Agent Patent attorney Masaya Takahata

Claims (1)

[Claims] 1. A semi-cured molded plate of a thermosetting resin that is a precursor of glassy carbon is used as a porous sheet made by impregnating paper mainly made of cellulose fibers with a thermosetting resin. A method for producing a glass-like carbon material, which comprises alternately arranging and laminating the resin components, hardening the resin component by hot-pressing, and then firing the resin components in a non-oxidizing atmosphere at a temperature of 800° C. or higher. 2. The method for producing a glassy carbon material according to claim 1, wherein the thickness of the semi-cured molded thermosetting resin plate is within 8 mm, and the thickness of the porous sheet is set in the range of 10 to 300 μm.