JPH0769729A - Production of vitreous carbonaceous material - Google Patents

Abstract

PURPOSE:To obtain in high yield a vitreous carbonaceous material >6 mm in wall thickness having uniform and dense texture. CONSTITUTION:This material can be obtained by mixing carbon clusters, either directly or in the form of an organic solvent solution, with a thermosetting resin liquor convertible to vitreous carbon when carbonized and then by molding and hardening the mixture, followed by heating it in a nonoxidative atmosphere at >=800 deg.C to effect baking carbonization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a glassy carbon material having a homogeneous and dense structure, particularly a thickness of 6
The present invention relates to a method for producing a high-quality glassy carbon material having a thick shape exceeding mm with a good product yield.

[0002]

2. Description of the Related Art A glassy carbon material is a heterogeneous carbon material having a glassy and dense composition structure, and has chemical stability, gas impermeability, wear resistance, self-lubricity, compared with ordinary carbon materials. Because of its excellent surface smoothness and toughness, it is utilized for various industrial materials in various fields, such as battery electrodes, electrolysis electrodes, semiconductor manufacturing crucibles, by taking advantage of its characteristics. In recent years, paying attention to the non-contaminating material property that minute particles do not separate from the tissue,
It is being put to practical use in the field of semiconductors such as electrodes for plasma etching of silicon wafers and members for ion implantation equipment where contamination is not desired.

Generally, a glassy carbon material is produced by a method of molding a thermosetting resin liquid having a high carbonization residual carbon ratio such as a phenol type or a furan type and firing and carbonizing a cured precursor. Since the mechanism of calcination and carbonization by this process progresses in the solid phase, a process of discharging a large amount of volatile components generated by thermal decomposition of the precursor resin to the outside of the solid phase and converting into a carbide while shrinking in volume is followed. However, when the precursor is large and has a thick shape, the pyrolysis gas and condensed water are not smoothly discharged from the molded body and remain inside the tissue, which causes the generation of pores and voids, and thus the swelling of the material, This will cause material defects such as cracks. Therefore, industrially manufacturing a large-sized or thick-walled glassy carbon material is considered to be a major issue in the carbon industry, and research on it has been actively conducted.

Conventionally, as a technique for manufacturing a large or thick-walled glassy carbon material, the technique is roughly classified to select the type and properties of a thermosetting resin as a raw material, and other techniques for the thermosetting resin. A method is known in which an additive component is combined into a raw material system. Among these, the former technique includes, for example, a molecular weight of 100 or more, a viscosity of 1 to 100 poise, and a gelling time of 5 to
A method for producing a thick plate-like glassy carbon material by heat-treating a phenol resin for 60 minutes under a specific condition, followed by molding and curing and then firing and carbonizing (JP-A-4-362062) is proposed by the present applicant. However, the maximum wall thickness produced by this method is limited to about 4 mm.

Examples of the latter method include a method in which a thermosetting resin liquid and carbon powder are kneaded, extruded and roll-molded, and then calcined and carbonized (Japanese Patent Publication No. 1-27967). A method is known in which a liquid is impregnated, then laminated and molded, and then calcined and carbonized (JP-A-60-145952). According to the method using these composite raw material systems, the moldability is improved and the production of thick-walled or large-sized materials becomes easy. In particular, the method of adding carbon powder is more advantageous for obtaining a thick-walled product since it can simultaneously bring about the effect of improving the carbonization residual coal rate.

[0006]

However, in the manufacturing method using the composite raw material system, generation of fine pores due to the entrainment of air is avoided in the process of dispersing, mixing or permeating a solid substance into a liquid thermosetting resin. However, there is a defect that the structure of the glassy carbon material obtained is not uniform due to the influence of the addition of foreign components.

The present inventor has conducted various studies on substances suitable as additive components in the composite raw material system, and as a result, it has been difficult to produce the conventional carbon clusters using carbon clusters composed of molecular carbon. The present invention has been completed by finding that a glassy carbon material having a uniform and dense shape having a thick shape exceeding 6 mm can be manufactured with a good product yield.

Therefore, an object of the present invention is to provide a method for producing a glassy carbon material which has a homogeneous and dense structure and is capable of producing a thick material having a thickness of more than 6 mm with a good product yield.

[0009]

The method for producing a glassy carbon material according to the present invention for achieving the above-mentioned object is a thermosetting resin liquid which is converted into glassy carbon by carbonization, in which a carbon cluster is used as it is or as an organic compound. The composition is characterized in that the mixture is mixed in a state of being dissolved in a solvent, the mixture is molded and cured, and then the mixture is heated to a temperature of 800 ° C. or higher in a non-oxidizing atmosphere to perform a firing carbonization treatment.

The thermosetting resin liquid as the main raw material of the present invention is
The type and chemical properties are not limited as long as it is a resin material that is converted to glassy carbon by carbonization, but the most preferable resin raw material is an initial condensate of a thermosetting resin belonging to a phenol type or a furan type.

The carbon cluster as an additive component of the composite raw material system is a molecular carbon (sometimes referred to as "fullerene") having a property of collecting dozens of carbon atoms, or a functional group is added to this carbon molecule. Means molecular carbon. Currently, as a carbon cluster,
Physical properties such as C ₆₀ , C ₇₀ , C ₇₆ , and C ₇₈ are known, but the type of physical properties is not limited.

The carbon clusters are mixed with the thermosetting resin liquid as it is or in the state of being dissolved in an organic solvent to form a composite raw material system. Examples of the organic solvent used when dissolving and mixing include toluene, benzene, and carbon disulfide. It is also possible to oxidize carbon clusters with air, nitric acid or the like to form a functional group such as a carbonyl group or a hydroxyl group on the surface, which is dissolved in a polar organic solvent such as alcohol or acetone and mixed. . The blending amount of carbon clusters with respect to the thermosetting resin liquid is appropriately set in consideration of the type of the thermosetting resin used, the molding thickness, etc.
A range of 50% by weight is suitable. If the amount is less than 5% by weight, the effect of addition cannot be obtained, and if it exceeds 50% by weight, uniform mixing cannot be achieved. The mixing is performed by a stirring process, but the carbon clusters are smoothly dissolved in the resin liquid by the stirring operation.

Then, the composite raw material mixture is molded into a desired shape in consideration of the shrinkage ratio during molding and carbonization so that the finally obtained glassy carbon material has a wall thickness of 6 mm or more, and is heat-cured. Since the mixture has a liquid state, the molding operation is performed by applying a casting method or a multiple molding (overcoating) method. When cast molding is adopted, it is preferable to place it in a vacuum system and perform degassing under reduced pressure. The curing treatment after molding is performed by heating in the temperature range of 100 to 300 ° C.

The hardened precursor is placed in a heating furnace kept in a non-oxidizing atmosphere, and calcined and carbonized at a temperature in the range of 800 ° C. or higher, preferably 1000 to 2500 ° C. to give a thick glassy carbon material. To get

[0015]

The reason why it is difficult to manufacture a glassy carbon material having a thick shape is mainly due to a high residual rate of pores inside the tissue at the stage of molding the thermosetting resin liquid as a raw material. That is, the curing reaction of the thermosetting resin proceeds while generating precursor gas and condensed water by the decomposition condensation reaction, but as the molding material becomes thicker, the gas or condensed water in the center of the tissue diffuses to the outside. It becomes difficult to do, and remains as a pore inside. If there are many remaining pores, the gas stored in the pores will undergo thermal expansion during the firing and carbonization process, or physical stress will be concentrated on the pores themselves due to carbonization contraction, resulting in a decrease in tissue density, material swelling, cracking or damage. Invite.

Therefore, in order to avoid such a phenomenon, it is necessary to reduce the raw material components that are the source of the precursor gas and the condensed water as much as possible, and increase the carbon yield during firing. In this sense, a composite raw material system in which carbon powder is added and mixed with a thermosetting resin liquid is advantageous, but it is difficult to uniformly disperse this kind of solid raw material in the resin liquid, and at the time of mixing and dispersing it I can not avoid the involvement of
It may cause pores. In addition, the presence of a carbon structure different from that of glassy carbon makes the texture property non-uniform.

The carbon clusters to be added to the thermosetting resin solution in the present invention are extremely fine particles composed of molecular carbon, and since they dissolve in the resin solution or the organic solvent, they can be easily mixed in a homogeneous phase by stirring and mixing. A composite raw material system is formed. Therefore, the carbonization yield of the raw material system can be effectively increased without involving a phenomenon such as entrainment of air during the addition and mixing. By such an action, it becomes possible to efficiently manufacture a thick glassy carbon material having a homogeneous and dense structure structure without causing material defects during firing and carbonization. Specifically, the bulk density of the material is 1.50 g / cc
As described above, it is possible to obtain a thick glassy carbon material having a thickness of about 7 mm, which has characteristics of an internal pore diameter of 10 μm or less, a pore content of 5% or less, and a bending strength of 1200 kgf / cm ² or more.

[0018]

【Example】

Examples 1 to 3 and Comparative Examples 1 to 2 Phenol and formalin purified by vacuum distillation were subjected to an addition condensation reaction according to a conventional method to prepare a phenol resin initial condensate (liquid resin). Then, a predetermined amount of carbon clusters is added to the phenol resin initial condensate,
The mixture was dissolved and mixed by a stirring operation. This mixture was poured into a polypropylene vat, put in a vacuum desiccator, deaerated under a reduced pressure of 10 torr or less, and then transferred to an electric oven in a cleaning system adjusted to a predetermined oxygen concentration and heated at a temperature of 100 ° C. Hardened. The molded resin precursor was a plate having a length and width of 100 mm and a thickness of 8 mm.

Next, a high-purity graphite plate having impurities of less than 5 ppm on both sides of the precursor [G347SS manufactured by Tokai Carbon Co., Ltd.]
Sandwiched between them, and set in a packingless heating furnace (TP150 manufactured by Tokai High-Temperature Industry Co., Ltd.) with a high-purity graphite heater [G151ASS manufactured by Tokai Carbon Co., Ltd.] set, and the atmosphere in the furnace containing less than 10 ppm of impurities. A glassy carbon material having a length and width of 80 mm and a thickness of 7 mm was obtained by heating to 2000 ° C. while carrying out high-purity argon gas and heating and carbonizing. The thickness of the glassy carbon material produced in this manner, various characteristics, and the yield at the time of carbonization and firing were defined as the addition amount of carbon clusters to the phenol resin initial condensation product (indicated as "C cluster amount" in Table 1). The comparison is shown in Table 1. For comparison, no carbon clusters were added (Comparative Example 1), and graphite powder having a particle size of 100 mesh was added instead of the carbon clusters (Comparative Example 2).
However, other conditions are also shown in Table 1 regarding the characteristics and the firing carbonization yield of the glassy carbon material manufactured in the same manner as in the example.
It was also published in.

[0020]

[Table 1]

From the results shown in Table 1, in each of Examples 1 to 3, the glassy carbon material having a uniform thickness and a thickness of 7 mm and substantially dense and high strength with substantially no pores or structure defects was obtained. Well manufactured. On the other hand, in Comparative Example 1 in which no carbon cluster was added, both the material properties and the product yield were significantly reduced, and in Comparative Example 2 in which graphite powder was added, the product yield was good, but It was confirmed that the number of pores increased and the homogeneity and compactness decreased.

[0022]

As described above, according to the present invention, by using a composite raw material system in which carbon clusters composed of molecular carbon are added to a thermosetting resin liquid, a thickness of more than 6 mm having a homogeneous dense structure can be obtained. It becomes possible to manufacture a meat-like glassy carbon material with an excellent product yield. Therefore, it is extremely useful as a technique for producing a glassy carbon material for a member for use that is thick and requires high material characteristics.

Claims (1)

[Claims] 1. A thermosetting resin liquid which is converted into glassy carbon by carbonization is mixed with a carbon cluster as it is or in a state of being dissolved in an organic solvent, and the mixture is molded and cured, and then 800 ° C. in a non-oxidizing atmosphere. A method for producing a glassy carbon material, which comprises heating to the above temperature and carrying out a firing carbonization treatment.