JPH10167826A - Production of vitreous carbon material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of a vitreous carbon material having a homogeneous and dense structure, impermeability for gases and >6mm thickness by a simple method with a good production yield. SOLUTION: One or more kinds of monomers, prepolymers and low mol.wt. polymers of a thermosetting resin which converts into vitreous carbon by carbonization is mixed with a carbon black having <=20nm average primary particle size and <=100ml/100g oil absorption of dibutyl phthalate measured by a mechanical method as it is or uniformly dispersed in an org. solvent. The mixture is compacted, hardened and then calcined for carbonization by heating at >=800 deg.C in an inert gas atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a glassy carbon material having a homogeneous and dense structure, and more particularly to a simple method for producing a high-quality glassy carbon material having a thickness exceeding 6 mm. The present invention relates to a method for producing a product with high yield using the same.

[0002]

2. Description of the Related Art In general, a vitreous carbon material is a heterogeneous carbon material having a vitreous dense structure, and has chemical stability, gas impermeability, abrasion resistance, and self-lubrication compared to ordinary carbon materials. Because of its excellent properties, surface smoothness, and robustness, it is used for various industrial materials in various fields in addition to electrodes for batteries, electrodes for electrolysis, crucibles for semiconductor production, and the like, utilizing its properties. In recent years, attention has been paid to non-contaminating material properties that do not allow minute particles to detach from the tissue, and practical use in the semiconductor field where contamination is averse, such as electrodes for plasma etching of semiconductor manufacturing equipment and members for ion implantation equipment. Is planned.

In general, a glassy carbon material is produced by molding a monomer, prepolymer or low polymer of a thermosetting resin having a high carbonization residue such as a phenol-based or furan-based carbon, and calcining and curing the cured precursor. Is done. Since the mechanism of calcined carbonization by this process proceeds in the solid phase, a large amount of volatile components generated by the thermal decomposition of the precursor resin is discharged out of the solid phase, and is converted into carbide while contracting the volume. However, if the precursor is large and thick, the pyrolysis gas or condensed water remains in the tissue without being discharged smoothly from the molded body, which causes pores and voids, which in turn causes the material to swell. Material defects such as cracks will be caused. For this reason, industrially producing large and thick glassy carbonaceous materials is regarded as a major issue in the carbon industry, and researches are being actively conducted.

Conventionally, techniques for producing a large or thick glassy carbon material include a method of roughly selecting the type and properties of a thermosetting resin to be a raw material, and a technique of adding another type of thermosetting resin to a thermosetting resin. There is a method of compounding the additive components to form a raw material system. Among them, the former method includes, for example, a molecular weight of 100 or more, a viscosity of 1 to 100 poise, and a gelation time of 5 to 6
0 minute phenolic resin is heat-treated under specific conditions,
A method of producing a thick plate-like glassy carbon material by forming and hardening and then calcining and carbonizing (Japanese Unexamined Patent Publication No. 4-362062).
However, in order to obtain a thick product exceeding 4 mm, strict control of manufacturing conditions is required, and a long manufacturing period is required.

[0005] As the latter method, many proposals have been made because the method of adding carbon powder has a large effect of improving the carbonization residual carbon ratio and is advantageous for obtaining a thick product. For example, a method in which a thermosetting resin liquid and a carbon powder are kneaded, extruded and roll-formed, then calcined and carbonized (Japanese Patent Publication No. 1-27967), and a method using carbon black as the carbon powder (Japanese Patent Application Laid-Open No. 64-24071) ),
There is a method of mixing (A) a thermosetting resin, (B) a cured powder of (A) and (C) carbon black, molding and carbonizing or graphitizing (Japanese Patent Publication No. 45-11004).

However, when a composite raw material system such as carbon powder as described above is used as a method for producing a glassy carbon material, there is an advantage that the thickness and size of the product can be increased by improving the moldability. On the other hand, there are problems such as a decrease in gas impermeability and a lack of a uniform structure inherent to glassy carbon.

Further, a method of uniformly dispersing a thermosetting resin liquid in carbon fine powder such as carbon black, applying mechanical energy thereto to induce a mechanochemical phenomenon, uniformly kneading the mixture, and firing after infusibilizing treatment. (JP-A-58-145608) has been proposed.

However, this method requires a strict kneading step and a powder compression molding step after uniformly dispersing the raw material mixture, and the steps are complicated and long, so that the production cost is extremely high. There is.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a highly dense, gas-impermeable, glass-like carbon material having a wall thickness exceeding 6 mm by using a simple method with a good product yield. It provides a method that can be manufactured.

[0010]

Under such circumstances, the present inventors have conducted intensive studies and as a result, have found that the average basic particle diameter and the amount of dibutyl phthalate oil absorption by a mechanical method within a specified range are added to the thermosetting resin liquid. It is found that if black is mixed and subjected to firing and carbonization after molding and hardening, glassy carbon having a thickness of more than 6 mm and a thickness of about 9 mm can be produced with good production yield with uniform denseness and excellent gas impermeability, with a high production yield. The present invention has been completed. That is, the present invention relates to one or more of a monomer, a prepolymer and a low polymer of a thermosetting resin which is converted into glassy carbon by carbonization, an average basic particle diameter of 20 nm or less, and dibutyl phthalate oil absorption by a mechanical method. 0.1 to 50% by weight of carbon black having an amount of 100 ml / 100 g or less
It is intended to provide a method for producing a glassy carbon material, which comprises mixing, molding and curing the mixture, and then firing and carbonizing in an inert gas atmosphere.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As the thermosetting resin monomer, prepolymer and low polymer (hereinafter referred to as thermosetting resin liquid) used in the present invention, any resin material which is converted into glassy carbon by carbonization can be used. If not particularly limited, phenol resin precondensate, furan resin precondensate, furfuryl alcohol, furfural, diphenyl oxide, unsaturated polyester resin and the like, among them,
Furan resin precondensates and phenol resin precondensates are preferred from the viewpoints of moldability, shape stability during firing, carbonization reaction rate, and the like. The monomer, prepolymer and low polymer of the thermosetting resin can be used alone or in combination of two or more.

The carbon black as an additive component of the composite material system used in the present invention has an average basic particle diameter of 20 nm or less and a dibutyl phthalate oil absorption (hereinafter referred to as DBP oil absorption) by a mechanical method of 100 ml / 100 g or less. It is. The average basic particle size is defined in ASTM D3849.
It is measured according to -89 and refers to the arithmetic average particle diameter of primary particles of fine powder. DB by mechanical method
The P oil absorption is determined in accordance with JIS K6221 oil absorption A method. Average basic particle size is 20nm, DBP
If the oil absorption exceeds 100 ml / 100 g, the tissue tends to be heterogeneous and the gas impermeability is reduced. A more preferable range of the DBP oil absorption is 50 to 100 ml / 100 g.

In the present invention, the method of mixing the thermosetting resin liquid with the above-mentioned carbon black is not particularly limited, and a method in which carbon black is added to the thermosetting resin liquid as it is and then mixed mechanically, Are mixed in a state of being uniformly dispersed in an organic solvent, added to the thermosetting resin liquid, and then mechanically mixed. When carbon black is dispersed in an organic solvent in advance, the compounding amount of the carbon black is 10 to 10 in the organic solvent.
About 15% by weight is appropriate. If it exceeds 15% by weight, it will not be uniformly dispersed, and if it is less than 10% by weight, the organic solvent will not be sufficiently volatilized, causing a problem. Further, as the organic solvent,
For example, alcohols that evaporate at a relatively low temperature, such as methanol and ethanol, may be mentioned. The amount of the carbon black is appropriately set in consideration of the type of the thermosetting resin to be used, the molding thickness, and the like.
It is preferred to be in the range of 1 to 50% by weight. If the amount is less than 0.1% by weight, the effect of addition cannot be obtained, and 50% by weight.
If it exceeds 300, uniform mixing cannot be performed.

The method of mechanically mixing the thermosetting resin liquid and the carbon black is not particularly limited, but examples include a method of uniformly dispersing and mixing with a two or three roll mill, a ball mill, a Banbury mill and a colloid mill. Can be At this time, a heating operation may be added as necessary, or a curing agent such as a thermosetting resin may be blended. The mixture obtained by the above operation is obtained in a state of a liquid substance, a semi-fluid substance, or the like, but a deaeration operation or a deaeration operation may be added as necessary.

Next, the mixture may be shaped so that the desired glassy carbon material has a desired thickness and a thickness of 6 mm or more. Examples of the molding method include methods such as cast molding, multiple molding (overcoating), extrusion molding, injection molding, and meeting roll molding. In the case of the casting molding method, it is preferable to sufficiently perform a vacuum degassing treatment in a vacuum system.

After molding, it is preferable to carry out a curing treatment, preferably in a heating oven at 150 ° C. or higher, preferably 150 ° C. to 300 ° C.

Thereafter, the cured precursor is baked in a heating furnace in an atmosphere of an inert gas such as argon or nitrogen to be carbonized. The firing conditions are not particularly limited,
The carbonization may be performed by heating at a temperature of 800 ° C. or higher, preferably 1000 to 2800 ° C., and then cooling to obtain the desired thick glassy carbon material.

The reason why it is difficult to produce a glassy carbon material having a thick shape is mainly due to an increase in the residual ratio of pores existing inside the tissue at the stage of molding a thermosetting resin liquid as a raw material. That is, in the curing reaction of the thermosetting resin, the precursor gas or the condensed water by the decomposition condensation reaction becomes difficult to diffuse to the outside, and remains as pores inside. If there are many remaining pores, the gas occluded in the pores undergoes thermal expansion in the firing carbonization process, and physical stress concentrates on the pores themselves due to carbonization shrinkage, resulting in a decrease in tissue density, swelling, cracking or breakage of the material Invite. Therefore, in order to avoid such a phenomenon, it is necessary to reduce the raw material components as sources of precursor gas and condensed water as much as possible and to increase the carbon yield during firing. In this sense, a composite raw material system in which carbon powder is added to and mixed with a thermosetting resin liquid is advantageous. On the other hand, when the particle size of this kind of solid raw material is large, it is difficult to uniformly disperse the resin material in the resin liquid, and when mixing and dispersing, entrainment of air cannot be avoided, which causes pores. This is a disadvantage. The glassy carbon produced by the composite raw material system has a non-uniform texture due to the presence of a heterogeneous carbon structure, and this non-uniformity causes particles. In the present invention, by adding carbon black having a specific property to the thermosetting resin liquid, the carbonization yield of the raw material system can be effectively increased without inhibiting the structure of the glassy carbon. .

[0019]

According to the present invention, it is possible to effectively produce a thick glass-like carbon material having a gas-impermeable structure with a homogeneous and dense structure. Specifically, the bulk density is 1.5 g
A glassy carbon material having a thickness of not less than 6 mm and a gas permeability of 10 ⁻⁹ cm ² / sec (nitrogen gas) having a characteristic of not less than / CC can be obtained.

[0020]

Next, the present invention will be described in detail with reference to examples, but this is merely an example and does not limit the present invention at all.

Examples 1-4, Comparative Examples 1-5 Phenol and formalin purified by vacuum distillation were subjected to an addition condensation reaction according to a conventional method to prepare a phenol resin precondensate (liquid resin). Next, the phenolic resin precondensate has an average basic particle diameter of 15 and 19 nm and DBP oil absorption of 70, 80 and 90 ml / 100 g by a mechanical method.
0.5, 1, 25 and 49% by weight of carbon black having the following properties were added and mechanically mixed using a three-roll mill. The mixture was poured into a polypropylene vat, placed in a vacuum desiccator, degassed under a reduced pressure of 10 torr or less, then transferred to a heating oven in a cleaning system adjusted to a predetermined oxygen concentration, and heated to a temperature of 100 ° C. Hardened. The molded precursor is 170 mm long and 110 mm wide.
mm, and a plate-like body having a thickness of 9, 8, 7 mm, respectively. Then, both surfaces of the precursor were sandwiched between high-purity graphite plates having impurities of less than 5 ppm, and the precursor was set in a packingless heating furnace also equipped with a high-purity graphite heater.
While maintaining with high purity argon gas of less than 0 ppm, 200
It was heated to 0 ° C. and calcined to give a glassy carbon material having a length of 140 mm, a width of 90 mm and a thickness of 8, 7, and 6 mm, respectively. Table 1 shows the thickness, structure and gas permeability of the glassy carbon material thus obtained. In addition,
For comparison, DB by mechanical method with an average basic particle diameter of 19 nm
Carbon black having properties of P oil absorption of 90 ml / 100 g was added at 0.05 and 53 wt% (Comparative Example 1,
2) 1% by weight of carbon black having an average basic particle diameter of 25 nm and having a DBP oil absorption of 110 ml / 100 g by a mechanical method (Comparative Example 3);
Dibutyl phthalate oil absorption by mechanical method at 9nm 130ml
/ 100 g of carbon glass having a property of 1 wt% (Comparative Example 4) and those without carbon black (Comparative Example 5) were prepared in the same manner as in Examples except for the other conditions. Table 1 shows the results
It was also attached to.

[0022]

[Table 1]

In the table, “○” in the thickness of the product indicates no cracking due to carbonization or graphitization, and “X” indicates cracking due to carbonization or graphitization. In addition, the structure was observed by an electron microscope (SEM) at a magnification of 5000. “Homogeneous” indicates that the particles were vitreous and the presence of particles could not be confirmed, and “heterogeneous” confirmed local aggregation of carbon particles. A thing. Also,
The gas permeability refers to the amount of nitrogen gas permeated under a pressure of 1 kg / cm ² .

From Table 1, it can be seen that in Examples 1-4, a homogeneous, dense, gas-impermeable, glassy carbon material having a thickness of at least 6 mm and substantially no pores or structural defects was produced. Well manufactured. On the other hand, in Comparative Examples 1 to 5, it was recognized that both the material properties and the product yield were significantly reduced, and the homogeneity was also reduced.

Claims (1)

[Claims] 1. An oil having an average basic particle diameter of 20 nm or less, a dibutyl phthalate oil absorption by a mechanical method, in one or more of a monomer, a prepolymer, and a low polymer of a thermosetting resin which is converted into glassy carbon by carbonization. 100ml / 100
g of carbon black having a property of 0.1 to 50 g or less.
A method for producing a glassy carbon material, comprising: mixing by weight, molding and hardening the mixture, and then firing and carbonizing in an inert gas atmosphere.