JPH0769730A - Production of vitreous carbonaceous material - Google Patents

Abstract

PURPOSE:To obtain in high yield a vitreous carbonaceous material > 4mm in wall thickness with uniform and dense texture. CONSTITUTION:A thermosetting resin liquor of high residual carbon rate is molded and cured and then baked and carbonized in a nonoxidative atmosphere at >=800 deg.C to effect conversion into the objective vitreous carbonaceous material. In this method, the curing is conducted in such a state that the resin molded form is suspended in a gas flowing atmospheric system pref. at room temperature to 300 deg.C with a variation in temperature within + or -3 deg.C.

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 microstructure, and particularly a plate thickness of 4
The present invention relates to an industrial manufacturing method for producing a thick plate-like glassy carbonaceous material 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 dense structure structure, and is gas impermeable, wear resistant, corrosion resistant, self-lubricating and has a smooth surface as compared with general carbon materials. Since it is excellent in durability and robustness,
Utilizing these characteristics, it is useful for various industrial members in various fields such as battery electrodes, electrolysis electrodes, semiconductor manufacturing crucibles. In recent years, focusing on the property of non-contaminating material that does not allow fine particles to be separated from the tissue, it has been put to practical use in the semiconductor field such as electrodes for plasma etching of silicon wafers and members for ion implantation equipment where contamination is disliked. ing.

Generally, a glassy carbon material is produced by a method of molding a thermosetting resin liquid having a high carbonization residual ratio such as a phenol type and / or furan type, and firing and carbonizing the cured molded body in a non-oxidizing atmosphere. To be done. Since the firing carbonization process in this process proceeds in the solid phase, the volatile components generated in large quantities by the thermal decomposition of the resin molded product are discharged to the outside of the solid phase, and the process of converting into the carbide while the volume shrinks is followed. However, if the resin molded body is thick, pyrolysis gas, condensed water, etc. are not smoothly discharged from the molded body and remain in the tissue, which causes generation of pores and voids, and This causes defects such as swelling and cracking of the material. Therefore, it has been difficult to industrially manufacture a glassy carbon material having a plate thickness of 3 mm or more by the conventional technique.

As a means for solving such a problem,
For example, fibers having a low carbonization yield such as animal fibers, plant fibers, and synthetic fibers are arranged in a layer with a thermosetting resin to form a plate, and by carbonizing this, a glassy carbon plate having a wall thickness of 3 mm or more A method for manufacturing a
63-129070). However, this method cannot discharge the volatile gas components generated from the thermosetting resin in a low temperature range until the fiber layer is pyrolyzed, so that unless the condition control during firing and carbonization is adjusted very strictly, there is a defect. The appearance of the organization is inevitable. In addition, the glassy carbon material manufactured by interposing the fibrous substance of this kind has a drawback that the material is likely to be inhomogeneous because the material is not a single structure, especially for applications requiring a uniform material structure. However, there is a shortage of properties.

The inventors of the present invention, as an alternative technique for producing a thick plate-like glassy carbon material, use a phenol resin having a molecular weight of 100 or more, a viscosity of 1 to 100 poise and a gelation time of 5 to 60 minutes in an amount of 50 to 100. A method has already been developed in which heat treatment is carried out in the temperature range of ℃ for 5 hours or more, followed by molding and curing, followed by firing and carbonization in an atmosphere of non-oxidizing gas (Japanese Patent Laid-Open No. Hei 4)
-362062 publication).

[0006]

According to the above-mentioned prior art, it becomes possible to manufacture a thick glassy carbon plate having a single structure and having a thickness of more than 4 mm without causing a material defect. However, if the plate thickness is 5 mm or more, many material abnormalities such as cracking, chipping, and swelling of the structure occur in the firing carbonization stage, and there is a problem that product yield is reduced.

The present invention was completed as a result of multi-faceted research on curing treatment conditions for resin moldings, which is particularly problematic in the process of manufacturing a thick-plate glassy carbon material, and has a plate thickness of 5 mm. Even if it is above, it aims at providing the industrial manufacturing method which can produce a high quality glassy carbon material excellent in a homogeneous dense structure with a good product yield.

[0008]

In order to achieve the above object, a method for producing a glassy carbon material according to the present invention comprises forming a thermosetting resin liquid having a high residual carbon rate, performing a curing treatment, and then nonoxidizing. In a method of converting into a glassy carbon material by firing and carbonizing at a temperature of 800 ° C. or higher in a neutral atmosphere,
The structural feature is that the resin molding is cured in a state of being suspended in a gas flow atmosphere system.

A thermosetting resin liquid having a high residual carbon rate is used as the raw material of the present invention. The residual carbon rate of the thermosetting resin refers to the weight of carbon content remaining when the resin is fired at a temperature of 800 ° C. in a non-oxidizing atmosphere.
Resins of not less than wt% are suitable raw materials for the glassy carbon material. Such a thermosetting resin with a high residual coal rate,
For example, a phenol resin, a furan resin, a polyimide resin, etc. can be mentioned.

However, the most preferable raw material system for the purpose of the present invention is a resin composition in which a furan or a derivative compound thereof is mixed with a phenol resin having a molecular weight of 100 or more and a gelation time of 5 to 60 minutes. A phenol resin having a molecular weight of 100 or more is effective for obtaining a glassy carbon material having a high tissue strength, and a property resin having a gelation time in the range of 5 to 60 minutes gives a curing rate which is preferable in operation. Mixing furan or a derivative compound thereof to form a two-component resin composition is an element for improving the carbonization yield at the time of carbonization by firing, and the carbonization yield of 40 to 60% is usually 65 to 65%. It is possible to improve up to 75%. As the furan derivative compound, those having a furan ring in the chemical structure and compatible with the phenol resin are used. Typical compounds include furfuryl alcohol, furfural, and furancarboxylic acid methyl ester, which may be used alone or in combination of two or more. The mixing ratio of these furan-based components to the phenol resin is appropriately determined according to the resin properties, but is generally set within the range of 5 to 50% by weight.

The thermosetting resin liquid used as a raw material is molded into a desired plate shape in consideration of the shrinkage ratio so that the finally obtained glassy carbon material has a wall thickness of 4 mm or more. Molding is
For example, means such as molding, injection molding, cast molding, and multiple molding (overcoating) can be applied.

The main constituent feature of the present invention is that the plate-shaped resin molding is subjected to a curing treatment in a state of being suspended in a gas flow atmosphere system. The state of being suspended in the gas flow atmosphere system means a state in which the whole or most of the resin molded body is held in an atmosphere system in which gas continuously flows without contacting other members. This state is, for example, a method of rapidly and evenly ejecting a gas from the lower part of a flat plate having porous or innumerable through holes, and holding a plate-shaped resin molded body in a floating state on the gas jet flow, or a resin It can be formed by a method of vertically suspending in a gas flow atmosphere system that rises or descends while holding the end portion of the molded body.

At this time, the type of gas flowing is not particularly limited, and air or nitrogen is usually used. But,
In order to accelerate the curing smoothly and increase the product yield, it is preferable to use a gas having a composition containing an oxygen component at a concentration of 16 to 85% in the gas. The temperature of the gas is
The temperature can be arbitrarily set within the range of room temperature to 300 ° C., but it is preferable that the curing treatment operation is carried out while controlling the temperature within a range of ± 3 ° C. with respect to the set temperature. If the gas temperature exceeds 300 ° C, the curing speed will proceed too rapidly, and if there is a temperature difference exceeding the set temperature ± 3 ° C, unevenness of the structure will occur inside the cured product and cracks will occur during firing in the post process. It may cause deformation or deformation.

The resin molding thus formed is
It is packed in a heating furnace kept in a non-oxidizing atmosphere and subjected to calcination and carbonization treatment in a temperature range of 800 ° C. or higher. The material after firing and carbonization is
2000 ° C under the same non-oxidizing atmosphere as above if necessary
Graphitization is performed at the above temperature to obtain a thick plate-like glassy carbon material.

[0015]

[Function] Generally, in the process of manufacturing a glassy carbon material, the plate-shaped resin molded body is cured by placing it on a flat graphite plate to prevent deformation of the resin molded body or by sandwiching it between the flat graphite plates to heat-cure it. The method is effective. However, in the case of using these curing means, condensed water or decomposition gas generated inside the tissue of the resin molded body to be treated at the time of curing can be smoothly released outside the tissue by being blocked by the graphite plate in surface contact. become unable. For this reason, as the wall thickness of the resin molded body increases, the degree to which condensed water and decomposed gas are occluded in the structure increases, which causes generation of fine bubbles and firing cracking and deformation due to inhomogeneity of the structure. In addition, when the method of sandwiching with graphite plates is adopted, the surface of the resin molded body may be damaged when the graphite plate that is in close contact with the surface is cured and contracted, or the phenomenon that free contraction is exerted and stress is applied to the tissue may occur. To do.

According to the present invention, since the hardening process proceeds in a state where the resin molded body is suspended in the gas flow atmosphere system, condensed water and decomposed gas generated in the tissue during the hardening process are prevented by the external member. Instead, it diffuses out of the tissue from three-dimensional directions. Therefore, it does not occlude and remain as fine bubbles inside the structure, and the occurrence of defect phenomena such as cracking and deformation during firing is effectively reduced. Furthermore, since the curing operation is performed in the non-contact state where the support member is not in contact with or in close contact in the shrinking process, distortion of the tissue and occurrence of scratches on the surface do not occur. Through such an action, it becomes possible to industrially produce a plate-like glassy carbon material having a uniform thickness of more than 4 mm and 5 mm or more with a good yield.

[0017]

EXAMPLES Examples of the present invention will be described in detail below in comparison with comparative examples, but the scope of the present invention is not limited to these examples.

Examples 1 to 3 Phenol purified by vacuum distillation and formalin were subjected to an addition condensation reaction in the presence of ammonia to prepare a phenol resin initial condensate having a molecular weight of 132 and a gelation time of 14 minutes. Add 3 parts of furfuryl alcohol to this phenol resin solution.
0% by weight was added and mixed to prepare a resin composition having a viscosity of 40 poise and a resin content of 55%.

This resin composition was poured as a raw material resin liquid into a polypropylene vat, put in a vacuum desiccator, deaerated under a reduced pressure of 10 torr or less, and then transferred to a clean electric oven maintained at a predetermined oxygen concentration. 80 ℃
The plate-shaped molded body was obtained by leaving it at room temperature for 24 hours. Then, the resin molded body was placed on the gas injection device having a structure in which flat aluminum plates having through holes with a diameter of 2 mm formed at equal intervals were laid on the upper surface of the closed container-shaped gas collection part,
Air heated to 50 ° C. was injected under pressure. At this stage, the press-fitted air continuously ejected from the through hole to the upper part, and the resin molded body floated on the air jet in a horizontal state. This floating state 2
Curing treatment was carried out for 4 hours while floating in the gas distribution atmosphere system.

Then, the hardened plate-shaped compact was sandwiched between high-purity graphite plates (G347SS manufactured by Tokai Carbon Co., Ltd.) having an impurity content of less than 5 ppm, and packingless high-temperature heating equipped with a high-purity graphite heater was used. It was set in a furnace [TP150 manufactured by Tokai Kogyo Kogyo Co., Ltd.] and heated to 2000 ° C. while maintaining the atmosphere in the furnace with high-purity argon gas containing less than 10 ppm of impurities to carry out calcination and carbonization. Thus, glassy carbon plates having a wall thickness of 4 mm, 5 mm, and 6 mm were manufactured, and various property characteristics and the yield (20 samples) at the time of carbonization by firing were measured. The results are shown in Table 1.

Comparative Examples 1 to 3 Instead of the curing treatment operation according to Examples 1 to 3, graphite plates having a thickness of 10 mm on both sides of the resin molding were manufactured by Tokai Carbon Co., Ltd.
347] and placed in a hot air dryer at 150 ° C. and left for 24 hours for curing treatment. Other than that, glassy carbon materials having wall thicknesses of 4 mm, 5 mm, and 6 mm were manufactured under the same conditions as in Example 1, and various characteristics of each of the obtained glassy carbon materials and the yield (20 samples) at the time of carbonization by firing are shown in Table 1. It was also published in.

[0022]

[Table 1]

From the results shown in Table 1, according to the examples of the present invention, the high-quality thick plate-like glassy carbon material can be efficiently produced, and the product yield can be obtained even with the glassy carbon material having a thickness of 6 mm. It was confirmed that it was well obtained. On the other hand, it is found that the glassy carbonaceous material of the comparative example is inferior in both property characteristics and yield in the same thickness.

Example 4 Glass-like carbon having a thickness of 4 mm was prepared under the same conditions except that the curing treatment was carried out in a gas flowing atmosphere system using nitrogen gas heated to 150 ° C. instead of air. A board was manufactured. The properties of this glassy carbon material are as follows: average pore diameter 2 μm, pore content 1%, bulk density 1.4.
The firing carbonization yield was 76% at 5 g / cc and bending strength of 1120 kgf / mm ² .

[0025]

As described above, according to the present invention, it is possible to efficiently manufacture a thick plate-like glassy carbon material having high strength and excellent homogeneous and dense structure by improving the curing process. It will be possible. Therefore, it is extremely useful as an industrial manufacturing technology for glassy carbon materials for members for the semiconductor field and the like, which require a thickness of more than 4 mm and high material properties.

Claims (2)

[Claims] 1. A thermosetting resin liquid having a high residual carbon rate is molded,
After the curing treatment, in a method of firing carbonized at a temperature of 800 ° C. or higher in a non-oxidizing atmosphere to convert into a glassy carbon material, the curing treatment may be carried out in a state in which the resin molding is suspended in a gas flow atmosphere system. A method for producing a glassy carbon material characterized. 2. The temperature of the gas flow atmosphere system is from room temperature to 30.
The method for producing a glassy carbon material according to claim 1, wherein the hardening treatment is carried out under a temperature condition within a range of 0 ° C and within a set temperature ± 3 ° C.