JP3487472B2 - Method for producing Si-containing glassy carbon material - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a modified glassy carbon material having a homogeneous and dense composite structure structure containing a Si component as a continuous phase, and particularly a Si-containing glassy carbon material having excellent oxidation resistance. Manufacturing method.

[0002]

2. Description of the Related Art A glassy carbon material is a heterogeneous carbon material having a macroscopically vitreous and dense structure obtained by firing and carbonizing a thermosetting resin compact, Due to its excellent gas impermeability, wear resistance, corrosion resistance, self-lubricating property, surface smoothness and robustness,
Utilizing its characteristics, it is useful for various industrial members in various fields. In recent years, focusing on the non-contaminating material properties that do not cause minute carbon particles to separate from the tissue, practical applications in the semiconductor field such as electrodes for plasma etching of silicon wafers and members for ion implantation equipment that do not like contamination have been developed. Has been.

However, the glassy carbon material is fragile in material, and has a material defect peculiar to the carbon material in that, like the general carbon material, the oxidation rapidly progresses in a high temperature oxidizing atmosphere to deteriorate the physical properties. Therefore, it has been attempted to improve the physical properties by compounding a ceramic component in a glassy carbon structure. In the initial stage, a method was used in which ceramic particles such as SiC were mixed with a thermosetting resin as a raw material by a dry method or a wet method, and a molded body obtained by curing this was carbonized by firing. Cannot be uniformly dispersed in the carbon structure, and grain boundaries exist between the ceramic particles and the carbon structure.Therefore, under severe conditions of use, there is a problem of material destruction or separation of ceramic particles. It was

For this reason, there has been proposed a method of obtaining a Si-containing glassy carbon material having a uniform structure by mixing a silicon-containing compound with a thermosetting resin to prepare a raw material system. For example, JP-A-61-1111 discloses a liquid silicon compound,
Disclosed is a method for producing an oxidation resistant carbon material by carbonizing a liquid organic compound having a functional group and carbonized by heating, and a precursor substance containing Si, O and C in which a catalyst for polymerization or crosslinking is solubilized. Has been done. In this method, a silicic acid polymer obtained by dealkalization of water glass as a liquid silicon compound, an ester of a silicic acid with an organic compound having a hydroxyl group, a Si ester such as ethyl silicate, a reaction product of silicon tetrachloride and ethanol, etc. The use of sulfuric acid, hydrochloric acid, organic peroxides, organic sulfonic acids, etc. as a catalyst is an essential requirement.

However, the above-mentioned method is intended to produce a carbon material containing a relatively large amount of Si component (C / Si atomic ratio: 0.5 to 19). Due to the large amount, the silicon compounds bond with each other in the process of forming the precursor material containing Si, O and C to form fine agglomerates, which are the same as S in the carbonized structure.
i It tends to have a non-uniform texture that is dispersed as a granular material. Also, multiple S such as siloxane bond (Si-0-Si)
Even when a polymerized ester in which i atoms are chained is used as a silicon source, a heterogeneous structure is likewise caused by agglomeration.
Even if the blending amount with respect to the liquid organic compound is reduced, it is not possible to obtain a continuous phase carbonaceous structure in which Si is not dispersed in a particle state. In addition, when the catalyst used in combination is a strong acid such as sulfuric acid or hydrochloric acid, the gelation reaction proceeds rapidly and the homogeneity of the structure is impaired, and when using a catalyst such as sodium ethylate or organic sulfonic acid, the contained inorganic components remain. It becomes an impurity and becomes a factor to reduce the purity.

JP-A-5-43319 discloses a glassy state in which ultrafine ceramics obtained by uniformly mixing a thermosetting resin and an organometallic compound in a liquid state and heating (calcining) are highly dispersed. A carbon composite material is disclosed.
In the present invention, as the organometallic compound serving as a silicon source, S
Polycarbosilanes and polysilanes that give iC, Si
A Ti-containing polycarbosilane which gives —Ti—C—O, S
Polysilazanes that give i _x N _y , Si—N—C or Si ₃ N ₄ —SiC have been used. However, when a polymer such as polycarbosilane or polysilane having a plurality of silane bonds is mixed with a thermosetting resin to form a raw material system, the ceramics source is in a state of being dispersed as a molecule, so that fine metal carbide particles and fine particles are formed after heat treatment. It is unavoidable that grain boundaries are generated, and a glassy carbon structure in which ceramics and carbon exhibit a homogeneous continuous phase cannot be obtained.

In addition, Japanese Patent Laid-Open No. 5-339006 discloses a polymerization or cross-linking catalyst which uses a liquid silicon compound and a liquid organic compound which has a functional group and produces carbon by heating as a raw material, and uniformly solubilizes it. A β-type silicon carbide-carbon mixture, which is obtained by subjecting the resulting precursor substance to heating or carbonization in a non-oxidizing atmosphere and further firing the resulting intermediate product at a higher temperature in a non-oxidizing atmosphere. In the method for producing a powder, the raw material and the catalyst do not substantially contain an impurity element, the intermediate molded product has a carbon / silicon molar ratio of 2.5 to 3.5, and the carbonization in the mixed powder is Silicon and carbon are homogeneously mixed, the amount of carbon is 3 to 28% by weight, and the content of each impurity element in the mixed powder is 1 pp.
A method for producing a high-purity β-type silicon carbide-carbon mixed powder having a size of m or less has been proposed. However, this method is for producing a SiC-C-based powder for a sintered body, and is not a production technique for a Si-containing carbon compact whose main component is a glassy carbon structure.

In view of the above situation, the present applicant has previously proposed -O-
Obtained by firing and carbonizing a molded body of a thermosetting resin crosslinked with Si-O-, and atomic level Si is distributed as a uniform continuous phase in the range of 0.1 to 15% by weight in the glassy carbon structure. The SiC-containing glassy carbon material having a texture property, a thermosetting resin, and a hydrolyzate of a Si alkoxide having a single Si atom in one molecule are stirred and mixed in an organic solvent to produce a crosslinking reaction. A method (Japanese Patent Application No. 7-155177) was developed, in which the gelled product obtained by (1) is cured and molded, and then the cured molded body is subjected to firing and carbonization treatment at a temperature of 800 ° C. or higher in a non-oxidizing atmosphere. 1
An aminosilane compound containing a single Si atom in the molecule is dropped into a thermosetting resin solution and mixed by stirring to mold and cure the mixed solution, and then the cured molded article is heated in a non-oxidizing atmosphere at 80
We proposed a method for producing a Si-containing glassy carbon material, which is characterized by performing a firing carbonization treatment at a temperature of 0 ° C. or higher (Japanese Patent Application No. 7-234696).

[0009]

When an aminosilane compound containing a single Si atom in one molecule is selected as the Si source, a relatively large Si-containing glassy carbon material in which Si is homogeneously dispersed in the tissue at the atomic level. Can be manufactured. However, in this raw material system, the amino group is extremely likely to react with the thermosetting resin, so that various reaction troubles are likely to occur. That is, in the process of mixing the aminosilane compound and the thermosetting resin, the amino group in the raw material is bonded to the thermosetting resin in preference to the alkoxy group, and the dehydration condensation reaction proceeds rapidly while generating heat, resulting in a resin viscosity Promotes degassing failure and local distortion due to rise in temperature.

The above phenomenon causes cracks and damages in the structure of the Si-containing glassy carbon material obtained as a result, and is a major obstacle to ensuring a high product yield in industrial production. This problem can be solved by giving operating conditions that suppress the reaction between the aminosilane compound and the thermosetting resin, but it is not easy to give operating conditions that forcefully suppress the reaction without lowering the product yield. .

The present inventors have conducted multifaceted research on a Si source that has the same effect as an aminosilane compound but does not cause the above-mentioned reaction trouble, and as a result, an epoxy containing a single Si atom in one molecule. It was confirmed that when a silane compound was used as the Si source, it did not react with the thermosetting resin, and a Si-containing glassy carbon material having oxidation resistance could be efficiently produced without causing a reaction trouble.

The present invention has been developed on the basis of the above-mentioned findings, and an object of the object to be solved is a high oxidation resistance S having a uniform and dense composite structure structure in which Si is distributed as a continuous phase.
An object of the present invention is to provide a method for industrially producing an i-containing glassy carbon material with a high level of product yield.

[0013]

A method for producing a Si-containing glassy carbon material according to the present invention for solving the above-mentioned problems is obtained by thermosetting an epoxysilane compound containing a single Si atom in one molecule. After dropping the resin composition into the resin liquid and stirring and mixing, and molding and curing the obtained epoxysilane-containing resin composition into a predetermined shape, the molded body is subjected to firing and carbonization treatment at a temperature of 800 ° C. or higher in a non-oxidizing atmosphere. This is a feature of the configuration.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an epoxysilane compound is a raw material component serving as a Si source for dispersing and compounding Si in a glassy carbon structure at the atomic level, and an epoxysilane compound containing a single Si atom in one molecule. Is used selectively. In the case of polysilane in which two or more Si atoms are bonded in one molecule, the Si source is in the state of being dispersed as a polymer, so that the aggregation phenomenon easily occurs at the mixing stage with the thermosetting resin liquid, and the Si dispersion at the atomic level is generated. It becomes impossible.

An epoxysilane compound containing a single Si atom in one molecule is represented by the following general formula (1) (wherein R ₁ is a saturated carbon chain or cyclic carbon chain containing one oxygen, R ₂ or R ₃ And R ₄ is an alkyl group or an alkoxy group having 1 to 3 carbon atoms.).

[0016]

[Chemical 1]

Examples of such epoxysilane compounds include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3
-Glycidoxypropyldimethylethoxysilane, 3-
Glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldiisopropenoxysilane,
Examples thereof include 3-glycidoxypropyldiisopropylethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. However, 3-glycidoxypropylmethyldimethoxysilane is most preferably used for the purposes of the present invention. The reason for this is that the 3-glycidoxypropylmethyldimethoxysilane has a low molecular weight, and therefore has a relatively small amount of volatile components during carbonization, which is advantageous in that material distortion due to shrinkage does not occur.

The above-mentioned epoxysilane compound containing a single Si atom in one molecule (hereinafter, simply referred to as "epoxysilane compound") is dropped into the thermosetting resin liquid. The thermosetting resin liquid serves as a carbon source which is converted into glassy carbon by firing and carbonizing treatment, and for example, liquid phenolic resin, furan resin, polyimide resin, polycarbodiimide resin, polyacrylonitrile resin, pyrene- A phenanthrene-based resin, a polyvinyl chloride-based resin, an epoxy-based resin, a mixed resin thereof, or the like can be used. In particular, an initial condensate of a phenolic resin or a furan resin having a high residual carbon rate remaining when the resin is fired at a temperature of 800 ° C. in a non-oxidizing atmosphere, or a mixed resin liquid thereof is preferably used.

The dropping of the epoxysilane compound into the thermosetting resin liquid is carried out under sufficient stirring conditions. At this time, since the reaction between the epoxysilane compound and the thermosetting resin does not occur, reaction troubles such as heat generation and thickening of the mixed resin composition do not occur. Therefore, it is not particularly necessary to perform complicated reaction suppressing operations such as cooling, sufficient fluidity can be ensured even when a large amount of epoxysilane compound is dropped, and air entrained during mixing can be easily degassed, so that voids It becomes possible to mold without leaving. Even when a silane compound having an alkoxy group is used, the reaction between the alkoxy group and the resin hardly occurs at this point, so that the phenomenon of deterioration of workability due to gelation does not occur.

The epoxysilane-containing resin composition obtained by the dropping operation is preferably stored in a fluid state for one day or more in order to further enhance the uniformity of mixing and promote the dispersion at the atomic level. Mixtures stored in a low-viscosity fluid form have a very homogeneous compositional state in which Si is dispersed at the atomic level. Separation of silane compounds that occurs when mixing silane compounds having only hydrophobic groups such as methyl groups, etc. Does not occur.

The epoxysilane-containing resin composition is then vacuum deaerated, if necessary, to remove the stored air, and then molded into a predetermined shape. The molding means is usually cast molding or centrifugal molding, but it is also possible to apply compression molding, extrusion molding, transfer molding, etc. at the semi-cured stage. The molded body thus molded is heated to a temperature of 70 to 150 ° C. and hardened to obtain a glassy carbon precursor.

The epoxysilane compound which has not reacted with the thermosetting resin during the room temperature mixing process undergoes a ring-opening reaction of the epoxy group at the heating stage during molding and curing to start the reaction with the resin component. Therefore, by controlling the heating temperature in the molding process, the epoxysilane compound slowly reacts with the resin component while maintaining a uniform dispersion state, and the curing reaction of the resin and the reaction of the epoxy group and the resin component occur at the same time during the curing process. proceed. By this action, the curing reaction of the resin proceeds at a slow rate, so that the occurrence of strain due to the reaction between the epoxysilane compound and the resin component is effectively suppressed.

For example, the reaction between the epoxysilane compound and the phenol resin is presumed to proceed according to the reaction formula shown in the following chemical formula 2.

[0024]

[Chemical 2]

Then, the cured molded article is transferred to a heating furnace kept in a non-oxidizing atmosphere and subjected to a calcination carbonization treatment in a temperature range of 800 ° C. or higher, preferably in a temperature range of 1000 to 2500 ° C. The thermosetting resin component is converted into glassy carbon at the stage of the firing carbonization treatment.

The Si-containing glassy carbon material produced in the above process is a carbonaceous structure which is obtained by substantially carbonizing a thermosetting resin compact by firing.
i has a composite texture property in which it is distributed as a uniform continuous phase in the glassy carbon structure. This texture is Si
Unlike the composite structure in which the components are dispersed in the form of fine particles, it exhibits an alloy-like continuous solid solution phase in which there are no grain boundaries between Si and C, and macroscopically it has a structure structure of glassy carbon alone. Substantially no difference was observed, while microscopically, it had a unique composite morphology in which a part of C of the glassy carbon structure was substituted and bonded to Si. In particular, according to the present invention, a high-quality Si-containing glassy carbon material having high strength and high oxidation resistance with no material defects even in a high compounding region in which the Si content in the glassy carbon structure exceeds 5% by weight. Can be obtained with high product yield.

[0027]

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

Examples 1 to 4 3-glycidoxypropylmethyldimethoxysilane [AY43-026 manufactured by Toray Dow Corning Silicone Co., Ltd.] A phenol resin at room temperature using a viscosity of 3.4 cp (25 ° C.) as a Si source. Initial condensate [Sumitomo Dures Co., Ltd., PR-940]
The mixture was dropped into a viscosity of 400 cp (25 ° C.), and the stirring and mixing operation was continued for 1 hour. At this time, the dropping amount was changed so that the Si content in the glassy carbon structure finally became about 5, 7, 1
It was set to be 0,15% by weight. Subsequently, the mixture was allowed to stand at room temperature for 45 hours in a fluidized state while being slowly stirred to improve the homogeneity of the liquid. Then, the mixed resin composition is poured into a mold and subjected to defoaming treatment in a vacuum device, and then 70
The mixed resin composition was cured by heating to ~ 150 ° C. Table 1 shows the temperature and viscosity of the mixed resin composition after stirring and mixing for 1 hour, the viscosity of the mixed resin composition when flowing into the mold, and the presence or absence of pores in the obtained cured molded product. As shown in Table 1, the viscosity of the mixed resin composition hardly changed, and the obtained cured molded article was effectively defoamed and no bubbles were observed. This cured molded product was transferred to a heating furnace maintained in a nitrogen atmosphere, and heated at a heating rate of 10 ° C./hr for 20
It was heated to 00 ° C and carbonized by firing. In this way Si
Si-containing glassy carbon materials with different contents (200 m in length and width)
m, thickness 5 mm). In each of the Si-containing glassy carbon materials obtained, no cracks or pores were observed in the structure, and the surface condition was a glassy smooth surface.

[0029]

[Table 1]

The bulk density, bending strength and oxidation resistance at high temperature of each Si-containing glassy carbon material obtained were measured,
The results are shown in Table 2. In addition, the results of evaluating the product yield are also shown in Table 2. The oxidation resistance was shown as a weight loss rate when the test piece was treated with a dry air flow at a temperature of 950 ° C. for 60 minutes. The product yield is the yield (%) excluding material defects such as cracks and cracks in the product structure per 100 specimens.

Example 5 A 3-glycidoxypropyldiisopropylethoxysilane having a viscosity of 2.9 cp (25 ° C.) was used as a Si source, and the other conditions were the same as in Example 1 except that the initial condensation product was dropped into the phenol resin initial condensate. By stirring and mixing for a time, a Si-containing glassy carbon material having a Si content of about 10 wt% was manufactured. The temperature and viscosity of the mixed resin composition after stirring and mixing for 1 hour, the viscosity of the mixed resin composition when flowing into the mold, and the presence or absence of bubbles in the cured molded article are also shown in Table 1. Was almost unchanged, and the cured molded product obtained was effectively defoamed and no bubbles were observed. Further, in the obtained Si-containing glassy carbon material, no cracks or pores were observed in the structure, and the surface condition was smooth. Various properties of the obtained Si-containing glassy carbon material were measured, and the results are also shown in Table 2.

Comparative Examples 1 to 3 3-Aminopropyltriethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) A viscosity of 1.5 cp (25 ° C.) was used as a Si source, and this was used at room temperature to carry out a phenol resin initial condensation product [Sumitomo Dures Co. PR-940] manufactured by K.K., and the stirring and mixing operation was continued for 1 hour. At this time, the dropping amount was changed so that the final Si content in the glassy carbon structure was about 5, 10, and 15% by weight. Then immediately in the refrigerator (2
C.) and cooled for 18 hours to suppress the reaction between the amino group and the resin component. Then, the mixture was allowed to stand in a fluidized state for 24 hours while being slowly stirred at room temperature, and the homogeneity of the liquid was enhanced. Next, the mixed resin composition was flown into a mold, subjected to defoaming treatment in a vacuum device, and then heated to 70 to 150 ° C. to cure the mixed resin composition. Table 1 also shows the temperature and viscosity of the mixed resin composition after stirring and mixing for 1 hour, the viscosity of the mixed resin composition when flowing into the mold, and the presence or absence of bubbles in the obtained cured molded article. From Table 1, the mixed resin composition after stirring and mixing for 1 hour caused a reaction during mixing to generate heat, an increase in temperature and an increase in viscosity were observed, and the viscosity of the mixed resin composition when flowing into the mold significantly increased. Was recognized. Further, the obtained cured molded article was not effectively defoamed, and bubbles were observed. This cured molded body was transferred to a heating furnace maintained in a nitrogen atmosphere, heated to 2000 ° C. at a temperature rising rate of 10 ° C./hr, and carbonized. In this way, Si-containing glassy carbon materials with different Si contents (vertical and horizontal)
200mm, thickness 5mm) was manufactured. In each of the obtained Si-containing glassy carbon materials, cracks and cracks occurred in a part of the structure during the manufacturing process, and the product yield declined. Table 2 also shows various characteristics of each Si-containing glassy carbon material.

Comparative Example 4 Trimethylethoxysilane (manufactured by Fulka) was used as a Si source, and the phenol resin initial condensate [Sumitomo Dures Co., Ltd.] was used at room temperature at an amount ratio such that the Si content was about 10% by weight. Manufactured by PR-940], and the stirring and mixing operation was continued for 1 hour. When the molding was performed under the same conditions as in Example 1 after that, innumerable bubbles were generated inside the structure of the molded body, and it was not possible to obtain a Si-containing glassy carbon material having no pores.

[0034]

[Table 2]

From the results shown in Table 2, the Si-containing glassy carbon material obtained by the manufacturing method of the present invention has a bending strength and acid resistance higher than those of the comparative example products having the same Si content by the manufacturing method which deviates from the conditions of the present invention. It is recognized that both the chemical conversion properties are improved and the product yield is significantly improved.

[0036]

Industrial Applicability As described above, according to the present invention, an Si-containing glassy carbon material having a homogeneous and dense composite structure containing an atomic level Si component as a continuous phase and having excellent oxidation resistance is industrially produced. Can be manufactured. Especially S
It is possible to obtain a high-quality Si-containing glassy carbon material with no material defects at a high product yield rate even under manufacturing conditions with a high i-content, so that desorption of fine particles from the structure and oxidative damage do not occur. Even in harsh conditions that tend to occur, a sufficiently stable use condition is guaranteed. Therefore, it is extremely useful as a manufacturing technique of industrial members for various fields of application including semiconductor members.

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Claims (2)

(57) [Claims] 1. An epoxysilane compound containing a single Si atom in one molecule is dropped into a thermosetting resin liquid and mixed with stirring to mold and cure the obtained epoxysilane-containing resin composition into a predetermined shape. After that, the molded body is placed in a non-oxidizing atmosphere for 8 hours.
A method for producing a Si-containing glassy carbon material, which comprises performing a carbonization treatment by firing at a temperature of 00 ° C or higher. 2. The method for producing a Si-containing glassy carbon material according to claim 1, wherein the epoxysilane compound containing a single Si atom in one molecule is 3-glycidoxypropylmethyldimethoxysilane.