JP3396116B2 - 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] 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, and is gas-free compared to general carbon materials. Because of its excellent permeability, abrasion 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.

[0003]

2. Description of the Related Art However, a glassy carbon material is fragile in its material and, like a general carbon material, has a material defect peculiar to a carbon material that is rapidly oxidized in a high temperature oxidizing atmosphere and deteriorates its physical properties. is there. 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 because grain boundaries exist between the ceramic particles and the carbon structure, material destruction may occur under severe usage conditions,
There is a problem that the phenomenon that the ceramic particles come off occurs.

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 ₂ 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. After curing and molding the gelled product obtained by the above method, a method (hereinafter referred to as "prior art") of firing and curing the cured molded body at a temperature of 800 ° C. or more under a non-oxidizing atmosphere was developed.
Proposed as No. 7.

[0009]

According to the above-mentioned prior art, a thermosetting resin as a glassy carbon source and a hydrolyzate of a Si alkoxide having a single Si atom in one molecule as a Si source are used. By carrying out a crosslinking reaction in a state of being uniformly mixed, -O-Si-O- is obtained as a gelled product exhibiting a homogeneous continuous phase bonded to a methylol group of a thermosetting resin, and the gelled product is cured and molded and then fired. By carbonizing, it becomes possible to convert Si at the atomic level into glassy carbon having a unique composite texture structure in which atomic level Si is distributed as a uniform continuous phase.

However, when the Si content is increased in this method, the reaction between Si alkoxides preferentially proceeds to facilitate dimerization and mass increase, and in particular, large-sized molded articles are prepared using tetraethoxysilane as a silicon source. If this is attempted, there is a problem in that aggregation occurs in the dispersion system and cracks occur in the structure during gelling and hardening. In addition, since a large amount of organic solvent must be used in the manufacturing process, shrinkage due to solvent volatilization during the molding and curing process is severe, and it becomes difficult to obtain a molded product with high dimensional accuracy, and the organic solvent inside the tissue. There is also a problem that pores (pores) remain due to the non-uniform volatilization.

The present inventor has conducted extensive studies to solve the above-mentioned problems remaining in the prior art, and as a result, has a silane having an amino group as a silicon source and containing a single Si atom in one molecule. When a compound is selected and directly mixed with a thermosetting resin liquid without the interposition of solvents to cause a slow polymerization reaction, an agglomeration phenomenon due to a siloxane bond is not generated, and even when a large molded body is formed. The fact that a Si-containing glassy carbon material having a composite structure without cracks, pores and dimensional deformation and having Si uniformly dispersed in the structure at the atomic level is obtained has been clarified.

The present invention was developed on the basis of the above findings, and a first object of the present invention is to provide a uniform and dense composite structure structure in which Si component is distributed as a continuous phase and which is excellent in oxidation resistance. It is to provide a method for producing a Si-containing glassy carbon material. A second object is to provide a method for industrially manufacturing a large Si-containing glassy carbon material having the above properties without cracks or structural defects.

[0013]

In order to achieve the above object, a method for producing a Si-containing glassy carbon material according to the present invention comprises a thermosetting resin liquid containing an aminosilane compound containing a single Si atom in one molecule. The main technical feature is that the mixture is dropped into the mixture, stirred and mixed, and the mixed solution is molded and cured, and then the cured molded body is calcined and carbonized at a temperature of 800 ° C. or higher in a non-oxidizing atmosphere.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A thermosetting resin serves as a carbon source which is converted into glassy carbon by a firing carbonization treatment. For example, a liquid phenol resin, furan resin, polyimide resin, polycarbodiimide resin, poly Examples thereof include acrylonitrile-based resin, pyrene-phenanthrene-based resin, polyvinyl chloride-based resin, epoxy-based resin, and mixed resins thereof. In particular, the resin should
Phenol-based resin or furan-based resin that has a high residual carbon ratio when baked at a temperature of 00 ° C., and that when mixed with a silicon source component, the amino groups in the silane compound act to cause a slow dehydration condensation reaction. The initial condensate or a mixed resin liquid thereof is preferably used.

As the silicon source, an aminosilane compound containing a single Si atom in one molecule is selectively used. 1
In the case of polysilane in which two or more Si atoms are bonded in the molecule, the agglomeration phenomenon easily occurs at the mixing stage with the thermosetting resin liquid,
In addition, organic functional groups other than amino groups, such as methyl groups and vinyl groups, do not react directly with the thermosetting resin, so they may separate during the mixing process, or they may associate with each other or polymerize (polymerize) to form atoms. It becomes impossible to disperse Si at the level.

The aminosilane compound containing a single Si atom in one molecule is represented by the following general formula (Formula 1), and is usually
It is commercially available as an amine-based silane coupling agent.

[0017]

[Chemical 1]

As the amine-based silane coupling agent containing an alkoxy group, 3-aminopropyltriethoxysilane (SiC ₉ H ₂₃ NO ₃ ), N- (2-aminoethyl) -3 is used.
-Aminopropyltrimethoxysilane (SiC ₈ H ₂₂ N ₂ O ₃ ),
N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane (SiC ₈ H ₂₂ N ₂ O ₂ ), p- [N- (2-aminoethyl) aminomethyl] phenethyltrimethoxysilane (SiC ₁₄ H _{2 6} N ₂ O _3), 4- aminobutyl dimethylmethoxysilane _{(SiC 7 H 19 NO),} 4- aminobutyl triethoxysilane _{(SiC 10 H 2 5 NO 3} ), N- (2- aminoethyl) -3
-Aminopropyltris (2-ethylhexiso) silane
(SiC ₂₉ H _{6 4} N ₂ O ₃ ), p-aminophenyltrimethoxysilane (SiC ₉ H ₁₅ NO ₃ ), p-aminophenyltriethoxysilane (SiC ₉ H ₁₅ NO ₃ ), 3- (1-amino Propoxy) 3,3
-Dimethyl-1-propenyltrimethoxysilane (SiC ₁₁
H _{2 5} NO _4), 3- aminopropyl tris (methoxyethoxy) silane _{(SiC 18 H 4 1 NO 9} ), 3- aminopropyldimethylethoxysilane _{(SiC 7 H 19 NO),} 3- aminopropyl methyl diethoxy Silane (SiC ₈ H ₂₁ NO ₂ ), 3-aminopropyltrimethoxysilane (SiC ₉ H ₂₃ NO ₃ ), ω-aminoundecyltrimethoxysilane (SiC ₁₄ H _{3 3} NO ₃ ), 1-
Trimethoxysilyl-2- (p, m-aminomethyl) phenylethane (SiC ₁₂ H _{2 1} NO ₃ ), 6- (aminohexylaminopropyl) trimethoxysilane (SiC ₁₂ H _{3 0} N ₂ O ₃ ), N
- (triethoxysilylpropyl) urea (SiC ₁₀ H _{1 4} N
₂ O _4), trimethoxysilylpropyl diethylene triamine _{(SiC 10 H 2 7 N 3} O 3) , etc. are exemplified.

Examples of the amine-based silane coupling agent containing no alkoxy group include 3-aminopropyltrimethylsilane (SiC ₆ H ₁₇ N) and 3-aminopropyldiethylmethylsilane (SiC ⁸ H ²¹ N). To be

It is preferable to use these aminosilane compounds having a molecular weight as low as possible because organic components other than Si are thermally decomposed and volatilized during carbonization. Therefore, the most suitable amino group-containing silane compound for the present invention is 3
-Aminopropyltriethoxysilane.

The above-mentioned aminosilane compound containing a single Si atom in one molecule (hereinafter, simply referred to as "aminosilane compound")
Is dropped directly into the thermosetting resin liquid and stirred and mixed. The dropping amount of the aminosilane compound is such that the Si content in the glassy carbon structure is 0.1 to 15 finally.
The weight is adjusted to be in the range of preferably 2.0 to 10% by weight. If the Si content is less than 0.1% by weight, the combined effects such as improvement in oxidation resistance will be insufficient, and 1
If it exceeds 5% by weight, Si in the structure will be granulated and grain boundaries will occur, and the continuous phase at the atomic level will collapse, resulting in desorption of fine particles and reduction in mechanical strength.

When the drop-wise mixing proceeds at this stage, the amino functional group in the aminosilane compound is bonded to the thermosetting resin in preference to the alkoxy group, and the dehydration condensation reaction proceeds. For example, when 3-aminopropyltriethoxysilane is dropped into a phenol resin solution and mixed with stirring, the following chemical formula 2
And a two-step reaction as shown in Chemical formula 3 proceeds.

[0023]

[Chemical 2]

[0024]

[Chemical 3]

Through the above reaction, the aminosilane compound becomes a solution having a homogeneous composition in which it is uniformly dispersed in the thermosetting resin. At this stage, the alkoxy group in the aminosilane compound scarcely reacts with the thermosetting resin, and the form in which the amino group is bonded to the resin component is relatively reactive due to the enormous molecule centering on Si. Will fall. For this reason, the reaction between the alkoxy group and the resin component is suppressed, and at the same time, the aggregation caused by the polymerization of aminosilanes is suppressed, so that the mixed solution exhibits an extremely homogeneous continuous phase containing no aggregated particles.

Since the aminosilane compound is heated in the process of mixing with the thermosetting resin liquid, if the state is left as it is, the curing reaction proceeds and the heterogeneous composition is easily mixed and dispersed. In order to avoid such a phenomenon, it is preferable that the solution after mixing is cooled and stored to suppress the curing reaction, and then a slow flow is applied to enhance the homogeneity of the mixed state.

The mixed solution is subjected to vacuum deaeration as necessary to remove the stored air, and then molded. The molding means is usually cast molding or centrifugal molding, but compression molding, extrusion molding, transfer molding or the like can be applied at the semi-cured stage. The molded body is 7
It is cured by heating to a temperature of 0 to 150 ° C.

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

The Si-containing glassy carbon material thus obtained is a carbonaceous structure obtained by firing and carbonizing a thermosetting resin compact, and Si at the atomic level is carbonized of the thermosetting resin. It has a composite texture property that is distributed as a uniform continuous phase in the glassy carbon texture converted by. Unlike the structure in which the Si component is dispersed in the form of fine particles, this texture shows an alloy-like continuous solid solution phase in which there is no grain boundary between Si and C, and macroscopically glassy carbon is present. Substantially no difference from the single microstructure is observed, while microscopically a part of the glassy carbon microstructure C
Has a unique composite form in which Si is substitutionally bonded.
Due to such peculiar texture properties, the Si content is 0.1 to 1
A relatively small amount ratio of 5% by weight (C / Si atomic ratio = about 21
˜2333), it functions to effectively improve the oxidation resistance without impairing the strength characteristics, and a stable use state is exhibited even under severe conditions without particles falling off.

[0030]

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 6 and Comparative Example 1 Phenolic resin initial condensate [P, P, manufactured by Sumitomo Dures Co., Ltd.]
R-940] was introduced into a stirring tank, 3-aminopropyltriethoxysilane [TSL8345 manufactured by Toshiba Silicone Co., Ltd.] was added dropwise while stirring in a water bath, and the stirring and mixing operation was continued for 1 hour. At this time, the dropping amount of 3-aminopropyltriethoxysilane was changed stepwise so that the final Si content in the glassy carbon structure was 0 to 17% by weight. Stir and mix the solution in the refrigerator (2
C.) for 18 hours under cooling and then again gently stirred at room temperature in a stirring tank to keep the solution in a fluidized state for 24 hours. This mixed solution was poured into a mold, defoamed in a vacuum device, and then heated to 70 to 150 ° C. to cure and mold. The obtained cured molded article was transferred to a heating furnace maintained in a nitrogen atmosphere and heated at a temperature rising rate of 10 ° C./hr for 20 hours.
It was heated to 00 ° C and carbonized by firing. In this way Si
Si-containing glassy carbon materials with different contents (300 m in length and width)
m, thickness 5 mm). No cracks or pores were found in the structure of the obtained Si-containing glassy carbonaceous materials, and the surface condition was extremely smooth.

The bulk density, bending strength and oxidation resistance at high temperature of each obtained Si-containing glassy carbon material were measured,
The results are shown in Table 1. The oxidation resistance was shown as the weight loss rate when the sample was treated in dry air at temperatures of 750 ° C. and 950 ° C. for 40 minutes.

[0033]

[Table 1]

From the results shown in Table 1, the products of the Examples are all Si.
It is confirmed that the oxidation resistance is effectively improved as compared with the non-containing Comparative Example. However, if the Si content is 15% by weight
In Examples 5 and 6 above, although the oxidation resistance was good, the phenomenon that the material strength was lowered was observed.

Example 7 3-aminopropyltriethoxysilane was replaced with 3-aminopropyldiethylmethylsilane, and the others were changed to Example 1
Under the same conditions as above, a Si-containing glassy carbon material having a Si content of 5.0% by weight was manufactured. The bulk density of this material is 1.59
The g / cc and bending strength were 1063 kg / cm ² , and the weight loss rate due to oxidation was 0.2% by weight when treated at 750 ° C. and 4.0% by weight when treated at 950 ° C.

Comparative Example 2 S-aminopropyltriethoxysilane was changed to vinyltriethoxysilane, and otherwise S was used under the same conditions as in Example 8.
An Si-containing glassy carbon material having an i content of 5.0% by weight was manufactured. In this example, a part of the silicon source component was separated from the resin at the stage of molding and curing, and unevenness was generated on the surface of the molded product, and the surface of the obtained product was also observed to have unevenness indicating the inhomogeneity of the structure. The bulk density of this material is 1.56 g / cc, the bending strength is 920 kg / cm ² , and the weight loss rate due to oxidation is 75.
0.5% by weight when treated at 0 ° C, 12.1% when treated at 950 ° C
The weight percentage was inferior to the product of the present invention.

Comparative Example 3 3-aminopropyltriethoxysilane was changed to dimethyldiethoxysilane, and the other conditions were the same as in Example 8 except that S was used.
An Si-containing glassy carbon material having an i content of 5.0% by weight was manufactured. In this example, a part of the silicon source component dimerizes and separates from the resin at the stage of molding and curing, and unevenness occurs on the surface of the molded product, and the unevenness phenomenon indicating the inhomogeneity of the structure is also observed on the surface of the obtained product. Admitted. The bulk density of this material is 1.51 g /
cc, bending strength is 1048 kg / cm ² , and the weight loss rate due to oxidation is 2.4% by weight at 750 ° C treatment and 50.5% by weight at 950 ° C treatment, which is higher than that of the present invention. It was extremely inferior in sex.

[0038]

As described above, according to the present invention, it is possible to industrially manufacture a Si-containing glassy carbon material having a homogeneous and dense composite structure containing a Si component as a continuous phase and having improved oxidation resistance. it can. Therefore, it is possible to maintain a sufficiently stable use state even under severe conditions where desorption of fine particles from the tissue and oxidative damage are disliked, so it is extremely useful as an industrial member for various application fields including semiconductor members. It is useful.

Claims (3)

(57) [Claims] 1. An aminosilane compound containing a single Si atom in one molecule is dropped into a thermosetting resin liquid, and the mixture is stirred and mixed, and the mixed solution is molded and cured, and then the cured molded product is subjected to a non-oxidizing atmosphere. A method for producing a Si-containing glassy carbon material, which comprises performing a calcination carbonization treatment at a temperature of 800 ° C. or higher below. 2. The method for producing a SiC-containing glassy carbon material according to claim 1, wherein the aminosilane compound containing a single Si atom in one molecule is 3-aminopropyltriethoxysilane. 3. The SiC according to claim 1, wherein the mixed solution of the thermosetting resin liquid and the silane compound is cooled and stored to suppress the curing reaction, and then a slow flow is applied to enhance the homogeneity of the mixed state. Method for producing contained glassy carbon material.