JP2700798B2 - Manufacturing method of carbon and graphite materials - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a carbon / graphite material having a small thermal expansion coefficient and a high thermal shock strength.

(Prior art) Conventionally, carbon and graphite materials are heat-resistant materials such as rocket nozzles and gas turbine parts, brake materials for aircraft and high-speed vehicles, friction materials such as clutches, corrosion-resistant materials such as electrodes or reactors, or nuclei. It is used as a wall material for fusion reactors, and is made of carbonaceous aggregates such as graphite, calcined coke, raw coke, and carbon black, as well as thermoplastic binders such as coal-based pitch or synthetic pitch from polyvinyl chloride. Are kneaded, molded and then fired to graphitize. Therefore, the physical properties of carbon / graphite materials are greatly dependent on the state of the grain boundaries of the aggregate, for example, carbon / graphite in which the aggregate and the binder are firmly bound by making the aggregate finer and increasing its surface area. Although the material is obtained, if the particle size of the aggregate is too small, for example, 1 μm or less, the viscosity of the binder does not sufficiently decrease at the time of kneading with the binder, so that unnecessary volatile components are not removed at the time of kneading. The desired product cannot be obtained. Therefore, in order to improve the leakage of the aggregate and the binder, a method of coating a binder (pitch) on an aggregate of about 5 μm dispersed in a solvent, a method of coating a soft pitch in which the aggregate is dispersed, or And a method of graft-polymerizing styrene or methyl methacrylate using a functional group or radical on the surface of carbon black as an aggregate. However, microscopic observation of the carbon-graphite materials obtained by these methods shows that each aggregate is heat-treated in a state where each aggregate is dispersed using a single binder as a matrix. And a single layer exhibiting graphitizing behavior, and the properties of the resulting product will retain the properties of the binder used.

That is, for example, a graphite material obtained when a thermoplastic material such as pitch is used as a binder has a small electric resistance and good thermal conductivity and excellent workability, but the binder softens during the carbonization process. However, there is a drawback that the molded product is deformed or foamed, and the characteristics are distributed in the direction of gravity. On the other hand,
When a thermosetting material such as phenolic resin is used, it has the advantage that it is easy to obtain an isotropic product due to its high mechanical strength, but it has a large size to show large shrinkage during the carbonization process. Is difficult to obtain.

(Issues to be solved) The present inventor has made various studies to improve the above-mentioned drawbacks and to produce a carbon graphite material having inconsistent characteristics, and as a result, grafted heterogeneous aromatic materials to the aggregate surface in a solvent. It has been found that a high quality carbon / graphite material is obtained by polymerization, and the present invention has been completed.The object of the present invention is to provide a carbon / graphite material having a small thermal expansion coefficient and a large thermal shock strength, for example. An object of the present invention is to provide a method for producing carbon / graphite which has compatible physical properties.

(Means for Solving the Problems) That is, according to the present invention, a carbonaceous aggregate, an aromatic raw material, a catalyst, and a crosslinking agent are mixed and stirred in a solvent to form a uniform dispersion, and then heated to form a carbon aggregate surface. Graft polymerization of the aromatic raw material, the obtained reaction product is again graft-polymerized with an aromatic raw material different from the aromatic raw material, a catalyst and a crosslinking agent, and the obtained reaction product is separated from the solvent and dried. A method for producing a carbon / graphite material, comprising: forming a powdery molding raw material; firing the molded raw material; and adding the aromatic raw material, a catalyst, and a cross-linking agent to a solvent, and stirring the mixture. After the molded article made of carbonaceous aggregate was immersed and impregnated in the solution, the mixture was heated to graft-polymerize an aromatic material on the surface of the carbonaceous aggregate, and the obtained molded article was again subjected to the aromatic treatment. Aromatic raw materials different from raw materials, catalysts and A method for producing a carbon / graphite material, comprising reacting with a crosslinking agent and graft-polymerizing, taking out the obtained molded body from a solution, and baking by heating and pressing.

 Further, the present invention will be described in detail.

The carbonaceous aggregate used in the present invention may be any one as long as it is used as an aggregate in a conventional carbon / graphite material. For example, raw coke, mesocarbon microbeads, calcined coke, carbon black, artificial and natural Graphite and the like, the average particle size of which is 0.1 to 5
The present invention is an effective means especially for ultrafine particles of 1 μm or less, although the range of 00 μm is suitable. The form of the aggregate used in the present invention may be any form such as granular, porous, flat, short fiber, long fiber, etc. Thereafter, the molded body may be immersed and impregnated with a solution comprising an aromatic raw material, a catalyst and a cross-linking material.

As the aromatic raw material, petroleum-based pitch and coal-based pitch used as binders in conventional carbon / graphite materials, as well as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, styrene,
Those selected from perylene, coronene, tar, heavy oil, and derivatives having these as main skeletons can be used. Phenol, naphthol, resorcin, phloroglucin, thiophenol, oxidized pitch and the like can be used as aromatic raw materials containing oxygen and sulfur in the molecule.
In particular, in the present invention, it is effective to stack a reaction product composed of an aromatic raw material containing oxygen and sulfur in the molecule and a reaction product composed of an aromatic raw material containing neither.

That is, a reaction product composed of an aromatic raw material having oxygen and sulfur in the molecule shows a large shrinkage at the time of carbonization, and gives so-called non-graphitizable carbon. Gives graphitizable carbon.

In the present invention, by laminating these reaction products having different carbonization behaviors on the surface of the aggregate, it is possible to produce a carbon / graphite material having inconsistent physical properties such as high strength and a low coefficient of thermal expansion. .

Examples of the aromatic cross-linking agent include an aromatic compound having one or more aromatic rings having two or more aromatic rings, such as P-
Xylylene dichloride, P-xylylene glycol (1,4-benzenedimethanol), dimethyl-P-xylylene glycol, dimethyl-m-xylylene glycol, and the like can be used. In addition, aromatic compounds having at least one aldehyde group, for example, benzaldehyde, terephthalaldehyde and the like can also be used.

As for the usage ratio of the aromatic raw material and the crosslinking agent, the ratio (molar ratio) of the aromatic raw material / crosslinking agent is in the range of 1.0 to 3.0, preferably 1.25 to 2.0.

Examples of the acid catalyst include Lewis acids such as aluminum chloride and boron fluoride, or protic acids such as sulfuric acid, phosphoric acid, organic sulfonic acids and carboxylic acids, and mixtures of one or more selected from derivatives thereof. Can be used.

The amount of catalyst used depends on the reactivity of the aromatic raw material,
Generally, the catalyst / crosslinking agent (molar ratio) is in the range of 0.01 to 0.5.

The heating reaction conditions of the present invention are from room temperature to 180 ° C, especially 1 ° C.
Since the temperature range is from 00 to 130 ° C., the solvent used is preferably one having a boiling point of at least 130 ° C. Then, it must be one that dissolves the reaction components and hardly remains in the reaction product. Solvents used for such requirements are tetralin, methylnaphthalene,
Examples thereof include anthracene oil, heavy oil, o-, m-, and p-xylene, and tetralin, o-, and m-xylene are preferable from the viewpoint of reaction yield and handling.

The amount of the solvent used is determined in consideration of the reaction yield (solubility of the polymer), the curing yield of the product, and the carbonization yield. That is, the reaction yield increases as the raw material concentration (aromatic raw material + crosslinking agent) increases, but the curing yield and carbonization yield generally decrease on the higher concentration side. Usually, 300 parts by weight of the solvent is determined as a rough guide for 10 parts by weight of the aromatic raw material + crosslinking agent and 10 parts by weight of the skeleton. The same applies to the amount of solvent used in the second reaction.

The reaction time in the solvent is about 0.2 to 2 hours, and a fine precipitate is formed as the reaction proceeds.

The amount to be coated on the bone is determined as follows. That is, the amount of coating in a certain reaction system is obtained by subtracting the low molecular weight fraction remaining in the condensation water and solvent generated by the condensation reaction from the total amount of the aromatic raw material and the crosslinking agent. Can be determined in proportion to the value of. In the present invention, the coating amount largely depends on the aggregate particle size and the ease of impregnation, but is generally about 30 to 200 with respect to 100 parts by weight of the aggregate.

To compare the graft reaction of the present invention with the case without solvent,
Considering the fact that the reaction starts even at a very low catalyst amount in the presence of a solvent, the contribution of the degrees of freedom of each reaction component in the solution is considered to be quite large, and the reaction product with a low crosslink density is considered as a solution product. In view of the fact that they remain in the product, the incorporation of low-molecular-weight reaction products into the product is avoided, and thus has the effect of reducing gas generation during the firing of the product. One of the features of this graft reaction is that when the instinct is carried out in a solution, the product becomes finely divided by stirring during cooling as well as during the reaction, so that pulverization and pulverization are not required. The stirring conditions depend on the shape of the reactor and the shape of the stirring device, but are generally 300 to 1500 rpm.

The aromatic raw material, the catalyst and the cross-linking agent are appropriately combined and reacted according to the purpose, and the obtained graft product is separated and dried from a solvent to obtain a powdery molding raw material. In addition to filtration, spray drying,
Any means such as freeze drying may be used. The obtained molding raw material has high fluidity and moldability, and can be molded into an arbitrary shape by molding or (CIP (cold isostatic press) in this state. In addition, the molding material of the present invention is thermosetting. Because of having the usual thermosetting molding and HIP (hot iso
Static press) is also possible.

When the aggregate has a certain shape such as a felt shape, a graft reaction product can be easily obtained by impregnating and impregnating the aggregate with a reactive component, and reacting after drying. By firing, a desired molded product is obtained.

Next, the present invention will be described more specifically with reference to examples.

Example 1 10 parts by weight of commercially available natural graphite pulverized to an average particle size of 0.5 μm was dispersed as an aggregate in 300 parts by weight of O-xylene. A coal tar pitch 5 having a softening point of 60 ° C. is added to this mixture.
After adding 4.6 parts by weight of P-xylene glycol and heating to 120 ° C., a solution prepared by dissolving 0.5 parts by weight of P-toluenesulfonic acid in methanol was gradually added, and the mixture was stirred with a magnetic stirrer at 500 rpm for 30 minutes. Allowed to react for minutes. Next, 5 parts by weight of phenol and 8.5 parts by weight of benzaldehyde were added while maintaining the mixture at 120 ° C., and a solution obtained by dissolving 0.01 part by weight of P-toluenesulfonic acid in methanol was gradually added and stirred for 20 minutes. Reacted.

The reaction product was cooled, filtered, and the solid content was washed with n-hexane. After drying, a molding raw material was obtained. This molding material had an average particle size of 70 μm and exhibited good fluidity. The forming raw material was mold press at a molding pressure of 1000kg / cm ^2, 50φ, 10mm
A molded product of t was obtained.

After heat-softening the molded body at 200 ° C for 1 hour, it is fired in an inert atmosphere up to 1000 ° C at a heating rate of 50 ° C / hr.
The temperature was raised to 2800 ° C. at a temperature rising rate of 00 ° C./hr to graphitize.

This graphitized sample had a bending strength of 950 kg / cm ^{2 and} a coefficient of thermal expansion of 3.0 × 10 ⁻⁶ / ° C.

Comparative Example 1 Using the same aggregate and solvent as in Example 1, 10 parts by weight of coal tar pitch having a softening point of 60 ° C. was added, followed by stirring at 120 ° C. for 30 minutes, followed by cooling. And washed. The resulting solid was lumpy. Example 1
Molded in the same manner as above and heat-treated at 200 ° C for 1 hour.
Foaming was shown and subsequent steps were not possible.

Example 2 A softening point of 90 using 300 parts by weight of methylnaphthalene as a solvent.
10 parts by weight of coal tar pitch at ℃ and 6.9 parts by weight of P-xylylene glycol were dissolved at 120 ° C. while stirring.
This solution was impregnated in advance with a 5% by weight methanol solution of P-toluenesulfonic acid, dried at 50 ° C, and immersed in 20 parts by weight of a carbon fiber felt having a bulk specific gravity of 0.25, and reacted at 120 ° C for 1 hour. Continue adding resorcinol to the reaction solution.
10 parts by weight of terephthalaldehyde was added, 12 parts by weight of terephthalaldehyde was added, and after stirring, a solution of 0.01 part by weight of P-toluenesulfonic acid dissolved in methanol was gradually added and reacted at 120 ° C. for 30 minutes. After cooling, the felt was taken out, washed sufficiently with n-hexane, and dried under reduced pressure. The dried felt was thermoset molded at a molding pressure of 200 ° C. and 150 kg / cm ² . The molded body was heated to 2000 ° C. at a rate of 50 ° C./hr in an inert atmosphere. After firing, when the bending strength of the molded body was measured, 12
The value was 00 kg / cm ² .

Example 3 20 parts by weight of petroleum calcine coke having an average particle size of 20 μm was dispersed in 300 parts by weight of tetralin. After adding 5 parts by weight of coal tar pitch having a softening point of 65 ° C. and 4.7 parts by weight of dimethyl-P-xylene glycol to this mixture and heating to 120 ° C., a solution obtained by dissolving 0.6 part by weight of P-toluenesulfonic acid in methanol was added. The reaction was gradually added, and the reaction was carried out for 60 minutes while stirring at 800 rpm using a magnetic stirrer. Subsequently, 5 parts by weight of resorcinol and 6 parts by weight of benzaldehyde were added to this solution, and then 0.005 parts by weight of P
-A solution prepared by dissolving toluenesulfonic acid in methanol was gradually added, and the mixture was reacted with stirring for 20 minutes. The reaction product was graphitized by the same treatment as in Example 1. The sample after graphitization was heated rapidly to 2100 ° C. in 5 seconds using a high-frequency induction furnace with a high-frequency induction furnace for measuring thermal shock resistance in 5 seconds, but no change was observed. Processed to the same dimensions for comparison. Graphite material (trade name T-
6) was processed into the same dimensions and subjected to the same heating.

(Effect) Since the carbon-graphite material obtained in the present invention is a thermosetting resin obtained by reacting a cross-linking agent with an aromatic raw material as a binder layer, not only is it difficult for deformation to occur during firing, but also
Depending on the selection of the aromatic raw material and the cross-linking agent, those having various properties can be obtained.In addition, since the graft reaction product undergoes molecular weight fractionation by the solvent, the gas generated during calcination can be reduced and the carbonization yield can be improved. Further, since the forming raw material obtained by drying is a powder having high fluidity that can be formed as described above, a pulverizing step is not required unlike the conventional method, and the forming raw material is formed by laminating different binders. In this case, it exhibits characteristics that cannot be obtained in the past. Particularly, in the case of firing graphite, the rate of temperature rise can be increased without generating cracks, so that the number of production days can be greatly reduced.

The carbon / graphite material obtained by the method of the present invention has small falling particles and is hard to damage the mating material, a low-consumption electrode for finishing electric work, a jig with high machining accuracy, and a material for precision machining. Further, it is used as a thermal shock material having a low coefficient of thermal expansion.

Claims (2)

(57) [Claims] 1. A carbonaceous aggregate, an aromatic raw material,
After mixing and stirring the catalyst and the cross-linking agent to form a uniform dispersion, the mixture is heated to graft polymerize an aromatic material on the surface of the carbonaceous aggregate, and the obtained reaction product is again used as the aromatic material. Graft polymerization by reacting with different aromatic raw materials, catalysts and cross-linking agents, separating and drying the obtained reaction product from a solvent to obtain a powdery molding raw material, molding the raw material, and firing. Manufacturing method of carbon and graphite materials. 2. An aromatic raw material, a catalyst and a cross-linking agent are added to a solvent and stirred to form a uniform solution. A molded body made of carbonaceous aggregate is immersed and impregnated in the solution, and then heated to reduce the carbon content. The aromatic raw material is graft-polymerized on the surface of the aggregate, and the obtained molded body is reacted again with an aromatic raw material, a catalyst and a cross-linking agent different from the aromatic raw material, and graft-polymerized. A method for producing a carbon / graphite material, comprising taking out, heating, pressing and firing.