JPH1059782A - Production of carbon formed body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a carbon formed body the mechanical working stage of which can be simplified and which has excellent dimensional accuracy and improved gas permeability in the direction along its laminated layers by impregnating plural carbonizable organic polymer fiber sheets (components (a)) with a material (component (b)) obtained through mixing of a drying oil or its fatty acid with a phenolic resin solution, laminating the impregnated sheets thus obtained, heating and pressing the resulting laminated sheets to form a laminate, subjecting the laminate to blanking to form a laminate blank and subjecting the laminate blank to heat treatment in a non-oxidizing atmosphere. SOLUTION: In this production of a carbon formed body, as the components (a), sheets formed by using cellulosic rayon fiber or lignin fiber, each of which requires no treatment for providing it with infusibility, as the major constituent of a raw material of the sheet, are preferred on account of the cost and workability and e.g. sheets of commercially available linter paper or kraft paper can be used. Further, according to applications of the carbon formed body, sheets formed by papermaking a raw material contg. a carbon powder, ceramic powder or metal powder, can also be used. As the component (b), a material obtained by mixing a drying oil or its fatty acid with a phenolic resin solution in an amount equivalent to 1 to 50wt.% of the weight of the phenolic resin solution, (e.g. tung oilmodified phenolic resin solution) is used. The plural impregnated sheets are laminated and, thereafter, the laminated sheets are heated and pressed at 130 to 200 deg.C under a 5 to 50kg/cm<2> pressure for 5 to 60min. The heat treatment temp. of the laminate blank is preferably 800 to 2,800 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 carbon material. More specifically, the present invention relates to a method for manufacturing a carbon material. And a method for producing a shaped carbon article.

[0002]

2. Description of the Related Art Carbon materials have long been used in many fields by utilizing their excellent chemical resistance, heat resistance, slidability, electrical conductivity, thermal conductivity and the like. In recent years, it has become an indispensable material for sliding materials, semiconductors, liquid crystals, optical fibers, fuel cells, heat dissipation, and the like. In general, these carbon materials are usually cut out of a bulk material / material and machined for use.

[0003]

On the other hand, recently, a sheet obtained by mixing an organic fiber, a pulp, or the like with a fuel cell substrate or the like is impregnated with an organic polymer substance such as a thermosetting resin and carbonized by heating. There has been proposed a method for producing
9-144625, JP-A-5-254957). These methods can produce a carbon plate having a uniform thickness, but the outer shape needs to be machined after carbonization. Also, a method has been proposed in which a cellulose fiber containing a drying oil and a phenol resin are mixed, filled into a mold or the like to form a green molded plate, and then calcined and carbonized (JP-A-1-320208). However, in this method, filling and unloading the mold, pressurization for a certain time in the mold,
There is a problem that the molding speed is slow because heating is required.
In view of the above points, the inventors simplified the machining process,
A method for producing a carbon shaped body having a predetermined shape was found.

[0004]

According to the present invention, there is provided a method of manufacturing a carbon shaped article, comprising impregnating a carbonizable organic polymer fiber sheet with a phenol resin solution containing a drying oil or a fatty acid thereof, and laminating the impregnated sheet. And heating and pressing to form a laminate, punching the laminate into a predetermined shape, and firing the laminate at 800 ° C. or higher in a non-oxidizing atmosphere.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Carbonizable organic polymer fiber sheets are made of organic fibers commonly used in the production of carbon fibers, such as rayon, pitch fibers, lignin fibers, phenol resin fibers, and acrylic fibers. Any of these sheets can be used, but from the viewpoint of cost and workability, it is preferable to use a cellulosic rayon fiber or lignin fiber as a main raw material which does not require infusibilizing treatment. For example, commercially available linter paper, fluff paper, or the like can be used. Further, a sheet obtained by mixing and forming carbon powder, short carbon fiber, ceramic powder, and metal powder can also be used depending on the application. Carbon powder,
If short carbon fibers are mixed and made into paper, the electrical conductivity and thermal conductivity of the carbon shaped body can be improved, and the contraction rate of the carbon shaped body during carbonization can be reduced.

[0006] It is also possible to improve sliding characteristics by mixing paper with lead powder. Further, if the ceramic powder is mixed and made into paper, the oxidation resistance of the carbon shaped body can be improved. The mixing amount of carbon powder, short carbon fiber, metal powder, and ceramic powder in the mixed papermaking sheet is 50 with respect to the sheet weight.
If it exceeds 50%, cracks, chips and the like are generated in the laminated board in the subsequent punching step, so that it is preferably less than 50%. A phenol resin solution is an important factor in the present invention, and ordinary phenol resins are not suitable for the purpose of the present invention. When a normal phenol resin is used, cracks, chips, etc. are generated at the time of punching.

Therefore, the phenol resin solution in the present invention needs to use a mixture of a phenol resin and a drying oil or its fatty acid. The mixing amount of the drying oil or its fatty acid is preferably 1 to 50% by weight based on the phenol resin.
If the content is less than 1%, the punching workability of the laminate is poor, and cracks, chips and the like are likely to occur. If it is 50% or more, the carbonization rate at the time of carbonization and firing decreases, the function as a binder decreases, and the physical properties of the product decrease. As the drying oil or its fatty acid, for example, tung oil, linseed oil, dehydrated castor oil, soybean oil, cashew nut oil, or its fatty acid can be used. The phenol resin solution is impregnated into the sheet at a resin solid content of 30% by weight.
60% is preferred. When the amount of the phenol resin solution impregnated in the sheet is 30% or less in terms of the resin solid content, the amount of the binder in the product is reduced, and delamination during lamination and compression is likely to occur. When the resin solid content of the impregnated amount is 60% or more, the escape of the pyrolysis gas generated during the carbonization firing to the outside of the system becomes poor, and carbonization firing defects such as cracks and blisters tend to occur.

In the step of impregnating the sheet with the phenol resin solution, the above-mentioned carbon powder, short carbon fiber, ceramic powder and metal powder are mixed and impregnated with the phenol resin solution to obtain a sheet similar to the mixed papermaking sheet. Properties can be improved. The mixing amount of the carbon powder, the short carbon fiber, the ceramic powder, and the metal powder in the impregnation step is preferably less than 50% for the same reason as the mixing amount of the mixed papermaking sheet. The sheet impregnated with the phenolic resin solution
130-200 after stacking multiple sheets in consideration of product thickness
Hot pressed at a temperature of ° C. When considering productivity,
It is preferable that the impregnated sheet is dried in advance at about 100 to 150 ° C. for several minutes and then heated and pressed. If the hot pressing temperature is too high, the laminated plate after pressing is hard and brittle, and it is difficult to perform punching. Therefore, the hot pressing temperature is preferably 200 ° C. or lower.

The lower limit of the heating press temperature varies depending on the production conditions of the mixed papermaking sheet, for example, the mixing amount of carbon powder, metal powder and the like.
It is preferable to secure 30 ° C. or higher. The pressure of the heating press is preferably 50 kg / cm ² or less because too high a pressure makes the laminate hard and brittle. On the other hand, if the pressure is too low, the laminate will peel off, so that the pressure is preferably 5 kg / cm ² or more. If the heating and pressurizing time of the heating press is too long, the laminate is likely to be hard and brittle, so that it is preferably 60 minutes or less. On the other hand, if the length is too short, the laminate will be peeled off or unadhered. Therefore, it is preferable to secure at least 5 minutes or more.

Although the punching process is not particularly limited, any of a processing machine used for a printed wiring, a punching process of a paper-baked laminated board, and the like can be used. The laminate is punched by sandwiching the laminate between the molds having the desired product shape and applying impact pressure. The punching workability can also be adjusted during this punching process. Heating the mold and heating the laminate will produce a little stickiness, which helps to prevent cracking and cracking during punching. It is also possible to heat the mold as needed. After punching, the punched laminate is sandwiched between graphite plates,
Alternatively, it is buried in packing coke and fired in a non-oxidizing atmosphere according to a conventional method. If the firing temperature is lower than 800 ° C, carbonization is insufficient, and the firing temperature is preferably 800 ° C or higher. If the rate of temperature rise is too high, deformation or foaming of the carbon shaped body is likely to occur, so the temperature is preferably 50 ° C./hr or less. Incidentally, graphitization treatment can be performed if necessary. However, according to the results of the study by the present inventor, at a treatment temperature of 2800 ° C. or more, delamination tends to occur in the carbon shaped body, so the upper limit of the treatment temperature is 2800 ° C.
It is preferable to set the degree. For graphitization, general high-temperature heating furnaces such as a vacuum furnace, a gas replacement furnace, a high-frequency heating furnace, a heater heating furnace, and an Acheson furnace can be used.

[0011]

Embodiments of the present invention will be described below. Example 1 Commercially available base paper for laminated board (Koji Paper, manufactured by Oji Paper Co., Ltd., S-10) was immersed in tung oil-modified phenolic resin (Resin D, manufactured by Showa Polymer Co., Ltd.) and then at 110 ° C. for 1 minute. Dry to make an impregnated sheet. The resin solid content in the impregnated sheet was 40%, and the volatile content was 9% (at 160 ° C. for 30 minutes,
The weight change before and after drying was measured and calculated based on the base paper weight). The impregnated sheets were laminated under the following conditions and heated and pressed to produce a laminated plate. Lamination Method Thirty sheets were laminated to form a laminate having a thickness of 3.5 mm under the conditions of 10 kg / cm ² , 140 ° C., and 30 minutes.

Example 2 Commercially available base paper for laminated board (kraft paper, S-10, manufactured by Oji Paper Co., Ltd.) was converted to carbon powder (UFG-30, manufactured by Showa Denko KK, average particle size = 10 μm). The resin was immersed in a tung oil-modified phenol resin (Resin D, manufactured by Showa Polymer Co., Ltd.) mixed with 20% by weight and dried at 110 ° C. for 1 minute to prepare an impregnated sheet. The resin solid content in the impregnated sheet is 4
The content was 8% and the volatile content was 9% (at 160 ° C. for 30 minutes, the weight change before and after drying was measured and calculated based on the base paper weight). The impregnated sheets were laminated under the following conditions and heated and pressed to produce a laminated plate. Lamination Method Thirty sheets were laminated to form a laminate having a thickness of 4.5 mm under the conditions of 8 kg / cm ² , 140 ° C., and 20 minutes.

Example 3 Rayon fiber (2 denier ×
8mm) 30% by weight, Canadian freeness 650m
Wood pulp (NBKP: Crofton) 40 beaten to l
% By weight, alumina powder (manufactured by Showa Denko KK, average particle size = 1
5 μm) 20% by weight, binder fiber (Kuraray Co., Ltd.)
(VBP105, 1 denier x 4 mm), 10% by weight, and a slurry diluted with water were mixed at a papermaking speed of 30 m / min using a short net inclined wire machine to prepare a mixed papermaking sheet. The obtained sheet was a uniform sheet having a basis weight of 80 g / m ² and a thickness of 0.4 mm with good texture. This mixed papermaking sheet was immersed in a tung oil-modified phenolic resin (Resin D, manufactured by Showa Polymer Co., Ltd.) and dried at 110 ° C. for 1 minute to prepare an impregnated sheet. The resin solid content in the impregnated sheet is 40
% And volatile content were 9% (at 160 ° C. for 30 minutes, the weight change before and after drying was measured and calculated based on the base paper weight).
The impregnated sheets were laminated under the following conditions and heated and pressed to produce a laminated plate. Lamination Method Thirty sheets were laminated to form a laminate having a thickness of 5.1 mm under the conditions of 10 kg / cm ² , 140 ° C. and 30 minutes.

Example 4 A sheet prepared in the same manner as in Example 3 was treated with carbon powder (UFG- manufactured by Showa Denko KK).
30, tung oil-modified phenolic resin (Resin D, manufactured by Showa Polymer Co., Ltd.) mixed with 20% by weight of an average particle size of 10 μm.
And then dried at 110 ° C. for 1 minute to produce an impregnated sheet.
The resin solid content in the impregnated sheet was 48%, and the volatile content was 9% (calculated based on the weight of the base paper by measuring the change in weight before and after drying at 160 ° C. for 30 minutes). The impregnated sheets were laminated under the following conditions and heated and pressed to produce a laminated plate. Lamination Method Thirty sheets were laminated to form a laminate having a thickness of 6.0 mm under the conditions of 10 kg / cm ² , 140 ° C. and 30 minutes.

The laminated plate of each of Examples 1 to 6 has an outer diameter of 30 ± 0.
Using a punching die having a diameter of 05 mmφ and an inner diameter of 5 ± 0.05 mmφ, punching was performed at a set temperature (die temperature) of 150 ° C. with a punching machine manufactured by Amada Co., Ltd. The punched laminate has no cracks, cracks, chips, etc.
It was within the range of ± 0.05 mmφ and inner diameter of 5 ± 0.05 mmφ. Each of the punched laminated plates of Examples 1 to 4 was buried in packing coke and placed in a stainless steel sagar, and was heated at a rate of 10 ° C./hr in a N ₂ gas atmosphere at 100 ° C.
Treated to 0 ° C.

(Example 5) The carbon shaped body of Example 1 treated at 1000 ° C was further subjected to an Acheson furnace at 300 ° C /
It was graphitized at 2500 ° C. at a heating rate of hr.

Example 6 The carbon shaped body of Example 2 treated at 1000 ° C. was further subjected to 300 ° C./300° C. in an Acheson furnace.
It was graphitized at 2500 ° C. at a heating rate of hr.

The appearance of each of the carbon shaped articles of Examples 1 to 6 was good. Table 1 shows the dimensional accuracy of the carbon shaped body. Although there is a difference in the amount of shrinkage due to sheet characteristics between the examples, the dimensional tolerance of the inner and outer diameters in each example is ± 0.1 mm.
It showed good dimensional accuracy. In addition, the carbon shaped article according to the present invention has a gas permeability in the sheet lamination layerwise direction which is one to two orders of magnitude higher than that in the translucent direction, and the gaseous permeability is better in the layered direction than in the translucent direction. That is, the pyrolysis gas also easily escapes in the direction of the stratum, the gas escape during firing carbonization is improved, and the occurrence of defects such as foaming, cracks and cracks is reduced.
Table 2 shows the gas permeability values in the along-layer direction.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

As described above, according to the method for manufacturing a carbon shaped body according to the present invention, the machining process of the carbon body is greatly simplified by enabling punching into a predetermined shape in advance, and the size is reduced. It is possible to produce a carbon shaped body having excellent accuracy. Further, gas permeability in the direction of the stratum is improved.

Claims (3)

[Claims] 1. A carbonizable organic polymer fiber sheet is impregnated with a phenol resin solution in which a drying oil or its fatty acid is mixed, and the impregnated sheets are laminated and heated and pressed to form a laminate. A method for producing a carbon shaped body, comprising: punching into a non-oxidizing atmosphere and firing at 800 ° C. or more in a non-oxidizing atmosphere. 2. The carbon according to claim 1, wherein the carbonizable organic polymer fiber sheet is a mixed sheet of carbonizable organic polymer fiber and at least one of carbon powder, short carbon fiber, ceramic powder, and metal powder. A method for producing a shaped body. 3. The method for producing a carbon shaped body according to claim 1, wherein the phenol resin solution in which the drying oil or the fatty acid is mixed contains at least one of carbon powder, short carbon fiber, ceramic powder, and metal powder.