JPH05194056A - Production of porous carbon plate having high compression resistance - Google Patents

Abstract

PURPOSE:To improve the compression resistance of a carbon plate by forming glassy carbon component skeletons in the carbon plate. CONSTITUTION:The production of a porous carbon plate improved in the compression resistance comprises impregnating a raw paper sheet produced from 40-90wt.% of polyacrylonitrile fibers and 60-10wt.% of pulp with an impregnation solution containing a phenolic resin and the powder of a phenolic resin insoluble in the impregnation solution so as to impregnate 100 pts.wt. of the sheet with 20-160 pts.wt. of the solid content of the soluble phenolic resin and with 1-50 pts.wt. of the solid content of the insoluble phenolic resin, drying the impregnated sheet, heating and oxidizing the dried sheet in air, thermally carbonizing the oxidized sheet at a temperature of >=800 deg.C in an inert atmosphere, and subsequently thermally treating the carbonized sheet at 2400-3000 deg.C in an inactive atmosphere.

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 porous carbon plate having high compression resistance. More specifically,
TECHNICAL FIELD The present invention relates to a method for producing a porous carbon plate having high compression resistance by firing a sheet obtained by a papermaking method from a slurry containing polyacrylonitrile fiber.

[0002]

2. Description of the Related Art Conventionally, in a method for producing a porous carbon plate, an impregnated sheet is prepared by impregnating a sheet made from a slurry containing organic fibers for producing carbon fiber and pulp with an organic polymer substance and carbonaceous powder. A method is known in which, after heating and pressurizing it to form a molded body, the molded body is heated at a temperature of 800 ° C. or higher in an inert atmosphere to carbonize it (Japanese Patent Publication No. 23505/1990). ..

According to this method, in the obtained carbon plate,
The thermal conductivity in the direction in which the fibers are arranged is large, but in the direction intersecting this direction, heat is transferred through the contact points, and the transfer distance becomes long, so the thermal conductivity is small. was there. In order to solve this problem of low thermal conductivity, the molded body should have a temperature of 2400 ° C to 300 ° C.
When heat-treated at 0 ° C., it is effective to impart tension to each other due to the difference in shrinkage ratio between polyacrylonitrile carbon and phenol resin carbon, thereby promoting graphitization. However, if graphitization proceeds too much, slippage of crystal planes easily occurs, and thus there is a problem that the compression strength of the obtained carbon plate decreases as the graphitization proceeds.

[0004]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a method for producing a porous carbon plate having excellent compression resistance in the plate thickness direction.

[0005]

According to the present invention, in producing a porous carbon plate, a polyacrylonitrile fiber-containing sheet to be carbonized is impregnated with a phenol resin solution containing an insoluble phenol resin powder dispersed therein. , Has succeeded in solving the above problems.

The method for producing a porous carbon plate having high compression resistance according to the present invention is a polyacrylonitrile fiber 40-90.
An impregnated sheet obtained by impregnating 100 to 100 parts by weight of the sheet with 20 to 160 parts by weight of a phenolic resin as a solid content, and impregnating a sheet obtained by making a slurry of 60% to 10% by weight of pulp with paper. When the impregnated sheet is dried, it is heated and oxidized in air, and further heated and carbonized at 800 ° C. or higher in an inert gas atmosphere to produce a porous carbon plate. Dispersing and containing a phenol resin powder that does not dissolve in a solution, and adhering 1 to 50 parts by weight of the insoluble phenol resin as a solid content to 100 parts by weight of the myogami sheet in the impregnating step. It is characterized by.

[0007]

The non-soluble phenol resin powder used in the present invention does not become graphitized and becomes glassy carbon even when heat-treated at 2400 ° C. or higher. Such a phenol resin powder is mixed and dispersed in a phenol resin solution. Then, an impregnating liquid is prepared and impregnated with the polyacrylonitrile fiber-containing sheet, so that the content of glassy carbon, which is resistant to compression, can be increased in the obtained carbon plate. As the insoluble phenol, resin powder that is almost insoluble in water and insoluble in solvents such as ethyl alcohol, methyl alcohol and acetone is used.

In the method of the present invention, the impregnating liquid contains a soluble phenol resin, an insoluble phenol resin powder and, if necessary, a carbonaceous powder in a weight ratio of 20 to 160: 1 to 50: 1.
.About.40. The base paper sheet is impregnated with this impregnating solution to obtain a solid content of 2 per 100 parts by weight of the base paper sheet.
0 to 160 parts by weight of soluble phenol resin, 1 to 50 parts by weight of solid content of insoluble phenol resin powder, and 1 to 40 parts by weight of carbonaceous powder are attached as necessary.

In the method of the present invention, after the impregnated sheets are dried, they may be molded alone or in a plurality of layers, and the mixture may be heated and pressed to simultaneously perform the molding and curing treatments.

The insoluble phenolic resin powder used in the present invention is one that does not dissolve in water or an organic solvent for an impregnating liquid, which will be described later, in an amount of 50% by weight or more at room temperature, and has a particle size of 40 μm or less. preferable. Its particle size is 40
If it is larger than μm, it becomes difficult to uniformly disperse the insoluble phenol resin powder in the impregnating liquid and uniformly impregnate the base paper sheet in the impregnation step. As powder particles,
Preferably, those having a particle size of 1 to 30 μm are used, for example, Univex C-10, C-30, UA-1.
0, and UA-30 (both are trademarks, made by Unitika),
And R-800 and S-830 (both are trademarks,
Kanebo) and the like can be used.

If the insoluble phenol resin powder is impregnated too much, the raw material cost will be increased, which is not preferable. Therefore, the impregnation amount of the insoluble phenol resin powder is 1 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the base paper sheet.

The cause of the high compressive strength of the carbon plate obtained by the method of the present invention is that when heat treated at high temperature, the polyacrylonitrile fiber and the phenol resin are graphitized, but the insoluble phenol resin powder is glassy carbon after heat treatment. Therefore, it is considered that the glassy carbon does not progress so much and the glassy carbon forms the amount and the skeleton of the carbon plate, and thus the obtained carbon plate exhibits high compression resistance.

In the method of the present invention, the polyacrylonitrile fiber has a thickness of 0.5 to 15 denier and a length of 0.
5 to 50 mm, preferably 0.5 to 50 mm in length from the viewpoint of papermaking property.
Select a 20 mm one according to the purpose and use it.

The pulp used in the present invention is not particularly limited in its type, and can be appropriately selected from the pulps generally used for papermaking. The beating degree is preferably in the range of Canadian Freeness 600 to 200 ml, and several kinds of pulp and beating degree may be mixed and used.

As the phenol resin solution used in the present invention, a solution containing at least one of liquid resole resin and novolac resin can be used. The liquid resol resin is classified into a completely water-soluble type, a partially water-soluble type, and a solvent solution type, but any one may be used. The novolac resin may be used together with a curing agent such as hexamine, but it may be used as a mixture with the resole resin without using the curing agent. When mixing resole resin and novolac resin, 40% resole resin in the mixture.
It is preferable that the above content is contained.

In the method of the present invention, when a carbonaceous powder is dispersed in the impregnating liquid, this carbonaceous powder is effective for improving the electric conductivity and thermal conductivity of the obtained carbon plate. As the carbonaceous powder, if the particle size is too large, the impregnating property is poor, and unevenness of impregnation occurs. Therefore, it is preferably 0.1 to 40 μm.
More preferably, graphite having a particle size of 0.5 to 10 μm, carbon black, or the like is used.

In the method of the present invention, the insoluble phenol resin powder is an aqueous solution of phenol resin, an aqueous emulsion,
Alternatively, it is mixed with an organic solvent solution and impregnated into a base paper sheet. If necessary, carbonaceous powder is simultaneously mixed and impregnated.
This impregnation method is not particularly limited, and may be any conventional method such as a dipping method, a spray method, a roll coating method, a brush coating method, or a doctor coating method. As the organic solvent used for the impregnation liquid, one kind selected from methyl alcohol, ethyl alcohol, acetone, isopropyl alcohol, n-butyl alcohol, ethylene glycol, acetic acid ester, or a mixed solution of two or more kinds is used. It

If the total impregnated amount of the phenolic resin attached to the base paper sheet is too small, the binder effect and the carbonization yield at the time of carbonization will be insufficient, and if it is too much, the sheet will be clogged. , It becomes brittle again. The total impregnation amount of the phenol resin is 20 to 160 parts by weight with respect to 100 parts by weight of the base paper sheet,
It is preferably 80 to 100 parts by weight.

When a carbonaceous powder is used, if its impregnation amount becomes excessive, it causes clogging, making it difficult to adjust the porosity. Therefore, the impregnated amount of carbonaceous powder is preferably 1 to 40 parts by weight, and more preferably 10 to 30 parts by weight, based on 100 parts by weight of the base paper sheet.

The sheet impregnated with the phenol resin-containing impregnating solution is generally subjected to a press molding process. This press molding is effective for imparting the necessary thickness, shape, porosity, and pore diameter to the final carbon plate, and at that time,
The combined use of heat treatment cures the phenol resin in the impregnated sheet. At this time, a thick carbon plate can be easily obtained by stacking a required number of impregnated sheets and pressing the same as above. Press heating condition is 15
0 to 220 ° C. and 1 to 60 minutes are suitable.

The press-treated sheet is subjected to a heat oxidation treatment, if necessary. This heat oxidation treatment
It is effective for improving the carbonization yield of the acrylonitrile fiber after the heating and firing step. The treatment conditions for the heat oxidation are not particularly limited, but the heat treatment is preferably performed in air at a temperature of 150 to 350 ° C. for several tens of minutes to 100 hours.

The above heat-oxidized sheet is carbonized by heating at a temperature of 800 to 1200 ° C. in an inert gas atmosphere, and then 2400 to 3000 ° C. in an inert gas atmosphere.
It is preferably heat-treated at 2700 to 3000 ° C., whereby the porous carbon plate of the present invention is obtained.

In order to impart high thermal conductivity and electrical conductivity to the carbon plate, it is effective to increase the production amount of graphite, but impregnation with an impregnating liquid containing a non-graphitizable resin such as phenol resin is used. It is necessary to heat-treat the obtained polyacrylonitrile fiber-containing sheet at a high temperature of 2400 ° C. or higher, preferably 2700 ° C. or higher. However, in general, high-temperature heat treatment at 3000 ° C. or higher is difficult in terms of equipment.

[0024]

The present invention will be further illustrated by the following examples, which are not intended to limit the scope of the present invention.

Example 1 20% by weight of wood parf (NBKP) beaten to a Canadian freeness of 250 ml and a thickness of 10 denier,
From a water slurry composed of 80% by weight of acrylonitrile fiber having a length of 3 mm, a basis weight of 100 was obtained by a conventional method using a cylinder paper machine.
A g / m ² base paper sheet was produced. Separately, a soluble phenolic resin (trade name: PL-2215 manufactured by Gunei Chemical Co., Ltd.),
Insoluble phenolic resin powder (Unitika, trademark: UA-
10, particle size 10 μm or less) and carbonaceous powder (particle size 10 μm
and m) were mixed in a weight ratio of 80:10:20 to prepare an impregnation liquid consisting of a methanol solution having a total solid content of 35%.
The base paper sheet was impregnated with the impregnating liquid so that the total solid content was 110.
Impregnation was performed so as to be g / m ² . The impregnated sheet is a solid, soluble phenolic resin 80 g / m ^2, insoluble phenol resin 10 g / m ^2, and carbonaceous powder 20 g /
m ² was included. The impregnated sheet was dried at a temperature of 105 ° C.

11 dried impregnated sheets were stacked, and this laminate was hot pressed at a temperature of 170 ° C. for 5 minutes. At that time, a spacer was used to form a press plate having a thickness of 3.9 mm. This press plate was heat-treated in air at 220 ° C. for 40 hours, then sandwiched between graphite plates, and heat-carbonized at 1000 ° C. for 1 hour in nitrogen gas, and then argon gas. In 2800 ℃, 30
The porous carbon plate was manufactured by performing heat treatment for 1 minute.

The compressive strength and JIS hardness of the above carbon plate were measured by the following methods. The compressive strength was measured by using a tensile tester (manufactured by Toyo Baldwin), and when the carbon plate was compressed at a rate of 0.4 mm / min with respect to an area of 2.5 cm ² , the buckling was started. The stress per cm ² was measured and is expressed by this measurement value. The JIS hardness was measured with a JIS hard nester (manufactured by Shimadzu Corporation). This value represents the strength against compression at one point of the carbon plate. The test results are shown in Table 1.

Example 2 A carbon plate was manufactured in the same manner as in Example 1. However, the impregnated amount of the insoluble phenol resin powder was 30 g / m ² and the thickness of the press plate was 4.2 mm. The test results are shown in Table 1.

Comparative Example A carbon plate was manufactured in the same manner as in Example 1. However, the insoluble phenol resin powder was not used, and the thickness of the press plate was 3.7 mm. The test results are shown in Table 1.

[0030]

[Table 1]

As is clear from Table 1, the carbon plates of Example 1 and Example 2 obtained according to the present invention were the same as Comparative Example 1
The compression strength in the thickness direction and the JIS hardness were remarkably improved as compared with the carbon plate of No. 2.

[0032]

Industrial Applicability According to the present invention, a sheet obtained from a polyacrylonitrile fiber and pulp by a papermaking method is impregnated with an impregnating solution containing a soluble phenol resin and an insoluble phenol resin powder, and the impregnated sheets are preferably laminated. This is a method of subjecting this impregnated sheet to heat-oxidation in air to carbonize it, and then further heat treatment to obtain a porous carbon plate having excellent compression resistance. According to the present invention, the impregnated insoluble phenol resin becomes glassy carbon by heat carbonization and heat treatment to form a skeleton that bears compressive stress, thereby significantly improving the compression resistance of the porous carbon plate.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location D01F 9/22 7199-3B 11/14 D21H 19/16 13/18

Claims (1)

[Claims] 1. A sheet obtained by making a slurry of polyacrylonitrile fiber of 40 to 90% by weight and pulp of 60 to 10% by weight, and a solid content of 20 to 160 per 100 parts by weight of the sheet. An impregnated sheet is prepared by impregnating parts by weight of a phenolic resin, and the impregnated sheet is dried, heated and oxidized in air, and further carbonized by heating at 800 ° C. or higher in an inert gas atmosphere to produce a porous carbon plate. In doing so, the phenol resin solution is dispersed and contained in the phenol resin solution, and in the impregnating step, the paper-made sheet has a solid content of 1 to 50 parts by weight per 100 parts by weight thereof. Part of the insoluble phenolic resin powder is attached to the porous carbon plate.