JPH01320279A - Production of porous carbonaceous material - Google Patents

Abstract

PURPOSE:To obtain porous carbonaceous material having high performance at low cost by a simple method wherein an inexpensive raw material such as paper is utilized by laminating specified paper and impregnating this paper with a thermosetting resin soln., heating and curing it and thereafter calcining the paper to perform carbonization treatment. CONSTITUTION:Firstly paper having properties of 50-150mum mean pore diameter and >=50% porosity is laminated at prescribed thickness. Then this laminated paper is impregnated with a thermosetting resin soln. having >=40% actual carbon ratio, heated and cured and thereafter calcined at >=1,000 deg.C in the nonoxidative atmosphere to perform carbonization treatment and thereby the aimed porous carbonaceous material is obtained. As the used paper, paper having properties of 50-150mum mean pore diameter and >=50% porosity is selected and utilized from paper or paper board produced by paper making pulp such as general domestic tissue paper on the market, various kinds of paper and base paper for corrugated board. The soln. of thermosetting resin is obtained by dissolving resin in an organic solvent such as alcohol and acetone in normal service and the concn. of the soln. is preferably set to 10-40wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a porous carbon material having both a high pore structure and strength characteristics.

[Prior Art] A typical method for manufacturing porous carbon materials is to knead coke powder with uniform particle size with a binder such as tar pitch, then crush, mold, and sinter. This method has the disadvantage of poor mass productivity because it is difficult to set conditions for obtaining a homogeneous and stable porous structure.

Additionally, a method for manufacturing porous carbon plates using carbon fiber skeletons has also been developed. In this method, organic fibers for manufacturing carbon fibers and valves, or raw materials made by blending these with carbonaceous powder, are made into a sheet, and then an organic polymeric substance or a solution of an organic polymeric substance in which carbonaceous powder is suspended is added to the sheet. It is impregnated and then fired, and is said to be suitable for electrode materials used in secondary batteries (Japanese Unexamined Patent Publications No. 61-236664 and No. 61-236665).

[Problems to be Solved by the Invention] However, in the above method, the organic fiber used as a raw material for manufacturing carbon fiber is expensive and requires a complicated paper-making process, so the product cost rises. .

The present invention provides a method for producing a high-performance porous carbon material at low cost through a simple process using inexpensive paper raw materials.

[Means for Solving the Problems] That is, the method for producing a porous carbon material according to the present invention involves laminating papers to a predetermined thickness, each having an average pore diameter of 50 to 150 μm and a porosity of 50% or more. The structural feature is that the material is impregnated with a thermosetting resin solution having a residual carbon content of 40% or more and cured by heating, and then subjected to firing carbonization treatment in a temperature range of 1000° C. or more in a non-oxidizing atmosphere.

The raw materials of the present invention are generally commercially available home-use bookworms,
Among paperboards or paperboards manufactured from paper valves such as mixed paper and cardboard base paper, those having properties of an average pore diameter of 50 to 150 μm and a porosity of 50% or more are selected and used. The average pore diameter and porosity of the raw paper are each 50 μm15
If it is less than 0%, pore clogging will be induced in the post-process from impregnation with thermosetting resin solution to calcination carbonization treatment, and on the other hand, if the average pore diameter exceeds 150 μm, the strength properties will deteriorate significantly. .

The raw paper is laminated to a predetermined thickness, compressed if necessary, and then impregnated with a thermosetting resin solution by dipping, coating, spraying, or other means.

At this time, wetting of the raw paper with the resin solution can be effectively improved by heat-treating the raw paper at a temperature range of approximately 50 to 200°C before lamination to remove moisture and modify the surface. .

The thermosetting resin used for impregnation must have a residual carbon content of 40% or more. The residual carbon content refers to the weight percent of carbon remaining when the resin is fired at 1000°C in a non-oxidizing atmosphere, and if this is less than 40%, the strength of the resulting porous carbon material will be reduced to a practical level. It becomes extremely difficult to improve. Examples of such thermosetting resins having a residual carbon content of 40% or more include phenol formaldehyde, furfuryl alcohol, and divinylbenzene, all of which can be effectively used for this purpose.

The thermosetting resin is converted into a solution by dissolving the resin in a commonly used organic solvent such as alcohol or amethane, and the concentration of the solution is preferably 10 to 40% by weight. The reason for this is that if the solution concentration is less than 10% by weight, the strength properties will deteriorate, and if it exceeds 40% by weight, smooth impregnation will be inhibited and pores will be blocked.

The impregnation is then heat cured. The preferred conditions for the heat curing treatment are to perform preliminary curing at a temperature of about 80° C. for about 10 hours, and then to raise the temperature to 180 to 300° C. for complete curing.

It is also possible to adjust the structural properties of the porous carbon material, such as its density and porosity, by impregnating it with a thermosetting resin solution again at the preliminary curing stage or by repeating this operation.

The material after heating and hardening is transferred to a firing furnace and subjected to firing carbonization treatment at a temperature of 1000° C. or more in a non-oxidizing atmosphere such as nitrogen, argon, carbon dioxide, etc. to obtain a porous carbon material.

[For production]

According to the present invention, paper having an average pore diameter of 50 to 150 μm5 and a porosity of 50% or more is used as a raw material base material, and the raw material is impregnated with a thermosetting resin solution having a residual carbon content of 40% or more. The unique pore structure of the base material and the binder-like function of the carbon produced from the thermosetting resin solution work synergistically to create a highly strong porous carbon structure with evenly distributed fine air-permeable pores. Realize the configuration of

Moreover, when the concentration of the thermosetting resin solution is set to 10 to 40% by weight, the above-mentioned effect is further promoted, and a high-performance porous carbon material can be obtained.

〔Example〕

Hereinafter, the present invention will be explained while comparing Examples and Comparative Examples.

Examples 1 to 3, Comparative Examples 1 to 3 Hybrid papers (calligraphy papers) having different average pore diameters and porosity were placed in an electric dryer and heat-treated at a temperature of 100°C for 12 hours. After 40 sheets of treated raw paper were laminated in close contact (thickness approximately 4M), phenol formaldehyde resin with a residual carbon content of 45% [manufactured by Sumitomo Durez ■, ゛Sumilite Resin P] was applied.
The raw paper was immersed in a 20% by weight ethanol solution of R940°' to sufficiently impregnate the resin solution into the raw paper structure.

The impregnation was pre-cured by holding at a temperature of 80°C for 10 hours.
Again, the thermosetting resin solution was immersed and precured in the same manner. Subsequently, the temperature was increased to 180° C., and heat treatment was performed for 1 hour to completely cure the impregnated resin.

Next, the hardened material is transferred to a firing furnace and heated under a nitrogen atmosphere.
It is fired and carbonized at a temperature of 1400°C to a thickness of about 2.
A porous carbon plate No. 5- was obtained.

Various physical properties of each porous carbon plate thus obtained were measured and shown in Table 1 in comparison with the average pore diameter and porosity of the raw material paper used.

In addition, the measurements of each characteristic were as follows: Average pore diameter and porosity were measured using mercury intrusion method, and bending strength and bending modulus were measured using JIS K691.
1. The apparent specific gravity and specific resistance were determined according to the method of JIS R7202.

Note that the characteristics of a conventional porous carbon material using organic fiber for carbon fiber as a raw material are also listed in Table 1 (Conventional example).

All of the examples of the present invention exhibited properties equivalent to or better than those of the conventional examples in terms of strength, pore structure, and specific resistance. The performance was significantly inferior.

Examples 4 to 6, Comparative Examples 4 to 6, mixed paper (calligraphy paper) with an average pore diameter of 60 μm and a porosity of 60% was used as the raw material paper, and after heat treatment and Mi layering in the same manner as in Examples 1 to 3, residual carbon was removed. The paper was immersed in ethanol solutions of phenol formaldehyde resin with different ratios and concentrations to sufficiently impregnate the resin solution into the raw paper tissue.

Next, the impregnated material was pre-cured, re-impregnated, heated and carbonized under the same conditions as in Examples 1 to 3 to produce a porous carbon material.

The physical properties of each porous carbon material thus obtained were measured and shown in Table 2 in comparison with the residual carbon percentage and melt 111i4 degree of the resin solution used.

From the results in Table 2, Comparative Example 4 in which the residual carbon percentage of the thermosetting resin was less than 40% had particularly low strength characteristics compared to the Examples of the present invention.

Further, even when the residual carbon percentage is 40% or more, in Comparative Examples 5 and 6 in which the resin solution concentration is outside of 10 to 40% by weight, the strength or pore structure is slightly reduced. Two were recognized.

(Effects of the Invention) As described above, according to the present invention, a porous carbon material having both a high pore structure and strength characteristics can be manufactured using an inexpensive raw material base material and a simple manufacturing process. It becomes possible to provide materials such as high-temperature insulation structural materials and electrode materials for secondary batteries at low cost.

Patent applicant: Tokai Carbon Co., Ltd.

Claims (1)

[Claims] 1. Paper having average pore diameter of 50 to 150 μm and porosity of 50% or more is laminated to a predetermined thickness.
A method for producing a porous carbon material, which comprises impregnating the porous carbon material with a thermosetting resin solution of 0% or more, heat-curing it, and then subjecting it to firing carbonization treatment in a temperature range of 1000° C. or more in a non-oxidizing atmosphere. 2. The concentration of the thermosetting resin solution with a residual carbon content of 40% or more is 10
The method for producing a porous carbon material according to claim 1, wherein the content is set to 40% by weight.