JPS6044963A - Manufacture of porous carbon plate - Google Patents

Abstract

PURPOSE:To provide a porous carbon plate having large porosity, high mechanical strength, and uniform quality by stacking a prepreg obtained by impregnating resin in a carbon fiber sheet, pressing, curing by heat, and carbonizing it. CONSTITUTION:30-70wt% of resin such as phenol resin is impregnated in carbon paper or carbon cloth. Several sheets of prepregs obtained are stacked so as to form desired thickness. This stack is heat-pressed in a suitable condition to cure resin, then it is heated in an atmosphere of inactive gas to carbonize resin. By this process, a porous carbon plate having good mechanical strength, porosity, and electric resistance is obtained. This plate is suitable for an electrode substrate for fuel cell.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for manufacturing a porous carbon plate such as an electrode substrate used in, for example, a fuel cell.

[Prior art and its problems]

Conventionally, methods for manufacturing porous carbon plates include mixing coke lumps with a combined form of raw material coke lump petroleum or coal pitch, shaping the mixture using an extruder, etc., and then heating and carbonizing it to form pores; Alternatively, a method is known in which carbon fibers are formed into a mat or paper shape using a suitable binding material and then heated and carbonized to form pores.

However, in extrusion molding using the former method, the pore size and porosity vary depending on the particle size of the raw material coke and the amount of binder, and in order to facilitate extrusion molding, the density of the mixture is increased and the molded product is It is difficult to provide larger porosity in order to obtain a high yield of . On the other hand, with the latter method, it is difficult to uniformly disperse the carbon fibers, making it impossible to obtain particularly large-area or thick-walled molded products, and the mechanical strength of the porous carbon plates obtained with both methods is It has the disadvantage of being low.

[Purpose of the invention]

The purpose of the present invention is to have large porosity, high mechanical strength,
Moreover, it is an object of the present invention to provide a method for manufacturing a homogeneous porous carbon plate. 7 [Summary of the Invention] The present invention provides carbon paper or carbon paper 1:+
By stacking sheets of prepurecra impregnated with phenol resin to the required thickness, pressurizing and heating them to harden the resin, and then carbonizing them, a porous carbon plate is obtained.

[Example of bending]

The present invention will be explained below based on examples.

Example 1 Carbon paper m having a thickness of 0.26XI and a basis weight of 357I.

is impregnated with a 10% methanol solution of phenol resin. This carbon paper is left in the atmosphere and completely volatilized in the methanol solution at room temperature, so that the content of Briprezin becomes 20 to 70% by weight.

゛order Vζ These prepregs are prepared for each resin content,
Stack the required number of sheets to obtain the specified thickness -1
The resin is cured by pressurizing and heating under conditions of 00 to 150°C and 160±5°C to form a carbon paper laminate. Furthermore, the carbon laminate with the resin completely cured is heated for 4 hours in a non-containing gas atmosphere such as nitrogen.
The resin is heated to a temperature of 00°C or higher to carbonize it to a thickness of 3cm.
A square porous carbon plate with each side of 100U was manufactured. The properties of the obtained porous carbon plate are shown in Table 1.

The results in Table 1 and above show that in order to make the thickness 1r uniform, the pressing force should be adjusted low for those with a small number of laminated sheets, and high for those with a large number of laminated sheets, but as can be seen from Table 1. For example, in a combination with a low resin content and a small number of laminated sheets, a porous carbon plate with an apparent density of 0.20 or less has poor adhesion between the prepregs, causing delamination 'a'. Therefore, in this example, it is found that the resin content is preferably 40% or more and the number of laminated sheets is 15 or more.

Next, in order to understand the variation in characteristics depending on the location of this laminate (lζ
, the resin amount was 40% and 00% by the same method as above.
using Gripreg, each 3 pieces thick and 30 pieces on each side.
Square porous carbon plates with a size of 0 cm were manufactured, and these plates were machined to cut out pieces measuring 100 ym x 1.00 m, and the characteristics of each porous carbon plate were investigated. This result is shown in Table 2, but for comparison, 1
The laminates with 0 sheets and additional sheets are shown.

From Table 2, it can be seen that when a large area is used, the variation in the characteristic 1'4' inside the porous carbon machine is relatively small, and the bending strength of the conventional porous carbon plate, which has an apparent density of 0.4, is 40. %? Therefore, in this example, about 1.5 times or more was obtained.Example 2 A plain weave carbon cloth with a thickness Q of 5 m and a basis weight of 180'/· was dried in a hot air drying oven at 100°C for 1 hour. After drying (7), this carbon cloth is impregnated with a 10% methanol solution of phenol resin at room temperature. The impregnated carbon cloth is air-dried at room temperature until methanol reaches a sufficient amount of tMf to form a prepreg. By repeating the above impregnation and air-drying operations, the resin content in the carbon cloth is i 10 , 2
0, 30, 40, 50, 60, 70 weight-1i
%Nobulipregl! ! I made 4 works. These prepregs
7 pieces + 1 for each gin content! ;Overlapping, 1[;o±5
The resin was compressed and hardened at 100° C. for 10 minutes, and molded using a mold so that a disc-shaped laminate with a thickness of 3 mm and a diameter of 100 mm was obtained. Furthermore, the laminated molded plate", (-100'
A porous carbon plate was obtained by heating and carbonizing for one day in a nitrogen gas atmosphere of carbon dioxide or higher. Table 3 of the obtained porous carbon plate Next, in the same manner as above, carbon cloth and resin were used, the resin haze of the Flipreg was fixed at 50%, and the number of laminated sheets of this Flipreg was -5, 6, 7, 8,9,10,12゜1=
4. From Tables 3 and 4, similar to the case of the carbon paper of Example 1, the same porous carbon was made by laminating and molding one sheet under the same method and conditions as above, then heating and carbonizing. When the upper right resin content is low, when J6 and the number of laminated sheets are small, the adhesion of the name rib L/g is poor and delamination occurs. (In this example, E is the product with the largest number of layers) ΔDue to the large amount of compression during molding, the impregnated resin is extruded from the cloth, resulting in a good molded product. I couldn't.

Example 3 A satin woven carbon cloth with a thickness of 9.9 m and a basis weight of 270'/,, = was used.':A Example 1. Resin impregnation treatment J! similar to Example 2! I! ? A prepreg FH with 1l-JJ color and 50% resin content was made. In this case, the thickness of the cloth is large, so the number of Flipreg layers is set to 3.4.
Three types of five sheets were formed, heated and carbonized under the same conditions as in Example 1.2, and were made of porous carbon 4fik with a thickness of 3 #4 and a diameter of 100 degrees Celsius. Table 5 VC shows the properties of these porous carbon plates. As can be seen from Table 5, in the case of Table 5, as in Example 1 and Example 2, when the laminated thickness of the flip-preg is less than the thickness of the porous carbon plate, the compressive force can be increased. Because of this, the resulting laminated molded plate produces delamination noise.

In addition, the measurement of porosity in Examples 1 to 3 above was carried out by JI
The porosity of SZ2506r sintered oil-impregnated alloy was measured according to Test Method J.

〔Effect of the invention〕

As explained in the examples above, the method for producing a porous carbon plate of the present invention uses carbon paper, cloak, or glue in which carbon fibers are uniformly dispersed.

Rosnato carbon sheet with phenol resin in total of 30~
By laminating and molding prepreg impregnated with 0% by weight of carbon fiber and then heating it to carbonize the resin, a porous carbon plate with a larger porosity and higher strength than conventional porous carbon plates can be obtained. According to the method of the present invention, the content of briflexurisin can be selected from a wide range depending on the type and porosity of the raw material (carbon sea), and the content will be greater than the thickness of the resulting laminate molded product. The number of sheets of prepreg (+- stacked & stacked and molded,
After that, the resin is carbonized and loses its function as an insulator, so a porous carbon plate with the necessary electrical conductivity is obtained.
do.

That is, the present invention is applicable to, for example, an electrode substrate/substrate used in a fuel cell.
If applied to C, strength, porosity, electrical resistance
This has the advantage that a porous carbon plate can be made according to the actual situation by taking into consideration not only the F4 property value but also the cost.

Claims (1)

[Claims] 1) Pile up a plurality of prepregs impregnated with 30 to 70% resin on a carbon fiber integrated sheet, heat and press this laminate to harden the resin, and then further heat to carbonize the resin. A method for manufacturing a porous carbon plate, characterized by: