JPS60167271A - Manufacture of porous carbon electrode with rib - Google Patents

Abstract

PURPOSE:To produce a porous carbon electrode with rib for a fuel cell by impregnating an organic high molecular substance into a sheet manufactured by using a mixture of carbon fibers, pulp, and binder with a paper making machine, by heat-pressing, cutting, then carbonizing them. CONSTITUTION:A mixture of 60-95wt% organic fibers which are used for manufacturing carbon fibers of carbon fibers and 40-5wt% pulp and binder is produced in a sheet with a paper making machine. The sheet is impregnated with an organic high molecular substance, and molded and cured with a heat press, and cut in a desired form, then carbonized in an atmosphere of inactive gas at 800 deg.C under a pressure of 2-50g/cm<2> to form an electrode substrate with a rib 1 and a groove 2 for a fuel cell. Thereby, a flat carbon electrode having homogeneousness is readily manufactured and productivity is increased.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is a porous carbon with ribs! , relates to a novel method for manufacturing poles. More specifically, the present invention relates to a method for producing a thick ribbed porous carbon sludge by impregnating a sheet obtained by a papermaking method, followed by cutting and thermal firing.

FIG. 1 attached herewith shows a ribbed carbon electrolytic shield, in which reference numeral 1 indicates a rib portion and reference numeral 2 indicates a line portion.

(Prior Art) Conventionally, as a method for obtaining a ribbed carbon electrode, a method has been used in which a carbon fiber sheet made of carbon fibers together with a binder is fired, and the obtained carbon plate is mechanically grooved. However, the carbon plate obtained using 6r2 is very hard, so it is difficult to cut thin grooves, and it is less flexible, so it easily breaks, making it difficult to handle and having poor workability. Ta.

(Objective of the Invention) An object of the present invention is to improve the above-mentioned drawbacks and to provide a method for manufacturing a ribbed porous carbon electrode of low cost and high quality.

(Structure of the Invention) The present invention provides a mixture comprising 60 to 95% by weight of at least one fiber selected from organic fibers for producing carbon fibers and carbon fibers and 40 to 5% by weight of a binder for pulp and/or paper making. Organic polymer VL is added to the sheet obtained by papermaking.
Obtain an impregnated sheet by impregnating it with a bath liquid of J quality, preferably pile up the impregnated sheet and perform a molding hardening treatment with a press,
Next, after cutting and performing infusibility treatment if necessary, at a temperature of 800°C or higher in an inert gas atmosphere,
This is a method for producing a porous carbon-containing electrode, which is characterized by heating and carbonizing under a pressure of preferably 2 to 502/d.

The constituent elements of the present invention will be reviewed below.

<Raw material fibers> The organic fibers for producing carbon fibers used in the present invention include organic fibers used in Jintong when producing carbon fibers, such as regenerated cellulose fibers, pitch fibers, phenol fibers, and polyacrylonitrile fibers; The fiber is suitable,
Thickness: 0.5 to 15 denier, length: 2 to 15 m, preferably 0.5 to 8 denier, length: 1.
Those with a diameter of 5 to 10 mm are selected depending on the purpose and used alone or in combination of two or more.

In addition to cellulose pulp, various synthetic pulps are suitable as the pulp used in this invention, and these pulps act as a binder for organic fibers during paper making.

Carbon h1. Organic fibers for textile manufacturing and carbon fibers are used in a ratio of 60 to 95% of the papermaking mixture.

If the amount of organic fibers and carbon fibers used for manufacturing carbon fibers is less than 60%, it becomes difficult to control the pore diameter, porosity, etc., and the porosity becomes too low, making it impossible to obtain a good sheet. If it exceeds %, it is difficult to form a good sheet during paper making.

<Binder> As a binder for papermaking, for example, fibers that do not dissolve in cold water but dissolve in hot water, such as polyvinyl alcohol fibers, various synthetic pulps, and rayon for papermaking, and are generally commercially available as binders for papermaking are used. be able to.

Synthetic resin emulsions can also be used as binders for papermaking.

The pulp and/or papermaking binder is used in an amount of 40 to 5M% of the papermaking mixture.

In order to maintain wet strength, it is preferable to mix pulp and papermaking binder in a total amount of 5N or more.

Paper making method〉 Paper making can be done by either the normal wet method or dry method.
When the sheet density is low, the dry method is suitable, and when the sheet density is relatively dense, the wet method is suitable.

Organic polymeric substances> Examples of organic polymeric substances used for impregnation include phenolic resins, epoxy resins, unsaturated polyester resins, thermosetting resins such as polydivinylbenzene, vinyl chloride resins, vinylidene chloride resins, and vinyl fluoride resins. , thermoplastic resins such as vinylidene fluoride resin, acrylonitrile resin,
Furthermore, materials such as lignin, pitch or tar may also be used.

The preferable properties of these polymer compounds are that they are soluble in some solvent or melt at daytime temperature during heat treatment, and that after carbonization with a carbon content of 30% or more, carbon can be used as a carbonaceous binder. It is a thermosetting resin (preferably 1M resin) that helps with the M content in the fibers.

The mixed paper is immersed in the M machine polymer vlJ negative bath solution or dispersion. If the amount of impregnated paper that resists the layer is too small, the binder effect and the carbonization yield during carbonization will be poor, and if it is too much, it will be difficult to adjust the porosity due to blockage, and it will become brittle. The preferred amount of impregnation is 20 to 200% of the weight of the mixed paper, more preferably 3
It is 0-120%.

<Press treatment> The basis weight of the sheet is set to the required weight based on the thickness and density of the final carbon electrode, and press treatment is performed. Press molding is performed to give the final carbon electrode the necessary thickness, shape, porosity, and pore size, and at this time, heat treatment may also be used to harden the resin 7 in the impregnated sheet. This curing treatment made it possible to maintain a constant thickness of the sheet and at the same time obtain a flat sheet. Furthermore, the porosity and pore diameter of the carbon plate can be changed arbitrarily by adjusting the press pressure.

During the above press treatment, a thick carbon electrode can be easily obtained by stacking a required number of thin impregnated sheets, preferably three or more sheets, and performing the press treatment in the same manner. The press lamination and curing method of the present invention has made it possible to laminate porous sheets, which are normally difficult to manufacture due to the risk of peeling. When stacking impregnated sheets, stacking them both vertically and horizontally will eliminate the orientation of the sheets, resulting in a carbon electrode with a uniform thickness without cracks or cracks that are less prone to distortion during heating and carbonization. is obtained. The press heating conditions are 150~
220°C for 1 to 60 minutes is suitable.

<Grooving> The press-formed sheet is then grooved with desired dimensions by conventional mechanical cutting. The sheet after press forming is not carbonized, so it is flexible and easy to handle.
Furthermore, machining is easier than with carbon plates, and products with good machining accuracy can be obtained.

Infusibility and firing> The sheet subjected to the above-mentioned cutting process is required to be infusible and then fired to form a carbon electrode.For this infusibility treatment, organic fibers such as polyacrylon fibers, IJ fibers, and pitch fibers are added. It is particularly effective when thermosetting dRBF1 such as phenol resin is used as the organic polymer material, and has a remarkable effect on improving carbonization yield and sheet strength. The treatment conditions for infusibility are not particularly specified, but for example, 150~
Cine-melting is carried out by heating the mixed paper to which the organic polymer substance has adhered at 350° C. for several tens of minutes to several tens of hours in an air gas atmosphere.

Then, the electrode is heated and fired at a temperature of 800° C. or higher in an inert gas atmosphere to form a ribbed porous carbon electrode containing a carbonaceous binder. By changing the heat treatment temperature, it is possible to control the electrical resistance value of the final product. Moreover, when the above-mentioned heating and firing is performed while applying a load at a pressure of 2 to 501/-, a carbon plate having extremely high strength, uniform thickness, and flatness can be obtained.

(Effects of the Invention) According to the present invention, the productivity of carbon electrodes with IJ buttons has been improved, and it has become possible to easily obtain uniform and flat carbon electrodes with little directionality. In addition, selection of the thickness of raw material fiber,
By adjusting the formulation and press treatment, it has become possible to freely and easily control the pore size and porosity of the plate, which is a particular problem when used as an electrode base material for fuel cells.

(Examples) In order to make the present invention easier to understand, Examples are shown below, but the following Examples do not limit the present invention.

In addition, parts and % in the examples are parts by weight and % by weight, respectively.

Examples 1 to 3 Polyacrylonitrile fiber with a thickness of 3 denier and a length of 5 baits, pitch fiber, Canadian freeness 500 m +++
Add water to Noguruzo (NUKP) and polyvinyla tvcol M fiber (Ri5 Vg, VP B 105-2X 3) in the proportions shown in Table 1 to obtain a slurry, and process using a circular wire paper machine in a conventional manner. A sheet with a basis weight of 200 f/- was made. This sheet was coated with phenol resin (PR-514 manufactured by Sumitomo Durez).
04) N amount 1 with phenol resin impregnated in 40% aqueous solution
00%/c)) was dried at a temperature of 105°C.

Next, the number of sheets shown in Table 1 were stacked vertically, horizontally, and alternately, pressed to a thickness of 2.5 m, and simultaneously heated at 180°C.
Heating geography was performed for 15 minutes.

Next, the obtained press-formed sheet was cut with a metal tool to form a groove of 2.4 cm wide x 1.75 cm high.
They were placed on one side of the sheet at 4 m intervals.

The cut sheet was heated and infusible in air at 220° C. for 4 hours, and then heated and carbonized in a nitrogen gas atmosphere furnace at 1000° C. for 1 hour under a load pressure of 7 f/−. A ribbed porous carbon electrode was obtained which was uniform, had good flatness without delamination, and had a good lip shape. Results first
It is shown in ff.

Table 1 Note 1) Pore diameter and porosity were measured by mercury intrusion method.

Note 2) Resistance was measured using the Wheatstone bridge method.

[Brief explanation of the drawing]

FIG. 1 shows a sectional view of the lipped porous carbon electrode of the present invention. The numbers in the drawings represent the following, respectively. 1.Reply Department 2.Applicant: Oji Paper Co., Ltd. Agent: Patent Attorney Minoru Isaka Figure 1

Claims (1)

[Scope of Claims] 1) Making paper from a mixture consisting of 60-951% by weight of at least 100% fibers selected from organic fibers for producing carbon fibers and carbon fibers, and 40-51% by weight of pulp and/or binder for papermaking. The obtained seeds are impregnated with a bath liquid prepared by Yuripolymer WJ to obtain an impregnated sheet, which is heated and pressed to form and harden.Then, cutting is performed, and if necessary, infusible treatment is performed. After that, heat carbonization at a temperature of 800℃ or higher in an inert gas atmosphere.
A method for manufacturing a porous noble carbon 14L pole with ribs. 2) The method for manufacturing a ribbed porous carbon electrode according to claim 1, wherein an impregnated sheet is used as a core layer and thermal press treatment is performed. 3) The method for producing a ribbed porous carbon according to claim 1 or 2, wherein the carbonization is carried out under a load and pressure of 2 to 50 t/-.