JPH0377623B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a carbon body for electrodes suitable for use in air cells, fuel cells, and the like. Components that carbonize when fired, such as various synthetic resins, are used as materials along with components used as necessary, such as graphite and activated carbon, and are made into carbon bodies for electrodes through kneading, molding, and firing. The micropores that are naturally formed during firing serve as gas passages for air cells and fuel cells, so they are suitable as electrodes by forming a catalyst layer and undergoing water-repellent treatment as necessary. It is used. However, the above-mentioned micropores alone tend to have insufficient gas passage ability. In addition, if the gas passing ability is insufficient, the discharge characteristics will not be good. To describe this in the case of a general air battery, in which an electrolyte is placed in a cathode container and immersed up to the center of a cylindrical anode (using carbon material) having a central hole, the carbon material used in the anode is If the gas passing ability is insufficient, the electrolyte reaction, which is an electromotive reaction, will not proceed sufficiently in the part immersed in the electrolyte due to insufficient gas supply through the central hole, and the gas supply will be insufficient compared to this. is sufficient near the free interface (water surface) of the electrolyte, so only the area near the free interface of the electrolyte becomes a substantial electrolyte reaction area, and therefore the voltage and current that can be obtained become small. will occur. The gas permeability is thought to depend largely on material selection, but it is also thought to depend largely on the molding surface. That is, to explain the case where a cylindrical molded product is obtained by extrusion molding as an example, as a result of the material being oriented in the extrusion direction, the micropores formed by firing also extend in the vertical direction of the cylindrical body, and gas The gas passage from the center hole for storage or gas supply, or in other words, gas supply, to the electrolyte reaction section on the side of the cylindrical body becomes unnecessarily long. The present invention has been made in view of the above-mentioned points, and is made by kneading, molding, and firing a material containing at least a component that carbonizes when fired, and having a hole for supplying gas. In manufacturing a carbon body for an electrode with the side part of the electrode serving as an electrolyte reaction part,
When molding the material, pressure is applied to some of the materials to deform the material to form a layered object, and then some of the material is supplied and pressure is applied to this material to form a layered object. The gist of the present invention is a method for producing a carbon body for an electrode, characterized in that the material is formed into a laminate by repeatedly performing the above steps, and the hollow hole is formed in a direction penetrating the layer surface of the laminate. First, to illustrate the components of the material used in the present invention, the components that carbonize by firing include:
Various synthetic resins including chlorine-containing resins such as polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, chlorinated polyvinyl chloride, and chlorinated polyethylene, furan-based resins, as well as pitch, asphalt, and cellulose. Examples include various organic substances such as derivatives, lignin derivatives, gum arabic, and polyvinyl alcohol. In addition, ingredients used as necessary include:
The above-mentioned graphite and activated carbon, which are used primarily to enhance functionality, such as platinum and palladium for catalysts, their compounds, and metal phthalocyanines, are simply auxiliary agents during production. For example, plasticizers, solvents, stabilizers, etc. are used for the main purpose of depolymerized or sublimated, or those with a low carbonization rate, such as polyethylene, polypropylene, polybutadiene, polyisobutylene, polystyrene, nylon, polymethyl methacrylate, polyethyl methacrylate, poly-
α-methylstyrene, polymethmethylstyrene,
The effects of the present invention are more effectively achieved when trifluorostyrene, poly-α-deuterostyrene, polyester, natural rubber, butyl rubber, polytetrafluoroethylene, rosin, salicylic acid, anthraquinone, naphthacene, and the like are used. Incidentally, materials such as polytetrafluoroethylene which can be easily made into fibers by roll kneading, for example, do not need to be made into fibers in advance. Each of the above-mentioned components can be used alone or in combination of two or more, and the usage ratio is basically arbitrary, and may be used as usual. The pore-forming material differs depending on its type, but in general, the gas permeability can be sufficiently increased even if the proportion used is not very large.For example, in the case of polytetrafluoroethylene, it can be carbonized by firing. A weight ratio of about 10% or less to the components (and optionally used components such as graphite that remain after firing) is sufficient. The above-mentioned materials are kneaded using an appropriate means such as a Henschel mixer, kneader, or roll machine, and then shaped. During this molding, it is important to apply pressure to layer the materials, which will be explained by way of example shown in the accompanying drawings. In FIG. 1, reference numeral 1 is a cylinder, and 2 is a plunger. If a conventional device is used, it is possible, for example, to install a blind stopper in place of the nozzle of the extruder. The material 3 is put into the cylinder 1 and pressed with the plunger 2. At this time, instead of putting all the material 3 in at once, the divided material 31 is pressed with the plunger 2, and then the material 32 is put in and pressed. The pressure applied to each of the divided materials 31, 32, and 33 as described above deforms each of the divided materials 31, 32, and 33 in the horizontal direction of the drawing to form a layered material, and finally It is possible to obtain a laminate in which the material 3 is oriented laterally in a substantially uniform manner in the longitudinal direction of the drawing. Therefore, the more the material 3 can be divided, the better. The stronger the pressure on each segmented material 31, 32, 33, the better; therefore, it is preferable to repeatedly apply pressure.
3 should be placed so that it is somewhat flat. This is to prevent unnecessary disturbance of the deformation of the segmented material that was introduced earlier when the segmented material that was introduced from above is deformed. It is a good idea to perform subdivision or flattening such as flaking. Furthermore, one method is to make the material pressing surface of the plunger 2 a slightly tapered surface rather than a flat surface as shown in the figure. Note that the gas supplying holes are formed by drilling or the like in a direction penetrating the layer surfaces of the laminate. Next, in the example shown in FIG. 2, reference numeral 4 is a nozzle, and 5 is a container. Nozzle 4
The material 6 is discharged into the container 5, and due to relative sliding with the container 5, the discharged material 6 is deformed in the lateral direction in the drawing. That is, the nozzle 4 corresponds to the plunger 2 in FIG. 1, and the container 5 corresponds to the cylinder 1, but from an equipment perspective, it is like attaching the container to the nozzle of an extrusion molding machine, for example. Each word was used. However, the sliding motion between the cylinder 1 and the plunger 2 in the example of FIG. 1 is relative, and even if the cylinder 1 is slid, there is no substantial difference. A certain amount of material 61 is discharged from the nozzle 4, the container 5 is pushed upwards in the drawing to apply pressure for lateral deformation of the material 61, and then the container 5 is moved downward to dispense an additional amount of material 62, and then further. By repeating a certain amount of material 63, it is possible to save the trouble of dividing and adding material 3 in the example of FIG. At this time, the ejection force itself for the material 6 may be intermittent or uniformly continuous. However, in this example, it is necessary to pay attention to the fact that applying pressure may cause the material 6 to be discharged backwards from the nozzle 4 or to form a lump within the nozzle 4. Therefore, it is necessary to make the material discharge force from the nozzle 4 sufficiently strong. be. Furthermore, nozzle 4
There may be more than one material discharge hole. Next, in the example shown in FIG. 3, one method of integrally molding the gas supplying hole will be described. Reference numeral 7 is a nozzle, and 8 is a mold. The word "type" is used here to indicate that the shape of the carbon rod for electrode manufactured according to the present invention can be other than cylindrical.
The mold 8 in this example consists of several mating bodies so that it can be taken out after molding. Further, reference numeral 9 is a pin having an appropriate length, diameter, and cross section. If the pin 9 is located at the center of the nozzle 7 and the mold 8, the hollow hole to be molded will be the center hole, and the pin 9 will be placed at the center of the nozzle 7 and the mold 8.
If you use a book stand instead of a book stand, the number of holes to be formed will be multiple. Moreover, if the pin 9 is made long or short, the hollow hole to be formed becomes a through hole or a hole with a bottom. The method of deforming the material 10 discharged from the nozzle 7 may be considered in the same manner as the example shown in FIG. Furthermore, if the nozzle 7 does not have a discharge hole for the material 10, it can be considered in the same way as the example shown in FIG. As exemplified above, materials molded by other methods that do not depart from the gist of the present invention are fired after undergoing processes such as shaping and drying as necessary.
Furthermore, if necessary, it is subjected to shaping, formation of a catalyst layer, water repellent treatment, etc., and then used as an electrode. Example 1 Polyvinyl chloride 100 parts by weight Graphite 100 Activated carbon 100 Dioctyl phthalate (plasticizer) 60 Stearate (stabilizer) 3 Methyl ethyl ketone (solvent) 150 Nylon fiber (diameter: 7 μm, length 2 mm)
0.002 〃 After kneading with three rolls until it is substantially free of solvent, put a small amount of the shredded material into the cylinder of a ram extruder equipped with a blind stopper, and after applying sufficient pressure with a plunger, Pull up the plunger, put in a small amount of material again, apply pressure with the plunger, repeat this 10 times, and make a diameter of approximately 4.
A rod-shaped body with a length of about 150 mm was obtained. The surface layer of this rod-shaped body was cut using a lathe, and the diameter was 35 mm and the length was 130 mm.
mm cylindrical body, using a drill to a diameter of 15 mm and a depth of 15 mm.
After forming a 120 mm center hole, heat treatment was performed.
As for the heat treatment, the temperature was raised from room temperature to 300°C for 50 hours, and then a firing treatment was performed at 700°C for 1 hour. Examples 2 to 4, Comparative Examples All the same as Example 1 except that the division of the material to be added in Example 1 was changed from 10 times to 20 times, 30 times, and 40 times.
Examples 2 to 4 were made in the same manner as above, respectively.
Similarly, a comparative example in which all the ingredients were added at one time was used. In order to investigate the performance of the electrodes obtained in each of the above examples, a petroleum benzene solution containing 10% paraffin was sprayed on the surface of each of the above, and the petroleum benzine was volatilized to make it water repellent.The positive electrode was then used as an air cell. Configured. The negative electrode is a cylindrical container made of 99.9% zinc, the electrolyte is a 20% sodium hydroxide aqueous solution, the length of the positive electrode in the electrolyte is 100 mm, the load resistance is 4Ω, and the positive electrode is located in the center of the negative electrode. I let it happen. The obtained discharge characteristics are shown in Table 1.

【table】

[Table] In Table 1, the discharge characteristics of each example are superior to those of the comparative example. As described above, according to the present invention, it is possible to obtain a carbon body for an electrode that has good discharge characteristics as a battery.

[Brief explanation of drawings]

The drawings are for showing one embodiment of the present invention, and FIG. 1 is a vertical cross-sectional view of a main part showing an outline of an apparatus as an example of molding according to the present invention, and FIGS. FIG. 2 is a longitudinal sectional view of a main part corresponding to FIG. 1 of the example. 1...Cylinder, 2...Plunger, 3...
...Material, 4...Nozzle, 5...Container, 6...Material, 7...Nozzle, 8...Mold, 9...Pin, 10
……material.

Claims (1)

[Claims] 1. A carbon body for an electrode, which is made by kneading, molding, and firing a material containing at least a component that is carbonized by firing as a main material, and having a gas supplying hole, and the side of the hole serving as an electrolyte reaction part. In manufacturing the
When molding the material, pressure is applied to some of the materials to deform the material to form a layered object, and then some of the material is supplied and pressure is applied to this material to form a layered object. A method for manufacturing a carbon body for an electrode, characterized in that the material is formed into a laminate by repeatedly performing the above steps, and the hollow hole is formed in a direction penetrating the layer surface of the laminate.