JPS6288273A - Manufacture of catalytic sheet - Google Patents

Abstract

PURPOSE:To uniform the permeability of air by forming a catalytic sheet while mixing an aqueous dispersion of manganese oxide, active carbon, carbon black and fluororesin then uniforming the grain size and applying over a screen. CONSTITUTION:An aqueous dispersion of manganese oxide, active carbon, carbon black and fluororesin is mixed then the grain size is uniformed smaller than 35 mesh. Then the uniformed catalyst is applied in sheet over a metallic screen made of stainless steel thus to form a catalytic sheet 7. Thereafter, a porous fluororesin film 8 is applied tightly over one face to produce an air electrode 9 which is assembled with a zinc electrode 16 to constitute a button type or a tubular air cell. Consequently, the catalytic sheet 7 can be uniformed to uniform the air permeability with reduced fluctuation resulting in an air cell having uniform discharge characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a catalyst sheet used as an air electrode in a button-type air cell, a cylindrical air cell, and the like.

Conventional technology Conventionally, button-type air batteries are manufactured as follows.

First, catalyst particles such as activated carbon, precious metals, and manganese oxide are sufficiently kneaded with an aqueous fluororesin dispersion to form a paste, which is then applied directly to the metal screen and dried to create a catalyst sheet. A porous fluororesin membrane is adhered to one side to form an air electrode, the air electrode and separator are incorporated into the positive electrode case, and the zinc negative electrode and alkaline electrolyte are incorporated into the sealing plate. After coupling, the battery is sealed and sealed. was.

Here, the reason why the fluororesin dispersion is mixed into the catalyst particles is to make the catalyst particles water repellent so that all the oxygen in the air is used as a positive electrode active material, so that oxygen can easily diffuse into the catalyst.

Problems to be Solved by the Invention However, since a dispersion of fluororesin is mixed into the catalyst particles and all oxygen in the air is used as a positive electrode active material, it is necessary to make the catalyst particles water repellent so that oxygen can easily diffuse into the catalyst. Even for the purpose of retention, if the paste-like mixture after kneading is partially lumped or has areas with different densities, it may be necessary to apply it directly to a metal screen and dry it to make a catalyst sheet. 5 Even if a porous fluororesin membrane is closely attached to one side to form an air electrode, the air electrode may have uneven thickness.
This resulted in an air electrode with varying air permeability. When button-type air batteries were made using this air electrode, variations occurred in the discharge characteristics of the batteries, making it impossible to produce uniform air batteries with little variation.

In such a conventional configuration, the air electrode has a variation in air permeability, and when it is made into a battery, the discharge characteristics vary, making it impossible to create a uniform air battery.

The present invention has discovered a method for uniformly manufacturing a catalyst sheet constituting an air electrode, which has no uneven thickness, has an appropriate air permeability, and is capable of configuring a uniform air electrode, thereby improving the discharge characteristics of a battery. The purpose is to provide an air battery with less variation.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention mixes manganese oxide, activated carbon, carbon black, and an aqueous dispersion of fluorine resin to form a metal screen, such as an EVA stainless steel material. In the manufacturing process of the catalyst sheet, which is coated in a sheet form on a nickel-plated screen, manganese oxide, activated carbon, carbon blank, and an aqueous dispersion of fluororesin are kneaded, then sized to 36 mesosinus or less, and then This method is characterized by applying this sized catalyst in the form of a sheet onto a metal screen.

Function The catalyst sheet made by this method has a mixed mixture of manganese oxide, activated carbon, carbon black, and an aqueous dispersion of fluororesin that is sized and has a uniform density, making it suitable for metal sulfur IJ+. Even when it is applied and dried, it becomes uniform, and finally, when a porous fluororesin membrane is attached to one side to form an air electrode, the air permeability becomes uniform even when it is used as a so-called catalyst sheet.

An air battery made using a catalyst sheet with uniform air permeability can have uniform discharge characteristics, as will be explained in the following examples.

EXAMPLE A method for manufacturing a catalyst sheet according to the present invention will be explained with reference to FIG.

First, catalyst particles such as manganese oxide, activated carbon, and carbon black are sufficiently kneaded with an aqueous dispersion of fluororesin to form a paste-like kneaded product 1 and a stainless steel screen 2 with a mesh size of 135 mesh. 1 is pressed to pass through a stainless steel screen 2 for granulation to obtain a sized mixed wire material 3.

The sized kneaded material 3 was transferred to the upper roll Aa-1 of catalyst sheet preparation #j9:4 consisting of three parallel wooden rolls 4-1, 4-2, and 4-3 as shown in FIG. Insert between B4-2. As the upper roll B4-2 rotates, the kneaded material 3 is formed into a sheet 6 with uniform density and comes out on the upper roll B4-2 side. The lower roll 4-3 is a roll for filling the screen 6 made of nickel-plated stainless steel material with the mixed material 3 formed into the sheet shape 6, and the sheet that comes out in close contact with the upper roll B4-2 side. The screen 6 is stacked on the lower side of the mixed material 3 formed into a sheet shape 5, and the kneaded material 3 formed into a sheet shape 6 is filled into the screen 6 using an upper roll B4-2 and a lower roll 4-3. . After making the catalyst sheet 7 in this way, it is dried and the screen e
A porous fluororesin membrane 8 is closely attached to the side to form an air electrode 9, with an outer diameter of 11.6 mm and a height of 5.4 m as shown in Fig. 3.
I made a button-type air battery.

This battery is made as follows. First, an air diffusion paper 11 is placed inside the positive electrode case 10, then a water-repellent film made of porous polytetrafluoroethylene is placed in a 12-karat gold film, and the air electrode 9 is placed with the catalyst sheet 7 made in the above method on top. A separator 13 is punched out to have the same diameter as the inside diameter of the case, and then placed on the air electrode 9. Cellophane, porous polyethylene, or polypropylene is then punched out to have the same diameter as the inside diameter of the positive electrode case 10 in the same way as the air electrode 9, and placed on the air electrode 9. do.

On the other hand, a zinc negative electrode 16 and an alkaline electrolyte consisting of an aqueous potassium hydroxide solution are placed in a sealing plate 15 assembled with a sealing ring 14, and after coupling with the positive electrode case 10, the battery is sealed. Note that 17 is a seal paper that closes the air hole 18 of the positive electrode case. The thus obtained product according to the present invention has an outer diameter of 1j and 6 mm.

Battery A with a total height of 5.4 m111 was assembled using a catalyst sheet 7 made without sizing as in the conventional case, and an air electrode made by adhering it to a porous fluororesin membrane 8 on the screen 6 side. For battery B, 0.9v is the final voltage and 62
Table 1 shows a comparison of capacities when discharging with a load resistance of 0Ω (average value of 100 samples and standard deviation σ indicating variation).

Table 2 shows the air permeability of the catalyst sheet made without sizing as in the prior art and the catalyst sheet of the present invention.

The air permeability was measured using an apparatus as shown in FIG. 4 for each sample (n=100). In other words, the catalyst sheet 7 has a diameter of 1
Press it through the O ring 20 so that it has the size of
The pulp A22 on the A chamber 21 side is opened, the pulp B24 on the B chamber 23 side is closed, and the temporary valve A22 on the A chamber 21 side is evacuated to 10 Torr using a separate vacuum pump. After this, the pulp B24 is opened and the A chamber 21 side is
The time required for the degree of vacuum to drop was measured using Torr i.

Table 1 Table 2 Effects of the invention As described above, by adopting the manufacturing method according to the present invention,
The catalyst sheet on the air electrode side had no uneven thickness and had an appropriate air permeability with no variation, and as a result, a button-type air battery with little variation in discharge characteristics as a battery could be obtained.

Furthermore, the present invention is widely applicable not only to button-type air batteries but also to all batteries that utilize air electrodes, such as cylindrical and stationary 9-box types.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the manufacturing process of the present invention, Fig. 2 is a cross-sectional view showing the process of creating a catalyst sheet and filling it into a metal screen, and Fig. 3 is a structure using the catalyst sheet obtained according to the present invention. FIG. 4 is a cross-sectional view of the button-type air cell, and is a schematic diagram of an apparatus for measuring the air permeability of a catalyst sheet. 1... Paste-like mixture, 2... Grading screen, 3... Grained kneaded material, 6
...Screen made of nickel plated stainless steel material, 7...Catalyst sheet, 8...Porous fluororesin membrane, 10...Positive electrode case, 11.
... Air diffusion paper, 12 ... Water repellent film, 13
・・・・・・Separate Lake. Name of agent: Patent attorney Toshio Nakao and 1 other person13
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Claims (2)

[Claims] (1) A process for producing a catalyst sheet in which manganese oxide, activated carbon, carbon black, and an aqueous dispersion of fluororesin are kneaded and applied to a metal screen in the form of a sheet. A method for producing a catalyst sheet, which comprises kneading an aqueous dispersion of carbon black and a fluororesin, sizing the mixture to 35 mesh or less, and then applying the mixture to a metal screen in the form of a sheet. (2) The method for manufacturing a catalyst sheet according to claim 1, wherein the metal screen is a stainless steel material plated with nickel.