JPS6040141B2 - Alkaline battery manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the sealing part of an alkaline battery such as a silver battery, a mercury battery, a nickel cadmium battery, an alkaline manganese battery, etc., and aims to improve leakage resistance.

Conventionally, various attempts have been made to seal the gap between the sealing plate and gasket of alkaline batteries using sealants such as asphalt pitch, microcrystalline wax, polyisobutylene, and low polymerization degree fluororesin, but these sealants do not seal the gap between the sealing plate and the gasket. The board may have poor adhesion to the gasket,
It does not have sufficient alkali resistance and may be altered by the electrolyte, making it unable to perform its function as a sealant.
External leakage of electrolyte may occur.

In order to improve this problem, it has been proposed to use a resin polyamide resin with an amine value of 9 or more, which has adhesive properties, an extremely low softening point, and functions as a filler, as a sealant.

Common fatty polyamide resins have relatively good adhesion to metals compared to the sealants mentioned above, and are not altered by alkaline electrolyte, but when the amine value becomes 9 or more, the adhesive strength with metals decreases, In particular, it is difficult to effectively prevent the creep phenomenon of the electrolyte that occurs on the metal surface during high-temperature storage. In this invention, a fatty polyamide resin having an amine value of 8 or less is obtained by reacting an unsaturated fatty acid duplex obtained by thermal polymerization of vegetable unsaturated fatty acids with a diamine such as ethylenediamine or propylene diamine. was given,
The reaction formula is shown below.

However, D in the formula is a C34 unsaturated hydrocarbon group.

The amine value is KOH equivalent to 1 g of fatty polyamide resin, for example American Standard for Testing and Materials (ASTM) No. D2
It can be measured using the 074-6 rainbow method. A liquid made by dissolving fatty polyamide resins with various amine values in alcohol is applied to the surface of the metal sealing plate that will be in contact with the gasket to form a sealant layer, and the adhesive strength of this sealant layer and the sealing plate are evaluated. The assembled button-type alkaline battery was heated at 2 pu○ for 1G hours for 3 hours at a relative humidity of 90%.
Table 1 below shows the rate of leakage when a temperature cycle of 8 hours at 500 °C was repeated for 35 days.

Table 1 As is clear from this table, those with an amine value of 8 or less have high adhesive strength and prevent the creep phenomenon of the electrolyte, and fatty polyamide resins with a low amine value have a high softening point and are heat resistant. Because of its excellent properties, the sealant layer will not soften and be extruded when the battery is left at high temperatures.

As described above, fatty polyamide resins with an amine value of 8 or less have excellent properties, but these values are still not fully satisfactory. The reason for this is that the surface of the cured sealant layer tends to become uneven, and the leakage path of the electrolyte from the sealant layer and the rear surface of the gasket cannot be blocked. Therefore, in this invention, the inner diameter of the gasket is designed to be slightly smaller than the outer diameter of the sealing plate, and the inner surface of the gasket that supports the sealing plate and/or the peripheral part of the sealing plate that contacts the gasket has an amine value of 8 After forming a sealant layer made of the following fatty polyamide resin and iron-bonding the gasket to the peripheral part of the sealing plate, the sealing plate is heated from the outside to soften the sealant layer and utilize the elasticity of the gasket. The film state of the sealant layer is modified to close the bush surfaces of the gasket and sealing plate with the sealant layer.

Next, embodiments according to the present invention will be described with reference to the drawings. As shown in FIG. 1A, a folded hanging part 2 is provided on the periphery of the metal sealing plate 1 which also serves as a cathode terminal, and the outer surface of the hanging part 2 is covered with fat having an amine value of 1.2. A sealant layer 3 is formed by applying and drying an alcohol solution of polyamide resin.

On the other hand, as shown in FIG. 1B, the gasket 4 has an L-shaped cross section by integrally forming a rising part 5 and a receiving part 6 projecting inward at right angles at the lower part of the rising part 5. It is made of elastic synthetic resin such as polyamide resin, polyethylene resin, and polypropylene resin. The inner ridge b of the rising portion 5 is designed to be slightly smaller than the outer diameter a of the sealing plate 1, and when the gasket 4 is iron-fitted to the sealing plate 1,
The rising portion 6 of the gasket 4 is pushed outward and its repulsive force presses the sealant layer 3 over the entire surface.
Next, as shown in FIG. 2, when the central part of the sealing plate 1 is held between the upper and lower sides by the heating jig 7 and heated, the heat is transmitted through the sealing plate 1 and softens the sealant layer 3, and the gasket 4 The sealant layer 3 softened by the pressure is pushed into the fine recesses formed on the surface of the sealing plate 1 and gasket 4 and adheres well, and the sealant layer 3 is free from uneven coating and pinholes. The material also becomes a uniform thin layer due to the softening caused by heating and the pressure of the gasket 4, and is brought into liquid-tight contact with the gasket 4.

Figure 3 shows a button-type alkaline battery using the assembly of the sealing plate 1 and gasket 4 made in this way, and the anode can 8 containing mainly silver oxide, mercury oxide, manganese dioxide, etc. The anode 9, separator 10, and absorbent paper 11 are sequentially inserted, and the sealing plate 1 and gasket 4 filled with the cathode agent 12 made of a mixture of zinc powder and gelled alkaline electrolyte are inserted into the opening of the anode can 8. Then, the open □ end of the anode can 8 is curled inward to seal the battery.

A button-type alkaline battery (1) obtained by softening the fatty polyamide resin layer with an amine value of 1.2 obtained in the above example, and the same fatty polyamide resin layers with an amine value of 3, 5, and 8 were used. Battery (0) Battery (m) and battery (W) of the same type as the battery according to the present invention, in which a sealant layer made of a fatty polyamide resin with an amine value of 1.2 is applied and formed on the periphery of the sealing plate. Table 2 below shows the leakage rate when the alkaline battery (V) was stored at 60 qo for 30 days at a relative humidity of 85%.

Table 2 This invention has the above-mentioned structure, and the sealant layer made of fatty polyamide resin with an amine value of 8 or less has high adhesive strength and has very good adhesion to the sealing board. The electrolyte that attempts to leak along the surface of the sealing plate is effectively blocked by the sealant layer.

In addition, the film condition in the sealant layer can be modified by softening the sealant layer and the elasticity of the gasket, which improves the adhesion between the sealant layer and the gasket, even under harsh conditions as shown in Table 2. Excellent leakage resistance can be obtained.

[Brief explanation of the drawing]

1A and 1B are cross-sectional views of the sealing plate and gasket used in the present invention, FIG. 2 is a cross-sectional view showing the manufacturing state of the present invention, and FIG. 3 is a cross-sectional view of the button-type alkaline battery according to the present invention. . DESCRIPTION OF SYMBOLS 1... Sealing board, 3... Sealing agent layer, 4... Gasket, a... Inner cover, b... Outer diameter. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. The inner diameter b of the gasket 4 is designed to be slightly smaller than the outer diameter a of the sealing plate 1, and the inner surface of the gasket 4 in contact with the sealing plate 1 and/or the peripheral part of the sealing plate 1 in contact with the gasket 4 has an amine value. A sealant layer 3 made of a fatty polyamide resin of 8 or less is formed, and the gasket 4 is attached to the sealing plate 1.
After fitting around the peripheral part of the sealing plate, the sealing plate is heated from the outside to soften the sealant layer 3, and the film state of the sealant layer 3 is modified using the elasticity of the gasket 4. A method for manufacturing an alkaline battery, characterized in that the contact surface between the gasket 4 and the sealing plate 1 is closed by the following method.