JPS6124785B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to button-type alkaline batteries such as silver oxide batteries and manganese dioxide batteries, and aims to improve leakage resistance. In this type of battery, a sealing agent mainly composed of asphalt pitch and process oil is generally inserted into a small gap between the anode can that makes up the battery container, the cathode terminal plate that makes up the metal sealing plate, and the gasket. However, depending on the lot of the sealant mentioned above, there have been cases where defective products such as extremely poor leakage resistance or abnormal swelling of the battery have been observed. . The inventors believe that the cause of this is inorganic particles such as sand, iron, and nickel contained in the sealant raw material, especially asphalt pitch, and that these impede the liquid tightness between the gasket, anode can, and cathode terminal plate. We found out that when it comes into contact with the cathode, it forms a local battery and generates hydrogen gas, which causes blistering. Based on this knowledge, we conducted further studies and found that the conventional asphalt pitch Instead, I learned that a new type of sealant made by using a specific unvulcanized rubber and blending it with process oil has fewer of the problems mentioned above, and can particularly exhibit a sufficient liquid-tight effect. , and came to make this invention. The present invention will be explained below based on the drawings. Figures 1 and 2 show an example of a button-type alkaline battery according to the present invention. 2 is an anode mixture made by uniformly mixing conductive powders and press-molding the mixture, and 2 is a mixture of an amalgamated zinc active material and a sizing agent such as sodium polyacrylate or carboxymethylcellulose, which is then subjected to alkaline electrolysis. A cathode material into which most of the liquid was injected and gelatinized, 3 a separator consisting of an adsorption layer such as vinylon-rayon mixed paper, a cellophane layer, and a hydrophilically treated microporous polypropylene film. Reference numeral 4 denotes an anode can constituting a battery container in which the above-mentioned anode mixture 1 and separator 3 are placed, and a part of alkaline electrolyte is injected into the bottom of this can in advance, and the above-mentioned cathode material 2 is filled inside. The cathode terminal plate 5 constituting the metal sealing plate is fitted with an annular gasket 6 having an L-shaped cross section made of synthetic resin such as polyethylene, and the can opening is tightened inward to seal the inside of the battery. . 7 is a sealant interposed in a small gap 8 in the sealing part between the gasket 6, anode can 4, and cathode terminal plate 5, and this sealant is made of a material mainly composed of unvulcanized rubber and process oil, which will be described later. Become. Examples of unvulcanized rubber include A-B-A type rubber such as polystyrene-polybutadiene-polystyrene block copolymer and polystyrene-polyisoprene-polystyrene block copolymer, which have recently been widely used as rubber materials that do not require vulcanization. A three-block copolymer is used. That is, the above A is a block made of a non-elastomer (the meaning of plastomer, that is, a plastic material that does not have rubber-like elasticity at around room temperature), of which polystyrene is a typical example, and the above B is a block made of a non-elastomer (plastomer, that is, a plastic material that does not have rubber-like elasticity at around room temperature), and the above B is a block made of a non-elastomer (a plastic material that does not have rubber-like elasticity at around room temperature), and the above B is a block made of a non-elastomer (plastomer, that is, a plastic material that does not have rubber-like elasticity at around room temperature). This is a block made of an elastomer (having rubber-like elasticity at around room temperature). The process oil that constitutes the sealant together with this unvulcanized rubber is normally used as a so-called softener in rubber molding, but it includes not only those commercially available as petroleum distillates, but also those contained in asphalt pitch. It also includes oils obtained by extracting and separating oil components, and the latter extracted oil is particularly suitable for improving the sealing function. Such process oil is used in a much larger amount than in general rubber molding processes. That is, it is usually 30 to 60% by weight, preferably 40 to 50% by weight, based on the total amount with the above unvulcanized rubber.
% by weight, thereby maintaining sufficient fluidity as a sealant. A sealant containing both of the above components can be prepared by using an organic solvent such as toluene, benzene, or xylene, and adding and dissolving the process oil and unvulcanized rubber, or by mixing both components under heating. After dissolving, the sealant is diluted by adding an organic solvent, and by applying this sealant to the required parts of the anode can 4 and the cathode terminal plate 5 or gasket 6 in advance and drying it, the above-mentioned sealant is applied. It is interposed in the gap 8. As is clear from the above configuration, gasket 6
A sealant 7 mainly composed of specific unvulcanized rubber and process oil is interposed in a small gap 8 in the sealing part between the anode can 4 and the cathode terminal plate 5, so that sand, iron, nickel, etc. Compared to conventional sealants that use process oil and asphalt pitch, which often contains inorganic particles such as distillation residue, leakage resistance may be significantly inferior depending on the lot, or batteries may swell abnormally. The proportion of defective products is reduced, and due to the appropriate fluidity of the two compatible components and the elastic properties and adhesive properties of the unvulcanized rubber, a seal is formed when the opening of the anode can 4 is tightened inward. The agent 7 adheres or adheres well to the anode can 4, the cathode terminal plate 5, and the gasket 6, resulting in good leakage resistance comparable to that of conventional asphalt pitch sealants. The table below shows that in the above configuration, Kaliflex TR1101 (polystyrene-polybutadiene-polystyrene type 3-block copolymer) manufactured by Siel Kagaku Co., Ltd. was used as the unvulcanized rubber, and the process oil was extracted with n-butanol from blown asphalt pitch. The button type alkaline battery A of the present invention is made by using 50% by weight of this oil based on the total amount of unvulcanized rubber, and the product name manufactured by Izumi Kosan Co., Ltd. is used instead of oil extracted from blown asphalt pitch as the process oil. Leakage resistance and battery bulging test of button-type alkaline battery B of the present invention, which has the same configuration as battery A above, except that the same amount of AH-10 (aromatic process oil as petroleum fraction) was used. The results are shown in comparison with a conventional battery C in which blown asphalt pitch was used as a sealant in place of the unvulcanized rubber in battery A. In addition, in the leakage resistance and battery swelling test, 100 batteries were tested for each battery A, B, and C, and when they were left in an atmosphere at a temperature of 45°C and a relative humidity of 90% for 3 months, no leakage occurred. The number of batteries in which bulge was observed was determined, and bulge was determined to occur when the battery swelled by 5% or more relative to the total height of the battery before the test.

[Table] As is clear from the above table, battery A of the present invention
It can be seen that batteries B and B have good leakage resistance comparable to that of the conventional battery C, and the occurrence of battery swelling is reliably suppressed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a button-type alkaline battery of the present invention, and FIG. 2 is an enlarged view of the portion shown in FIG. 1. 4...Anode can, 5...Cathode terminal plate, 6...Gasket, 7...Sealant, 8...Gap.

Claims (1)

[Claims] 1. An A-B-A type three-block copolymer is filled in the gap 8 in the sealing portion between the anode can 4 constituting the battery container and the cathode terminal plate 5 and gasket 6 constituting the metal sealing plate. A button-type alkaline battery characterized by interposing a sealant 7 mainly composed of unvulcanized rubber and process oil. 2. The button-type alkaline battery according to claim 1, wherein the process oil in the sealant 7 is 30 to 60% by weight based on the total amount of the unvulcanized rubber.