JPS6111431B2 - - 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 an object thereof is to improve leakage resistance. In this type of battery, a sealant consisting of asphalt pitch and mineral oil such as process oil is generally interposed between the battery container, metal sealing plate, and gasket to ensure liquid tightness inside the battery. The above sealants do not have sufficient liquid-tightness,
The leak resistance was rather poor. As a result of intensive study in light of the above circumstances, the inventors of the present invention discovered that naphthenic or paraffinic process oils were conventionally used as mineral oils, but instead of this oil, aromatic process oils were used. It was found that the sealant has an excellent liquid-tight effect, and this invention was made. This 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 powder and press-molding it. 2 is a mixture of an amalgamated zinc active material and a sizing agent such as sodium polyacrylate and carboxymethyl cellulose, which is then subjected to alkaline electrolysis. The cathode agent 3 is made into a gelatinized material by injecting most of the liquid, and 3 is a separator consisting of a liquid-absorbing 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. . Reference numeral 7 denotes a sealing agent interposed in a small gap 8 at the interface between the gasket 6, anode can 4, and cathode terminal plate 5, and this sealant is made of asphalt pitch and aromatic process oil. The asphalt pitch may be a straight asphalt pitch obtained as a residue after subjecting an asphalt-based crude oil to atmospheric distillation and steam or vacuum distillation, but is more preferably obtained in the same manner as above from a semi-asphalt-based crude oil. It is best to use blown asphalt pitch, which is produced by oxidative polymerization by blowing air into the residue under heating and has excellent alkali resistance, water resistance, and weather resistance. Aromatic process oil has the function of imparting appropriate tackiness or flexibility as a sealant when used in combination with asphalt pitch, and is commercially available as a petroleum distillate with an aromatic content of 60% or more. It has physical properties such as a refractive index of 1.55 or more, a specific gravity of 0.95 or more, and an aniline point of 60°C or less. By the way, both conventional naphthenic process oils and paraffinic process oils have less than 60% aromatic components, and the refractive index of naphthenic process oils is less than 1.55 and greater than 1.50, and the specific gravity is less than 0.95 and 0.90. In addition, paraffinic process oils have a refractive index of less than 1.50 and a specific gravity of less than 0.90. The inventors used the above-mentioned aromatic process oil according to the present invention in place of the conventional process oil having a low refractive index and low specific gravity, which has a small amount of aromatic components, and applied it to asphalt pitch normally. When blended with 10 to 50% by weight, preferably 20 to 40% by weight, we succeeded in greatly improving leakage resistance as seen in the test examples below, but due to the aromatic process oil. At present, it is not necessarily clear what mechanism of action is responsible for this leakage-resistant effect. A sealant containing both of the above components is usually prepared by mixing asphalt pitch and aromatic process oil and dissolving this in an appropriate organic solvent such as toluene, benzene, or xylene. The agent is applied in advance to the required portions of the anode can 4 and the cathode terminal plate 5 or gasket 6, and then air-dried to intervene in the gap 8. As is clear from the above configuration, gasket 6
If a sealant 7 made of asphalt pitch and aromatic process oil is interposed between the interfaces between the anode can 4 and the cathode terminal plate 5, the sealant 7 made of asphalt pitch and conventional process oil can be inserted. The sealing function is significantly higher than that using 200 mm, and the leakage resistance is greatly improved. The table below shows that in the above configuration, blown asphalt pitch was used as the asphalt pitch, and AH manufactured by Izumi Kosan Co., Ltd. was used as the aromatic process oil.
−10 (specific gravity 0.9949, refractive index 1.5589, aniline point 32
The leakage resistance test results of the button-type alkaline battery A of the present invention using blown asphalt pitch and naphthenic process oil (KL-40 manufactured by Izumi Kosan Co., Ltd.; specific gravity 0.9454, refractive index
Conventional battery B using a battery consisting of
and blown asphalt pitch and paraffin-based process oil (manufactured by Izumi Kosan Co., Ltd.) as a sealant.
WP-75; specific gravity 0.8720, refractive index 1.4772) is shown in comparison with the conventional battery C, which uses a battery consisting of WP-75; I can understand that. In addition, in the leakage resistance test, 100 batteries were tested for each battery A, B, and C at a temperature of 45°C and a relative humidity of 90%.
The number of batteries that showed leakage after being left in an atmosphere for three months was investigated. 【table】

[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. 7... Sealant, 8... Interval.

Claims (1)

[Claims] 1. A button-type alkaline battery characterized in that a sealant 7 made of asphalt pitch and aromatic process oil is interposed between the battery container, the metal sealing plate, and the gasket.