JPS62216157A - Enclosed type alkaline battery - Google Patents

Abstract

PURPOSE:To prevent electrolyte leakage for a long time so as to improve a battery performance, by disposing a sealing material made of resin onto an insulation sealing part between a positive and negative electrode cans. CONSTITUTION:An annular insulation packing 6 is interposed onto an insulation sealing part formed between a positive electrode can 1 and a negative electrode can 5, and a covering layer 7 made of styrene, isobutylene, and styren block polymer resin is formed on the surface of cans 1, 5 in contact with the packing 6. The thus formed layer 7 is closely stuck to the packing 6 and the cans 1, 5 without any clearance by excluding a residual water molecular layer so that, during storage of a battery for a long time, closely sticking condition is held, thereby it is possible to prevent leakage of the sealed alkaline electrolyte to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a button-shaped or cylindrical sealed alkaline battery using an alkaline aqueous solution as an electrolyte.

[Technical background of the invention and its problems]

Conventionally, the structure of a sealed alkaline battery is that an electrode body consisting of a positive electrode and a negative electrode is housed in a can that is a combination of a positive electrode can and a negative electrode can, and the insulating seal formed between these is covered with synthetic rubber or In this case, an annular insulating backing made of synthetic resin is interposed to electrically insulate the positive electrode and the negative electrode, and the inside of the battery is sealed.

However, in a sealed alkaline battery having such a structure, the alkaline electrolyte sealed inside the battery gradually leaks through the minute gap formed between the insulating backing and the can, deteriorating the battery performance.

There were problems such as corrosion of equipment to which this battery was installed.

In order to improve this problem, asphalt is applied to the surface of the insulating backing, or an alkali-resistant insulating resin coating is formed on the surface of the insulating backing.

Sealed batteries are being developed. However, even if an insulating backing with such a configuration is used.

A very thin layer of water molecules exists on the surfaces of the positive electrode can, negative electrode can, and insulating backing when stored in normal conditions, and these water molecule layers remain even after battery construction. For this reason,
When a battery is stored for a long period of time, the electrolyte inside the battery is attracted to the outside of the battery through this residual water molecule layer, causing battery leakage, especially in environments below -5°C. When storing batteries, the adhesion and adhesive strength of the asphalt and alkali-resistant insulating resin are significantly reduced compared to when stored at room temperature. Not only was it impossible to improve performance, but it also caused great damage to equipment using batteries.

[Purpose of the invention]

An object of the present invention is to provide a sealed alkaline battery that prevents electrolyte leakage over a long period of time and improves battery performance.

[Summary of the Invention] That is, the sealed alkaline battery of the present invention includes styrene, isobutylene,
It is characterized by disposing a sealant made of styrene block polymer resin.

The styrene/inbutylene/styrene block polymer resin used in the present invention differs from resins used as conventional sealants in that the tensile strength of the film is low.

The bending strength and elongation are constant, with no difference in mechanical properties depending on direction. Moreover, unlike conventional adhesives based on asphalt, natural rubber, acrylic, and emulsions, this styrene/inbutylene/styrene block polymer resin does not contain water or solvents, so it is difficult to bond to objects. The layer of water molecules existing on the surface of the object to be adhered is completely expelled, and each molecule is firmly attached to the surface.
The styrene-imbutylene-styrene block polymer resin is squeezed out until it completely repels water.

Therefore, a battery can be constructed by completely excluding water from the insulating seal. In addition, since it is solvent-free, there is no gas passage when the solvent evaporates, and this allows the liquid path between the inside and outside of the battery to be completely shut off.

Leakage resistance when storing batteries for a long period of time can be significantly improved.

In addition, the styrene/isobutylene/styrene block polymer resin of the present invention hardly loses its adhesive strength even in a low-temperature atmosphere of -5°C or lower; for example, at -20°C, its adhesive strength is four times that of conventional adhesives. has. Therefore, by using the sealant of the present invention, the leakage resistance performance, especially when storing batteries at low temperatures, is significantly improved.

Furthermore, by using a styrene/inbutylene/styrene block polymer resin heat-treated at a temperature of 180°C or lower, more preferably 170°C or lower,
The adhesive strength of the sealant at low temperatures can be increased.

There is no problem in mixing heat stabilizers, thermoplastics, thickeners, etc. with the styrene/imbutylene/styrene block polymer resin as necessary during this heat treatment, and It is also possible to further increase the adhesive strength of the adhesive layer.

In addition to sealing the styrene/imbutylene/styrene block polymer resin into the insulating seal between the positive and negative electrode cans, it is also applied in a layered manner to the surface of the positive or negative electrode can that is in contact with other ordinary insulating backings. Alternatively, a conventional insulating backing surface may be provided along with the ends of the positive and negative cans.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a button-shaped sealed alkaline battery showing an embodiment of the present invention. This battery is assembled with a positive electrode connected through a separator 2 in a cylindrical positive electrode can 1 which also serves as a positive electrode terminal. A container 3 and a negative electrode device 4 are housed therein, and a negative electrode can 5 having a lid shape and also serving as a cathode terminal is placed on top of the container. Then, an annular insulating backing 6 is interposed in the insulating sealing portion formed between the positive electrode can 1 and the negative electrode can 5, and the backing 6
A coating layer 7 made of styrene/isobutylene/styrene block polymer tree 1M is formed on the surfaces of the positive electrode can 1 and negative electrode can 5 that are in contact with.

The positive electrode can 1 is made of nickel-plated copper, for example, and the cathode can 5 is plated with a metal such as tin or copper on the inner surface and with a noble metal such as nickel or gold on the outer surface. The positive electrode mixture 3 is mainly composed of an active material such as mercury oxide, nickel oxide, or manganese dioxide, and a conductive agent such as graphite or acetylene black. Further, the negative electrode mixture 4 is made of, for example, zinc, cadmium, magnesium, or oxides thereof, and is powder-molded.
Alternatively, any mixed gel of this powder, a gelling substance, and an electrolytic solution may be used.

The separator 2 is made of a natural or synthetic fibrous material, and functions to electrically insulate the positive electrode mixture 3 and the negative electrode mixture 4, as well as to impregnate and retain the electrolyte. Examples of the insulating backing 6 interposed in the insulating sealing part include polymer backings such as synthetic rubbers or synthetic resins such as chloroprene, polyethylene, butadiene-styrene copolymer, polypropylene, and polyamide.

Furthermore, a positive electrode can 1 and a negative electrode can 5 are in contact with the insulating backing 6.
The thickness of the coating layer 7 provided on the surface of the
It is preferable that it is μ or more. The coating layer thus formed completely eliminates the remaining water molecule layer and is coated without any gaps between the insulating backing 6 and the positive electrode can 1. It comes into close contact with the negative electrode can 5.

For this reason, even if the battery is stored for a long period of time, the sealed state is maintained, and in order to prevent the sealed alkaline electrolyte from leaking to the outside, it is possible to prevent the sealed alkaline electrolyte from leaking to the outside. However, the present invention is not limited to this, and may be applied to either one. In this case, it is desirable to provide it on the cathode side where leakage is most likely to occur.

Furthermore, as shown in FIG. 2, the present invention forms a coating 8 based on styrene/isobutylene/styrene block polymer resin on the surface of the insulating backing made of the above-mentioned synthetic rubber or synthetic resin to seal the opening of the insulating sealing part. It may be coated.

In each of the above embodiments, the positive electrode can 1 is formed into a cylindrical shape and is placed at the bottom, and the negative electrode can 5 is formed into a lid shape and is placed over the upper opening of the positive electrode can 1. However, by replacing both of them, the negative electrode can 5 is made into a cylindrical shape, and the positive electrode can 1 is made into a cylindrical shape.
A J-lukaline battery having a lid-like structure may be used. Regarding the shape of the battery, not only a button type but also a cylindrical type battery may be used.

Next, specific examples of the present invention will be described.

[Example of idea]

Example 1 As shown in FIG. 1, a positive electrode mixture 3 containing mercury oxide as a main component and a negative electrode mixture 4 consisting of zinc gel were housed in a cylindrical positive electrode can 1 via a separator 2 made of polypropylene. A lid-like negative electrode can 5 was placed on top of this, and an insulating backing 6 made of polyamide was interposed in an insulating sealing portion formed between the positive electrode can 1 and the negative electrode can 5. A coating layer 7 mainly made of styrene/isobutylene/styrene block polymer resin is formed on the surfaces of the positive electrode can 1 and negative electrode can 5 in contact with the insulating backing 6, and a potassium hydroxide aqueous solution is sealed inside as an electrolyte. N I
Type I ice mercury battery No. 1 was created.

In this case, the thickness of the coating layer made of styrene/inbutylene/styrene block polymer resin was 60 μm.

Fifty mercury batteries obtained in this way were left in an atmosphere of 70% humidity at 450°C for one day, and then
% atmosphere for one day, and then repeating the above operation every other day to measure the number of batteries that leaked electrolyte after 6 months and 1 year.The results are shown in Table 1. Shown below.

Comparative Examples 1 to 3 In order to compare with the present invention, mercury battery No. 2 was prepared in which asphalt was used instead of the styrene/inbutylene/styrene block polymer resin in the present invention in the sealing portion where the coating layer 7 was provided in the above example. A mercury battery No. 4 coated with epoxy resin, a mercury battery No. 4 coated with trichlorinated polyethylene were prepared, and an electrolyte leakage test was conducted under the same conditions as in Example 1 above. The results are also listed in Table 1.

The results of the first topsoil confirmed that the product of the present invention did not leak even after one year and had excellent battery performance.

Example 2 As shown in Fig. 2, a JNHN with the same structure as Example 1 described above, in which the opening was covered with a coating 8 made of styrene-isobutylene-styrene block polymer resin with a thickness of 60 μm.
H-type mercury battery No. 5 was created. This battery was also subjected to a leakage test, and the results are also listed in Table 1.

[Effect of idea]

As explained above, the sealed alkaline battery according to the present invention uses a sealant made of styrene/inbutylene/styrene block polymer resin, so that even if the battery is stored for a long period of time, the sealed alkaline electrolyte does not leak out. It is possible to prevent liquid leakage for a long period of time, and its industrial value is extremely large.

[Brief Description of the Drawings] Fig. 1 is a sectional view of a sealed alkaline battery showing one embodiment of the present invention, Fig. 2 is a sectional view of a sealed alkaline battery showing another embodiment of the present invention. FIG. 1... Positive electrode can 2... Separator 3.
...Positive electrode mix 4...Negative electrode mix 5...Negative electrode can 6...Insulating backing 7...Covering layer 8...Coating agent Patent attorney Noriyuki Chika Yudo Kikuo Takehana

Claims (3)

[Claims] (1) Styrene is used in the insulating seal between the positive and negative electrode cans
A sealed alkaline battery characterized by being provided with a sealant made of isobutylene/styrene block polymer resin. (2) Claim 1 characterized in that a coating layer made of styrene/isobutylene/styrene block polymer resin is formed on at least one of the surfaces of the positive electrode can and the negative electrode can facing the inside of the insulating sealing part. Sealed alkaline battery as described. (3) The sealed alkaline battery according to claim 1, wherein the opening of the insulating sealing portion is coated with a styrene/isobutylene/styrene block polymer resin.