JPH0722031A - Alkaline dry battery - Google Patents

Abstract

PURPOSE:To prevent external leakage of an electrolyte by forming an annular projecting part in a part of a negative electrode current collector abutting against a gasket, and tightly fastening a surface of a collector rod with the gasket. CONSTITUTION:A gel-like negative electrode 14 is charged in a hollow part of a positive electrode mix 12 via a bottomed cylindrical separator 13 composed of unwoven fabric of acetalized polyvinyl alcohol fiber. The negative electrode 14 is obtained by mixing a polyacrylic acid as a gelling agent with zinc powder, and agitating and mixing it with potassium hydroxide aqueous solution under reduced pressure. A gasket 2 for sealing these battery contents is positioned at an upper part of a metallic can 11, a collector rod 1 having an annular projecting part is inserted into a boss part 2a thereof, and a metallic sealing plate 4 is arranged in the outer periphery of the boss part 2a. In an upper part of the sealing plate 4 a negative electrode terminal 3 is connected by resistance welding to a head of the collector rod 1, an opening edge of the metallic can 11 is squeezed toward the inside, and tightly sealed by the gasket 2 and the sealing plate 4. Leakage of an alkaline electrolyte is thereby prevented even in high temperature and high moisture storage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved negative electrode current collector rod for alkaline dry batteries.

Conventionally, in an alkaline dry battery in which a negative electrode current collector rod is inserted and sealed in a gasket boss hole portion, polyamide, polypropylene resin or the like is used as a gasket material of the alkaline manganese dry battery. This gasket had a collector rod insertion hole provided in the center boss portion, and a negative electrode collector rod having an outer diameter slightly larger than the hole diameter was press-fitted into this hole. Therefore, the alkaline electrolyte in the battery is prevented from crawling up the surface of the current collector rod and leaking to the outside by tightening with the gasket. In order to obtain more effective sealing, a metal disc is fitted around the outer periphery of the gasket boss to strengthen the tightening.

[0003]

However, if the outer diameter of the current collector rod is made larger than the hole diameter of the gasket boss portion in an attempt to make the tightening too strong, the distortion of the gasket boss portion becomes large and cracks occur over time. The alkaline electrolyte in the battery leaked to the outside and damaged the equipment used.
On the contrary, if the difference between the gasket boss hole diameter and the current collector rod outer diameter is small, the tightening by the gasket is weak, and the alkaline electrolyte crawls on the surface of the current collector and leaks to the outside in a short time, causing the same situation. . As described above, the related art has a problem in suppressing leakage of the electrolytic solution at the gasket boss portion and generation of cracks.

The present invention solves the above-mentioned problems by
The present invention provides an alkaline dry battery in which the surface of a collector rod is sufficiently tightened with a gasket to prevent the electrolyte from creeping up and cracks in the gasket boss portion.

[0005]

According to the present invention, in an alkaline dry battery having a structure in which a negative electrode current collector rod is inserted into a boss hole portion of a gasket, an annular convex portion is formed at a contact portion of the negative electrode current collector rod with the gasket. It is an alkaline dry battery characterized in that

[0006]

[Function] Up to now, the shape of the current collector rod inserted into the boss hole portion of the gasket of the alkaline dry battery is a round bar, or the portion contacting the gasket boss hole is thick, and the portion contacting the negative electrode gel zinc in the battery is thin. A round bar with steps was used. The outer diameter of the current collector rod is larger than the diameter of the gasket boss and is inserted in a press-fit state, and the surface of the current collector rod is tightened by the gasket to prevent the alkaline electrolyte inside the battery from leaking out.

In the gasket boss portion, the volume corresponding to the volume of the current collector rod into which it is press-fitted expands outward to cause strain. Therefore, the larger the difference between the gasket boss hole diameter and the current collector rod outer diameter, the greater the strain. When the boss portion has a large strain and a long time passes, the boss portion may crack and the alkaline electrolyte may leak to the outside. On the contrary, if the difference between the boss hole diameter and the outer diameter of the current collector rod is small in order to reduce the strain, the gasket tightening on the surface of the current collector rod becomes weak, leading to the leakage of the electrolyte solution due to the creeping up of the calcareous electrolyte solution.

According to the present invention, by forming a plurality of annular projections in the portion of the current collector rod that abuts the gasket boss hole sealing tightening portion, the gasket tightening is partially strengthened and the entire gasket boss portion is covered. Dispersing the strain to reduce it prevents the alkaline electrolyte from leaking out,
Moreover, it is an alkaline dry battery in which crack generation in the boss portion due to strain is prevented.

[0009]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 is an external view of a current collector rod 1 having an annular convex portion used in the example, which is made of brass. Reference numeral 1a in the drawing denotes an annular protrusion of the present invention, and three protrusions are provided. In the figure, the straight portion 1b has an outer diameter of φ1.5 mm, and the outer diameter of the annular convex portion 1a has a diameter of φ1.
The width is 8 mm, the width is 0.5 mm, and the shape is substantially arcuate in cross section for smooth insertion of the gasket. The position of the ring-shaped convex portion 1a is set to 1 in accordance with the gasket boss hole abutting portion.
Three heads are provided at equal intervals from the head portion of c, and the total length is 35 mm.

On the other hand, the hole diameter of the gasket boss is 1.2 m
2, the current collector rod 1 is welded to the negative electrode terminal 3 and inserted into the hole 2b of the boss 2a of the gasket 2 together with the metal sealing plate 4 as shown in FIG. FIG. 3 shows an AA alkaline-manganese dry battery assembled using the components thus obtained.

Reference numeral 11 in the drawing denotes a bottomed cylindrical metal can which also serves as a positive electrode terminal. The positive electrode mixture 12 that is pressure-molded into a cylindrical shape is inserted into the metal can 11, and pressure-molded into a hollow cylinder inside the metal can 11. The positive electrode mixture 12 is formed by mixing manganese dioxide powder and carbon powder, granulating the mixture in a predetermined process, and molding.

The hollow portion of the positive electrode mixture 12 is filled with a gelled negative electrode 14 via a separator 13 on the bottomed cylinder made of a nonwoven fabric of acetalized polyvinyl alcohol fiber. The gelled negative electrode 14 is obtained by mixing zinc powder with polyacrylic acid as a gelling agent and stirring the mixture with an aqueous potassium hydroxide solution under reduced pressure.

A gasket 2 made of a polyamide resin for sealing these battery contents is located in the upper part of the metal can 11, and a current collector rod 1 having an annular convex portion 1a is provided on a boss portion 2a at the center of the gasket 2. A metal sealing plate 4 is inserted and installed on the outer periphery of the boss portion of the gasket 2. The negative electrode terminal 3 is joined to the top of the metal sealing plate 4 by resistance welding with the head of the collector rod 1. These components are assembled, the opening edge of the metal can 11 is tightened inward, and the gasket 2 and the metal sealing plate 4 are hermetically sealed.

In the comparative example, as shown in FIG. 4, a straight current collecting rod without an annular convex portion as in the example, the outer diameters of which are φ1.5 mm, φ1.6 mm and φ1.7 m, respectively.
The same alkaline dry battery was assembled with three kinds of m, the total length and the like having the same dimensions as the example.

The alkaline dry batteries of Examples and Comparative Examples were each stored 100 pieces under the conditions of a temperature of 60 ° C. and a humidity of 93%. These alkaline batteries can be stored for 3 days
The results of testing for liquid leakage and cracks in the boss portion every 90 days up to 90 days are shown in Table 1 below.

[0016]

[Table 1]

As is clear from Table 1, in the alkaline dry batteries of the examples, liquid leakage and boss cracking are sufficiently suppressed when stored at high temperature and high humidity. This is because the gasket is sufficiently tightened by the annular convex portion of the collector rod and the strain applied to the gasket is dispersed and reduced.

On the other hand, the alkaline dry battery of the comparative example is
During storage at high temperature and high humidity, leakage current was observed on the 90 mm diameter current collector rod on the 90th day, and 9 mm at φ1.6 mm and φ1.7 mm.
It can be seen that the boss cracks occur on the 0th and 60th days. This is because the tightening of the gasket is weak for the current collecting rod of φ1.5 mm, and the strain of the gasket is large for the current collecting rods of φ1.6 mm and φ1.7 mm.

[0019]

As described in detail above, according to the present invention,
In high temperature and high humidity storage, there is no leakage of alkaline electrolyte,
It is possible to provide an alkaline dry battery in which cracks in the gasket boss portion do not occur.

[Brief description of drawings]

FIG. 1 is an external view of a current collector used in an example of the present invention.

FIG. 2 is a cross-sectional view of an essential part in which a current collecting rod according to an embodiment of the present invention is inserted in a gasket.

FIG. 3 is a sectional view of an alkaline dry battery of the present invention.

FIG. 4 is an external view of a conventional collector bar.

[Explanation of symbols]

 1 Current collecting rod 1a Annular convex part 1b Straight part 2 Gasket 2a Boss part 2b Hole part

Claims (1)

[Claims] 1. An alkaline dry battery having a structure in which a negative electrode current collector rod is inserted into a hole of a gasket, wherein an annular convex portion is formed at a contact portion of the negative electrode current collector rod with the gasket. Dry batteries.