JPH0114669B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a leak-proof structure for alkaline batteries. Conventional structure and problems Conventionally, most synthetic resin sealing bodies for batteries have been manufactured by injection molding, but when molten synthetic resin is injected into a mold and cooled, the synthetic resin is It will shrink slightly. Normally, molding molds are designed and manufactured with this shrinkage in mind, but when the shape of the product becomes complex, the degree of shrinkage (sink) may differ in some parts, and it may not be possible to obtain the desired product. be. The presence of a synthetic resin sealing body in alkaline batteries greatly contributes to leakage resistance, and the degree of contact between the surface that contacts the negative electrode current collector when viewed from the leakage path is the key to leakage resistance. . As shown in FIG. 1, in the shape of the conventional synthetic resin sealing body 5, deformation due to shrinkage during cooling is seen on the contact surface with the negative electrode current collector 7, and the negative electrode current collector and the synthetic resin sealing body 5 are deformed due to shrinkage during cooling. There was a problem in that a gap 14 was created between the device and the body, resulting in poor leakage resistance. OBJECT OF THE INVENTION An object of the present invention is to improve the leakage resistance of an alkaline battery by changing the shape of a synthetic resin sealing body. Composition of the Invention In order to achieve the above-mentioned object, the present invention is characterized in that an annular build-up is formed at the connection part between the cylindrical part surrounding the negative electrode current collector of the synthetic resin sealing body and the annular thin film part, This facilitates the flow of resin during injection molding from the cylindrical portion 5b of the sealing body 5 to the annular thin-walled portion 5c and the L-shaped cross-section portion 5a, as shown in FIG. Injection molding is extremely instantaneous, so
After the resin fills the annular thin-walled portion 5c and the L-shaped cross-sectional portion 5a, stagnation is caused in the flow at the annular built-up portion 5d, and due to this stagnation, the amount of resin in the cylindrical portion 5b increases slightly, increasing the resin density. , deformation due to shrinkage of the surface in contact with the negative electrode current collector during cooling of the sealing body is suppressed. DESCRIPTION OF EMBODIMENTS The present invention and its embodiments will be explained below.
FIG. 2 shows a cylindrical alkaline manganese battery according to an embodiment of the present invention. In the figure, 1 is a positive electrode can, inside which a cylindrical molded positive electrode mixture 2 made of manganese dioxide and graphite is placed, and inside it is a gel made of caustic potash, a viscous substance, and zinc chloride powder. A shaped negative electrode 3 is inserted through a separator 4. 5 is a synthetic resin sealing body made of relatively soft polyethylene or the like for sealing the opening of the positive electrode can 1, 6 is a negative electrode bottom plate disposed on the outside thereof, and 7 is a negative electrode current collector. A nail-shaped negative electrode current collector 7 spot-welded to the center of the negative electrode bottom plate 6 is inserted into the hole of the cylindrical part 5b of the sealing body 5 while holding the metal blade protrusion 8, and then the negative electrode current collector and the sealing body 5 are inserted. The current collector 7 is inserted into the gelled negative electrode 3, and the sealing body 5 is used to close the positive electrode can 1.
Seal the opening. The sealing body 5 has an L-shaped section 5a sandwiched between the opening of the can 1 and the peripheral flange of the negative electrode bottom plate 6, a cylindrical part 5b surrounding the negative electrode current collector 7, and an annular part connecting 5a and 5b. Thin wall part 5
c, and an annular built-up part 5d provided at the connection part between the cylindrical part 5b and the annular thin part 5c. Furthermore, grooves 5e for gas dissipation are radially provided at several locations on the side of the L-shaped section 5a of the sealing body 5 that contacts the peripheral flange of the negative electrode bottom plate 6. Reference numeral 8 denotes a metal blade protrusion integrally provided with an edge portion 8a that ruptures the thin wall portion 5c of the sealing body 5 for explosion protection when the internal pressure increases. 9 is a positive terminal cap provided with a notch 9a for gas dissipation, 10 is a tube of heat-shrinkable resin such as polyvinyl chloride, 11 and 12 are insulation, and 13 is an exterior can. FIG. 1 is a longitudinal cross-sectional view when the negative electrode current collector 7 is inserted into the conventional sealing body 5 described above.
On the other hand, as shown in FIG. 3, in the sealing body 5 of the present invention, there is no stagnation in the resin flow at the annular built-up portion 5d, which causes deformation of the cylindrical portion 5b during cooling. Therefore, no voids are seen on the contact surface of the cylindrical portion with the negative current collector 7. In addition, the arrows in the sealing body shown in FIGS. 1 and 3 are as follows:
Shows the flow of resin during injection molding. Effects of the Invention We compared the leakage resistance performance (number of cells leaking) between the alkaline manganese battery according to the present invention and a similar alkaline manganese battery using the conventional one shown in Figure 1 for the sealing body. . The results are shown in the table below.

[Table] As shown in this table, the alkaline manganese battery according to the present invention has significantly improved leakage resistance performance compared to the conventional one.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a conventional sealing body with a negative electrode current collector inserted therein, FIG. 2 is a half-cut side view showing a cylindrical alkaline battery according to an embodiment of the present invention, and FIG. 3 is a sealing body of the present invention. FIG. 3 is a vertical cross-sectional view when a negative electrode current collector is inserted into. DESCRIPTION OF SYMBOLS 1... Positive electrode can, 2... Positive electrode mixture, 3... Negative electrode, 4... Separator, 5... Sealing body, 5a... L-shaped section, 5
b... Cylindrical part, 5c... Thin wall part, 5d... Annular built-up part, 5e... Gas dissipation groove, 6... Negative electrode bottom plate, 7... Negative electrode current collector, 8... Blade protrusion, 8a... Edge part, 9... Cap, 9a... Notch, 10... Heat-shrinkable resin tube, 11, 12... Insulating ring, 13... Exterior can, 1
4...Void part.

Claims (1)

[Claims] 1. An alkaline battery comprising a positive electrode can housing a power generation element, a synthetic resin sealing body for sealing the opening of the positive electrode can, and a negative electrode bottom plate disposed on the outside of the sealing body, wherein the sealing body is A cylindrical part surrounding a negative electrode current collector, an L-shaped cross-sectional part held between the negative electrode bottom plate, a peripheral flange, and a positive electrode can opening, and an annular thin film connecting the cylindrical part and the L-shaped cross-sectional part. 1. An alkaline battery, wherein the alkaline battery has a ring-shaped build-up at a connecting part between the cylindrical part and the annular thin film part.