JPS6224905B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a battery having a substantially L-shaped cross section manufactured by injection molding of synthetic resin and to improvements in packing. In order to manufacture battery packing by injection molding, for example, as shown in FIGS. 4a and 4b, molten resin is injected into the cavity 26 of a mold 25 cooled at high pressure through a gate 23, and the resin 27 is divided into two parts. This is done by causing the resin to flow inside the cavity 26 and joining the ends to form an annular body, but the temperature of the joint portion of the resin flowing inside the cavity, called the weld 24, has slightly decreased. Since it is formed by joining resins, the resins do not melt sufficiently, and it also contains impurities such as mold release agent sprayed on the cavity surface and heat-degraded resin, so its strength is different from that of other materials. It is weaker than the other parts, and is shaped like a groove with a slightly smaller diameter than the other parts. Therefore, when packing with such welds is assembled into a battery, the packing may break at the weld, or insufficient clamping force can be obtained at the weld, or if the weld groove is large, electrolysis may occur. Since it forms a leakage path for the liquid, it becomes a cause of liquid leakage, and the leakage resistance of the battery decreases. This invention was made in view of such circumstances, and in a battery packing having an annular and approximately L-shaped cross section manufactured by injection molding of synthetic resin, the rising outer edge of the outer circumferential side of the packing is molded into a molding die. If the molding mold has one gate, the gate position is on the inside of the bottom of the packing, which is directly opposite the gate, or if the molding mold has multiple gates, it is at the intermediate position between each adjacent gate. A protrusion is provided on the inner side of the bottom of the packing,
By forming a weld on the protrusion, a decrease in strength due to the weld is prevented, packing performance is improved, and leakage resistance of the battery is improved. The position where the above-mentioned weld occurs is the position where the molten resin flowing in the cavity of the molding die joins. Specifically, as explained below based on the drawings, the weld is formed at the gate of the molding die. In the case of a single gate, this is the position directly opposite the gate, and in the case of multiple gates, it is the intermediate position between adjacent gates. Next, the present invention will be explained based on the drawings. Figures 1 and 2 are plan views showing embodiments of the packing for batteries according to the present invention, and each packing 1 is annular and has an L-shaped cross section with a horizontal portion called the bottom and a rising portion on the outer circumference side. However, in FIG. 1, one protrusion 2 is provided on the packing 1, and in FIG. 2, two protrusions 2 are provided. The packing shown in FIG. 1 is made by injection molding using a one-point gate, and the protrusion 2 is formed at the position where the weld occurs, that is, at the position directly opposite the gate 3. Although the protrusion 2 can be provided in any direction, it is effective, but if it is provided on the outer circumferential side or the upper surface side, it will get in the way of sealing, so it is provided on the inner side of the packing 1 as shown in the drawing. The packing shown in Fig. 2 is made by injection molding using two gates, and the protrusion 2 is provided on the inner side of the bottom of the packing 1 at the position where the weld occurs, that is, at the middle position between the gates 3. . When the protrusion 2 is provided on the packing 1 in this way,
The following effects are achieved. To explain based on FIG. 1, the protrusion 2 has a cross section L
If it is provided at the bottom of the letter-shaped packing 1, that is, on the inside of the horizontal part, when manufacturing this packing 1, the molten resin injected into the mold from the gate 3 will
It divides into two parts and flows inside the cavity, and gate 3
They reach point X, which is directly opposite the
Since a corresponding concave part is provided in the mold, the resin whose temperature has decreased slightly and contains impurities such as a mold release agent and thermally deteriorated resin, which is the leading part of the flowing resin, is removed from the protrusion 2. The weld 4 is formed by being pushed into the concave portion and joining there. Then, the outer peripheral side and upper surface side of the protrusion 2 formed by the resin flowing into the leading portion are filled with the resin flowing later. The resin that flows after this contains almost no impurities or thermally degraded resin mentioned above, and is at a high temperature, so there is a clear weld in the area formed when the resin that flows after this collides with each other. It has the same mechanical strength as other parts without causing any deterioration in bonding strength. Rather, since the cross-sectional area of the protrusion 2 becomes larger, the strength becomes greater than that of other parts.
The protrusions 2 also have the effect of preventing the packings 1 from overlapping each other during the battery manufacturing process. The formation position and size of the protrusion 2 are determined based on the fact that the formation position and size of the weld can be predicted from experience depending on the number of gates. For example, as an example of the size of the protrusion 2, in the case of packing with a cross-sectional area of 0.6 mm ² and one gate, the protrusion amount of the protrusion 2 (see H in Figure 1) is approximately 0.5 mm, and the bottom width (see H in Figure 1) is approximately 0.5 mm. (see W in Figure 1) is approximately 1 mm, and the thickness of the protruding portion is approximately 0.15 to 0.25 mm. FIG. 3 shows a cross-sectional view of a button-type alkaline battery incorporating the packing 1 of the present invention.
5 is an anode mixture formed by pressure molding a mixture powder consisting of 100 parts by weight (parts by weight, same below), 20 parts of manganese dioxide and 20 parts of phosphorous graphite; 6 is the periphery of the anode mixture 5 7 is a microporous polypropylene film placed on the anode mixture 5, a separator made of cellophane and vinylon-rayon mixed paper, and 8 is a cathode material having zinc as the cathode active material. , 9 is the cathode can, packing 1
is disposed between the opening of the anode can 10 and the cathode can 9, and by tightening the opening edge of the anode can 10 inward, the inside of the battery is sealed. This battery uses a 35% by weight caustic potassium aqueous solution in which 5.2% by weight of zinc oxide is dissolved as an electrolyte. The packing 1 built into the battery is made of nylon 11, and has an outer diameter of 11 mm, an inner diameter of 8.8 mm, and a maximum height.
1.1mm, cross-sectional area ^0.6mm2 , L-shaped in cross section, with 2 protrusions.
is provided on the inner side of the bottom of the packing 1, and its protrusion amount is 0.5 mm, the bottom width is 1 mm, and the thickness of the protruding portion is 0.20 mm. Such a battery A and a battery B incorporating a packing manufactured by injection molding without providing a protrusion for forming a weld were heated at 60°C and a relative humidity of 90%.
Store it for 20 days and check the number of batteries that have leaked.
The results are shown in Table 1. Note that batteries A and B
In both cases, the surface of the cathode can is treated with a treatment agent containing benzotriazole as the main component, and an asphalt compound containing blown asphalt as the main component is interposed between the packing and the anode and cathode cans. Surface-treating the cathode can with a benzotriazole-based treatment agent as described above forms a benzotriazole film on the cathode can, creating a strong bond between the benzotriazole and the copper surface of the cathode can. Through chemical bonding, the benzotriazole film prevents electrolyte leakage due to creep on the copper surface of the cathode can, and the fine gaps that occur between the packing and the anode and cathode cans are filled with blown asphalt. After taking measures to prevent electrolyte from leaking from minute gaps that occur at the contact surfaces between the packing and the anode and cathode cans by filling them with asphalt compound,
This is because it is preferable to investigate differences in leakage resistance based on differences in packing welds. The number of batteries used in the test was 1000 each for batteries A and B.

[Table] As shown in Table 1, battery A using the packing of the present invention has better leakage resistance than battery B using conventional packing. The packing of the present invention is applicable not only to the above-mentioned button-type alkaline batteries but also to various batteries such as cylindrical alkaline batteries, manganese dry batteries, and non-aqueous electrolyte batteries. Furthermore, the present invention is applicable not only to packing using one-point gates and two-point gates as illustrated, but also to packing using three or more multi-point gates. Further, in the embodiment, packing having an L-shaped cross section has been described, but the packing does not have to be exactly L-shaped as long as the cross-section is approximately L-shaped.
The term "shaped packing" includes both packing that is approximately L-shaped in cross section and packing that is exactly L-shaped in cross section. As described in detail above, the present invention provides an annular battery packing having an approximately L-shaped cross section and is manufactured by injection molding of synthetic resin, and in which a projection is provided at a position where a weld is formed, and a weld is formed on the projection. Therefore, strength reduction due to welding is prevented,
It has improved packing performance.

[Brief explanation of the drawing]

Figures 1 and 2 are plan views showing embodiments of the battery packing of the present invention, Figure 3 is a sectional view of a button-type alkaline battery incorporating the battery packing of the present invention, and Figures 4a and 4b are FIG. 2 is a plan view showing a simplified state of manufacturing conventional battery packing by injection molding, with the upper part of the mold removed. 1...Battery packing, 2...Protrusion, 4...
Weld.

Claims (1)

[Claims] 1. In an annular and approximately L-shaped cross-section battery packing manufactured by injection molding of synthetic resin, the rising outer edge on the outer circumference of the packing is the gate position of the mold, and when the mold is a one-point gate. A protrusion is provided on the inner side of the bottom of the packing, which is directly opposite the gate, or, if the mold has multiple gates, on the inner side of the bottom of the packing, which is an intermediate position between adjacent gates. Packing for batteries characterized by forming a weld.