JPS6081761A - Manufacture of sealing body for battery - Google Patents

Abstract

PURPOSE:To improve fluid leakage resistance by providing a resin inflow gate at an arbitrary position on a thin wall part provided concentically with a sealing body. CONSTITUTION:A sealing body 15 is injection-molded using thermoplastic synthetic resin such as polyamide, polyethylene, and polypropylene. The sealing body includes, e.g., an inner side cylindrical part 151, an outer side cylindrical part 152 around the inner side cylindrical part 151 via an annular thin wall part 153 having thickness of about 0.1 to 0.2mm., a stepped part 154 formed on the upper part of the inner side and outer side cylindrical parts 151, 152, and a projecting wall 155 for folding along a peripheral edge of the outer side cylindrical part 152. Such the sealing body 15 is formed by letting melting resin from the resin inflow gate 101 provided at an arbitrary position on the annular thin wall part 153. The sealing body can be formed without producing orientation distortion in a sealing body central portion into which a pyroelectric bar, allowing its strength to be increased and preventing any cracking from being produced.

Description

[Detailed Description of the Invention] The present invention relates to a method for manufacturing a sealing body for an explosion-proof alkaline battery that has a function of discharging gas to the outside when the internal pressure of the battery rises abnormally; .

It is known that alkaline batteries generate a small amount of gas during discharge or storage, but this level of gas generation has not caused any problems for the battery itself or for equipment using the battery. However, in the worst case scenario, if there is a sudden discharge, a short circuit, or an accident, the battery may explode.

For this reason, this type of battery has conventionally been provided with an explosion-proof valve. This explosion-proof valve has an extremely thin part formed in a part of the sealing body, and when the battery internal pressure exceeds a predetermined pressure,
This thin part was torn to allow gas to escape.

However, when molding the above-mentioned sealing body, the gas evacuation function will not work unless the thickness of the thin part is 0.2111111 or less, so the thickness must be designed to be 0.2 mm or less. However, it is very difficult to industrially form a clever body with a thin part with a uniform wall thickness.
In this regard, several moxibustion molding methods have been attempted. Figure 1 shows a battery using a conventional sealing body.
A cathode agent 3 is filled in the center via a separator 4, a cathode sealing plate 8 having a partially cutout part 9 at the periphery is received by the protruding seat 1a and the metal support 7, and the flange of the sealing body 5 is Conventionally, in the case of this type of circular sealing body 5, the resin inlet gate 10 is placed in the center as shown in FIG. It was believed that forming a molded material was good in order to prevent molding defects.

That is, according to this method, the resin inflow gate 10 of the injection molding mold of the sealing body 5 is provided in the blind hole 56 at the center of the sealing body to allow the molten resin to flow radially, thereby preventing the occurrence of weld lines, etc., and improving quality. It was said that a physically stable sealing body 5 could be obtained. However, according to this method, as shown in FIG.
0, it was necessary to penetrate the bottom of the blind hole 56 when inserting the current collector rod 6 into the center of the sealing body. For this reason, there was a drawback that cracks were more likely to grow than breaks. Furthermore, the flow of the molten resin in the vicinity of the gate 10 becomes complicated, tends to cause orientation distortion, and tends to lower the strength. Further, when inserting a current collecting rod 6 having a diameter larger than the diameter of the current collecting rod insertion hole of the sealing body 5, cracks may occur due to the above-mentioned orientation distortion of the resin during long-term storage, leading to creeping.

This invention was made to eliminate the above-mentioned drawbacks.
By providing a resin inflow gate at an arbitrary position on the thin part provided concentrically with the sealing body, it is possible to mold without causing orientation distortion in the center of the sealing body where the current collector rod is inserted, thereby increasing the strength. , and prevents cracks from forming. Furthermore, since the resin inflow gate is located in the annular thin part, the strength of the thin part decreases, so if the thickness of the thin part is about 0.2 mm, the conventional breaking strength of 97 d or more in 100 can be reduced by this molding method. Since the thin wall portion ruptures under a pressure of about 30 to 50 kg/d, it is possible to provide a sealed alkaline battery with improved reliability in terms of explosion protection.

Hereinafter, Alkali Mangami Pond L, which is an embodiment of the present invention, will be described.
The R6 type will be explained according to the drawings.

In FIG. 3, 11 is a cylindrical metal can, and this metal can 11 has a wall thickness of 02 to Q and is made of 4 mm nickel-plated steel plate, stainless steel, nickel, or stainless steel v, x, f.
A crat plate or a steel plate is drawn to have an outer diameter of 18.1 mm and a height of 43 mm. In this case, the diameter of the open end of the metal can 11 is the outer diameter dimension 13.
．． It is expanded to about 6mm. Further, an annular protruding seat 11a is formed along the inner peripheral surface of the metal can 11 near the opening.

The metal can 11 is filled with a power generation element. That is,
In this case, the center of the metal can 11 is filled with a gelled zinc cathode material 13 that is a mixture of an alkaline electrolyte, gelling agent powder, and zinc powder, and around this cathode material 13, vinylon, polypropylene iron, etc. The anode mixture 12 is filled with anode active material powder, a conductive agent such as graphite or acetylene black, and a binder solution in which Bo9 styrene is dissolved in an organic solvent, mixed together, and pressure-molded.

A sealing body 15 is provided on the protruding seat 11a of the opening of the metal can 11. This sealing body 15 is made of polyamide, polyethylene,
It is injection molded using a thermoplastic synthetic resin such as polypropylene, and as shown in FIG.
The outer cylindrical part 152 is connected to the outer cylindrical part 152 through the annular thin part 153 of about nm.
Furthermore, a stepped portion 154 is formed at the upper part of the inner and outer cylindrical portions 151 and 152, and a folding projecting wall 155 is further provided along the periphery of the outer cylindrical portion 152.

Such a sealing body 15 is molded by cooling molten resin through a resin inlet gate 101 provided at an arbitrary position on the annular thin portion 153.

Then, the sealing body 15 inserts a brass current collector rod 16 derived from the cathode material 13 into the hollow part of the inner cylindrical part 151, and also inserts the outer cylindrical part 152 into the protruding seat 1 of the metal can 11.
It is placed on 1a. Furthermore, the stepped portion 154 of the sealing body 15
A ring-shaped metal support J-17 is installed on the V! There are 6.

This metal support 17 is obtained by punching a nickel-plated steel plate, a stainless steel plate, or a 11i plate using a press, and in this case, a metal support of about 0.7 am is used.

Furthermore, a two-pole 4340 plate 18 is placed on this support 17. This sealing plate 18 is made by drawing a steel plate or a stainless steel plate with a wall thickness between 0.2 and 0.3 mm with copper plating on the inner surface, nickel plating on the outer surface, or cladding with these metals, and a peripheral flange 18a for gas discharge. It has a missing part 19. The current collector rod 16 is fixed to the cathode sealing plate 18 by welding or the like. As a result, the sealing body 15, the current collector s
16, the metal support 17 and the cathode sealing plate 18 are integrated.

In this state, the enlarged opening of the metal can 11 is tightened in the radial direction to reduce the diameter, and then the opening of the metal can 11 is bent inward through the folding projecting wall 155 of the sealing body 15 to form the flange of the sealing plate 18. The top of 18a is pressed so as to be brought into pressure contact with the metal support 17 to seal the opening and complete the battery.

Incidentally, an LRG type alkaline manganese battery (A) using a sealing body 15 molded with the resin inflow gate 101 of the injection molding mold of the sealing body 15 on the annular thin part 153 by applying this invention and a conventional injection molding mold Fifty batteries of the same type (CB) each using the sealing body 5 molded with the resin inflow gate 10 placed above the blind hole 56 provided in the center of the sealing body 5 were assembled, and the batteries were placed in an atmosphere at a temperature of 60° C. and a relative humidity of 90%. After storing for 20 and 40 days, the number of leaking samples was examined, and the results shown in the following table were obtained.

To measure the leakage, the alkaline electrolyte that had flowed up onto the top surface of the cathode sealing plate was examined by color reaction using a phenol reagent.

In Table 1, when the cause of leakage of the conventional battery CB) was disassembled and investigated, it was found that it was due to a crack in the inner cylindrical part 151 of the sealing body 5. It was found that the leakage resistance was improved compared to that of

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram showing a conventional alkaline battery, Figure 2
The figure is a sectional view showing a sealing body used in the same battery, FIG. 3 is a rutted configuration diagram showing one embodiment of the present invention, and FIG. 4 is a sectional view showing a sealing body used in the same embodiment. .

Claims (1)

[Claims] A sealing body made of thermoplastic resin and having a thin wall portion in a part, the thin wall portion having a shape concentric with the sealing body (two parts,
A method for manufacturing a battery sealing body, which has a resin inflow gate from an injection molding mold, and forms a sealing body by flowing molten resin through the resin inflow gate.