JP2000003698A - Gasket, forming method for gasket and cylindrical alkaline battery using gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of cracks in a gasket to be inserted with a current collector bar and split of an unstable explostion-proof safety valve, then to improve liquid-leakage-resistance performance of the cylindrical alkaline battery. SOLUTION: An aperture of a battery case of the cylindrical alkaline battery 6 is sealed by the gasket 1 formed by a molding tool 18 wherein plural pin point gates 24 opening to the bottom of a board space part 20 is formed, and which is composed of an upper tool 18a and a lower tool 18b, further which is provided with an air vent 26 at the parting line of the upper tool 18a and the lower tool 18b and in the upper part of a cylindrical space part 19b. A bent part 2b of a peripheral part 2 of the gasket 1 is formed in 0.20 mm-0.35 mm thickness, and it is split by receiving stress caused by increase of internal pressure of the battery case.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasket having crack resistance and a stable explosion-proof function, a method for molding the gasket, and a cylindrical alkaline battery provided with the gasket and having excellent liquid leakage resistance.

[0002]

2. Description of the Related Art When cylindrical alkaline batteries are overcharged or overdischarged due to misuse or the like, violent gas is generated inside the battery case body, and the internal pressure of the battery rises abnormally. Danger of leaks and possible rupture. For this reason, the cylindrical alkaline battery is provided with an explosion-proof mechanism for quickly exhausting the gas generated inside to the outside when gas is generated and the internal pressure of the battery rises.

[0003] The explosion-proof mechanism described above is generally constituted by a thin film portion formed on a gasket for sealing an opening of a battery case body serving as an explosion-proof safety valve.
That is, in a cylindrical alkaline battery, the stress generated by gas generation and the internal pressure of the battery are concentrated on the gasket, so that the thinnest portion of the gasket formed thinnest is broken, and the gas generated inside the battery is exhausted to the outside. This prevents the battery from bursting due to an increase in internal pressure.

Conventional gaskets are formed of synthetic resin such as nylon or polypropylene, rubber, or the like, and various gaskets formed in different shapes as shown in FIGS. 6 to 9 have been proposed.

A gasket 50 shown in FIG. 6 has a thick cylindrical portion (hereinafter referred to as a hob portion 51) formed in the center with a convex cross section.
Called. ) And a disk-shaped portion (hereinafter referred to as a diaphragm portion 5) formed concentrically with the hob portion 51 on the outer peripheral side of the hob portion 51.
No. 2. ), A thin film portion 53 formed between the hob portion 51 and the diaphragm portion 52 and formed on the upper surface side of the diaphragm portion 52, and a thin film portion formed on the outer peripheral side of the diaphragm portion 52 and having a bent cross section. Outer periphery 54
And is provided. The hob portion 51 has a lower opening 55
The lower part of the inner peripheral surface is formed in a cylindrical shape having a tapered hob hole 55 so that b opens wider than the upper opening part 55a. As shown in FIG.
It is formed in two arcs concentric with the hob 51.

A gasket 60 shown in FIG. 7 has a hob 61 and a diaphragm 62 similar to the gasket 50.
And a thin film portion 63 and an outer peripheral portion 64. The hob 61 has a lower inner diameter larger than an upper inner diameter, and an inner peripheral surface formed in a cylindrical shape having a stepped hob hole 65. As shown in FIG. 10, the thin film portion 63 is formed in two arcs concentric with the hob portion 61, similarly to the thin film portion 53 of the gasket 50.

A gasket 70 shown in FIG. 8 includes a hob 71 formed in a convex cross section and a diaphragm formed concentrically with the hob 71 and inclined toward the upper end surface of the hob 71. And a diaphragm portion 72 formed between the hob portion 71 and the diaphragm portion 72.
The thin film portion 73 formed on the upper surface side of the
2 and an outer peripheral portion 74 which is located on the outer peripheral side and has a bent cross section. The lower end of the hob 71 is the hob 51, 6 of the gasket 50 or the gasket 60.
1 is formed to be longer than the lower end, and protrude below the lower surface of the diaphragm 72. The hob 71 is formed in a cylindrical shape having a straight hob hole 75 having a uniform inner diameter. The thin film portion 73 is formed concentrically with the hob portion 71 as shown in FIG.

The gasket 80 shown in FIG.
And a diaphragm portion 82 formed concentrically with the hob portion 81
And a thin film portion 83 formed on a part of the diaphragm portion 82
And an outer peripheral portion 84 formed outside the diaphragm portion 82. As shown in FIG. 12, the hob portion 81 has a straight hob hole 85 that projects substantially equally in the vertical direction of the diaphragm portion 82 and has a straight hob hole 85 having a uniform inner diameter. It is formed in a circular hole formed in a part of the diaphragm 82.

The gaskets 50, 60, 7 as described above
The method of molding 0, 80 (hereinafter simply referred to as gasket 50, etc.) is performed by injection molding in which a resin is poured from an injection gate into a space formed in a molding die. As for the conventional gasket 50 and the like, a method of molding a gasket using a molding die 90 shown in FIG. 13 has been proposed. The molding die 90 includes an upper die 90a and a lower die 90.
b, a cylindrical space portion 91 in which a hob portion is formed, a flat space portion 92 in which a diaphragm portion is formed, a bent space portion 93 in which an outer peripheral portion is formed, and a flat space portion 93. A thin film-shaped space portion 94 in which a thin film portion is formed is formed on the inner peripheral side of the disk-shaped space portion. Gasket 50
Is the bottom side of the cylindrical space portion 91, that is, the lower mold 9
The resin is poured into the molding die 90 from a pin point gate 96 which is opened adjacent to the base end of the core pin 95 of FIG.

In addition, a method has been proposed in which the gasket 50 and the like are molded using a molding die 100 of a gate system different from the molding die 90 shown in FIG. The molding die 100 has a cylindrical space portion 101 and a flat disk-shaped space portion 102 inside thereof, similarly to the molding die 90 described above.
, A bent space 103 and a thin film space 104 are formed. The gasket 50, etc.
The resin is poured from the side gate 105 opening at the end of the substrate 03 and molded.

The gasket 50 and the like also include a film gate or disc gate from the bottom of the space where the hob is formed, a single or multi-point pin gate from the space where the diaphragm is formed, and an outer periphery. There has been proposed a method in which a molding is performed by a molding die of various gate systems such as a submarine gate from a space where a portion is molded.

[0012]

As described above, gaskets constituting a cylindrical alkaline battery have been proposed in various shapes as described above, and a molding die and a molding corresponding to the shape of the gasket have been proposed. A plurality of gate systems that open to a mold have been proposed.

However, when the molten resin is poured into a molding die and injection molding is performed, the direction of the molten resin flowing is inconsistent if the shape of the gasket is improper, and if the mold and the gate system are inappropriate. The gasket is formed while the molten resin is not uniformly filled because the resin is not filled completely or the air in the mold is not sufficiently removed. If the gasket is molded with insufficient filling of the molten resin, molding defects such as a decrease in strength due to voids, sink marks and welds in the hob portion, and variations in weld and strength of the thin film portion occur.

[0014] The gasket is subjected to a shock at the time of inserting the current collecting rod into the hob part, a stress on the hob part after the current collecting rod is inserted, a long-term storage at room temperature and a severe temperature condition due to the gasket molding defect as described above. Cracks are more likely to occur in the hob part due to the storage of the steel. When the gasket cracks in the hob, the seal between the hob and the current collecting rod is broken, and the electrolyte in the battery crawls up between the hob and the current collecting rod to cause liquid leakage. was there. Further, the gasket has a problem that when a crack occurs in the hob portion, the thin film portion having a function as an explosion-proof safety valve is unevenly and unstablely split.

In the cylindrical alkaline battery, cracks in the hob portion of the gasket and uneven tearing of the thin film portion as described above have been major causes for lowering the liquid leakage resistance.

Further, the gasket has a void in the hob portion,
Weakness due to sink marks and welds, welds in thin film parts,
It has been technically very difficult to form such a shape that a problem-free level is maintained over a long period of time so as not to cause variations in strength.

Accordingly, the present invention provides a gasket having an explosion-proof safety valve which is excellent in crack resistance and stably cleaves in a certain state, a method of forming the gasket, and a cylinder having excellent liquid-proofing properties provided with the gasket. It is an object of the present invention to provide a type alkaline battery.

[0018]

A gasket according to the present invention that achieves the above-mentioned object is a gasket for sealing an opening of a battery case body of a cylindrical alkaline battery. A cylindrical portion in which a lower opening is wider than an upper opening and a hole into which a current collecting rod is inserted is formed, and a disk-shaped portion formed concentrically with the cylindrical portion on the outer peripheral side of the cylindrical portion, A thin-film portion formed concentrically with the cylindrical portion between the cylindrical portion and the disc-shaped portion and formed on the lower surface side of the disc-shaped portion, and a thin-film portion located on the outer peripheral side of the disc-shaped portion and formed to have a cross-sectional bend. And a portion formed continuously with the disk-shaped portion of the outer peripheral portion is formed to be thin.

Further, the gasket molding method according to the present invention is characterized in that the upper mold and the lower mold are combined to form a cylindrical space and a flat plate located on the outer peripheral side of the cylindrical space. And a curved space portion that is located on the outer peripheral side of the flat space portion and that is continuous with the flat space portion is formed narrower than the flat space portion. The cylindrical portion and the disc-shaped portion are formed in a chamfered or curved shape between the cylindrical space portion and the flat disk-shaped space, and a protrusion is formed by projecting from the upper mold to the lower mold. A thin film-shaped space is formed by this, and a plurality of pinpoint gates are provided in the lower mold at the bottom of the flat disk-shaped space, and the upper mold and the lower mold are connected to each other. Using a mold with an air vent formed above the parting line and cylindrical space Molding a gasket.

Further, in the cylindrical alkaline battery according to the present invention, the outer peripheral surface is formed in a tapered shape, the lower opening is wider than the upper opening, and a hole is formed in which the current collecting rod is inserted. A cylindrical portion, a disk-shaped portion formed concentrically with the cylindrical portion on the outer peripheral side of the cylindrical portion, and a lower surface side of the disk-shaped portion formed between the cylindrical portion and the disk-shaped portion concentrically with the cylindrical portion. And a peripheral portion which is located on the outer peripheral side of the disk-shaped portion and is formed with a bent cross section, and a portion formed continuously with the disk-shaped portion of the outer peripheral portion is thin. The opening of the battery case body is sealed by the gasket formed in the above.

According to the gasket of the present invention having the above-described structure, the method of forming the gasket, and the cylindrical alkaline battery, the molten resin flowing from the plurality of pinpoint gates provided on the bottom surface of the flat space is formed. The entire molding die is filled through the thin film-shaped space portion and the narrowly formed portion of the curved space portion, and the air vent in the molding die is sufficiently vented by the air vent provided in the molding die, A gasket excellent in crack resistance, in which the resin is uniformly and sufficiently filled, is formed. Further, according to the gasket according to the present invention, the method of molding the gasket, and the cylindrical alkaline battery, a portion formed continuously with the disk-shaped portion of the outer peripheral portion is formed to be thin and is torn when the battery internal pressure increases. An explosion-proof safety valve is formed in the gasket, which is structured and stably cleaves. Furthermore, according to the gasket according to the present invention, the method of molding the gasket, and the cylindrical alkaline battery, the opening of the battery case body is formed by the gasket having the explosion-proof safety valve that is excellent in crack resistance and stably cleaves as described above. Because of the sealing, the leakage resistance of the cylindrical alkaline battery is improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a gasket according to the present invention, a method of forming the gasket, and a cylindrical alkaline battery using the gasket will be described in detail with reference to the drawings. As shown in FIG. 1, the gasket 1 according to the present embodiment includes an outer peripheral portion 2 formed by bending a cross section toward the outer peripheral side, a thick hob portion 3 formed at the center,
It is composed of a flat disk-shaped diaphragm portion 4 formed between the outer peripheral portion 2 and the hob portion 3, and a thin film portion 5 formed between the hob portion 3 and the diaphragm portion 4. Gasket 1
Is formed by integrally molding the above-described parts.
As shown in FIGS. 2A and 2B, the gasket 1 has the above-described components formed in concentric rings.

As shown in FIG. 3, the gasket 1 has a positive electrode mixture 9, a separator 10 and a gelled negative electrode 11 built in a cylindrical alkaline battery 6 together with a washer 8 with a current collecting rod 7 inserted therein. Opening 1 of battery case body 12
2a is sealed. In the cylindrical alkaline battery 6, an opening 12 a sealed by the gasket 1 and the washer 8 is further closed by a negative electrode cover 13 and an insulating washer 14.

As shown in FIG. 3, the outer peripheral portion 2 is formed integrally with the positive electrode when the gasket 1 seals the opening 12a of the battery case body 12 and the negative electrode cover 13 is attached. Battery case body 12 and negative electrode cover 13
End 2a is interposed between the battery case body 12 and the battery case body 12 and the negative electrode cover 13 are insulated.

The outer peripheral portion 2 is formed such that a bent portion 2b formed continuously with the diaphragm portion 4 is thinner than the diaphragm portion 4. The bent portion 2b is formed to have a thickness of 0.20 mm to 0.35 mm, and has a cylindrical alkaline battery 6.
The gasket 1 has a function as an explosion-proof safety valve that is opened when gas is generated in the battery and the gasket 1 is stressed due to an increase in battery internal pressure. If the bent portion 2b is formed to have a thickness of less than 0.20 mm, the flow path of the molten resin to the outer peripheral portion 2 at the time of molding the gasket 1 becomes narrow, and the flow of the molten resin is hindered. It becomes weak, and the cleavage pressure is remarkably reduced to facilitate cleavage. The bent portion 2b has a thickness of 0.1 mm.
If it is formed to exceed 35 mm, the flow of the molten resin to the outer peripheral portion 2 is widened when the gasket 1 is formed, and the flow to the outer peripheral portion 2 is prioritized, so that the flow of the molten resin to the hob portion 3 is obstructed. As a result, molding defects such as voids, sink marks, welds, etc. occur in the hob portion 3, and the strength is increased, making it difficult to split.

The hob 3 is formed in a cylindrical shape having a hob hole 15 at the center. The hob portion 3 is formed such that the lower portion of the outer peripheral surface thereof is formed in a tapered shape, and the lower portion of the inner peripheral surface has the lower opening portion 15b similarly to the lower portion of the outer peripheral surface.
It is formed in a tapered shape that opens wider than it. The hob portion 3 is formed such that the lower portion of the outer peripheral surface and the lower portion of the inner peripheral surface are each formed in a tapered shape, so that the hob portion 3 when the current collecting rod 7 is inserted from the upper opening 15a toward the lower opening 15b. Impact on the lower part of the inner peripheral surface of the current collector and the current collector 7 after the current collector 7 is inserted
The stress on the lower portion of the inner peripheral surface of the hob portion 3 is alleviated to suppress the occurrence of cracks. The gasket 1 suppresses the occurrence of cracks in the hob portion 3, so that the seal between the hob portion 3 and the current collecting rod 7 is not broken, and the leakage of the cylindrical alkaline battery 6 due to the creeping up of the electrolyte or the like is suppressed. I do.
In the present embodiment, the lower portion of the inner peripheral surface of the hob portion 3 is formed in a tapered shape, but the present invention is not limited to such a configuration. The lower portion of the inner peripheral surface of the hob portion 3 has an inner periphery in order to create an escape area for the impact on the lower portion of the inner peripheral surface when the current collecting rod 7 is inserted and the stress on the lower portion of the inner peripheral surface due to the current collecting rod 7 after the current collecting rod 7 is inserted. It may be formed as long as it is wider than the upper part of the surface. For example, it may be formed in a convex step shape.

The hob 3 is provided with the lower opening 1 of the hob hole 15.
The lower end of the opening 5 b projects from the lower surface of the diaphragm 4. The hob 3 is formed such that its lower end protrudes from the lower surface of the diaphragm 4, so that the contact area between the gasket 1 and the current collecting rod 7 can be increased. For this reason, the gasket 1 suppresses the leakage of the cylindrical alkaline battery 6 because the distance in which the electrolyte or the like in the battery case body 12 crawls between the gasket 1 and the current collecting rod 7 increases.

The hob hole 3 has an inner diameter in the range of 80% to 90% of the outer diameter of the current collecting rod 7.
5 are formed. If the inner diameter of the hob 3 is set to 80% or less of the outer diameter of the current collector 7, the impact and stress applied to the hob 3 when the current collector 7 is inserted increases, so that the hob 3 tends to crack. The seal with the current collecting rod 7 is broken, and liquid leakage occurs. When the inner diameter of the hob 3 is 90% or more of the outer diameter of the current collecting rod 7, the adhesion between the hob 3 and the current collecting rod 7 is reduced, and the leakage due to the creeping up of the electrolyte or the like is suppressed. become unable.

When gas is generated in the cylindrical alkaline battery 6 due to misuse or the like and the internal pressure of the battery rises, the diaphragm portion 4 receives stress due to the internal pressure. The thickness of the diaphragm portion 4 is 0.2 mm to 0.6 mm thicker than that of the thin film portion 5.
mm thick. The diaphragm portion 4 is formed to be 0.2 mm to 0.6 mm thicker than the thickness of the thin film portion 5 so that the residual stress of the injection gate during injection molding is reduced and the strength difference between the bent portion 2b and the thin film portion 5 is reduced. As a result, the breaking pressure of the bent portion 2b is stabilized. Diaphragm part 4
Is not formed 0.2 mm or more thicker than the thin film portion 5,
The residual stress of the injection gate at the time of injection molding becomes large, cracks easily occur due to embrittlement of the gasket 1 under high-temperature storage conditions and long-term normal-temperature storage conditions, and the bent portion 2
The cleavage pressure of b is lowered and cleavage becomes unstable. Further, when the diaphragm portion 4 is formed to have a thickness exceeding 0.6 mm than the thin film portion 5, the strength of the bent portion 2b becomes too strong, so that the diaphragm portion 4 is hardly split.

As shown in FIGS. 2A and 2B, the thin film portion 5 is formed concentrically with the hob portion 3 between the hob portion 3 and the diaphragm portion 4, that is, on the outer peripheral side of the hob portion 3. You. The thin film part 5 is formed on the lower surface side of the diaphragm part 4, as shown in FIG.

As shown in FIG. 4A, the outer peripheral side, that is, the boundary portion with the diaphragm portion 4 and the inner peripheral side, that is, the boundary portion with the hob portion 3, are cut into a chamfered shape as shown in FIG. The inclined surface 16 is formed. The slope 16
It is preferable that the chamfer length C is formed in the range of 0.01 mm to 0.20 mm. In addition, the thin film portion 5
As shown in FIG. 4B, the inner peripheral side, that is, the boundary portion with the hob portion 3 may have a curved surface 17 instead of the inclined surface 16 as described above. The curved surface 17 preferably has a radius of curvature R in the range of 0.05 mm to 0.30 mm. Since the thickness of the thin film portion 5 at the boundary between the hob 3 and the diaphragm 4 increases due to the formation of the inclined surface 16 or the curved surface 17, the strength of the thin film 5 increases. It does not break before the bent portion 2b.

The above-described gasket 1 is formed by filling a molding die 18 shown in FIG. 5 with a resin.
The molding die 18 forms an integral space therein by combining the upper die 18a and the lower die 18b. The molding die 18 includes a cylindrical space 19 in which the hob 3 is formed, a flat space 20 in which the diaphragm 4 is formed, and a bent space 21 in which the outer periphery 2 is formed. , And a thin film-shaped space portion 22 in which the thin film portion 5 is formed.

In the molding die 18, a projecting portion 23 is formed on a portion of the upper die 18a where the thin film space 22 is formed.
8b. The projecting portion 23 has a cylindrical space so that an inclined surface 16 or a curved surface 17 is formed at a connection portion between the thin film portion 5 and the hob portion 3 and a connection portion with the diaphragm portion 4 when the gasket 1 is formed. The portion 19 side and the flat disk space portion 20 side are formed in a chamfered shape or a curved shape.

The molding die 18 is provided with a plurality of pinpoint gates 24 on the bottom side of the flat space 20 of the lower die 18b. The molding die 18 has a thin bent portion 2b.
Is formed so that the interval between the portions continuous with the flat space portion 20 of the bent space portion 21 is formed to form
The flow of the molten resin from the pinpoint gate 24 to the outer peripheral portion 2 and the hob portion 3 during injection molding is made uniform and smooth,
Molding defects of the gasket 1 such as voids, sink marks and welds are reduced.

The molding die 18 is provided with an air vent between the core pin 25 disposed at the portion where the hob hole 15 is formed and the upper die 18a and the parting line between the upper die 18a and the lower die 18b. 26 are provided. When the molten resin is poured into the molding die 18 from the pinpoint gate 24, the air in the die easily escapes from the end face of the outer peripheral portion 2 and the upper portion of the hob portion 3 from the air vent 26. The flow of the molten resin to the portion 3 is made smooth, and molding defects such as voids, sink marks, and welds are reduced.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A gasket will be specifically described based on the results of various tests performed on the cylindrical alkaline batteries of the test samples 1 to 13 shown below. In addition, as for the test article 1 to the test article 13, a gasket molded into the same shape by the same molding method as the gasket 1 according to the above-described embodiment is used for shapes and molding methods other than the conditions particularly shown.

First, a test was performed on the test articles 1 to 5 to determine whether or not cracks were generated due to the impact of the insertion of the current collector rod, and a measurement test was performed on the breaking pressure of the bent portion. In the insertion test of the current collector rod, the gasket was dried under a dry condition at a temperature of 100 ° C. for 24 hours, and then 160 g with respect to the inner diameter of the hob.
% Of the current collecting rod is inserted, and the occurrence of cracks in the hob portion is observed by a microscope with a magnification of 20 times. In the insertion test of the current collector rod, the above-described operation was performed for each of the one type of the test piece, and each of the test pieces was checked for the number of cracks generated. The bending pressure was measured using a dedicated hydraulic measuring device for each of the 50 samples, and the average value and the standard deviation of the bending pressure at each bending point, that is, the bending The variation in pressure at which the bend was split was calculated. Table 1 shows the results. In addition,
The configurations of the cylindrical alkaline batteries according to the test items 1 to 5 used in the test are as shown below.

The test sample 1 is the cylindrical alkaline battery 1 according to the above-described embodiment, in which the thickness of the bent portion of the gasket is 0.25 mm. In addition, the thicknesses of the bent portions of the gaskets of the test pieces 2 to 5 are 0.20 mm, 0.35 mm,
It is a cylindrical alkaline battery formed to 0.40 mm and 0.15 mm.

[0039]

[Table 1]

As shown in Table 1, test items 1 to 3
It was confirmed that cracks did not occur and that there was little variation in the cleavage pressure of the bent portion. On the other hand, it was confirmed that the test piece 4 had cracks and the bent portion did not split, and that the test piece 5 had an extremely low cleavage pressure average value. From this result, it can be determined that a cylindrical alkaline battery in which the bent portion of the gasket is formed with a thickness of 0.20 mm to 0.35 mm is preferable.

Next, the test for the presence or absence of cracks due to the impact of the current collector rod insertion and the measurement test for the breaking pressure of the bent portion were performed on the test sample 1, the test sample 6 and the test sample 7 in the manner described above. went. Table 2 shows the results. In addition,
The configurations of the cylindrical alkaline batteries according to the test pieces 6 and 7 used in the test are as shown below.

The specimen 6 is a specimen in which the thickness of the diaphragm of the specimen 1 is 0.15 mm thicker than that of the thin film part.
In the test sample 7, the diaphragm portion of the test sample 1 is 0.65 mm thicker than the thin film portion. In the test sample 1, the thickness of the diaphragm was 0.2 mm larger than that of the thin film.
It is formed to be 0.6 mm thick.

[0043]

[Table 2]

As shown in Table 2, it was confirmed that no crack was generated in the test sample 1 and that there was little variation in the breaking pressure of the bent portion. In contrast, test sample 6
Has cracks, and it was confirmed that the bent portion of the test sample 7 did not split. From these results, it can be determined that a cylindrical alkaline battery in which the diaphragm portion of the gasket is formed to be 0.2 mm to 0.6 mm thicker than the thin film portion is preferable.

Further, the test article 1 and the test article 8 were subjected to a test for the occurrence of liquid leakage and the occurrence of cracks under certain storage conditions. The test for the presence or absence of liquid leakage was performed after storage for 1 year and 2 years under the storage conditions of normal temperature and normal humidity after battery production, and 40 years at the storage condition of 75 ° C. and 50% humidity.
Day, after storage for 80 days and 120 days, to determine the presence or absence of liquid leakage,
The determination of liquid leakage was made by visual observation, the battery that had leaked was disassembled, and the presence or absence of cracks in the gasket was observed with a 20-power microscope. In addition, the test for the presence or absence of occurrence of liquid leakage was performed for each of the 100 types of test samples. Table 3 shows the results. In addition, the test sample 8 has a chamfered outer peripheral side of the thin film portion of the gasket, and the test sample 1 has a chamfered outer peripheral side of the thin film portion of the gasket.

[0046]

[Table 3]

As shown in Table 3, it was confirmed that the test article 1 did not cause liquid leakage and cracks under each condition. On the other hand, it was confirmed that the test article 8 had a liquid leak after storage for 120 days and also had a crack. From this result, it can be determined that a cylindrical alkaline battery in which the outer peripheral side of the thin film portion of the gasket is chamfered is preferable.

Finally, test sample 1 and test samples 9 to 1
The test for No. 3 was performed by the method described above for the presence or absence of cracks due to the impact of the insertion of the current collector rod. Table 4 shows the results. In addition, the test sample 1 and the test samples 9 to 13
Are those using the above-mentioned molding dies 18 in the molding dies for molding the gasket, those using the molding dies 18 without the air vents provided on the parting line, and those provided with the air vents on the upper side of the hob. One using a molding die 18 not provided, one using a molding die provided with a ring gate from the top of the hob part, one using a molding die provided with a pinpoint gate from the bottom of the hob part And a molding die provided with a side gate from the outer peripheral side surface.

[0049]

[Table 4]

As shown in Table 4, the test sample 1 was confirmed to have no cracks. In contrast, test sample 9
It was confirmed that cracks occurred in each of the test pieces 13 to 13. From these results, the cylindrical alkaline battery used a molding die in which the gasket was provided with a parting line of the molding die and an air vent on the upper part of the hob, and the emission gate was provided with a plurality of pinpoint gates from the bottom of the diaphragm. It can be determined that what is performed is preferable.

[0051]

As described above in detail, according to the cylindrical alkaline battery and the method for manufacturing the cylindrical alkaline battery according to the present invention, the crack resistance is improved by the molding die in which the molten resin flows uniformly and smoothly. Since a gasket having excellent heat resistance is formed, it is possible to suppress the occurrence of molding defects such as a decrease in strength due to voids, sink marks and welds in the hob portion, and variations in strength. Further, according to the cylindrical alkaline battery and the method for manufacturing the cylindrical alkaline battery according to the present invention, the bent portion formed in the gasket is stably split by receiving the internal pressure of the battery. Therefore, the cylindrical alkaline battery and the method for manufacturing the cylindrical alkaline battery according to the present invention have an explosion-proof safety valve in which the gasket for sealing the battery case body is excellent in crack resistance and stably cleaves. Improved liquid leakage resistance.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a gasket.

FIG. 2A is a plan view of a gasket, and FIG.
Is a bottom view of the gasket.

FIG. 3 is a longitudinal sectional view of a cylindrical alkaline battery.

4A is an enlarged cross-sectional view of a main part of a gasket in which a boundary between a hob and a thin film and a boundary between a diaphragm and a thin film are chamfered, and FIG. FIG. 4 is an enlarged cross-sectional view of a main part of a gasket in which a boundary between a thin film portion and a diaphragm and a boundary between a thin film portion and a diaphragm are curved.

FIG. 5 is a longitudinal sectional view of a molding die for molding a gasket.

FIG. 6 is a longitudinal sectional view of a first conventional gasket.

FIG. 7 is a longitudinal sectional view of a second conventional gasket.

FIG. 8 is a longitudinal sectional view of a third conventional gasket.

FIG. 9 is a longitudinal sectional view of a fourth conventional gasket.

FIG. 10 is a bottom view of the first and second conventional gaskets.

FIG. 11 is a bottom view of a third conventional gasket.

FIG. 12 is a bottom view of a fourth conventional gasket.

FIG. 13 is a longitudinal sectional view of a first molding die for molding a gasket of a conventional example.

FIG. 14 is a longitudinal sectional view of a second molding die for molding a gasket of a conventional example.

[Description of sign]

DESCRIPTION OF SYMBOLS 1 Gasket, 2 outer peripheral part, 2b bent part, 3 hob part, 4 diaphragm part, 5 thin film part, 6 cylindrical alkaline battery, 7 current collector rod, 12 battery case body, 15
Hob hole, 16 inclined surface, 17 curved surface, 18 molding die, 18a upper die, 18b lower die, 19 cylindrical space, 20 flat space, 21 bent space, 2
2 Thin film space, 23 Projection, 24 Pinpoint gate, 26 Air vent

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideaki Tokugawa 1-1, Shimosugishita, Takakura, Hiwada-cho, Koriyama-shi, Fukushima Prefecture Inside Sony Energy Tech Co., Ltd. (72) Inventor Kazuhiro Hashimoto Hiwa, Koriyama-shi, Fukushima Prefecture (1) Sony Energy Tech Co., Ltd. (72) Inventor Akihiro Sugawara 1) Shimosugishita, Takakura, Hiwada-cho, Koriyama-shi, Fukushima Pref. Sony Energy Tech Co., Ltd. Reference) 5H011 AA09 AA13 AA17 FF03 GG02 JJ02 JJ29 KK01 KK03

Claims (6)

[Claims] 1. A gasket for sealing an opening of a battery case body of a cylindrical alkaline battery, wherein an outer peripheral surface is formed in a tapered shape, a lower opening is opened wider than an upper opening, and a current collector rod is provided. A cylindrical part in which a hole to be inserted is formed; a disk-shaped part formed concentrically with the cylindrical part on the outer peripheral side of the cylindrical part; and a cylindrical part concentric between the cylindrical part and the disk-shaped part A thin-film portion formed in an annular shape and formed on the lower surface side of the disc-shaped portion; and an outer peripheral portion located on the outer periphery side of the disc-shaped portion and formed to bend in cross section. A gasket, characterized in that a portion formed continuously with the disc-shaped portion of the portion is formed to be thin and is torn by an increase in internal pressure in the battery case body. 2. The gasket according to claim 1, wherein a portion formed continuously with the disk-shaped portion of the outer peripheral portion has a thickness of 0.20 mm to 0.35 mm. Gasket. 3. The gasket according to claim 1, wherein the disk-shaped portion is formed to be 0.2 mm to 0.6 mm thicker than the thin film portion. 4. The gasket according to claim 1, wherein a boundary portion between the thin film portion and the cylindrical portion and a boundary portion between the thin film portion and the disk-shaped portion are formed in a chamfered shape or a curved shape. The gasket according to claim 1. 5. A method of forming a gasket by filling a resin into a molding die having a space formed therein by combining an upper die and a lower die, and forming a gasket. The lower mold is combined with a cylindrical space portion, a flat space portion located on the outer peripheral side of the cylindrical space portion, and a flat space portion located on the outer peripheral side of the flat space portion. A bent space portion is formed in which a portion continuous with the flat space portion is formed narrower than the flat space portion, and the cylindrical space portion and the flat space portion are formed. Between the cylindrical space portion side and the disk-shaped space portion side, a protrusion formed in a chamfered shape or a curved surface is formed by projecting from the upper mold to the lower mold, thereby forming a thin film-shaped space portion. And the lower mold is opened at the bottom of the flat space. A plurality of pinpoint gates are provided, and a gasket is formed by using a molding die having an upper vent and a lower die with a parting line and an air vent formed above the cylindrical space. Forming a gasket. 6. A cylindrical portion having an outer peripheral surface formed in a tapered shape, a lower opening portion being wider than an upper opening portion, and a hole portion into which a current collecting rod is inserted being formed, and an outer periphery of the cylindrical portion. A disc-shaped part formed concentrically with the cylindrical part on the side,
A thin-film portion formed concentrically with the cylindrical portion between the cylindrical portion and the disc-shaped portion and formed on the lower surface side of the disc-shaped portion, and located on the outer peripheral side of the disc-shaped portion and bent in cross section. The opening of the battery case body is sealed with a gasket having a portion formed continuously with the disk-shaped portion of the outer peripheral portion, the portion being formed thin. Characteristic cylindrical alkaline battery.