JP2014135242A - Gasket for alkaline battery and alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gasket for an alkaline battery capable of surely preventing various kinds of liquid leakage due to different causes.SOLUTION: There is provided a gasket 20a in an alkaline battery in which an annular positive electrode mixture, a bottomed cylindrical separator, and a negative electrode gel are stored in a bottomed cylindrical battery can, and a negative electrode terminal board is attached to an opening of the battery can by being fitted therewith through the gasket 20a for sealing. The gasket is made of an integrally-molded resin material, and includes a disc-like partition wall part 23, an outer peripheral part 24 in an upwardly standing condition from the periphery of the partition wall part, and a boss part 21 installed in a protruding condition in a hollow cylindrical shape in a vertical direction on the center of the disc-like partition wall part. The boss part is composed of an outer cylinder part 26a and an inner cylinder part 27a which are arranged coaxially. The inner cylinder part is made of a first resin material. The outer cylinder part of the boss part, the partition wall part and the outer peripheral part continuous with the outer cylinder part are formed of a second resin material having a different physical property from the first resin material.

Description

  The present invention relates to a technique for improving a sealing gasket constituting an alkaline battery.

  FIG. 1 shows the structure of a general LR6 type cylindrical alkaline battery 1, and FIG. 1 shows a longitudinal sectional view when the extending direction of the cylindrical shaft 100 is the vertical (vertical) direction. . As shown in the figure, the alkaline battery 1 includes a bottomed cylindrical metal battery can 2, a positive electrode mixture 3 formed in an annular shape, and a bottomed cylindrical separator 4 disposed inside the positive electrode mixture 3. The negative electrode gel 5 containing zinc alloy and filled inside the separator 4, the metal negative electrode current collector 6 inserted in the negative electrode gel 5, the dish-shaped metal negative electrode terminal plate 7, and the sealing gasket ( Hereinafter, it is constituted by a gasket 20 or the like. In this structure, the positive electrode mixture 3, the separator 4, and the negative electrode gel 5 form the power generation element of the alkaline battery 1 in the presence of the electrolytic solution. In the following, the vertical direction is defined with the bottom side of the battery can 2 as the lower side.

  The battery can 2 also serves as a battery case, and also serves as a positive electrode current collector by being in direct contact with the positive electrode mixture 3. A positive electrode terminal 8 is formed on the bottom surface of the battery can 2. The dish-shaped negative electrode terminal plate 7 is a dish shape with a flange-like edge, and when the positive electrode terminal 8 is set downward, the dish-shaped negative electrode terminal plate 7 is caulked through the gasket 7 with the dish being turned down. .

  The rod-shaped negative electrode current collector 6 inserted in the negative electrode gel 5 is fixed upright by welding its upper end to the lower surface of the dish-shaped negative electrode terminal plate 7. The negative electrode terminal plate 7, the negative electrode current collector 6, and the gasket 20 are combined in advance as a sealing body, and the gasket 20 is between the opening edge of the battery can 2 and the flange-shaped edge of the negative electrode terminal plate 7. The battery can 2 is sealed. In addition, an exterior label 9 made of a heat shrink film is attached around the battery can 2.

  FIG. 2 is a view showing the structure of the gasket 20, and here shows the shape before being crimped to the opening of the battery can 2, and FIG. 2 (A) is a plan view when viewed from above. In this figure, each part (21-23) of the gasket 20 is shown by different hatching. (B) is a longitudinal cross-sectional view and corresponds to the cross section taken along the line aa in (A). The gasket 20 has a cup shape around which a wall surface (hereinafter referred to as an outer peripheral portion) 24 erected upward around the disk. The center of the disk includes a hollow portion (boss hole) 22 into which the negative electrode current collector 6 is press-fitted. A cylindrical boss portion 21 is formed. Concentric concavities and convexities are formed in a film-like portion (hereinafter referred to as a partition wall portion) 23 extending from the outer periphery of the boss portion 21 to the periphery of the disk, and the storage space for the power generation element in the battery can 2 is sealed by the partition wall portion 23. The inside of the battery can 2 is partitioned up and down. The negative electrode terminal plate 7, the negative electrode current collector 6, and the gasket 20 are combined in advance as a sealing body, and the outer peripheral portion 24 of the gasket 20 is connected to the opening edge of the battery can 2 and the edge of the negative electrode terminal plate 7. The battery can 2 is hermetically sealed by being caulked while being sandwiched between the two.

  Further, a thin portion 25 such as a groove is formed on a part of the surface of the partition wall portion 23 of the gasket 20, and this thin portion 25 is broken in advance when the pressure in the battery can 2 is abnormally increased. Finally, it functions as an explosion-proof safety mechanism for releasing the gas causing the internal pressure to the atmosphere through the exhaust hole 10 (see FIG. 1) provided in the negative electrode terminal plate 7.

  Incidentally, the gasket 20 is generally an integrally molded product of polyamide resin, so-called nylon resin, and is formed by injection molding. 6-6 nylon resin (hereinafter, nylon 6-6) is often used. Further, in Patent Document 1 below, polyhexamethylene dodecamide resin, so-called 6-12 nylon resin (hereinafter, nylon 6) is used in order to further improve the storage stability and leakage resistance of alkaline batteries under high temperature and high humidity. -12) is described for gaskets. Further, Patent Document 2 below describes a technique using a regenerated material of 6-12 nylon resin as a resin material for injection molding in order to prevent cracking of a boss portion into which a negative electrode current collector is press-fitted.

JP-A-11-250875 JP 2007-80574 A

  When a nylon resin gasket is used, when the current collector is press-fitted into the central boss portion of the gasket during the alkaline battery manufacturing process, the boss portion may be cracked. And the problem that a battery leaks by the crack arises. In the invention described in Patent Document 2, the regenerated material of 6-12 nylon resin is used as the molding resin for the gasket, thereby successfully preventing the boss portion from cracking in the conventional 6-12 nylon resin. .

  However, the cause of leakage is not only the cracking of the boss. For example, due to moisture permeability in the resin material of the gasket, moisture that has entered the battery through the gasket reacts with the chemical substance in the battery to generate gas, and the above explosion-proof safety mechanism is activated to cause leakage. Sometimes it is. In some cases, the resin material of the gasket absorbs moisture and becomes brittle, resulting in cracks that lead to leakage. Even if the gasket is not cracked or cracked, leakage may occur due to the creeping-up (creep) phenomenon of the electrolyte at the interface between the battery can and the gasket or the interface between the negative electrode current collector and the boss.

  Accordingly, an object of the present invention is to provide a gasket for an alkaline battery that can surely prevent a wide variety of liquid leaks having different causes.

In order to achieve the above object, the present invention provides a bottomed cylindrical battery can with a bottom at the bottom, a circular positive electrode mixture, and a bottomed cylindrical separator disposed inside the positive electrode mixture. The negative electrode gel disposed inside the separator is housed, and the gasket in the alkaline battery in which a negative electrode terminal plate is fitted to the opening of the battery can via a gasket for sealing,
The gasket is made of an integrally molded resin material, and has a disk-shaped partition wall, an outer peripheral portion standing upward from the periphery of the partition wall, and a hollow cylinder in the vertical direction at the center of the disk-shaped partition wall A boss part protruding in a shape,
The boss part is a double cylinder composed of an outer cylinder part and an inner cylinder part arranged coaxially,
The inner cylinder portion is formed of a first resin material;
The outer cylinder part of the boss part, the partition part continuous to the outer cylinder part, and the outer peripheral part are formed of a second resin material having different physical properties from the first resin material.
It is set as the gasket for alkaline batteries characterized by this.

The first resin material has a tensile strength of 65 MPa or more and a Rockwell hardness of R100 or more and R120 or less,
The second resin material has an equilibrium water absorption of 5.00% or less and a Rockwell hardness of R100 or more and R120 or less.
The alkaline battery gasket is preferable.

  In the above alkaline battery gasket, the ratio φi / φo × 100 (%) between the outer diameter φo of the outer cylinder portion of the boss portion and the outer diameter φi of the inner cylinder portion may be 50% or more and 90% or less.

  Also, in the bottomed cylindrical battery can, an annular positive electrode mixture, a bottomed cylindrical separator arranged inside the positive electrode mixture, and a negative electrode gel arranged inside the separator are stored. In addition, an alkaline battery in which a negative electrode terminal plate is fitted into the opening of the battery can via any one of the alkaline battery gaskets is also included in the scope of the present invention.

  According to the gasket for an alkaline battery of the present invention, it is possible to reliably prevent liquid leakage generated due to various causes.

It is a figure which shows the structure of a general alkaline battery. It is a figure which shows the structure of the conventional gasket integrated in the said general alkaline battery. It is a figure which shows the structure of the gasket which concerns on one Embodiment of this invention. It is a structural diagram of an alkaline battery incorporating a gasket according to an embodiment of the present invention. It is a figure for demonstrating the manufacturing method of the gasket which concerns on one Embodiment of the said invention. It is a figure which shows the example of the structure of the gasket formed with two types of resin from which a physical property differs. It is a figure for demonstrating the size of each site | part of the boss | hub part in the gasket which concerns on one Embodiment of the said invention.

=== Embodiment ==
The gasket for alkaline batteries according to an embodiment of the present invention has the same external shape as that incorporated in the general alkaline battery 1 shown in FIG. However, in order to cope with various causes of liquid leakage, different resin materials are used depending on the portion of the gasket.

  FIG. 3 is a longitudinal sectional view showing the structure of an alkaline battery gasket (hereinafter referred to as gasket) 20a according to an embodiment of the present invention. FIG. 4 shows a longitudinal sectional view of an alkaline battery 1a incorporating the gasket 20a. In the gasket 20 a according to the embodiment of the present invention, when the liquid leakage caused by the crack of the boss portion 21 presses the negative electrode current collector 6 into the boss hole 22 in the boss portion 21, the current collector 6 becomes the boss portion 21. The inner surface of the boss portion 21 is made of a resin material that can withstand the stress. Thereby, the cylindrical boss portion 21 is formed in a double cylindrical shape including an inner cylinder portion 27a on the inner peripheral side concentric with the cylindrical shaft 110 and an outer cylinder portion 26a on the outer periphery side.

  In this gasket 20a, leakage due to moisture permeation and absorption in the partition wall 23 is dealt with by configuring the partition wall 23 with a resin material having a low moisture absorption rate (equilibrium water absorption rate). Furthermore, the leakage due to creep phenomenon is plastically deformed by the pressure when caulking into the opening of the battery can 2 while having flexibility to follow the surface shape of the battery can 2 and the negative electrode current collector 6 in contact with the gasket 20a. Hardness that does not occur is also required.

  In the gasket 20a shown in FIG. 3, the inner cylinder portion 27a of the boss portion and the other portions (23, 24, 26a) are formed of different resin materials, and the joint surfaces between the different resin materials are well known. By using a two-color molding technique or the like, the gasket 20a itself is integrated into the battery can 2 as an integral part. Moreover, the outer cylinder part 26a has a shape in which a part of the bottom surface of the bottomed cylinder is opened, and the inner cylinder part 27a does not extend to the lower end 28 of the boss part. The opening diameter φ2 at the bottom surface of the outer cylinder portion 26a is larger than the inner diameter φ1 of the boss hole 22, whereby the peripheral edge of the lower surface 29 of the inner cylinder portion 27a is covered with the bottom surface of the outer cylinder portion 26a. Only the vicinity of the center of the lower surface of 27 a is exposed downward from the lower end 28 of the boss portion 21.

=== Resin material of gasket ===
In the gasket 20 a shown in FIG. 3, the resin material of the inner cylinder portion 27 a needs to have physical properties that do not cause cracking when the negative electrode current collector 6 is press-fitted, and other parts (23, 24, 26 a ) Resin material is required to have physical properties such that liquid leakage due to moisture absorption does not occur. Both resin materials are required to have physical properties that do not cause a creep phenomenon.

<First resin material>
First, the resin material used for the inner cylinder part 27a is examined. As described above, the crack of the boss portion 21 is caused by press-fitting the negative electrode current collector 6 into the boss portion 21 in the manufacturing process of the alkaline battery 1a. That is, the negative electrode current collector 6 is inserted so as to expand the inner diameter of the boss portion 21, and the stress at the time of insertion causes a crack. Therefore, the resin material (hereinafter referred to as the first resin material) used for the inner cylinder portion 27a needs to have a tensile strength that does not cause cracking when the negative electrode current collector 6 is press-fitted. Therefore, the conventional gasket 20 shown in FIG. 2 instead of FIG. 3 was manufactured using various resin materials for the purpose of confirming only the presence or absence of leakage due to the crack of the boss portion 21. And the conventional alkaline battery 1 shown in FIG. 1 was produced as a sample using various gaskets 20 having different resin materials. In addition, 40 individuals were prepared for each sample. Each individual is then subjected to a high-temperature storage test (90 ° C / Dry storage test) that is stored in a dry atmosphere at a temperature of 90 ° C for 40 days in accordance with JIS standards. The presence or absence was investigated.

Table 1 shows the resin material, tensile strength, and high-temperature storage test results for each sample.

  As shown in Table 1, in Samples 1 to 7 using the gasket 20 made of a resin material having a tensile strength of 60 MPa or less, there were one or more individuals in which liquid leakage occurred. In Samples 8 to 12 using the gasket 20 made of a resin material having a tensile strength of 65 MPa or more, there was no solid that had leaked. Therefore, by forming the inner cylindrical portion 27a with a resin material having a tensile strength of 65 MPa or more, it is possible to reliably prevent cracking due to the press-fitting of the negative electrode current collector 6.

<Second resin material>
Next, in order to prevent leakage due to the water absorption and moisture permeability of the resin material, the resin material (hereinafter referred to as the second resin) in the portion (23, 24, 26a) other than the inner cylindrical portion 27a of the boss portion 21 is used. We investigated the physical properties required for the material. Specifically, the conventional gasket 20 shown in FIG. 2 was prepared using various resin materials having different equilibrium water absorption rates, and the alkaline battery 1 shown in FIG. Again, 40 solids were produced for each sample. Then, all the individuals were tested for storage for 60 days in an environment of 90% relative humidity (90% RH) at a temperature of 60 ° C., which is also based on JIS standards. Of these, the ratio (%) of the samples that led to leakage was examined.

Table 2 shows the resin material, equilibrium water absorption, and 60 ° C. 90% R.D. for each sample. H. The results of the storage test are shown.

  As shown in Table 2, samples 21 to 25 incorporating the gasket 20 made of a resin material having an equilibrium water absorption rate of 6% or more include leaked individuals, and the number of leaked individuals is the equilibrium water absorption The higher the rate, the more results. And in samples 13-20 whose equilibrium water absorption is 5% or less, no leakage occurred in all individuals. In addition, 60 degreeC90% R. H. Individuals that have leaked in the storage test may have leaked due to the normal operation of the explosion-proof safety mechanism due to an increase in internal pressure due to gas generated by moisture that has entered the alkaline battery 1, or the resin material itself of the gasket 20. However, the gasket 20 is brittle due to moisture absorption, and the gasket 20 is broken and leaks at a pressure lower than the normal operating pressure of the explosion-proof safety mechanism. In any case, if a resin material having an equilibrium water absorption of 5% or less is used for the flat surface portion of the gasket, the water that has entered through the partition wall 23 and the leakage due to the embrittlement of the resin material due to the absorbed water Can be reliably prevented.

<Rockwell hardness of the first and second resin materials>
The creep phenomenon in an alkaline battery occurs due to a decrease in adhesion at the contact surface when the gasket comes into contact with another member. That is, if the resin material is too hard, the fine surface shape of the other member cannot be followed and the adhesion is lowered. On the other hand, if the resin material is too soft, it is plastically deformed when compressed by caulking, cannot be restored from the compressed state, and cannot maintain adhesion with other members.

  Therefore, the conventional gasket 20 shown in FIG. 2 was manufactured using various resin materials having different Rockwell hardness, and the alkaline battery 1 was manufactured using these gaskets 20. Then, using the alkaline battery 1 using the same gasket 20 as a sample, 40 solids were prepared for each sample, and all the solids were subjected to a temperature of 60 ° C. and 50% R.D. H. The test which preserve | saves for 100 days in this environment was done, and the ratio (%) of the sample which resulted in the liquid leakage among 40 individuals of each sample was investigated.

  In addition, as for the type of liquid leakage, the adhesion between the outer peripheral portion 24 of the gasket 20 and the inner surface of the battery can 2 (positive electrode creep) and the negative electrode current collector 6 at the boss portion 21 of the gasket 20. Due to (negative electrode creep). As for the positive electrode creep, the occurrence of liquid leakage was detected by a so-called “color loss” phenomenon in which the leaked electrolyte solution denatures the ink used for decoration of the exterior label 9. As for the negative electrode creep, phenolphthalein was applied to the outside of the negative electrode terminal plate 7, and the occurrence of leakage was detected by discoloring the phenolphthalein with an alkaline electrolyte.

Table 3 shows the resin material, Rockwell hardness, and 60 ° C. 50% R.D. for each sample. H. The results of the storage test are shown.

  As shown in Table 3, in Sample 31 with Rockwell hardness R130, the resin material of the gasket 20 was too hard, so both positive and negative creep occurred. In Samples 26 and 27 having a Rockwell hardness of R90 or less, the resin material of the gasket 20 was too soft, so that both positive electrode creep and negative electrode creep occurred. And in samples 28-30 using the gasket whose Rockwell hardness is in the range of R100-R120, no liquid leakage due to the creep phenomenon occurred. Therefore, if the Rockwell hardness of the resin material of the inner cylinder portion and the flat portion of the gasket is both R100 or more and R120 or less, it is possible to reliably prevent leakage due to the creep phenomenon.

=== Structure of gasket ===
As described above, by using different resin materials for the inner cylindrical portion 27a and the other parts (23, 24, 26a), it is possible to reliably prevent various forms of liquid leakage based on various causes. However, the matter studied so far is the selection of the resin material, and it is actually possible to use the gasket 20a made of a resin material in which the inner cylindrical portion 27a and the other portions (23, 24, 26a) are actually different. The battery 1a was not manufactured. Therefore, in the following, the inner cylinder portion 27a and the other parts (23, 24, 26a) actually produce the gasket 20a made of the first resin material and the second resin material, respectively, and the gasket 20a itself. Alternatively, it was verified whether or not the alkaline battery 1a incorporating the gasket 20a can withstand practical use.

<Manufacturing method>
First, a manufacturing method of the gasket 20a made of a resin material in which the inner cylindrical portion 27a and other portions (23, 24, 26a) are different will be described. 5A to 5D show an outline of the manufacturing method. In this figure, the shape of the mold 50 and the injection space (51, 53) of the resin material formed in the mold 50 are simplified.

  First, as shown in FIG. 5A, a movable spacer 52 is inserted into an injection space 51 for molding the inner cylinder portion 27a in an injection molding die 50. Next, as shown to (B), the 2nd resin material 60 fuse | melted in the injection | emission space 53 which has the shape of parts (23, 24, 26a) other than the inner cylinder part 27a is inject | emitted. When the second resin material 60 is cooled and solidified, as shown in (C), a molded product (hereinafter referred to as a pre-molded product) 61 that becomes a part (23, 24, 26a) other than the inner cylindrical portion 27a is formed. . In this state, the movable spacer 52 is pulled out. And as shown to (D), the molten 1st resin material 62 used as the inner cylinder part 27a is inject | emitted to the injection space 51, leaving the pre-molded product 61 in the same metal mold | die 50. FIG. At this time, the pre-formed product 61 melts the contact interface with the melted first resin material 62, and the first resin material and the second resin material melt at the contact interface. When the contact interface between the first resin material and the first resin material is cooled and solidified, the gasket 20a in which the inner cylindrical portion 27a is fixed and integrated inside the pre-formed product 61 is completed. In the following description, a portion formed of the first resin material is referred to as a first resin portion, and a portion formed of the second resin material is referred to as a second resin portion.

<Modification example of gasket>
The gasket 20a according to the embodiment of the present invention shown in FIG. 3 is a first resin material and a second resin material in which the inner cylinder portion 27a and other portions (23, 24, 26a) have different physical properties. It was characterized by the structure of being formed. However, not only the gasket 20a shown as one embodiment in FIG. 3, but the inner peripheral side of the boss portion 21 in contact with the negative electrode current collector 6 is the first resin material and the other portions are the second resin material. A structure other than the gasket 20a shown in FIG. 3 is also conceivable. That is, various gaskets in which the position and shape of the bonding interface between the first resin portion and the second resin portion are considered. FIG. 6 illustrates several gaskets (20a to 20d) having a structure in which the first and second resin materials are integrally molded.

  The gasket 20a shown in FIG. 6 (A) has the same structure as that shown in FIG. 3, the inner cylindrical portion 27a is the first resin portion 70a, and the other portions (23, 24, 26a) are the first ones. 2 resin parts 71a. And the outer cylinder part 26a of the boss | hub part 21 covers the periphery of the lower surface of the inner cylinder part 27a, the inner cylinder part 27a does not extend to the lower end 28 of the boss | hub part 21, but only the center vicinity of the lower surface 29 is exposed below. ing. A bonding interface 30a between the first resin portion and the second resin portion serves as a boundary surface between the outer cylinder portion 26a and the inner cylinder portion 27a.

  The gasket 20b shown in FIG. 6 (B) is formed of a resin material in which the inner cylindrical portion 27b is the first resin portion 70b and the other portions (23, 24, 26b) are the same as in (A). Although the second resin portion 71b is formed, the inner cylinder portion 27b extends to the lower end 28 of the boss portion 21, and the entire lower surface 29 is exposed downward. Also in this case, the bonding interface 30b between the first resin portion 70b and the second resin portion 71b serves as a boundary surface between the outer cylinder portion 26b and the inner cylinder portion 27b, but the area of the bonding interface 30b is equal to the outer cylinder portion 26b. Is smaller than the bonding interface 30a in the gasket 20a shown in FIG.

  The gasket 20c shown in FIG. 6C is a first resin portion 70c in which the entire boss portion 21 is formed of a first resin material, and a partition wall portion 23 and an outer peripheral portion 24 are formed of a second resin material. 2 resin portions 71c. The boundary between the boss portion 21 and the partition wall portion 23 is a bonding interface 30c. Although the gasket 20d shown in (D) is entirely formed of the first resin material, the gasket 20d extends inward so that the inner peripheral side of the partition wall portion 23 is embedded in the boss portion 21, The tip is thicker than the thin portion 25. Then, the bonding interface 30 d becomes a tip portion of the partition wall portion 23 embedded in the side surface of the boss portion 21. Accordingly, the first resin portion 70d is a portion excluding the tip portion of the embedded partition wall portion 23 from the boss portion 21. A portion from the tip end portion of the partition wall portion 23 embedded in the boss portion 21 to the outer peripheral portion 24 through the partition wall portion 23 becomes the second resin portion 71d. The gasket 20e shown in (E) has a bonding interface 30e in the partition wall portion 23, and the first resin material portion extends from the boss portion 21 to the bonding interface 30e on the way to the outside from the inner peripheral side of the partition wall portion 23. 70e.

  In addition, about the gaskets 20b-20e of the structure shown to FIG.6 (B)-(E), the shape and moving direction of the movable spacer 52 arrange | positioned in the metal mold | die 50 used for the injection molding previously shown in FIG. Can be manufactured by a well-known two-color molding method, such as using two molds that individually mold the first resin portion and the second resin portion.

<Optimum gasket structure>
As described above, the structure of various gaskets (20a to 20e) according to the position and shape of the bonding interface (30a to 30e) between the first resin portion (70a to 70e) and the second resin portion (71a to 71e). However, it is necessary to verify whether the gaskets (20a to 20e) having these structures can withstand practical use. Therefore, in addition to the five types of gaskets (20a to 20e) shown in FIG. 6, an alkaline battery is manufactured using the conventional gasket 20 shown in FIG. 2, and these three kinds of alkaline batteries are used as samples. (90 ° C./Dry storage test, 60 ° C. 90% RH storage test, 60 ° C. 50% RH storage test). Further, a hollow sample in which the opening of the battery can 2 is simply sealed with the negative electrode terminal plate 7 through a gasket (20, 20a to 20e) is also produced, and a hole is formed in the bottom of the hollow battery can 2. Compressed air was injected from above to conduct an operation test (operating pressure test) of the explosion-proof safety mechanism. That is, it was examined whether or not the explosion-proof safety mechanism operates within the pressure range defined by the alkaline battery standard.

  Furthermore, the moldability at the time of injection molding was also examined. Specifically, for the gaskets (20a to 20d) having the structures shown in FIG. 6 and the conventional gasket 20, the gaskets (20, 20a to 20) Before incorporating 20e) into the battery can 2, each individual was visually inspected to determine whether or not the molding state was uniform among a plurality of individual gaskets (20, 20a to 20e) having the same structure. Further, it was also visually checked whether or not there is a joint mark (weld) at the joint interface (30a to 30e) between different resin materials.

  In addition, about the resin material which forms a gasket (20, 20a-20e), about the conventional gasket 20, the sample which made all nylon 6-6 and the sample which made all nylon 6-12 were produced, For the gaskets (20a to 20e) shown in FIG. 6, the resin material of the first resin portion (70a to 70e) is nylon 6-6 that has the optimum values of the tensile strength and the Rockwell hardness defined earlier. The two resin parts (71a to 71e) were made of nylon 6-12 in which the equilibrium water absorption rate and Rockwell hardness were the optimum values specified previously. Of course, the 1st resin part (70a-70e) and the 2nd resin part (71a-71e) do not need to be nylon 6-6 and nylon 6-12, but each resin part (70a-70e, 71a-71e). Each of these may have the appropriate physical properties described above.

Table 4 shows the correspondence between the gasket structure and various test results.

  In Table 4, the gasket structure is indicated by the reference numerals described in the above figures. That is, the samples 32 and 33 are the conventional gasket 20 shown in FIG. Moreover, the sample 34 is the gasket 20a shown to FIG. 3 and FIG. 6 (A), and the samples 36-38 are the gaskets (20b-20e) shown to FIG. 6 (B)-(E), respectively. . In addition, for moldability, “○” is used to indicate the case where uniform molding between solids is possible, and although molding is possible, the shape and size of the molding state is a predetermined error. A case where it is out of range and non-uniform or a weld occurs is indicated by “Δ”.

  First, among the samples 32 to 38, the sample 32 actually uses the conventional gasket 20 with no distinction between the first resin portion and the second resin portion, and the tensile strength of the gasket 20 is the optimum value. It is made of nylon 6-6 which can be reliably prevented from leaking due to the creep phenomenon. In this sample 32, no leakage occurred in all individuals in the 90 ° C. Dry storage test, but 60 ° C. and 90% R.D. H. In the storage test, leakage (valve operation) caused by activation of the explosion-proof safety mechanism occurred in 30% of individuals. Similarly to the sample 32, the conventional gasket 20 and the sample 33 using nylon 6-12 as the resin material have a temperature of 60 ° C. and 90% R.D. H storage test and 60 ° C. 50% R.D. H. In the storage test, no individual leaked liquid, but in the 90 ° C Dry storage test, liquid leakage (valve operation) due to cracking of the boss portion occurred in 10% of the individuals.

  On the other hand, of the samples 34 to 38 using the gaskets (20a to 30e) shown in FIGS. 6A to 6E, the samples 36 other than the samples 34 and 35 in which the boss portion 21 has a double cylindrical shape. -38, 60C 50% R.V. H. In the test, there was an individual that leaked from the bonding interface (30c to 30e). This is presumably because the bonding strength between the first resin material and the second resin material was low due to the small cross-sectional area of the bonding interface (30c to 30e). In samples 36 and 37, there were individuals in which the explosion-proof safety mechanism was operated at a pressure lower than the standard in the operating pressure test. This is presumably due to the presence of the joining interface (30c, 30d) in the vicinity of the thin-walled portion 25 that is pre-ruptured in the gasket (20c, 20d). In the samples 37 and 38 where the boundary portion between the partition wall portion 23 and the boss portion 21 or in the middle of the partition wall portion 23 has the bonding interface (30d, 30e), welds were generated at the bonding interface (30d, 30e). There are individuals and it is hard to say that they have good moldability.

  And in the samples 34 and 35 using the gaskets (20a and 20b) in which the boss portion 21 has a double cylindrical shape shown in FIGS. 6 (A) and 6 (B), the area of the joining interface (30a and 30b). Was sufficiently wide and no individual had leaked through each storage test. In addition, the operating pressure is normal in all individuals, and although there is a complexity in the process of integrally molding two types of resin, it is possible to mold by general injection molding technology, and generation of welds There was no problem with moldability. As described above, the gasket (20a, 20b) in which the boss portion 21 has a double cylindrical shape including the outer cylindrical portion (26a, 26b) and the inner cylindrical portion (27a, 27b) is an embodiment of the present invention.

<Optimal shape of the boss>
As described above, the gasket (20a, 20b) according to the embodiment of the present invention is characterized in that the boss portion 21 has a double cylindrical shape. Therefore, as shown in FIG. 7, with respect to the gasket 20a shown in FIG. 3 and FIG. 6 (A), the ratio φi / φo between the diameter φo of the outer cylindrical portion of the boss portion 21 and the diameter φi of the inner cylindrical portion. We investigated whether there was any significance. Specifically, the inner diameter φ1 of the boss hole 22 is φ1 = 1.45 mm, and the ratio (cylinder portion diameter ratio) between the diameter φo of the outer cylindrical portion 26a of the boss portion 21 and the diameter φi of the inner cylindrical portion 27a is different. Various gaskets 20a are prepared, and a test needle test is performed in which a test needle having an outer diameter of 1.7 mm is inserted into the boss hole 22 with respect to the inner diameter φ1 = 1.45 mm of the boss hole 22 to determine whether the boss portion 21 is cracked. While confirming, the hollow battery which sealed the battery can 2 was produced using the various gaskets 20a from which this cylinder part diameter ratio (phi) i / (phi) o differs, and said operating pressure test was done. Here, 40 gaskets 20a produced under the same conditions were produced. Further, the moldability was examined when the gasket 20a was produced.

Table 5 shows the tube diameter ratio and the results of moldability, test needle test, and operating pressure test.

  Table 5 shows the results of moldability, a test needle test, and an operating pressure test for each sample, using a gasket 20a manufactured under the same conditions and a hollow battery using the gasket 20a as samples. The formability was indicated by “」 ”,“ 」”, and “x” in order from the good state according to the molding state and the difficulty of management during molding. And in the samples 39 and 40 in which the cylinder part diameter ratio (φi / φo × 100) expressed as a percentage is 30% or less, the outer cylinder part 26a is too thin, so that the molding itself cannot be performed, and “x” determination is made. It was. Therefore, the test needle test and the working pressure test for these samples 39 and 40 were not performed.

  In addition, in the samples 41 and 45 having the cylinder part diameter ratio of 40% or 95%, the outer cylinder part 26a is thinner or thicker than other samples, so that the resin temperature during molding, the cooling time after molding, etc. If the management was not rigorous, there was a tendency for the variation among individuals to increase, and a “◯” determination was made. For samples 42 to 44 having a boss inner circumference ratio of 50% ≦ φi / φo ≦ 90%, there was no problem in moldability, and “◎” was determined.

  Regarding the test needle test, among samples 41 to 45, sample 41 with a thin boss outer peripheral portion had an individual in which boss cracking occurred. Further, in the sample 45 having a 90% thick outer peripheral portion of the boss, there was an individual in which the explosion-proof safety mechanism was operated at a pressure lower than the pressure range defined by the standard.

1, 1a alkaline battery, 2 battery can (battery can), 3 positive electrode mixture, 4 separator,
5 negative gel, 6 negative current collector, 7 negative terminal plate, 8 positive terminal,
20, 20a-20e gasket, 21 boss part, 22 boss hole,
23 partition part, 24 outer peripheral part, 25 thin part, 26a, 26b outer cylinder part,
27a, 27b inner cylinder part, 30a-30e joint interface, 50 mold,
51, 53 Injection space, 52 Movable spacer, 60 Second resin material,
62 1st resin material, 70a-70e 1st resin part, 71a-71e 2nd resin part φo Outer diameter of boss part (outer cylinder part), φi Outer diameter of inner cylinder part, φ1 Inner diameter of boss hole

Claims (4)

In a bottomed cylindrical battery can with the bottom at the bottom, a circular positive electrode mixture, a bottomed cylindrical separator arranged inside the positive electrode mixture, and a negative electrode gel arranged inside the separator And the gasket in the alkaline battery in which a negative electrode terminal plate is fitted to the opening of the battery can via a gasket for sealing,
The gasket is made of an integrally molded resin material, and has a disk-shaped partition wall, an outer peripheral portion standing upward from the periphery of the partition wall, and a hollow cylinder in the vertical direction at the center of the disk-shaped partition wall A boss part protruding in a shape,
The boss part is a double cylinder composed of an outer cylinder part and an inner cylinder part arranged coaxially,
The inner cylinder portion is formed of a first resin material;
The outer cylinder part of the boss part, the partition part continuous to the outer cylinder part, and the outer peripheral part are formed of a second resin material having different physical properties from the first resin material.
A gasket for an alkaline battery. In claim 1,
The first resin material has a tensile strength of 65 MPa or more and a Rockwell hardness of R100 or more and R120 or less,
The second resin material has an equilibrium water absorption of 5.00% or less and a Rockwell hardness of R100 or more and R120 or less.
A gasket for an alkaline battery.   In Claim 1 or 2, the ratio φi / φo × 100 (%) between the outer diameter φo of the outer cylinder portion of the boss portion and the outer diameter φi of the inner cylinder portion is 50% or more and 90% or less. A gasket for an alkaline battery.   An annular positive electrode mixture, a bottomed cylindrical separator arranged inside the positive electrode mixture, and a negative electrode gel arranged inside the separator are housed in a bottomed cylindrical battery can. An alkaline battery comprising a negative electrode terminal plate fitted into the opening of the battery can via the alkaline battery gasket according to any one of claims 1 to 3.

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