JP4264318B2 - Alkaline battery - Google Patents

Description

  The present invention relates to an alkaline dry battery hermetically sealed with a metal negative electrode terminal plate and a resin sealing gasket. For example, a cylindrical alkaline dry battery such as LR20 (single 1), LR14 (single 2), and LR6 (single AA). It is effective to use.

  FIG. 5 shows a main part of a conventional alkaline battery. In the same figure, (a) is an enlarged sectional view of the sealing portion, and (b) is an overall perspective view of the appearance. The sectional view schematically shows the bent state of the opening of the battery can, but the actual section is more curved than the illustrated state.

  A battery 10 'shown in the figure is a cylindrical alkaline dry battery such as LR20 or LR14, and the opening of a bottomed cylindrical metal battery can 11 containing a power generation element is a dish-shaped metal negative terminal plate. 21 and an electrically insulating resin sealing gasket 31 are hermetically sealed.

  The power generation element includes a positive electrode mixture 12 formed into a tubular shape, a separator 13 impregnated with an alkaline electrolyte, and a negative electrode mixture 14 using gelled zinc. A rod-shaped metal negative electrode current collector 25 penetrates the negative electrode mixture 14.

  The battery can 11 also serves as a positive electrode current collector and a positive electrode terminal, and a protruding positive electrode terminal portion 111 is formed on the bottom thereof by press working. The barrel and upper and lower peripheral edges of the cylindrical battery can 11 are covered in a cylindrical shape with a heat-shrinkable exterior material 15. The exterior material 15 functions as a battery label and a cosmetic exterior. Moreover, the whole except the battery terminal part of both end surfaces is electrically insulated (see Patent Document 1).

  The sealing gasket 31 is a disk-shaped (or hat-shaped) molded product, and includes an outer peripheral portion 32, a central boss portion 33, an intermediate partition wall portion 34, a thin portion 35, and the like. The outer peripheral portion 32 is hermetically sealed in the battery can 11 by being interposed between the battery can 11 and the negative electrode terminal plate 21 in a pressurized state. The negative electrode current collector 25 is inserted through the central boss portion 33. The thin portion 35 forms a safety valve, and when the internal pressure of the battery abnormally increases, the thin portion 35 breaks prior to release the internal pressure and prevent the battery from bursting.

The negative electrode terminal plate 21 has the negative electrode current collector 25 connected and fixed to the center of the battery side surface (inner side surface) by spot welding or the like. In addition, a small vent hole 23 is formed as a gas vent when the safety valve (thin wall portion 35) is operated. The vent hole 23 is provided at a position communicating with the space between the negative terminal plate 21 and the gasket 31. The vent hole 23 is exposed to the outside. Therefore, the front end 15 e of the exterior material 15 is located outside the vent hole 23.
JP-A-9-259843

  In this type of alkaline dry battery, improvement in leakage resistance performance is a major issue. Various solutions have been proposed for a long time, and some of them have been used in practice. But still not perfect.

  As a result of intensive studies on the leakage phenomenon of alkaline batteries, particularly the leakage phenomenon caused by long-term storage, the present inventors have found that there is a specific cause of leakage in the structure of the alkaline batteries described above.

  That is, the conventional alkaline battery shown in FIG. 5 has a safety valve formed by a thin portion 35 in a part of the gasket 31 and a gas vent in the negative terminal plate 21 in order to prevent rupture due to an abnormal increase in battery internal pressure. Ventilation holes 23 are provided.

  In this case, the gasket 31 is made of an alkali-resistant polyamide resin (nylon) or the like. The inner space (battery side) of the negative electrode terminal plate 21 communicates with the outside air through the vent hole 23, but is hermetically isolated from the inside of the battery by the gasket 31. Therefore, from the viewpoint of mechanical structure, the alkaline electrolyte is confined inside the gasket 31, that is, inside the battery.

  However, since this type of alkaline dry battery uses a high-concentration alkaline solution as the alkaline electrolyte, external moisture permeates through the gasket 31 and is absorbed by the alkaline electrolyte when stored for a long time in a high humidity environment. Phenomenon occurs.

  Although the gasket 31 is configured to mechanically prevent the direct leakage of the alkaline electrolyte, it cannot completely block the permeation of moisture during long-term storage. Moisture that has penetrated the gasket 31 and entered the inside of the battery occupies the air chamber inside the battery and contributes to an increase in internal pressure, which causes liquid leakage at an early stage.

  Here, according to the present inventors, it has been found that the vent hole 23 provided in the negative electrode terminal plate 21 is the main moisture infiltration path. Therefore, prior to the present invention, the present inventors examined a structural means for closing the vent hole 23.

  Alkaline dry batteries having a structure that closes the vent holes 23 also existed in the past. For example, in the alkaline battery described in Patent Document 2, an insulating ring is placed on the negative electrode terminal plate, and this insulating ring is placed at a position to close the ventilation hole of the negative electrode terminal plate.

  However, the insulating ring is originally a kind of insulating spacer that prevents the negative terminals from being erroneously connected to each other, and has a slight effect on suppressing moisture intrusion from the vent hole. However, it was found that the cause of the early leakage was not solved.

The present invention has been made in view of the above problems, and in an alkaline dry battery having a safety valve function necessary for preventing the battery from rupturing, the rate of leakage due to long-term storage is a relatively simple and easy-to-implement means. There is a significant reduction.
JP-A-10-188948

The first means of the present invention is a bottomed cylindrical metal battery can also serving as a positive electrode terminal, a power generation element containing an alkaline electrolyte accommodated in the battery can, and an upper part as a bottom. A metal negative electrode terminal plate that forms an end surface of the cylindrical battery by interposing it in the upper opening of the battery can in the shape of a dish, and is interposed between the opening of the battery can and the negative electrode terminal plate to seal the battery can. An electrically insulating resin sealing gasket that is hermetically sealed, a safety valve that is formed on a part of the gasket and that operates when the battery internal pressure rises abnormally, and a peripheral surface that serves as a side surface of the dish in the dished negative terminal plate Formed in the shape of a small vent hole when the safety valve is actuated and formed into a cylindrical shape that opens up and down, and electrically insulates and coats the body and upper and lower peripheral edges of the battery can An alkaline battery provided with a shrinkable exterior material,
The cylindrical exterior material is a water-impermeable material, and an upper end portion covers an annular surface portion including the peripheral surface and a bottom periphery of the dish-shaped negative electrode terminal plate, and the one end portion serves as a negative electrode terminal plate. Glued,
That the peripheral surface including the vent hole is covered with the exterior material, so that the portion including the inner surface of the dished negative terminal plate including the vent hole and the gasket is hermetically cut off. Features.

  In the above means, it is desirable that the exterior material is constituted by using a PET (polyethylene terephthalate) resin as a base material. Further, in the above means, it is desirable that the exterior material has a metal layer made of a thin film or a foil, and at least a portion applied to the negative electrode terminal plate is electrically insulated.

  In an alkaline dry battery having a safety valve function necessary for preventing the battery from bursting, the leakage generation rate due to long-term storage is to be significantly reduced by a relatively simple and easy-to-implement means.

  FIG. 1 shows a main part of an alkaline battery according to an embodiment of the present invention. In the same figure, (a) is an enlarged sectional view of the sealing portion, and (b) is an overall perspective view of the appearance. The sectional view schematically shows the bent state of the opening of the battery can, but the actual section is more curved than the illustrated state.

  The battery 10 shown in the figure is a cylindrical alkaline battery such as LR20 or LR14, and the opening of a bottomed cylindrical metal battery can 11 containing a power generation element is a dish-shaped metal negative electrode terminal plate 21. Are hermetically sealed by an electrically insulating resin sealing gasket 31.

  The power generation element is configured using a positive electrode mixture 12, a separator 13, and a negative electrode mixture 14. The positive electrode mixture 12 is molded and solidified into a tubular shape, and is inserted into the battery can 11. A cylindrical separator 13 is disposed inside the positive electrode mixture 12. The separator 13 is impregnated with an alkaline electrolyte made of a high concentration alkaline solution (strong alkali). The separator 13 is filled with a negative electrode mixture 14 using gelled zinc. A rod-shaped metal negative electrode current collector 25 penetrates the negative electrode mixture 14.

  The battery can 11 also serves as a positive electrode current collector and a positive electrode terminal, and a protruding positive electrode terminal portion 111 is formed on the bottom thereof by press working. The body and upper and lower peripheral edges of the battery can 11 are covered with a heat-shrinkable exterior material 15 in a cylindrical shape. The exterior material 15 functions as a battery label and a cosmetic exterior. Moreover, the whole except the part used as the battery terminal of both end surfaces is electrically insulated.

  The sealing gasket 31 is a coaxial disk-shaped resin molded product, and is formed with an outer peripheral portion 32, a central boss portion 33, an intermediate partition wall portion 34, a thin portion 35, and the like. The outer peripheral portion 32 is hermetically sealed in the battery can 11 by being interposed between the battery can 11 and the negative electrode terminal plate 21 in a pressurized state. The negative electrode current collector 25 is inserted through the central boss portion 33. The thin portion 35 forms a safety valve, and when the internal pressure of the battery abnormally increases, the thin portion 35 breaks prior to release the internal pressure and prevent the battery from bursting.

  The negative electrode terminal plate 21 is made of a plate-shaped (or hat-shaped) metal, and the negative electrode current collector 25 is connected and fixed to the center of the battery side surface (inner side surface) by spot welding or the like. In addition, a small vent hole 23 is formed as a gas vent when the safety valve (thin wall portion 35) is operated. The vent hole 23 is provided at a position communicating with the space between the negative terminal plate 21 and the gasket 31.

  Here, in this embodiment, in the configuration described above, the exterior material 15 is configured using a water-impermeable material such as a PET (polyethylene terephthalate) resin as a base material. At the same time, one end portion of the exterior material 15 is covered with an annular surface portion including the vent hole 23 of the negative electrode terminal plate 21. For this reason, the front end 15 e of the exterior material 1 reaches the inside of the ventilation hole 23. Further, at least one end thereof is bonded to the negative terminal plate 21 with the adhesive 16. Thereby, the portion including the gasket 31 and the vent hole 23 is hermetically cut off from the outside (outside air).

  As the material (base material) of the exterior material 15, PVC (polyvinyl chloride) resin can be used in addition to the above PET. However, according to what the present inventors have learned, it has been found that PET is particularly suitable for airtightly blocking the vent hole 23. PET has a particularly good function of blocking gas permeation, so-called gas barrier properties, and covers the air holes 23 and the like with an exterior material 15 using this PET resin, and one end of the negative electrode terminal plate with an adhesive 16. By adhering to 21, moisture intrusion into the battery can be greatly reduced, and early leakage can be effectively prevented.

Examples of the present invention and comparative examples thereof are shown below.
<Comparative example>
First, as Comparative Examples 1 and 2, the following two types of alkaline batteries (specifications A and B) were produced.
==== Comparative Example 1 (Specification A) =====
An alkaline battery having the structure shown in FIG. 5 was produced. A PVC resin was used as the material (base material) of the exterior material 15. As shown in FIG. 5, the front end 15 e of the exterior material 15 is located outside the ventilation hole 23.

==== Comparative Example 2 (Specification B) =====
In the configuration of Comparative Example 1, an alkaline dry battery in which an insulating ring (washer) was placed on a vent hole for venting was prepared in the same manner as that described in Patent Document 2. The insulating ring was fixed by being sandwiched between the ends of the exterior material. PVC resin was used for the material (base material) of the exterior material. The front end of the exterior material is located outside the ventilation hole, but the ventilation hole is closed by the insulating ring. The other basic structure is the same as that of Comparative Example 1 (Specification A).

<Example>
Next, as Examples 1 and 2 of the present invention, the following two types of alkaline dry batteries (specifications C and D) were produced.

Example 1 (Specification C) =====
An alkaline dry battery having the structure shown in FIG. 1 was produced. A PVC resin was used as the material (base material) of the exterior material 15. As described above, one end portion of the exterior material 15 is covered with the vent hole 23 and bonded to the negative terminal plate 31.

Example 2 (Specification D) =====
Similar to Example 1, an alkaline dry battery having the structure shown in FIG. In Example 2, PET resin was used as the material (base material) of the exterior material 15, but the rest was the same as Example 1.

<Test 1>
About each alkaline dry battery of Comparative Examples 1 and 2 (specifications A and B) and Examples 1 and 2 (specifications C and D), 60 ° C. and 90% R.D. H. A test was conducted to examine the occurrence of leakage when stored in the environment. In this test, 20 samples were used for each specification (A to D), and the number of storage days until the first one leaked was examined.

The results are shown in Table 1.

  As is clear from Table 1, when Examples 1 and 2 (specifications C and D) and Comparative Examples 1 and 2 (specifications A and B) are compared, the period until the first leakage occurs is , 2 is significantly longer. This indicates that the configurations of Examples 1 and 2 have the effect of greatly reducing the rate of leakage caused by long-term storage. Further, when Example 1 (Specification C) and Example 2 (Specification D) are compared, Example 2 (Specification D) is much longer in the period until the first occurrence of liquid leakage. This indicates that the configuration of Example 2 is more effective in reducing the rate of leakage caused by long-term storage.

  Here, the effects of Examples 1 and 2 (specifications C and D) are achieved by the configuration at one end of the exterior material 15. Further, the effect of the second embodiment (specification D) is achieved by the material configuration of the exterior material 15. With such a relatively simple and easy-to-implement configuration, the rate of liquid leakage due to long-term storage can be greatly reduced.

  Note that one end portion of the exterior member 15 covering the small ventilation hole 23 is peeled off or broken at a relatively low pressure against a large battery internal pressure that activates the safety valve by the thin portion 35. Therefore, the function of the safety valve aiming at preventing dangerous explosion is maintained. One end portion of the exterior member 15 bonded to the negative electrode terminal plate 21 also functions as a safety valve of a pre-breaking type (or a pre-destructing type) like the thin portion 35.

  FIG. 2 is a graph showing the test results obtained by examining the state of moisture ingress in the long-term storage test. In this test, the alkaline dry batteries of Comparative Examples 1 and 2 (specifications A and B) and Examples 1 and 2 (specifications C and D) were each subjected to 60 ° C. and 90% R.D. H. The weight increase (g) when stored in the environment of In this case, the weight increase amount substantially corresponds to the water intrusion amount, and the smaller the weight increase amount, the smaller the water intrusion amount.

<Test 2>
According to the graph of the figure, when Examples 1 and 2 (specifications C and D) and Comparative Examples 1 and 2 (specifications A and B) are compared, the weight increase rate of Examples 1 and 2 is significantly low. It has become. This means that the water ingress during storage is greatly reduced. Moreover, when compared between Example 1 (specification C) and Example 2 (specification D), the weight increase rate of Example 2 is low specifically. That is, by using a PET resin for the base material of the exterior material 15, the effect of suppressing moisture intrusion can be remarkably enhanced and the liquid leakage occurrence rate can be greatly reduced.

  The moisture penetration preventing effect of Example 2 is due to the high gas barrier property of PET resin. This gas barrier property can be further enhanced by laminating a metal layer 152 such as aluminum on the exterior material 15 as shown in FIG.

  FIG. 3 shows a cross-section of an exterior material portion constituting the main part of another embodiment of the present invention. (A) and (b) of the figure schematically show a cross-sectional structure at one end of the exterior material 15, and the exterior material 15 is made of resin and is made of a metal such as aluminum on the film base 151. A layer 152 is stacked. The metal layer 152 formed by bonding (laminating) a metal foil, particularly an aluminum foil, is optimal in terms of gas barrier properties and cost. However, other metal thin films formed by plating or the like can also be used as the metal layer 152.

  By using the exterior material 15 as described above, it is possible to reliably increase the effect of suppressing water intrusion that causes liquid leakage, and to significantly reduce the liquid leakage occurrence rate. In this case, since the outer covering material 15 covers the positive electrode terminal portion and the negative electrode terminal portion of the battery, there is a risk that the two electrode terminal portions are bridged and short-circuited by the metal layer 152. In order to surely avoid this short circuit, as shown in (a) or (b) of the figure, it is only necessary to insulate at least a portion of the exterior material 15 that is applied to the negative electrode terminal plate 21.

  In the embodiment shown in (a) of the figure, the short circuit is avoided by covering the metal layer 152 of the exterior material 15 that covers the negative electrode terminal plate with the insulating layer 153. Further, in the embodiment shown in FIG. 5B, the short circuit is avoided by laminating the insulating layer 153 on the entire surface of the metal layer 152. The insulating layer 153 can be formed by bonding (laminating) or applying an insulating material with resin or the like.

  As mentioned above, although this invention was demonstrated based on the typical Example, this invention can have various aspects other than having mentioned above. For example, in the embodiment shown in FIG. 1, the exterior material 15 is bonded to the negative electrode terminal plate 21 in a completely adhered state without a gap, but as shown in FIG. It may be bonded in a state where a space (air chamber) is formed.

  In an alkaline dry battery having a safety valve function for preventing battery rupture, the rate of leakage due to long-term storage can be greatly reduced by a relatively simple and easy means.

It is principal part sectional drawing and external appearance perspective view of the alkaline dry battery by this invention. It is a graph which shows the weight increase rate by the water | moisture-content penetration | permeation when an alkaline dry battery is preserve | saved for a long term. It is sectional drawing which shows embodiment of the cross-sectional structure in the one end part of an exterior material. It is principal part sectional drawing which shows another embodiment regarding the adhesion state between an exterior material and a negative electrode terminal board. It is principal part sectional drawing and the external appearance perspective view of the conventional rain temporary dry battery.

Explanation of symbols

10 Alkaline battery (the present invention)
10 'alkaline battery (conventional)
DESCRIPTION OF SYMBOLS 11 Metal battery can 111 Protruding positive electrode terminal part 12 Positive electrode mixture 13 Separator 14 Negative electrode mixture 15 Exterior material 15e End 15e of exterior material
151 Base material 152 Metal layer 153 Insulating layer 16 Adhesive 21 Negative electrode terminal plate 23 Venting small hole 25 Negative electrode current collector 31 Resin sealing gasket 32 Outer peripheral part 33 Central boss part 34 Intermediate partition part 35 Thin wall part (safety valve)

Claims (3)

A metal battery can also serving as a positive electrode terminal in a bottomed cylindrical shape with the bottom at the bottom, a power generation element containing an alkaline electrolyte accommodated in the battery can, and a dish-like shape with the bottom at the top above the battery can A metal negative electrode terminal plate which is interposed between the opening and forms one end surface of the cylindrical battery, and an electrically insulating resin which is hermetically sealed between the battery can opening and the negative electrode terminal plate. A sealing gasket, a safety valve that is formed on a part of the gasket and that operates when the internal pressure of the battery is abnormally increased, and the safety valve that is formed on the peripheral surface serving as the side surface of the dish in the dished negative terminal plate And a heat-shrinkable exterior material that is molded into a cylindrical shape that is open at the top and bottom, and that electrically insulates and coats the body and upper and lower peripheral edges of the battery can. An alkaline battery,
The cylindrical exterior material is a water-impermeable material, and an upper end portion covers an annular surface portion including the peripheral surface and a bottom periphery of the dish-shaped negative electrode terminal plate, and the one end portion serves as a negative electrode terminal plate. Glued,
That the peripheral surface including the vent hole is covered with the exterior material, so that the portion including the inner surface of the dished negative terminal plate including the vent hole and the gasket is hermetically cut off. Characteristic alkaline battery.   2. The alkaline dry battery according to claim 1, wherein the exterior material is configured using a PET (polyethylene terephthalate) resin as a base material. 3. The alkaline dry battery according to claim 1, wherein the exterior material has a metal layer made of a thin film or a foil, and at least a portion applied to the negative electrode terminal plate is electrically insulated.