JP2007175871A - Composite rubber sheet and safety valve for hermetically closed type secondary cell using it as valve body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite rubber sheet enhanced in characteristics such as gas impermeability or the like without damaging the elasticity or the like of a rubber material, and a safety valve for a hermetically closed type secondary cell enhanced in gas impermeability without damaging the elasticity of the rubber material. <P>SOLUTION: The composite rubber sheet 13 is obtained by bonding a thin metal film 22 to the surface of a base material 21 comprising the rubber material. The thin metal film has at least one of characteristics such as gas impermeability, a function for shielding an electromagnetic wave, chemical resistance and decorative properties. A protective layer 23 for protecting the thin metal film is further provided on the surface of the thin metal film. The thin metal film and the protective layer are constituted of a laminated film 31 formed by preliminarily laminating a metal foil layer 32 and a resin film layer 33. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a composite rubber sheet and a safety valve for a sealed secondary battery using the composite rubber sheet as a valve body.

  The rubber material is used to temporarily seal an opening of a structure or the like by inflating with a gas, a gas bag for filling a gas, and a gas bag for filling gas by using its elasticity. Used in gas bags for sealing.

  However, rubber materials are generally gas permeable. For this reason, a certain amount of gas leakage occurs with the passage of time, and the original functions of the safety valve and various gas bags may be deteriorated. In addition to the gas permeability described above, rubber materials are inferior to metal materials in terms of their ability to shield electromagnetic waves, oil resistance, and chemical resistance.

  An object of the present invention is to provide a composite rubber sheet having improved properties such as gas impermeability without hindering elasticity of the rubber material, and further, gas impermeability without hindering elasticity of the rubber material. An object of the present invention is to provide a safety valve for a sealed secondary battery with improved performance.

  The invention described in claim 1 for achieving the above object is a composite rubber sheet obtained by bonding a metal thin film to the surface of a base material made of a rubber material.

In order to achieve the above object, the invention according to claim 5 is provided with a sealing plate that is hermetically attached to the opening of the outer can and has a vent hole, and is attached to the sealing plate and has a vent hole. A safety valve for a sealed secondary battery comprising: a terminal cap; and a valve body disposed in an elastically compressed state so as to cover the gas vent hole between the sealing plate and the terminal cap. ,
The valve body is made of a composite rubber sheet formed by joining a metal thin film having gas impermeability to the surface of a base material made of a rubber material, and the metal thin film is arranged so as to cover the gas vent hole. Is a safety valve for a sealed secondary battery.

  According to the present invention, it is possible to provide a composite rubber sheet having improved properties such as gas impermeability without hindering elasticity of the rubber material, and further, gas impermeability without hindering elasticity of the rubber material. A safety valve for a sealed secondary battery with improved performance can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a composite rubber sheet 11 according to an embodiment of the present invention.

  Referring to FIG. 1, a composite rubber sheet 11 is configured by joining a metal thin film 22 to the surface of a base material 21 made of a rubber material.

  The rubber material is not particularly limited, and examples thereof include ethylene propylene diene terpolymer (EPDM), ethylene propylene rubber (EPM), and natural rubber.

  The metal thin film 22 has at least one characteristic of gas impermeability, a function of shielding electromagnetic waves, oil resistance, chemical resistance, and decorativeness. An appropriate material can be used for the metal thin film 22 from the viewpoint of obtaining desired characteristics. For example, aluminum, copper, nickel, etc. are mentioned.

  The metal thin film 22 can be provided inside the base material 21 except for the case of obtaining a decorative property. However, the metal thin film 22 can be easily manufactured and processed by being provided on the surface of the base material 21.

  The metal thin film 22 is preferably thin enough not to impair the elasticity of the rubber material forming the base material 21 and has a thickness sufficient to prevent pinholes and scratches or cracks during processing. Specifically, the thickness of the metal thin film 22 is preferably 1 μm to 20 μm. If the thickness is less than 1 μm, there is a risk of causing pinholes or scratches or cracks during processing, and if it is 20 μm or more, the flexibility of the rubber material forming the base material 21 may be impaired.

  For bonding the base material 21 and the metal thin film 22, a general rubber adhesive such as a rubber adhesive “Chemlock” (trade name, manufactured by Road Far East Incorporated) can be used. By applying an adhesive to at least one of the bonding surface of the base material 21 and the bonding surface of the metal thin film 22 and hot pressing at a rubber vulcanization temperature (for example, 150 ° C. to 200 ° C.), The metal thin film 22 is joined.

  The composite rubber sheet 11 obtained as described above is formed on the surface of the base material 21 while maintaining the elasticity, compression set resistance, heat aging resistance, etc. inherent to the rubber material forming the base material 21. The bonded metal thin film 22 provides a rubber sheet having at least one of the following characteristics: gas impermeability, function of shielding electromagnetic waves, oil resistance, chemical resistance, and decorativeness.

  In the illustrated example, the metal thin film 22 is bonded to only one of the surfaces in the thickness direction of the substrate 21, but the metal thin film 22 may be bonded to both surfaces of the substrate 21. This is because warpage of the composite rubber sheet 11 that may occur due to hot pressing can be prevented.

  The present invention does not exclude a method of forming a metal film on the surface of the base material 21 by metal vapor deposition or metal sputtering when the metal thin film 22 is bonded to the surface of the base material 21 made of a rubber material. However, since the metal film is easily peeled off or cracked, it can be said that it is preferable to bond the base material 21 and the metal thin film 22 through an adhesive from the viewpoint of long-term adhesion and flexibility. . Furthermore, in order to perform metal vapor deposition etc., expensive equipment is required, the type of rubber to be applied is limited, and processing costs may increase. Also from the viewpoint of eliminating these restrictions, it is preferable to join the base material 21 and the metal thin film 22 through an adhesive.

  FIG. 2 is a cross-sectional view showing a composite rubber sheet 12 according to another embodiment of the present invention.

  With reference to FIG. 2, the composite rubber sheet 12 preferably further includes a protective layer 23 for protecting the metal thin film 22 on the surface of the metal thin film 22. This is because the protective layer 23 prevents the metal thin film 22 from being scratched, and the characteristics enhanced by the metal thin film 22 such as gas impermeability can be maintained over a long period of time.

  The protective layer 23 can be formed from a plastic film laminated on the surface of the metal thin film 22. The plastic used for the protective layer 23 is not particularly limited, and examples thereof include polyethylene (PE), polypropylene (PP), nylon, polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). The plastic film that forms the protective layer 23 may be provided on the surface of the metal thin film 22 after the metal thin film 22 is bonded to the base material 21 by hot pressing, or the metal film simultaneously with the hot pressing for bonding the metal thin film 22 to the base material 21. It may be provided on the surface of the thin film 22. In the latter case, the plastic used for the protective layer 23 is preferably a plastic whose melting point and softening point are higher than the vulcanization temperature of rubber. For example, nylon, PET, PBT, etc. can be suitably used. Although the thickness of the protective layer 23 can employ | adopt an appropriate dimension, it is about 15 micrometers, for example.

  FIG. 3 is a cross-sectional view showing a composite rubber sheet 13 according to still another embodiment of the present invention.

  With reference to FIG. 3, the metal thin film 22 and the protective layer 23 of the composite rubber sheet 13 may be composed of a laminate film 31 in which a metal foil layer 32 and a resin film layer 33 are bonded in advance.

  The metal foil layer 32 is made of, for example, aluminum foil, and the resin film layer 33 is made of a plastic film such as polyester or nylon. The thickness of the aluminum foil is preferably 1 μm to 20 μm. As described above, if it is less than 1 μm, there is a possibility of causing a pinhole or a flaw or crack during processing, and if it is 20 μm or more, the flexibility of the rubber material forming the substrate 21 may be impaired. Although the thickness of the resin film layer 33 can adopt an appropriate dimension, it is, for example, about 15 μm.

  The base material 21 and the laminate film 31 are joined by applying a general rubber adhesive to the laminate film 31 and hot pressing at a rubber vulcanization temperature (for example, 150 ° C. to 200 ° C.).

  By using the laminate film 31 in which the metal foil layer 32 and the resin film layer 33 are bonded in advance, the metal thin film 22 and the protective layer 23 can be handled easily, and the composite rubber sheet 13 can be easily manufactured. Moreover, an expensive installation is not required, the kind of rubber to apply is not restrict | limited, and the raise of processing cost can be suppressed.

  In addition, the laminate film 31 has three layers in which the metal foil layer 32 is sandwiched by the resin film layer 33 from both sides in addition to the illustrated two-layer laminate film in which the resin film layer 33 is bonded to one side of the metal foil layer 32. A type of laminate film can also be used.

  Next, application examples of the composite rubber sheet according to the present invention will be described.

  4A and 4B are sectional views showing a safety valve 40 for a sealed secondary battery using the composite rubber sheet 14 according to the present invention for the valve body 80, and FIG. 5 shows the safety valve 40 shown in FIG. It is sectional drawing which shows the state which assembled | attached to the exterior can 50 of the sealed secondary battery.

  As batteries that can be used repeatedly, sealed secondary batteries such as lithium-hydrogen secondary batteries are widely used. This sealed secondary battery has a chemical reaction with the electrolyte inside the outer can when it is exposed to high temperature due to abnormal current charging or reverse charging due to misuse, or disposal of the battery after use in fire. May abnormally generate gas (for example, hydrogen gas). With abnormal gas generation, the pressure inside the outer can rises. In order to prevent damage to the outer can due to this pressure increase, the sealed secondary battery is provided with a resettable safety valve that releases the gas in the outer can to the outside in response to the pressure increase inside the outer can. ing.

  As shown in FIGS. 4 and 5, the safety valve 40 for the sealed secondary battery is hermetically attached to the opening 51 of the outer can 50 and has a sealing plate 60 in which a gas vent hole 61 is opened, and a sealing plate 60. And a valve cap 80 disposed in an elastically compressed state so as to cover the gas vent hole 61 between the sealing plate 60 and the terminal cap 70. ,have. The outer peripheral edge of the sealing plate 60 is bent inward and is crimped to the terminal cap 70. The safety valve 40 is attached to the opening 51 of the outer can 50 via an insulating gasket 52 (see FIG. 5).

  The composite rubber sheet according to the present invention is used for the valve body 80. That is, the valve body 80 is composed of the composite rubber sheet 14 formed by joining the metal thin film 22 having gas impermeability to the surface of the base material 21 made of a rubber material so that the metal thin film 22 covers the gas vent hole 61. Is arranged. The valve body 80 has a rectangular parallelepiped with a dimension of about 2 mm to 6 mm, for example.

  The rubber material of the base material 21 is not particularly limited as long as it has elasticity. For example, a rubber material mainly composed of EPDM can be exemplified. Although the thickness dimension of the composite rubber sheet 14 is not specifically limited, When using for the valve body 80 of said safety valve 40, a thickness dimension is about 2 mm-6 mm, for example.

  The safety valve 40 further includes a protective layer 23 for protecting the metal thin film 22 on the surface of the metal thin film 22.

  The metal thin film 22 and the protective layer 23 are composed of a laminate film 31 in which a metal foil layer 32 and a resin film layer 33 are bonded in advance. The metal foil layer 32 is made of, for example, an aluminum foil that has high gas impermeability to hydrogen gas. The resin film layer 33 is made of a plastic film such as nylon that is not hydrolyzed by the electrolytic solution. The thickness of the aluminum foil is preferably 1 μm to 20 μm. If the thickness is less than 1 μm, there is a risk of causing pinholes or scratches or cracks during processing, and if it is 20 μm or more, the flexibility of the rubber material forming the base material 21 may be impaired. Although the thickness of the resin film layer 33 can adopt an appropriate dimension, it is, for example, about 15 μm.

  The composite rubber sheet 14 is cut into a plurality of elastic pieces that form a rectangular parallelepiped, and these individual elastic pieces are used as the valve body 80. The composite rubber sheet 14 is preferably bonded to the laminate film 31 on both surfaces of the base material 21 in the thickness direction. This is because warpage of the composite rubber sheet 14 that may occur due to hot pressing can be prevented. Further, the metal thin film 22 is bonded to each of two opposing surfaces of the elastic piece after the cutting process. For this reason, when the valve body 80 is arranged so that the metal thin film 22 covers the gas vent hole 61, one of the two surfaces may face the gas vent hole 61, and the metal thin film 22 is provided only on one surface. Compared to the case, the operation of adjusting the posture of the valve body 80 is simplified.

  When the valve body 80 is obtained, a process of applying and drying an adhesive on the laminate film 31 and a process of cutting the laminate film 31 are further required as compared with the case where the valve body is formed of a rubber material alone. The process and equipment for forming the valve body with the rubber material alone can be applied to the process of creating the sheet 14 (mixing, sheeting, cutting, vulcanization) and the process of cutting the composite rubber sheet 14 as they are. .

As shown in FIG. 4B, the safety valve 40 configured as described above is configured such that when the pressure inside the outer can 50 rises to a value higher than a certain value, the gas pressure connects the valve body 80 through the gas vent hole 61. It pushes up to the cap 70 side and compresses to open the gas vent hole 61. When the gas vent hole 61 is opened, the gas inside the outer can 50 flows out into the space surrounded by the sealing plate 60 and the terminal cap 70 as indicated by a one-dot chain line, and further, the vent hole 71 of the terminal cap 70. It is discharged to the outside through. As a result, the outer can 50 is prevented from being damaged due to the pressure increase. When the pressure inside the outer can 50 becomes a certain value or less as the gas is released, the valve body 80 expands again by its own elastic force and automatically returns to the state in which the gas vent hole 61 is closed. The safety valve 40 having the above configuration is designed to operate in a pressure range of 2.94 to 3.92 MPa (30 to 40 kgf / cm ² ), for example.

  Since the metal thin film 22 covers the gas vent hole 61, the valve body 80 has higher gas impermeability than a mode in which the gas vent hole 61 is covered with a valve body made of only a rubber material. Therefore, it is possible to provide a safety valve 40 for a sealed secondary battery with improved gas impermeability without hindering the elasticity of the rubber material. For example, in a lithium-hydrogen secondary battery, the permeation of hydrogen gas in the state where the safety valve 40 is closed is reliably prevented, and a longer life and higher performance than the case where a valve body is formed by a rubber material alone. The lithium-hydrogen secondary battery can be provided.

  As the laminate film 31, in addition to the illustrated two-layer type laminate film, a three-layer type laminate film in which the metal foil layer 32 is sandwiched by the resin film layers 33 from both sides thereof can also be used.

  6A is a cross-sectional view showing a filling gas bag 91 using the composite rubber sheet 15 according to the present invention, and FIG. 6B is a sealing gas bag using the composite rubber sheet 15 according to the present invention. FIG.

  The composite rubber sheet can increase the gas impermeability without hindering the elasticity of the rubber material. Due to this characteristic, the composite rubber sheet 15 is inflated with a gas bag 91 (FIG. 6A) for filling a gas (for example, city gas) or the like with a gas (for example, air) or the like. This can be applied to a sealing gas bag 92 (FIG. 6B) used when temporarily sealing the opening 93. These bags 91 and 92 can be formed from the composite rubber sheet 15, or the composite rubber sheet 15 can be attached to the inner surface of the bag. For example, according to the composite rubber sheet in which the laminate film 31 described above is bonded to natural rubber, the permeation of oxygen can be blocked and the aging resistance can be greatly enhanced.

  Examples of applications utilizing the gas-impermeable characteristics of composite rubber sheets include the above, packing used in fuel cells, packing for hydrogen engines, or air used to protect ship dredging and quay walls A fender of the formula can be mentioned. Pneumatic fenders must be regularly maintained to maintain internal pressure (such as supplemental gas filling), but maintenance can be performed by attaching a composite rubber sheet to the inner surface of this pneumatic fender. A free pneumatic fender can be provided.

  When utilizing the gas-impermeable characteristics, the composite rubber sheet may be applied to at least a part of the gas bags 91 and 92 and the pneumatic fender. This is because the amount of gas permeation can be relatively reduced as compared with the case where no composite rubber sheet is used.

  Examples of applications utilizing the electromagnetic wave shielding function of the composite rubber sheet include a lining material for making an electromagnetic shielding environment chamber, and a lining material for covering electronic devices.

  Examples of applications utilizing the oil resistance and chemical resistance characteristics of the composite rubber sheet include piping systems used for oil and chemicals and packing used for equipment.

  Examples of applications utilizing the decorative property of the composite rubber sheet include a panel material attached as an ornament to a wall surface, and a small piece that is cut and used as an ornament like the valve body 80 described above. When aluminum is used as the metal thin film, a composite rubber sheet having various colored surfaces can be provided by performing color alumite treatment.

  The composite rubber sheet can be easily attached to a surface having a complicated shape due to the elasticity of the base material.

It is sectional drawing which shows the composite rubber sheet which concerns on one Embodiment of this invention. It is sectional drawing which shows the composite rubber sheet which concerns on other embodiment of this invention. It is sectional drawing which shows the composite rubber sheet which concerns on other embodiment of this invention. 4A and 4B are sectional views showing a safety valve for a sealed secondary battery using the composite rubber sheet according to the present invention as a valve body. It is sectional drawing which shows the state which assembled | attached the safety valve shown by FIG. 4 to the armored can of a sealed secondary battery. 6A is a cross-sectional view showing a filling gas bag using the composite rubber sheet according to the present invention, and FIG. 6B is a cross-sectional view showing a sealing gas bag using the composite rubber sheet according to the present invention. FIG.

Explanation of symbols

11, 12, 13, 14, 15 Composite rubber sheet,
21 Base material made of rubber material,
22 Metal thin film,
23 protective layer,
31 Laminated film,
32 metal foil layer,
33 resin film layer,
40 Safety valve for sealed secondary battery,
50 exterior cans,
51 opening,
60 sealing plate,
61 vent holes,
70 terminal cap,
71 vents,
80 disc,
91 gas bag for filling,
92 Gas bag for sealing.

Claims (7)

  A composite rubber sheet obtained by bonding a metal thin film (22) to the surface of a base material (21) made of a rubber material.   The said metal thin film (22) is provided with at least 1 characteristic of gas impermeability, the function which shields electromagnetic waves, oil resistance, chemical resistance, and a decoration property, The claim 1 characterized by the above-mentioned. Composite rubber sheet.   The composite rubber sheet according to claim 1, further comprising a protective layer (23) for protecting the metal thin film (22) on a surface of the metal thin film (22).   The metal thin film (22) and the protective layer (23) are composed of a laminate film (31) obtained by pasting together a metal foil layer (32) and a resin film layer (33). The composite rubber sheet according to claim 3. A sealing plate (60) which is airtightly attached to the opening (51) of the outer can (50) and has a gas vent hole (61), and a vent hole (71) which is attached to the sealing plate (60) and is attached to the sealing plate (60). An open terminal cap (70), and a valve arranged in an elastically compressed state so as to cover the gas vent hole (61) between the sealing plate (60) and the terminal cap (70). A safety valve for a sealed secondary battery having a body (80),
The valve body (80) is composed of a composite rubber sheet formed by joining a metal thin film (22) having gas impermeability to the surface of a base material (21) made of a rubber material, and the metal thin film (22) is A safety valve for a sealed secondary battery, wherein the safety valve is arranged so as to cover the gas vent hole (61).   The safety valve for a sealed secondary battery according to claim 5, further comprising a protective layer (23) for protecting the metal thin film (22) on a surface of the metal thin film (22).   The said metal thin film (22) is comprised from the laminated film (31) which bonded together the metal foil layer (32) and the resin film layer (33), The airtight type | mold of Claim 5 characterized by the above-mentioned. Safety valve for secondary battery.

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