JP4816858B2 - Sealant composition for aqueous electrolyte battery - Google Patents

Description

  The present invention relates to a sealing agent composition particularly excellent in hermeticity at high temperatures used for aqueous electrolyte batteries, and more specifically, used in combination with a packing or gasket for sealing an aqueous electrolytic solution. It is related with the sealing agent composition made.

  In recent years, electronic devices such as digital cameras, mobile phones, laptop computers, and the like have been remarkably improved in performance and size, and there has been an increasing demand for higher capacity in batteries serving as power sources for these electronic devices. Conventionally, a manganese battery is used as a primary battery for such applications, and an alkaline battery using an alkaline electrolyte such as potassium hydroxide is frequently used as a battery capable of obtaining a larger capacity. Similarly, nickel-metal hydride batteries using an alkaline electrolyte such as potassium hydroxide are frequently used as chargeable / dischargeable secondary batteries. By the way, since the battery using this alkaline electrolyte uses a strong alkaline solution that may affect human skin or eyes as the electrolyte, it is necessary to suppress leakage of the electrolyte as much as possible. A sealing member (gasket, packing) made of nylon, polypropylene, or the like is placed on the opening of the battery can body in which the battery is incorporated to take a sealed structure. Also, if the battery has completely prevented liquid leakage, the battery internal pressure may increase due to liquid leakage from the negative electrode to the positive electrode or gas generated due to reverse loading, etc., which is another meaning. Very dangerous.

  Various proposals have been made as methods for preventing the above-described leakage of the electrolytic solution. For example, in Japanese Examined Patent Publication No. 51-6846, an opening of a metal container is sealed with an insulating sealing body such as a synthetic resin or rubber having no through hole at the center, and then a metal cathode is formed at the center of the insulating sealing body. There has been proposed a method for producing an alkaline battery in which a current collecting rod is penetrated by pressing and a cathode current collecting rod is inserted into a cathode zinc agent. Japanese Patent Publication No. 60-52542 proposes a battery packing (gasket) material comprising a mixed composition of polyethylene and ethylene-vinyl acetate copolymer. Japanese Examined Patent Publication No. 63-62068 proposes an alkaline battery in which a sealing agent obtained by adding a vinyl acetate homopolymer or a vinyl acetate copolymer to asphalt is interposed on the gasket surface. In Japanese Patent Laid-Open No. 63-202845, a sealing agent in which 5 to 15% by weight of atactic polypropylene is added to a main component mainly composed of asphalt is interposed between an insulating packing and a positive electrode terminal member and a negative electrode terminal member. Nonaqueous electrolyte batteries have been proposed. Japanese Laid-Open Patent Publication No. 63-80471 proposes improving liquid leakage resistance during storage by mixing silicon rubber with pitch (asphalt). Japanese Patent Publication No. 5-58220 proposes a battery in which a battery sealing portion is sealed with a sealing material composed of a polymer mainly composed of isobutylene having an average molecular weight of 700 to 10,000 and containing 0.5 to 10% by weight of crystalline polypropylene. . Japanese Patent Application Laid-Open No. 11-40118 proposes a sealing agent for alkaline secondary batteries whose main component is one or more rubbers selected from rubbers having saturated main chains of polymethylene type and diene rubbers. Yes. Japanese Patent Publication No. 63-1706 discloses a cationic aqueous dispersion dispersed in water together with pitch (asphalt), rubber latex (styrene butadiene rubber, butadiene rubber, chloroprene rubber, ethylene propylene rubber) and a cationic surfactant. Is used as a sealing material for batteries. Japanese Patent No. 3247840 proposes the use of a photocurable resin as a sealing material for a flat type nonaqueous battery.

On the other hand, as a technique relating to an aqueous emulsion, in JP-A-3-411144, the content of a vinyl compound copolymerized with ethylene, vinyl acetate and vinyl acetate produced using polyvinyl alcohol as an emulsion stabilizer is 1 respectively. An ethylene-vinyl acetate copolymer emulsion obtained by adding sodium polyacrylate to an ethylene-vinyl acetate copolymer emulsion of ˜45 wt%, 55 to 99 wt% and 0 to 30 wt% has been proposed. Japanese Patent Laid-Open No. 2002-302661 includes (a) 25 to 75% by weight of vinyl acetate and (b) 75 to 25% by weight of vinyl ester of α-branched aliphatic carboxylic acid having 9 to 11 carbon atoms. A moisture-proof adhesive composition obtained by emulsion polymerization of a monomer mixture using a modified polyvinyl alcohol containing 1 to 10 mol% of an α-olefin unit having 2 to 4 carbon atoms as a protective colloid has been proposed. Yes.
Japanese Examined Patent Publication 51-6846 Japanese Patent Publication No. 63-62068 JP-A-63-202845 JP-A-63-80471 Japanese Patent Publication No. 5-58220 Japanese Patent Laid-Open No. 11-40118 Japanese Examined Patent Publication No. 63-1706 Japanese Patent Publication No. 60-52542 Japanese Patent No. 3247840 Japanese Patent Laid-Open No. 3-411144

  However, the above battery sealing material is widely used for primary batteries and secondary batteries. However, in a sealing agent system in which rubber and a tar pitch agent are dissolved in an organic solvent, the organic solvent contained in the system is used. Environmental impact is a problem. In order to solve this problem, Japanese Examined Patent Publication No. 63-1706 proposes a water-based sealant, but the film properties (electrolytic solution resistance, etc.) when a sealing material layer is formed are solvent-based sealants. We have problems such as being bad in comparison. Further, in Japanese Patent No. 3247840, the problem of solvent is solved by using a photocurable resin as a sealant. However, the problem is that the sealant is expensive, the problem of low-molecular monomer vapor that occurs during photocuring, light However, there is a problem that the uncured portion remains and the resin subjected to anaerobic curing and heat curing imparts a significant decrease in physical properties such as flexibility as compared with the photocured resin. In addition, a special light irradiation device is required, resulting in an increase in production cost.

  In the present invention, in order to solve the above-mentioned problems, that is, an organic solvent is not used as a sealing agent or the use thereof is suppressed as much as possible, and various performances required for a sealing material of an aqueous electrolyte battery such as an electrolytic solution resistance are satisfied. And it aims at providing the sealing compound composition for aqueous | water-based electrolyte batteries which does not cause a raise of production cost.

As a result of intensive studies to solve the above problems, in the first invention of the present invention, (A) an aqueous emulsion of ethylene-vinyl acetate-vinyl versatate copolymer , and (B) chloroprene latex, chlorosulfonated polyethylene latex One or more selected from among styrene- (meth) acrylic emulsions was used as a sealing composition for an aqueous electrolyte battery. In particular, the aqueous electrolyte battery in which the mass blending ratio of the polymer component (solid content) of the component (A) and the component (B) is (A) component: (B) component = 10 to 90:90 to 10% by mass. The sealing agent composition for use can improve the film strength and workability in a well-balanced manner when the sealing material layer of the aqueous electrolyte battery is formed.

  The copolymer of (A) ethylene-vinyl acetate-vinyl versatate used in the sealing agent composition of the present invention has a copolymer composition ratio (ratio of segment units of each component) of ethylene-vinyl acetate: versatic acid. It is desirable that vinyl = 15-80: 85-20. Of these, the copolymer composition ratio of ethylene-vinyl acetate is preferably ethylene: vinyl acetate = 10-40: 90-60. When the copolymer composition ratio of Versatic acid is less than 20, the chemical resistance is lowered or when it is attached to the opening of the metal container (between the insulating gasket and the metal container or between the insulating gasket and the sealing body). When the sealing property is lowered and the content is higher than 85%, the strength of the formed film is lowered.

  The copolymer of (A) ethylene-vinyl acetate-vinyl versatate uses an emulsifier such as polyvinyl alcohol as a protective colloid, and the polymerization initiator, ethylene, vinyl acetate, vinyl versatate monomers in water in the above ratio The mixture can be obtained by stirring and mixing with an emulsion polymerization. Further, since the solidified product (sealing material) of the sealing agent composition of the present invention has a high possibility of coming into contact with the electrolytic solution, the properties of the sealing material are insoluble / inactive in the electrolytic solution and need to be less swollen. . Sumikaflex 950 and 951 (both manufactured by Sumitomo Chemical Co., Ltd.) can be mentioned as commercial products of the aqueous emulsion of (A) ethylene-vinyl acetate-vinyl versatate copolymer that can be used in the present invention.

In the present invention, (B) chloroprene latex, chlorosulfonated polyethylene latex, styrene- (meta) from the viewpoints of the above-mentioned (A) ethylene-vinyl acetate-vinyl versatate aqueous emulsion and film strength, electrolytic solution resistance, and workability. ) It is necessary to contain one or more acrylic emulsions. Above (A), (B) solids loading ratio of the component, the component (A): (B) Component = 10-90: 90-10 is preferred that the mass%, more preferably component (A): component (B) = 20-80: 80-20 is a mass%. Component (A): (B) Component = 0-9: adhesion 100 to 91 mass% in the resin and the member becomes much worse becomes leakage. The component (A): (B) Component = 91 - 100: 9-0 mass% in resin strength, electrolyte resistance of the resin is much leakage to decrease.

  As specific examples of the component (B), chloroprene latex may be Skyprene Latex GFL-820, GFL-890, GFL-280 (Tosoh Corp.), Shoprene 400, 650, 601A, 671A, etc. (Showa Denko Corp.) Chlorosulfonated polyethylene latex is CSM200, CSM450 (Sumitomo Seika Co., Ltd.), and styrene- (meth) acrylic emulsion is DC-130 (Dainippon Ink Chemical Co., Ltd.). Those having flexibility and adhesion with a glass transition temperature of 15 ° C. or lower are desirable.

In addition, the sealant composition of the present invention further includes an antiaging agent, an ultraviolet absorber, a colorant, an antifoaming agent, a surfactant, an antiseptic, an organic / inorganic filler, and the like that are usually used in aqueous emulsions. Agents can be added as needed. These additives are arbitrarily selected and used in consideration of the type of insulating gasket (packing) to which the sealant composition of the present invention is applied, the type of electrolytic solution, etc., but preferably do not react with the electrolytic solution. In addition, it is desirable that it does not dissolve in the electrolytic solution. For example, as the surfactant, commonly used fluorine surfactants, anionic surfactants such as alkyl sulfate esters, polyoxyethylene alkyl ethers, alkylbenzene sulfonates, polyoxyethylene alkyl ethers, sorbitans, etc. Nonionic surfactants such as fatty acid esters and polyoxyethylene sorbitan fatty acid esters, and amphoteric surfactants such as alkylbetaines, alkylbetaines, and alkylamine oxides. Examples of the preservative include organic, inorganic fillers such as polystyrene, glass powder, silica, zinc white, and alumina. In particular, when solid pigments and organic / inorganic fillers are added, it is necessary to dissolve or disperse them sufficiently uniformly in the composition. When using granulated or agglomerated structures, use a ball mill. It is better to disperse with a sand mill or ultrasonic waves. The addition amount of each additive may be any amount, but 0.01 mass% to 2 mass% in the defoaming agent to the present invention sealant composition, the colorant is 0.1 mass% to 30 mass%, the surfactant is 0.01 mass part to 5 mass%, the preservative to 5 mass parts 0.01 mass part, is an organic-inorganic filler from 0.01 to 40 mass parts .

  The aqueous electrolyte battery of the present invention is not limited as long as the sealing agent layer of the present invention described above is provided between the metal container and the insulating gasket, and the material of the metal container, the power generation element, and the insulating gasket are generally It may be used. The power generation element described above is an electrolytic solution composed of a supporting electrolyte and an aqueous electrolyte solution, an active material for a positive electrode and a negative electrode, a separator, and the like. As the aqueous electrolyte, for example, an aqueous potassium hydroxide solution or an aqueous zinc chloride solution is used. As the insulating gasket, a nylon resin and a polyolefin resin such as polyethylene, polypropylene, and ethylene / propylene copolymer, which are generally said to have high electrolytic solution resistance, are used.

  What is necessary is just to form the sealing material layer of the aqueous electrolyte battery of this invention in the following procedure, for example. That is, the sealing agent composition of the present invention is applied to the surface of a metal container and / or the surface of an insulating gasket by feeding a predetermined amount with a metering pump such as an air-driven metering dispenser, a roller pump, or a gear pump. After coating, these coatings are naturally dried or dried at low temperature while maintaining the level so that the sealant composition does not shift, and the aqueous solvent is removed to form a thin resin layer. However, the application is not limited to a method using a metering pump, and can be performed manually using a brush if the amount is small. Further, it is needless to say that drying can be performed in a short time by using a blower or the like in combination, and the process can be industrially more suitable. What is necessary is just to select the thickness of the sealing material layer provided by such a method arbitrarily with the magnitude | sizes of a metal container and an insulation gasket, and they are 0.1 micrometer-1000 micrometers normally. If the thickness of the layer is insufficient, there may be a problem of leakage of the electrolyte solution or intrusion of moisture or the like, or the layer may be cut. On the contrary, if the layer is thick, it may be difficult to form the layer.

The sealant composition for an aqueous electrolyte battery of the present invention is formed as a sealing material layer so as to be interposed between a gasket (packing) of an aqueous electrolyte battery and a battery container. In addition to preventing leakage of the liquid, it is possible to produce an aqueous electrolyte battery that is particularly excellent in hermeticity at high temperatures due to its high durability against the aqueous electrolyte.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, unless otherwise indicated, the part and% in each example are a mass reference | standard.

The sealing agent composition for aqueous | water-based electrolyte solution batteries of this invention was adjusted with the compounding ratio which shows the Example of this invention in Tables 1-3. In addition, each component used for the Example is as follows.
(A) Ethylene-vinyl acetate-versaic acid copolymer aqueous emulsion, Sumikaflex 950HQ, manufactured by Sumika Chemtex Co., Ltd., Sumikaflex 951, manufactured by Sumika Chemtex Co., Ltd. (B) component, CSM450 latex (chlorosulfonated polyethylene latex) Sumitomo Seika・ Skyprene Latex GFL820 (Chloroprene Latex) Tosoh ・ Boncoat DC-130 (Styrene- (Meth) acrylic emulsion) Dainippon Ink & Chemicals Inc. Other components ・ Sumikaflex 900H (ethylene-vinyl acetate-acrylic copolymer) Aqueous emulsion) Sumika Flex 755 (Ethylene-vinyl acetate copolymer aqueous emulsion) manufactured by Sumika Chemtex Co., Ltd. Sumikaflex 400HQ (ethylene-vinyl acetate manufactured by Sumika Chemtex Co., Ltd.) Polymer aqueous emulsion) manufactured by Sumika Chemtex Co., Ltd.

[Electrolytic solution immersion test]
Each sealing agent composition prepared in Examples 1 to 16 and Comparative Examples 1 to 11 was applied onto a polyfluorinated ethylene plate and dried and solidified at 80 ° C. until there was no weight loss of volatile components such as moisture. Next, each of the obtained dry films was peeled off from the polyfluorinated polyethylene plate and cut to obtain test pieces (width 2 cm × length 3 cm × thickness of about 300 μm).
These test pieces were immersed in a 40% potassium hydroxide aqueous solution (alkali resistance test) heated to 80 ° C. for 2 weeks. These results are also shown in Tables 1 to 3.

  From Examples 1-16, (A) component and (B) component are mix | blended in said ratio, and the resin weight change after electrolyte solution immersion at the time of forming a membrane | film | coat becomes a weight increase, but Examples 11-13 When other components were blended like this, the resin was dissolved in the electrolyte and the weight was reduced. Moreover, the ethylene vinyl acetate copolymer which does not contain a versatic acid also in the resin weight change after electrolyte solution immersion when a film is formed only by (A) component or (B) component like Comparative Examples 1-8 The resin weight decreased. Moreover, compared with Examples 1-16, compared with Examples 1-16, what mix | blended and used (A) and (B) component rather than when using (A) component or (B) component independently. Significant improvement in electrolyte resistance was observed. In particular, it can be seen that when (A) component and (B) component = 10 to 90:90:10, the leakage resistance can be remarkably improved as compared with the case where each of them is used alone.

  In addition to ethylene-vinyl acetate-acrylic copolymer aqueous emulsions and ethylene-vinyl acetate copolymer aqueous emulsions alone, when they are added in a large amount to component (A), they are resistant to alkaline electrolytes. It turns out that falls.

  The sealant composition for aqueous electrolyte batteries of the present invention can be suitably used for battery seals typified by alkaline electrolyte batteries, and also has high electrolyte resistance characteristics. It can also be applied to sealing materials such as electronic parts using the aqueous electrolyte.

Claims (2)

(A) An aqueous emulsion of ethylene-vinyl acetate-vinyl versatate copolymer , and (B) one or more selected from chloroprene latex, chlorosulfonated polyethylene latex, and styrene- (meth) acrylic emulsion. A sealant composition for an aqueous electrolyte battery characterized by the above. The mass blending ratio of the polymer component (solid content) of the component (A) and the component (B) is (A) component: (B) component = 10 to 90:90 to 10% by mass. A sealant composition for an aqueous electrolyte battery.