JP2011086534A - Gasket for nonaqueous electrolyte battery or non-aqueous electric double layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasket which can be used under an environment of high temperature or thermal shock, etc. with no occurrence of problems such as liquid leakage where the electrolyte solution inside the battery leaks outside due to inefficient sealing property in the gasket, a positive electrode can and a negative electrode can caused by unevenness in the sealing agent, and the characteristic deterioration caused when stored, and which does not have reduction in capacity or deterioration in performance in the battery using lithium. <P>SOLUTION: The gasket for nonaqueous electrolyte battery has hydroxyl group introduced to a surface of the gasket body by an oxygen plasma process that carries out plasma processing by using oxygen, has the surface of the gasket body reformed by introduced hydroxyl group and the water imparted to the surface of the gasket body by an interaction between the hydroxyl group and water molecules in the air, and has a coating layer formed on the reformed surface of the gasket body by coating the reformed surface of the gasket body with material that can form the coating layer in the presence of water. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a gasket for a non-aqueous electrolyte battery or a non-aqueous electric double layer capacitor, and more particularly, a gasket for interposing and sealing between a positive electrode can and a negative electrode can in a non-aqueous electrolyte battery or a non-aqueous electric double layer capacitor. In particular, the present invention relates to an insulating gasket used for a nonaqueous electrolyte battery or the like in which a lithium potential is applied to a negative electrode.

  In the past, aqueous secondary batteries such as lead-acid batteries and nickel / cadmium batteries were used as secondary batteries that are widely used, but these aqueous secondary batteries operate beyond the decomposition potential of water. Since the voltage could not be obtained, the energy density was low. Therefore, recently, research and development of non-aqueous electrolyte batteries represented by lithium ion secondary batteries have been actively conducted. This non-aqueous electrolyte battery has a high operating voltage, high energy density, and excellent cycle characteristics. Therefore, not only a small consumer battery with an electric capacity of about 1.5 Ah but also a recent energy saving and environment Combined with the demand for maintenance, it is expected to expand to large batteries for power storage and electric vehicles.

  However, in a non-aqueous electrolyte battery, it is necessary to strictly prevent moisture from entering the battery. Therefore, ensuring the airtightness of the battery is more important than the aqueous secondary battery. In addition, from the viewpoint of battery safety, it is necessary to prevent contact / short circuit with a member having the opposite polarity to the conductive member that conducts one electrode of the electrode group to the external current collecting terminal.

  Therefore, the material of the gasket that maintains the airtightness, liquid tightness, and electrical insulation of the positive and negative electrode cans is extremely important. As the material of the gasket, polyethylene, polypropylene, copolymers thereof, and the like that are excellent in chemical resistance, elasticity, creep resistance, good moldability, and can be manufactured at low cost are used. However, these polyethylenes and polypropylenes soften and become easily deformed according to external forces when the temperature rises, and gaskets made of such materials are resistant to high temperature environments and conditions of rapid temperature changes. There is a defect that is easy to deform. For this reason, when the battery is exposed to a high temperature environment or a sudden temperature change condition, the gasket deteriorates and deforms, the sealing function is impaired, the electrolyte inside the battery vaporizes and leaks, etc. There is also a problem in that insulation cannot be obtained and a short circuit occurs due to contact.

  Therefore, in order to solve these problems, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA) or the like is used as a material that hardly deteriorates and deforms even when used under conditions such as a high temperature environment and a rapid temperature change. Patent applications such as Patent Documents 1 to 4 below have been filed using the above-mentioned fluorine-based resin as a gasket material.

  In addition, it is not only non-aqueous electrolyte batteries as described above but also non-aqueous electric batteries that use a fluorine-based resin as a gasket material that is less likely to deteriorate and deform even when used under conditions such as high temperature environments and sudden temperature changes. This is also applied to double layer capacitors, and as such a patent application, a patent application such as the following Patent Document 5 has been filed.

  However, when a gasket made of a fluororesin is used, as described in paragraph [0007] of the specification of Patent Document 3, the fluororesin has a property of repelling a liquid sealant. As a result, the gas tightness between the gasket, the positive electrode can and the negative electrode can becomes inadequate, and the electrolyte inside the battery leaks to the outside, and the characteristics deteriorate during storage. It was.

  Furthermore, when a gasket made of a fluororesin is used, there is a problem when a lithium potential is used for the negative electrode as a nonaqueous electrolyte battery, as described in Patent Document 2 and Patent Document 4 above. . That is, paragraph [0006] of the specification of Patent Document 2 states that “the chemical reaction between lithium or lithium ions and the fluororesin is an electrochemical reaction, and in order for the chemical reaction to occur, the fluororesin must be lithium or lithium. It is necessary to be in contact with ions and to supply electrons to the surface of the fluororesin, so that the chemical reaction in the battery can supply electrons, and the contact surface between the negative electrode can of the battery and the fluororesin Further, paragraph [0006] of the specification of Patent Document 4 describes that “the lithium in the battery and the fluorine-based resin react to consume the lithium in the battery, and the capacity of the battery. Will be reduced. "

JP 2001-185226 A JP 2002-56827 A JP 2002-56828 A JP 2002-198017 A JP-A-2005-64435

  The present invention has been made to solve such problems, and can be used in high-temperature environments, thermal shocks, etc., and the sealant can be uneven and the gasket, the positive electrode can, and the negative electrode can Airtightness becomes insufficient, and there is no problem of leakage of electrolyte inside the battery or deterioration of characteristics during storage, and in batteries using lithium. It is an object of the present invention to provide a gasket that does not cause capacity reduction or performance deterioration.

  In order to solve such problems, the present invention is a gasket made of a fluorine-based resin for insulating a positive electrode and a negative electrode of a non-aqueous electrolyte battery or a non-aqueous electric double layer capacitor, the gasket main body A hydroxyl group is introduced into the surface of the gasket by an oxygen plasma treatment in which oxygen is used for the plasma treatment, and the introduced hydroxyl group and the water imparted to the surface of the gasket body by the interaction between the hydroxyl group and water molecules in the air. The surface of the gasket body was modified, and a material capable of forming a coating layer in the presence of water was applied to the surface of the modified gasket body to form the coating layer on the surface of the gasket body. A gasket for a non-aqueous electrolyte battery or a non-aqueous electric double layer capacitor is provided.

  In this case, as a material that can form the coating layer in the presence of water, for example, a resin that is polymerized by reaction with water is used. Examples of the resin that polymerizes in the presence of water include, for example, a two-component polyurethane resin using isocyanate as a curing agent.

  The present invention, as described above, is a gasket made of a fluorine-based resin for insulating between the positive electrode and the negative electrode of a non-aqueous electrolyte battery or a non-aqueous electric double layer capacitor. A hydroxyl group is introduced by oxygen plasma treatment in which plasma treatment is performed using water, and water introduced to the surface of the gasket body by the interaction between the introduced hydroxyl group and the water molecules in the hydroxyl group. Since the surface is modified, water is present in the vicinity of the surface of the gasket body, and in such a state, a material capable of forming a coating layer in the presence of water is applied to the surface of the gasket body. Thus, the coating layer is formed by forming the material into a film, curing, or the like.

  For example, if a resin monomer that polymerizes in the presence of water is added, a polymerization reaction of the resin monomer occurs, whereby the polymerized resin is applied to the surface of the gasket body as a coating layer. It is. For example, if a two-component polyurethane using isocyanate is used, a polyurethane coating film is formed on the surface of the gasket body.

  As a result, the material forming the surface layer is formed by the presence of the hydroxyl group introduced into the surface of the gasket body by the oxygen plasma treatment as described above, and the water present in the interaction with the hydroxyl group, thereby interposing the gasket body. It is in a state of being strongly adhered to the surface of the.

  Therefore, even if a fluorine-based resin having a property of repelling a liquid sealant, such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), is used as a gasket material, a paint is applied to the surface of such a gasket. There is an effect that it is possible to suitably form a coating layer such as the above.

  As a result, the sealing agent becomes uneven and the gasket, the positive electrode can, and the negative electrode can have insufficient airtightness, and the electrolyte inside the battery leaks to the outside, and the characteristics deteriorate during storage. The conventional problem can be solved.

  In addition, since the surface layer as described above can be formed on the surface of the gasket body, even when a lithium battery is used as the non-aqueous electrolyte battery, the lithium inside the battery reacts with the fluorine resin, and the battery The problem that the internal lithium is consumed and the battery capacity is reduced can also be solved. Furthermore, an internal short circuit due to carbon generated by this reaction can also be prevented.

  Furthermore, the material for forming the coating layer includes the hydroxyl group introduced into the surface of the gasket body by the oxygen plasma treatment as described above, and the water present in the interaction with the hydroxyl group, thereby interposing the gasket body. Since it is in a state of being strongly bonded to the surface, there is an effect that the coating layer is not likely to be inadvertently peeled off from the surface of the gasket body.

Sectional drawing of the nonaqueous electrolyte battery as one Embodiment. Sectional drawing of the gasket attached to the nonaqueous electrolyte battery of FIG. Sectional drawing which shows the structure of the nonaqueous electrolyte battery as other embodiment. Sectional drawing of the state which decomposed | disassembled the nonaqueous electrolyte battery of FIG. Sectional drawing which shows the structure of the non-aqueous electric double layer capacitor as other embodiment.

  As described above, the gasket for a nonaqueous electrolyte battery or nonaqueous electric double layer capacitor of the present invention is a fluorine for interposing and sealing between the positive electrode and the negative electrode of the nonaqueous electrolyte battery or nonaqueous electric double layer capacitor. A gasket made of a resin, wherein hydroxyl groups are introduced into the surface of the gasket body by oxygen plasma treatment using oxygen, and the introduced hydroxyl groups and the hydroxyl groups and water molecules in the air The surface of the gasket body is modified by water applied to the surface of the gasket body by the action, and a material capable of forming a coating layer in the presence of water is applied to the surface of the modified gasket body. A coating layer is formed on the surface of the gasket body.

  The kind of the fluorine resin constituting the gasket of the present invention is not particularly limited, and chlorotrifluoroethylene ethylene copolymer (ECTFE), tetrafluoroethylene hexafluoropropylene perfluoroalkyl vinyl ether copolymer (EPE), Tetrafluoroethylene ethylene copolymer (ETFE), tetrafluoroethylene hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoro Examples include ethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluorolide (PVF), etc., especially tetrafluoroethylene perfluoroalkyl vinyl ether. It is desirable to use a polymer (PFA).

  As a more specific structure of the nonaqueous electrolyte battery, for example, a negative electrode can constituting a battery lid, a positive electrode can constituting a battery case, a negative electrode accommodated in the negative electrode can, and accommodated in the positive electrode can And a separator that partitions the negative electrode and the positive electrode. The gasket is interposed between the end portions of the negative electrode can and the positive electrode can, the end portions are sealed, and the negative electrode and the positive electrode are insulated.

  The material of the negative electrode can is not particularly limited, but in addition to stainless steel, nickel, copper, titanium, aluminum, tungsten, gold, platinum, baked carbon, etc., the surface of copper or stainless steel is treated with carbon, nickel, titanium or silver. An Al—Cd alloy or the like is used. Further, the type and production method of the electric insulation layer of the negative electrode can are not particularly limited, and it is produced, for example, by a compound layer formed by anodic oxidation, anodizing, etc., application of an electric insulation resin, or the like.

  The material of the positive electrode can is not particularly limited, and stainless steel, nickel, copper, titanium, aluminum, tungsten, gold, platinum, or the like can be used.

  As the positive electrode, manganese oxide or lithium-containing manganese oxide can be used when reflow soldering is not performed. When performing reflow soldering, titanium oxide, lithium-containing titanium oxide, molybdenum oxide, manganese oxide, vanadium oxide, niobium oxide, lithium-containing manganese oxide, lithium-containing cobalt oxide, lithium-containing nickel oxide Products, lithium-containing manganese cobalt oxide, lithium-containing manganese nickel oxide, lithium-containing cobalt nickel oxide, lithium-containing manganese cobalt nickel oxide, and the like can be used.

As the negative electrode, lithium alloy such as lithium metal or lithium-aluminum can be used when reflow soldering is not performed. When performing reflow soldering, lithium-doped carbon, lithium-doped metal oxide (SiO, WO ₂ , WO ₃ etc.), lithium-containing titanium oxide (Li ₄ Ti ₅ O ₁₂ etc.), molybdenum dioxide, Niobium oxide or the like can be used.

Since the battery voltage is determined by the combination of the positive and negative electrodes, some materials can be used as both the positive electrode and the negative electrode. Effective when combined with a gasket using a fluororesin when an active material with a relatively high potential, such as lithium-containing titanium oxide (Li ₄ Ti ₅ O ₁₂ etc.), molybdenum dioxide, niobium oxide, etc. is used for the negative electrode It is. This is because the potential of the gasket surface in contact with the negative electrode can does not drop to the lithium deposition potential, and the reaction between the fluororesin and lithium is unlikely to occur.

  The type of the electrolyte is not particularly limited, and a nonaqueous solvent used for a general nonaqueous electrolyte battery or a nonaqueous electric double layer capacitor is used. As the non-aqueous solvent, cyclic esters, chain esters, cyclic ethers, chain ethers and the like are used. Specifically, propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC ), Vinylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), γ-butyrolactone (γBL), 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane (DME) ), 1,2-ethoxyethane, diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, tetraethylene glycol dialkyl ether, dipropyl carbonate, methyl ethyl Carbonate, methylbutyl carbonate, methylpropyl carbonate, ethylbutyl carbonate, ethylpropyl carbonate, butylpropyl carbonate, propionic acid alkyl ester, malonic acid dialkyl ester, acetic acid alkyl ester, tetrahydrofuran (THF), alkyltetrahydrofuran, dialkylalkyltetrahydrofuran, alkoxy Tetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, 1,4-dioxolane, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile , Nitromethane, methyl formate, methyl acetate, methyl propionate, Propionic acid ethyl phosphotriester, maleic anhydride, sulfolane, 3-methyl sulfolane nonaqueous solvent and derivatives and mixtures of such like.

  As the separator, an electrically insulating film having a high ion permeability and a predetermined mechanical strength is used. In reflow soldering, glass fibers can be used most stably, but resins such as polyphenylene sulfide, polyethylene terephthalate, polyamide, polyimide having a heat distortion temperature of 230 ° C. or higher can also be used. A microporous film of polyethylene or polypropylene, a nonwoven fabric made of polypropylene, or the like can also be used. Furthermore, a ceramic porous body can also be used.

  Furthermore, in the present invention, as described above, the oxygen plasma treatment conditions for performing oxygen plasma treatment on the surface of the gasket main body vary depending on the type of apparatus used, but the discharge output is 0.7 to 1.5 kW. The pressure is preferably 0.2 to 0.5 Pa. Moreover, although the temperature and processing time when performing oxygen plasma processing are not specifically limited, it is preferable that temperature is 20-40 degreeC and it is preferable that processing time is 20-40 minutes.

  In such oxygen plasma treatment, hydroxyl groups are introduced on the surface of the gasket body. And as a result of introducing a hydroxyl group into the surface of the gasket body in this way, water is present in the vicinity of the surface of the gasket body due to an interaction such as hydrogen bonding with the hydroxyl group.

  In this case, water molecules present in the air are present in the vicinity of the surface of the gasket body due to interaction such as hydrogen bonding with the hydroxyl group, and thereby the surface modification of the gasket body is performed. Become.

  When forming the coating layer, by applying the material for forming the coating layer in a state where water is applied to the vicinity of the surface of the gasket body as described above, the material is caused by the interaction between the material and water. A coating layer made of can be formed. The term “application” in this case is meant to include a wide range of cases where, for example, application is performed by spraying in addition to application in a narrow sense to be applied.

  The coating layer is made of a resin that polymerizes in the presence of water, for example. Examples of the resin that is polymerized in the presence of water in this case include a two-component polyurethane using isocyanate. By adding a resin monomer that polymerizes in the presence of water, a polymerization reaction of the resin monomer occurs, and as a result, the polymerized resin is applied to the surface of the gasket body as a paint or adhesive. Thus, a coating layer is formed.

  For example, in the case of polyurethane, water is involved in the isocyanate constituting the polyurethane. That is, it is assumed that water present on the surface of the gasket main body is involved in the reaction process for obtaining the polyisocyanate prepolymer as described above.

  When polyurethane is used, examples of the polymer polyol of the polyurethane include polyester polyol, polyether polyol, polycarbonate polyol, polyester polycarbonate polyol, polyolefin polyol, conjugated diene polymer polyol, castor oil polyol, silicone polyol, vinyl Polymeric polyols and the like can be used. One type of these polymer polyols may be used, or two or more types may be used in combination.

  Furthermore, as the isocyanate of polyurethane, for example, butylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, phenylene diisocyanate, xylene diisocyanate, naphthylene diisocyanate, and the like can be used.

  Furthermore, in the case of using such a two-component polyurethane, there is an advantage that the surface activity of the two-component polyurethane can be more reliably maintained by applying a thin one-component paint as a pretreatment. Specifically, for example, a one-component paint in which an ABS resin is dissolved in a thinner (solvent) is pre-coated with a thickness of 20 μm or less to maintain surface activity, and a two-component curable paint is applied on the upper side. As a result, the ABS resin layer pretreated with the solvent is dissolved and mixed with the two-component curable coating applied on the upper side to directly react with the substrate.

  Hereinafter, more specific embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
This embodiment is an embodiment in which a gasket is attached to a nonaqueous electrolyte battery. The nonaqueous electrolyte battery of this embodiment is a coin type. In the present embodiment, as shown in FIG. 1, a negative electrode can 1 constituting a battery lid and a positive electrode can 2 constituting a battery case are provided, and a negative electrode 3 is formed in the negative electrode can 1. A positive electrode 4 is accommodated in the positive electrode can 2 while being accommodated. The negative electrode 3 and the positive electrode 4 are partitioned by a separator 5.

  The gasket 6 is interposed between the ends of the negative electrode can 1 and the positive electrode can 2 as described above, and the gap between the ends of the negative electrode can 1 and the positive electrode can 2 is sealed by the gasket 6, and the negative electrode 3 and the positive electrode 4. The space is insulated. A positive electrode current collector 7 is interposed between the positive electrode 4 and the positive electrode can 2.

  As shown in FIG. 2, the gasket body 6 a of the gasket 6 has an annular shape in which both sides are formed in a substantially L-shaped cross section, and as shown in FIG. 1, between the end portions of the negative electrode can 1 and the positive electrode can 2. Is inserted in a crimped state. Since it is interposed in a crimped state, the gasket 6 made of a fluororesin, which is an elastic member, is deformed as shown in the figure, and the gap between the ends of the negative electrode can 1 and the positive electrode can 2 is sealed by the gasket 6 It will be sealed in the state.

  As described above, hydroxyl groups are introduced into the gasket body 6a by oxygen plasma treatment using oxygen to the surface of the gasket body 6a, and the introduced hydroxyl groups and the hydroxyl groups and water molecules in the air are introduced into the gasket 6 as described above. A material capable of modifying the surface of the gasket body 6a with water applied to the surface of the gasket body 6a by interaction, and forming a coating layer on the surface of the modified gasket body in the presence of water. It has a configuration in which a coating layer is formed on the surface of the gasket body by coating.

(Embodiment 2)
In the present embodiment, the configuration of the nonaqueous electrolyte battery is different from that of the first embodiment. That is, the nonaqueous electrolyte battery according to the present embodiment is not a coin-type battery as in the first embodiment, but is formed into a square tube shape as a whole, and has a bottomed square tube shape with an open top surface. The battery case 1 has a configuration in which an electrode body and a non-aqueous electrolyte (not shown) are loaded, and the upper surface of the battery case 1 is closed by a sealing means. The battery case 1 also serves as an output terminal on the positive electrode side.

Although not shown, the electrode body in the battery case 1 includes a positive electrode using a lithium salt such as lithium cobaltate (LiCoO ₂ ) as an active material, and a negative electrode using a carbon material capable of inserting and extracting lithium ions as an active material. And a separator interposed between the positive electrode and the negative electrode. As the nonaqueous electrolytic solution, for example, a solution obtained by dissolving LiPF ₆ in a solvent obtained by mixing ethylene carbonate (EC) and methyl ethyl carbonate (MEC) can be used.

  The sealing means includes a lid 7 for closing the upper surface of the battery case 1, a gasket 6 disposed on the outer surface side of the lid 7, an insulating plate 10 disposed on the inner surface side of the lid 7, and a gasket for the lid 7. 6 and a negative electrode side output terminal (negative electrode terminal) 11 that is caulked and fixed via an insulating plate 10, and a pressing plate 12 that is disposed below the insulating plate 10.

  A terminal mounting hole 13 is formed in the lid 7, and the negative electrode terminal 11 is fitted into the terminal mounting hole 13 through the gasket 6. The negative electrode terminal 11 includes a head portion 14 exposed on the upper surface of the lid 7, a tapered portion 15 on the lower surface side of the head portion 14, and a shaft portion 16 protruding below the tapered portion 15. A cylindrical portion 18 having an insertion hole 17 through which the shaft portion 16 of the terminal 11 is inserted, and a flange portion 19 provided on the outer periphery of the upper end of the cylindrical portion 18 and interposed between the head portion 14 of the negative electrode terminal 11 and the lid 7. And.

  The outer diameter dimension of the upper end side of the taper portion 15 of the negative electrode terminal 11 is set larger than the inner diameter dimension of the upper end opening of the insertion hole 17 of the gasket 6, thereby caulking the negative electrode terminal 11 by compression in the vertical direction. The outer peripheral surface of the taper portion 15 is brought into close contact with the peripheral edge of the upper end opening of the insertion hole 17 of the gasket 6 so as to be in a state of being pressed and crushed obliquely downward.

  As described above, the gasket 6 according to the present embodiment also introduces hydroxyl groups into the surface of the gasket body 6a by oxygen plasma treatment using plasma with oxygen, the introduced hydroxyl groups, and water molecules in the air and the hydroxyl groups. The surface of the gasket body 6a can be modified with water applied to the surface of the gasket body 6a by the interaction with the surface of the gasket, and a coating layer can be formed on the surface of the modified gasket body in the presence of water. A material is applied, and a coating layer is formed on the surface of the gasket body.

(Embodiment 3)
This embodiment is an embodiment showing an example in which the gasket 6 is applied to a non-aqueous electric double layer capacitor. In the non-aqueous electric double layer capacitor of this embodiment, a separator 22 impregnated with an electrolytic solution is interposed between a negative electrode 20 and a positive electrode 21, and a negative electrode can 23 constituting a lid and a positive electrode can 24 constituting a case. The negative electrode 20 is connected to the negative electrode can 23 via a negative electrode current collector 25, and the positive electrode 21 is connected to the positive electrode can 24 via a positive electrode current collector 26.

  The positive electrode can 24 is caulked and sealed in a state in which the negative electrode can 23 is electrically insulated via the gasket 6 to constitute an electric double layer capacitor.

  As described above, the gasket 6 according to the present embodiment also introduces hydroxyl groups into the surface of the gasket body 6a by oxygen plasma treatment using plasma with oxygen, the introduced hydroxyl groups, and water molecules in the air and the hydroxyl groups. The surface of the gasket body 6a can be modified with water applied to the surface of the gasket body 6a by the interaction with the surface of the gasket, and a coating layer can be formed on the surface of the modified gasket body in the presence of water. A material is applied, and a coating layer is formed on the surface of the gasket body.

  Examples of the present invention will be described below.

Example 1
In this example, a sheet made of tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA) (hereinafter referred to as PFA sheet) was used as a gasket sample.

  The surface of the PFA sheet prepared in this way was subjected to oxygen plasma treatment. In this oxygen plasma treatment step, a vacuum deposition apparatus (SIP 1600F [manufactured by Showa Vacuum Co., Ltd.]) was used. The discharge output in the oxygen plasma treatment step was 1 kW, and the pressure was 0.35 Pa. Further, the temperature during the oxygen plasma treatment was 30 ° C., and the treatment time was 30 minutes.

  Such oxygen plasma treatment introduces hydroxyl groups to the surface of the PFA sheet, and the interaction between the introduced hydroxyl groups and water molecules in the air can impart water to the surface of the PFA sheet as described above. In this example, by exposing the PFA sheet treated with oxygen plasma as described above to the air for 5 minutes or more, water molecules in the air interact with hydroxyl groups introduced on the surface of the PFA sheet, Was able to be given.

  In the subsequent surface layer forming step, a polyester urethane coating is applied to the surface of the modified PFA sheet that has been given water by the oxygen plasma treatment and the interaction between the hydroxyl groups introduced by the treatment and water molecules. did. As the polyester urethane coating, a two-component polyester urethane coating (SF6062A-N Fujikura Kasei Co., Ltd.) using an isocyanate curing agent was used. As a result, a coating film of polyester urethane coating was suitably applied to the surface of the PFA sheet. This is probably because the isocyanate and the polyester polyol were polymerized in the presence of the water imparted in the water imparting step, so that the polyester urethane coating was applied.

  As a result, the polyester urethane coating was applied to the PFA sheet in such a strong state that it would not be inadvertently peeled off.

(Test Example 1)
In this test example, the reactivity of the sample of the PFA sheet obtained by forming a coating film on the PFA sheet as in Example 1 and the lithium piece was tested.

Four types (1 μm, 5 μm, 10 μm, 20 μm) of samples having different coating film thicknesses were prepared as in Example 1 above. These four types of PFA sheet samples were brought into contact with metallic lithium in an electrolytic solution in which LiPF ₆ was dissolved at a concentration of 1 mol / l as an electrolyte in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC). The change when left for 48 hours was observed. On the other hand, a PFA sheet on which no coating film was formed was prepared as a comparative example. Similarly, changes were observed when the plate was contacted with metallic lithium in the electrolytic solution and allowed to stand at room temperature for 48 hours. The results are shown in Table 1.

  As is clear from Table 1, in the PFA sheet in which the coating film was not formed, the blackening considered to be caused by carbon generated by the reaction between the PFA sheet and lithium metal was observed. On the other hand, in the PFA sheet with the coating film formed, it was recognized that the PFA sheet and lithium metal were separated from each other without being affected by the electrolyte solution for any of the four types of thickness. No blackening due to the carbon produced in the reaction was observed.

(Test Example 2)
In this test example, the wettability of the four types of coating film-formed PFA sheets having different film thicknesses used in Test Example 1 was evaluated.

  The sample of the PFA sheet was immersed in a 10% asphalt solution (solvent / toluene) to attach the asphalt to the surface and dried on a wire mesh. The results are shown in Table 2. As is clear from Table 2, the asphalt used as the sealant must be uniformly distributed, but in the PFA sheet that does not form a coating film, the asphalt that adheres due to the repelling phenomenon due to PFA adheres in a dew-like manner. Only a uniform seal layer was not formed. In contrast, in the PFA sheet on which the coating film was formed, a uniform sealing layer was formed for any of the four types of thickness.

3 Gasket

Claims (3)

  An insulating gasket composed of a fluorine-based resin for insulating a positive electrode and a negative electrode of a non-aqueous electrolyte battery or a non-aqueous electric double layer capacitor, and the surface of the gasket body is subjected to plasma treatment using oxygen. Hydroxyl group is introduced by oxygen plasma treatment, and the surface of the gasket body is modified by water introduced to the surface of the gasket body by the interaction between the introduced hydroxyl group and water molecules in the hydroxyl group and air, A non-aqueous electrolyte battery or a non-aqueous electrolyte battery, wherein a material capable of forming a coating layer in the presence of water is applied to the surface of the modified gasket body to form a coating layer on the surface of the gasket body. Gasket for hydroelectric double layer capacitor.   The gasket for a non-aqueous electrolyte battery or a non-aqueous electric double-layer capacitor according to claim 1, wherein the material capable of forming a coating layer in the presence of water is a resin that polymerizes by reacting with water.   The gasket for a non-aqueous electrolyte battery or non-aqueous electric double layer capacitor according to claim 2, wherein the resin that reacts with water and polymerizes is a two-component polyurethane resin using isocyanate as a curing agent.

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