JP2009252719A - Packing for insulation seal of lithium-ion secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packing for an insulation seal of a lithium secondary battery. <P>SOLUTION: This is the packing for the insulation seal of the lithium-ion secondary battery composed of an adhesive fluororesin having carbonyl group in which the adhesive fluororesin contains (a) repeating units based on tetrafluoroethylene and/or chlorotrifluoroethylene, (b) repeating units based on cyclic hydrocarbon monomer having acid anhydride group and having polymerizable unsaturated group in the ring, and (c) repeating units based on other fluorine-containing monomers (wherein tetrafluoroethylene and chlorotrifluoroethylene are excluded). This is composed of the fluorine-containing copolymers or the like in which against the total mole amount of the repeating units (a), (b), and (c), repeating units (a) have 50 to 99.89 mol%, repeating units (b) 0.01 to 5 mol%, and repeating units (c) 0.1 to 49.99 mol%, while capacity flow velocity is 0.1 to 1,000 mm<SP>3</SP>/second. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an insulating seal packing for a lithium ion secondary battery and an insulating seal method for a lithium ion secondary battery using the same.

  In recent years, lithium-ion secondary batteries are high-voltage, high-capacity, high-power storage batteries that can be reduced in size and weight, and are integrated video cameras, CD players, MD players, personal computers, portable information terminals, It attracts attention as a power source for cordless portable electronic devices such as mobile phones. Further, by utilizing the characteristics of high capacity and high output, it has been developed in the fields of secondary batteries such as hybrid cars and electric cars, and stationary solar batteries and windmills.

  An example of the structure of the electrolytic solution and the electrical insulating portion of these lithium ion secondary batteries is shown in FIG. In this example, a positive electrode plate A is formed by applying a material containing a lithium composite oxide as a positive electrode active material to an aluminum foil as a positive electrode current collector, and a negative electrode active material is applied to a copper foil as a current collector. A material containing carbon is applied to form a negative electrode plate B, and a separator C is interposed between them as a separator C. A film made of polyethylene, polypropylene, cellulose, an inorganic material, a porous body, a cloth, or the like is interposed between the electrodes. The laminated body 11 is accommodated in a cylindrical battery can 12 serving as a negative electrode terminal, and a lithium ion secondary battery is manufactured as a completely sealed structure using the insulating seal packing 14, the sealing body (positive electrode terminal) 13, and the like.

  The lithium ion secondary battery is designed so that energy can be stored and extracted more safely in the form of ions. However, if lithium metal is deposited on the negative electrode side due to overcharge or the oxidation state of the positive electrode is increased, it is not possible. It may become stable. Further, if cobalt of the positive electrode is eluted by overdischarge or copper of the current collector of the negative electrode is eluted, the secondary battery does not function. Further, when the can is bent by an external force, a short circuit occurs within the battery, and the organic solvent contained in the electrolyte may volatilize due to a rapid rise in temperature, which may cause a fire accident.

  In addition, from the viewpoint of electrical insulation and electrolyte sealing, the sealing material for the electrode terminal and lid is excellent in elasticity, chemical resistance, heat resistance, mechanical strength, moldability, etc. Resin and rubber are used. Specific examples of the material include olefin resins such as polyethylene and polypropylene, fluorine-containing elastomers such as FKM and FFKM, and fluorine resins such as PTFE, PFA, FEP, ETFE, and PVDF. However, due to the effects of external pressure, vibration, etc. on the can body over a long period of time, the temperature rises, and the fastening member of the current collecting terminal, which is a collection of electrode terminals made of metal material, the lid of the battery can, the flange part The electrolyte may leak out from the gap. These problems should be solved in terms of safety and reliability.

Japanese Laid-Open Patent Publication No.7-169452 Japanese Patent Laid-Open No. 11-213983 Japanese Patent Laid-Open No. 10-334875

  The object of the present invention is to solve the problems of the prior art, and is excellent in adhesiveness with metal members such as fastening members, lids, flanges, etc., and prevents leakage of electrolyte, It is an object to provide an insulating seal packing for a lithium ion secondary battery and an insulating seal method for a lithium ion secondary battery using the same.

The present invention provides an insulating seal packing for a lithium ion secondary battery having the following configuration and an insulating seal method for a lithium ion secondary battery using the same.
[1] An insulating seal packing for a lithium ion secondary battery, comprising an adhesive fluororesin having a carbonyl group.
[2] The lithium ion 2 according to [1], wherein the carbonyl group contained in the adhesive fluororesin is at least one selected from the group consisting of an acid anhydride group, a carboxyl group, an acid halide group, and a carbonate group. Packing for secondary battery insulation seal.
[3] The adhesive fluororesin having a carbonyl group is a fluorine-containing copolymer obtained by copolymerizing a fluorine-containing monomer and a monomer having a carbonyl group and having a polymerizable unsaturated bond. [1] A packing for insulating seals of lithium ion secondary batteries according to [2].

[4] The adhesive fluororesin having the carbonyl group is (a) a repeating unit based on tetrafluoroethylene and / or chlorotrifluoroethylene, (b) an acid anhydride group and polymerizable unsaturated in the ring A repeating unit based on a cyclic hydrocarbon monomer having a group and a repeating unit based on (c) other fluorine-containing monomer (excluding tetrafluoroethylene and chlorotrifluoroethylene), and the repeating unit (a) The repeating unit (a) is 50 to 99.89 mol% with respect to the total molar amount of the repeating unit (b) and the repeating unit (c), and the repeating unit (b) is 0.01 to 5 mol%, the repeating unit (c) is 0.1 to 49.99 mol%, and the volume flow rate is 0.1 to 1000 mm ^3. Packing for insulating seals of lithium ion secondary batteries according to [2] or [3], which is a fluorine-containing copolymer that is / sec.

[5] The cyclic hydrocarbon monomer having an acid anhydride group and having a polymerizable unsaturated group in the ring comprises itaconic anhydride, citraconic anhydride and 5-norbornene-2,3-dicarboxylic anhydride. The packing for insulating seals of the lithium ion secondary battery according to [4], which is at least one selected from the group.
[6] The other fluorine-containing monomer is vinylidene fluoride, hexafluoropropylene, CF ₂ = CFOR ^f1 (where R ^f1 is a perfluoroalkyl group having 1 to 10 carbon atoms and optionally containing an etheric oxygen atom). And CH ₂ = CX ³ (CF ₂ ) _q X ⁴ (wherein X ³ and X ⁴ are each independently a hydrogen atom or a fluorine atom, q is an integer of 2 to 10). The packing for insulation sealing of the lithium ion secondary battery in any one of [3]-[5] which is at least 1 sort (s) chosen from these.

[7] The fluorine-containing copolymer further contains a repeating unit based on (d) a non-fluorine monomer (excluding the cyclic hydrocarbon monomer), and the repeating unit (a) and the repeating unit (b ) And the lithium ion secondary battery according to any one of [3] to [6], wherein the content ratio of the repeating unit (d) is 5 to 90 mol% with respect to the total number of moles of the repeating unit (c). Insulation seal packing.
[8] The insulating seal packing for a lithium ion secondary battery according to [7], wherein the non-fluorine monomer is at least one selected from the group consisting of ethylene, propylene, and 2-methylpropylene.

[9] A method for insulating and sealing a lithium ion secondary battery using the insulating seal packing for a lithium ion secondary battery according to [1] to [8] above, wherein the method is performed at 200 to 600 ° C. in an oxygen-containing atmosphere. The surface of the metal member to be sealed with the packing is preheated, and then a primer is applied to the surface to form a primer layer, and then the packing is melt bonded to the primer layer. Insulating sealing method for lithium ion secondary battery.
[10] The insulation sealing method for a lithium ion secondary battery according to [9], wherein the metal in the metal member is at least one selected from the group consisting of aluminum, copper, nickel, and stainless steel.
[11] The method for insulating sealing a lithium ion secondary battery according to [9] or [10], wherein the shape of the metal member is a fastening member, a lid, or a flange member.

  The packing for insulating seal of the lithium ion secondary battery of the present invention is excellent in elasticity, chemical resistance, heat resistance, mechanical strength, molding processability, etc., and adhesion to the metal member of the lithium ion secondary battery In addition, since the sealing performance of the fastening member, the lid of the battery can, and the gap between the flanges is remarkably excellent, leakage of the electrolyte can be prevented over a long period of time. According to the insulating seal method for a lithium ion secondary battery using the insulating seal packing for the lithium ion secondary battery of the present invention, it is possible to prevent electrolyte leakage over a long period of time.

The packing for insulating seals of the lithium ion secondary battery of the present invention is made of an adhesive fluororesin having a carbonyl group.
The carbonyl group contained in the adhesive fluororesin is preferably a functional group such as acid anhydride, dicarboxylic acid, carboxylic acid, ester, aldehyde, carboxylic acid halide, carbonate, etc., and acid anhydride group, carboxyl group, acid halide group And at least one selected from the group consisting of carbonate groups is more preferred, and acid anhydride groups are most preferred.
The content of the carbonyl group in the adhesive fluororesin is preferably 10 to 50000 per 10 ⁶ carbon atoms in the adhesive fluororesin, more preferably 50 to 30000, and most preferably 100 to 10000.

Examples of the method for introducing the functional group containing a carbonyl group include a method of copolymerizing a fluorine-containing monomer such as tetrafluoroethylene and a monomer having a carbonyl group and having a polymerizable unsaturated bond, and polymerization having a carbonyl group Polymerization method for monomers such as tetrafluoroethylene using an initiator, fluorinated monomer such as tetrafluoroethylene using a chain transfer agent having a carbonyl group and a polymerization method, having a carbonyl group using peroxide or ionizing radiation, etc. And a method of graft polymerization of a monomer having a polymerizable unsaturated bond onto a fluororesin. A method of copolymerizing a fluorine-containing monomer such as tetrafluoroethylene and a monomer having a carbonyl group and having a polymerizable unsaturated bond is preferable.
Examples of the monomer having a carbonyl group and having a polymerizable unsaturated bond include itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid, and 5-norbornene-2,3. -Dicarboxylic acid anhydride, acid anhydrides represented by the following formulas (1) to (3), maleic acid, maleic anhydride and the like.

Examples of the monomer having a carbonyl group and having a polymerizable unsaturated bond include itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid and 5-norbornene-2,3. -More preferably, it is at least one selected from the group consisting of dicarboxylic acid anhydrides.

  In the present invention, the adhesive fluororesin having a carbonyl group includes (a) a repeating unit based on tetrafluoroethylene and / or chlorotrifluoroethylene, (b) an acid anhydride group and a polymerizable non-polymerizable ring. A repeating unit based on a cyclic hydrocarbon monomer having a saturated group and (c) a repeating unit based on other fluorine-containing monomer (excluding tetrafluoroethylene and chlorotrifluoroethylene), and the repeating unit (a ), The repeating unit (a) is 50 to 99.89 mol%, and the repeating unit (b) is 0.01% with respect to the total molar amount of the repeating unit (b) and the repeating unit (c). The fluorine-containing copolymer having a repeating unit (c) of 0.1 to 49.99 mol%. It is preferred.

  As the adhesive fluororesin, the repeating unit (a) is 50 to 99.89 mol% with respect to the total molar amount of the repeating unit (a), the repeating unit (b), and the repeating unit (c). More preferably, the unit (b) is 0.01 to 5 mol% and the repeating unit (c) is 0.1 to 49.99 mol%. When the mol% of the repeating unit (a), the repeating unit (b), and the repeating unit (c) are within the above ranges, the adhesive fluororesin has heat resistance, chemical resistance, adhesiveness, Excellent formability and mechanical properties.

Furthermore, as an adhesive fluororesin, a repeating unit (a) is 60-99.45 mol%, a repeating unit (b) is 0.05-3 mol%, and a repeating unit (c) is 0.5. More preferably, the repeating unit (a) is 80 to 98.9 mol%, the repeating unit (b) is 0.1 to 1 mol%, and the repeating unit (c). Is most preferably 1 to 19.9 mol%. The content ratio of the repeating unit is selected so that the total mol% of the repeating unit (a), the repeating unit (b), and the repeating unit (c) is 100 mol%.

In the present invention, the adhesive fluororesin further contains a repeating unit based on (d) a non-fluorine monomer (excluding the cyclic hydrocarbon monomer), and the repeating unit (a) and the repeating unit. It is more preferable that the fluorine-containing copolymer has a repeating unit (d) content of 5 to 90 mol% with respect to the total number of moles of (b) and the repeating unit (c). The content of the repeating unit (d) is more preferably 10 to 80 mol%, particularly preferably 20 to 60 mol%.
Examples of the cyclic hydrocarbon monomer having an acid anhydride group and having a polymerizable unsaturated group in the ring (hereinafter referred to as AM monomer) include itaconic anhydride, citraconic anhydride and 5-norbornene-2,3- More preferably, it is at least one selected from the group consisting of dicarboxylic acid anhydrides.

In the present invention, as the other fluorine-containing monomer (excluding tetrafluoroethylene and chlorotrifluoroethylene), vinyl fluoride, vinylidene fluoride, trifluoroethylene, hexafluoropropylene, CF ₂ = CFOR ^f1 ( Here, R ^f1 is a perfluoroalkyl group having 1 to 10 carbon atoms and optionally containing an etheric oxygen atom.), CF ₂ ═CFOR ^f2 SO ₂ X ¹ (R ^f2 is an etheric group having 1 to 10 carbon atoms) A perfluoroalkylene group which may contain an oxygen atom, X ¹ is a halogen atom or a hydroxyl group), CF ₂ ═CFOR ^f ₂ CO ₂ X ² (where R ^f2 is the same as above, X ² is a hydrogen atom or carbon; A C 1-3 alkyl group), CF ₂ ═CF (CF ₂ ) _p OCF═CF ₂ (wherein p is 1 or 2), CH ₂ = CX ³ (CF ₂ ) _q X ⁴ (wherein X ³ and X ⁴ are each independently a hydrogen atom or a fluorine atom, q is an integer of 2 to 10), perfluoro (2-methylene- 4-methyl-1,3-dioxolane) and the like.

Other fluorine-containing monomers are preferably at least one selected from the group consisting of VdF, HFP, CF ₂ = CFOR ^f1 and CH ₂ = CX ³ (CF ₂ ) _q X ⁴ , CF ₂ = CFOR ^f1 or CH ₂ = CX ³ (CF ₂ ) _q X ⁴ is more preferred.
CF ₂ = CFO ^f1 includes CF ₂ = CFOCF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₂ CF ₃ , CF ₂ = CFO (CF ₂ ) ₈ F, etc. Can be mentioned. Preferably, CF ₂ = CFOCF ₂ CF ₂ CF ₃ .
As CH ₂ = CX ³ (CF ₂ ) _q X ⁴ , CH ₂ = CH (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₃ F, CH ₂ = CH (CF ₂ ) ₄ F, CH ₂ ═CF (CF ₂ ) ₃ H, CH ₂ ═CF (CF ₂ ) ₄ H, and the like. Preferably, CH ₂ ═CH (CF ₂ ) ₄ F or CH ₂ ═CH (CF ₂ ) ₂ F.

  Moreover, as a non-fluorine monomer (however, except the said cyclic hydrocarbon monomer), C2-C4 olefins, such as ethylene, propylene, 2-methylpropylene, are preferable, and it consists of ethylene, propylene, and 2-methylpropylene. At least one selected from the group is more preferable.

  The adhesive fluororesin in the present invention includes tetrafluoroethylene-perfluoro (alkyl vinyl ether) -AM copolymer, ethylene-tetrafluoroethylene-AM copolymer, tetrafluoroethylene-hexafluoropropylene-AM copolymer. Examples thereof include a polymer, an ethylene-chlorotrifluoroethylene-AM copolymer, and a chlorotrifluoroethylene-AM copolymer. Preferred are an ethylene-tetrafluoroethylene-AM copolymer and a tetrafluoroethylene-perfluoro (alkyl vinyl ether) -AM copolymer.

The volume flow rate of the adhesive fluorocarbon resin in the present invention (hereinafter, also referred to as Q value.) Is preferably 0.1~1000mm ³ / sec, 1 to 100 mm ³ / sec is more preferable. Volume flow rate is a measure of molecular weight, with large values representing low molecular weight. If the capacity flow rate is within this range, the moldability is good. The capacity flow rate in the present invention is an adhesion when extruded into an orifice having a diameter of 2.1 mm and a length of 8 mm under a load of 7 kg at a temperature 50 ° C. higher than the melting point of the adhesive fluororesin using a flow tester manufactured by Shimadzu Corporation. This is the extrusion speed of the functional fluororesin.
Moreover, 150-320 degreeC is preferable and, as for melting | fusing point of the adhesive fluororesin in this invention, 200-310 degreeC is more preferable. An adhesive fluororesin having a melting point within this range is particularly excellent in melt moldability. Note that the melting point of the adhesive fluororesin can be appropriately adjusted depending on the content ratio of each repeating unit contained in the adhesive fluororesin.

Further, the breaking strength of the adhesive fluororesin in the present invention is preferably 5 to 100 MPa, more preferably 10 to 90 MPa, and further preferably 20 to 100 MPa.
In addition, the breaking elongation of the adhesive fluororesin in the present invention is preferably 50 to 1000%, more preferably 100 to 800%, and still more preferably 300 to 600.

  When the adhesive fluororesin in the present invention is produced by a method of copolymerizing a fluorine-containing monomer such as tetrafluoroethylene and a monomer having a carbonyl group and having a polymerizable unsaturated bond, a radical polymerization initiator is used. The polymerization method used is used. Examples of the polymerization method include bulk polymerization, solution polymerization using an organic solvent such as fluorinated hydrocarbon, chlorohydrocarbon, fluorinated chlorohydrocarbon, alcohol, hydrocarbon, an aqueous medium, and an appropriate organic solvent as necessary. Examples include suspension polymerization to be used, emulsion polymerization using an aqueous medium and an emulsifier, and solution polymerization is particularly preferable.

The radical polymerization initiator is a radical polymerization initiator having a half-life of 10 hours, preferably 0 ° C to 100 ° C, more preferably 20 to 90 ° C. Specific examples include azo compounds such as azobisisobutyronitrile, non-fluorinated diacyl peroxides such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, lauroyl peroxide, and diisopropyl peroxydicarbonate. Peroxyesters such as peroxydicarbonate, tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate, tert-butyl peroxyacetate, (Z (CF ₂ ) _p COO) ₂ (where Z is Inorganic peroxidation such as fluorine-containing diacyl peroxide, potassium persulfate, sodium persulfate, ammonium persulfate such as a compound represented by a hydrogen atom, fluorine atom or chlorine atom, and p is an integer of 1 to 10. Thing etc. are mentioned.

  In the present invention, it is also preferable to use a chain transfer agent in order to control the volume flow rate of the adhesive fluororesin. Chain transfer agents include alcohols such as methanol and ethanol, chlorofluorohydrocarbons such as 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane, Hydrocarbons such as pentane, hexane, and cyclohexane are listed. When a chain transfer agent having a functional group such as an ester group, carbonate group, hydroxyl group, carboxyl group, or carbonyl fluoride group is used, the fluorine-containing copolymer has excellent adhesion to a synthetic resin other than a fluorine-containing polymer such as polyamide. It is preferable because a polymer end group is introduced. Examples of the chain transfer agent include acetic acid, acetic anhydride, methyl acetate, ethylene glycol, propylene glycol and the like.

The polymerization conditions are not particularly limited, and the polymerization temperature is preferably 0 to 100 ° C, more preferably 20 to 90 ° C. The polymerization pressure is preferably from 0.1 to 10 MPa, more preferably from 0.5 to 3 MPa. The polymerization time is preferably 1 to 30 hours.
The concentration of AM during polymerization is preferably 0.01 to 5 mol%, more preferably 0.1 to 3 mol%, and most preferably 0.1 to 1 mol% with respect to all monomers. When the concentration of AM is too high, the polymerization rate tends to decrease. Within the above range, the polymerization rate during production does not decrease, and the fluorinated copolymer is excellent in adhesiveness. During the polymerization, AM is consumed in the polymerization. Therefore, it is preferable to supply the consumed AM amount continuously or intermittently into the polymerization tank and maintain the AM concentration within this range.

  Adhesive fluororesin, within the range that does not impair the properties of the target packing, weathering agent, lubricant, filler, plasticizer, hindered phenol-based, phosphorus-based, sulfur-based antioxidants, ultraviolet absorbers, Various additives such as antistatic agents, antiblocking agents, anticlouding agents, dyes and pigments, resin compositions, and the like can be added.

The packing for insulating seals of the lithium ion secondary battery of the present invention can be used as packing for insulating seals of various lithium ion secondary batteries.
The structure of a suitable lithium ion secondary battery to which the packing for insulating seals of the lithium ion secondary battery of the present invention can be applied includes a positive electrode plate in which a material containing a positive electrode active material is applied to the current collector, and a negative electrode on the current collector An electrode plate laminate in which a negative electrode plate coated with a material containing an active material and a separator interposed between the positive electrode plate and the negative electrode plate are spirally wound, and the upper and lower portions of the columnar body have larger plate-like portions. A positive electrode terminal and a negative electrode terminal, a positive electrode terminal, a ring-shaped positive electrode and negative electrode insulating seal packing having a central hole portion closely fitted to a columnar part of the negative electrode terminal, a positive electrode and a negative electrode lead plate, a positive electrode and a negative electrode buffer ring, The thing which comprises is mentioned.

  The electrode plate laminate 1 may be folded or overlapped in addition to a spiral wound with a separator interposed between a positive electrode plate and a negative electrode plate. In addition, the shape of the entire battery is generally round (cylindrical) in cross section, but other than that, the cross section may be square (prism) or other shapes.

As the positive electrode active material used in the lithium ion secondary battery, all known materials capable of electrochemically occluding and releasing lithium ions can be used, and among them, a material containing lithium is preferable. For example, the general formula Li _x M _y N _z O ₂ (M is at least one metal selected from the group consisting of transition metal elements Co, Ni, Fe, Mn, Cr, V, Ti, Cu, Zr, N Is at least one metal selected from the group consisting of Al, In, Sn, B, Mg, Si, Ge, Ga, Y, La, Ce, Pr, Nd, Sm, and 0 <x ≦ 1.1 , 0.5 ≦ y ≦ 1.0, z ≦ 0.1) is preferable. More preferably, lithium cobaltate, lithium nickelate, spinel type lithium manganate, LiMn ₂
O is _4.
A conductive additive is added to the positive electrode active material. As the conductive aid, non-graphitic carbonaceous materials such as activated carbon, coke, carbon black, and graphite are added.

As the negative electrode active material used in the lithium ion secondary battery, all known materials that can electrochemically occlude and release lithium ions can be used. In particular, graphite powder, mesophase carbon fiber, mesophase spherule, metal oxide, metal, alloy, nitride and the like are preferable.
Any conventionally known electrolyte can be used as the electrolyte. For example, LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiCl, LiBr, CF ₃ SO ₃ Li Etc.

The non-aqueous solvent is not particularly limited, and any conventionally known solvent can be used. For example, ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3- Examples include dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile and the like. A solvent can be used 1 type or in mixture of 2 or more types.
The electrolyte is dissolved in a non-aqueous solvent and used in the form of a solution. In addition, the solution may be impregnated with a polymer material such as polyvinylidene fluoride to be used in a sol-like or gel-like state.
As the separator, a polyolefin microporous film, a polyolefin fiber woven or non-woven fabric, a resin such as cellulose, an inorganic woven fabric, a non-woven fabric, a paper body, a porous body, a solid electrolyte film, and a mixture thereof are used. It is done.

As the positive electrode current collector, metal foil such as Al, Ti, and stainless steel, expanded metal, punch metal, foam metal, carbon cloth, carbon paper, and the like are used.
As the negative electrode current collector, a metal foil such as Cu, Ni, stainless steel, an expanded metal, a punch metal, a foam metal, or the like is used.
The material for sealing the battery body may be any resin that is excellent in electrolyte solution resistance, chemical resistance, heat resistance, mechanical strength, heat sealability, and molding processability, such as olefins such as polyethylene and polypropylene. Resins, polymer alloys thereof, Al foil laminate films, electron beam cross-linked polyethylene, γ-ray cross-linked polyethylene, and polyphenylene ether resins are used. In particular, from the viewpoint of strength and heat resistance, electron beam cross-linked polyethylene, γ-ray cross-linked polyethylene, polyester film laminated with Al foil, and polypropylene film are preferable. The thickness is preferably 0.05 to 1.00 mm.

  The reinforcing metal cover only needs to reinforce the sealed battery body and give it sufficient strength. For example, a sheet of general-purpose steel plate Al alloy, Mg alloy, etc. is used, and its thickness (portable In the case of a small battery of 0.05 to 0.30 mm. Practically, a Ni-plated steel plate or a galvanized steel plate having a thickness of about 0.1 mm is preferable, and the surface is preferably decorated by printing or the like. The reinforcing metal cover does not necessarily need to be bent and formed from the sheet, and a metal pipe may be used instead.

  The positive electrode terminal and the negative electrode terminal only need to have excellent conductivity and corrosion resistance. As the positive electrode terminal, for example, Al, Al alloy, Ti, Ti alloy, stainless steel or the like is used, and the negative electrode terminal 3b For example, Fe, Cu, Ni, alloys thereof, stainless steel, Ni-plated steel, Ni-plated Cu, or the like is used. As the insulating seal packing for the positive electrode and the negative electrode, resins and rubbers excellent in elasticity, sealing properties, chemical resistance, heat resistance, mechanical strength, molding processability and the like are preferable. In the present invention, in particular, it is essential that the adhesiveness with a metal is excellent so as not to cause electrolyte leakage.

As the positive electrode and the negative electrode lead plate, those excellent in conductivity, corrosion resistance and the like are preferable. As the positive electrode lead plate, for example, Al, Al alloy, Ti, Ti alloy, stainless steel or the like is used. As the negative electrode lead plate, for example, Fe, Cu, Ni, their alloys, stainless steel or the like is used.
The method of insulating sealing a lithium ion secondary battery according to the present invention is such that the surface of a metal member to be sealed by the packing is preheated at 200 to 600 ° C. in an oxygen-containing atmosphere, and then a primer is applied to the surface. Then, a primer layer is formed, and then the insulating seal packing is melt bonded to the primer layer.

The adhesive fluororesin is melt-bonded to the surface of the metal member. Examples of the metal of the metal member include stainless steel, copper, brass, iron, aluminum, nickel, magnesium alloy, and titanium. Among these, at least one selected from the group consisting of aluminum, copper, nickel, and stainless steel is preferable.
The adhesive bonding of the adhesive fluororesin to the metal member is performed by heating and melting the adhesive fluororesin and applying pressure.

As a method of bonding the metal member and the insulating seal packing, an adhesive fluororesin such as compression molding, transfer molding, injection molding, injection molding capable of independently controlling the temperature of the hot part is melted, and the metal member is A molding method for injecting into the combined mold can be adopted.
In the insulating sealing method for a lithium ion secondary battery of the present invention, the surface of the metal member to be sealed by the packing is preheated at 200 to 600 ° C. in an oxygen-containing atmosphere, and then a primer is applied to the surface. It is preferable to form a primer layer and then melt and bond the packing onto the primer layer.

As for the heat processing temperature of the surface of a metal member, 300-500 degreeC is more preferable, and 350-450 degreeC is the most preferable. In both cases where the temperature is lower than this range and when the temperature is high, the adhesion between the adhesive fluororesin packing having a carbonyl group and the metal member is not sufficient. The heat treatment time is preferably 10 minutes to 5 hours, more preferably 30 minutes to 2 hours. The atmosphere containing oxygen is preferably air because special equipment is not required. Moreover, it is preferable to pre-process the surface of a metal member by methods, such as a sandblast process, a phosphate process, hydrochloric acid process, a sulfuric acid process, an organic solvent process, before heat processing.

The metal member is usually cooled to near room temperature after the heat treatment.
A primer is applied to the surface of the metal member cooled to near room temperature.
The primer in the method for insulating sealing a lithium ion secondary battery of the present invention preferably comprises a silane coupling agent having an amino group and a partial hydrolyzate thereof, or a mixture thereof.
As the silane coupling agent having an amino group, the general formula R ⁴ R ⁵ N—R ¹ —Si (R ² ) _n (OR ³ ) _{3 -n} (where R ¹ is an alkylene group having 2 to 8 carbon atoms). Or a phenylene group, R ² is an alkyl group or phenyl group having 1 to 6 carbon atoms, R ³ is a hydrogen atom, an alkyl group or phenyl group having 1 to 6 carbon atoms, R ⁴ and R ⁵ are each independently a hydrogen atom Or an organic group having 1 to 6 carbon atoms, n represents 0 or 1. The same shall apply hereinafter.), And R ⁷ R ⁸ N—R ⁶ —NR ⁴ —R ¹ —Si (R ² ) _n (OR ³ A silane cup represented by _3-n (wherein R ⁶ is an alkylene group having 2 to ⁶ carbon atoms, and R ⁷ and R ⁸ are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms). A ring agent is preferred.

Examples of ^{R 1,} preferably an alkylene group having 2 to 8 carbon _{atoms, (CH 2) 2, (} CH 2) 3, (CH 2) 4 are more preferable, _{(CH 2) 3} is most preferred. R ² is preferably a methyl group or a phenyl group, and more preferably a methyl group. R ³ is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group. n is more preferably 0. R ⁴ or R ⁵ is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ⁶ is preferably an alkylene group, more preferably (CH ₂ ) ₂ , (CH ₂ ) ₃ , (CH ₂ ) ₄ , and most preferably (CH ₂ ) ₂ . R ⁷ or R ⁸ is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom.

Specific examples of the silane coupling agent having an amino group include the following.
3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-methyl-3-aminopropyltrimethoxysilane, N-methyl-3 -Aminopropyltriethoxysilane, N-methyl-3-aminopropylmethyldiethoxysilane, N, N'-dimethyl-3-aminopropylmethyldimethoxysilane, N, N'-dimethyl-3-aminopropylmethyldiethoxysilane 2-aminoethyl-3-aminopropyltrimethoxysilane, 2-aminoethyl-3-aminopropyltriethoxysilane, 2-aminoethyl-3-aminopropylmethyldimethoxysilane, 2-aminoethyl-3-aminopropylmethyl Diethoxysilane (N-methyl-2-aminoethyl) -3-aminopropyltrimethoxysilane, (N-methyl-2-aminoethyl) -3-aminopropyltriethoxysilane, (N-methyl-2-aminoethyl) -3 -Aminopropylmethyldiethoxysilane, (N, N'-dimethyl-2-aminoethyl) -3-aminopropyltrimethoxysilane, (N, N'-dimethyl-2-aminoethyl) -3-aminopropyltriethoxy Silane, (N, N′-dimethyl-2-aminoethyl) -3-aminopropylmethyldiethoxysilane, 3-aminoethyltrimethoxysilane, 2-aminoethyltriethoxysilane,
4-aminobutyltrimethoxysilane, 6-aminohexyltriethoxysilane, 8-aminooctyltriethoxysilane, 4-aminophenyltrimethoxysilane.
Among them, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane, 2 -Aminoethyl-3-aminopropyltriethoxysilane, 2-aminoethyl-3-aminopropylmethyldimethoxysilane and 2-aminoethyl-3-aminopropylmethyldiethoxysilane are preferred. A silane coupling agent having an amino group and a partial hydrolyzate thereof may be used alone or in combination of two or more.

A partial hydrolyzate of an amino group-containing silane coupling agent can be easily produced by reacting an amino group-containing silane coupling agent with a predetermined amount of water in the presence of a catalyst such as an acid. The molecular weight of the partial hydrolyzate produced can be controlled by the amount of water used.
The silane coupling agent having an amino group, a partial hydrolyzate thereof, or a mixture thereof is preferably used by diluting in a solvent such as water or alcohol. The concentration is preferably 0.1 to 10% by mass, more preferably 0.5 to 7% by mass, and most preferably 1 to 5% by mass. If the concentration is lower than this range, the adhesiveness with the adhesive fluororesin packing having a carbonyl group is insufficient, and if it is higher than this range, the dispersibility of the primer is insufficient and the coating workability is low.

For the primer, a silane coupling agent not having an amino group, tetraalkoxysilanes, Ti or Al alkoxides may be mixed and used, and co-hydrolyzed with an amino group-containing silane coupling agent, It may be used as a cohydrolyzate.
The primer layer is formed by applying a solution of an amino group-containing silane coupling agent, a partial hydrolyzate thereof, or a mixture thereof onto the surface of a metal member by dipping, spin coating, spraying, brushing, roll coating, or the like. , Formed by drying. The drying temperature is preferably room temperature to 150 ° C, more preferably room temperature to 130 ° C. The drying time is preferably 0 to 60 minutes, more preferably 10 to 40 minutes.
The thickness of the primer layer is preferably 5 to 500 μm, more preferably 10 to 300 μm, and still more preferably 20 to 200 μm.

FIG. 2 shows a specific example of the lithium ion secondary battery according to the present invention that is insulated and sealed.
FIG. 2 shows a cross-sectional shape of the insulating seal portion of the lithium ion secondary battery.
In the gap between the metal fastening washer 3, the metal narrow pressure receiving plate 6, the metal fastening member 7 (current collector terminal, electrode terminal) and the metal lid member 9 in FIG. The insulating seal packing made of fluororesin is heated and melted, and is bonded and introduced by applying pressure. The metal member was pre-heated at 200 to 600 ° C. in an oxygen-containing atmosphere, and the surface of the metal member to be sealed with the packing was preliminarily treated, and then a primer was applied to the surface to form a primer layer. Is.

Hereinafter, the present invention will be described with reference to Examples (Examples 1, 2, 3, 6, and 7) and Comparative Examples (Examples 4, 5, 8, and 9), but the present invention is not limited thereto. The acid anhydride content, copolymer composition, melting point, breaking strength, breaking elongation, and adhesive strength of the adhesive fluororesin were measured by the following methods.
[Content of repeating unit based on 5-norbornene-2,3-dicarboxylic anhydride (hereinafter referred to as NAH) (unit: mol%)]
An infrared absorption spectrum was measured using a 100 μm adhesive fluororesin film. Since the absorption peak of NAH in the infrared absorption spectrum appears at 1778 cm ⁻¹ , the absorbance of the peak was measured. The content of repeating units based on NAH was calculated using a molar extinction coefficient of NAH of 1340 l · mol ⁻¹ · cm ⁻¹ .

[Content of repeating unit based on itaconic anhydride (unit: mol%)]
The content of the repeating unit based on itaconic anhydride (hereinafter referred to as IAN) in the fluorine-containing polymer is determined by infrared absorption spectrum analysis, and the absorption peak of C═O stretching vibration in the repeating unit is 1870 cm ^{−. Since} it appears in ¹ , the absorbance of the absorption peak was measured, and the content M (mol%) of the repeating unit based on IAN was determined using the relational expression of M = aL. Here, L is the absorbance at 1870 cm ⁻¹ , and a is a coefficient. As a, a = 0.87 determined by using IAN as a model compound was used.
[Content of repeating unit based on CF ₂ = CFO (CF ₂ ) ₃ F (unit: mol%)]
In accordance with the method described in Asahi Glass Research Report 40 (1), 75 (1990), it was calculated by melt NMR analysis.

[Melting point (° C)]
Using a DSC apparatus manufactured by Seiko Electronics Co., Ltd., a melting peak was recorded when the temperature was raised at a rate of 10 ° C./min, and the temperature (° C.) corresponding to the maximum value was defined as the melting point (Tm).
[Break strength (MPa), elongation at break (%)]
Using a sample of a 1 mm thick dumbbell piece using a press sheet, the strength at break when tensile at a dumbbell shape of 5, a distance between chucks of 25.4 mm, and a speed of 50 mm / min in accordance with ASTM D638-00 is broken. The value divided by the area and the elongation at that time were taken as the breaking strength and breaking elongation, respectively.

[Adhesive strength (unit: N / cm)]
An adhesive fluororesin film having a thickness of 50 μm was laminated with an aluminum foil, a copper foil, and a stainless steel plate, and predetermined temperature, pressure, and time were set by a press molding machine and melt-bonded. The obtained laminated film was cut into strips having a length of 10 cm and a width of 1 cm to prepare test pieces. The peel strength of the test piece was measured using a tensile tester to obtain the adhesive strength.

[Example 1]
A polymerization tank equipped with a stirrer having an internal volume of 1.2 L was degassed, and 1131 g of 1,3-dichloro-1,1,2,2,3-pentafluoropropane (AK225cb manufactured by Asahi Glass Co., Ltd., hereinafter referred to as AK225cb). , CF ₂ = CFO (CF ₂ ) ₃ F (hereinafter referred to as PPVE) was charged. Next, the temperature in the polymerization tank was raised to 50 ° C., and 73 g of tetrafluoroethylene (hereinafter referred to as TFE) was charged to increase the pressure to 0.43 MPa / G. The polymerization initiator solution as charged 1 cm ³ of 0.1 wt% AK225cb solution of (perfluoro butyryl) peroxide, polymerization was started and charged with 1 cm ³ of the polymerization initiator solution every 10 minutes thereafter. Further, TFE was continuously charged so that the pressure during the polymerization was maintained at 0.43 MPa / G. In addition, a 0.3 mass% AK225cb solution of NAH in an amount corresponding to 0.1 mol% with respect to the number of moles of TFE charged during the polymerization was continuously charged. After 5 hours from the start of polymerization, when 50 g of TFE was charged, the temperature in the polymerization tank was lowered to room temperature and purged to normal pressure.

The slurry of the obtained fluorinated copolymer 1 was filtered through a glass filter to separate the solvent, and then dried at 150 ° C. for 15 hours to obtain 45 g of fluorinated copolymer 1.
From the results of melt NMR analysis and infrared absorption spectrum analysis, the copolymer composition of the fluorinated copolymer 1 is as follows: repeating unit based on TFE / repeating unit based on PPVE / repeating unit based on NAH = 93.4 / 6.5. /0.1 (mol%). The melting point was 270 ° C., the Q value was 0.45 mm ³ / sec, the breaking strength was 28 MPa, and the elongation was 350%.
The adhesive strength with the copper foil was 11.5 N / cm, and the adhesive strength with the aluminum foil was 10.5 N / cm, both of which were found to be excellent in adhesiveness.

  As a metal member, a stainless steel plate made of SUS304 having a size of 50 mm × 100 mm and a thickness of 2 mm was used. The metal member was immersed in ethanol for 30 minutes and then heat-treated at 400 ° C. for 1 hour in air. 2 g of 2-aminoethyl-3-aminopropyltrimethoxysilane, 3 g of distilled water, and 94 g of methanol were placed in a beaker and stirred at 23 ° C. for 1 hour to obtain a primer solution. The primer solution was applied to the surface of the metal member at room temperature so that the dry film thickness was 1 μm, dried at room temperature, and then heated and dried at 120 ° C. for 30 minutes to form a primer layer. The primer solution was uniform and excellent in coating workability. A film (thickness 50 μm) of the fluorinated copolymer 1 was melt bonded at 340 ° C. and a pressure of 2 Mpa on the surface of the metal member having the primer layer. The adhesion strength between the primer-treated stainless steel 304 base material was 9.8 N / cm, and the adhesion strength between the stainless steel 304 not subjected to the primer treatment and the base material was 6.5 N / cm. It was found that the adhesiveness was excellent.

[Example 2]
The same polymerization tank as used in Example 1 was degassed, 500 g of AK225cb, 600 g of hexafluoropropylene (hereinafter referred to as HFP) and 50 g of TFE were charged, and the temperature in the polymerization tank was raised to 50 ° C. The pressure was 0.98 MPa / G. Was charged 1 cm ³ of 0.25 mass% AK225cb solution of di (perfluoro-butyryl) peroxide as a polymerization initiator solution, the polymerization was started and charged with 1 cm ³ of the polymerization initiator solution every 10 minutes thereafter. Further, TFE was continuously charged so that the pressure during the polymerization was maintained at 0.98 MPa / G. Further, a 0.3 mass% AK225cb solution of NAH in an amount corresponding to 0.1 mol% of TFE continuously charged was continuously charged. At the time when 50 g of TFE was charged 4 hours and 20 minutes after the start of polymerization, the inside of the polymerization tank was cooled to room temperature and unreacted monomers were purged.

The resulting slurry of fluorinated copolymer 2 was filtered through a glass filter to separate the solvent, and then dried at 150 ° C. for 15 hours to obtain 55 g of fluorinated copolymer 2.
From the results of melt NMR analysis and infrared absorption spectrum analysis, the copolymer composition of the fluorinated copolymer 2 is as follows: repeating unit based on TFE / repeating unit based on HFP / repeating unit based on NAH = 92.6 / 7.3 /0.1 (mol%). The melting point was 270 ° C., the Q value was 2.1 mm ³ / sec, the breaking strength was 31 MPa, and the elongation was 370%.
The adhesive strength with the aluminum foil was 8.4 N / cm, and the adhesive strength with the copper foil was 6.8 N / cm, both of which were found to be excellent in adhesiveness.

[Example 3]
The same polymerization tank as used in Example 1 was degassed, 500 g of AK225cb, 600 g of HFP, 25 g of PPVE, and 50 g of TFE were charged, and the inside of the polymerization tank was heated to 50 ° C. The pressure was 0.96 MPa / G. Was charged 1 cm ³ of 0.25 mass% AK225cb solution of di (perfluoro-butyryl) peroxide as a polymerization initiator solution, the polymerization was started and charged with 1 cm ³ of the polymerization initiator solution every 10 minutes thereafter. TFE was continuously charged so that the pressure was maintained at 0.96 MPa / G during the polymerization. Further, a 0.3 mass% AK225cb solution of NAH in an amount corresponding to 0.1 mol% of TFE continuously charged was continuously charged. At the time when 50 g of TFE was charged 4 hours and 40 minutes after the start of polymerization, the inside of the polymerization tank was cooled to room temperature, and unreacted monomers were purged.

The resulting slurry of fluorinated copolymer 3 was filtered through a glass filter to separate the solvent, and then dried at 150 ° C. for 15 hours to obtain 55 g of fluorinated copolymer 3.
From the results of melt NMR analysis and infrared absorption spectrum analysis, the copolymer composition of the fluorinated copolymer 3 is: repeating unit based on TFE / repeating unit based on hexafluoropropene / repeating unit based on PPVE / repeating unit based on NAH. = 91.4 / 7.0 / 1.5 / 0.1 (mol%). The melting point was 257 ° C., the Q value was 3.2 mm ³ / sec, the breaking strength was 30 MPa, and the elongation was 400%.
The adhesive strength with the aluminum foil was 11.2 N / cm, and the adhesive strength with the copper foil was 10.4 N / cm, both of which were found to be excellent in adhesiveness.

[Example 4 (comparative example)]
A fluorinated copolymer 4 was obtained in the same manner as in Example 1 except that NAH was not charged. From the result of melt NMR analysis, the copolymer composition of the fluorinated copolymer 4 was a repeating unit based on TFE / a repeating unit based on PPVE = 95.5 / 4.5 (mol%). The melting point was 285 ° C., the Q value was 0.25 mm ³ / sec, the breaking strength was 30 MPa, and the elongation was 430%. The film of the fluorinated copolymer 4 did not adhere at all to the copper foil, the aluminum foil, and the stainless steel 304 base material and the stainless steel 304 base material treated with the primer in Example 1.

[Example 5 (comparative example)]
40 g of fluorinated copolymer 5 was obtained in the same manner as in Example 2 except that NAH was not charged. From the results of melt NMR analysis and infrared absorption spectrum analysis, the copolymer composition of the fluorinated copolymer 5 was a repeating unit based on TFE / a repeating unit based on PPVE = 93.7 / 6.3 (mol%). It was. The melting point was 275 ° C., the Q value was 1.58 mm ³ / sec, the breaking strength was 28 MPa, and the elongation was 450%. The film of the fluorinated copolymer 5 did not adhere at all to the copper foil, the aluminum foil, and the stainless steel 304 base material and the stainless steel 304 base material treated with the primer in Example 1.

[Example 6]
Degas the same polymerization tank used in Example 1, 889 g of 1-hydrotridecafluorohexane, 328.8 g of AK225cb, 7.3 g of CH ₂ ═CH (CF ₂ ) ₂ F, 165 g of TFE, 4.4 g of ethylene was charged. Next, the temperature in the polymerization tank was raised to 66 ° C. The pressure in the polymerization tank was 1.448 MPa / G. As a polymerization initiator solution, 9.6 cm ³ of a 2% by mass 225 cb solution of tert-butyl peroxypivalate was charged to initiate polymerization. A 60/40 (molar ratio) mixed gas of TFE and ethylene was continuously charged so that the pressure was maintained at 1.448 MPa / G during the polymerization. Further, CH ₂ ═CH (CF ₂ ) ₂ F in an amount corresponding to 3.3 mol% and IAH corresponding to 0.5 mol% with respect to the total number of moles of a mixed gas of TFE and ethylene charged during the polymerization. A 0.8 mass% AK225cb solution was continuously charged. 3.4 hours after the start of polymerization, when 100 g of a mixed gas of TFE and ethylene was charged, the temperature in the polymerization tank was lowered to room temperature and purged to normal pressure.

The slurry of the obtained fluorinated copolymer 6 was filtered through a glass filter to separate the solvent, and then dried at 150 ° C. for 15 hours to obtain 105 g of fluorinated copolymer 6.
From the results of melt NMR analysis and fluorine content analysis, the copolymer composition of the fluorinated copolymer 6 is a repeating unit based on TFE / a repeating unit based on ethylene / a repeating unit based on CH ₂ ═CH (CF ₂ ) ₂ F. The repeating unit based on / IAH was 58.0 / 38.6 / 3.1 / 0.3 (mol%). The melting point was 237 ° C., the Q value at 297 ° C. was 45 mm ³ / sec, the breaking strength was 42 MPa, and the elongation was 370.

  The adhesive strength with the copper foil was 9.4 N / cm, and the adhesive strength with the aluminum foil was 11.2 N / cm. It was found that both had excellent adhesiveness. Further, as a metal member, a stainless steel plate made of SUS304 having a size of 50 mm × 100 mm and a thickness of 2 mm was immersed in ethanol for 30 minutes, and then heat-treated at 400 ° C. for 1 hour in air. 2 g of 2-aminoethyl-3-aminopropyltrimethoxysilane, 3 g of distilled water, and 94 g of methanol were placed in a beaker and stirred at 23 ° C. for 1 hour to obtain a primer solution. The primer solution was applied to the surface of the metal member at room temperature so that the dry film thickness was 1 μm, dried at room temperature, and then heated and dried at 120 ° C. for 30 minutes to form a primer layer. The primer solution was uniform and excellent in coating workability. The fluorine-containing copolymer 1 film was melt-bonded to the surface of the metal member having the primer layer at 280 ° C. and a pressure of 3 Mpa. The adhesive strength between the primer-treated stainless steel 304 base material was 11.1 N / cm, and the adhesive strength between the stainless steel 304 base material not subjected to the primer treatment was 5.8 N / cm. It was found that the adhesiveness was excellent.

[Example 7]
Degas the same polymerization vessel used in Example 1, 602 g of 1-hydrotridecafluorohexane, 201 g of AK225cb, 377 g of HFP, 3.2 g of CH ₂ ═CH (CF ₂ ) ₄ F, TFE. 105 g and 3.3 g of ethylene were charged. Next, the temperature in the polymerization tank was raised to 66 ° C. The pressure in the polymerization tank was 1.475 MPa / G. As a polymerization initiator solution, 5.8 cm ³ of a 5 mass% 225 cb solution of tert-butyl peroxypivalate was charged to initiate polymerization. A mixed gas of 54/46 (molar ratio) of TFE and ethylene was continuously charged so that the pressure was maintained at 1.475 MPa / G during the polymerization. Further, CH ₂ ═CH (CF ₂ ) ₄ F in an amount corresponding to 1.0 mol% and NAH corresponding to 0.2 mol% with respect to the total number of moles of the TFE and ethylene mixed gas charged during the polymerization. A 0.9 mass% AK225cb solution was continuously charged. 5.2 hours after the start of polymerization, when 70 g of a mixed gas of TFE and ethylene was charged, the temperature inside the polymerization tank was lowered to room temperature and purged to normal pressure.

The slurry of the resulting fluorinated copolymer 7 was filtered through a glass filter to separate the solvent, and then dried at 120 ° C. for 15 hours to obtain 79 g of fluorinated copolymer 7.
From the results of melt NMR analysis and fluorine content analysis, the copolymer composition of the fluorinated copolymer 7 is as follows: repeating unit based on TFE / repeating unit based on ethylene / repeating unit based on HFP / CH ₂ ═CH (CF ₂ ). _The repeating unit based on ₄ F / the repeating unit based on NAH = 46.7 / 43.3 / 8.9 / 1.0 / 0.1 (mol%). The melting point was 175 ° C., the Q value at 220 ° C. was 21 mm ³ / sec, the breaking strength was 39 MPa, and the elongation was 450%.

  The adhesive strength with the copper foil was 8.5 N / cm, and the adhesive strength with the aluminum foil was 10.2 N / cm, all of which were found to be excellent in adhesiveness. Moreover, it immersed in ethanol for 30 minutes using the stainless steel plate made from SUS304 of 50 mm x 100 mm and thickness 2mm as a metal member, Then, it heat-processed at 400 degreeC for 1 hour in the air. Next, 3 g of 2-aminoethyl-3-aminopropyltrimethoxysilane, 3 g of distilled water, and 94 g of methanol were placed in a beaker and stirred at 23 ° C. for 1 hour to obtain a primer solution. The primer solution was applied to the surface of the iron plate at room temperature so that the dry film thickness was 1 μm, dried at room temperature, and then heated and dried at 120 ° C. for 30 minutes to form a primer layer. The primer solution was uniform and excellent in coating workability. The fluorine-containing copolymer 1 film was adhered to the surface of the primer thus prepared, and the fluorine-containing copolymer 7 film was melt-bonded to the surface of the metal member having the primer layer at 240 ° C. and a pressure of 2.5 Mpa. It was. Melt bonded. The adhesive strength between the primer-treated stainless steel 304 base material was 9.6 N / cm, and the adhesive strength between the stainless steel 304 base material not subjected to the primer treatment was 4.8 N / cm. It was found that the adhesiveness was excellent.

[Example 8 (comparative example)]
A fluorinated copolymer 8 was obtained in the same manner as in Example 6 except that IAH was not charged. From the results of the melt NMR analysis and the fluorine content analysis, the copolymer composition of the fluorinated copolymer 8 is a repeating unit based on TFE / a repeating unit based on ethylene / a repeating unit based on CH ₂ ═CH (CF ₂ ) ₂ F. = 58.0 / 38.9 / 3. 1 (mol%). The melting point was 240 ° C., the Q value at 297 ° C. was 40 mm ³ / sec, the breaking strength was 43 MPa, and the elongation was 380%. The film of the fluorinated copolymer 8 did not adhere at all to the copper foil, the aluminum foil, and the stainless steel 304 base material and the stainless steel 304 base material subjected to the primer treatment in Example 1.

[Example 9 (comparative example)]
A fluorinated copolymer 9 was obtained in the same manner as in Example 7 except that IAH was not charged. From the results of melt NMR analysis and fluorine content analysis, the copolymer composition of the fluorinated copolymer 9 is as follows: repeating unit based on TFE / repeating unit based on ethylene / repeating unit based on HFP / CH ₂ ═CH (CF ₂ ). _The repeating unit based on ₄ F = 46.7 / 43.3 / 9.0 / 1.0 (mol%). The melting point was 175 ° C., the Q value at 220 ° C. was 18 mm ³ / sec, the breaking strength was 40 MPa, and the elongation was 476%.
The film of the fluorinated copolymer 9 did not adhere at all to the copper foil, the aluminum foil, and the primer-treated stainless steel 304 base material and the stainless steel 304 base material in Example 1.

FIG. 1 is a schematic cross-sectional view of a lithium ion secondary battery. FIG. 2 is a cross-sectional view of an insulating seal portion of the lithium ion secondary battery.

Explanation of symbols

1 Screw part (current collection terminal, electrode terminal)
2 Fastening nut 3 Fastening washer 4 Insulating packing 5 Insulating packing 6 Narrow pressure receiving plate 7 Fastening member (current collection terminal, electrode terminal)
8 Narrow pressure plate 9 Lid material 10 Primer layer 11 Electrode plate laminate 12 Electrode can 13 Sealing body (positive electrode terminal)
14 Insulating packing 15 Positive electrode lead 16 Constricted part

Claims (11)

  An insulating seal packing for a lithium ion secondary battery, comprising an adhesive fluororesin having a carbonyl group.   2. The lithium ion secondary battery according to claim 1, wherein the carbonyl group contained in the adhesive fluororesin is at least one selected from the group consisting of an acid anhydride group, a carboxyl group, an acid halide group, and a carbonate group. Insulation seal packing. The adhesive fluorine resin having a carbonyl group is a fluorine-containing copolymer obtained by copolymerizing a fluorine-containing monomer and a monomer having a carbonyl group and having a polymerizable unsaturated bond. The packing for insulation seals of the lithium ion secondary battery as described. The adhesive fluororesin having the carbonyl group has (a) a repeating unit based on tetrafluoroethylene and / or chlorotrifluoroethylene, (b) an acid anhydride group, and a polymerizable unsaturated group in the ring. A repeating unit based on a cyclic hydrocarbon monomer and (c) a repeating unit based on another fluorine-containing monomer (excluding tetrafluoroethylene and chlorotrifluoroethylene), the repeating unit (a), and the repeating unit The repeating unit (a) is 50 to 99.89 mol% and the repeating unit (b) is 0.01 to 5 mol% based on the total molar amount of the unit (b) and the repeating unit (c). , and the said a repeating unit (c) is from 0.1 to 49.99 mol%, volume flow rate 0.1~1000mm ³ / sec Packing insulating sealing of the lithium ion secondary battery according to claim 2 or 3 which is located fluorocopolymer.   The cyclic hydrocarbon monomer having an acid anhydride group and having a polymerizable unsaturated group in the ring is selected from the group consisting of itaconic anhydride, citraconic anhydride and 5-norbornene-2,3-dicarboxylic anhydride. The packing for insulation sealing of the lithium ion secondary battery according to claim 4, wherein the packing is at least one kind. The other fluorine-containing monomer is vinylidene fluoride, hexafluoropropylene, CF ₂ = CFOR ^f1 (where R ^f1 is a perfluoroalkyl group having 1 to 10 carbon atoms and optionally containing an etheric oxygen atom). And CH ₂ = CX ³ (CF ₂ ) _q X ⁴ (wherein X ³ and X ⁴ are each independently a hydrogen atom or a fluorine atom, q is an integer of 2 to 10). The packing for insulation sealing of a lithium ion secondary battery according to any one of claims 3 to 5, wherein the packing is at least one kind. The fluorine-containing copolymer further contains (d) a repeating unit based on a non-fluorine monomer (excluding the cyclic hydrocarbon monomer), and the repeating unit (a), the repeating unit (b), and the The insulating seal for a lithium ion secondary battery according to any one of claims 3 to 6, wherein the content of the repeating unit (d) is 5 to 90 mol% with respect to the total number of moles of the repeating unit (c). Packing.   The packing for insulating seals of a lithium ion secondary battery according to claim 7, wherein the non-fluorine monomer is at least one selected from the group consisting of ethylene, propylene, and 2-methylpropylene. An insulating sealing method for a lithium ion secondary battery using the insulating seal packing for the lithium ion secondary battery according to claim 1, wherein the sealing is performed by the packing at 200 to 600 ° C. in an oxygen-containing atmosphere. A surface of a metal member to be heated in advance, and then a primer is applied to the surface to form a primer layer, and then the packing is melt bonded to the primer layer. Insulation sealing method.   The method for insulating sealing a lithium ion secondary battery according to claim 9, wherein the metal in the metal member is at least one selected from the group consisting of aluminum, copper, nickel, and stainless steel.   The method of insulating sealing a lithium ion secondary battery according to claim 9 or 10, wherein the shape of the metal member is a fastening member, a lid, or a flange member.

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