JP5772412B2 - Lithium ion battery exterior material, lithium ion battery - Google Patents

Description

  The present invention relates to a lithium ion battery exterior material and a lithium ion battery using the lithium ion battery exterior material.

Conventionally, nickel-metal hydride and lead-acid batteries have been used as secondary batteries, but miniaturization of secondary batteries has become indispensable due to downsizing of portable devices and restrictions on installation space. In order to meet the demand for miniaturization, lithium ion batteries with high energy density have attracted attention and are being adopted. A lithium ion battery has a positive electrode, a negative electrode, and an electrolyte layer inside an exterior material, and the electrolyte layer includes an aprotic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and an electrolyte. Or a polymer gel impregnated with the electrolytic solution. As the electrolyte, lithium salts such as LiPF ₆ and LiBF ₄ are used. Conventionally, metal cans have been used as exterior materials, but laminate-type exterior materials using multilayer films that are lightweight, have high heat dissipation properties, and can be handled at low cost have come to be used.

In a lithium ion battery, the lithium salt that is an electrolyte generates hydrofluoric acid by a hydrolysis reaction with moisture, which may cause corrosion of the metal and a decrease in laminate strength between layers of the multilayer film. Therefore, an aluminum foil layer is generally contained in the multilayer film constituting the exterior material of the lithium ion battery for the purpose of preventing moisture intrusion, and the moisture intrusion from the surface of the multilayer film is blocked. An exterior material composed of such a multilayer film is called an aluminum laminate type.
The multilayer film as described above generally has a structure in which a sealant layer is laminated on one surface of an aluminum foil layer via an adhesive layer, and a base material layer is laminated on the other surface via an adhesive layer (base material layer). / Adhesive layer / aluminum foil layer / adhesive layer / sealant layer), and optionally another intermediate layer (for example, a corrosion prevention treatment layer) is provided between these layers. Adhesive layers can be broadly classified into two types: a dry laminate structure composed of an adhesive resin layer for dry laminate and a heat laminate structure composed of a thermoplastic material. Since the adhesive used for the dry laminate structure has a highly hydrolyzable bond such as an ester group or a urethane group, a hydrolysis reaction with hydrofluoric acid is likely to occur. Therefore, for applications that require high reliability, a thermal laminate configuration is used.

Lithium-ion batteries using laminate-type exterior materials are made by sealing the outer edge of the multilayer film so that the sealant layer is on the inside so that one side opens, and the battery contents ( (A positive electrode, a negative electrode, an electrolyte layer, etc.) are housed and sealed, and a multilayer film is formed with a recess by cold forming, and the battery contents are housed in the recess and sealed. The latter form is often taken because it can accommodate more battery contents and increase the energy density. In this form, normally, one of a pair of multilayer films is cold-molded to form a molded member, and the other is used as a sealing member for sealing the opening of the concave portion of the molded member without performing cold-molding. Although there is a method of performing cold forming on both of the pair of multilayer films, it is not general because the alignment of the forming portion, the sealing method after storing the electrolytic solution, and the like are difficult.
Currently, there is no distinction between the multilayer film that performs cold forming and the multilayer film that does not perform cold forming, and the same multilayer film is used.

The main performance required for the exterior material for a lithium ion battery of the type that performs the cold forming as described above is divided into an inner layer side, an outer layer side, and the whole. The performance required on the inner layer side includes acid resistance (resistance to hydrofluoric acid generated from the electrolyte), low water vapor permeability and heat seal performance, and the performance required on the outer layer side is rubbing resistance. The performance required for the whole includes thin film formation, heat dissipation performance, and molding performance. Specifically, the molding performance is required to be able to mold the recess without causing defects such as cracks during cold molding.
Among these, the thin film formation and the heat dissipation performance have a strong positive correlation, and if the film can be made thin, high heat dissipation can be obtained. However, thinning has a strong negative correlation with forming performance and imparting acid resistance to the outer layer side while maintaining the forming performance, and it is difficult to satisfy these performances simultaneously.
Examples of materials that contribute to molding performance include the material and film thickness of the base material layer, the adhesive material between the base material layer and a metal foil layer such as an aluminum foil layer, and the material and film thickness of the metal foil layer. In particular, the material and the film thickness of the base material layer strongly contribute to the molding performance, and when the base material layer is thinned, the molding performance is lowered. For this reason, it is difficult to make the outer packaging material for a lithium ion battery thin without impairing the molding performance.

Examples of a method for imparting acid resistance to the outer layer side while maintaining molding performance include a method for imparting an acid resistant layer to a base layer having high molding performance. Specifically, a base layer having high molding performance is provided. And a method of laminating an acid-resistant film substrate, and a method of applying an acid-resistant layer coating to a substrate layer having high molding performance.
The multilayer film configuration described in Patent Document 1 is a laminate of a biaxially stretched polyester film layer, a biaxially stretched nylon film layer, and a metal foil layer sequentially from the outside by a dry laminate method, and has resistance to an electrolyte and acid. A biaxially stretched nylon film is laminated on the outer side of the multilayer film with the biaxially stretched polyester film being the outermost layer, and a high impact strength can be maintained.
In the multilayer film configuration described in Patent Document 2, the outermost layer of the laminate configuration includes polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, maleic anhydride-modified polypropylene, polyester resin, epoxy resin, phenol resin, fluororesin, It is said that acid resistance and moldability can be achieved by providing at least one coating layer selected from cellulose ester, urethane resin and acrylic resin.
However, in these methods, the base material layer becomes thick, and problems such as thickening of the lithium ion battery and a decrease in heat dissipation arise.

JP 2002-56824 A Japanese Patent No. 3567229

As described above, at present, it is difficult to simultaneously maintain the molding performance of the exterior material of the lithium ion battery, reduce the film thickness, improve the heat dissipation performance, and impart acid resistance.
The present invention has been made in view of the above circumstances, and is capable of simultaneously achieving molding performance maintenance, thin film formation, improvement of heat dissipation performance and imparting acid resistance, and lithium ion using the exterior material. An object is to provide a battery.

As a result of intensive studies, the present inventors have classified the multilayer film constituting the lithium battery exterior material into a molded member and a sealing member in the lithium battery exterior material, and set the layer configuration of each multilayer film. It was found that this is very effective in solving the above problems.
This invention is made | formed based on the said knowledge, and has the following aspects.
[1] A lithium ion battery exterior material comprising at least a molding member having a recess formed by cold forming and a sealing member for sealing the opening of the recess,
The molded member comprises a multilayer film for molded members having a laminate structure in which a base material layer A1, an adhesive layer B1, an aluminum foil layer C1, a corrosion prevention treatment layer D1, an adhesive layer E1, and a heat seal layer F1 are sequentially laminated.
The sealing member comprises a multilayer film for a sealing member having a laminate structure in which a base material layer A2, an adhesive layer B2, a metal foil layer C2, a corrosion prevention treatment layer D2, an adhesive layer E2, and a heat seal layer F2 are sequentially laminated. And at least the base material layer A1 has a single layer or multi-layer structure including a stretched polyamide film, and the base material layer A2 has a single layer or a multi-layer structure not including a stretched polyamide film. Lithium ion battery exterior material.
[2] The lithium ion battery exterior material according to [1], wherein the metal foil layer C2 has a thickness of 30 μm or less.
[3] The lithium ion battery exterior material according to [1] or [2], wherein the thickness of the base material layer A2 is 25 μm or less.
[4] A lithium ion battery comprising the lithium ion battery exterior material according to [1].
In Patent Documents 1 and 2, there is no distinction between the molded member and the sealing member in the multilayer film, and the problems of thickening the lithium ion battery and reducing heat dissipation cannot be solved.

  ADVANTAGE OF THE INVENTION According to this invention, the lithium ion battery exterior material which can achieve simultaneously maintenance of shaping | molding performance, thin film formation, improvement of heat dissipation performance, and provision of acid resistance, and a lithium ion battery using this exterior material can be provided.

It is a schematic sectional drawing which shows the structure of the lithium ion battery exterior material 10 of one Embodiment of this invention. It is a schematic sectional drawing which shows an example of a structure of the multilayer film for molded members. It is a schematic sectional drawing which shows an example of a structure of the multilayer film for sealing members.

≪Lithium ion battery exterior material≫
The lithium ion battery exterior material of the present invention is a lithium ion battery exterior material composed of a molded member having at least a recess formed by cold forming and a sealing member for sealing the opening of the recess,
The molded member comprises a multilayer film for molded members having a laminate structure in which a base material layer A1, an adhesive layer B1, an aluminum foil layer C1, a corrosion prevention treatment layer D1, an adhesive layer E1, and a heat seal layer F1 are sequentially laminated.
The sealing member comprises a multilayer film for a sealing member having a laminate structure in which a base material layer A2, an adhesive layer B2, a metal foil layer C2, a corrosion prevention treatment layer D2, an adhesive layer E2, and a heat seal layer F2 are sequentially laminated. And at least the base material layer A1 has a single layer or multi-layer structure including a stretched polyamide film, and the base material layer A2 has a single layer or a multi-layer structure not including a stretched polyamide film. To do.

In this invention, the multilayer film which comprises a lithium battery exterior material is divided into the object for shaping | molding members, and the object for sealing members, and makes the structure of each multilayer film different.
For example, as a multilayer film for a molded member, a lithium battery exterior material that has been conventionally used is used in order to provide molding performance and the like. Uses different packaging materials for lithium batteries.
Since the multilayer film for a sealing member can be designed without considering the molding performance, the degree of freedom in design is increased, and the component members can be optimized and the film can be made thinner.
Here, “the configuration is different” means that the layers (A1 and A2, B1 and B2, C1 and C2, D1 and D2) located at corresponding positions between the multilayer film for molded member and the multilayer film for sealing member. , E1 and E2, and F1 and F2) are different materials. In the present invention, at least the base material layer A1 and the base material layer A2 have different structures.

Hereinafter, a lithium ion battery exterior material and a lithium ion battery using the same according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a configuration of a lithium ion battery exterior material 10 according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the configuration of the multilayer film for molded member constituting the molded member 1 included in the lithium ion battery exterior material 10, and FIG. 3 is the multilayer film for sealing member constituting the sealing member 2. It is a schematic sectional drawing which shows this structure.
The lithium ion battery exterior material 1 includes a molded member 1 formed by forming a concave portion 1a by cold forming on a multilayer film for molded member, and a sealing member 2 formed of the multilayer film for sealing member.
Cold forming is a forming method performed at room temperature, and examples thereof include press forming such as deep drawing forming and stretch forming.
The multilayer film for molded members has a laminate structure in which a base material layer A1, an adhesive layer B1, an aluminum foil layer C1, a corrosion prevention treatment layer D1, an adhesive layer E1, and a heat seal layer F1 are sequentially laminated. Thereby, the performance required for the lithium battery exterior film for molded members can be expressed.
The multilayer film for a sealing member has a laminate configuration in which a base material layer A2, an adhesive layer B2, a metal foil layer C2, a corrosion prevention treatment layer D2, an adhesive layer E2, and a heat seal layer F2 are sequentially laminated. Thereby, the performance required for the film for sealing members can be expressed.

[Multilayer film for molded parts]
<Base material layer A1>
As the base material layer A1, a resin layer having a single layer structure or a multilayer structure including a stretched polyamide film is used. As described above, the moldability of the lithium ion battery exterior material has a strong correlation with the material of the base material layer. By using such a resin layer as the base material layer A1, the moldability when forming a molded member by cold forming is improved.
Examples of such a resin layer include a stretched or unstretched polyamide film, a stretched or unstretched polyester film, a two-layer film of a stretched polyamide film and a stretched polyester film, and the like.
In terms of excellent moldability and heat resistance, a stretched polyamide film is preferable, and in the case of imparting acid resistance, a two-layer film of a stretched polyamide film and a stretched polyester film is suitable.
The thickness of the base material layer A1 is preferably 6 μm or more and more preferably 10 μm or more in terms of improving moldability, heat resistance, pinhole resistance, and insulation. Moreover, 60 micrometers or less are preferable and 45 micrometers or less are more preferable at the point of thin film formation and high heat dissipation.

Various additives such as an acid resistance imparting agent, a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, and a light stabilizer are provided on the outermost layer surface (the surface opposite to the adhesive layer B1 side) of the base material layer A1. A tackifier or the like may be applied.
Examples of the acid resistance imparting agent include polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, maleic anhydride-modified polypropylene, polyester resin, epoxy resin, phenol resin, fluororesin, cellulose ester, urethane resin, acrylic resin, and the like. .
Examples of the slip agent include fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, ethylene bisoleic acid amide, and ethylene biserucic acid amide.
As the antiblocking agent, various fillers such as silica are suitable.
These additives may be used alone or in combination of two or more.

<Adhesive layer B1>
The adhesive layer B1 is a layer that improves the adhesion between the base material layer A1 and the aluminum foil layer C1.
Examples of the material constituting the adhesive layer B1 include a polyurethane resin obtained by allowing a bifunctional or higher functional isocyanate compound to act on a main agent composed of a polyol such as polyester polyol, polyether polyol, acrylic polyol, and carbonate polyol.
As the polyester polyol, one obtained by reacting at least one polybasic acid with at least one diol can be used. Examples of polybasic acids include aliphatic dibasic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, spellic acid, azelaic acid, sebacic acid, and brassic acid, and aromatics such as isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. And dibasic acids such as group dibasic acids. Diols include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol and other aliphatic diols, cyclohexanediol, hydrogenated xylylene Examples thereof include alicyclic diols such as lenglicol and aromatic diols such as xylylene diol.
Further, as the polyester polyol, a hydroxyl group at both ends of the polyester polyol, a polyester urethane polyol in which chain is extended using an isocyanate compound alone or an adduct body, a burette body or an isocyanurate body made of at least one isocyanate compound, etc. Can be mentioned. Examples of the isocyanate compound include 2,4- or 2,6-tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2,2,4- or 2, Examples include 4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and isopropylidene dicyclohexyl-4,4′-diisocyanate.
As the polyether polyol, it is possible to use an ether-based polyol such as polyethylene glycol or polypropylene glycol, or a polyether urethane polyol in which the above-described isocyanate compound is allowed to act as a chain extender.
Examples of the acrylic polyol include a copolymer containing poly (meth) acrylic acid as a main component. Examples of the copolymer include hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, and methyl groups, ethyl groups, n-propyl groups, i-propyl groups as alkyl groups. Group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, alkyl (meth) acrylate monomer, and (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide (As the alkyl group, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group) Cyclohexyl group, etc.), N-alkoxy (meth) acrylamide, N, N-dialkoxy (meta) Acrylamide, (as alkoxy groups, methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), amide group-containing monomers such as N-methylol (meth) acrylamide, N-phenyl (meth) acrylamide, glycidyl (meth) acrylate, Glycidyl group-containing monomers such as allyl glycidyl ether,
Examples include those obtained by copolymerizing silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane and (meth) acryloxypropyltriethoxylane, and isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate.
As the carbonate polyol, one obtained by reacting a carbonate compound and a diol can be used. As the carbonate compound, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, or the like can be used. Examples of the diol include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol, and other aliphatic diols, cyclohexanediol, hydrogenated Arocyclic diols such as xylylene glycol, aromatic diols such as xylylene glycol, and the like can be used.
Further, it is possible to use a polycarbonate urethane polyol in which the terminal hydroxyl group of the carbonate polyol is chain-extended with the above-described isocyanate compound.
These various polyols may be used alone or in the form of a blend of two or more depending on the required function and performance.
As a curing agent for these main agents, it is possible to use the same type of isocyanate compound used as a chain extender, and although it is repeated, 2,4- or 2,6-tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate 4,4′-dicyclohexylmethane diisocyanate, isopropylidene dicyclohexyl-4,4′-diisocyanate, etc. At least one adduct consisting of an isocyanate compound selected from the isocyanate compound, biuret body, isocyanurate products thereof.

A carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent, and the like can be further blended with the main agent to promote adhesion.
Examples of the carbodiimide compound include N, N′-di-o-toluylcarbodiimide, N, N′-diphenylcarbodiimide, N, N′-di-2,6-dimethylphenylcarbodiimide, N, N′-bis (2,6 -Diisopropylphenyl) carbodiimide, N, N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N, N'-di-2,2-di-t-butylphenylcarbodiimide, N-triyl-N ' -Phenylcarbodiimide, N, N'-di-p-nitrophenylcarbodiimide, N, N'-di-p-aminophenylcarbodiimide, N, N'-di-p-hydroxyphenylcarbodiimide, N, N'-di- Examples thereof include cyclohexylcarbodiimide and N, N′-di-p-toluylcarbodiimide.
As the oxazoline compound, monooxazoline compounds such as 2-oxazoline, 2-methyl-2-oxazoline, 2-phenyl-2-oxazoline, 2,5-dimethyl-2-oxazoline, 2,4-diphenyl-2-oxazoline, 2,2 ′-(1,3-phenylene) -bis (2-oxazoline), 2,2 ′-(1,2-ethylene) -bis (2-oxazoline), 2,2 ′-(1,4- And dioxazoline compounds such as butylene) -bis (2-oxazoline) and 2,2 ′-(1,4-phenylene) -bis (2-oxazoline).
Epoxy compounds include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, polyalkylene glycol, sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, trimethylolpropane, etc. Polyglycidyl ether of aliphatic polyols, polyglycidyl ether of alicyclic polyols such as cyclohexanedimethanol, aliphatic and aromatic such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, sebacic acid Diglycidyl ester or polyglycidyl ester of polycarboxylic acid, resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p-hydroxyphenyl) propa , Diglycidyl ether or polyglycidyl ether of polyhydric phenols such as tris- (p-hydroxyphenyl) methane, 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane, N, N′-diglycidylaniline, N-glycidyl derivatives of amines such as N, N, N-diglycidyl toluidine, N, N, N ′, N′-tetraglycidyl-bis- (p-aminophenyl) methane, triglycidyl derivatives of aminofail, tri Examples thereof include glycidyl tris (2-hydroxyethyl) isocyanurate, triglycidyl isocyanurate, orthocresol type epoxy, and phenol novolac type epoxy.
Examples of phosphorus compounds include tris (2,4-di-t-butylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) 4,4′-biphenylenephosphonite, bis (2,4 -Di-t-butylphenyl) pentaerythritol-di-phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, 2,2-methylenebis (4,6 -Di-t-butylphenyl) octyl phosphite, 4,4'-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl) -4-ditridecyl phosphite-5-t-butyl-phenyl) butane, tris (mixed mono and di-nonylphenyl) phosphite, tris (nonyl) Eniru) phosphite, 4,4'-isopropylidene-bis (phenyl - dialkyl phosphite), and the like.
As silane coupling agents, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Propyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β Various silane coupling agents such as (aminoethyl) -γ-aminopropyltrimethoxysilane can be used.
In addition, various additives and stabilizers may be blended depending on the performance required for the adhesive.

<Aluminum foil layer C1>
As the aluminum foil constituting the aluminum foil layer C1, generally used soft aluminum foil can be used, but the iron content is 0 for the purpose of imparting further pinhole resistance and extensibility during molding. It is preferable to use an aluminum foil in the range of 0.1 to 9.0% by mass, preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, pinhole resistance and ductility are sufficiently imparted, and when it is 9.0% by mass or less, flexibility is good.
The aluminum foil is preferably subjected to a degreasing treatment. Degreasing treatment is largely classified into wet type and dry type.
Examples of the wet type degreasing treatment include acid degreasing and alkali degreasing.
Examples of acid degreasing include a method of using an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid alone or a mixture of two or more thereof. In some cases, various metal salts serving as a supply source of Fe ions, Ce ions, and the like are blended as needed to improve the etching effect of aluminum. Examples of alkali degreasing include strong etching types such as sodium hydroxide, and there are cases where weak alkalis and surfactants are blended. These degreasing and etching are performed by dipping or spraying.
Examples of the dry type degreasing treatment include a method of performing in an aluminum annealing step. Moreover, a frame process, a corona process, etc. are mentioned. Furthermore, a degreasing treatment in which contaminants are oxidatively decomposed and removed by active oxygen generated by irradiation with ultraviolet rays having a specific wavelength is also included.
The degreasing treatment may be performed on one side or both sides of the aluminum foil.
The thickness of the aluminum foil layer C1 is preferably 9 to 200 μm and more preferably 15 to 100 μm in view of barrier properties, pinhole resistance and workability.

<Corrosion prevention treatment layer D1>
The corrosion prevention treatment layer D1 is basically a layer provided to prevent corrosion of the aluminum foil layer C1 due to the electrolytic solution or hydrofluoric acid.
Examples of the corrosion prevention treatment include degreasing treatment, hydrothermal alteration treatment, anodizing treatment, chemical conversion treatment, or a combination of two or more of these treatments.
Degreasing treatment includes acid degreasing and alkali degreasing. Examples of the acid degreasing include a method using the above-described inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid alone or a mixture thereof. Also, as acid degreasing, by using an acid degreasing agent in which a fluorine-containing compound such as monosodium ammonium difluoride is dissolved with the above inorganic acid, not only the degreasing effect of the metal foil but also a metal fluoride that is passive is formed. This is effective in terms of resistance to hydrofluoric acid. Examples of the alkaline degreasing include a method using sodium hydroxide and the like.
Examples of the hydrothermal modification treatment include boehmite treatment obtained by immersing a metal foil in boiling water to which triethanolamine is added.
Examples of the anodizing treatment include alumite treatment.
Examples of the chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments composed of these mixed phases.
These hydrothermal modification treatment, anodizing treatment, and chemical conversion treatment are preferably performed in advance with the above-described degreasing treatment. These chemical conversion treatments are not limited to the wet type, but can be applied to a coating type in which these treatment agents are mixed with a resin component.

Among the above-mentioned treatments, especially hot water modification treatment and anodizing treatment dissolve the metal foil (aluminum foil) surface with a treatment agent, and further form a compound having excellent corrosion resistance, thereby preventing corrosion from the metal foil. In order to form a co-continuous structure up to the treatment layer, there are cases where it is included in the definition of chemical conversion treatment, but it is not included in the definition of chemical conversion treatment as described below, pure coating type corrosion prevention It is also possible to form a corrosion prevention treatment layer only by treatment.
This coating type corrosion prevention treatment has a corrosion prevention effect (inhibitor effect) of metal foil, and is also a suitable material from the environmental viewpoint, and is a rare earth element oxide such as cerium oxide having an average particle size of 100 nm or less. By using this method, it is possible to impart a metal foil corrosion prevention effect even by a general coating method.
The sol of rare earth element oxides such as cerium oxide can use various solvents such as aqueous, alcohol-based, hydrocarbon-based, ketone-based, ester-based, and ether-based solvents. It is preferable to use the sol.
In order to stabilize the dispersion of such an oxide sol, an inorganic acid such as nitric acid, hydrochloric acid or phosphoric acid, or an organic acid such as acetic acid, malic acid, ascorbic acid or lactic acid is usually used as a dispersion stabilizer. . Among these dispersion stabilizers, phosphoric acid is not only “sol dispersion stabilization”, but also for the lithium battery exterior material for this application. "Improvement of adhesion", "Providing resistance to electrolytes" by capturing metal ions eluted under the influence of hydrofluoric acid ("Providing resistance to electrolytes"), "Aggregation of oxide layer due to easy dehydration and condensation of phosphoric acid even at low temperatures""Strengthening" is expected. Examples of such phosphoric acid or salts thereof include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and alkali metal salts and ammonium salts thereof. In particular, condensed phosphoric acid such as trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, and ultrametaphosphoric acid, or alkali metal salts and ammonium salts thereof are also preferable for function expression as a lithium battery packaging material. In particular, an agent that is excellent in reactivity at low temperatures is preferable in consideration of dry film-forming properties (drying ability, heat amount) when a layer made of rare earth oxide is formed by various coating methods using the rare earth oxide sol. For this reason, Na ion salts having excellent dehydration condensation properties at low temperatures are preferably used. The salt forming the phosphate is not particularly limited, but more preferably a water-soluble salt.
As a compounding ratio of cerium oxide and phosphoric acid (or a salt thereof), phosphoric acid (or a salt thereof) is preferably 1 part by mass or more with respect to 100 parts by mass of cerium oxide. If the amount is less than 1 part by mass, the sol is not stabilized and it may be difficult to satisfy the function as a lithium battery exterior material. The blending amount of phosphoric acid (or a salt thereof) with respect to 100 parts by mass of cerium oxide is more preferably 5 parts by mass or more. The blending upper limit of phosphoric acid (or a salt thereof) may be within a range not accompanied by a decrease in the function of the cerium oxide sol, and is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and more preferably 20 parts by mass with respect to 100 parts by mass of cerium oxide. Part or less is more preferable.

However, since the layer formed from the rare earth oxide sol described above is an aggregate of inorganic particles, the cohesive force of the layer itself is low even after the drying curing step. Therefore, in order to supplement the cohesive strength of this layer, it is preferable to make a composite with an anionic polymer.
Examples of the anionic polymer include polymers having a carboxy group. Specifically, poly (meth) acrylic acid (or a salt thereof) or a monomer mixture mainly composed of (meth) acrylic acid is copolymerized. And a copolymer obtained. Monomers used together with (meth) acrylic acid in the monomer mixture include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, and t-butyl as alkyl groups. Group, 2-ethylhexyl group, cyclohexyl group alkyl (meth) acrylate monomer, and further (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide (as alkyl group, Methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxy (meth) acrylamide, N , N-dialkoxy (meth) acrylamide (the alkoxy groups include methoxy, ethoxy, Xy group, isobutoxy group, etc.), amide group-containing monomers such as N-methylol (meth) acrylamide, N-phenyl (meth) acrylamide, and hydroxyl groups such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate -Containing monomers, glycidyl group-containing monomers such as glycidyl (meth) acrylate, allyl glycidyl ether, silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane, (meth) acryloxypropyltriethoxylane, (meth) acryloxypropyl Examples include isocyanate group-containing monomers such as isocyanate.
The anionic polymer is a material used for improving the stability of the oxide layer obtained using the rare earth element oxide sol as described above. The effect is to protect the hard and brittle oxide layer with an acrylic resin component, and also to trap phosphate-derived ion contamination (particularly sodium ions) contained in the rare earth oxide sol (cation catcher). ) Effect. Not limited to the lithium ion battery used in the present invention, for example, in a protective layer (corrosion prevention treatment layer) provided to prevent corrosion of the metal foil by a corrosive compound, ion contamination, particularly alkali metal ions such as sodium or alkali If earth metal ions are included, there is a problem that the protective layer is affected by the ion contamination. That is, anionic polymers such as polyacrylic acid are effective in that ion contamination such as sodium ions contained in the rare earth element oxide sol described later is fixed and the resistance of the film is improved.

As described above, the anionic polymer can be used in combination with the rare earth element oxide sol as a corrosion prevention treatment layer in a lithium battery exterior material, thereby imparting corrosion prevention performance equivalent to that of chromate treatment. Such an effect is further improved by crosslinking an anionic polymer that is essentially water-soluble as described above.
The anionic polymer can be crosslinked using a crosslinking agent, and examples of such a crosslinking agent include compounds having an isocyanate group, a glycidyl group, a carboxy group, and an oxazoline group.
Examples of the compound having an isocyanate group include tolylene diisocyanate, xylylene diisocyanate or hydrogenated product thereof, hexamethylene diisocyanate, 4-4 ′ diphenylmethane diisocyanate or hydrogenated product thereof, diisocyanates such as isophorone diisocyanate, or these isocyanates. Polyisocyanates such as adducts obtained by reacting polyhydric alcohols with polyhydric alcohols such as trimethylolpropane, burette obtained by reacting with water, or isocyanurates which are trimers, or polyisocyanates thereof. Examples thereof include blocked polyisocyanates obtained by blocking isocyanates with alcohols, lactams, oximes and the like.
Examples of the compound having a glycidyl group include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, Epoxy compounds made by reacting glycols such as neopentyl glycol and epichlorohydrin, epoxy compounds made by reacting polychlorinated alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol and epichlorohydrin, terephthalic acid phthalate, sulphate Examples thereof include an epoxy compound obtained by reacting a dicarboxylic acid such as acid or adipic acid with epichlorohydrin.
Examples of the compound having a carboxy group include various aliphatic or aromatic dicarboxylic acids, and it is also possible to use poly (meth) acrylic acid or alkali (earth) metal salts of poly (meth) acrylic acid. is there.
The compound having an oxazoline group is an acrylic monomer such as (meth) acrylic acid or (meth) acrylic when a low molecular compound having two or more oxazoline units or a polymerizable monomer such as isopropenyl oxazoline is used. Those obtained by copolymerization with an acid alkyl ester, hydroxyalkyl (meth) acrylate, or the like can be used.
Furthermore, it is also possible to make a crosslinking point into a siloxane bond using a silane coupling agent. As silane coupling agents, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyl Examples include trichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, and γ-isocyanatopropyltriethoxysilane, particularly anionic In consideration of the reactivity with the polymer, epoxy silane, amino silane, and isocyanate silane are preferably used.
1-50 mass parts is suitable for the compounding quantity of these crosslinking agents with respect to 100 mass parts of anionic polymers. If the amount is less than 1 part by mass, the crosslinking structure is insufficient, and if it is more than 50 parts by mass, the coating pot life may be reduced. Preferably, it is 10-20 mass parts.
The method of crosslinking the anionic polymer is not limited to the above-mentioned crosslinking agent, and a crosslinked structure such as ionic crosslinking using titanium or a zirconium compound may be formed.

  When forming a corrosion prevention treatment layer by the above-described coating type corrosion prevention treatment, it is necessary to form an inclined structure between the metal foil layer and the chemical conversion treatment layer, unlike the chemical conversion treatment represented by chromate treatment. No. In order to form a gradient structure with this metal foil, the chemical conversion treatment represented by chromate is applied to the metal foil using a chemical conversion treatment agent containing hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid or a salt thereof. As described above, the chemical conversion treatment layer is formed on the metal foil by reacting with a chromium-free compound. However, since these treatment agents use an acid, they are accompanied by corrosion of the work environment and coating equipment. The coating process described above does not require a tilted structure to be formed on the metal foil, and in that respect, the definition is different from the chemical conversion process. As a result, since the properties of the coating agent are not restricted by acidity, alkalinity or neutrality, it can be said that it is a treatment method that is also friendly to the work environment. Considering this, it can be said that the content is also interesting from the point of view of the corrosion prevention technical field where an alternative is desired.

The corrosion prevention treatment layer D1 is formed by laminating a layer formed from the above-described rare earth oxide sol or a layer obtained by combining a rare earth oxide sol and an anionic polymer with a combination of a cationic polymer and a crosslinking agent. It may be a multilayer structure.
Examples of the cationic polymer include ethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is grafted to an acrylic main skeleton, polyallylamine or a derivative thereof, amino Phenol etc. are mentioned.
As a crosslinking agent, what has a functional group which can react with amine / imine, such as a carboxyl group and a glycidyl group, is preferable.
In addition, a polymer having a carboxylic acid that forms an ionic polymer complex with polyethyleneimine can also be used as a crosslinking agent. Examples thereof include polycarboxylic acids (salts) such as polyacrylic acid or ionic salts thereof, and comonomers. And a polysaccharide having a carboxyl group such as carboxymethylcellulose or an ionic salt thereof. As the polyallylamine, homopolymers or copolymers of allylamine, allylamine amide sulfate, diallylamine, dimethylallylamine and the like can be used. Furthermore, these amines can be free amines or stabilized with acetic acid or hydrochloric acid. It is possible to use. Further, maleic acid, sulfur dioxide or the like can be used as a copolymer component. Furthermore, it is possible to use a type in which a primary amine is partially methoxylated to impart thermal crosslinkability. Aminophenol can also be used. Particularly preferred is allylamine or a derivative thereof.
In addition, although this cationic polymer is described as one component constituting the corrosion prevention treatment layer, the reason for this is that the electrolyte solution resistance and the hydrofluoric acid resistance required for the lithium battery exterior material are imparted. As a result of conducting sincerity studies using various compounds as much as possible, it was found that the cationic polymer itself is a compound that can impart electrolyte solution resistance and hydrofluoric acid resistance. This factor is presumed to be because the fluorine ions are trapped with a cationic group (anion catcher), thereby suppressing damage to the metal foil. For this reason, when the rare earth oxide sol is used as the above-described corrosion prevention treatment layer, a cationic polymer may be used instead of using the above-mentioned anionic polymer as the protective layer.

From the above, as an example of the combination of the above-mentioned coating type corrosion prevention treatment,
(1) Rare earth oxide sol only
(2) Anionic polymer only
(3) Cationic polymer only
(4) Rare earth oxide sol + anionic polymer (laminated composite),
(5) Rare earth oxide sol + cationic polymer (laminated composite),
(6) (rare earth oxide sol + anionic polymer: laminated composite) / cationic polymer (multilayered),
(7) (rare earth oxide sol + cationic polymer: laminated composite) / anionic polymer (multilayered),
Etc. However, it is not necessarily limited to these. For example, as an example of selecting a corrosion prevention treatment layer, the cationic polymer is a very preferable material in that it has good adhesiveness with the modified polyolefin resin mentioned in the description of the adhesive layer E1 described later. Can be designed such that a cationic polymer is provided on the surface in contact with the adhesive layer E1 (for example, configurations (5) and (6)).

  Not limited to the contents described above, for example, by using an agent in which phosphoric acid and a chromium compound are blended in a resin binder (such as aminophenol), such as a coating chromate that is a known technique, it has both a corrosion prevention function and adhesion. Layer can be formed. In addition, in order to improve adhesion to the above-described chemical conversion treatment layer (a layer formed by degreasing treatment, hydrothermal modification treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments), the above-described cation has been used. It is also possible to perform a complex treatment using an ionic polymer or an anionic polymer, or to laminate a cationic polymer or an anionic polymer as a multilayer structure for a combination of these treatments. In addition, although it is necessary to consider the stability of the coating liquid, it is also possible to use a coating agent obtained by previously making one solution of the rare earth oxide sol and the cationic polymer or anionic polymer described above. .

Corrosion prevention treatment layer D1 is preferably the mass per unit area provided so as to be in the range of 0.005~0.200g / ^{m 2,} the range of 0.010~0.100g / ^{m 2} It is more preferable to provide as described above. If it is thinner than 0.005 g / m ^2, the corrosion prevention function of the metal foil layer may be affected. If it is thicker than 0.200 g / m ² , the performance of the corrosion prevention function is saturated, or in the case of using a rare earth oxide sol, if the coating is thick, curing due to heat during drying becomes insufficient. , There is a risk that the cohesive force is reduced.
In addition, although it described with the mass per unit area in the said content, if specific gravity is known, it is also possible to convert thickness from there.

<Adhesive layer E1>
The adhesive layer E1 is a layer used when the corrosion prevention treatment layer D1 and the sealant layer F1 are bonded together.
The material constituting the adhesive layer E1 is roughly classified into two types, a heat-adhesive resin and an adhesive.
As the heat-adhesive resin, a modified polyolefin resin obtained by graft-modifying an unsaturated carboxylic acid derivative component derived from an unsaturated carboxylic acid or an acid anhydride or an ester thereof in the presence of an organic peroxide with respect to the polyolefin resin. Is mentioned.
Examples of the polyolefin resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-α olefin copolymer, homo, block, random polypropylene, and propylene-α olefin copolymer.
Of unsaturated carboxylic acids or acid anhydrides or esters thereof used for graft modification of polyolefin resins, unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydro Examples thereof include phthalic acid and bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid. Examples of unsaturated carboxylic acid anhydrides include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic anhydride Etc. Unsaturated carboxylic acid esters include methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconic acid, dimethyl tetrahydrophthalate And dimethyl bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylate.
As the modified polyolefin resin described above, the unsaturated carboxylic acid or acid anhydride or ester thereof is added in an amount of 0.2 to 100 parts by mass to 100 parts by mass of the base polyolefin resin, and in the presence of a radical initiator. It can be manufactured by heating. The reaction temperature condition is usually 50 to 250 ° C, preferably 60 to 200 ° C. Although the reaction time depends on the production method, in the case of a melt graft reaction by a twin screw extruder, it is within the residence time of the extruder, for example, 2 to 30 minutes, preferably about 5 to 10 minutes. Further, the denaturation reaction can be carried out under both normal pressure and pressurized conditions.
Examples of the radical initiator used in the modification reaction include organic peroxides. Typical examples include alkyl peroxides, aryl peroxides, acyl peroxides, ketone peroxides, peroxyketals, peroxycarbonates, peroxyesters, and hydroperoxides. Various selections can be made depending on conditions and reaction time. In the case of the melt graft reaction by the twin screw extruder described above, alkyl peroxide, peroxyketal, and peroxyester are preferable. Particularly preferred are di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxy-hexyne-3, dicumyl peroxide, and the like.
The modified polyolefin resin as described above is typically a polyolefin resin modified with maleic anhydride, and examples include Mitsui Chemicals Admer, Mitsubishi Chemical Modic, and Nippon Polyethylene Adtex.
A thermoplastic elastomer may be further added to the modified polyolefin resin described above. The modified polyolefin resin utilizes the reactivity with an unsaturated carboxylic acid derivative component derived from a grafted unsaturated carboxylic acid or acid anhydride or ester thereof, and a polymer containing various metals or various functional groups. Adhesiveness is imparted. Unlike adhesion by such a reaction, by blending various thermoplastic elastomers, the residual stress generated when laminating this graft-modified polyolefin resin is released and viscoelastic adhesion is improved. Is possible. Such thermoplastic elastomers include Mitsui Chemicals Tuffmer, Mitsubishi Chemical Zelas, Montell Catalloy, Mitsui Chemicals Notio, and styrene elastomers, especially hydrogenated styrene elastomers (AK elastomer Toughtech, Kuraray Septon / Hibler. , JSR Dynalon, Sumitomo Chemical Espolex, Kraton Polymer Kraton G, etc.) are preferred. Moreover, you may mix | blend various additives, such as a flame retardant, a slip agent, an antiblocking agent, antioxidant, a light stabilizer, a tackifier, for example.

As the adhesive, a polyester polyol-based adhesive composition having the contents described in the adhesive layer B1 can be used. However, since there is a risk of swelling due to electrolyte solution or hydrolysis due to hydrofluoric acid, when using an adhesive in this application, it is necessary to design a composition such as using a base material that is difficult to hydrolyze or improving the crosslinking density. is there.
For example, as a technique for improving the crosslinking density of a polyester polyol adhesive composition, dimer fatty acid or its ester or its hydrogenated product, or dimer fatty acid or its ester or its hydrogenated reducing glycol is used as the polybasic acid. Is mentioned. Dimer fatty acid is a dimerization of various unsaturated fatty acids, and its structure includes acyclic, monocyclic, polycyclic, and aromatic ring types. Polyester used in this adhesive The polybasic acid that is a raw material of the polyol is not particularly limited. There are no particular restrictions on the unsaturated fatty acid that is the starting material for the dimer fatty acid, and there are monounsaturated fatty acids, diunsaturated fatty acids, triunsaturated fatty acids, tetraunsaturated fatty acids, pentaunsaturated fatty acids, hexaunsaturated fatty acids, etc. It can be used as appropriate. Examples of monounsaturated fatty acids include crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, and nervonic acid. Examples of diunsaturated fatty acids include linoleic acid, eicosadienoic acid, and docosadienoic acid. Examples of the triunsaturated fatty acid include linolenic acid, vinolenic acid, eleostearic acid, mead acid, dihomo-γ-linolenic acid, and eicosatrienoic acid. Examples of tetraunsaturated fatty acids include stearidonic acid, arachidonic acid, eicosatetraenoic acid, and adrenic acid. Examples of the pentaunsaturated fatty acid include boseopentaenoic acid, eicosaventaenoic acid, ozbond acid, sardine acid, and tetracosaventaenoic acid. Examples of the hexaunsaturated fatty acid include docosahexaenoic acid and nisic acid. The combination of unsaturated fatty acids when dimerizing unsaturated fatty acids may be any combination. This bulky hydrophobic unit of dimer fatty acid improves the crosslink density as an adhesive.
A dibasic acid such as that used in ordinary polyester polyols may be introduced using the dimer fatty acid as an essential component. Examples of the dibasic acid include aliphatics such as succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid and brassic acid, and aromatics such as isophthalic acid, terephthalic acid and naphthalenedicarboxylic acid. It is possible to select from a family.

  As the main agent (polyester polyol) of the adhesive used in the present invention, ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol are preferable. And components obtained by using one or more of an aliphatic diol such as dodecanediol, an alicyclic system such as cyclohexanediol, hydrogenated xylylene glycol, and an aromatic diol such as xylylene glycol. Moreover, the polyester urethane polyol which extended | stretched the hydroxyl group of the both terminals of this polyester polyol using the isocyanate compound single-piece | unit or the adduct body, burette body, or isocyanurate body which consists of at least 1 type of isocyanate compound etc. are mentioned. Examples of the isocyanate compound include 2,4- or 2,6-tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2,2,4- or 2, Examples include 4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and isopropylidene dicyclohexyl-4,4′-diisocyanate. In addition, the isocyanate component described later can also be used as a chain extender for polyester polyol.

As the curing agent for the main agent, it is possible to use the same type of isocyanate compound used as the chain extender of the polyester polyol, and although it is repeated, 2,4- or 2,6-tolylene diisocyanate, xylylene Range isocyanate, 4,4'-diphenylmethane diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate , Isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isopropylidene dicyclohexyl-4,4′-diisocyanate, etc. Single bets compound or adduct of at least one isocyanate compound selected from the isocyanate compound, biuret body, isocyanurate products thereof. Furthermore, for the purpose of improving the resistance to electrolytic solution (especially solubility / swellability in electrolytic solution), polyisocyanate alone or a mixture selected from crude tolylene diisocyanate, crude (or polymeric) diphenylmethane diisocyanate, or adducts thereof. It is effective to use. The use of these curing agents leads to improvement in solubility and swelling property by improving the crosslink density of the adhesive coating film, and the urethane group concentration is increased, so that the corrosion prevention treatment layer D1 and the sealant layer F1. Improvement in adhesion is also expected. The use of the above-mentioned crude tolylene diisocyanate or crude (or polymeric) diphenylmethane diisocyanate as a chain extender of the above-described polyester polyol can be said to be a suitable material for use as an exterior material for a lithium battery.
The ratio of the main agent and the curing agent, which is an adhesive composition, is preferably 1 to 100 parts by mass of the curing agent with respect to 100 parts by mass of the main agent. If the amount is less than 1 part by mass, the performance may not be exhibited in terms of adhesion and electrolyte resistance. If the amount is more than 100 parts by mass, an excess of isocyanate groups will be present, which may affect the adhesive film quality due to the residual unreacted substances and the hardness. More preferably, it is the range of 5-50 mass parts.
Moreover, it is also possible to mix | blend the carbodiimide compound, oxazoline compound, epoxy compound, phosphorus compound, silane coupling agent, etc. for adhesion promotion mentioned above.

<Heat seal layer F1>
The heat seal layer F1 is a layer that is bonded to the aluminum foil layer C1 via the adhesive layer E1, and is required to be sealed by heat sealing of the lithium ion battery exterior material.
The material constituting the heat seal layer F1 is generally low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α olefin copolymer, homo, block or random polypropylene, propylene-α olefin copolymer. Examples thereof include polyolefin resins such as coalescence, ethylene-vinyl acetate copolymers, ethylene- (meth) acrylic acid copolymers, esterified products thereof, or ionic cross-linked products.
The heat seal layer F1 may be composed of a single layer made of any one of the above-mentioned resins or a blend of two or more of them, and may form a multilayer structure according to other required performance required for the sealant. It doesn't matter. Examples of this multilayer structure include interposing a resin having gas barrier properties such as a part of ethylene-vinyl acetate copolymer or a completely saponified product, a part of polyvinyl acetate copolymer or a completely saponified product.

<Method for producing multilayer film for molded member>
Although the multilayer film for molded members having the configuration shown in FIG. 2 can be produced by, for example, a production method having the following steps (1) to (3), it is not limited thereto.
Step (1): A step of obtaining a first laminate in which an aluminum foil layer C1 and a corrosion prevention treatment layer D1 are laminated by performing a corrosion prevention treatment on the aluminum foil.
Step (2): The aluminum foil layer C1 side of the first laminate and the base material are bonded together using an adhesive, and the base material layer A1, the adhesive layer B1, the aluminum foil layer C1, and the corrosion prevention treatment. The process of obtaining the 2nd laminated body by which layer D1 was laminated | stacked.
Process (3): The process of laminating | stacking the heat seal layer F1 on the corrosion prevention process layer D1 side of said 2nd laminated body using a thermoadhesive resin or an adhesive agent.

(Process (1))
Examples of the corrosion prevention treatment for the aluminum foil include the above-described degreasing treatment, hydrothermal alteration treatment, anodizing treatment, chemical conversion treatment, or a coating type corrosion prevention treatment in which a coating agent having corrosion prevention performance is applied.
For degreasing treatment, annealing method, spray method or dipping method, for hydrothermal conversion treatment or anodizing treatment, dipping method, for chemical conversion treatment, select dipping method, spray method, coating method etc. according to the type of chemical conversion treatment Is possible.
Various coating methods such as gravure coating, reverse coating, roll coating, and bar coating can be used as the coating method of the coating agent having corrosion prevention performance.
As shown in FIG. 1, the corrosion prevention treatment layer D1 may be provided only on one side or both sides of the aluminum foil layer C1, but at least on the adhesive layer E1 side (inner layer side) of the aluminum foil layer C1. It is necessary to provide it.
As described above, the corrosion prevention treatment layer D1 is preferably provided so that the mass per unit area is within the range of 0.005 to 0.200 g / m ² .
When drying cure is required, the base material temperature can be in the range of 60 ° C. to 300 ° C. depending on the drying conditions of the corrosion prevention treatment layer to be used. The thickness of the corrosion prevention treatment layer D1 is preferably 0.1 to 0.2 μm when dry. These layers are baked at 150 to 200 ° C. in a drying unit to produce a first laminate in which the aluminum foil layer C1 and the corrosion prevention treatment layer D1 are laminated.

(Process (2))
In the step (2), the aluminum foil layer C1 side of the first laminate obtained in the step (1) and the base material are bonded together using an adhesive, and the base material layer A1, the adhesive layer B1, and the aluminum are bonded together. A second laminate in which the foil layer C1 and the corrosion prevention treatment layer D1 are laminated is obtained.
As the adhesive, a polyurethane-based adhesive in which a main agent composed of a polyol such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol as described in the above-described adhesive layer B1 is combined with a bifunctional or higher isocyanate compound. Agents are preferred.
As a bonding method, a dry lamination method is preferably used.

(Process (3))
In the step (3), a heat seal layer F1 is laminated on the corrosion prevention treatment layer D1 side of the second laminate obtained in the step (2) by using a heat adhesive resin or an adhesive, and a base material layer A laminate (multilayer film for a molded member) in which A1, an adhesive layer B1, an aluminum foil layer C1, a corrosion prevention treatment layer D1, an adhesive layer E1, and a heat seal layer F1 are laminated is obtained.
Examples of the heat-adhesive resin and the adhesive include those described in the above-described adhesive layer E1.
As a bonding method, it is preferable to use a dry lamination or extrusion lamination technique. In the case of using the dry laminating method, a multilayer film for a molded member is manufactured by laminating both the second laminate and the heat seal layer with a heat adhesive resin or an adhesive. When the extrusion laminating method is used, a multilayer film for a molded member is manufactured by extruding and laminating a heat-adhesive resin layer on the corrosion prevention treatment layer D1 of the second laminate, and further laminating a heat seal layer.

After the step (3), a step of applying a slip material and / or an antiblocking material to the outermost layer and / or the innermost layer of the obtained laminate may be performed as necessary.
By applying the slip material and / or the anti-blocking material, the coefficient of static friction can be lowered, and the molding performance is improved.
The slip agent and / or anti-blocking agent is preferably dissolved and dispersed in a solvent. Application | coating can be implemented with a well-known coating method.

[Multilayer film for sealing members]
<Base material layer A2>
As the base material layer A2, a resin layer having a single layer or a multi-layer structure including a single layer or a multi-layer structure that does not include a stretched polyamide film is used.
As described above, the material of the base material layer is strongly related to the molding performance of the lithium ion battery exterior material, and the most preferable base material layer includes a stretched polyamide film when attention is paid to the molding performance. However, the stretched polyamide film has low resistance to hydrofluoric acid generated from the electrolyte solution of the lithium ion battery, and it is common to provide an acid resistance-imparting layer. In order to maintain and improve the molding performance while having such problems, a single-layer or multi-layer structure including a stretched polyamide film is optimal. Conventionally, a multilayer film using such a base material layer has been used for both a molded member and a sealing member. However, in the present invention, the molded member and the sealing member are distinguished from each other. For the multilayer film for use, since the molding performance can be ignored, the choice of the material of the base material layer is widened.
As the base material layer A2, it is preferable to use a resin layer that does not include a stretched polyamide film and that improves acid resistance on the exterior side of the lithium ion battery. More preferably, the resin layer also improves heat resistance against heat generated during heat sealing. Examples of such a resin layer include a stretched polyester film, a vinylidene chloride film, a polycarbonate film, a polybutylene terephthalate film, a polytetrafluoroethylene film, a phenol resin film, a melanin resin film, an epoxy resin film, and an unsaturated polyester resin film. Is mentioned. Among these, a stretched polyester film is preferable.

The thickness of the base material layer A2 is preferably 4 μm or more and more preferably 5 μm or more in terms of improving the piercing property and insulation. Further, in terms of thinning and high heat dissipation, it is preferably 25 μm or less, and more preferably 15 μm or less.
As described above, the base material layer used in the multilayer film for a molding site is preferably a stretched polyamide film or a film obtained by adding an acid resistance-imparting layer to the stretched polyamide film. The molding performance has a strong positive correlation with the thickness of the stretched polyamide film, and in order to obtain high moldability, the stretched polyamide film becomes thicker, and consequently the lithium battery becomes thicker. Similarly, for a film obtained by adding an acid-proofing layer to a stretched polyamide film, it is necessary to add an acid-proofing layer to a thick stretched polyamide file in order to achieve both high molding performance and acid resistance. This increases the thickness of the layer, and hence the thickness of the lithium ion battery. Conventionally, since the same multilayer film is used for both the molded member and the sealing member, it was inevitable to increase the thickness of the lithium ion battery in order to ensure molding performance and acid resistance. For the member and for the sealing member, the molding performance of the multilayer film for the sealing member can be ignored. Therefore, the base material layer can be made thinner and the lithium battery can be made thinner.
Various additives such as an acid resistance imparting agent, a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, and a light stabilizer are provided on the outermost layer surface (surface opposite to the adhesive layer B2 side) of the base material layer A2. A tackifier or the like may be applied. Examples of the acid resistance-imparting agent, slip agent, and anti-blocking agent are the same as those described above for the base material layer A1.

<Adhesive layer B2>
The adhesive layer B2 is a layer that improves the adhesion between the base material layer A2 and the metal foil layer C2.
Examples of the material constituting the adhesive layer B2 include the same materials as those described for the adhesive layer B1.

<Metal foil layer C2>
Aluminum foil is lightweight and rich in malleability, has excellent workability such as molding and lamination, is excellent in water vapor and other barrier properties, and is relatively inexpensive and economical as a general-purpose metal foil. Therefore, in the multilayer film for molded members, the aluminum foil layer C1 is used as the metal foil layer. However, in the multilayer film for sealing members, workability is not required because cold forming is not performed. For example, aluminum, stainless steel foil, iron foil, copper foil, nickel foil, soft, hard aluminum foil or the like can be used. The properties required for the metal foil layer C2 of the multilayer film for a sealing member are pinhole resistance, barrier properties, and acid resistance, and it is preferable to use an aluminum foil, a stainless steel foil, or the like in terms of being excellent in these properties. But this is not the case.
The metal foil is preferably subjected to a degreasing treatment. As this degreasing process, the thing similar to what was mentioned by description of the said aluminum foil layer C1 is mentioned.
The degreasing treatment may be performed on one side or both sides of the metal foil.
The thickness of the metal foil layer C2 is preferably 30 μm or less in order to contribute to the thinning of the lithium battery while ensuring pinhole resistance, barrier properties, and workability. By using a lithium battery packaging material having such a structure, it is easy to process a laminate, etc., and it is excellent in water vapor and other barrier properties, and also produces an economical lithium battery exterior material with high productivity. be able to.

<Corrosion prevention treatment layer D2>
The corrosion prevention treatment layer D2 is basically a layer provided to prevent corrosion of the metal foil layer C2 due to the electrolytic solution or hydrofluoric acid.
Examples of the corrosion prevention treatment used for the corrosion prevention treatment layer D2 include the same ones as mentioned in the explanation of the corrosion prevention treatment layer D1.
Similarly to the corrosion prevention treatment layer D1, the corrosion prevention treatment layer D2 is preferably provided so that the mass per unit area is within the range of 0.005 to 0.200 g / m ² . It is more preferable to provide it within the range of 100 g / m ² .

<Adhesive layer E2>
The adhesive layer E2 is a layer used when the corrosion prevention treatment layer D2 and the sealant layer F1 are bonded together.
Examples of the material constituting the adhesive layer E2 include the same materials as those described in the description of the adhesive layer E1.

<Heat seal layer F2>
The heat seal layer F2 is a layer that is bonded to the metal foil layer C2 through the adhesive layer E2, and is required to be sealed by heat sealing of the lithium ion battery exterior material.
As a material which comprises the heat seal layer F1, the thing similar to what was mentioned by description of the said heat seal layer F1 is mentioned.

<The manufacturing method of the multilayer film for sealing members>
The multilayer film for a sealing member having the configuration shown in FIG. 3 can be manufactured by, for example, a manufacturing method having the following steps (1 ′) to (3 ′), but is not limited thereto.
Step (1 ′): a step of performing a corrosion prevention treatment on the metal foil to obtain a first laminate in which the metal foil layer C2 and the corrosion prevention treatment layer D2 are laminated.
Step (2 '): The metal foil layer C2 side of the first laminate and the base material are bonded together using an adhesive, and the base material layer A2, the adhesive layer B2, the metal foil layer C2, and the corrosion prevention The process of obtaining the 2nd laminated body by which the process layer D2 was laminated | stacked.
Step (3 ′): a step of laminating a heat seal layer F2 on the corrosion prevention treatment layer D2 side of the second laminate using a heat adhesive resin or an adhesive.
Steps (1 ′) to (3 ′) can be carried out in the same procedure as steps (1) to (3) mentioned in the description of the method for producing a molded member.
After the step (3 ′), a step of applying a slip material and / or an antiblocking material to the outermost layer and / or the innermost layer of the obtained laminate may be performed as necessary.

≪Lithium ion battery≫
The lithium ion battery of the present invention comprises the lithium ion battery exterior material of the present invention.
As the configuration of the lithium ion battery of the present invention, a known configuration can be adopted except that the lithium ion battery exterior material of the present invention is used as the exterior material. Moreover, the manufacturing method of the lithium ion battery of this invention can employ | adopt a well-known manufacturing method except using the lithium ion battery exterior material of this invention as an exterior material.
If an example is given, first, the multilayer film for shaping | molding members will be cold-molded, a substantially square recessed part will be formed, and a shaping | molding member will be created. At this time, the inner surface of the recess is made to be the heat seal layer F1. Next, after the battery cell (positive electrode, separator, negative electrode) is accommodated in the concave portion of the molded member, the sealing member made of the multilayer film for the sealing member is placed on the opening side of the concave portion with the heat seal layer F1 and the heat seal. The layers F2 are stacked so as to face each other, and the three sides are heat-sealed. Thereafter, an electrolyte is injected from one side remaining in a vacuum environment, and the remaining one side is finally heat-sealed to seal the inside, whereby a lithium ion battery can be obtained.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples.
Here, the material of base material layer A1, A2, aluminum foil layer C1, and metal foil layer C2 is shown among the materials used for manufacture of a lithium ion battery exterior material in each following example.

<Base material layers A1, A2>
G-1: Stretched nylon film (thickness 25 μm).
G-2: Stretched nylon film (thickness 15 μm).
G-3: Stretched polytetrafluoroethylene film (thickness 25 μm).
G-4: Stretched polytetrafluoroethylene film (thickness 12 μm).
G-5: Two-layer film of stretched nylon film (thickness 25 μm) / stretched polytetrafluoroethylene film (thickness 12 μm).
G-6: Two-layer film of stretched nylon film (thickness 15 μm) / stretched polytetrafluoroethylene film (thickness 12 μm).

<Aluminum foil layer C1>
H-1: Aluminum foil (thickness 40 μm).
H-2: Aluminum foil (thickness 20 μm).

<Metal foil layer C2>
I-1: Aluminum foil (thickness 40 μm).
I-2: Aluminum foil (thickness 20 μm).
I-3: Stainless steel foil (thickness 20 μm).
I-4: Copper foil (thickness 20 μm).

<Example 1>
In the following procedure, a molded member and a sealing member were prepared and combined to form a lithium ion battery exterior material. Moreover, the following evaluation was performed.
[Production of multilayer film for molded parts]
Corrosion prevention treatment comprising a cerium oxide rare earth oxide sol and a polyacrylic acid anionic polymer is performed on the aluminum foil layer C1 (H-1) by a coating technique, and a polyallylamine cationic polymer as an overcoat. Was similarly formed by a coating technique to provide a corrosion prevention treatment layer D1. A base material layer A1 (G-1) was laminated on the outer side of the aluminum foil layer C1 provided with the corrosion prevention treatment layer D1 by a dry laminating method using an adhesive B1. As the adhesive B1, a polyester urethane dry laminate adhesive was used. Thereafter, an adhesive layer E1 (a layer made of an acid-modified polyolefin resin) and a heat seal layer F1 (an innermost layer made of a polypropylene resin) are formed on the inner layer side (at least the side on which the corrosion prevention treatment layer D1 is formed) by an extrusion laminating method. Then, a heat treatment process was performed in a subsequent process. Furthermore, the multilayer film for molding members used as the basis of a molding member was created by apply | coating a slip material to the outermost layer and innermost layer of the obtained laminated body.
[Production of molded parts by cold forming]
The obtained multilayer film for molded member was formed into a molded member by forming a recess at a drawing depth of 5 mm using a cold forming apparatus capable of adjusting a 50 × 70 mm size and a drawing depth of 3 to 10 mm.
[Production of multilayer film for sealing member]
Through the same process as the production of the multilayer film for molded members, except that I-2 was used instead of H-1 and G-4 was used instead of G-1, a multilayer film for sealing member was produced, The obtained multilayer film for sealing members was used as a sealing member as it was.

[Molding performance evaluation]
The molding performance of the above-mentioned multilayer film for molded members was evaluated using a cold molding apparatus that can be adjusted to a size of 50 × 70 mm and a drawing depth of 3 to 10 mm. The results are shown in Table 1.
A: Molding performance of 6 mm or more.
○: Molding performance of 5 to 6 mm.
X: Molding performance of 5 mm or less.
Among the above, evaluation of (circle) or (double-circle) was determined to have sufficient shaping | molding performance as a lithium ion battery exterior material. The molding performance is evaluated based on the drawing depth that can be molded without defects such as cracks. For example, a molding performance of 6 mm or more indicates that molding can be performed without any defects of 6 mm or more.

[Acid resistance evaluation]
3 cc of an electrolytic solution (diethyl carbonate + dimethyl carbonate + ethyl carbonate + fluorine-containing lithium salt) is applied to the outermost layer of the lithium ion battery exterior material (the base material layer A1 side of the molding member and the base material layer A2 side of the sealing member). Further, 3 cc of tap water was dropped, and the whitened (dissolved) state of the film after being left overnight was observed visually. The results are shown in Table 1.
○: No erosion (no change in surface condition).
Δ: There is an erosion site.
X: There is full erosion.
Among the above, evaluation of (circle) was determined to have sufficient acid resistance (electrolytic solution resistance) as a lithium ion battery exterior material, and (triangle | delta) was determined to have a certain amount of acid resistance (electrolytic solution resistance).

[Thickness evaluation]
The total thickness of the lithium ion battery exterior material (thickness in a state in which the molded member and the sealing member are overlapped) was measured. The results are shown in Table 1.
A: Thinner than the current product.
○: Thin in current product.
Δ: Normal thickness of the current product.
X: Thickness exceeding the normal thickness of the current product.
Among the above, evaluation of (circle) or (double-circle) was determined to be thin enough as a lithium ion battery exterior material. The thickness of the current product is the thickness of Comparative Example 2 (thickness using G-2 and H-1 or I-1), G-1 to G-6, H-1 to H-2, The combination of I-1 to I-4 was judged to be thicker or thinner than the current product.

[Heat dissipation evaluation]
After the battery cell (positive electrode, separator, negative electrode) is accommodated in the concave portion of the molded member of the lithium ion battery exterior material, a sealing member made of a multilayer film for a sealing member is provided on the opening side of the concave portion, and the heat seal layer F1. And heat seal layer F2 were stacked so as to face each other, and three sides were heat sealed. After that, electrolyte solution (diethyl carbonate + dimethyl carbonate + ethyl carbonate + fluorine-containing lithium salt) was injected from one side remaining in a vacuum environment, the remaining one side was finally heat sealed, and the inside was sealed to make a lithium ion battery. Created.
About this lithium ion battery, the exterior surface temperature at the time of battery use was measured.
A: Heat dissipation exceeding the current product.
○: Excellent heat dissipation in the current product.
Δ: Normal heat dissipation of the current product.
×: Heat dissipation that does not reach the current product.
Among the above, evaluation of (circle) or (double-circle) was determined to have sufficient heat dissipation as a lithium ion battery exterior material. The current product here corresponds to Comparative Example 2.

<Examples 2-12, Comparative Examples 1-8>
A lithium ion battery exterior material was obtained in the same manner as in Example 1 except that the combinations of the base material layers A1, A2, the aluminum foil layer C1, and the metal foil layer C2 were changed to the combinations shown in Table 1.
Each example was evaluated in the same manner as in Example 1 for molding performance, acid resistance, thickness, and heat dissipation. The results are shown in Table 1.

  As shown in the above results, in Examples 1 to 12, lithium ion battery exterior materials having high molding performance as compared with the comparative example and having thinness, heat dissipation property, and acid resistance were obtained.

  In the present invention, by using two different types of multilayer films for molded member multilayer film and sealing member multilayer film, the molding performance required for the lithium ion battery exterior material is maintained, and the lithium ion battery exterior side is maintained. Thus, a lithium battery exterior material having acid resistance, thinness and high heat dissipation can be obtained. Therefore, the lithium ion battery can also be thinned.

1: Molding member 2: Sealing member 10: Lithium ion battery exterior material A1: Base material layer B1: Adhesion layer C1: Aluminum foil layer D1: Corrosion prevention treatment layer E1: Adhesion layer F1: Heat seal layer A2: Base material layer B2: Adhesive layer C2: Metal foil layer D2: Corrosion prevention treatment layer E2: Adhesive layer F2: Heat seal layer

Claims (4)

A lithium-ion battery exterior material comprising at least a molding member having a recess formed by cold forming, and a sealing member for sealing the opening of the recess,
The molded member comprises a multilayer film for molded members having a laminate structure in which a base material layer A1, an adhesive layer B1, an aluminum foil layer C1, a corrosion prevention treatment layer D1, an adhesive layer E1, and a heat seal layer F1 are sequentially laminated.
The sealing member comprises a multilayer film for a sealing member having a laminate structure in which a base material layer A2, an adhesive layer B2, a metal foil layer C2, a corrosion prevention treatment layer D2, an adhesive layer E2, and a heat seal layer F2 are sequentially laminated. And at least the base material layer A1 has a single layer or multi-layer structure including a stretched polyamide film, and the base material layer A2 has a single layer or a multi-layer structure not including a stretched polyamide film. Lithium ion battery exterior material.   The lithium ion battery exterior material of Claim 1 whose thickness of the said metal foil layer C2 is 30 micrometers or less.   The lithium ion battery exterior material according to claim 1 or 2, wherein the thickness of the base material layer A2 is 25 µm or less.   A lithium ion battery comprising the lithium ion battery exterior material according to claim 1.

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