JP6672587B2 - Exterior materials for lithium batteries - Google Patents

Description

  The present invention relates to an exterior material for a lithium battery.

As secondary batteries for consumer use used in personal digital assistants such as personal computers and mobile phones, video cameras, and the like, lithium-ion batteries that can be made ultrathin and small in size while having high energy have been actively developed.
As an exterior material for a lithium-ion battery (hereinafter, sometimes simply referred to as an “exterior material”), a multilayer structure is used instead of a conventional metal can because of its light weight and the ability to freely select the battery shape. Is used. In addition, exterior materials using such a laminate film are not only flexible in battery shape, but also lightweight, have high heat dissipation, and are low in cost. Attempts have also been made to apply batteries to electric vehicles.

  The laminate film has a structure in which a sealant layer (heat-fusible film) is laminated on one side of a metal foil layer such as an aluminum foil via an adhesive layer, and is formed on the other side via an adhesive layer. A configuration in which material layers (plastic films) are laminated (base layer / adhesive layer / metal foil layer / adhesive layer / sealant layer) is generally used.

Lithium ion batteries using a laminate film type exterior material include, for example, a positive electrode material, a negative electrode material, and a separator as a battery body portion in a molded product obtained by deep drawing the above-described laminated film by cold molding (deep drawing molding). At the same time, an electrolyte layer made of an electrolyte solution or a polymer gel impregnated with the electrolyte solution is accommodated, and formed by heat sealing with heat sealing.
As the electrolyte, an electrolyte obtained by dissolving a lithium salt in an aprotic solvent (propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc.) is used.
The electrolyte has high permeability to the sealant layer. Therefore, in a lithium ion battery, the electrolyte solution that has permeated the sealant layer has reduced the lamination strength between the metal foil layer and the sealant layer, and eventually the electrolyte solution may leak. Lithium salts such as LiPF ₆ and LiBF ₄ which are electrolytes may generate hydrofluoric acid by a hydrolysis reaction. Hydrofluoric acid causes corrosion of the metal surface and lowers the laminate strength between the layers of the laminate film. Therefore, the exterior material is required to have a corrosion prevention performance against an electrolytic solution and hydrofluoric acid.

  In response to such demands, as a packaging material having sufficient electrolyte solution resistance, for example, Patent Document 1 discloses a carboxy resin that suppresses a temporal decrease in lamination strength between a sealant layer and a metal foil layer due to an electrolyte solution. An exterior material is disclosed in which a sealant layer and a metal foil layer are adhered to each other via a layer (adhesive layer) made of an adhesive containing a polyolefin resin having a group and a polyfunctional isocyanate compound.

JP 2010-92703 A

  However, as described in Patent Document 1, a combination of a polyolefin resin having a carboxy group and a polyfunctional isocyanate compound is a system having a low reaction rate. When the reaction rate is low, it is necessary to lengthen the aging time in order to sufficiently bond the sealant layer and the metal foil layer.

Further, since the adhesive layer described in Patent Literature 1 forms a crosslinked structure, it can function as an insulating layer in, for example, sealing with an electrode tab or a degassing sealing step in battery manufacturing. .
However, if it is difficult to sufficiently bond the sealant layer and the metal foil layer, for example, when the exterior material is molded into a pocket shape by cold molding, the stress at the time of molding causes an interface between the sealant layer and the metal foil layer. There was a case where a minute floating was generated in a concentrated manner. As a result, the insulating property may be reduced based on the minute floating.

By the way, a corrosion prevention treatment layer may be provided on the surface of the metal foil layer on the sealant layer side for the purpose of imparting electrolytic solution resistance. In this case, the corrosion prevention treatment layer and the sealant layer adhere via the adhesive layer.
However, as described above, hydrofluoric acid or the like generated by the hydrolysis of the lithium salt serving as the electrolyte may penetrate between the corrosion prevention treatment layer and the adhesive layer, resulting in a decrease in laminate strength.

  The present invention has been made in view of the above circumstances, and exhibits a high laminating strength even with a short aging time, has excellent electrolytic solution resistance, and can ensure insulation even when cold-formed. The purpose is to provide materials.

The present invention has the following aspects.
[1] A base material layer, a first adhesive layer, a metal foil layer, a single-layer or multi-layer corrosion prevention treatment layer, a second adhesive layer, and a sealant layer are arranged in this order. The corrosion prevention treatment layer is provided on at least the second adhesive layer side, and at least a layer in contact with at least the second adhesive layer is at least selected from the group consisting of a cationic polymer and an anionic polymer. The layer containing one kind of polymer, and the corrosion prevention treatment layer is formed by subjecting the metal foil layer to at least one kind of treatment selected from the group consisting of a degreasing treatment, a hydrothermal modification treatment, an anodic oxidation treatment, and a chemical conversion treatment. The exterior material for a lithium battery, wherein the second adhesive layer includes a compound reactive with the polymer contained in the layer in contact with the second adhesive layer.
[2] The corrosion prevention treatment layer contains a cationic polymer in a layer in contact with the second adhesive layer, and the compound having reactivity with the cationic polymer contained in the second adhesive layer is a polyfunctional isocyanate compound The exterior material for a lithium battery according to [1], wherein the exterior material is at least one selected from the group consisting of glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group.
[3] An ionic polymer complex in which the cationic polymer is polyethyleneimine, a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin having a primary amine grafted on an acrylic main skeleton, polyallylamine or a derivative thereof The exterior material for a lithium battery according to [2], which is at least one member selected from the group consisting of aminophenol and aminophenol.
[4] The corrosion prevention treatment layer includes an anionic polymer in a layer in contact with the second adhesive layer, and a compound having a reactivity with the anionic polymer contained in the second adhesive layer is a glycidyl compound or oxazoline. The exterior material for a lithium battery according to [1], which is at least one selected from the group consisting of a compound having a group and a carbodiimide compound.
[5] A copolymer in which the anionic polymer is a polymer having a carboxy group, and the polymer is a copolymer of poly (meth) acrylic acid or a salt thereof, or a monomer mixture containing (meth) acrylic acid or a salt thereof. The exterior material for a lithium battery according to [4], wherein
[6] The exterior material for a lithium battery according to any one of [1] to [5], wherein the second adhesive layer further includes an acid-modified polyolefin resin.
[7] The method according to any one of [1] to [6], wherein a single-layer or multi-layer corrosion prevention treatment layer is provided between the first adhesive layer and the metal foil layer. Exterior material for lithium batteries.

  ADVANTAGE OF THE INVENTION The exterior material for lithium batteries of this invention expresses high lamination strength even with a short aging time, is excellent in electrolytic solution resistance, and can secure insulation even if cold-formed.

FIG. 1 is a cross-sectional view illustrating an example of a packaging material for a lithium battery according to the present invention.

Hereinafter, as an example of the exterior material for a lithium battery of the present invention, an exterior material for a lithium battery (hereinafter simply referred to as “exterior material”) 10 shown in FIG. 1 will be described. In each drawing used in the following description, the scale of each member is appropriately changed in order to make each member a recognizable size.
As shown in FIG. 1, the exterior material 10 of the present embodiment includes a base material layer 11, a first adhesive layer 12, a metal foil layer 13, a corrosion prevention treatment layer 14, and a second adhesive layer 15 and a sealant layer 16 are formed of a laminated body laminated in this order.
The exterior material 10 uses the base material layer 11 as the outermost layer and the sealant layer 16 as the innermost layer.

"Base material layer"
The base material layer 11 plays a role of imparting heat resistance in a heat sealing step when manufacturing a lithium battery, and suppressing generation of pinholes that may occur during molding and distribution. In particular, in the case of an exterior material of a lithium battery for a large use, scratch resistance, chemical resistance, insulation properties, and the like can be imparted.

As the base material layer 11, a resin film formed of an insulating resin is preferable.
Examples of the resin film include a stretched or unstretched film such as a polyester film, a polyamide film, and a polypropylene film.
The base material layer 11 may be a single layer or two or more layers. For example, the base material layer 11 may be a single-layer resin layer made of any one of the above-described resin films, or a multi-layer resin layer in which two or more of the above-described resin films are laminated. Good. Examples of these resin layers include a stretched or non-stretched polyamide film, a stretched or non-stretched polyester film, and a two-layer film of a stretched polyamide film and a stretched polyester film. For example, a co-extruded multilayer biaxially stretched multilayer film obtained by co-extrusion of polyester and polyamide using an adhesive resin and then performing biaxial stretching may be used as the base layer 11.

  As the base material layer 11, a stretched polyamide film is preferable in terms of excellent moldability and heat resistance. Further, as the base material layer 11, a stretched polyester film is preferable in terms of excellent acid resistance. Further, as the base material layer 11, a laminated film of a stretched polyamide film and a stretched polyester film is preferable in terms of easily satisfying moldability, heat resistance, and acid resistance.

The thickness of the base material layer 11 is preferably 6 μm or more, more preferably 10 μm or more, from the viewpoints of moldability, heat resistance, pinhole resistance, and insulation. In addition, the thickness of the base material layer 11 is preferably 60 μm or less, and more preferably 45 μm or less, in terms of thinning and high heat dissipation.
When the base material layer 11 is a resin layer having a multilayer structure, the thickness is the entire thickness.

On the outermost surface of the base material layer 11 (the surface opposite to the first adhesive layer 12 side), an acid resistance imparting agent, a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, a light stabilizer, a tackifier Various additives such as an agent 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. Can be
Examples of the slip agent include fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, ethylenebisoleic acid amide, and ethylenebiserucic acid amide.
As the anti-blocking agent, various filler-based anti-blocking agents such as silica are preferable.
One of these additives may be used alone, or two or more thereof may be used in combination.

"First adhesive layer"
The first adhesive layer 12 is a layer that bonds the base material layer 11 and the metal foil layer 13.
The first adhesive layer 12 can be formed by using a known adhesive used for laminating a resin film and a metal foil. Examples of the adhesive include a polyurethane-based adhesive containing a main agent composed of a polyol such as a polyester polyol, a polyether polyol, an acrylic polyol, and a carbonate polyol, and a curing agent composed of a bifunctional or more isocyanate compound. By causing the curing agent to act on the main agent, a polyurethane-based resin is formed.

As the polyester polyol, those obtained by reacting at least one kind of polybasic acid and at least one kind of diol can be used.
Examples of the polybasic acids include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, aliphatic dibasic acids such as brassic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. And dibasic acids such as aromatic dibasic acids.
Examples of the diol include aliphatic diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol, cyclohexanediol, and water. Examples include alicyclic diols such as added xylylene glycol, and aromatic diols such as xylylene glycol.

Further, as the polyester polyol, a hydroxyl group at both ends of the polyester polyol, a simple substance of an isocyanate compound, or a polyester urethane polyol having a chain extended using an adduct, a burette or an isocyanurate of at least one isocyanate compound, or the like. No.
Examples of the isocyanate compound include 2,4- or 2,6-tolylene diisocyanate (TDI) or a hydrogenated product thereof, crude TDI, xylylene diisocyanate (XDI) or a hydrogenated product thereof, hexamethylene diisocyanate (HDI), , 4'-diphenylmethane diisocyanate (MDI) or hydrogenated product thereof, crude MDI, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6- Hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate, isopropylidene dicycl Such as diisocyanate such as hexyl-4,4'-diisocyanate, and the like.
One of these isocyanate compounds may be used alone, or two or more thereof may be used in combination.

  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 having the above-mentioned isocyanate compound acted as a chain length extender.

  Examples of the acrylic polyol include a copolymer containing poly (meth) acrylic acid as a main component. Examples of the copolymer include a hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, and a methyl group, an ethyl group, an n-propyl group, an i-propyl group as an alkyl group. An alkyl (meth) acrylate-based monomer which is a group, an n-butyl group, an i-butyl group, a t-butyl group, a 2-ethylhexyl group, or a cyclohexyl group, further (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 (meth) Acrylamide, amide group-containing monomers such as N-methylol (meth) acrylamide, N-phenyl (meth) acrylamide, glycidyl (meth) acrylate, (such as methoxy group, ethoxy group, butoxy group, and isobutoxy group). Glycidyl group-containing monomers such as allyl glycidyl ether, silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane and (meth) acryloxypropyltriethoxysilane, and isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate are commonly used. Polymerized ones are exemplified.

As the carbonate polyol, a product obtained by reacting a carbonate compound with a diol can be used.
As the carbonate compound, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate and the like can be used.
Examples of the diol include the diols exemplified above in the description of the polyester polyol.
Further, it is possible to use a polycarbonate urethane polyol in which the terminal hydroxyl group of the carbonate polyol is chain-extended by the above-described isocyanate compound.

  These various polyols may be used alone or in a blend of two or more, depending on the required function and performance.

Examples of the bifunctional or higher functional isocyanate compound used as a curing agent include the isocyanate compounds exemplified above in the description of the polyester polyol.
The amount of the curing agent is preferably 1 to 100 parts by mass, more preferably 5 to 50 parts by mass, per 100 parts by mass of the main agent. If the amount is less than 1 part by mass, 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, and the residual unreacted substance may affect the quality of the adhesive film or affect the hardness.

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 polyurethane-based adhesive 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 -Cyclohexylcarbodiimide, and N, N'-di-p-toluylcarbodiimide. Examples of the carbodiimide compound include a compound having a unit represented by the following general formula (1), a compound having a unit represented by the following general formula (2), and a compound having a unit represented by the following general formula (3). And the like.

  In the general formulas (1) to (3), n is an integer of 2 to 30, and preferably an integer of 3 to 20.

  Examples of the oxazoline compound include monooxazoline compounds such as 2-oxazoline, 2-methyl-2-oxazoline, 2-phenyl-2-oxazoline, 2,5-dimethyl-2-oxazoline, and 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).

  Examples of the epoxy compound include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol, sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, and trimethylolpropane. Polyglycidyl ethers of aliphatic polyols, polyglycidyl ethers of alicyclic polyols such as cyclohexanedimethanol, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, aliphatic acids such as sebacic acid, and aromatic Diglycidyl or polyglycidyl esters of polycarboxylic acids, resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p-hydroxyphenyl) propane, Diglycidyl ether or polyglycidyl ether of polyhydric phenol such as ris- (p-hydroxyphenyl) methane, 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane, N, N'-diglycidylaniline, N N-glycidyl derivatives of amines, such as N, N, N-diglycidyl toluidine, N, N, N ', N'-tetraglycidyl-bis- (p-aminophenyl) methane, triglycidyl derivatives of aminophenol, triglycidyl tris (2-hydroxyethyl) isocyanurate, triglycidyl isocyanurate, orthocresol epoxy, phenol novolak epoxy, and the like.

  As the phosphorus compound, for example, 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-t-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2- Methyl-4-ditridecylphosphite-5-t-butyl-phenyl) butane, tris (mixed mono and di-nonylphenyl) phosphite, tris Nonylphenyl) phosphite, 4,4'-isopropylidene-bis (phenyl - dialkyl phosphite), and the like.

Examples of the silane coupling agent include vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycide Xypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- Various silane coupling agents such as β (aminoethyl) -γ-aminopropyltrimethoxysilane can be used.
In addition, various additives and stabilizers may be blended according to the performance required for the adhesive.

  The thickness of the first adhesive layer 12 is preferably 1 to 10 μm, more preferably 3 to 7 μm. When the thickness is 1 μm or more, the lamination strength as an adhesive is improved. When the thickness is 10 μm or less, when the exterior material 10 is formed into a deep drawn product by cold forming, even at the drawn corner of the deep drawn product, The floating between the base material layer 11 and the metal foil layer 13 under the liquid atmosphere can be sufficiently suppressed.

"Metal foil layer"
The metal foil layer 13 has a water vapor barrier property for preventing moisture from entering the battery. Further, the metal foil layer 13 has extensibility for deep drawing.
As the metal foil layer 13, various metal foils such as aluminum and stainless steel can be used, and aluminum foil is preferable in terms of weight (specific gravity), moisture resistance, workability, and cost. The metal foil layer made of aluminum foil is also referred to as “aluminum foil layer”.

As the aluminum foil to be the metal foil layer 13, a known soft aluminum foil can be used, and an aluminum foil containing iron is preferable from the viewpoint of pinhole resistance and spreadability during molding. The content of iron in the aluminum foil (100% by mass) is preferably from 0.1 to 9.0% by mass, more preferably from 0.5 to 2.0% by mass, based on 100% by mass of the total mass of the aluminum foil. preferable. If the iron content is at least the lower limit, the pinhole resistance and spreadability will be improved. When the iron content is equal to or less than the upper limit, flexibility is improved.
The thickness of the aluminum foil layer is preferably from 9 to 200 μm, more preferably from 15 to 100 μm, from the viewpoint of barrier properties, pinhole resistance, and workability.

Although an untreated aluminum foil may be used for the metal foil layer 13, it is preferable to use an aluminum foil that has been subjected to a degreasing treatment. The degreasing treatment is roughly classified into a wet type and a dry type.
Examples of the wet type degreasing treatment include acid degreasing and alkali degreasing. Examples of the acid used for acid degreasing include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid. One of these acids may be used alone, or two or more thereof may be used in combination. In addition, various metal salts serving as a supply source of iron (III) ions and cerium (III) ions may be blended as necessary from the viewpoint of improving the etching effect of the aluminum foil. Examples of the alkali used for the alkali degreasing include a strong etching type alkali such as sodium hydroxide. In addition, a compound containing a weak alkali or a surfactant may be used. The wet type degreasing treatment is performed by a dipping method or a spray method.
Examples of the dry type degreasing treatment include a method of performing a degreasing treatment in a step of annealing aluminum. In addition to the degreasing treatment, a flame treatment, a corona treatment and the like can be mentioned. Further, a degreasing treatment for oxidatively decomposing and removing contaminants by active oxygen generated by irradiating ultraviolet rays of a specific wavelength may be employed.
The degreasing treatment may be performed on one side or both sides of the aluminum foil.

"Corrosion prevention treatment layer"
The corrosion prevention treatment layer 14 is a layer provided to prevent corrosion of the metal foil layer 13 by an electrolytic solution or hydrofluoric acid.
At least the layer in contact with the second adhesive layer contains at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer. Further, the corrosion prevention treatment layer 14 is formed by subjecting the metal foil layer 13 to at least one treatment selected from the group consisting of a degreasing treatment, a hot water transformation treatment, an anodic oxidation treatment, and a chemical conversion treatment.
When a coating layer such as the corrosion prevention treatment layer 14 is provided on the metal foil layer 13, a technique of using a silane coupling agent to improve interfacial adhesion may be generally used. In the present invention, the corrosion prevention treatment layer 14 may or may not contain a silane coupling agent. However, depending on the type of the functional group contained in the silane coupling agent to be used, the component contained in the corrosion prevention treatment layer described below and the silane coupling agent may cause a side reaction, which may adversely affect the intended reaction. is there. Therefore, when there is a possibility that the reaction may be adversely affected, it is preferable that the corrosion prevention treatment layer 14 does not contain a silane coupling agent.
Hereinafter, the degreasing treatment, the hot water conversion treatment, the anodic oxidation treatment, and the chemical conversion treatment are collectively referred to as “corrosion prevention treatment”.

Examples of the degreasing treatment include acid degreasing and alkali degreasing. Examples of the acid degreasing include a method using the above-mentioned inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid alone or a mixture thereof. In addition, as the 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 layer 13 but also the passivation of the metal Which is effective in terms of resistance to hydrofluoric acid. Examples of the alkali degreasing include a method using sodium hydroxide or the like.
Examples of the hydrothermal conversion treatment include a boehmite treatment obtained by immersing a metal foil in boiling water to which triethanolamine has been added.
Examples of the anodizing treatment include an alumite treatment.

The chemical conversion treatment includes an immersion type and a coating type.
Examples of the immersion type chemical conversion treatment include various chemical conversion treatments including, for example, chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or a mixed phase thereof. Can be The application type is a method in which a resin component is further added to a chemical conversion treatment agent used in these chemical conversion treatments, thereby forming a coating by coating. Among the chemical conversion treatments, a chromate treatment is preferred in that it has excellent corrosion resistance.

  Examples of the chromate treatment include chromate treatment using a chromium compound such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, acetyl chromate, chromium chloride, potassium chromium sulfate; Phosphoric acid chromate treatment using a phosphorus compound such as sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid and the like can be mentioned. Examples of the coating type chromate treatment include, for example, a chromate treatment using an aminated phenol polymer having units represented by the following general formulas (4) to (7).

In the general formulas (4) to (7), X is a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ¹ and R ² are the same or different and each is a hydroxy group, an alkyl group, or a hydroxyalkyl group.
Examples of the alkyl group include a straight or branched chain having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and a t-butyl group. Alkyl group.
Examples of the hydroxyalkyl group include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxy A straight-chain or branched-chain alkyl group having 1 to 4 carbon atoms in which one hydroxy group such as a butyl group, a 3-hydroxybutyl group and a 4-hydroxybutyl group is substituted.
In the general formulas (4) to (7), the alkyl group and the hydroxyalkyl group represented by X, R ¹ and R ² may be the same or different.
In the general formulas (4) to (7), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group.
The number average molecular weight of the aminated phenol polymer having the units represented by the general formulas (4) to (7) is not particularly limited, but is preferably from 500 to 1,000,000, and more preferably from 1,000 to 2.

In the case of performing the above-described chromate chromate treatment, it is preferable that the chromium compound is contained in a ratio of 0.5 to 50.0 mg in terms of chromium per 1 m ² of the surface of the metal foil layer 13, and more preferably. 1.0 to 40.0 mg. In the case where phosphoric acid chromate treatment is performed, it is preferable that the phosphorus compound is contained in a ratio of 0.5 mg to 50.0 mg in terms of phosphorus per 1 m ² of the surface of the metal foil layer 13, and more preferably. 1.0 to 40.0 mg. In the case of performing chromate treatment using an aminated phenol polymer, the aminated phenol polymer should be contained in a ratio of 1.0 to 200.0 mg per 1 m ² of the surface of the metal foil layer 13. And more preferably 5.0 to 150.0 mg.

  In addition, the coating agent used for the coating type chemical conversion treatment may contain at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer as a resin component.

The cationic polymer is a compound having excellent resistance to electrolytes and hydrofluoric acid. The cause is presumed to be that trapping fluorine ions with a cationic group (anion catcher) suppresses damage to the aluminum foil.
Examples of the cationic polymer include polymers containing an amine. Specific examples include polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, and an acrylic main skeleton having a primary amine grafted with a primary amine. Grade amine-grafted acrylic resin, polyallylamine or a derivative thereof, aminophenol, and the like. One of these cationic polymers may be used alone, or two or more thereof may be used in combination. Among these, polyallylamine or a derivative thereof is preferable.

Examples of the polymer having a carboxylic acid that forms an ionic polymer complex with polyethyleneimine include polycarboxylic acid (salt) such as polyacrylic acid or an ionic salt thereof, or a copolymer obtained by introducing a comonomer into the polymer, or carboxymethyl cellulose or Examples thereof include polysaccharides having a carboxyl group such as ionic salts thereof.
As polyallylamine, it is possible to use homopolymers or copolymers of allylamine, allylamine amide sulfate, diallylamine, dimethylallylamine and the like. These amines may be free amines or amines stabilized with acetic acid or hydrochloric acid. It is also possible to use maleic acid, sulfur dioxide or the like as a copolymer component. Further, it is also possible to use a type in which a primary amine is partially methoxylated to impart thermal crosslinking properties.
In the case of aminophenol, it is also possible to use a type in which a primary amine is partially methoxylated to impart thermal crosslinking properties.

It is preferable that the cationic polymer forms a crosslinked structure in the corrosion prevention treatment layer 14. If the cationic polymer forms a crosslinked structure, the water resistance of the exterior material 10 is improved.
In order to form the crosslinked structure of the cationic polymer, a crosslinker may be used together with the cationic polymer when forming the corrosion prevention treatment layer 14. As a crosslinking agent for forming a cationic polymer into a crosslinked structure, for example, at least one selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, a compound having an oxazoline group, and a compound having a carbodiimide group The compound of.

Examples of the polyfunctional isocyanate compound include diisocyanates exemplified above in the description of the first adhesive layer 12; adducts obtained by reacting these diisocyanates with a polyhydric alcohol such as trimethylolpropane; and reaction of diisocyanates with water. Polyisocyanates such as burettes and trimers, isocyanurates, etc. obtained by the above-mentioned method; and blocked polyisocyanates obtained by blocking these polyisocyanates with alcohols, lactams, oximes and the like. .
Examples of the glycidyl compound include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and the like. Epoxy compounds obtained by reacting glycols with epichlorohydrin; epoxy compounds obtained by reacting epichlorohydrin with polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, and sorbitol; terephthalic acid phthalate, oxalic acid, and adipic acid And epoxy compounds obtained by reacting a dicarboxylic acid with epichlorohydrin.
Examples of the compound having a carboxy group include various aliphatic or aromatic dicarboxylic acids, and further, poly (meth) acrylic acid or an alkali (earth) metal salt of poly (meth) acrylic acid may be used. .
As the compound having an oxazoline group, a low-molecular compound having two or more oxazoline units can be used. When a polymerizable monomer such as isopropenyloxazoline is used, it is copolymerized with an acrylic monomer, for example, (meth) acrylic acid, alkyl (meth) acrylate, hydroxyalkyl (meth) acrylate, or the like. Can be used.
Examples of the compound having a carbodiimide group include the carbodiimide compounds exemplified above in the description of the first adhesive layer.

It is appropriate to mix these crosslinking agents in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the cationic polymer. If the amount of the crosslinking agent is less than the lower limit, the crosslinking structure becomes insufficient. On the other hand, when the amount is more than the upper limit, the pot life of the coating liquid may be reduced.
In the case where the cationic polymer is a derivative of polyallylamine obtained by methoxycarbonylating a primary amine of polyallylamine, it has thermal crosslinkability, so that it is possible to use a compound in which a crosslinker is added without adding a crosslinker. Regarded as substantially equivalent.
The crosslinking agents may be used alone or in combination of two or more.

Further, a silane coupling agent capable of selectively reacting an amine with a functional group and making a crosslinking point a siloxane bond may or may not be used in combination with a crosslinking agent. However, as described above, when there is a possibility that a component contained in the corrosion prevention treatment layer and the silane coupling agent may cause a side reaction and adversely affect the intended reaction, the corrosion prevention treatment layer 14 may be used as the silane coupling agent. It is preferable not to include a ring agent.
Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane , Vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, and γ-isocyanatopropyltriethoxysilane. In particular, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-isocyanatopropyltriethoxysilane are preferred in consideration of the reactivity with the cationic polymer or its copolymer. It is.

The anionic polymer is a compound that improves the stability of the corrosion prevention treatment layer 14.
Generally, it is not limited to the use of the exterior material. For example, in a protective layer provided for the purpose of preventing corrosion of aluminum foil by a corrosive compound, ion contamination, particularly alkali metal ions such as sodium ions and alkaline earth metal ions. Is contained, the protective layer may be eroded starting from the ion contamination.
If the corrosion prevention treatment layer 14 contains an anionic polymer, ion contamination can be fixed, and the resistance of the exterior material can be improved.

Anionic polymers are materials that have the exact opposite characteristics as the cationic polymers described above. Specific examples include a polymer having a carboxy group. Examples of the polymer include poly (meth) acrylic acid or a salt thereof, or a copolymer obtained by copolymerizing a monomer mixture containing (meth) acrylic acid or a salt thereof. Is mentioned.
Components other than (meth) acrylic acid or a salt thereof included in the monomer mixture include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, and t-butyl groups. An alkyl (meth) acrylate monomer having an alkyl group such as a butyl group, a 2-ethylhexyl group, or a cyclohexyl group; (meth) acrylamide, N-alkyl (meth) acrylamide or N, N-dialkyl (meth) acrylamide (as an alkyl group) Is methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, 2-ethylhexyl, cyclohexyl, etc.), N-alkoxy (meth) acrylamide And N, N-dialkoxy (meth) acrylamide, wherein the alkoxy group is a methoxy group, an ethoxy group, Group, isobutoxy group, etc.), amide group-containing monomers such as N-methylol (meth) acrylamide and N-phenyl (meth) acrylamide; and hydroxyl groups such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate Monomers; glycidyl group-containing monomers such as glycidyl (meth) acrylate and allyl glycidyl ether; silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane and (meth) acryloxypropyltriethoxysilane; (meth) acryloxypropyl isocyanate And the like in which an isocyanate group-containing monomer such as is copolymerized.

It is preferable that the anionic polymer also forms a crosslinked structure in the corrosion prevention treatment layer 14. When the anionic polymer forms a crosslinked structure, the water resistance of the exterior material 10 is improved.
In order to form the anionic polymer into a crosslinked structure, a crosslinker may be used together with the anionic polymer when forming the corrosion prevention treatment layer 14. Examples of the crosslinking agent for forming the anionic polymer into a crosslinked structure include the crosslinking agents exemplified above in the description of the cationic polymer. In addition to using the crosslinking agent described above, a method of forming a crosslinked structure such as ionic crosslinking using a titanium compound or a zirconium compound as a crosslinking agent may be used.
The crosslinking agent is suitably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the anionic polymer. If the amount of the crosslinking agent is less than the lower limit, the crosslinking structure becomes insufficient. On the other hand, when the amount is more than the upper limit, the pot life of the coating liquid may be reduced.
The crosslinking agents may be used alone or in combination of two or more. Further, a crosslinking agent and a silane coupling agent may be used in combination, or may not be used in combination. However, as described above, when there is a possibility that a component contained in the corrosion prevention treatment layer and the silane coupling agent may cause a side reaction and adversely affect the intended reaction, the corrosion prevention treatment layer 14 may be used as the silane coupling agent. It is preferable not to include a ring agent. When a crosslinking agent and a silane coupling agent are used in combination, examples of the silane coupling agent include the silane coupling agents exemplified above in the description of the cationic polymer.

As the corrosion prevention treatment, only one kind of corrosion prevention treatment may be performed, or two or more kinds of corrosion prevention treatments may be performed in combination. When a chemical conversion treatment is performed as the corrosion prevention treatment, the chemical conversion treatment may be performed using one compound alone, or may be performed using two or more compounds in combination.
When forming at least a part of the corrosion prevention treatment layer by any of the hot water conversion treatment, the anodic oxidation treatment, and the chemical conversion treatment among these corrosion prevention treatments, it is preferable to perform the above-described degreasing treatment in advance. In the case where a degreasing aluminum foil is used as the metal foil layer 13, it is not necessary to perform a degreasing treatment again in forming the corrosion prevention treatment layer 14.

Examples of the corrosion prevention treatment layer 14 include the following treatment layers (a) to (j).
(A) A multilayer in which a layer formed of a cationic polymer is laminated on a layer formed by the corrosion prevention treatment.
(B) A multilayer in which a layer formed of an anionic polymer is laminated on a layer formed by the corrosion prevention treatment.
(C) A multilayer in which a layer formed of a cationic polymer and an anionic polymer is laminated on a layer formed by the corrosion prevention treatment.
(D) A multilayer in which a layer formed of a cationic polymer and a layer formed of an anionic polymer are sequentially laminated on a layer formed by the corrosion prevention treatment.
(E) A multilayer in which a layer formed of an anionic polymer and a layer formed of a cationic polymer are sequentially laminated on a layer formed by the corrosion prevention treatment.
(F) A layer formed by a corrosion prevention treatment and containing a cationic polymer.
(G) A layer formed by a corrosion prevention treatment and containing an anionic polymer.
(H) A layer formed by a corrosion prevention treatment and containing a cationic polymer and an anionic polymer.
(I) A multilayer structure in which a layer formed of an anionic polymer is laminated on the layer of (f).
(J) A multilayer in which a layer formed of a cationic polymer is laminated on the layer of (g).

In the treatment layers (a) to (c), the layer formed by the corrosion prevention treatment is a layer in contact with the metal foil layer 13, and the layer formed of the cationic polymer and / or the anionic polymer is the second adhesive layer 15 This layer is in contact with.
In the treatment layer (d), the layer formed by the corrosion prevention treatment is a layer in contact with the metal foil layer 13, and the layer formed of an anionic polymer is a layer in contact with the second adhesive layer 15.
In the treatment layer (e), the layer formed by the corrosion prevention treatment is a layer in contact with the metal foil layer 13, and the layer formed of the cationic polymer is a layer in contact with the second adhesive layer 15.
In the treatment layers (f) to (h), the layer formed by the corrosion prevention treatment and containing the cationic polymer and / or the anionic polymer is a layer in contact with both the metal foil layer 13 and the second adhesive layer 15. is there.
In the treatment layer (i), the layer (f) is a layer in contact with the metal foil layer 13, and a layer formed of an anionic polymer is a layer in contact with the second adhesive layer 15.
In the treatment layer (j), the layer (g) is a layer in contact with the metal foil layer 13, and the layer formed of the cationic polymer is a layer in contact with the second adhesive layer 15.

The treatment layers (a) to (c) are formed, for example, as follows.
First, the surface of the metal foil layer 13 (the surface opposite to the first adhesive layer 12 side, hereinafter, this surface is also referred to as the “surface to be treated”) is subjected to degreasing, hot water denaturation, and anodic oxidation. At least one treatment selected from the group consisting of a treatment and a chemical conversion treatment is performed to obtain a layer formed by the corrosion prevention treatment. However, when the surface to be treated of the metal foil layer 13 is treated by a coating-type chemical conversion treatment, a coating agent containing neither a cationic polymer nor an anionic polymer is used.
Next, on the layer formed by the corrosion prevention treatment, at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer and, if necessary, a crosslinking agent or the like for forming the polymer into a crosslinked structure. The resulting material is applied, dried, cured and baked to obtain a layer formed of a cationic polymer and / or an anionic polymer.
As a coating method, a known method is used, and examples thereof include a gravure coater, a gravure reverse coater, a roll coater, a reverse roll coater, a die coater, a bar coater, a kiss coater, and a comma coater.

The processing layer (d) is formed, for example, as follows.
First, the surface to be treated of the metal foil layer 13 is treated in the same manner as in the treatment layers (a) to (c) to obtain a layer formed by the corrosion prevention treatment.
Next, a material containing a cationic polymer and, if necessary, a cross-linking agent for forming a cross-linked structure of the cationic polymer is applied onto the layer formed by the corrosion prevention treatment, and dried, cured, and baked. To obtain a layer formed of a cationic polymer.
Next, on the layer formed of the cationic polymer, a material containing an anionic polymer and, if necessary, a cross-linking agent for forming a cross-linked structure of the anionic polymer is applied, and dried, cured, and baked. To obtain a layer formed of an anionic polymer.
The treatment layer (e) is formed by replacing the formation order of the layer formed of the cationic polymer and the layer formed of the anionic polymer in the step of forming the treatment layer (d).

The processing layers (f) to (h) are formed, for example, as follows.
A coating agent containing trivalent chromium, at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer, and, if necessary, a crosslinking agent or the like for forming the polymer into a crosslinked structure is formed on the metal foil layer 13. Is applied, dried, cured and baked to obtain a layer formed by a corrosion prevention treatment and containing a cationic polymer and / or an anionic polymer.

The processing layer (i) is formed, for example, as follows.
On the layer (f), a material containing an anionic polymer and, if necessary, a cross-linking agent for forming the anionic polymer into a cross-linked structure is applied, dried, cured, and baked to obtain an anionic polymer. Is obtained.

The processing layer (j) is formed, for example, as follows.
On the layer (g), a material containing a cationic polymer and, if necessary, a crosslinking agent for forming the cationic polymer into a crosslinked structure is applied, and dried, cured, and baked. Is obtained.

  Among the above-described corrosion prevention treatments, degreasing treatment, hot water conversion treatment, anodic oxidation treatment, immersion type chemical conversion treatment, particularly hot water conversion treatment, anodic oxidation treatment, immersion type chemical conversion treatment, the metal foil layer by the treatment agent 13 dissolves the surface to be treated and forms a compound having excellent corrosion resistance (for example, when the metal foil layer 13 is an aluminum foil layer, an aluminum compound such as boehmite or alumite). The co-continuous structure is formed up to the layer formed by the prevention treatment.

Mass per unit area of the corrosion prevention treatment layer 14 is preferably 0.005~2.000g / ^{m 2,} and more preferably 0.010~0.100g / ^{m 2.} When the mass is equal to or more than the lower limit, the effect of suppressing the erosion of the metal foil layer 13 by the electrolytic solution is easily obtained. Further, even if the mass exceeds the upper limit, the effect of suppressing the erosion of the metal foil layer 13 by the electrolytic solution hardly changes.
In the above description, the weight per unit area is described, but if the specific gravity is known, it is also possible to convert the thickness of the corrosion prevention treatment layer 14 therefrom.

"Second adhesive layer"
The second adhesive layer 15 is a layer for bonding the metal foil layer 13 on which the corrosion prevention treatment layer 14 is formed and the sealant layer 16.
The second adhesive layer 15 is a layer containing a compound (hereinafter, also referred to as a “reactive compound”) reactive with a polymer contained in a layer of the corrosion prevention treatment layer 14 that is in contact with the second adhesive layer. is there. For example, when the corrosion prevention treatment layer 14 is the treatment layers (a), (e), (f), and (j), the second adhesive layer 15 contains a compound reactive with the cationic polymer. When the corrosion prevention treatment layer 14 is the treatment layer (b), (d), (g) or (i), the second adhesive layer 15 contains a compound having a reactivity with an anionic polymer. When the corrosion prevention treatment layer 14 is the treatment layers (c) and (h), the second adhesive layer 15 is formed of at least a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. Including one. However, the second adhesive layer 15 does not necessarily need to include the two types of compounds, and may include a compound having reactivity with both the cationic polymer and the anionic polymer.
Further, the second adhesive layer 15 may further include an acid-modified polyolefin resin.
Here, “having reactivity” means forming a covalent bond with a cationic polymer or an anionic polymer.

Examples of the compound having reactivity with the cationic polymer include at least one compound selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, and a compound having an oxazoline group.
As these polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group, the isocyanate compounds, oxazoline compounds, and cationic polymers exemplified above in the description of the first adhesive layer have a crosslinked structure. Examples of the crosslinking agent include the above-mentioned polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group.
Among these, a polyfunctional isocyanate compound is preferred because it has high reactivity with the cationic polymer and easily forms a crosslinked structure.

Examples of the compound having reactivity with the anionic polymer include at least one compound selected from the group consisting of a glycidyl compound, a compound having an oxazoline group, and a carbodiimide compound.
The glycidyl compound, the compound having an oxazoline group, and the carbodiimide compound are exemplified as the oxazoline compound, the carbodiimide compound, and the cross-linking agent for forming the cationic polymer into a cross-linked structure as described above in the description of the first adhesive layer. Glycidyl compounds, compounds having an oxazoline group, and the like.
Among these, glycidyl compounds are preferred because of their high reactivity with anionic polymers.

When the second adhesive layer 15 contains an acid-modified polyolefin resin described later, the reactive compound may also have reactivity with an acidic group in the acid-modified polyolefin resin (that is, form a covalent bond with the acidic group). preferable. Thereby, the adhesiveness with the corrosion prevention treatment layer 14 is further improved. In addition, the acid-modified polyolefin resin has a crosslinked structure, and the solvent resistance of the exterior material 10 is further improved.
It is preferable that the content of the reactive compound is equal to 10-fold equivalent to the acidic group in the acid-modified polyolefin resin. When the amount is equal to or more than the equivalent amount, the reactive compound sufficiently reacts with the acidic group in the acid-modified polyolefin resin. On the other hand, when it exceeds 10 equivalents, the crosslinked structure with the acid-modified polyolefin resin becomes insufficient, and there is a concern that the above-mentioned physical properties such as solvent resistance may be deteriorated.

The acid-modified polyolefin resin is obtained by introducing an acidic group into the polyolefin resin. Examples of the acidic group include a carboxy group and a sulfonic acid group, and a carboxy group is particularly preferred.
Examples of the acid-modified polyolefin resin having a carboxy group introduced into the polyolefin resin include, for example, an unsaturated carboxylic acid or an acid anhydride thereof, or an ester of an unsaturated carboxylic acid or an acid anhydride thereof in the presence of a radical initiator. And an acid-modified polyolefin resin obtained by graft modification. Hereinafter, the unsaturated carboxylic acid or its anhydride and the ester of the unsaturated carboxylic acid or its anhydride may be referred to as a graft compound.

Examples of the polyolefin resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymer.
As unsaturated carboxylic acids, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid and the like Is mentioned.
Examples of the acid anhydrides of unsaturated carboxylic acids include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic anhydride. And the like.
As esters of unsaturated carboxylic acids or their acid anhydrides, methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconic acid, Examples include dimethyl tetrahydrophthalic anhydride and dimethyl bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylate.

The proportion of the graft compound in the acid-modified polyolefin resin is preferably from 0.2 to 100 parts by mass based on 100 parts by mass of the polyolefin resin.
The temperature condition of the graft reaction is preferably from 50 to 250C, more preferably from 60 to 200C.
Although the reaction time also depends on the production method, in the case of a melt grafting reaction using a twin-screw extruder, it is preferably within the residence time of the extruder. Specifically, 2 to 30 minutes are preferable, and 5 to 10 minutes are more preferable.
The graft reaction can be carried out under both normal pressure and pressure conditions.
Examples of the radical initiator include an organic peroxide. Examples of the organic peroxide include alkyl peroxide, aryl peroxide, acyl peroxide, ketone peroxide, peroxyketal, peroxycarbonate, peroxyester, hydroperoxide and the like. These organic peroxides can be appropriately selected depending on the temperature conditions and the reaction time. In the case of the melt grafting reaction using the twin screw extruder described above, alkyl peroxide, peroxy ketal, and peroxy ester are preferable, and di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butyl are preferable. Peroxy-hexyne-3, dicumyl peroxide is more preferred.

The second adhesive layer 15 may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.
Note that a general adhesive used to bond the metal foil layer and the sealant layer may include a silane coupling agent. This is because the addition of a silane coupling agent promotes adhesion and enhances adhesion strength. However, when an adhesive containing a silane coupling agent is used, depending on the type of the functional group contained in the silane coupling agent, components other than the silane coupling agent contained in the adhesive layer and the silane coupling agent may be secondary. This may cause a reaction and adversely affect the intended cross-linking reaction. Therefore, when there is a possibility that the reaction may be adversely affected, it is preferable that the adhesive used for bonding the metal foil layer and the sealant layer does not contain a silane coupling agent.
In the present invention, the second adhesive layer 15 may or may not include a silane coupling agent. However, according to the present invention, since the second adhesive layer 15 contains a reactive compound, it forms a covalent bond with the polymer contained in the layer of the corrosion prevention treatment layer 14 that is in contact with the second adhesive layer, and causes corrosion. The adhesion strength between the prevention treatment layer 14 and the second adhesive layer 15 is improved. Therefore, sufficient adhesive strength can be obtained in the second adhesive layer 15 without adding a silane coupling agent for the purpose of promoting adhesion. Therefore, when there is a possibility that the cross-linking reaction may be adversely affected, it is preferable that the second adhesive layer 15 does not contain a silane coupling agent.

  The thickness of the second adhesive layer 15 is preferably 3 to 50 μm, more preferably 10 to 40 μm. If the thickness of the second adhesive layer 15 is not less than the lower limit, excellent adhesiveness is easily obtained. If the thickness of the second adhesive layer 15 is equal to or less than the upper limit, the amount of moisture transmitted from the side end surface of the exterior material 10 is reduced.

"Sealant layer"
The sealant layer 16 is a layer that imparts sealing properties to the exterior material 10 by heat sealing.
Examples of the material forming the sealant layer 16 include a polyolefin resin and an acid-modified polyolefin resin. Examples of the polyolefin resin and the acid-modified polyolefin resin include those exemplified above in the description of the second adhesive layer 15.

The sealant layer 16 may be a single-layer film or a multilayer film in which a plurality of layers are laminated. Depending on the required function, for example, a multilayer film in which a resin such as an ethylene-cycloolefin copolymer or polymethylpentene is interposed may be used in terms of imparting moisture resistance.
Further, the sealant layer 16 may contain various additives such as a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, a light stabilizer, and a tackifier.
The thickness of the sealant layer 16 is preferably from 10 to 100 μm, more preferably from 20 to 50 μm.

"Production method of exterior material for lithium battery"
The exterior material 10 shown in FIG. 1 can be manufactured by, for example, a manufacturing method including the following steps (1) to (3).
(1) A step of forming a corrosion prevention treatment layer 14 on one surface of the metal foil layer 13.
(2) A step of bonding the base material layer 11 to the other surface of the metal foil layer 13 (the surface opposite to the side on which the corrosion prevention treatment layer 14 is formed) via the first adhesive layer 12.
(3) A step of attaching a sealant layer 16 via a second adhesive layer 15 to the side of the metal foil layer 13 where the corrosion prevention treatment layer 14 is formed.

Step (1):
The corrosion prevention treatment layer 14 can be formed by subjecting one surface of the metal foil layer 13 to the above-described corrosion prevention treatment or the like. As a specific formation method, the method exemplified earlier in the description of the formation method of the processing layers (a) to (j) can be given.
When an aluminum foil is used as the metal foil layer 13, as described above, an untreated aluminum foil may be used, or an aluminum foil subjected to a degreasing treatment by a wet type or a dry type may be used.

Step (2):
The method of bonding the base material layer 11 to the other surface of the metal foil layer 13 (the surface opposite to the side on which the corrosion prevention treatment layer 14 is formed) via the first adhesive layer 12 includes dry lamination, Known methods such as non-solvent lamination and wet lamination can be adopted. Among these, it is preferable to use a dry lamination technique.
As the adhesive for forming the first adhesive layer 12, the polyurethane adhesive described for the first adhesive layer 12 is preferable.
Dry coating weight of the adhesive, preferably ^{1~10g / m 2, 3~7g / m} 2 is more preferable.
After bonding the base material layer 11 to the other surface of the metal foil layer 13, an aging (curing) treatment may be performed at room temperature to 100 ° C. in order to promote adhesion.

Step (3):
As a method of attaching the sealant layer 16 to the corrosion prevention treatment layer 14 side of the metal foil layer 13 via the second adhesive layer 15, a wet process and a dry process are exemplified.
In the case of the wet process, first, a compound having a reactivity with a cationic polymer or an anionic polymer and, if necessary, a solvent-diluted product or dispersion of an adhesive containing an acid-modified polyolefin resin or the like are added to the corrosion prevention treatment layer 14. Apply on top. Then, after evaporating the solvent at a predetermined temperature (when the adhesive contains an acid-modified polyolefin resin, at a temperature equal to or higher than the melting point), after adhering the sealant layer 16 by a dry lamination method or the like, or after evaporating the solvent, Further, after heating at a temperature equal to or higher than the melting point of the polymer to melt and soften and baking, the sealant layer 16 is laminated by a heat treatment such as a thermal lamination method to obtain the exterior material 10.
Examples of the coating method include various coating methods exemplified above in the description of the method for forming the treatment layers (a) to (c).

In the case of the dry process, first, a compound having a reactivity with a cationic polymer or an anionic polymer and, if necessary, an adhesive containing an acid-modified polyolefin resin or the like are extruded onto the corrosion prevention treatment layer 14 by extrusion lamination or the like. Thus, a second adhesive layer 15 is formed. Next, the exterior material 10 is obtained by laminating the sealant layer 16 formed in advance by an inflation method or a casting method by sandwich extrusion lamination or the like.
In addition, an adhesive constituting the second adhesive layer 15 and a resin constituting the sealant layer 16 are co-extruded by an inflation method or a casting method to produce a multilayer film. It is also possible to laminate on top by thermal lamination.
Further, if necessary, a heat treatment can be performed for the purpose of improving the adhesion between the coating composition (b) and the adhesive, but in the present invention, the above-described layer constitution is formed. Thus, the exterior material 10 having excellent adhesion can be obtained even with a small amount of heat during extrusion lamination.
Examples of the heat treatment method include an aging treatment, a method of immersing in a hot roll, and a method of pressing with a hot roll. The temperature of the heat treatment is preferably 40 ° C. or higher in the case of the aging treatment, and 150 ° C. or higher in the case of the method of immersing in a hot roll or the method of pressing with a hot roll (however, when the adhesive contains an acid-modified polyolefin resin, Temperature above its melting point) is preferred.

"Effects"
The packaging material of the present embodiment described above has a base material layer, a first adhesive layer, a metal foil layer, a corrosion prevention treatment layer, a second adhesive layer, and a sealant layer in this order. It is composed of a laminated body. In the corrosion prevention treatment layer, at least a layer in contact with the second adhesive layer contains at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer. Further, the corrosion prevention treatment layer is formed by subjecting the metal foil layer to at least one kind of treatment selected from the group consisting of a degreasing treatment, a hydrothermal modification treatment, an anodic oxidation treatment, and a chemical conversion treatment. On the other hand, the second adhesive layer is a layer containing a compound (reactive compound) reactive with the polymer contained in the layer in contact with the second adhesive layer.

Usually, the corrosion prevention treatment layer and the adhesive form a hydrogen bonding adhesive interface.
However, if the exterior material of the present embodiment, when the second adhesive layer is laminated on the corrosion prevention treatment layer, the polymer contained in the layer in contact with the second adhesive layer of the corrosion prevention treatment layer, The reactive compound contained in the second adhesive layer reacts to form a covalent bond. Therefore, a covalent bonding interface is formed between the corrosion prevention treatment layer and the second adhesive layer. A laminate having a covalent bonding interface tends to have higher interlayer adhesion strength than a laminate having a hydrogen bonding adhesive interface.

As described above, since the electrolytic solution has a high permeability to the sealant layer, the electrolytic solution and hydrofluoric acid generated by hydrolysis of the lithium salt as an electrolyte are present between the corrosion prevention treatment layer and the adhesive layer. Penetrate.
However, in the case of the exterior material of the present embodiment, a covalent bonding interface is formed between the corrosion prevention treatment layer and the second adhesive layer. A decrease in lamination strength can be suppressed. Therefore, the exterior material of the present invention is excellent in electrolytic solution resistance.
Moreover, in the case of the exterior material of the present embodiment, since the corrosion prevention treatment layer and the second adhesive layer are firmly adhered to each other by the formation of the covalent bonding interface, high lamination strength is exhibited even with a short aging time. .

  The corrosion prevention treatment layer is formed by subjecting the metal foil layer to at least one kind of treatment selected from the group consisting of a degreasing treatment, a hydrothermal alteration treatment, an anodic oxidation treatment, and a chemical conversion treatment. The layer formed by these corrosion prevention treatments plays a role of suppressing corrosion of the metal foil layer by hydrofluoric acid generated by a reaction between the electrolytic solution and moisture. In addition, by improving the interaction with the metal foil layer, it also plays a role in improving the adhesion with the second adhesive layer.

In general, a lithium battery is manufactured by molding an exterior material into a pocket shape by, for example, cold molding, and sealing the cell with a cell or an electrolytic solution serving as a battery body in the pocket. If the adhesion strength between the corrosion prevention treatment layer and the second adhesive layer is insufficient, stress is concentrated on the interface between the corrosion prevention treatment layer and the second adhesive layer during cold forming, and the Floating may occur. When a minute floating occurs, the electrolyte solution easily permeates and the insulating property is apt to be reduced.
However, in the case of the exterior material of the present embodiment, a covalent bonding interface is formed between the second corrosion prevention treatment layer and the second adhesive layer. Fine floating is unlikely to occur at the interface between the prevention treatment layer and the second adhesive layer, and a good adhesive interface can be formed, so that insulation can be ensured.

"Other embodiments"
The exterior material of the present invention is not limited to those described above. Although the exterior material 10 shown in FIG. 1 has the corrosion prevention treatment layer 14 provided only on one surface (the surface on the second adhesive layer 15 side) of the metal foil layer 13, the other surface (the other surface) of the metal foil layer 13 ( A corrosion prevention treatment layer may also be provided on the first adhesive layer 12 side).

  While preferred embodiments of the present invention have been described and described above, it should be understood that they are illustrative of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other changes can be made without departing from the scope of the invention. Therefore, the present invention should not be regarded as limited by the foregoing description, but rather by the appended claims.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples. Examples 2 to 4 are reference examples.
The materials used in each of the following examples are as follows.

"Material used"
<Corrosion prevention treatment layer>
A-1: A layer formed by subjecting one surface of the metal foil layer to an immersion type (but not including a resin binder) chromate treatment using a chromium compound.
B-1: A mixture of 90 parts by mass of polyallylamine and 10 parts by mass of a glycidyl compound, which was adjusted to a solid content concentration of 5% by mass using distilled water as a solvent.
B-2: Compound having 90 parts by mass of polyacrylic acid and an oxazoline group (copolymer of isopropenyl oxazoline and acrylic acid) adjusted to a solid content concentration of 5% by mass using distilled water as a solvent A mixture consisting of 10 parts by mass.

<Second adhesive layer>
C-1: An adhesive composition comprising 10 parts by mass (solid content ratio) of a polyisocyanate compound having an isocyanurate structure with respect to 100 parts by mass of a maleic anhydride-modified polyolefin resin dissolved in toluene. The blending amount of the polyisocyanate compound is three times the equivalent of the acidic group (carboxy group) of the maleic anhydride-modified polyolefin resin.
C-2: An adhesive composition in which a glycidyl compound is blended at 10 parts by mass (solid content ratio) with respect to 100 parts by mass of the maleic anhydride-modified polyolefin resin dissolved in toluene. The amount of the glycidyl compound is 5 times the equivalent of the acidic group (carboxy group) of the maleic anhydride-modified polyolefin resin.
C-3: An adhesive composition in which a polyester polyol composed of a hydrogenated dimer fatty acid and a diol and a polyisocyanate are blended so that the molar ratio (NCO / OH) becomes 2.

"Example 1"
First, one side of a metal foil layer made of aluminum foil was subjected to chromate treatment to form A-1, and then B-1 was coated on A-1 and dried to form a corrosion prevention treatment layer. . The coating of B-1 was performed by microgravure coating. The coating amount of B-1 was made to be 70~100mg / ^{m 2.}
Then, a polyurethane adhesive (A525 / A52, manufactured by Mitsui Chemicals Polyurethanes, Inc.) was dry-laminated on the other surface of the metal foil layer (the surface opposite to the side on which the corrosion prevention treatment layer was formed) by dry lamination. Coating was performed at a coating amount of 4 to 5 mg / m ² to form a first adhesive layer. A substrate layer made of a polyamide film was bonded via the first adhesive layer.
Next, C-1 was applied on the corrosion prevention treatment layer by dry lamination at a dry coating amount of 4 to 5 g / m ² to form a second adhesive layer. A polypropylene film having a thickness of 40 μm was laminated as a sealant layer via the second adhesive layer, and as shown in FIG. 1, a substrate layer 11 / first adhesive layer 12 / metal foil layer 13 / corrosion A laminate having a layer configuration of the prevention treatment layer 14 / the second adhesive layer 15 / the sealant layer 16 was obtained.
The obtained laminate was aged at 40 ° C. for 5 days or 10 days to obtain an exterior material.

<Evaluation>
(Evaluation of electrolyte resistance)
Each of the obtained exterior materials was cut into a strip having a size of 100 × 15 mm and used as a sample for evaluation, and the following electrolytic solution resistance was evaluated. Table 1 shows the results.
An electrolyte was prepared by adding LiPF ₆ to a solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to have a concentration of 1 M, and filled in a Teflon (registered trademark) container. . The sample was put in it, and after sealing, it was stored at 85 ° C. for 4 hours. Thereafter, the sample was taken out of the container and further immersed in water for 2 hours. The peeling state of the sample after immersion was evaluated according to the following criteria. In addition, when the evaluation of the electrolyte property of the exterior material obtained by aging for 5 days is “O” or “◎”, it is judged as acceptable.
A: Lamination strength is 10 N / 15 mm or more (crosshead speed is 300 mm / min).
：: Lamination strength is 5 N / 15 mm or more and less than 10 N / 15 mm (crosshead speed is 300 mm / min).
Δ: Lamination strength is less than 5 N / 15 mm (crosshead speed is 300 mm / min).
X: Delamination occurs and the lamination strength cannot be measured.

(Evaluation of insulation)
Each of the obtained exterior materials was molded into a pocket having a size of 70 × 80 mm and a depth of 4 mm using a cold molding machine. Inside the obtained molded product, 5 g of the electrolytic solution prepared as the content in the evaluation of the electrolytic solution resistance was accommodated, and the product was covered with a non-molded exterior material. At this time, a molded product and an unmolded exterior material were overlapped so that the sealant layer faced, and sealed by heat sealing to obtain a molded sample. Also, at the time of heat sealing, the aluminum tab lead (Al tab lead) is immersed in an electrolytic solution together with a tab film made of an acid-modified polyolefin film, and one end is immersed in an electrolytic solution and the other end is out of the molded sample. Sealing was performed by interposing between the outer material that was not performed.
A part of the surface (outer layer portion) of the obtained molded sample is sanded to intentionally expose a metal foil layer made of aluminum foil, and then electrode terminals are attached to the exposed metal foil layer and the Al tab lead. The insulation resistance value when applied at an applied voltage of 25 V was measured and evaluated according to the following criteria.
：: Insulation resistance value is 100 MΩ or more (measurement limit is 200 MΩ).
Δ: Insulation resistance value is 50 MΩ or more and less than 100 MΩ.
×: Insulation resistance value is less than 50 MΩ.

"Examples 2 to 4, Comparative Examples 1 to 4"
An exterior material was produced and evaluated in the same manner as in Example 1, except that the materials used for forming the corrosion prevention treatment layer and the second adhesive layer were changed as shown in Table 1. Table 1 shows the results.

As is clear from Table 1, the exterior materials obtained in the respective examples were excellent in electrolytic solution resistance and insulation.
On the other hand, the exterior materials obtained in Comparative Examples 1 to 3 in which the corrosion prevention treatment layer did not contain a cationic polymer or an anionic polymer were delaminated and inferior in electrolyte resistance. In addition, since the delamination occurred in the exterior materials obtained in Comparative Examples 1 to 3, the insulation properties were not evaluated.
The exterior material obtained in Comparative Example 4 in which the corrosion prevention treatment layer contains an anionic polymer and the second adhesive layer contains a compound having reactivity with a cationic polymer has sufficient lamination strength when the aging days are short. It was not obtained and was poor in electrolysis resistance. Further, the exterior material obtained in Comparative Example 4 showed an insulation resistance value usable as a consumer battery, but was inferior in insulation to the exterior material obtained in each Example.

  ADVANTAGE OF THE INVENTION According to this invention, the exterior | packing material for lithium batteries which expresses high lamination strength even by short aging time, is excellent in electrolyte solution resistance, and can ensure insulation even if it performs cold molding is obtained.

DESCRIPTION OF SYMBOLS 10 Exterior material for lithium batteries 11 Base layer 12 First adhesive layer 13 Metal foil layer 14 Corrosion prevention treatment layer 15 Second adhesive layer 16 Sealant layer

Claims (5)

A base layer, a first adhesive layer, a metal foil layer, a single-layer or multi-layer corrosion prevention treatment layer, a second adhesive layer, and a sealant layer laminated in this order. Composed of the body,
Corrosion treatment layer provided on at least a second adhesive layer side, at least a second layer in contact with the adhesive layer comprises a cationic polymer over, and corrosion prevention treatment layer degreasing process to the metal foil layer, the heat Water conversion treatment, anodizing treatment, formed by performing at least one treatment selected from the group consisting of a chemical conversion treatment,
The second adhesive layer includes a compound having reactivity with the cationic polymer contained in the layer in contact with the second adhesive layer, and an acid-modified polyolefin resin, and does not include a silane coupling agent .
The cationic polymer is a polymer containing an amine,
An exterior material for a lithium battery, wherein the compound having reactivity with the cationic polymer is a polyfunctional isocyanate compound . Cationic polymer is polyethyleneimine, ionic polymer complex composed of polyethyleneimine and polymer having carboxylic acid, primary amine-grafted acrylic resin having primary amine grafted on acrylic main skeleton, polyallylamine or derivative thereof, aminophenol The exterior material for a lithium battery according to claim 1 , wherein the exterior material is at least one selected from the group consisting of: The corrosion prevention treatment layer further includes an anionic polymer in a layer in contact with the second adhesive layer,
The second adhesive layer further includes a compound reactive with the anionic polymer, and the compound reactive with the anionic polymer is selected from the group consisting of a glycidyl compound, a compound having an oxazoline group, and a carbodiimide compound. at least a kind, exterior material for a lithium battery according to claim 1 or 2 which is. The anionic polymer is a polymer having a carboxy group, and the polymer is a copolymer obtained by copolymerizing a monomer mixture containing poly (meth) acrylic acid or a salt thereof, or (meth) acrylic acid or a salt thereof; The exterior material for a lithium battery according to claim 3 . The exterior for a lithium battery according to any one of claims 1 to 4 , wherein a corrosion prevention treatment layer having a single-layer configuration or a multilayer configuration is provided between the first adhesive layer and the metal foil layer. Wood.

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