JP2015144122A - Sheath material for lithium batteries - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheath material for lithium batteries which develops a high lamination strength even with a short aging time, has superior resistance against electrolyte, and arranged so that an insulating property to be ensured even when the cold molding of the material is performed.SOLUTION: A sheath material 10 for lithium batteries comprises: a laminate including a base material layer 11, a first adhesive layer 12, a metal foil layer 13, a mono-layered or multilayered anticorrosion-processed layer 14, a second adhesive layer 15, and a sealant layer 16 which are laminated in this order. The anticorrosion-processed layer 14 is provided at least on the side of the second adhesive layer, and includes at least one kind of polymer selected from a group consisting of cationic polymer and anionic polymer in at least a layer adjoining the second adhesive layer 15. The anticorrosion-processed layer 14 is formed by performing, on the metal foil layer 13, at least one kind of processing selected from a group consisting of a degreasing treatment, a hot water modifying treatment, an anode oxidation treatment and a chemical conversion treatment. The second adhesive layer 15 includes a compound reactive with the polymer included in the layer adjoining the second adhesive layer 15.

Description

  The present invention relates to a packaging material for a lithium battery.

As a secondary battery for consumer use used in portable terminal devices such as personal computers and mobile phones, and video cameras, lithium-ion batteries that are ultra-thin and miniaturized while being high energy have been actively developed.
As an exterior material for a lithium ion battery (hereinafter, sometimes simply referred to as an “exterior material”), it is a multilayer structure because it is lightweight and can freely select a battery shape instead of a conventional metal can. Laminate film is used. Moreover, the exterior material using such a laminate film is not only flexible in the shape of the battery, but also lightweight, high heat dissipation, and low cost. Application to electric vehicle batteries is also being attempted.

  The laminate film has a structure in which a sealant layer (heat-fusible film) is laminated on one surface of a metal foil layer such as an aluminum foil via an adhesive layer, and the other surface is interposed via an adhesive layer. A configuration (base material layer / adhesive layer / metal foil layer / adhesive layer / sealant layer) in which a material layer (plastic film) is laminated is common.

A lithium ion battery using a laminate film type exterior material is, for example, a positive electrode material, a negative electrode material, and a separator as a battery body part in a molded product obtained by deep drawing the above-described laminate film by cold molding (deep drawing molding). At the same time, an electrolyte layer made of an electrolytic solution or a polymer gel impregnated with the electrolytic solution is accommodated and heat sealed by heat sealing.
As the electrolytic solution, an electrolytic solution in which a lithium salt is dissolved in an aprotic solvent (propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or the like) is used.
The electrolytic solution is highly permeable to the sealant layer. Therefore, in the lithium ion battery, the electrolyte solution that has penetrated into the sealant layer may reduce the laminate strength between the metal foil layer and the sealant layer, and the electrolyte solution may eventually leak out. In addition, lithium salts such as LiPF ₆ and LiBF ₄ that are electrolytes may generate hydrofluoric acid by a hydrolysis reaction. Hydrofluoric acid causes corrosion of the metal surface and a decrease in 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 a demand, for example, Patent Document 1 discloses a carboxy compound as a packaging material that suppresses a temporal decrease in the laminate strength between the sealant layer and the metal foil layer due to the electrolytic solution and has sufficient electrolytic solution resistance. An exterior material in which a sealant layer and a metal foil layer are bonded via a layer (adhesive layer) made of an adhesive containing a polyolefin resin having a group and a polyfunctional isocyanate compound is disclosed.

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 slow reaction rate. When the reaction rate was slow, it was 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 Document 1 forms a cross-linked structure, it can function as an insulating layer such as a seal with an electrode tab or a degassing seal process during battery manufacture. .
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 is the interface between the sealant layer and the metal foil layer. Concentration on the surface sometimes caused fine floating. As a result, the insulating property may be lowered based on the fine float.

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

  The present invention has been made in view of the above circumstances, and exhibits an excellent laminate strength even in a short aging time, has excellent electrolytic solution resistance, and can ensure insulation even when cold-molded. 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 corrosion prevention treatment layer having a single layer structure or a multilayer structure, a second adhesive layer, and a sealant layer in this order. Consists of laminated laminates, the corrosion prevention treatment layer is provided at least on the second adhesive layer side, and at least a layer in contact with the second adhesive layer is selected from the group consisting of a cationic polymer and an anionic polymer The corrosion prevention treatment layer containing one kind of polymer is formed by subjecting the metal foil layer to at least one treatment selected from the group consisting of a degreasing treatment, a hydrothermal alteration treatment, an anodizing treatment, and a chemical conversion treatment, A 2nd adhesive bond layer is an exterior material for lithium batteries containing the compound reactive with the said polymer contained in the layer which contact | connects said 2nd adhesive bond layer.
[2] The corrosion prevention treatment layer includes 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], which is at least one selected from the group consisting of a glycidyl compound, a compound having a carboxy group, and a compound 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 in which a primary amine is grafted to an acrylic main skeleton, polyallylamine or a derivative thereof The exterior material for a lithium battery according to [2], which is at least one selected from the group consisting of aminophenols.
[4] The anticorrosion treatment layer contains an anionic polymer in a layer in contact with the second adhesive layer, and the compound having reactivity with the anionic polymer contained in the second adhesive layer is a glycidyl compound or oxazoline. The external packaging material for lithium batteries according to [1], which is at least one selected from the group consisting of a group-containing compound and a carbodiimide compound.
[5] A copolymer in which the anionic polymer is a polymer having a carboxy group, and the polymer is copolymerized with poly (meth) acrylic acid or a salt thereof, or a monomer mixture containing (meth) acrylic acid or a salt thereof. The packaging material for a lithium battery according to [4].
[6] The packaging 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 corrosion prevention treatment layer having a single layer structure or a multilayer structure is provided between the first adhesive layer and the metal foil layer, according to any one of [1] to [6]. For lithium batteries.

  The outer packaging material for a lithium battery of the present invention exhibits a high laminate strength even with a short aging time, is excellent in electrolytic solution resistance, and can ensure insulation even when cold forming is performed.

It is sectional drawing which shows an example of the exterior material for lithium batteries of this invention.

Hereinafter, a lithium battery exterior material (hereinafter simply referred to as “exterior material”) 10 shown in FIG. 1 will be described as an example of the lithium battery exterior material of the present invention. In each drawing used for the following description, the scale of each member is appropriately changed 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 the sealant layer 16 are constituted by a laminate in which the layers are laminated in this order.
The packaging material 10 is used with 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 such as imparting heat resistance in a heat sealing process when manufacturing a lithium battery, and suppressing generation of pinholes that may occur during molding processing and distribution. In particular, in the case of an exterior material for a large-sized lithium battery, scratch resistance, chemical resistance, insulation, 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 stretched or unstretched films such as polyester film, polyamide film, and polypropylene film.
The base material layer 11 may be one layer or two or more layers. For example, the base material layer 11 may be a single layer resin layer composed of any one of the above resin films, or may be a multi-layer resin layer in which two or more of the above resin films are laminated. Good. Examples of these resin layers include stretched or unstretched polyamide films, stretched or unstretched polyester films, and two-layer films of stretched polyamide films and stretched polyester films. Further, for example, a coextruded multilayer biaxially stretched multilayer film obtained by coextrusion of polyester and polyamide using an adhesive resin and then biaxial stretching may be used as the base material layer 11.

  The base material layer 11 is preferably a stretched polyamide film in terms of excellent moldability and heat resistance. Moreover, as the base material layer 11, a stretched polyester film is preferable in terms of excellent acid resistance. Moreover, as the base material layer 11, a laminated film of a stretched polyamide film and a stretched polyester film is preferable from the viewpoint of easily achieving moldability, heat resistance, and acid resistance.

The thickness of the base material layer 11 is preferably 6 μm or more and more preferably 10 μm or more in terms of moldability, heat resistance, pinhole resistance, and insulation. Moreover, 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 total thickness.

On the outermost surface of the base material layer 11 (surface opposite to the first adhesive layer 12 side), acid resistance imparting agent, flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, 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. It is done.
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 anti-blocking agent, various filler-based anti-blocking agents such as silica are preferable.
These additives may be used alone or in combination of two or more.

"First adhesive layer"
The first adhesive layer 12 is a layer that bonds the base material layer 11 and the metal foil layer 13 together.
The 1st adhesive bond layer 12 can be formed using a well-known thing as an adhesive agent used for the lamination of a resin film and metal foil. Examples of the adhesive include a polyurethane-based adhesive containing a main agent composed of a polyol such as polyester polyol, polyether polyol, acrylic polyol, and carbonate polyol, and a curing agent composed of a bifunctional or higher functional isocyanate compound. A polyurethane-based resin is formed by allowing the curing agent to act on the main agent.

As the polyester polyol, one obtained by reacting at least one polybasic acid with at least one diol can be used.
Examples of the polybasic acid include aliphatic dibasic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and brassylic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc. And dibasic acids such as aromatic dibasic acids.
Examples of the diol include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol, and other aliphatic diols, cyclohexanediol, water, and the like. Examples thereof 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 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 (TDI) or a hydrogenated product thereof, crude TDI, xylylene diisocyanate (XDI) or a hydrogenated product thereof, hexamethylene diisocyanate (HDI), 4 , 4'-diphenylmethane diisocyanate (MDI) or its hydrogenated product, 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 diisocyanate Such as diisocyanate such as hexyl-4,4'-diisocyanate, and the like.
These isocyanate compounds may be used individually by 1 type, and may use 2 or more types together.

  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 (meth) Kurylamide (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, silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane, (meth) acryloxypropyltriethoxylane, and isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate What was polymerized is mentioned.

As the carbonate polyol, one obtained by reacting a carbonate compound and 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 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.

Examples of the bifunctional or higher functional isocyanate compound used as the curing agent include the isocyanate compounds exemplified above in the description of the polyester polyol.
1-100 mass parts is preferable with respect to 100 mass parts of main agents, and, as for the compounding quantity of a hardening | curing agent, 5-50 mass parts is more preferable. 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.

It is also possible to mix a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent, and the like with the polyurethane adhesive for promoting 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, N, N'-di-p-toluylcarbodiimide and the like. As the carbodiimide compound, 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 unit represented by the following general formula (3) Compound etc. are mentioned.

  In general formula (1)-(3), n is an integer of 2-30, respectively, Preferably it is an integer of 3-20.

  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, polyalkylene glycol, sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, trimethylolpropane and the like. Polyglycidyl ethers of aliphatic polyols, polyglycidyl ethers of alicyclic polyols such as cyclohexanedimethanol, aliphatic and aromatic such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid and sebacic acid Diglycidyl ester or polyglycidyl ester of polycarboxylic acid, resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p-hydroxyphenyl) propane, Diglycidyl ether or polyglycidyl ether of polyhydric phenols such as ris- (p-hydroxyphenyl) methane, 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane, N, N′-diglycidylaniline, N N, N-N-diglycidyl toluidine, N, N, N ′, N′-tetraglycidyl-bis- (p-aminophenyl) methane, etc., N-glycidyl derivatives, aminofail triglycidyl derivatives, triglycidyl tris (2-Hydroxyethyl) isocyanurate, triglycidyl isocyanurate, orthocresol type epoxy, phenol novolac type epoxy and the like.

  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-tert-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, and γ-glycid. Xylpropyltriethoxysilane, 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.

  1-10 micrometers is preferable and, as for the thickness of the 1st adhesive bond layer 12, 3-7 micrometers is more preferable. When it is 1 μm or more, the laminate strength as an adhesive is improved, and when it is 10 μm or less, when the exterior material 10 is made into a deep-drawn molded product by cold forming, electrolysis is also performed at the drawn corners of the deep-drawn molded product. The float between the base material layer 11 and the metal foil layer 13 under a liquid atmosphere can be sufficiently suppressed.

"Metal foil layer"
The metal foil layer 13 has a water vapor barrier property that prevents moisture from entering the battery. Moreover, the metal foil layer 13 has spreadability in order to perform deep drawing.
Various metal foils, such as aluminum and stainless steel, can be used as the metal foil layer 13, and aluminum foil is preferable from the viewpoint of weight (specific gravity), moisture resistance, workability, and cost. A metal foil layer made of an aluminum foil is also referred to as an “aluminum foil layer”.

As an aluminum foil used as 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 extensibility at the time of molding. The content of iron in the aluminum foil (100% by mass) is preferably 0.1 to 9.0% by mass and more preferably 0.5 to 2.0% by mass with respect to 100% by mass of the total mass of the aluminum foil. preferable. If the iron content is at least the lower limit, pinhole resistance and spreadability are improved. If the iron content is less than or equal to the upper limit, flexibility is improved.
The thickness of the aluminum foil layer is preferably 9 to 200 μm, more preferably 15 to 100 μm, from the viewpoint of barrier properties, pinhole resistance, and workability.

Although untreated aluminum foil may be used for the metal foil layer 13, it is preferable to use a degreased aluminum foil. 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. These acids may be used individually by 1 type, and may use 2 or more types together. Moreover, you may mix | blend various metal salts used as supply sources, such as an iron (III) ion and a cerium (III) ion, as the etching effect of aluminum foil improves. Examples of the alkali used for alkali degreasing include strong etching type alkali such as sodium hydroxide. Moreover, you may use what mix | blended weak alkali type and surfactant. 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, frame treatment, corona treatment, and the like can be given. Furthermore, a degreasing process in which contaminants are oxidatively decomposed / removed by active oxygen generated by irradiating ultraviolet rays having 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 the metal foil layer 13 from being corroded by an electrolytic solution or hydrofluoric acid.
The corrosion prevention treatment layer 14 includes at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer in a layer in contact with at least the second adhesive layer. 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 hydrothermal alteration treatment, an anodizing treatment, and a chemical conversion treatment.
In addition, when providing coating layers, such as the corrosion prevention process layer 14, on the metal foil layer 13, generally the technique which improves an interface adhesive force using a silane coupling agent may be 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 functional group contained in the silane coupling agent to be used, a component contained in the later-described corrosion prevention treatment layer and the silane coupling agent may cause a side reaction, which may adversely affect the intended reaction. is there. For this reason, when there is a risk of adverse effects on the reaction, the corrosion prevention treatment layer 14 preferably does not contain a silane coupling agent.
Hereinafter, degreasing treatment, hydrothermal alteration treatment, anodizing treatment, and chemical conversion treatment are collectively referred to as “corrosion prevention treatment”.

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. Further, as an acid degreasing, an acid degreasing agent in which a fluorine-containing compound such as monosodium ammonium difluoride is dissolved with the above inorganic acid is used, so that not only the degreasing effect of the metal foil layer 13 but also a metal fluoride that is passive. 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 a dipping type and a coating type.
Examples of the immersion type chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or various chemical conversion treatments composed of these mixed phases. It is done. The coating type is a method of forming by coating by further adding a resin component to the chemical conversion treatment agent used in these chemical conversion treatments. Among the chemical conversion treatments, chromate treatment is preferable because it has excellent corrosion resistance.

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

In general formulas (4) to (7), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group, respectively. R ¹ and R ² are the same or different and are a hydroxy group, an alkyl group, or a hydroxyalkyl group.
Examples of the alkyl group include straight chain or branched chains 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. An 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, and a 2-hydroxy group. Examples thereof include a linear or branched 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 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 units represented by the general formulas (4) to (7) is not particularly limited, but is preferably 500 to 1,000,000, more preferably 1000 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. Further, in the case of performing phosphoric acid chromate treatment, 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, more preferably. 1.0 to 40.0 mg. Moreover, if the chromate treatment using the aminated phenol polymer is performed, 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. Is more preferable, and 5.0 to 150.0 mg is more preferable.

  In addition, the coating agent used for a 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 that is excellent in resistance to electrolytic solution and hydrofluoric acid. The cause is presumed to be to suppress damage to the aluminum foil by trapping fluorine ions with a cationic group (anion catcher).
Examples of the cationic polymer include an amine-containing polymer. Specifically, polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, and a primary amine grafted on an acrylic main skeleton 1 Examples include secondary amine graft acrylic resins, polyallylamine or derivatives thereof, and aminophenols. These cationic polymers may be used alone or in combination of two or more. Among these, polyallylamine or a derivative thereof is preferable.

As a polymer having a carboxylic acid that forms an ionic polymer complex with polyethyleneimine, a polycarboxylic acid (salt) such as polyacrylic acid or an ionic salt thereof, a copolymer having a comonomer introduced therein, carboxymethylcellulose, The polysaccharide which has carboxyl groups, such as the ionic salt, is mentioned.
As the polyallylamine, homopolymers or copolymers such as allylamine, allylamine amide sulfate, diallylamine, and dimethylallylamine can be used. These amines may be free amines or amines stabilized with acetic acid or hydrochloric acid. Moreover, it is also possible to use maleic acid, sulfur dioxide, etc. as a copolymer component. Furthermore, it is also possible to use a type in which a primary amine is partially methoxylated to give thermal crosslinkability.
In addition, in the case of aminophenol, it is possible to use a type in which thermal crosslinkability is imparted by partially methoxylating a primary amine.

The cationic polymer preferably 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 make the cationic polymer into a crosslinked structure, a crosslinking agent may be used together with the cationic polymer when the corrosion prevention treatment layer 14 is formed. As a crosslinking agent for making 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 this is mentioned.

Examples of the polyfunctional isocyanate compound include the diisocyanates exemplified above in the description of the first adhesive layer 12; adducts obtained by reacting these diisocyanates with polyhydric alcohols such as trimethylolpropane, and the diisocyanates react with water. Polyisocyanates such as burettes and isocyanurates that are trimers; blocked polyisocyanates obtained by blocking these polyisocyanates with alcohols, lactams, oximes, etc. .
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 reacted with glycols and epichlorohydrin; epoxy compounds reacted with polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol and epichlorohydrin; terephthalic acid phthalate, oxalic acid, adipic acid And an epoxy compound obtained by reacting a dicarboxylic acid such as epichlorohydrin.
Examples of the compound having a carboxy group include various aliphatic or aromatic dicarboxylic acids, and 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 isopropenyl oxazoline is used, it is copolymerized with an acrylic monomer such as (meth) acrylic acid, (meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyalkyl, or the like. Things 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.

These crosslinking agents are suitably blended in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the cationic polymer. When the blending amount of the crosslinking agent is less than the lower limit value, the crosslinked structure becomes insufficient. On the other hand, if the blending amount is greater than the above upper limit value, the coating pot life may be reduced.
In addition, when the cationic polymer is a polyallylamine derivative obtained by methoxycarbonylating a primary amine of polyallylamine, since it has thermal crosslinkability, it is blended with a crosslinking agent without blending a crosslinking agent. Considered substantially equivalent.
A crosslinking agent may be used individually by 1 type, and may use 2 or more types together.

Furthermore, a silane coupling agent capable of selectively reacting an amine and a functional group to form a crosslinking point into a siloxane bond may or may not be used in combination with the crosslinking agent. However, as described above, when the component contained in the corrosion prevention treatment layer and the silane coupling agent cause a side reaction, which may cause an adverse effect on the original intended reaction, the corrosion prevention treatment layer 14 is a silane cup. It is preferable not to contain a ring agent.
Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and 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 preferable in consideration of reactivity with a cationic polymer or a copolymer thereof. It is.

The anionic polymer is a compound that improves the stability of the corrosion prevention treatment layer 14.
In general, not limited to the use of exterior materials, for example, in a protective layer provided for the purpose of preventing corrosion of an aluminum foil by a corrosive compound, ion contamination, especially alkali metal ions such as sodium ions and alkaline earth metal ions If this is included, the protective layer may be attacked starting from this 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.

An anionic polymer is a material that has the exact opposite properties of the cationic polymer described above. Specific examples include a polymer having a carboxy group, and the polymer is a copolymer obtained by copolymerizing poly (meth) acrylic acid or a salt thereof, or a monomer mixture containing (meth) acrylic acid or a salt thereof. Is mentioned.
Components other than (meth) acrylic acid or a salt thereof contained in the monomer mixture include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t- Alkyl (meth) acrylate monomers having alkyl groups such as butyl, 2-ethylhexyl and cyclohexyl; (meth) acrylamide, N-alkyl (meth) acrylamide and N, N-dialkyl (meth) acrylamide (as alkyl groups) Are 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 And N, N-dialkoxy (meth) acrylamide (the alkoxy groups include methoxy, ethoxy, butoxy Group, isobutoxy group, etc.), amide group-containing monomers such as N-methylol (meth) acrylamide and N-phenyl (meth) acrylamide; 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) acryloxypropyltriethoxylane; (meth) acryloxypropyl isocyanate And those obtained by copolymerizing an isocyanate group-containing monomer such as

It is preferable that the anionic polymer also forms a crosslinked structure in the corrosion prevention treatment layer 14. If the anionic polymer forms a crosslinked structure, the water resistance of the exterior material 10 is improved.
In order to make the anionic polymer into a crosslinked structure, a crosslinking agent may be used together with the anionic polymer when the corrosion prevention treatment layer 14 is formed. As a crosslinking agent for making an anionic polymer into a crosslinked structure, the crosslinking agent illustrated previously in description of a cationic polymer is mentioned. In addition to using the above-mentioned crosslinking agent, 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 blended in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the anionic polymer. When the blending amount of the crosslinking agent is less than the lower limit value, the crosslinked structure becomes insufficient. On the other hand, if the blending amount is greater than the above upper limit value, the coating pot life may be reduced.
A crosslinking agent may be used individually by 1 type, and may use 2 or more types together. Moreover, you may use together a crosslinking agent and a silane coupling agent, and it is not necessary to use together. However, as described above, when the component contained in the corrosion prevention treatment layer and the silane coupling agent cause a side reaction, which may cause an adverse effect on the original intended reaction, the corrosion prevention treatment layer 14 is a silane cup. It is preferable not to contain a ring agent. When the crosslinking agent and the 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.

Corrosion prevention treatment may be performed with only one type of corrosion prevention treatment or with two or more types of corrosion prevention treatments. Further, when the chemical conversion treatment is performed as the corrosion prevention treatment, the chemical conversion treatment may be performed using one kind of compound alone, or may be performed using two or more kinds of compounds in combination.
Of these corrosion prevention treatments, when at least a part of the corrosion prevention treatment layer is formed by any one of hydrothermal alteration treatment, anodization treatment, and chemical conversion treatment, it is preferable to perform the degreasing treatment described above in advance. When using a degreased aluminum foil as the metal foil layer 13, it is not necessary to degrease again in the formation of 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 a corrosion prevention treatment.
(B) A multilayer in which a layer formed of an anionic polymer is laminated on a layer formed by a 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 a 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 a 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 a 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 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 by the cationic polymer and / or the anionic polymer is the second adhesive layer 15. It is a layer 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 by 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 by 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 treated layer (i), the layer (f) is in contact with the metal foil layer 13, and the layer formed of an anionic polymer is in contact with the second adhesive layer 15.
In the treated 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 as follows, for example.
First, the surface of the metal foil layer 13 (the surface opposite to the first adhesive layer 12 side, hereinafter referred to as “surface to be treated”) is degreased, hydrothermally modified, and anodized. At least one treatment selected from the group consisting of treatment and chemical conversion treatment is performed to obtain a layer formed by the corrosion prevention treatment. However, when processing the to-be-processed surface of the metal foil layer 13 by an application | coating type chemical conversion treatment, what does not contain a cationic polymer and an anionic polymer is used as a coating agent.
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 a cross-linking agent for making the polymer a cross-linked structure, if necessary, are provided. The containing 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 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 treatment layer (d) is formed as follows, for example.
First, the treated surface of the metal foil layer 13 is treated in the same manner as the treated layers (a) to (c) to obtain a layer formed by the corrosion prevention treatment.
Next, on the layer formed by this corrosion prevention treatment, a material containing a cationic polymer and, if necessary, a crosslinking agent for making the cationic polymer into a crosslinked structure, is coated, dried, cured and baked. To obtain a layer formed of a cationic polymer.
Next, on the layer formed with the cationic polymer, a material containing an anionic polymer and, if necessary, a cross-linking agent for making the anionic polymer into a cross-linked structure is coated, dried, cured, and baked. To obtain a layer formed of an anionic polymer.
The treatment layer (e) is formed by changing the formation order of the layer formed of the cationic polymer and the layer formed of the anionic polymer in the formation step of the treatment layer (d).

The treatment layers (f) to (h) are formed as follows, for example.
Metal foil layer 13 includes 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 for making the polymer into a crosslinked structure. The surface to be treated is coated, dried, cured, and baked to form a layer containing a cationic polymer and / or an anionic polymer formed by a corrosion prevention treatment.

The treatment layer (i) is formed as follows, for example.
On the layer (f), an anionic polymer and, if necessary, a material containing a crosslinking agent for making the anionic polymer into a crosslinked structure are coated, dried, cured and baked, and then the anionic polymer. The layer formed in is obtained.

The treatment layer (j) is formed as follows, for example.
On the layer (g), a cationic polymer and, if necessary, a material containing a crosslinking agent for making the cationic polymer into a crosslinked structure are coated, dried, cured, and baked, and then the cationic polymer. The layer formed in is obtained.

  Of the above-described corrosion prevention treatments, degreasing treatment, hydrothermal alteration treatment, anodizing treatment, immersion type chemical treatment, particularly hydrothermal transformation treatment, anodizing treatment, and immersion type chemical treatment are carried out with a metal foil layer depending on the treatment agent. Since the surface to be treated 13 is dissolved and 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) is formed, the metal foil layer 13 is corroded. A 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.} If mass is more than the said lower limit, the effect which suppresses that the metal foil layer 13 is eroded by electrolyte solution will be easy to be acquired. Moreover, even if mass exceeds the said upper limit, the effect which suppresses that the metal foil layer 13 is eroded with electrolyte solution hardly changes.
In the above description, the mass per unit area is described. However, if the specific gravity is known, the thickness of the corrosion prevention treatment layer 14 can be converted therefrom.

"Second adhesive layer"
The second adhesive layer 15 is a layer that bonds 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 having reactivity with a polymer (hereinafter also referred to as “reactive compound”) contained in the layer in contact with the second adhesive layer of the corrosion prevention treatment layer 14. 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 that is reactive with the cationic polymer. When the corrosion prevention treatment layer 14 is the treatment layers (b), (d), (g), and (i), the second adhesive layer 15 contains a compound that is reactive with an anionic polymer. When the corrosion prevention treatment layer 14 is the treatment layers (c) and (h), the second adhesive layer 15 is 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 contain the two types of compounds, and may contain a compound having reactivity with both the cationic polymer and the anionic polymer.
The second adhesive layer 15 may further contain 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 are made into a crosslinked structure. Examples of the crosslinking agent include polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group.
Among these, a polyfunctional isocyanate compound is preferable because it is highly reactive with a 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.
As these glycidyl compounds, compounds having an oxazoline group, and carbodiimide compounds, the oxazoline compounds and carbodiimide compounds exemplified above in the description of the first adhesive layer, and the cross-linking agents for forming a cationic polymer as a cross-linking structure are exemplified above. Glycidyl compounds, compounds having an oxazoline group, and the like.
Among these, a glycidyl compound is preferable in terms of high reactivity with an anionic polymer.

When the second adhesive layer 15 includes an acid-modified polyolefin resin, which will be described later, the reactive compound may be reactive with an acidic group in the acid-modified polyolefin resin (that is, form a covalent bond with the acidic group). preferable. Thereby, adhesiveness with the corrosion prevention process layer 14 increases more. In addition, the acid-modified polyolefin resin has a crosslinked structure, and the solvent resistance of the exterior material 10 is further improved.
The content of the reactive compound is preferably equivalent to 10 times equivalent to the acidic group in the acid-modified polyolefin resin. When the amount is equal to or greater than the amount, the reactive compound sufficiently reacts with the acidic group in the acid-modified polyolefin resin. On the other hand, if it exceeds 10 times the equivalent amount, the cross-linked structure with the acid-modified polyolefin resin becomes insufficient, and there is a concern that physical properties such as the above-mentioned solvent resistance will be lowered.

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 preferable.
Examples of the acid-modified polyolefin resin having a carboxy group introduced into a 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 acid anhydride and the ester of the unsaturated carboxylic acid or its acid anhydride are sometimes 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, propylene-α olefin copolymer, and the like.
As unsaturated carboxylic acid, 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, etc. Is mentioned.
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.
Examples of the unsaturated carboxylic acid or its anhydride ester include methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconic acid, Examples thereof include dimethyl tetrahydrophthalic anhydride and dimethyl bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylate.

The ratio of the graft compound in the acid-modified polyolefin resin is preferably 0.2 to 100 parts by mass with respect to 100 parts by mass of the polyolefin resin.
The temperature condition for the graft reaction is preferably 50 to 250 ° C, more 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, the residence time of the extruder is preferable. Specifically, 2 to 30 minutes is preferable, and 5 to 10 minutes is more preferable.
The grafting reaction can be carried out under both normal pressure and pressurized conditions.
Examples of the radical initiator include organic peroxides. Examples of the organic peroxide include alkyl peroxides, aryl peroxides, acyl peroxides, ketone peroxides, peroxyketals, peroxycarbonates, peroxyesters, hydroperoxides, and the like. These organic peroxides can be appropriately selected depending on temperature conditions and reaction time. In the case of the melt graft reaction by the above-described twin-screw extruder, alkyl peroxide, peroxyketal, and peroxyester are preferable, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butyl. Peroxy-hexyne-3 and dicumyl peroxide are more preferred.

Various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier may be added to the second adhesive layer 15.
In addition, the silane coupling agent may be contained in the common adhesive agent used in order to adhere | attach a metal foil layer and a sealant layer. This is because the adhesion is promoted by adding a silane coupling agent to increase the adhesive strength. However, when an adhesive containing a silane coupling agent is used, depending on the type of 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 added. This may cause a reaction and cause a harmful effect on the original intended crosslinking 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 contain 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 in contact with the second adhesive layer of the corrosion prevention treatment layer 14 and corrodes. The adhesive strength between the prevention treatment layer 14 and the second adhesive layer 15 is improved. Therefore, sufficient adhesive strength can be obtained without adding a silane coupling agent to the second adhesive layer 15 for the purpose of promoting adhesion. Therefore, when there is a possibility that the crosslinking reaction may be adversely affected, it is preferable that the second adhesive layer 15 does not contain a silane coupling agent.

  3-50 micrometers is preferable and, as for the thickness of the 2nd adhesive bond layer 15, 10-40 micrometers is more preferable. If the thickness of the 2nd adhesive bond layer 15 is more than a lower limit, the outstanding adhesiveness will be easy to be obtained. If the thickness of the 2nd adhesive bond layer 15 is below an upper limit, the water | moisture content permeate | transmitted from the side end surface of the exterior material 10 will be 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 constituting the sealant layer 16 include a polyolefin resin or an acid-modified polyolefin resin. Examples of these polyolefin resin and 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 function required, 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, various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier may be added to the sealant layer 16.
The thickness of the sealant layer 16 is preferably 10 to 100 μm, and more preferably 20 to 50 μm.

"Method of manufacturing exterior materials for lithium batteries"
The exterior material 10 shown in FIG. 1 can be manufactured by the manufacturing method which has the following processes (1)-(3), for example.
(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 bonding the sealant layer 16 to the side of the metal foil layer 13 on which the corrosion prevention treatment layer 14 is formed via the second adhesive layer 15.

Step (1):
The corrosion prevention treatment layer 14 can be formed by performing the above-described corrosion prevention treatment on one surface of the metal foil layer 13. Specific examples of the formation method include the methods exemplified above in the description of the formation method of the treatment layers (a) to (j).
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 that has been degreased by a wet type or a dry type may be used.

Step (2):
As a 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, dry lamination, Known methods such as non-solvent lamination and wet lamination can be employed. Among these, it is preferable to use a dry lamination method.
As the adhesive forming the first adhesive layer 12, the polyurethane adhesive described in the first adhesive layer 12 is preferable.
The dry coating amount of the adhesive is preferably 1 to 10 g / m ^{2 and} more preferably 3 to 7 g / m ² .
After the base material layer 11 is bonded to the other surface of the metal foil layer 13, an aging (curing) treatment may be performed within a range of room temperature to 100 ° C for promoting adhesion.

Step (3):
Examples of a method for 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 include a wet process and a dry process.
In the case of the wet process, first, a corrosion-diluted product or dispersion of an adhesive containing a cationic polymer or a compound reactive with an anionic polymer and, if necessary, an acid-modified polyolefin resin or the like, is added to the corrosion prevention treatment layer 14. Apply on top. Next, after volatilizing the solvent at a predetermined temperature (if the adhesive contains an acid-modified polyolefin resin, a temperature equal to or higher than its melting point), the sealant layer 16 is bonded by a dry lamination method or the like, or the solvent is volatilized. Further, after heating and melting and softening at a temperature equal to or higher than the melting point of the polymer, baking is performed, and then the sealant layer 16 is laminated by a heat treatment such as a thermal lamination method to obtain the exterior material 10.
As a coating method, the various coating methods illustrated previously in description of the formation method of process layer (a)-(c) are mentioned.

In the case of a dry process, first, an adhesive containing a cationic polymer or a compound reactive with an anionic polymer and, if necessary, an acid-modified polyolefin resin is extruded onto the corrosion prevention treatment layer 14 by extrusion lamination or the like. Then, the second adhesive layer 15 is formed. Next, the sealant layer 16 formed in advance by an inflation method or a casting method is laminated by sandwich extrusion lamination or the like to obtain the exterior material 10.
A multilayer film is produced by co-extrusion of the adhesive constituting the second adhesive layer 15 and the resin constituting the sealant layer 16 by an inflation method or a casting method, and the multilayer film is subjected to the corrosion prevention treatment layer 14. It is also possible to laminate them by thermal lamination.
Further, if necessary, 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 layer structure as described above 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 holding in a hot roll, and a method of pressure bonding with a hot roll. The temperature of the heat treatment is preferably 40 ° C. or more in the case of aging treatment, and 150 ° C. or more in the case of a method of holding in a heat roll or a method of pressure bonding with a heat roll (however, when the adhesive contains an acid-modified polyolefin resin, The temperature above its melting point) is preferred.

"Effect"
The exterior material of the present embodiment described above includes 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 consists of a laminated body. The corrosion prevention treatment layer includes at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer in a layer in contact with at least the second adhesive layer. The corrosion prevention treatment layer is formed by subjecting the metal foil layer to at least one treatment selected from the group consisting of a degreasing treatment, a hydrothermal alteration treatment, an anodizing treatment, and a chemical conversion treatment. On the other hand, the second adhesive layer is a layer containing a compound (reactive compound) having reactivity 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 this 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 bond adhesive interface tends to have a higher adhesion strength between layers than a laminate having a hydrogen bond adhesive interface.

As described above, since the electrolytic solution is highly permeable to the sealant layer, the electrolytic solution and hydrofluoric acid generated by hydrolysis of the lithium salt as the electrolyte are interposed between the corrosion prevention treatment layer and the adhesive layer. To penetrate.
However, in the case of the exterior material of the present embodiment, a covalent bond adhesive interface is formed between the corrosion prevention treatment layer and the second adhesive layer, so that even if the electrolyte or hydrofluoric acid penetrates A decrease in laminate strength can be suppressed. Therefore, the exterior material of this invention is excellent in electrolyte solution resistance.
Moreover, in the case of the exterior material of the present embodiment, the corrosion prevention treatment layer and the second adhesive layer are firmly bonded to each other by the formation of the covalent bonding interface, so that a high laminate strength is exhibited even in a short aging time. .

  The corrosion prevention treatment layer is formed by subjecting the metal foil layer to at least one treatment selected from the group consisting of a degreasing treatment, a hydrothermal alteration treatment, an anodizing treatment, and a chemical conversion treatment. The layer formed by these corrosion prevention treatments serves to suppress corrosion of the metal foil layer due to hydrofluoric acid generated by the reaction between the electrolytic solution and moisture. In addition, it improves the adhesion with the second adhesive layer by improving the interaction with the metal foil layer.

In general, a lithium battery is manufactured by, for example, molding an exterior material into a pocket shape by cold molding, and sealing a cell, an electrolytic solution, or the like that is a main body of the battery. If the adhesion strength between the anticorrosion treatment layer and the second adhesive layer is insufficient, the stress is concentrated at the interface between the anticorrosion treatment layer and the second adhesive layer during the cold forming, and the fineness is reduced. Floating may occur. When the fine float occurs, the electrolytic solution penetrates and the insulating property is easily lowered.
However, in the case of the exterior material according to the present embodiment, a covalent bond adhesive interface is formed between the second corrosion prevention treatment layer and the second adhesive layer, so that even if cold forming is performed, corrosion is caused. Fine floating is unlikely to occur at the interface between the prevention treatment layer and the second adhesive layer, and a good adhesion interface can be formed, so that insulation can be ensured.

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

  While preferred embodiments of the present invention have been described and described above, it should be understood that these are exemplary 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. Accordingly, the invention is not to be seen as limited by the foregoing description, but is limited by the scope of the claims.

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

"Materials 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 composed of 90 parts by mass of polyallylamine and 10 parts by mass of a glycidyl compound, 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 oxazoline group (copolymer obtained by copolymerizing 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 in which a polyisocyanate compound having an isocyanurate structure is blended at 10 parts by mass (solid content ratio) with respect to 100 parts by mass of a maleic anhydride-modified polyolefin resin dissolved in toluene. The compounding quantity of a polyisocyanate compound is 3 times equivalent with respect to the acidic group (carboxy group) of maleic anhydride modified polyolefin resin.
C-2: The adhesive composition which mix | blended the glycidyl compound with 10 mass parts (solid content ratio) with respect to 100 mass parts of maleic anhydride modified polyolefin resin dissolved in toluene. The compounding quantity of a glycidyl compound is 5 times equivalent with respect to the acidic group (carboxy group) of 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) is 2.

"Example 1"
First, after applying chromate treatment to one surface of a metal foil layer made of aluminum foil to form A-1, B-1 was applied on A-1 and dried to form a corrosion prevention treatment layer. . The coating of B-1 was performed by micro gravure coating. The coating amount of B-1 was 70 to 100 mg / m ² .
Next, a polyurethane adhesive (A525 / A52 manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.) is dried on the other side of the metal foil layer (the side opposite to the side on which the anticorrosion treatment layer is formed) by a dry laminating method. Coating was performed at a coating amount of 4 to 5 mg / m ² to form a first adhesive layer. A base material layer made of a polyamide film was bonded through the first adhesive layer.
Subsequently, C-1 was applied onto the corrosion prevention treatment layer by a dry lamination method 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 is laminated as a sealant layer through the second adhesive layer, and as shown in FIG. 1, substrate layer 11 / first adhesive layer 12 / metal foil layer 13 / corrosion A laminate having a layer configuration of prevention treatment layer 14 / second adhesive layer 15 / 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 of 100 × 15 mm size to make a sample for evaluation, and the electrolytic solution resistance shown below was evaluated. The results are shown in Table 1.
An electrolyte was prepared by adding LiPF ₆ to a solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) to 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. Then, the sample was taken out from the container and further immersed in water for 2 hours. The peeling condition of the sample after immersion was evaluated according to the following criteria. In addition, the case where the evaluation of the first electrolytic solution property of the exterior material obtained by aging for 5 days is “◯” or “◎” is accepted.
A: Laminate strength is 10 N / 15 mm or more (crosshead speed is 300 mm / min).
A: The laminate strength is 5 N / 15 mm or more and less than 10 N / 15 mm (crosshead speed is 300 mm / min).
Δ: Laminate strength is less than 5 N / 15 mm (crosshead speed is 300 mm / min).
X: Delamination occurs and the laminate strength cannot be measured.

(Insulation evaluation)
Each of the obtained exterior materials was molded into a pocket shape 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 by evaluating the electrolytic solution resistance as a content was accommodated, and the lid was covered with an unmolded exterior material. At this time, the molded product and the unmolded exterior material were overlapped so that the sealant layers face each other and sealed by heat sealing to obtain a molded sample. Also, when heat-sealing, the aluminum tab lead (Al tab lead) together with the tab film made of acid-modified polyolefin film, one end is immersed in the electrolyte and the other end comes out of the molded sample and molded. Sealing was performed by interposing between the outer packaging material and the outer packaging material.
Part of the surface (outer layer) of the resulting molded sample is scraped with a file to intentionally expose the 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: The insulation resistance value is 50 MΩ or more and less than 100 MΩ.
X: The insulation resistance value is less than 50 MΩ.

"Examples 2-4, Comparative Examples 1-4"
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. The results are shown in Table 1.

As is clear from Table 1, the packaging material obtained in each example was excellent in resistance to electrolyte and insulation.
On the other hand, the packaging 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 caused delamination and were inferior in electrolytic solution resistance. Moreover, since the delamination generate | occur | produced in the exterior material obtained by Comparative Examples 1-3, insulation evaluation was not implemented.
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 reactive with the cationic polymer has a sufficient laminate strength when the aging days are short. It was not obtained and was inferior in electrolysis resistance. Moreover, although the exterior material obtained in Comparative Example 4 showed an insulation resistance value that could be used as a consumer battery, it was inferior in insulation as compared with the exterior material obtained in each Example.

  According to the present invention, it is possible to obtain an exterior material for a lithium battery that exhibits high laminate strength even in a short aging time, is excellent in electrolytic solution resistance, and can ensure insulation even when cold-molded.

DESCRIPTION OF SYMBOLS 10 Lithium battery exterior material 11 Base material layer 12 1st adhesive layer 13 Metal foil layer 14 Corrosion prevention treatment layer 15 2nd adhesive layer 16 Sealant layer

Claims (7)

Laminate in which a base material layer, a first adhesive layer, a metal foil layer, a corrosion prevention treatment layer having a single layer configuration or a multilayer configuration, a second adhesive layer, and a sealant layer are stacked in this order. Composed of the body,
The corrosion prevention treatment layer is provided on at least the second adhesive layer side, and includes at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer in a layer in contact with at least the second adhesive layer, and The corrosion prevention treatment layer is formed by subjecting the metal foil layer to at least one treatment selected from the group consisting of degreasing treatment, hydrothermal alteration treatment, anodizing treatment, and chemical conversion treatment,
A 2nd adhesive bond layer is a lithium battery exterior material containing the compound which has the reactivity with the said polymer contained in the layer which contact | connects said 2nd adhesive bond layer. The corrosion prevention treatment layer includes a cationic polymer in a layer in contact with the second adhesive layer,
The compound having reactivity with the cationic polymer contained in the second adhesive layer is at least one 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. The lithium battery exterior material according to claim 1, wherein   Cationic polymer is polyethyleneimine, ionic polymer complex composed of polyethyleneimine and polymer having carboxylic acid, primary amine-grafted acrylic resin in which primary amine is grafted on acrylic main skeleton, polyallylamine or its derivative, aminophenol The external packaging material for lithium batteries according to claim 2, which is at least one selected from the group consisting of: The corrosion prevention treatment layer includes an anionic polymer in a layer in contact with the second adhesive layer,
The compound having reactivity with the anionic polymer contained in the second adhesive layer is at least one selected from the group consisting of a glycidyl compound, a compound having an oxazoline group, and a carbodiimide compound. Exterior material for lithium batteries.   The anionic polymer is a polymer having a carboxy group, and the polymer is a copolymer obtained by copolymerizing poly (meth) acrylic acid or a salt thereof, or a monomer mixture containing (meth) acrylic acid or a salt thereof. The packaging material for lithium batteries according to claim 4.   The exterior material for a lithium battery according to any one of claims 1 to 5, wherein the second adhesive layer further contains an acid-modified polyolefin resin.   The exterior for lithium batteries according to any one of claims 1 to 6, wherein a corrosion prevention treatment layer having a single layer structure or a multilayer structure is provided between the first adhesive layer and the metal foil layer. Wood.

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