JP6428906B2 - Lithium battery exterior materials - Google Patents

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.

As an adhesive for adhering the sealant layer and the metal foil layer, generally, a polyurethane-based adhesive in which a polyfunctional isocyanate compound is blended with a diol component has been used.
However, the polyurethane-based adhesive was easily swollen with respect to the organic solvent. In addition, the urethane bond was inferior in durability to the electrolytic solution and hydrofluoric acid.

  Therefore, for example, Patent Document 1 discloses a polyolefin resin having a carboxy group as an exterior 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. And a packaging material in which a sealant layer and a metal foil layer are bonded via a layer (adhesive layer) made of an adhesive containing a polyfunctional isocyanate compound.

JP 2010-92703 A

  However, in the exterior material described in Patent Document 1, it is not always easy to develop excellent electrolytic solution resistance over a long period of time, and further improvement in electrolytic solution resistance is required.

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.

  This invention is made | formed in view of the said situation, and it aims at provision of the exterior material for lithium batteries which can express the outstanding electrolyte solution resistance over a long period of time.

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, a second adhesive layer, and a sealant layer are composed of a laminated body laminated in this order, The second adhesive layer is composed of an adhesive composition containing an acid-modified polyolefin resin and a polyfunctional isocyanate compound. In the infrared absorption spectrum of the second adhesive layer, the CH _{3 has} a C—H bending vibration. An exterior material for a lithium battery, wherein the ratio (Y / X) of the derived absorption (X) to the absorption (Y) derived from N-H bending vibration of burette bond is 0.3 or less.
[2] The lithium battery exterior material according to [1], wherein the polyfunctional isocyanate compound has an isocyanurate structure.
[3] The acid-modified polyolefin resin is a homopolymer of propylene or a copolymer of propylene and ethylene, unsaturated carboxylic acid, acid anhydride of unsaturated carboxylic acid, ester of unsaturated carboxylic acid, unsaturated carboxylic acid. The outer packaging material for a lithium battery according to [1] or [2], which is an acid-modified polyolefin resin grafted with at least one selected from the group consisting of esters of acid anhydrides.
[4] The lithium composition according to any one of [1] to [3], wherein the adhesive composition further includes an organometallic catalyst including at least one metal selected from the group consisting of tin, titanium, and zirconium. Battery exterior material.

  The outer packaging material for a lithium battery of the present invention can exhibit excellent electrolytic solution resistance over a long period of time.

It is sectional drawing which shows an example of the exterior material for lithium batteries of this invention. It is an infrared absorption spectrum of the 2nd adhesive bond layer which consists of an adhesive composition used in Example 1, 4. It is an infrared absorption spectrum of the 2nd adhesive bond layer which consists of an adhesive composition used in Example 2, 5. It is an infrared absorption spectrum of the 2nd adhesive bond layer which consists of an adhesive composition used in Example 3, 6. FIG. It is an infrared absorption spectrum of the 2nd adhesive bond layer which consists of an adhesive composition used in Comparative Examples 1 and 2.

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.
As shown in FIG. 1, the exterior material 10 of this embodiment includes a base material layer 11, a first adhesive layer 12, a one-layer corrosion prevention treatment layer 13, a metal foil layer 14, and two layers. The corrosion prevention treatment layer 15, the second adhesive layer 16, and the sealant layer 17 are configured from 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 17 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.

  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 1st adhesive bond layer 12 is a layer which adhere | attaches the base material layer 11 and the metal foil layer 14 in which the corrosion prevention process layer 13 was formed.
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, speric acid, azelaic acid, sebacic acid, and brassic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, and the like. 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 an attached xylylene glycol, and aromatic diols such as a 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.

  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, 3-5 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 14 in a liquid atmosphere can be sufficiently suppressed.

"Metal foil layer"
The metal foil layer 14 has a water vapor barrier property that prevents moisture from entering the battery. Moreover, the metal foil layer 14 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 14, 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 14, a known soft aluminum foil can be used, and an aluminum foil containing iron is preferable from the viewpoint of pinhole resistance and extensibility during 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 14, 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 by increasing the treatment time 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 layers 13 and 15 are layers provided to prevent the metal foil layer 14 from being corroded by the electrolytic solution or hydrofluoric acid.
In the present invention, the corrosion prevention treatment layer 13 between the first adhesive layer 12 and the metal foil layer 14 is referred to as an “outer layer side corrosion prevention treatment layer 13”, and the metal foil layer 14 and the second adhesive layer. Corrosion prevention treatment layer 15 between 16 is also referred to as “inner layer side corrosion prevention treatment layer 15”.

The inner layer side corrosion prevention treatment layer 15 is a layer containing a rare earth element oxide and 1 to 100 parts by mass of phosphoric acid or phosphate with respect to 100 parts by mass of the rare earth element oxide. The inner layer side corrosion prevention treatment layer 15 preferably further includes at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer, and the electrolytic solution resistance and hydrofluoric acid resistance of the exterior material 10 are further improved. From the viewpoint, the inner layer side corrosion prevention treatment layer 15 particularly preferably contains a cationic polymer.
In addition, when providing coating layers, such as the corrosion prevention process layers 13 and 15, on the metal foil layer 14, generally the technique which improves an interface adhesive force using a silane coupling agent may be used. 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. Therefore, it is preferable that the corrosion prevention treatment layers 13 and 15 do not contain a silane coupling agent.

As shown in FIG. 1, the inner layer side corrosion prevention treatment layer 15 of the present embodiment has a two-layer configuration of a first inner layer side corrosion prevention treatment layer 15a and a second inner layer side corrosion prevention treatment layer 15b. .
The first inner layer side corrosion prevention treatment layer 15a is a layer in contact with the metal foil layer 14, and contains a rare earth element oxide and phosphoric acid or phosphate. The second inner layer side corrosion prevention treatment layer 15b is a layer in contact with the second adhesive layer 16 described later, and includes at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer.
The second inner layer side corrosion prevention treatment layer 15b preferably contains a cationic polymer or an anionic polymer. From the viewpoint of further improving the electrolytic solution resistance and hydrofluoric acid resistance of the outer packaging material 10, the second inner layer side corrosion prevention layer 15b. It is particularly preferable that the prevention treatment layer 15b includes a cationic polymer.

Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide. Among these, cerium oxide is preferable from the viewpoint of electrolyte resistance.
When forming the first inner layer side corrosion prevention treatment layer 15a, phosphoric acid or phosphate is used as a dispersion stabilizer, and a rare earth element oxide is dispersed and stabilized to form a sol (rare earth element Oxide sol) may be used. The rare earth element oxide sol is obtained by dispersing rare earth element oxide fine particles (for example, particles having an average particle diameter of 100 nm or less) in a liquid dispersion medium.
Examples of the liquid dispersion medium of the rare earth element oxide sol include various solvents such as an aqueous solvent, an alcohol solvent, a hydrocarbon solvent, a ketone solvent, an ester solvent, and an ether solvent, and an aqueous solvent is preferable.

  Phosphoric acid or phosphate not only stabilizes the dispersion of rare earth element oxides, but also improves adhesion to metal foil layers (especially aluminum foil layers) using the ability of aluminum chelates of phosphoric acid, Capturing of aluminum ions eluted by the influence (that is, formation of a passive state) gives the electrolyte solution resistance, and the cohesive strength of the first inner layer side corrosion prevention treatment layer 15a due to the dehydration condensation of phosphoric acid easily even at low temperatures. Improvements can be expected. By improving the cohesive force, the strength properties of the exterior material 10 tend to be good.

Examples of the phosphoric acid compound such as phosphoric acid or phosphate include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, or alkali metal salts and ammonium salts thereof. In addition, various salts such as aluminum phosphate and titanium phosphate may be used. In terms of function expression, condensed phosphoric acid such as trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid and ultrametaphosphoric acid, or alkali metal salts and ammonium salts (condensed phosphates) thereof are preferable.
In particular, when the first inner layer side corrosion prevention treatment layer 15a is formed by using a rare earth element oxide in a sol state (that is, a rare earth element oxide sol), the dry film forming property (that is, the drying ability and the amount of heat) is taken into consideration. Then, the dispersion stabilizer which is excellent in the reactivity at low temperature is preferable. For this reason, as a salt forming a phosphate, a sodium salt that is excellent in dehydration condensation property at low temperature is preferable. The phosphate compound is preferably a water-soluble salt.

  Content of phosphoric acid or its salt is 1-100 mass parts with respect to 100 mass parts of rare earth element oxides, 5-50 mass parts is preferable, and 5-20 mass parts is more preferable. When the content of phosphoric acid or a salt thereof is not less than the above lower limit, the stability of the rare earth element oxide sol is improved, and the exterior material 10 having a sufficient function can be obtained. On the other hand, if the content of phosphoric acid or a salt thereof is not more than the above upper limit value, the function of the rare earth element oxide sol is enhanced, and the first inner layer side corrosion prevention treatment layer 15a excellent in performance of preventing erosion of the electrolytic solution. Is formed.

The thickness of the first inner layer side corrosion prevention treatment layer 15a is not particularly limited, but is preferably 0.01 to 10 μm.
The mass a per unit area of the first inner side corrosion prevention-treated layer 15a, it is preferably 0.010~0.200g / ^{m 2,} a 0.040~0.100g / ^{m 2} Is more preferable. If the mass a is smaller than the lower limit, the absolute amount of rare earth element oxide, phosphoric acid or phosphate, which has an effect of preventing corrosion of a metal foil such as an aluminum foil, is reduced, so that the electrolytic solution resistance and hydrofluoric acid resistance are reduced. Is difficult to obtain. On the other hand, when the mass a is larger than the above upper limit value, the sol-gel reaction accompanying drying of the rare earth element oxide sol becomes difficult to proceed (that is, the amount of heat becomes insufficient and the sol-gel reaction becomes difficult to proceed). The cohesive strength of the oxide sol is reduced, which may reduce the strength properties when used as an exterior material. Accordingly, if the mass a per unit area of the first inner layer side corrosion prevention treatment layer 15a is within the above range, the electrolytic solution resistance can be maintained and the cohesive strength of the rare earth element oxide sol can be maintained. Sufficient strength can be imparted to the material.

The cationic polymer is a compound that is excellent in resistance to electrolytic solution and hydrofluoric acid. The reason for this is presumed to be to suppress damage to the aluminum foil by trapping fluorine ions with a cation 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 second inner layer side corrosion prevention treatment layer 15b. 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 forming the second inner layer side corrosion prevention treatment layer 15b. Examples of the crosslinking agent for making the cationic polymer into a crosslinked structure 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.

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.

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. Moreover, as a method of crosslinking the cationic polymer, besides using the above-mentioned crosslinking agent, a method of forming a crosslinked structure such as ionic crosslinking using titanium or a zirconium compound as a crosslinking agent may be used.
A crosslinking agent may be used individually by 1 type, and may use 2 or more types together.

Further, a silane coupling agent capable of selectively reacting an amine and a functional group to form a siloxane bond at the crosslinking point may be used in combination with the crosslinking agent. It is preferable that the layer 15 does not contain a silane coupling 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 second inner layer side corrosion prevention treatment layer 15b.
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 second inner layer side corrosion prevention treatment layer 15b contains an anionic polymer, ion contamination such as sodium ions contained in the rare earth element oxide sol 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 polymers having a carboxy group, and examples include poly (meth) acrylic acid or a salt thereof, or a copolymer having (meth) acrylic acid or a salt thereof as a main component. The components used as the copolymer include 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. Alkyl (meth) acrylate monomers having an alkyl group; (meth) acrylamide, N-alkyl (meth) acrylamide and N, N-dialkyl (meth) acrylamide (alkyl groups include methyl, ethyl and n-propyl groups) , 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, (Examples of alkoxy groups include methoxy, ethoxy, butoxy, and isobutoxy groups), N-methyl Amide group-containing monomers such as diol (meth) acrylamide and N-phenyl (meth) acrylamide; Hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; Glycidyl (meth) acrylate, Glycidyl group-containing monomers such as allyl glycidyl ether; Silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane and (meth) acryloxypropyltriethoxylane; and isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate Polymerized ones can be mentioned.

It is preferable that the anionic polymer also forms a crosslinked structure in the second inner layer side corrosion prevention treatment layer 15b. 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 forming the second inner layer side corrosion prevention treatment layer 15b. 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.
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, although you may use together a crosslinking agent and a silane coupling agent, as above-mentioned, it is preferable that the inner layer side corrosion prevention process layer 15 does not contain a silane coupling agent. Examples of the silane coupling agent include the silane coupling agents exemplified above in the description of the cationic polymer.

  As shown in FIG. 1, the first inner layer side corrosion prevention treatment layer 15 a is directly laminated on the metal foil layer 14. The first inner layer side corrosion prevention treatment layer 15a has a structure in which sol particles of rare earth element oxides are substantially concentrated. On the other hand, the second inner layer side corrosion prevention treatment layer 15b is laminated on the first inner layer side corrosion prevention treatment layer 15a while filling the gap between the first inner layer side corrosion prevention treatment layers 15a where the sol particles are densely packed. ing. That is, the material containing at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer constituting the second inner layer side corrosion prevention treatment layer 15b (hereinafter also referred to as “coating composition (b)”). ) Is applied on the first inner layer side corrosion prevention treatment layer 15a while penetrating into the gaps between the first inner layer side corrosion prevention treatment layers 15a to form the second inner layer side corrosion prevention treatment layer 15b. At this time, the coating composition (b) that has penetrated into the gaps of the first inner layer side corrosion prevention treatment layer 15a is thermally crosslinked, so that the second inner layer side corrosion prevention treatment layer 15b becomes the first inner layer side corrosion prevention treatment layer 15b. The effect of the protective layer of the treatment layer 15a is expressed.

In order for the second inner layer side corrosion prevention treatment layer 15b to more effectively express the protective layer role of the first inner layer side corrosion prevention treatment layer 15a, a unit of the first inner layer side corrosion prevention treatment layer 15a is used. The relationship between the mass a (g / m ² ) per area and the mass b (g / m ² ) per unit area of the second inner layer side corrosion prevention treatment layer 15b satisfies 2 ≧ b / a. preferable.
Even when the mass relationship (b / a) of each layer exceeds the above range, it is possible that the second inner layer side corrosion prevention treatment layer 15b can serve as a protective layer for the first inner layer side corrosion prevention treatment layer 15a. However, in this case, in addition to the ratio of filling the gap of the first inner layer side corrosion prevention treatment layer 15a, the second inner layer side corrosion prevention treatment layer laminated on the first inner layer side corrosion prevention treatment layer 15a. The ratio of 15b will increase more than necessary. The cationic polymer and / or the anionic polymer in the second inner layer side corrosion prevention treatment layer 15b are present in the second inner layer side corrosion prevention treatment layer 15b rather than being present alone. The composite with the rare earth element oxide, phosphoric acid or phosphate in the layer 15a tends to more effectively express the electrolytic solution resistance and hydrofluoric acid resistance functions. Therefore, when the relationship (b / a) of the mass of each layer exceeds the above range, as a result, it is not compounded with the rare earth element oxide, phosphoric acid or phosphate in the first inner layer side corrosion prevention treatment layer 15a. As the proportion of the cationic polymer and / or anionic polymer present alone in the liquid crystal increases, the electrolytic solution resistance and hydrofluoric acid resistance functions may not be fully exerted, and the electrolytic solution resistance and hydrofluoric acid resistance decrease. There is a fear. Moreover, since the coating amount of a coating composition (b) increases, it may become difficult to harden | cure. In order to sufficiently cure the coating composition (b), the drying temperature may be set high or the curing time may be set long. As a result, the productivity may be lowered. Therefore, from the viewpoint of improving the electrolytic solution resistance and hydrofluoric acid resistance while maintaining the productivity, the mass relationship (b / a) of each layer is preferably 2 ≧ b / a, and 1.5 ≧ b /A≧0.01 is more preferable, and 1.0 ≧ b / a ≧ 0.1 is particularly preferable.
In addition, although the said relationship is based on the mass of a layer, if the specific gravity of each layer can be calculated | required, it can also convert into the thickness of the inner layer side corrosion prevention process layer 15 whole.

The outer layer side corrosion prevention treatment layer 13 is not particularly limited as long as it can prevent corrosion of the metal foil layer 14. For example, the rare earth element oxide and 1 to 100 parts by mass with respect to 100 parts by mass of the rare earth element oxide. It is preferable to contain phosphoric acid or phosphate. Furthermore, a cationic polymer or an anionic polymer may be contained, and these polymers may form a crosslinked structure with a crosslinking agent. However, as described above, it is preferable that the outer layer side corrosion prevention treatment layer 13 does not contain a silane coupling agent.
As the rare earth element oxide, phosphoric acid or phosphate, cationic polymer, anionic polymer, and crosslinking agent, the rare earth element oxide, phosphoric acid or phosphate exemplified above in the description of the inner layer side corrosion prevention treatment layer 15 , Cationic polymer, anionic polymer, cross-linking agent and the like.

"Second adhesive layer"
The second adhesive layer 16 is a layer that bonds the metal foil layer 14 on which the inner layer side corrosion prevention treatment layer 15 is formed and the sealant layer 17.
The second adhesive layer 16 of this embodiment is a layer made of an adhesive composition containing an acid-modified polyolefin resin and a polyfunctional isocyanate compound.

The second adhesive layer 16 has the following characteristics.
That is, in the infrared absorption spectrum of the second adhesive layer 16, the absorption (X) derived from CH ₃ CH bending vibration and the absorption derived from N—H bending vibration of buret bond (Y ) (Y / X) is 0.3 or less.
The CH ₃ CH bending vibration has a peak (absorption peak) in the region of 1380 ± 10 cm ⁻¹ . This C—H bending vibration is derived from CH ₃ in the acid-modified polyolefin resin contained in the adhesive composition. Absorption (X) derived from CH ₃ CH bending vibration is the intensity of the peak appearing in the region of 1380 ± 10 cm ⁻¹ .
On the other hand, the peak (absorption peak) appears in the 1520 ± 10 cm ⁻¹ region of the N—H bending vibration of burette coupling. This N—H bending vibration is derived from a burette bond in the second adhesive layer 16 made of the adhesive composition. Absorption (Y) derived from N-H bending vibration of burette bond is the intensity of the peak appearing in the region of 1520 ± 10 cm ⁻¹ .

The burette bond is contained in the polyfunctional isocyanate compound itself, or occurs when the polyfunctional isocyanate compound causes a side reaction (burette reaction) with water in the adhesive composition or in the atmosphere.
The polyfunctional isocyanate compound contains a burette bond mainly when a burette body is used as the polyfunctional isocyanate compound. In addition, since a burette body may be mixed as a by-product when an adduct body or isocyanurate body is produced, even when an adduct body or isocyanurate body is used as a polyfunctional isocyanate compound, Let coupling may be included.
In addition, the burette reaction is likely to occur during the aging treatment that is performed as necessary during storage of the polyfunctional isocyanate compound or in the production of the exterior material 10. The aging treatment is aimed at promoting adhesion, and is performed, for example, after the metal foil layer 14 and the base material layer 11 are bonded together or after the metal foil layer 14 and the sealant layer 17 are bonded together. As the storage temperature and aging temperature increase, the burette reaction tends to proceed easily.

When the proportion of the burette bond in the adhesive composition increases, the reason for this is not clear, but the resistance to electrolytic solution decreases.
Y / X is an index of the ratio of the burette bond in the second adhesive layer 16. It means that the smaller the value of Y / X, the smaller the proportion of burette bonds contained in the polyfunctional isocyanate compound, and the side reaction (burette reaction) between the polyfunctional isocyanate compound and water is suppressed. If Y / X is 0.3 or less, the ratio of the burette bond in the second adhesive layer 16 is sufficiently reduced, so that excellent electrolytic solution resistance can be expressed over a long period of time.

Y / X can be controlled by suppressing the side reaction (burette reaction) between the polyfunctional isocyanate compound and the polyfunctional isocyanate compound and the acid-modified polyolefin resin.
For example, if a highly pure isocyanurate body (that is, a by-product burette body is sufficiently removed) is used as the polyfunctional isocyanate compound, the value of Y / X can be reduced. In addition, if the aging temperature is lowered in the production of the packaging material 10, side reactions can be suppressed, so that the value of Y / X can be reduced. Furthermore, a side reaction may be suppressed also by mix | blending the organometallic catalyst mentioned later with an adhesive composition.

Y / X can be determined, for example, as follows.
First, the packaging material 10 is immersed in an alkaline aqueous solution (for example, an aqueous sodium hydroxide solution) to completely dissolve the metal foil layer 14. Thereafter, for the second adhesive layer 16 remaining on the sealant layer 17 side, the exposed surface of the second adhesive layer 16 is reflected by a reflection method using FT-IR (Fourier transform infrared spectrophotometer). An infrared absorption spectrum is measured. From the obtained infrared absorption spectrum, the absorption (X) derived from the CH ₃ CH bending vibration and the absorption (Y) derived from the N-H bending vibration of the burette bond are obtained, and the ratio (Y / X) is calculated.

Here, a specific method for obtaining the absorption (X) and the absorption (Y) will be described with reference to FIG.
When the infrared absorption spectrum is measured by the above-described method, for example, an infrared absorption spectrum as shown in FIG. 2 is obtained.
Absorption (X) derived from CH ₃ C-H bending vibration is obtained from the following formula (1), and absorption (Y) derived from N-H bending vibration of burette bond is derived from the following formula (2). Desired.
Absorption (X) = (baseline transmittance) − (peak transmittance around 1380 cm ⁻¹ ) (1)
Absorption (Y) = (baseline transmittance) − (peak transmittance around 1520 cm ⁻¹ ) (2)
In the case shown in FIG. 2, the transmittance of the baseline is 100%, the transmittance of the peak near 1380 cm ⁻¹ is 60%, and the transmittance of the peak near 1520 cm ⁻¹ is 95.6%. Therefore, since the absorption (X) derived from CH ₃ C-H bending vibration of CH ₃ is 40 and the absorption (Y) derived from N-H bending vibration of the burette bond is 4.4, Y / X is 0.11.

The acid-modified polyolefin resin contained in the pressure-sensitive adhesive composition has an acidic group introduced 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 in which a carboxy group is introduced into a polyolefin resin include, for example, an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride, an unsaturated carboxylic acid ester, and an unsaturated carboxylic acid anhydride. Examples include acid-modified polyolefin resins obtained by grafting at least one selected from the group consisting of esters in the presence of a radical initiator. Hereinafter, unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, unsaturated carboxylic acid ester, and unsaturated carboxylic acid anhydride ester may be collectively referred to as “graft compound”.

Polyolefin resins include low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α olefin copolymer, homopolypropylene, block polypropylene, random polypropylene, propylene-α olefin copolymer, propylene-ethylene-α olefin copolymer. Examples thereof include a combination (multi-component copolymer). Among these, homopolypropylene (a homopolymer of propylene) and a propylene-α olefin copolymer are preferable. As the propylene-α olefin copolymer, a copolymer of propylene and ethylene is preferable.
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.

The acid-modified polyolefin resin is preferably dissolved or dispersed in an organic solvent and used in the form of a solution.
Examples of the organic solvent include aromatic organic solvents such as toluene; alicyclic organic solvents such as cyclohexane; ester organic solvents such as ethyl acetate; ketone organic solvents such as acetone.

  The acid-modified polyolefin resin has crystallinity and non-crystallinity, and can be properly used depending on the characteristics required for the exterior material 10. In consideration of the swellability, heat resistance, and solubility / dispersibility in an organic solvent of the electrolytic solution, a low crystalline acid-modified polyolefin resin is preferable.

Examples of the polyfunctional isocyanate compound contained in the pressure-sensitive adhesive composition include the polyfunctional isocyanate compounds exemplified above as the crosslinking agent for making the cationic polymer into a crosslinked structure in the description of the inner layer side corrosion prevention treatment layer 15. In particular, isocyanurate is preferred.
As described above, polyisocyanates include adducts, burettes, isocyanurates, and the like. The adduct is usually obtained by reacting diisocyanates with a polyhydric alcohol such as trimethylolpropane, and has a urethane bond. As described above, this urethane bond tends to have low resistance to the electrolytic solution and hydrofluoric acid. The burette body is usually obtained by reacting diisocyanates with water and has a burette bond. Since the burette body has an absorption band in the region of 1520 ± 10 cm ⁻¹ , when the burette body is used as the polyfunctional isocyanate compound, the absorption (Y) derived from the N—H bending vibration of the burette bond is obtained. Since Y increases, Y / X tends to increase.
Accordingly, the polyfunctional isocyanate compound is preferably an isocyanurate body (that is, an isocyanurate structure). However, if Y / X is 0.3 or less, an adduct body or a burette body may be used in combination.

The adhesive composition preferably further contains an organometallic catalyst. If the adhesive composition contains an organometallic catalyst, a side reaction (burette reaction) between the polyfunctional isocyanate compound and water may be suppressed. The reason for this is considered as follows.
The organometallic catalyst tends to promote the reaction (urea reaction) one stage before the burette reaction. When the adhesive composition contains an organometallic catalyst, an excess polyfunctional isocyanate compound contained in the adhesive composition reacts with urea. As a result, when the reaction between the polyfunctional isocyanate compound and the carbamic acid obtained by reacting the polyfunctional isocyanate compound with water, or the decarboxylation thereof, is promoted instead of the reaction forming a burette bond. Conceivable. In addition, it is considered that a urea bond is more easily formed than a burette bond, and absorption (Y) derived from N—H bending vibration of the burette bond is reduced.

Examples of the organometallic catalyst include compounds containing one or more metals such as tin, titanium, and zirconium. Specific examples include zirconium tetraacetylacetonate, zirconium tris (acetylacetonate) ethyl acetoacetate, dibutyltin dilaurate, and the like.
The content of the organometallic catalyst is preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the solid content of the adhesive composition (excluding the organometallic catalyst).

The adhesive composition may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.
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, the adhesive strength is increased, and the resistance to electrolytic solution is improved. 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, it is preferable that the adhesive composition forming the second adhesive layer 16 does not contain a silane coupling agent.
If it is this invention, since the 2nd adhesive bond layer 16 is formed from the adhesive composition mentioned above, the exterior material 10 excellent in electrolyte solution resistance is obtained. Therefore, it is not necessary to add a silane coupling agent to the adhesive composition for the purpose of promoting adhesion, and the adhesive composition preferably does not contain a silane coupling agent.

  3-50 micrometers is preferable and, as for the thickness of the 2nd adhesive bond layer 16, 10-40 micrometers is more preferable. If the thickness of the 2nd adhesive bond layer 16 is more than a lower limit, the outstanding adhesiveness will be easy to be obtained. If the thickness of the 2nd adhesive bond layer 16 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 17 is a layer that imparts sealing properties to the exterior material 10 by heat sealing.
Examples of the material constituting the sealant layer 17 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 16.

The sealant layer 17 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 17.
The thickness of the sealant layer 17 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 bonding the base material layer 11 through the first adhesive layer 12 after forming the outer layer side corrosion prevention treatment layer 13 on one surface of the metal foil layer 14.
(2) The process of forming the inner layer side corrosion prevention process layer 15 in the other surface (surface on the opposite side to the side which bonds the base material layer 11) of the metal foil layer 14. FIG.
(3) A step of bonding the sealant layer 17 to the side of the metal foil layer 14 on which the inner layer side corrosion prevention treatment layer 15 is formed via the second adhesive layer 16.

Step (1):
The outer layer side corrosion prevention treatment layer 13 is formed by applying the material forming the outer layer side corrosion prevention treatment layer 13 (hereinafter also referred to as a coating composition (c)) to one side (one side) of the metal foil layer 14. And formed by drying, curing, and baking.
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.
In addition, when using aluminum foil as the metal foil layer 14, as above-mentioned, untreated aluminum foil may be used and the aluminum foil which performed the degreasing process by the wet type or the dry type may be used.

Next, the base material layer 11 is bonded onto the outer layer side corrosion prevention treatment layer 13 via the first adhesive layer 12. As a bonding method, known methods such as dry lamination, non-solvent lamination, wet lamination, etc. 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 one surface of the metal foil layer 14, an aging (curing) treatment may be performed within a range of room temperature to 100 ° C in order to promote adhesion.

Step (2):
The inner layer side corrosion prevention treatment layer 15 is formed after the first inner layer side corrosion prevention treatment layer 15a is formed on the other surface of the metal foil layer 14 (the surface opposite to the side on which the base material layer 11 is bonded). It is obtained by forming the second inner layer side corrosion prevention treatment layer 15b.
Specifically, first, a material containing a rare earth element oxide and 1 to 100 parts by mass of phosphoric acid or phosphate with respect to 100 parts by mass of the rare earth element oxide (hereinafter referred to as “coating composition (a)”). Is also applied to one side of the metal foil layer 14 and dried, cured, and baked to form the first inner layer side corrosion prevention treatment layer 15a. Next, a material (coating composition (b)) containing 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 into a cross-linking structure as necessary. Then, coating is performed on the first inner layer side corrosion prevention treatment layer 15a, and drying, curing and baking are performed to form the second inner layer side corrosion prevention treatment layer 15b.
As a coating method, the various coating methods illustrated previously in description of a process (1) are mentioned.

Step (3):
Examples of the method of attaching the sealant layer 17 to the inner layer side corrosion prevention treatment layer 15 side of the metal foil layer 14 via the second adhesive layer 16 include a dry process and a wet process.
In the case of the dry process, the adhesive composition described in the second adhesive layer 16 described above is dry laminated on the inner layer side corrosion prevention treatment layer 15, and a sealant layer 17 obtained by an inflation method or a cast method is further provided. The exterior material 10 is manufactured by stacking. The second inner layer side corrosion prevention treatment layer 15b may be provided in-line during this extrusion lamination. Thereafter, for the purpose of improving the adhesion between the coating composition (b) and the adhesive composition, heat treatment (aging treatment, thermal lamination, etc.) can be applied. In the present invention, as described above, By forming the layer structure, it is possible to obtain the exterior material 10 having excellent adhesion even with a small amount of heat during extrusion lamination. When performing a heat treatment such as an aging treatment, the above-described burette reaction may proceed, and thus it is preferable that the aging temperature and the temperature of thermal lamination are not too high. Specifically, the aging temperature is preferably 25 to 45 ° C., and the thermal lamination temperature is preferably 30 to 40 ° C.
It is also possible to create a multilayer film with the second adhesive layer 16 and the sealant layer 17 by the inflation method or the cast method, and to laminate the multilayer film on the inner layer side corrosion prevention treatment layer 15 by thermal lamination. It is.

In the case of a wet process, the dispersion liquid of the adhesive composition that forms the second adhesive layer 16 is applied onto the inner layer side corrosion prevention treatment layer 15, and a predetermined temperature (the acid contained in the adhesive composition) is applied. The solvent is blown off at a temperature equal to or higher than the melting point of the modified polyolefin resin, and the polymer is melt-softened and baked. Thereafter, the sealant layer 17 is laminated by heat treatment such as thermal lamination to manufacture the exterior material 10.
As a coating method, the various coating methods illustrated previously in description of a process (1) are mentioned.

"Effect"
The exterior material of the present embodiment described above includes a base material layer, a first adhesive layer, a one-layer corrosion prevention treatment layer (outer layer side corrosion prevention treatment layer), a metal foil layer, and a two-layer constitution. The anti-corrosion treatment layer (inner layer side anti-corrosion treatment layer), the second adhesive layer, and the sealant layer are composed of a laminate laminated in this order.
The second adhesive layer is composed of an adhesive composition containing an acid-modified polyolefin resin and a polyfunctional isocyanate compound, and the Y / X described above is a layer of 0.3 or less.

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 according to the present embodiment, since the second adhesive layer made of a specific adhesive composition is provided, excellent electrolytic solution resistance can be expressed over a long period of time, and a decrease in laminate strength can be suppressed. .

  The inner layer side corrosion prevention treatment layer contains a rare earth element oxide and phosphoric acid or phosphate. Phosphoric acid or phosphate can not only stabilize the dispersion of the rare earth element oxide, but can also provide an inhibitory effect on the corrosion of the metal foil layer (particularly the aluminum foil layer). Furthermore, it becomes possible to improve the adhesiveness of phosphoric acid or phosphate to a metal foil layer (particularly, an aluminum foil layer), and a synergistic effect can be expressed in terms of resistance to electrolytic solution.

Furthermore, if the inner layer side corrosion prevention treatment layer is a multilayer structure comprising the first inner layer side corrosion prevention treatment layer and the second inner layer side corrosion prevention treatment layer described above, the hydrofluoric acid resistance is higher and the function is higher. It will be a thing. The reason for this is considered as follows.
Cationic and anionic polymers are very effective materials in terms of trapping hydrofluoric acid. Moreover, water resistance can also be improved by adding a crosslinking agent. Therefore, the inner layer side corrosion prevention treatment layer includes the second inner layer side corrosion prevention treatment layer 15b containing a cationic polymer or an anionic polymer as shown in FIG. Will be improved.
However, the layer containing a cationic polymer or an anionic polymer does not have a function of protecting the metal foil from corrosion. Therefore, as shown in FIG. 1, the inner layer side corrosion prevention treatment layer 15, together with the second inner layer side corrosion prevention treatment layer 15 b, is a first inner layer side corrosion prevention treatment containing a rare earth element oxide and phosphoric acid or phosphate. By adopting a multilayer structure including the treatment layer 15a, an effect of preventing corrosion of a metal foil such as an aluminum foil can be obtained.

"Other embodiments"
The packaging material of the present invention is not limited to the above-described one. The inner layer side corrosion prevention treatment layer 15 shown in FIG. 1 has a two-layer structure including a first inner layer side corrosion prevention treatment layer 15a and a second inner layer side corrosion prevention treatment layer 15b. 15 may have a single layer structure or a structure of three or more layers. For example, as a three-layer corrosion prevention treatment layer, a layer comprising a rare earth element oxide and phosphoric acid or phosphate, a layer comprising an anionic polymer, and a layer comprising a cationic polymer are sequentially laminated. A layer comprising a rare earth element oxide and phosphoric acid or a phosphate, a layer containing a cationic polymer, and a layer containing an anionic polymer in that order. However, the layer containing the rare earth element oxide and phosphoric acid or phosphate is the metal foil layer side.

  Further, the exterior material 10 shown in FIG. 1 is provided with the corrosion prevention treatment layers 13 and 15 on both surfaces of the metal foil layer 14, but at least the inner layer side of the surface of the metal foil layer 14 on the second adhesive layer 16 side. If the corrosion prevention treatment layer 15 is provided, the outer layer side corrosion prevention treatment layer 13 may not be provided on the surface of the metal foil layer 14 on the first adhesive layer 12 side.

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 cerium oxide sol prepared by blending 10 parts by mass of condensed sodium phosphate with 100 parts by mass of cerium oxide and adjusting the solid content concentration to 5% by mass using distilled water as a solvent.
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: A mixture comprising 90 parts by mass of polyacrylic acid and 10 parts by mass of a compound having an oxazoline group, adjusted to a solid content concentration of 5% by mass using distilled water as a solvent.
C-1: 10 parts by mass of condensed sodium phosphate is added to 100 parts by mass of cerium oxide, and distilled water is used as a solvent in a cerium oxide sol adjusted to a solid content concentration of 5% by mass using distilled water as a solvent. , A mixture of 90 parts by mass of polyacrylic acid adjusted to a solid content concentration of 5% by mass and 10 parts by mass of a compound having an oxazoline group in a ratio of 70:30.

<Second adhesive layer>
D-1: An adhesive composition in which hexamethylene diisocyanate having an isocyanurate structure is blended at 10 parts by mass (solid content ratio) with respect to 100 parts by mass of maleic anhydride-modified polyolefin resin dissolved in toluene.
D-2: An adhesive composition in which hexamethylene diisocyanate having a burette structure 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.
D-3: Zirconium-based reaction catalyst (zirconium tetra Adhesive composition to which 1 part by mass (solid content ratio) is added.

"Example 1"
First, C-1 was applied to one surface of a metal foil layer made of aluminum foil to form an outer layer side corrosion prevention treatment layer, and then a polyurethane adhesive (A525 / A52 manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.). ) By a dry laminating method with a dry coating amount of 4 to 5 mg / m ² to form a first adhesive layer. A base material layer made of a biaxially stretched polyamide film (film thickness: 25 μm) was bonded through the first adhesive layer.
Then, on the other side of the metal foil layer (the side opposite to the side on which the base material layer is bonded), A-1 is applied and dried to form a first inner layer side corrosion prevention treatment layer. B-1 was coated on the first inner layer side corrosion prevention treatment layer and dried to form a second inner layer side corrosion prevention treatment layer.
The coating of A-1 and B-1 was performed by microgravure coating. The dry coating amount after heating and drying combining A-1 and B-1 was set to 70 to 100 mg / m ² .
Next, D-1 was applied on the second inner layer side 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 the base layer 11 / first adhesive layer 12 / outer layer side corrosion prevention treatment layer as shown in FIG. 13 / metal foil layer 14 / first inner layer side corrosion prevention treatment layer 15a / second inner layer side corrosion prevention treatment layer 15b / second adhesive layer 16 / sealant layer 17 was obtained.
The obtained laminate was aged at 40 ° C. for 10 days to obtain an exterior material.

<Measurement / Evaluation>
The obtained exterior material was cut into a strip of 100 × 15 mm size, used as a measurement / evaluation sample, and the following infrared absorption spectrum measurement and electrolytic solution resistance evaluation were performed.

(Measurement of infrared absorption spectrum)
The sample was immersed in an aqueous sodium hydroxide solution to completely dissolve the metal foil layer made of aluminum foil. Thereafter, the second adhesive layer remaining on the sealant layer side is subjected to infrared absorption on the exposed surface of the second adhesive layer by a reflection method using FT-IR (Fourier transform infrared spectrophotometer). The spectrum was measured. This is shown in FIG. 2 as an infrared absorption spectrum of the second adhesive layer made of the adhesive composition used in Example 1 and Example 4 described later. From the obtained infrared absorption spectrum, the absorption (X) derived from CH ₃ C-H bending vibration and the absorption (Y) derived from N-H bending vibration of burette bond are represented by the following formula (1), The ratio (Y / X) was calculated from (2). The results are shown in Table 1.
Absorption (X) = (baseline transmittance) − (peak transmittance around 1380 cm ⁻¹ ) (1)
Absorption (Y) = (baseline transmittance) − (peak transmittance around 1520 cm ⁻¹ ) (2)
In FIG. 2 and FIGS. 3 to 5 described later, the transmittance of the baseline is 100%.

(Evaluation of electrolyte resistance)
An electrolyte solution prepared by adjusting LiPF ₆ to 1 M in a solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) was prepared and filled in a Teflon (registered trademark) container. After adding 1500 ppm of water, the sample was put, and after sealing, it was stored at 85 ° C. for 4 hours, 1 week, 2 weeks, and 4 weeks. Then, the sample was taken out from the container and the peeling state of the sample was evaluated according to the following criteria. The results are shown in Table 1. In Table 1, the laminate strength is shown in the upper part of the column for electrolytic solution resistance, and the evaluation is shown in the lower part. In addition, a case where delamination occurs and the laminate strength cannot be measured is referred to as “delamination”.
○: Laminate strength is 10 N / 15 mm or more (crosshead speed is 300 mm / min).
Δ: Laminate strength is 5 N / 15 mm or more and less than 10 N / 15 mm (crosshead speed is 300 mm / min).
X: Laminate strength is less than 5 N / 15 mm (crosshead speed is 300 mm / min).

"Examples 2-6, Comparative Examples 1-2"
Example 1 except that the materials used for forming the second inner layer side corrosion prevention treatment layer and the second adhesive layer and the aging temperature at the time of aging the laminate were changed as shown in Table 1. Similarly, an exterior material was prepared, and various measurements and evaluations were performed. The results are shown in Table 1. Further, FIG. 3 shows the infrared absorption spectrum of the second adhesive layer made of the adhesive composition used in Examples 2 and 5, and FIG. 3 shows the second adhesion made of the adhesive composition used in Examples 3 and 6. The infrared absorption spectrum of the adhesive layer is shown in FIG. 4, and the infrared absorption spectrum of the second adhesive layer made of the adhesive composition used in Comparative Examples 1 and 2 is shown in FIG.

As is clear from Table 1, the packaging material obtained in each example was excellent in resistance to electrolyte over a long period of time. In Examples 2 and 5, the second adhesive layer was formed using the same type of adhesive composition as in Examples 1 and 4, but the second adhesive layer had Y / X of Example 1. It was bigger than 4.
This is probably because the aging temperature was higher than in Examples 1 and 4 and the burette reaction proceeded more than in Examples 1 and 4.
On the other hand, the exterior material obtained in each comparative example in which the Y / X of the second adhesive layer is 0.38 has a storage period of 1 week in the electrolytic solution, and the laminate strength becomes insufficient. Delamination occurred and the electrolyte resistance was poor.

  ADVANTAGE OF THE INVENTION According to this invention, the exterior material for lithium batteries which can express the outstanding electrolyte solution resistance over a long period of time is obtained.

10 Lithium Battery Exterior Material 11 Base Material Layer 12 First Adhesive Layer 13 Corrosion Prevention Treatment Layer (Outer Layer Side Corrosion Prevention Treatment Layer)
14 Metal foil layer 15 Corrosion prevention treatment layer (inner layer side corrosion prevention treatment layer)
15a First inner layer side corrosion prevention treatment layer 15b Second inner layer side corrosion prevention treatment layer 16 Second adhesive layer 17 Sealant layer

Claims (4)

The base material layer, the first adhesive layer, the metal foil layer, the corrosion prevention treatment layer, the second adhesive layer, and the sealant layer are composed of a laminated body laminated in this order,
The second adhesive layer is composed of an adhesive composition containing an acid-modified polyolefin resin and a polyfunctional isocyanate compound. In the infrared absorption spectrum of the second adhesive layer, the CH _{3 has} a C—H bending vibration. An exterior material for a lithium battery, wherein the ratio (Y / X) of the derived absorption (X) to the absorption (Y) derived from N-H bending vibration of burette bond is 0.3 or less.   The packaging material for lithium batteries according to claim 1, wherein the polyfunctional isocyanate compound has an isocyanurate structure.   Acid-modified polyolefin resin is a homopolymer of propylene or a copolymer of propylene and ethylene, unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, unsaturated carboxylic acid ester, unsaturated carboxylic acid anhydride. The outer packaging material for a lithium battery according to claim 1 or 2, which is an acid-modified polyolefin resin grafted with at least one selected from the group consisting of esters of products.   The adhesive composition for a lithium battery according to any one of claims 1 to 3, wherein the adhesive composition further includes an organometallic catalyst containing at least one metal selected from the group consisting of tin, titanium, and zirconium.

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