JP7542092B2 - Non-aqueous battery exterior laminate - Google Patents

Description

The present invention relates to a non-aqueous battery exterior laminate used as an exterior material for secondary batteries such as lithium ion batteries, electric double layer capacitors, etc.

In recent years, with the growing concern about the global environment, the spread of electric vehicles and the effective use of natural energy sources such as wind power and solar power have become important issues. Accordingly, in these technical fields, secondary batteries such as lithium-ion batteries and electric double layer capacitors have been attracting attention as storage batteries for storing electrical energy.
As an exterior container for housing a lithium-ion battery used in an electric vehicle or the like, a container made of a laminate for battery exterior use, in which a metal foil and a resin layer are laminated, is used in order to reduce size and weight (see, for example, Patent Document 1).

A secondary battery can be produced by using an exterior container produced using the aforementioned laminate for battery exterior packaging, for example, as follows.
The laminate for battery exterior packaging is formed into a tray shape having a recess by drawing or the like to form a container body. A battery is housed in the recess of this container body. Next, a lid material made of the laminate for battery exterior packaging is placed on the container body, and the flange portion of the container body and the side edge portion of the lid material are heat sealed to obtain a secondary battery with a battery housed in an exterior container.

JP 2000-357494 A

In recent years, in applications such as storage batteries for electric vehicles, there is a demand for exterior containers for large batteries with larger external dimensions than before, and for exterior containers that can increase the internal volume by reducing the thickness of the battery exterior laminate. However, in the case of exterior containers for large batteries, it is necessary to form a container body with a deeper recess, which increases technical difficulties. For example, if the battery exterior laminate is deeply drawn, there is a risk of peeling between the metal foil and the resin layer, and damage (breakage, etc.) of the battery exterior laminate. In addition, if the thickness of the battery exterior laminate is reduced, there is a problem that mechanical strength such as puncture strength is reduced.
For this reason, there has been a demand for improving the mechanical strength of laminates for battery exteriors, reducing the occurrence of defects during drawing, and increasing the manufacturing yield of non-aqueous batteries.

The present invention was made in consideration of the above circumstances, and aims to provide a laminate for exterior packaging of non-aqueous batteries that can improve the production efficiency of non-aqueous batteries by increasing the mechanical strength of the laminate and preventing defects during drawing.

In order to solve the above problems, the present invention provides a laminated laminate comprising a base layer, a SUS foil, and a multi-layer sealant layer made of a polyolefin resin, the SUS foil and the sealant layer being bonded via a second adhesive layer made of a polyolefin resin containing a resin having an epoxy group or an oxazoline group, and a coating amount of 0.05 to 1.0 g/m containing a water-soluble resin and a metal fluoride compound is applied to at least the sealant layer side of the SUS foil. and a surface coating layer is formed by drying and curing the water-soluble paint of No. ² , the water-soluble resin being at least one selected from the group consisting of polyvinyl alcohol-based resins and polyvinyl ether-based resins, the amount of the water-soluble resin contained in the water-soluble paint is 0.1 to 1 mass %, the amount of the metal fluoride compound contained in the water-soluble paint is 0.1 to 2.5 mass %, the metal fluoride compound has an effect of crosslinking the water-soluble resin, and the sealant layer has, at the interface side with the SUS foil, a heat-adhesive polyolefin resin layer as the second adhesive layer, the heat-adhesive polyolefin resin layer containing at least one resin selected from the group consisting of an alloy material of a resin having an epoxy group and a polyolefin resin, and an alloy material of a resin having an oxazoline group and a polyolefin resin .

According to the present invention, a surface coating layer using a water-soluble paint containing a water-soluble resin and a metal fluoride compound is formed on at least the sealant layer side of the SUS foil, and the sealant layer has a heat-adhesive polyolefin resin layer, so that the sealant layer and the SUS foil can be bonded very firmly.
Therefore, when forming a recess by drawing, damage (such as tearing) of the nonaqueous battery exterior laminate can be prevented, and peeling between the sealant layer and the SUS foil can be prevented. Therefore, even when deep drawing is performed, the occurrence of defects when forming a battery exterior container can be reduced, the manufacturing yield of nonaqueous batteries can be improved, and production efficiency can be increased.
In addition, by increasing the adhesive strength between the sealant layer and the SUS foil, it is possible to prevent moisture from entering the battery exterior container from the outside, thereby suppressing deterioration of the electrolyte over time and extending the product life of the secondary battery.

In the present invention, the use of SUS foil can increase mechanical strength (tensile strength, etc.), and therefore damage (breakage, etc.) can be reduced when forming recesses by drawing. This prevents defective molding of battery exterior containers, improves battery production efficiency, and prevents deterioration of battery performance and fire caused by moisture infiltration and electrolyte leakage.
In addition, since SUS foil having high mechanical strength is used, the durability of the battery exterior container can be increased. Therefore, a structure (such as a cover case) for protecting the secondary battery during transportation or mounting of the secondary battery is not required or can be simplified. Therefore, packaging costs can be reduced and the packaging device can be made smaller. In addition, since SUS foil having high mechanical strength is used, the thickness of the battery exterior laminate can be reduced to increase the internal volume, and the volumetric efficiency of the battery can be improved.
Furthermore, since the SUS foil with the surface coating layer is used, deterioration due to corrosion is unlikely to occur even if moisture penetrates into the non-aqueous battery exterior container and causes the electrolyte to decompose and generate acid, so that leakage of the electrolyte caused by corrosion of the metal foil is prevented, and deterioration of battery performance and fire can be prevented.

1 is a schematic cross-sectional view showing a first embodiment of a nonaqueous battery exterior laminate according to the present invention. FIG. 2 is a perspective view showing an example of a secondary battery produced using the nonaqueous battery exterior laminate of FIG. 1 . 4 is a perspective view showing a process for manufacturing the secondary battery shown in the previous figure; FIG. FIG. 2 is a schematic cross-sectional view showing a second embodiment of a nonaqueous battery exterior laminate according to the present invention. 2 is a schematic cross-sectional view showing a first modified example of the battery exterior laminate shown in FIG. 1 . 1. FIG. 4 is a schematic cross-sectional view showing a second modified example of the battery exterior laminate shown in FIG. 1. FIG. 4 is a schematic cross-sectional view showing a third modified example of the battery exterior laminate shown in FIG. 1. FIG. 4 is a schematic cross-sectional view showing a fourth modified example of the battery exterior laminate shown in FIG.

Figure 1 shows a laminate 10 for battery exterior use, which is a first embodiment of the non-aqueous battery exterior laminate (hereinafter, sometimes simply referred to as the battery exterior laminate) according to the present invention. Also, Figure 2 shows a non-aqueous battery exterior container 20 (hereinafter, sometimes simply referred to as the battery exterior container 20) for a lithium ion battery manufactured using the laminate 10 for battery exterior use according to the present invention, and a secondary battery 40.

2 shows a perspective view of a secondary battery 40 using a battery exterior container 20, which is an example of a battery exterior container of the present invention. The secondary battery 40 is a battery exterior container 20 that contains a lithium ion battery 27.
The battery exterior container 20 is formed by stacking a container body 30 made of the battery exterior laminate 10, which is the first embodiment of the battery exterior laminate of the present invention, on a lid material 33 made of the battery exterior laminate 10, and heat sealing a peripheral portion 29. Reference numeral 28 denotes electrode leads connected to the positive and negative electrodes of a lithium ion battery 27.

1, a laminate 10 for battery exterior use according to the present invention has a structure in which a base layer 11, a SUS foil 12, and a sealant layer 13 are laminated in this order. In this specification, the SUS foil refers to a metal foil made of stainless steel.
The base material layer 11 and the SUS foil 12 are bonded to each other by a first adhesive layer 14 .
A printed layer 15 is formed on the SUS foil 12 side (the lower surface side in FIG. 1 ) of the base material layer 11. Surface coating layers 17 and 18 are formed on the sealant layer 13 side (the lower surface side in FIG. 1 ) and the base material layer 11 side (the upper surface side in FIG. 1 ) of the SUS foil 12, respectively.
Although this battery exterior laminate 10 has a printed layer 15, the printed layer 15 may be omitted.

Each layer will be described in detail below.
The base layer 11 is not particularly limited as long as it has sufficient mechanical strength, and examples of the base layer 11 that can be used include synthetic resin films made of polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); polyamide resins such as nylon (Ny); polyolefin resins such as oriented polypropylene (OPP); polyether ether ketone (PEEK), and polyphenylene sulfide (PPS);
The thickness of the base layer 11 may be, for example, 3 to 25 μm.

The substrate layer 11 may have a single layer structure or a multilayer structure. An example of a substrate layer 11 having a multilayer structure is a two-layer film in which a polyethylene terephthalate (PET) resin film is laminated on a biaxially oriented polyamide resin film (ONy). The substrate layer may have a multilayer structure in which three or more layers of film are laminated.

The base layer 11 is preferably made of a single-layer or multi-layer film using a heat-resistant resin film having a melting point of 200° C. or higher. Examples of such heat-resistant resin films include PET film, PEN film, PBT film, nylon film, PEEK film, and PPS film, and PET film is particularly preferable because of its cost advantage.
By using such a heat-resistant resin film, the heat resistance of the battery exterior laminate 10 can be increased, and the durability of the secondary battery 40 can be improved.

The SUS foil 12 is a metal foil made of stainless steel, and is made of, for example, austenitic, ferritic, martensitic, etc. Austenitic types include SUS304, 316, 301, etc., ferritic types include SUS430, etc., and martensitic types include SUS410, etc.
The SUS foil 12 has a higher mechanical strength, such as a tensile strength, than other metal foils such as aluminum foil, and therefore reduces the occurrence of pinholes when forming recesses by drawing, making it difficult for battery electrolyte to leak. In addition, the SUS foil 12 has a higher corrosion resistance than other metal foils, and therefore is less susceptible to deterioration due to corrosion.

The thickness of the SUS foil 12 can be, for example, 5 μm to 100 μm, and is preferably 5 μm to 50 μm.
By setting the thickness of the SUS foil 12 to 5 μm or more, it is possible to provide the laminate 10 for battery exterior with sufficient strength (such as piercing strength) and increase the durability of the secondary battery 40. Furthermore, by setting the thickness of the SUS foil 12 to 50 μm or less, it is possible to provide the laminate 10 for battery exterior with sufficient drawing processability.

The surface coating layers 17 and 18 are layers formed by drying and curing a water-soluble paint containing a water-soluble resin and a metal fluoride compound.
The thickness of each of the surface coating layers 17, 18 is 0.05 μm or more (preferably more than 0.2 μm). By making the thickness of the surface coating layers 17, 18 0.05 μm or more, sufficient corrosion resistance is imparted to the laminate for battery exterior 10, and the adhesive strength between the SUS foil 12 and the sealant layer 13, and the adhesive strength between the SUS foil 12 and the layer on the upper side thereof can be increased.
The thickness of the surface coating layers 17, 18 is set to 1.0 μm or less (preferably 0.5 μm or less). By setting the thickness of the surface coating layers 17, 18 to 1.0 μm or less, the adhesive strength between the SUS foil 12 and the sealant layer 13 can be increased and the material cost can be reduced.
The thickness of the surface coating layers 17, 18 is preferably in the range of more than 0.2 μm and not more than 0.5 μm.

As the water-soluble resin, it is preferable to use at least one of polyvinyl alcohol resins and polyvinyl ether resins.
The polyvinyl alcohol-based resin refers to at least one water-soluble resin selected from polyvinyl alcohol resins and modified polyvinyl alcohol resins.
The polyvinyl alcohol resin can be produced, for example, by saponifying a polymer of a vinyl ester monomer or a copolymer thereof.
Examples of the polymer or copolymer of a vinyl ester monomer include homopolymers or copolymers of vinyl ester monomers such as fatty acid vinyl esters, such as vinyl formate, vinyl acetate, and vinyl butyrate, and aromatic vinyl esters, such as vinyl benzoate, as well as copolymers of other monomers copolymerizable therewith.
Examples of other copolymerizable monomers include olefins such as ethylene and propylene, ether group-containing monomers such as alkyl vinyl ether, carbonyl group (ketone group)-containing monomers such as diacetone acrylamide, diacetone (meth)acrylate, allyl acetoacetate, and acetoacetic ester, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and maleic anhydride, vinyl halides such as vinyl chloride and vinylidene chloride, and unsaturated sulfonic acids.
The degree of saponification of the polyvinyl alcohol resin is usually preferably from 90 to 100 mol %, more preferably 95 mol % or more.

Examples of polyvinyl alcohol resins that can be used in the present invention include alkyl ether-modified polyvinyl alcohol resins, carbonyl-modified polyvinyl alcohol resins, acetoacetyl-modified polyvinyl alcohol resins, acetamide-modified polyvinyl alcohol resins, acrylonitrile-modified polyvinyl alcohol resins, carboxyl-modified polyvinyl alcohol resins, silicone-modified polyvinyl alcohol resins, ethylene-modified polyvinyl alcohol resins, etc. Among these, alkyl ether-modified polyvinyl alcohol resins, carbonyl-modified polyvinyl alcohol resins, carboxyl-modified polyvinyl alcohol resins, and acetoacetyl-modified polyvinyl alcohol resins are preferred.
Examples of commercially available polyvinyl alcohol resins include J-Poval DF-20 (product name) manufactured by Nippon Acetate Popal Co., Ltd. and Crossmer H Series (product name) manufactured by Nippon Carbide Industries Co., Ltd. The polyvinyl alcohol resin may be used alone or in combination of two or more kinds.

Examples of polyvinyl ether resins include homopolymers or copolymers of aliphatic vinyl ethers, such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, norbornyl vinyl ether, allyl vinyl ether, norbornenyl vinyl ether, 2-hydroxyethyl vinyl ether, and diethylene glycol monovinyl ether, as well as copolymers of other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl ether monomers include the same as the other monomers copolymerizable with the vinyl ester monomers described above.

In particular, polyvinyl ether-based resins containing, as monomers, aliphatic vinyl ethers having hydroxyl groups, such as 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 2-hydroxypropyl vinyl ether, and other monovinyl ethers of various glycols and polyhydric alcohols, are water-soluble and capable of undergoing a crosslinking reaction with the hydroxyl groups, and therefore can be suitably used in the present invention.
Since vinyl ether monomers can be used in the resin production (polymerization) process, these polyvinyl ether resins can be produced without going through a saponification treatment, unlike polyvinyl alcohol resins produced via vinyl ester polymers. Also usable are copolymers containing vinyl ester monomers and vinyl ether monomers, or vinyl alcohol-vinyl ether copolymers obtained by saponifying the copolymers. Also usable are mixtures of polyvinyl alcohol resins other than polyvinyl ether resins and polyvinyl ether resins.

As the water-soluble resin, either a polyvinyl alcohol-based resin or a polyvinyl ether-based resin may be used, or both may be used in combination.

The metal fluoride compound is preferably water-soluble since it must be mixed with the water-soluble resin.
Specific examples of the metal fluoride compound include chromium fluoride, iron fluoride, zirconium fluoride, titanium fluoride, hafnium fluoride, titanium hydrofluoric acid, and salts thereof.
The metal fluoride compound has the effect of improving the electrolyte resistance performance, that is, it can passivate the surface of the SUS foil 12 and increase the corrosion resistance against the electrolyte. The metal fluoride compound also has the effect of crosslinking the water-soluble resin.

The organic chelating agent contained in the water-soluble paint is an organic substance that can chemically bond with cations to form metal ion complexes.
The organic chelating agent bonds a metal compound (such as chromium oxide) derived from a metal fluoride compound with the water-soluble resin to increase the compressive strength of the surface coating layers 17, 18, so that even if the thickness of the surface coating layers 17, 18 is, for example, more than 0.2 μm and not more than 1.0 μm, the surface coating layers 17, 18 do not become brittle and crack or peel off. This makes it possible to increase the adhesive strength between the SUS foil 12 and the sealant layer 13, and between the SUS foil 12 and the layer above it.
In addition, the organic chelating agent has the effect of making the water-soluble resin water-resistant by chemically reacting with the water-soluble resin or the metal fluoride compound.

As the organic chelating agent, for example, an aminocarboxylic acid-based chelating agent, a phosphonic acid-based chelating agent, an oxycarboxylic acid-based, or a (poly)phosphoric acid-based chelating agent can be used.
Examples of aminocarboxylic acid chelating agents include nitrilotriacetic acid (NTA), hydroxyethyliminodiacetic acid (HIDA), ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), transcyclohexanediaminetetraacetic acid (CyDTA), 1,2-propanediaminetetraacetic acid (1,2-PDTA), 1,3-propanediaminetetraacetic acid (1,3-PDTA), 1,4-butanediaminetetraacetic acid (1,4-BDTA), 1,3-diamino- Examples of the diacetic acid include 2-hydroxypropanetetraacetic acid (DPTA-OH), glycol ether diamine tetraacetic acid (GEDTA), ethylenediamine orthohydroxyphenylacetic acid (EDHPA), SS-ethylenediamine disuccinic acid (SS-EDDS), ethylenediamine disuccinic acid (EDDS), β-alanine diacetic acid (ADA), methylglycine diacetic acid (MGDA), L-aspartic acid-N,N-diacetic acid (ASDA), L-glutamic acid-N,N-diacetic acid (GLDA), and N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBEDDA).
Examples of phosphonic acid chelating agents include N,N,N-trimethylenephosphonic acid (NTMP), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), ethylenediamine-N,N,N',N'-tetramethylenephosphonic acid (EDTMP), diethylenetriaminepentamethylenephosphonic acid (DTPMP), and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).
Examples of oxycarboxylic acid chelating agents include glycolic acid, citric acid, malic acid, gluconic acid, and glucoheptonic acid.
Examples of the (poly)phosphate chelating agent include metaphosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, pyrophosphoric acid, orthophosphoric acid, hexametaphosphoric acid, and salts thereof.
Generally available commercially available organic chelating agents include, for example, Chelest PD-4H (trade name) (PDTA) and Chelest PH-540 (trade name) (EDTMP) manufactured by Chelest Co., Ltd.

The amount of the water-soluble resin contained in the water-soluble paint is preferably 0.1 to 1% by mass.
By setting the amount of the water-soluble resin to 0.1 mass % or more, it is possible to increase the adhesive strength between the SUS foil 12 and the sealant layer 13. By setting the amount of the water-soluble resin to 1 mass % or less, it is possible to increase the adhesive strength between the SUS foil 12 and the sealant layer 13.

The amount of the metal fluoride compound contained in the water-soluble paint is preferably 0.1 to 2.5% by mass (preferably 0.8 to 2.5% by mass).
By setting the amount of the metal fluoride compound to 0.1 mass % or more, it is possible to improve the corrosion resistance of the SUS foil 12 against the electrolyte solution. Also, by setting the amount of the metal fluoride compound to 2.5 mass % or less, it is possible to prevent precipitation from occurring in the water-soluble paint and suppress unevenness in the coating film.

The amount of the organic chelating agent contained in the water-soluble paint is preferably 0.1 to 1% by mass (preferably 0.3 to 1% by mass).
By setting the amount of the metal fluoride compound to 0.1 mass % or more, it is possible to increase the compressive strength of the surface coating layers 17, 18 and suppress cracking or peeling of the surface coating layers 17, 18. Furthermore, by setting the amount of the organic chelating agent to 1 mass % or less, it is possible to impart sufficient strength to the surface coating layers 17, 18.

The surface coating layers 17 and 18 can be formed by applying the water-soluble paint to the SUS foil 12, and then heating and drying the paint in an oven or the like, followed by baking adhesion and crosslinking.

In the laminate 10 for battery exterior packaging shown in FIG. 1, surface coating layers 17, 18 are formed on both sides of the SUS foil 12, but the surface coating layer only needs to be formed on at least the sealant layer 13 side of the SUS foil 12. In other words, it is also possible to omit the surface coating layer 18 from the laminate 10 for battery exterior packaging shown in FIG. 1 (the laminate 60 for battery exterior packaging shown in FIG. 5).

In FIG. 1, the first adhesive layer 14 is not particularly limited as long as it can bond the base material layer 11 and the SUS foil 12, and can be formed from, for example, a urethane adhesive, an epoxy adhesive, or the like.
The first adhesive layer 14 can be formed by, for example, dry lamination.
The thickness of the first adhesive layer 14 can be, for example, 1 to 10 μm. By setting the thickness within this range, the base material layer 11 and the SUS foil 12 can be bonded with a sufficiently high adhesive strength to prevent delamination.

In the laminate 10 for battery exterior use according to the present invention, a coating layer 16 can be formed on the outer surface side (the upper surface side in FIG. 1 ) of the base material layer 11 .
The coating layer 16 (first coating layer) is formed from at least one resin selected from the group of resins consisting of urethane resin, acrylic resin, polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer resin, maleic anhydride modified polypropylene resin, polyester resin, epoxy resin, phenolic resin, phenoxy resin, fluororesin, cellulose ester resin, cellulose ether resin, polyamide resin, polyphenylene ether resin (PPE), polyphenylene sulfide resin (PPS), polyaryl ether resin (PAE), and polyether ether ketone resin (PEEK).
For the coating layer 16, one of the resins constituting the above resin group may be used alone, or two or more of them may be used in combination.
The coating layer 16 is preferably made of a material having excellent heat resistance.
In addition, the laminate for battery exterior packaging 10 shown in FIG. 1 has a coating layer 16 formed on the outer surface side of the base material layer 11, but the laminate for battery exterior packaging of the present invention may have a configuration without a coating layer (for example, the laminate for battery exterior packaging 70 shown in FIG. 6).

The coating layer 16 is desirably the outermost layer of the laminate 10 for battery exterior packaging.
The formation of the coating layer 16 enhances the insulation of the battery exterior laminate 10 and prevents damage to the surface of the battery exterior laminate 10. In addition, even if the battery exterior laminate 10 comes into contact with an electrolyte, changes in appearance (discoloration, etc.) can be prevented.

The coating layer 16 is preferably a thin, hardened layer formed by applying and drying a solvent-based paint prepared by dissolving the resin in an organic solvent.
Examples of organic solvents include hydrocarbon solvents such as toluene, xylene, normal hexane, cyclohexane, methylcyclohexane, normal heptane, tridecane, and tetradecane; ester solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate, cellosolve acetate, amyl acetate, normal propyl acetate, and isopropyl acetate; ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, DIBK (diisobutyl ketone), cyclohexanone, and DAA (diacetone alcohol); alcohol solvents such as methanol, ethanol, butanol, propanol, isopropyl alcohol, and normal propyl alcohol; and alcohol ether solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, dioxane, and ethylene glycol dimethyl ether. The organic solvent may be used alone or in combination of two or more of these.
Additives such as drying agents and stabilizers may be added to the solvent-based paint.

The solvent-based paint for forming the coating layer 16 can be applied by known printing methods such as offset printing, gravure printing, and screen printing.

The coating layer 16 can be colored by adding an achromatic or chromatic colorant to the solvent-based paint.
The color of the coating layer 16 can be selected arbitrarily. The coating layer 16 may be colored uniformly over the entire region (or a portion of the region), or multiple regions may be colored in different colors (or the same color) from each other.
The coating layer 16 may also be colored to display characters, figures, images, patterns, etc. These characters, etc. may represent, for example, a product name, a manufacturer, etc.
By coloring the coating layer 16, the design of the laminate for battery exterior use 10 can be improved.

The colorant may be a pigment or a dye.
Examples of pigments include organic pigments such as quinacridones, anthraquinones, perylenes, perinones, diketopyrrolopyrroles, isoindolinones, condensed azos, benzimidazolones, monoazos, insoluble azos, naphthols, flavanthrones, anthrapyrimidines, quinophthalones, pyranthrones, pyrazolones, thioindigo, anthanthrones, dioxazines, phthalocyanines, and indanthrones; metal complexes such as nickel dioxin yellow and copper azomethine yellow; metal oxides such as titanium oxide, iron oxide, and zinc oxide; metal salts such as barium sulfate and calcium carbonate; and inorganic pigments such as carbon black, aluminum, and mica.
Examples of the dye include azo-based, quinoline-based, stilbene-based, thiazole-based, indigoid-based, anthraquinone-based, and oxazine-based dyes.
The coating layer 16 may be colored by using a solvent-based paint containing ink. The ink is prepared by adding the colorant to an ink binder resin such as a urethane-based or acrylic-based ink binder resin.

The coating layer 16 may have a thickness of, for example, 0.1 μm or more. The coating layer 16 more preferably has a thickness of 2 μm or more.
By making the thickness of the coating layer 16 2 μm or more, it is possible to improve the insulation properties and to enhance the effect of preventing damage to the surface of the laminate for battery exterior 10. Furthermore, even if the laminate for battery exterior 10 comes into contact with an electrolyte, it is possible to reliably prevent changes in appearance (discoloration, etc.).
The thickness of the coating layer 16 can be, for example, 20 μm or less. By setting the thickness of the coating layer 16 in the range of 2 to 20 μm, the overall thickness of the battery exterior laminate 10 can be reduced.

The static friction coefficient (based on JIS K7125) of the surface of the coating layer 16 is preferably 0.3 or less.
By setting the static friction coefficient within this range, damage and deformation of the laminate 10 for battery exterior use during drawing can be reduced, making drawing easier.

The printing layer 15 (second coating layer) can have a similar structure to the coating layer 16 .
The printing layer 15 is formed from a material (at least one resin selected from the above-mentioned resin group) exemplified as a material usable for the coating layer 16. The constituent material of the printing layer 15 may be the same as the constituent material of the coating layer 16, or may be a material different from the constituent material of the coating layer 16.
Like the coating layer 16, the printed layer 15 is preferably a thin hardened layer formed by applying and drying a solvent-based paint prepared by dissolving the resin in an organic solvent.
The printed layer 15 and the first adhesive layer 14 can be colored by adding the colorant to the solvent-based paint, as in the coating layer 16. The colors of the printed layer 15 and the first adhesive layer 14 can be selected arbitrarily. The printed layer 15 and the first adhesive layer 14 may be colored uniformly over the entire region (or a portion of the region), or a plurality of regions may be colored in different colors (or the same color) from each other.
The printed layer 15 and the first adhesive layer 14 can also be colored to display characters, figures, images, patterns, etc. These characters, etc. may represent, for example, a product name, a manufacturer, etc. By coloring the printed layer 15 and the first adhesive layer 14, the design of the battery exterior laminate 10 can be improved.
The thickness of the printed layer 15 is, for example, 0.1 μm to 10 μm.
The printed layer 15 is formed by a known printing method such as offset printing, gravure printing, or screen printing.

The laminate 10 for battery exterior packaging in the example of FIG. 1 has a printed layer 15, but a configuration without the printed layer 15 (laminate 80 for battery exterior packaging shown in FIG. 7) is also possible. Also, a configuration in which the surface coating layer 18, coating layer 16, and printed layer 15 are omitted from the laminate 10 for battery exterior packaging in FIG. 1 (laminate 90 for battery exterior packaging shown in FIG. 8) is also possible.

The sealant layer 13 is made of a polyolefin resin and is the innermost layer in the secondary battery 40 (see FIG. 2).
The sealant layer 13 is placed on the innermost side because polyolefin resins have excellent resistance to the electrolyte of lithium ion batteries and good heat sealability, where heat sealability refers to the stability of the seal at high temperatures.
The polyolefin resin constituting the sealant layer 13 preferably contains primarily either a polypropylene resin or a polyethylene resin.

The sealant layer 13 has a multi-layer structure, and at the interface side with the SUS foil 12, has a layer made of a thermally adhesive polyolefin resin containing one or more types selected from the group of resins consisting of a maleic anhydride modified polyolefin resin (first polyolefin resin), an alloy material of a resin having an epoxy group and a polyolefin resin (second polyolefin resin), and an alloy material of a resin having an oxazoline group and a polyolefin resin (third polyolefin resin).
As the heat-adhesive polyolefin resin, one of the first to third polyolefin resins described above may be used alone, or two or more of them may be used in combination.

1, the sealant layer 13 may have a two-layer structure including a first layer 13a made of the heat-adhesive polyolefin resin and a second layer 13b made of a polypropylene resin. The first layer 13a is a layer on the interface side with the SUS foil 12.
The number of layers of the sealant layer 13 is not limited to the illustrated example, so long as the sealant layer 13 has a multi-layer structure having a layer made of the heat-adhesive polyolefin resin on the interface side with the SUS foil 12. For example, the sealant layer 13 may have a structure of three or more layers.

The first to third polyolefin resins described above are strongly bonded to the water-soluble resin contained in the surface coating layer 17, and therefore the bonding strength between the sealant layer 13 and the surface coating layer 17 can be increased.
When two or more of the first to third polyolefin resins described above are used, it is preferable to knead these polyolefin resins to form an alloy.

Maleic anhydride modified polyolefin resin is a polyolefin resin in which a portion of the molecule is modified with maleic anhydride.
Examples of commercially available maleic anhydride-modified polyolefin resins include those available under the trade name Admer manufactured by Mitsui Chemicals, Inc. (acid-modified polyethylenes include, for example, SF600, SF700, and NE060; acid-modified polypropylenes include, for example, QF551) and those available under the trade name Modic manufactured by Mitsubishi Chemical Corporation (acid-modified polyethylenes include, for example, M545; acid-modified polypropylenes include, for example, P555).

As the resin having an epoxy group, a polyolefin resin in which a part of the molecule has been modified with an epoxy group, or a resin obtained by melt-mixing an epoxy compound or a resin having an epoxy group with a polyolefin resin can be used.
A commercially available epoxy compound suitable for use in the present invention is, for example, "Epikote 1001" manufactured by Mitsubishi Chemical.
Furthermore, examples of resins having epoxy groups include "Modipar A4100" manufactured by NOF Corp.

As the resin having an oxazoline group, a resin in which a part of the molecule of a polyolefin resin has been modified with an oxazoline group, and a resin obtained by melt-mixing an oxazoline compound with a polyolefin resin can be used.
The oxazoline compound that can be used in the present invention is 2-isopropenyl-2-oxazoline, etc. A commercially available product suitable as the oxazoline compound is, for example, "Epocross WS-500" manufactured by Nippon Shokubai Co., Ltd.

The thickness of the sealant layer 13 is preferably 20 μm to 50 μm. By setting the thickness of the sealant layer 13 in this range, the pressure resistance strength of the heat-sealed portion can be increased and the infiltration of moisture into the battery exterior container 20 can be suppressed.
Furthermore, by setting the thickness of the sealant layer 13 within this range, the overall thickness of the laminate for battery exterior 10 can be reduced, and the secondary battery 40 can be made thinner.

The sealant layer 13 has the above-mentioned heat-adhesive polyolefin resin layer, and therefore can be bonded to the SUS foil 12 by thermal lamination.
The adhesive strength between the sealant layer 13 and the SUS foil 12 is preferably 5 N/15 mm or more when measured by the measurement method B (180 degree peeling) specified in JIS C6471.

The total thickness of the battery exterior laminate 10 can be, for example, 100 μm or less. This allows the secondary battery 40 to be made thinner.

The laminate 10 for battery exterior packaging preferably has a tensile elongation at break of 40% or more in both the MD and TD directions.
If the tensile elongation at break is within this range, the corner portions are sufficiently stretched when forming recesses by drawing, and therefore do not break.
The tensile elongation at break is determined in accordance with JIS K7127 at a tension speed of 50 mm/min.

Non-aqueous batteries in which the laminate for battery exteriors is used include secondary batteries such as lithium ion batteries and electric double layer capacitors that use an organic electrolyte as the electrolyte. Organic electrolytes generally use carbonate esters such as propylene carbonate (PC), diethyl carbonate (DEC), and ethylene carbonate as the medium, but are not limited to these.

Next, a method for manufacturing the secondary battery 40 shown in FIG. 2 will be described.
3(a), the laminate 10 for battery exterior packaging is formed into a tray shape having a recess 31 by drawing or the like to obtain a container body 30. The depth of the recess 31 can be, for example, 2 mm or more.
A lithium ion battery (lithium ion battery 27 in FIG. 2) is housed in recess 31 of container body 30 .
Next, as shown in FIG. 3(b), a lid material 33 made of the battery exterior laminate 10 is placed on top of the container body 30, and the flange portion 32 of the container body 30 and the peripheral portion 34 of the lid material 33 are heat-sealed to obtain the secondary battery 40 shown in FIG. 2.

In the laminate 10 for battery exterior use according to the present invention, a surface coating layer 17 is formed on at least the sealant layer 13 side of the SUS foil 12 using a water-soluble paint containing a water-soluble resin and a metal fluoride compound, and the sealant layer 13 has the heat-adhesive polyolefin resin layer, so that the sealant layer 13 and the SUS foil 12 can be bonded very firmly.
Therefore, when forming a recess by drawing, damage (such as tearing) of the laminate 10 for battery exterior can be reduced, and peeling between the sealant layer 13 and the SUS foil 12 can be prevented. Therefore, even when deep drawing is performed, the occurrence of defects during the formation of the battery exterior container 20 can be reduced, the manufacturing yield of the secondary battery 40 can be improved, and production efficiency can be increased.
Furthermore, in the battery exterior laminate 10, the adhesive strength between the sealant layer 13 and the SUS foil 12 is increased, thereby preventing moisture from penetrating from the outside into the battery exterior container 20. This makes it possible to suppress deterioration of the electrolyte over time and extend the product life of the secondary battery 40.

In the battery exterior laminate 10 according to the present invention, the mechanical strength (tensile strength, etc.) can be increased by using the SUS foil 12, and therefore damage (breakage, etc.) can be reduced when forming recesses by drawing. This prevents defective molding of the battery exterior container 20, improves the production efficiency of the secondary battery 40, and prevents deterioration of battery performance and fire caused by the ingress of moisture and leakage of electrolyte.
In addition, since the SUS foil 12 having high mechanical strength is used, the durability of the battery exterior container 20 can be increased. Therefore, a structure (such as a cover case) for protecting the secondary battery 40 during transportation or mounting of the secondary battery 40 is not required or can be simplified. Therefore, packaging costs can be reduced and the packaging device can be made smaller. In addition, since the SUS foil having high mechanical strength is used, the thickness of the battery exterior laminate can be reduced to increase the internal volume, and the volumetric efficiency of the battery can be improved.
Furthermore, since the SUS foil 12 on which the surface coating layer 17 is formed is used, deterioration due to corrosion is unlikely to occur even if the electrolyte decomposes and generates acid due to moisture that has penetrated into the battery exterior container 20. This prevents leakage of the electrolyte due to corrosion of the metal foil, and can prevent deterioration of battery performance and fire.

FIG. 4 shows a laminate for battery exterior packaging 50 which is a second embodiment of the laminate for battery exterior packaging of the present invention.
The laminate 50 for battery exterior according to the present invention has a second adhesive layer 19 made of a polyolefin resin containing a resin having an epoxy group or an oxazoline group provided between the SUS foil 12 and the sealant layer 13. The laminate 50 for battery exterior is different from the laminate 10 for battery exterior shown in FIG. 1 in that the SUS foil 12 and the sealant layer 13 are bonded together by this second adhesive layer 19.
In the laminate for battery exterior 50 , the second adhesive layer 19 can increase the adhesive strength between the SUS foil 12 and the sealant layer 13 .

(Measurement method)
Measurement method for adhesive strength between SUS foil and sealant layer: Measured by peel measurement method A (90° peel) specified in JIS C6471 "Test method for copper-clad laminates for flexible printed wiring boards."

(Measuring device)
Adhesive strength measuring device: Manufacturer: Shimadzu Corporation, Model: AUTOGRAPH AGS-100A tensile testing device

Example 1
A substrate layer made of a stretched polyethylene terephthalate (PET) resin film having a thickness of 12 μm was prepared.
This base layer and a SUS foil having a thickness of 30 μm were laminated by dry lamination via an adhesive layer (thickness 3 μm) made of a urethane adhesive.
A water-soluble paint was applied to both sides of the SUS foil (amount applied: 0.2 g/m ² ), and the resulting mixture was dried by heating in an oven at 200° C., baked, and crosslinked to form a surface coating layer.
The water-soluble paint is an aqueous solution containing 0.1 mass% polyvinyl alcohol resin (PVA resin) (manufactured by Nippon Carbide Industries Co., Ltd., product name: Crossmar H) (water-soluble resin), 0.8 mass% _CrF3 · _3H2O (metal fluoride compound), and 0.3 mass% PDTA (manufactured by Chelest Co., Ltd., product name: Chelest PD-4H) (organic chelating agent).

A sealant layer having a thickness of 30 μm was formed on the surface of the surface coating layer.
The sealant layer had a two-layer structure consisting of a first layer (thermally adhesive polyolefin resin layer) (thickness 15 μm) made of an alloy material of a resin having an epoxy group and a polyolefin resin, and a second layer (thickness 15 μm) made of a polypropylene resin. The first layer was the layer on the interface side with the SUS foil (see sealant layer 13 in FIG. 1).
As the "resin having epoxy groups", a polypropylene resin into which epoxy groups had been introduced by blending and compounding maleic anhydride modified polypropylene resin (manufactured by Mitsui Chemicals, Inc., product name: Admer Resin) with 1.5 mass% of a hydroxyl group-containing epoxy compound (manufactured by Mitsubishi Chemical, product name: Epicoat 1001) was used.
This "resin having epoxy groups" was mixed with a polypropylene resin (manufactured by Mitsui Chemicals, Inc., product name: Admer Resin) in a 1:1 (mass ratio) to obtain an alloy material.
This alloy material was co-extruded with polypropylene resin (manufactured by Mitsui Chemicals, Inc., product name: Admer Resin) to form a two-layer sealant layer having a first layer made of the alloy material and a second layer made of the polypropylene resin, thereby obtaining the laminate for battery exterior of Example 1.

A test piece was taken from this laminate for battery exterior, and this test piece was immersed in an electrolyte (a solution of ethylene carbonate (EC)/diethyl carbonate (DEC) 1:1 vol % with 1 mol/liter of _LiPF6 added) and held at a temperature of 80° C. for 24 hours.
Next, the test piece after the electrolyte immersion treatment was immersed in pure water for 30 minutes.
The adhesive strength between the SUS foil and the sealant layer was measured for the test pieces before and after immersion in the electrolyte, and after the water immersion treatment. The measurement results are shown in Table 1.

Example 2
A laminate for battery exterior was obtained in the same manner as in Example 1, except that the amount of polyvinyl alcohol-based resin (water-soluble resin) added was 0.2 mass %, and EDTMP-8H (manufactured by Chelest Co., Ltd., product name: Chelest PH-540) was used as the organic chelating agent.
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 3
A laminate for battery exteriors was obtained in the same manner as in Example 1, except that EDTMP·8H (manufactured by Chelest Co., Ltd., trade name: Chelest PH-540) was used as the organic chelating agent.
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 4
A laminate for battery exterior was obtained in the same manner as in Example 1, except that a polyvinyl alcohol-based resin (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., product name: DF-20) was used as the water-soluble resin and the amount added was 0.2 mass %.
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 5
A laminate for battery exterior was obtained in the same manner as in Example 1, except that a polyvinyl alcohol resin (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., product name: DF-20) was used as the water-soluble resin and its amount was 0.5 mass %, the amount of a metal fluoride compound was 1.5 mass %, and EDTMP-8H (manufactured by Chelest Co., Ltd., product name: Chelest PH-540) was used as the organic chelating agent and its amount was 0.5 mass %.
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 6
A laminate for battery exteriors was obtained in the same manner as in Example 1, except that a polyvinyl alcohol resin (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., product name: DF-20) was used as the water-soluble resin and its amount was 1.0 mass %, the amount of a metal fluoride compound was 2.5 mass %, and EDTMP-8H (manufactured by Chelest Co., Ltd., product name: Chelest PH-540) was used as the organic chelating agent and its amount was 1.0 mass %.
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

(Example 7)
A laminate for battery exterior was obtained in the same manner as in Example 1, except that the coating amount of the water-soluble paint was 0.05 g/ ^m2 .
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

(Example 8)
A laminate for battery exterior was obtained in the same manner as in Example 1, except that the amount of polyvinyl alcohol-based resin (water-soluble resin) added was 0.2 mass %, and EDTMP-8H (manufactured by Chelest Co., Ltd., product name: Chelest PH-540) was used as the organic chelating agent.
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 9
A laminate for battery exterior was obtained in the same manner as in Example 1, except that the sealant layer had a single layer structure (thickness 30 μm) made of maleic anhydride modified polypropylene resin (manufactured by Mitsui Chemicals, Inc., product name: Admer Resin).
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 10
A laminate for battery exterior packaging was obtained in the same manner as in Example 1, except that the sealant layer had a single layer structure (thickness: 30 μm) made of an alloy material of a resin having an oxazoline group and a polyolefin resin.
The resin having an oxazoline group was "Epocross RPS1005" manufactured by Nippon Shokubai Co., Ltd. The polyolefin resin was maleic anhydride modified polypropylene resin (manufactured by Mitsui Chemicals, Inc., product name: Admer Resin).
An alloy material was obtained by mixing a resin having an oxazoline group and a maleic anhydride modified polyolefin resin in a mass ratio of 2:98.
The adhesive strength of this laminate for battery exterior was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

(Comparative Example 1)
Except for not adding the water-soluble resin, the laminate for battery exterior production was obtained in the same manner as in Example 1, and the adhesive strength was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

(Comparative Example 2)
Except for not adding a metal fluoride compound and using EDTMP·8H (manufactured by Chelest Co., Ltd., product name: Chelest PH-540) as the organic chelating agent, a laminate for battery exterior was obtained in the same manner as in Example 1, and the adhesive strength was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 11
Except for changing the amount of polyvinyl alcohol-based resin (water-soluble resin) added to 0.2 mass % and adding no organic chelating agent, the laminate for battery exterior was obtained in the same manner as in Example 1, and the adhesive strength was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

(Comparative Example 4)
Except for changing the amount of the metal fluoride compound added to 3 mass %, the laminate for battery exterior production was obtained in the same manner as in Example 1, and the adhesive strength was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

(Comparative Example 5)
Except for changing the amount of polyvinyl alcohol-based resin (water-soluble resin) added to 0.2 mass % and using EDTMP-8H (manufactured by Chelest Co., Ltd., product name: Chelest PH-540) as the organic chelating agent, the laminate for battery exterior obtained in the same manner as in Example 1 was subjected to measurement of adhesive strength in the same manner as in Example 1. The measurement results are shown in Table 1.

The measurement results shown in Table 1 confirm that the laminates for battery exterior packaging of Examples 1 to 11 , in which a surface coating layer containing a water-soluble paint and a metal fluoride compound is formed, have a higher adhesive strength between the SUS foil and the sealant layer than the laminates for battery exterior packaging of Comparative Examples 1 and 2 , in which a surface coating layer lacking either the water-soluble paint or the metal fluoride compound is formed.
In addition, in the battery exterior laminate of Comparative Example 4, the concentration of the metal fluoride compound was high at 3 mass%, so when the organic chelate was added, the solubility decreased and the paint precipitated, resulting in unevenness in the coating film and making it brittle.
In addition, the laminate for battery exterior of Comparative Example 5 had a large coating amount of 1.2 g/m ² (calculated coating thickness of 1.2 μm), and therefore the adhesive strength between the SUS foil and the sealant layer was low.
Furthermore, if the density of the water-soluble paint containing the water-soluble resin and the metal fluoride compound is 1 g/ ^cm3 , the thickness of the surface coating layer obtained by drying and curing the water-soluble paint with an application amount of 0.2 g/ ^m2 is 0.2 μm. Therefore, the thickness of the surface coating layer in the laminate for battery exterior is 0.2 μm in Examples 1 to 6 , 9 to 11 and Comparative Examples 1 to 2 , and 4, 0.05 μm in Example 7, 1.0 μm in Example 8, and 1.2 μm in Comparative Example 5 .

In addition, although the measurement results are not shown in Table 1, the adhesive strength was measured in the same manner as in Example 1 for a laminate for battery exterior obtained in the same manner as in Example 1, except that the amount of polyvinyl alcohol-based resin (water-soluble resin) added was 0.05 mass % and EDTMP-8H (manufactured by Chelest Co., Ltd., product name: Chelest PH-540) was used as the organic chelating agent. As a result, the initial value, the value after immersion in the electrolyte, and the value after immersion in water after immersion in the electrolyte were 10 (N/15 mm), 4 (N/15 mm), and 2 (N/15 mm), respectively.
In addition, although the measurement results are not shown in Table 1, the adhesive strength was measured in the same manner as in Example 1 for a laminate for battery exterior obtained in the same manner as in Example 1, except that the amount of polyvinyl alcohol-based resin (water-soluble resin) added was 1.5 mass % and EDTMP-8H (manufactured by Chelest Co., Ltd., product name: Chelest PH-540) was used as the organic chelating agent. As a result, the initial value, the value after immersion in the electrolyte, and the value after immersion in water after immersion in the electrolyte were 8 (N/15 mm), 4 (N/15 mm), and 2 (N/15 mm), respectively.

10, 50... laminate for non-aqueous battery exterior, 11... substrate layer, 12... SUS foil, 13... sealant layer, 14... first adhesive layer, 15... printed layer, 16... coating layer, 17, 18... surface coating layer, 19... second adhesive layer, 20... exterior container for non-aqueous battery, 27... lithium ion battery, 40... secondary battery.

Claims (1)

A base layer, a SUS foil, and a multi-layer sealant layer made of a polyolefin resin are laminated in this order,
the SUS foil and the sealant layer are bonded via a second adhesive layer made of a polyolefin resin containing a resin having an epoxy group or an oxazoline group;
A surface coating layer is formed on at least the sealant layer side of the SUS foil by drying and curing a water-soluble paint containing a water-soluble resin and a metal fluoride compound in an amount of 0.05 to 1.0 g/ ^m2 ,
the water-soluble resin is at least one selected from the group consisting of polyvinyl alcohol-based resins and polyvinyl ether-based resins,
the amount of the water-soluble resin contained in the water-soluble paint is 0.1 to 1 mass %, and the amount of the metal fluoride compound contained in the water-soluble paint is 0.1 to 2.5 mass %,
the metal fluoride compound has an effect of crosslinking the water-soluble resin,
The sealant layer has, on the interface side with the SUS foil, a heat-adhesive polyolefin resin layer as the second adhesive layer, the heat-adhesive polyolefin resin layer containing one or more resins selected from the group consisting of an alloy material of a resin having an epoxy group and a polyolefin resin, and an alloy material of a resin having an oxazoline group and a polyolefin resin.

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