Packaging material for battery

Abstract

Provided is a packaging material for batteries that is effectively prevented from curling after molding. The present invention comprises a laminate in which at least a substrate layer, a metal layer, and a sealant layer are laminated in this order, The battery packaging material, wherein the thickness of the sealant layer is at least three times the thickness of the base material layer.

Description

Technical Field

[0001] The present invention relates to a battery packaging material with suppressed curl after forming.

Background Art

[0002] Conventionally, various types of batteries have been developed. In all batteries, a packaging material is an essential member for sealing battery elements such as electrodes and electrolytes. Conventionally, metal packaging materials have been widely used for battery packaging.

[0003] On the other hand, in recent years, with the improvement in performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., batteries are required to have various shapes, and are also required to be thinner and lighter. However, the conventionally widely used metal battery packaging materials have the disadvantages that it is difficult to follow the diversification of shapes and there is also a limit to weight reduction.

[0004] Therefore, in recent years, as a battery packaging material that can be easily processed into various shapes and can achieve thinning and weight reduction, a film-like laminate in which a base material / metal layer / sealant layer are sequentially laminated has been proposed (for example, see Patent Document 1). In such a battery packaging material, generally, a concave portion is formed by cold forming, battery elements such as electrodes and electrolytic solution are arranged in the space formed by the concave portion, and the sealant layers are heat-sealed to obtain a battery in which the battery elements are accommodated inside the battery packaging material.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, with the demand for miniaturization and thinning of batteries, there has been an increasing requirement for further thinning of the packaging materials for batteries. However, when the thickness of the battery packaging material becomes thin, the peripheral portion of the recess formed in the battery packaging material curls (bends), which may inhibit the accommodation of the battery element and the heat fusion of the sealant layer, thereby reducing the production efficiency of the battery. In particular, battery packaging materials used for large secondary batteries such as secondary batteries for automobiles have a problem that the influence of curl on the productivity of the battery is very large because of their large size. Under such circumstances, the main object of the present invention is to provide a technique for suppressing curl after molding in a battery packaging material comprising a laminate in which at least a base material layer, a metal layer, and a sealant layer are sequentially laminated.

Means for Solving the Problems

[0007] The present inventor has intensively studied to solve the above problems. As a result, in a battery packaging material comprising a laminate in which at least a base material layer, a metal layer, and a sealant layer are sequentially laminated, by setting the thickness of the sealant layer to be 3 times or more the thickness of the base material layer, even when the thickness of the battery packaging material becomes thin, for example, 160 μm or less, further 130 μm or less, and further 100 to 120 μm, it has been found that curl after molding can be effectively suppressed. The present invention has been completed by further studies based on these findings.

[0008] That is, the present invention provides a battery packaging material and a battery in the following aspects. Item 1. A battery packaging material comprising a laminate in which at least a base material layer, a metal layer, and a sealant layer are sequentially laminated, wherein the thickness of the sealant layer is 3 times or more the thickness of the base material layer. Item 2. A battery packaging material comprising a laminate in which at least a base material layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated, wherein the total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer. Item 3. The battery packaging material according to Item 1 or 2, wherein the thickness of the laminate is 160 μm or less. Item 4. The battery packaging material according to any one of Items 1 to 3, wherein the base material layer is formed of a stretched resin film and the sealant layer is formed of an unstretched resin film. Item 5. The battery packaging material according to any one of Items 1 to 4, wherein the base material layer is formed of at least one of a polyamide resin and a polyester resin. Item 6. The battery packaging material according to any one of Items 1 to 5, wherein the metal layer is formed of an aluminum foil. Item 7. The battery packaging material according to any one of Items 1 to 6, wherein a chemical conversion treatment is applied to at least one surface of the metal layer. Item 8. The battery packaging material according to any one of Items 1 to 7, which is a packaging material for a secondary battery. Item 9. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is housed in the battery packaging material according to any one of Items 1 to 8.

Advantages of the Invention

[0009] According to the battery packaging material of the present invention, in a battery packaging material comprising a laminate in which at least a base material layer, a metal layer, and a sealant layer are sequentially laminated, by making the thickness of the sealant layer 3 times or more the thickness of the base material layer, curling after molding can be effectively suppressed. Further, in the battery packaging material of the present invention, when an adhesive layer is laminated between the metal layer and the sealant layer, by making the total thickness of the adhesive layer and the sealant layer 3 times or more the thickness of the base material layer, curling after molding can be effectively suppressed. Furthermore, since the curling after molding is suppressed in the battery packaging material of the present invention, it is difficult to inhibit the housing of the battery element and the heat fusion of the sealant layer, and it can also contribute to an improvement in the productivity of the battery.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying out the Invention

[0011] The battery packaging material of the present invention is composed of a laminate in which at least a base material layer, a metal layer, and a sealant layer are sequentially laminated, and the thickness of the sealant layer is 3 times or more the thickness of the base material layer. Hereinafter, the battery packaging material of the present invention will be described in detail.

[0012] 1. Laminated structure of packaging material for battery As shown in FIG. 1, the battery packaging material 10 is composed of a laminate in which at least a base material layer 1, a metal layer 3, and a sealant layer 4 are sequentially laminated. In the battery packaging material of the present invention, the base material layer 1 is the outermost layer, and the sealant layer 4 is the innermost layer. That is, when assembling the battery, the sealant layers 4 located at the periphery of the battery element are heat-sealed to seal the battery element.

[0013] Further, as shown in FIG. 1 or FIG. 2, in the battery packaging material 10 of the present invention, an adhesive layer 2 may be provided between the base material layer 1 and the metal layer 3 as needed for the purpose of enhancing their adhesiveness. In the battery packaging material of the present invention, as shown in FIG. 2, an adhesive layer 5 may be provided between the metal layer 3 and the sealant layer 4 as needed for the purpose of enhancing their adhesiveness. Also, although not shown, a coating layer may be provided on the surface of the base material layer 1 (the surface opposite to the sealant layer 4).

[0014] In the present invention, when having the adhesive layer 5, the total thickness of the adhesive layer 5 and the sealant layer 4 only needs to be 3 times or more the thickness of the base material layer 1. Therefore, in this case, the thickness of the adhesive layer 5 alone or the sealant layer 4 alone may each be 3 times or more the thickness of the base material layer 1, or may be less than 3 times.

[0015] 2. Relationship between thicknesses of packaging material 10 for battery, base material layer 1, adhesive layer 5, and sealant layer 4 In the battery packaging material of the present invention, the thickness of the sealant layer 4 (the total thickness of the adhesive layer 5 and the sealant layer 4), which will be described later, is set to be 3 times or more the thickness of the base material layer 1, which will be described later. As described above, when the thickness of the battery packaging material becomes thin, the peripheral edge of the recess formed in the battery packaging material curls (bends), which may inhibit the accommodation of the battery element and the heat fusion of the sealant layer, and reduce the production efficiency of the battery. On the other hand, in the battery packaging material of the present invention, the thickness of the sealant layer 4 (the total thickness of the adhesive layer 5 and the sealant layer 4) is set to be 3 times or more greater than the thickness of the base material layer 1 constituting the battery packaging material. Thus, for example, even when the thickness of the battery packaging material is 160 μm or less, further 130 μm or less, and even further 100 - 120 μm, which is very thin, the curl after molding can be effectively suppressed.

[0016] Since the thicknesses of the base material layer 1 and the sealant layer 4 (the total thickness of the adhesive layer 5 and the sealant layer 4) have such a relationship, the details of the mechanism by which the curl after molding is effectively suppressed are not necessarily clear, but can be considered as follows, for example. That is, since the thickness of the sealant layer 4 (the total thickness of the adhesive layer 5 and the sealant layer 4) is set to be 3 times or more the thickness of the base material layer 1, at the time of molding, the influence of the shape change of the base material layer 1 on the entire battery packaging material becomes small, and it is considered that the curl (bending) of the battery packaging material accompanying the shape change (shrinkage) of the base material layer 1 around the recess formed by molding is suppressed.

[0017] In particular, battery packaging materials used for large secondary batteries such as secondary batteries for automobiles have a problem that the influence of curl on the productivity of the battery is very large because of their large size. When the battery packaging material of the present invention is used for large secondary batteries such as secondary batteries for automobiles, even when the thickness of the battery packaging material is, for example, 160 μm or less, further 130 μm or less, and even further 100 - 120 μm, which is very thin, the curl after molding can be effectively suppressed.

[0018] Further, the battery packaging material of the present invention is not limited to secondary batteries for automobiles, etc., and even when the thickness of the laminate constituting the battery packaging material is, for example, 100 μm or less, more preferably about 90 to 60 μm, the curl after molding is effectively suppressed. Therefore, the battery packaging material of the present invention can contribute to the improvement of the energy density of the battery while suppressing the decrease in battery productivity even by reducing the thickness.

[0019] In the present invention, the curl of the battery packaging material after molding can be evaluated by the method described in the examples (see FIGS. 3 and 4).

[0020] 3. Composition of each layer forming packaging material for battery [Base material layer 1] In the battery packaging material of the present invention, the base material layer 1 is the layer that forms the outermost layer. The material for forming the base material layer 1 is not particularly limited as long as it has insulation properties. Examples of the material for forming the base material layer 1 include resin films such as polyester resins, polyamide resins, epoxy resins, acrylic resins, fluororesins, polyurethane resins, silicone resins, phenol resins, and mixtures and copolymers thereof. Among these, polyester resins and polyamide resins are preferably used, and biaxially stretched polyester resins and biaxially stretched polyamide resins are more preferably used. Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolyester, polycarbonate, etc. Specific examples of the polyamide resin include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD6), etc.

[0021] In the case of a packaging material for a battery, when the resin film forming the base material layer 1 is a stretched resin film and the resin film forming the sealant layer described later is an unstretched film, it is easily affected by the orientation of the base material layer 1, and particularly has a problem that curling is likely to occur. However, in the packaging material for a battery of the present invention, since the thicknesses of the base material layer 1 and the sealant layer 4 are in the above relationship, even when the base material layer 1 and the sealant layer 4 are formed of such resin films, curling during molding can be effectively suppressed. In the present invention, the stretched resin film is obtained through a process of stretching at least one of the MD direction and the TD direction about 2 to 5 times during the production of the resin film, and the unstretched film refers to one that has not undergone such a process.

[0022] The base material layer 1 may be formed of a single layer of resin film, but may also be formed of two or more layers of resin films in order to improve pinhole resistance and insulation. When the base material layer 1 is formed of multiple layers of resin films, two or more resin films may be laminated via an adhesive component such as an adhesive or an adhesive resin. The type and amount of the adhesive component used are the same as those in the case of the adhesive layer 2 or the adhesive layer 5 described later. The method of laminating two or more layers of resin films is not particularly limited, and a known method can be adopted. For example, a dry lamination method, a sand lamination method, etc. can be mentioned, and preferably the dry lamination method can be mentioned. When laminating by the dry lamination method, it is preferable to use a urethane-based adhesive as the adhesive layer. At this time, the thickness of the adhesive layer is, for example, about 2 to 5 μm.

[0023] The thickness of the base material layer 1 is not particularly limited as long as it can exhibit the function as the base material layer and satisfy the above relationship with respect to the thickness of the sealant layer 4 (the total thickness of the adhesive layer 5 and the sealant layer 4). For example, it is about 10 to 50 μm, preferably about 15 to 25 μm.

[0024] [Adhesive layer 2] In the battery packaging material of the present invention, the adhesive layer 2 is a layer provided between the base material layer 1 and the metal layer 3 as necessary to firmly bond them.

[0025] The adhesive layer 2 is formed of an adhesive that can bond the base material layer 1 and the metal layer 3. The adhesive used for forming the adhesive layer 2 may be a two-component curing type adhesive or a one-component curing type adhesive. Furthermore, the adhesion mechanism of the adhesive used for forming the adhesive layer 2 is not particularly limited, and it may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a hot press type, etc.

[0026] Specific examples of the adhesive components that can be used for forming the adhesive layer 2 include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolymerized polyester; polyether adhesives; polyurethane adhesives; epoxy resins; phenolic resin resins; polyamide resins such as nylon 6, nylon 66, nylon 12, and copolymerized polyamide; polyolefin resins such as polyolefin, carboxylic acid-modified polyolefin, and metal-modified polyolefin, polyvinyl acetate resins; cellulose adhesives; (meth)acrylic resins; polyimide resins; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, a polyurethane adhesive is preferably mentioned.

[0027] The thickness of the adhesive layer 2 is not particularly limited as long as it exhibits the function as an adhesive layer. For example, it is about 1 to 10 μm, preferably about 2 to 5 μm.

[0028] [Metal layer 3] In the battery packaging material, the metal layer 3 functions as a barrier layer for preventing the intrusion of water vapor, oxygen, light, etc. into the battery in addition to improving the strength of the battery packaging material. Specific examples of the metal constituting the metal layer 3 include aluminum, stainless steel, titanium, etc., and preferably aluminum. The metal layer 3 can be formed by metal foil, metal vapor deposition, etc., and is preferably formed by metal foil, and more preferably formed by aluminum foil. From the viewpoint of preventing wrinkles and pinholes from occurring in the metal layer 3 during the manufacture of the battery packaging material, for example, it is more preferable to form it with a soft aluminum foil such as annealed aluminum (JIS A8021P-O, JIS A8079P-O).

[0029] The aluminum foil used as the metal layer 3 has a 0.2% proof stress when a tensile test is performed in the direction parallel to the MD direction and a 0.2% proof stress when a tensile test is performed in the direction parallel to the TD direction, both in the range of 55 to 140 N / mm 2 Preferably in the range of, more preferably in the range of 60 to 100 N / mm 2 The 0.2% proof stress is a value measured by the tensile test defined in JIS Z 2241.

[0030] The thickness of the metal layer 3 is not particularly limited as long as it exhibits the function as a metal layer. For example, it can be about 10 μm to 50 μm, preferably about 20 μm to 40 μm.

[0031] In addition, at least one surface of the metal layer 3, preferably both surfaces, is preferably subjected to chemical conversion treatment for stabilizing adhesion, preventing dissolution and corrosion, etc. Here, the chemical conversion treatment refers to a treatment for forming an acid-resistant film on the surface of the metal layer. Examples of the chemical conversion treatment include chromate treatment using chromic acid compounds such as chromic nitrate, chromic fluoride, chromic sulfate, chromic acetate, chromic oxalate, chromic pyrophosphate, acetylacetate chromate, chromic chloride, potassium sulfate chromate; phosphate chromate treatment using phosphate compounds such as sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid; chromate treatment using an aminophenol polymer having repeating units represented by the following general formulas (1) to (4), etc.

[0032]

Chem.

[0033]

Chem.

[0034]

Chem.

[0035]

Chem.

[0036] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. Also, R 1 and R 2 each independently represent the same or different hydroxyl group, alkyl group, or hydroxyalkyl group. In general formulas (1) to (4), X, R 1 and R 2Examples of the alkyl group represented by [alkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and tert-butyl group. Further, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by [hydroxyalkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxy group substituted, such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, and 4-hydroxybutyl group. In General Formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R 1 and R 2 may be the same or different from each other. In General Formulas (1) to (4), X is preferably a hydrogen atom, a hydroxyl group, or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by General Formulas (1) to (4) is preferably, for example, 500 to 1,000,000, and more preferably about 1,000 to 20,000.

[0037] Also, as a chemical conversion treatment method for imparting corrosion resistance to the metal layer 3, a coating obtained by dispersing fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or barium sulfate in phosphoric acid is applied, and a baking treatment is performed at 150 °C or higher to form a corrosion-resistant treatment layer on the surface of the metal layer 3. Further, a resin layer obtained by crosslinking a cationic polymer with a crosslinking agent may be further formed on the corrosion-resistant treatment layer. Here, examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine graft acrylic resin obtained by graft polymerizing a primary amine onto an acrylic main skeleton, polyallylamine or its derivative, and aminophenol. As these cationic polymers, only one type may be used, or two or more types may be used in combination. Also, examples of the crosslinking agent include a compound having at least one functional group selected from the group consisting of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent. As these crosslinking agents, only one type may be used, or two or more types may be used in combination.

[0038] For the chemical conversion treatment, only one type of chemical conversion treatment may be performed, or two or more types of chemical conversion treatments may be combined. Further, these chemical conversion treatments may be performed using a single compound alone, or two or more compounds may be used in combination. Among the chemical conversion treatments, chromic acid chromate treatment, chromate treatment combining a chromic acid compound, a phosphoric acid compound, and an aminated phenol polymer, etc. are preferable.

[0039] Regarding the amount of the acid-resistant film formed on the surface of the metal layer 3 in the chemical conversion treatment, there is no particular limitation. For example, in the case of performing the above chromate treatment, per 1 m² of the surface of the metal layer 3 2wherein the chromium compound is about 0.5 mg to about 50 mg in terms of chromium, preferably about 1.0 mg to about 40 mg; the phosphorus compound is about 0.5 mg to about 50 mg in terms of phosphorus, preferably about 1.0 mg to about 40 mg; and the aminated phenol polymer is contained in a proportion of about 1 mg to about 200 mg, preferably about 5.0 mg to 150 mg, which is desirable.

[0040] The chemical conversion treatment is carried out by applying a solution containing a compound used for forming an acid-resistant film onto the surface of the metal layer by means of a bar coating method, a roll coating method, a gravure coating method, a dipping method, etc., and then heating the metal layer so that the temperature of the metal layer reaches about 70°C to 200°C. Further, before subjecting the metal layer to the chemical conversion treatment, the metal layer may be preliminarily subjected to a degreasing treatment by means of an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, etc. By carrying out the degreasing treatment in this way, it becomes possible to carry out the chemical conversion treatment on the surface of the metal layer more efficiently.

[0041] [Sealing layer 4] In the battery packaging material of the present invention, the sealing layer 4 corresponds to the innermost layer and is a layer in which the sealing layers are heat-sealed to seal the battery element during battery assembly. In the battery packaging material of the present invention, when the adhesive layer 5 described later is laminated, the total thickness of the adhesive layer 5 and the sealing layer 4 may be three times or more the thickness of the base material layer 1, and the thickness of the sealing layer 4 alone may be three times or more the thickness of the base material layer 1, or less than three times. On the other hand, when the adhesive layer 5 described later is not laminated, the thickness of the sealing layer 4 alone is three times or more the thickness of the base material layer 1.

[0042] The resin component used for the sealing layer 4 is not particularly limited as long as it is heat-weldable. For example, polyolefin, cyclic polyolefin, carboxylic acid-modified polyolefin, and carboxylic acid-modified cyclic polyolefin can be mentioned.

[0043] Specific examples of the polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); terpolymers of ethylene-butene-propylene; and the like. Among these polyolefins, polyethylene and polypropylene are preferably mentioned.

[0044] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. Examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkenes are preferably mentioned, and norbornene is more preferably mentioned.

[0045] The carboxylic acid-modified polyolefin is a polymer obtained by modifying the polyolefin by block polymerization or graft polymerization with a carboxylic acid. Examples of the carboxylic acid used for the modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, and the like.

[0046] The carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an α,β-unsaturated carboxylic acid or its anhydride, or by block-polymerizing or graft-polymerizing an α,β-unsaturated carboxylic acid or its anhydride onto the cyclic polyolefin. The cyclic polyolefin to be carboxylic acid-modified is the same as described above. Further, the carboxylic acid used for the modification is the same as that used for the modification of the acid-modified cycloolefin copolymer.

[0047] Among these resin components, preferably a carboxylic acid-modified polyolefin; more preferably a carboxylic acid-modified polypropylene can be mentioned.

[0048] The sealant layer 4 may be formed of a single resin component alone, or may be formed of a blend polymer combining two or more resin components. Further, the sealant layer 4 may be composed of only one layer, but may be formed of two or more layers with the same or different resin components.

[0049] Also, the thickness of the sealant layer 4 is not particularly limited as long as it exhibits the function as a sealant layer and satisfies the above relationship with the thickness of the base material layer 1. For example, it is about 10 to 100 μm, preferably about 15 to 50 μm.

[0050] [Adhesive layer 5] In the battery packaging material of the present invention, the adhesive layer 5 is a layer provided between the metal layer 3 and the sealant layer 4 as necessary in order to firmly bond them. In the battery packaging material of the present invention, when the adhesive layer 5 is laminated, the total thickness of the adhesive layer 5 and the sealant layer 4 may be 3 times or more the thickness of the base material layer 1, and the thickness of the adhesive layer 5 alone may be 3 times or more the thickness of the base material layer 1, or may be less than 3 times.

[0051] The subsequent layer 5 is formed of an adhesive capable of bonding the metal layer 3 and the sealant layer 4. Regarding the adhesive used for forming the adhesive layer 5, the bonding mechanism, the types of adhesive components, etc. are the same as those in the case of the adhesive layer 2. As the adhesive component used for the adhesive layer 5, preferably a polyolefin-based resin, more preferably a carboxylic acid-modified polyolefin, and particularly preferably a carboxylic acid-modified polypropylene can be mentioned.

[0052] Regarding the thickness of the adhesive layer 5, there is no particular limitation as long as the function as an adhesive layer is exhibited. For example, it is about 2 to 50 μm, preferably about 15 to 30 μm.

[0053] [Coating layer] In the battery packaging material of the present invention, for the purpose of improving designability, electrolyte resistance, scratch resistance, formability, etc., a coating layer may be provided on the upper side of the base material layer 1 (the side opposite to the metal layer 3 of the base material layer 1) as necessary. The coating layer is the layer located on the outermost layer when the battery is assembled.

[0054] The coating layer can be formed of, for example, polyvinylidene chloride, polyester resin, urethane resin, acrylic resin, epoxy resin, etc. Among these, the coating layer is preferably formed of a two-component curable resin. Examples of the two-component curable resin for forming the coating layer include a two-component curable urethane resin, a two-component curable polyester resin, a two-component curable epoxy resin, etc. Further, a matting agent may be blended in the coating layer.

[0055] Examples of the matting agent include fine particles having a particle size of about 0.5 nm to 5 μm. The material of the matting agent is not particularly limited, and examples thereof include metals, metal oxides, inorganic substances, organic substances, etc. Further, the shape of the matting agent is also not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, balloon-like, etc. Specifically, as the matting agent, talc, silica, graphite, kaolin, montmorillonite, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high melting point nylon, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel, etc. may be mentioned. These matting agents may be used alone or in combination of two or more. Among these matting agents, from the viewpoints of dispersion stability, cost, etc., silica, barium sulfate, and titanium oxide are preferably mentioned. Further, various surface treatments such as insulation treatment and high dispersibility treatment may be applied to the surface of the matting agent.

[0056] The method for forming the coating layer is not particularly limited, and examples thereof include a method of applying a two-component curable resin for forming the coating layer on one surface of the base material layer 1. When the matting agent is blended, the matting agent may be added to the two-component curable resin, mixed, and then applied.

[0057] The thickness of the coating layer is not particularly limited as long as the above functions as the coating layer are exhibited, and examples thereof include about 0.5 to 10 μm, preferably about 1 to 5 μm.

[0058] 4. Manufacturing method of packaging material for battery The method for producing the battery packaging material of the present invention is not particularly limited as long as it can produce a laminate in which layers of predetermined compositions are laminated together. For example, the following method can be mentioned.

[0059] First, a laminate (hereinafter, sometimes referred to as "laminate A") is formed in which the base layer 1, the adhesive layer 2, and the metal layer 3 are laminated in this order. Specifically, the laminate A can be formed by a dry lamination method in which an adhesive used to form the adhesive layer 2 is applied to the base layer 1 or to the metal layer 3, the surface of which has been chemically treated as necessary, by a coating method such as extrusion, gravure coating, or roll coating, and then dried, and the metal layer 3 or the base layer 1 is laminated thereon, and the adhesive layer 2 is cured.

[0060] Next, the sealant layer 4 is laminated on the metal layer 3 of the laminate A. When the sealant layer 4 is directly laminated on the metal layer 3, the resin component constituting the sealant layer 4 may be applied to the metal layer 3 of the laminate A by a method such as gravure coating or roll coating. When an adhesive layer 5 is provided between the metal layer 3 and the sealant layer 4, for example, (1) the metal layer 3 of the laminate A may be laminated on the metal layer 3 by a method such as gravure coating or roll coating. (2) a method in which a laminate in which an adhesive layer 5 and a sealant layer 4 are laminated separately is formed, and this is laminated on the metal layer 3 of the laminate A by a thermal lamination method; (3) a method in which an adhesive for forming an adhesive layer 5 is laminated on the metal layer 3 of the laminate A by an extrusion method or a solution coating method, followed by drying at a high temperature and baking, and then a sealant layer 4 previously formed in a sheet form is laminated on this adhesive layer 5 by a thermal lamination method; and (4) a method in which a molten adhesive layer 5 is poured between the metal layer 3 of the laminate A and the sealant layer 4 previously formed in a sheet form, and the laminate A and the sealant layer 4 are bonded together via the adhesive layer 5 (sand lamination method).

[0061] When providing a coating layer, the coating layer is laminated on the surface of the base material layer 1 opposite to the metal layer 3. The coating layer can be formed, for example, by applying the above resin for forming the coating layer on the surface of the base material layer 1. Note that the order of the step of laminating the metal layer 3 on the surface of the base material layer 1 and the step of laminating the coating layer on the surface of the base material layer 1 is not particularly limited. For example, after forming a coating layer on the surface of the base material layer 1, the metal layer 3 may be formed on the surface of the base material layer 1 opposite to the coating layer.

[0062] As described above, a laminate composed of the base material layer 1 / adhesive layer 2 / optionally a metal layer 3 whose surface is passivated / optionally provided adhesive layer 5 / sealant layer 4 / optionally provided coating layer is formed. However, in order to strengthen the adhesiveness of the adhesive layer 2 and the optionally provided adhesive layer 5, it may be further subjected to heat treatment such as heat roll contact type, hot air type, near or far infrared type. Examples of the conditions for such heat treatment include 150 to 250 ° C for 1 to 5 minutes.

[0063] In the battery packaging material of the present invention, each layer constituting the laminate may be subjected to surface activation treatment such as corona treatment, blast treatment, oxidation treatment, ozone treatment, etc. as necessary to improve or stabilize film formability, lamination processing, final product secondary processing (pouching, embossing molding) suitability, etc.

[0064] 5. Use of packaging material for battery The battery packaging material of the present invention is used as a packaging material for sealing and accommodating battery elements such as a positive electrode, a negative electrode, and an electrolyte.

[0065] Specifically, a battery element including at least a positive electrode, a negative electrode, and an electrolyte is coated with the battery packaging material of the present invention in a state where metal terminals connected to each of the positive electrode and the negative electrode protrude outward, so that a flange portion (a region where the sealant layers contact each other) can be formed at the periphery of the battery element, and the sealant layers of the flange portion are heat-sealed and sealed, thereby providing a battery using the battery packaging material. When accommodating a battery element using the battery packaging material of the present invention, the sealant portion of the battery packaging material of the present invention is used so as to be on the inner side (the surface in contact with the battery element).

[0066] The battery packaging material of the present invention may be used for either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery to which the battery packaging material of the present invention is applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, lead storage batteries, nickel-hydrogen storage batteries, nickel-cadmium storage batteries, nickel-iron storage batteries, nickel-zinc storage batteries, silver oxide-zinc storage batteries, metal-air batteries, polyvalent cation batteries, capacitors, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are examples of suitable application targets for the battery packaging material of the present invention.

[0067] As described above, in particular, a battery packaging material used for a large secondary battery such as a secondary battery for automobiles has a problem that the influence of curl on the productivity of the battery is very large because of its large size. However, the battery packaging material of the present invention is particularly useful as a battery packaging material for secondary batteries for automobiles because the curl after molding is effectively suppressed.

Examples

[0068] Examples and comparative examples are shown below to explain the present invention in detail. However, the present invention is not limited to the examples.

[0069] Reference Examples 1, 2, Example 1, and Comparative Examples 1 - 8 <Manufacture of Battery Packaging Material> For a laminate in which a base material layer 1 / adhesive layer 2 / metal layer 3 are laminated in this order, an adhesive layer 5 and a sealant layer 4 were laminated by a thermal lamination method to produce a battery packaging material composed of a laminate in which a base material layer 1 / adhesive layer 2 / metal layer 3 / adhesive layer 5 / sealant layer 4 are laminated in this order. The details of the manufacturing conditions of the battery packaging material are as shown below.

[0070] First, an adhesive layer 2 was formed on one surface of the base material layer 1 to a thickness of 3 μm, and it was pressure-heated and bonded to the chemical conversion treatment surface of the metal layer 3 to produce a laminate in which the base material layer 1 / adhesive layer 2 / metal layer 3 were laminated in this order. Separately, an acid-modified polypropylene resin (an unsaturated carboxylic acid graft-modified random polypropylene graft-modified with an unsaturated carboxylic acid) constituting the adhesive layer 5 and a polypropylene (random copolymer) constituting the sealant layer 4 were co-extruded to produce a two-layer co-extruded film composed of the adhesive layer 5 and the sealant layer 4.

[0071] Next, the two-layer co-extruded film produced above was overlapped with the metal layer of the laminate composed of the base material layer 1 / adhesive layer 2 / metal layer 3 produced above so that the adhesive layer 5 of the two-layer co-extruded film was in contact, and thermal lamination was performed by heating to 120 °C for the metal layer 3, thereby obtaining a laminate in which the base material layer 1 / adhesive layer 2 / metal layer 3 / adhesive layer 5 / sealant layer 4 were laminated in this order. After the obtained laminate was once cooled, it was heated to 180 °C and heat-treated by holding that temperature for 1 minute, Reference Examples 1, 2, Example 1 and battery packaging materials of Comparative Examples 1-8 were obtained.

[0072] Reference Examples 1, 2, Example 1 The laminated structure and the thickness of each layer of the battery packaging materials produced in Comparative Examples 1-8 are as follows. The laminate of PET and nylon forming the base material layer 1 is obtained by bonding a PET film and a nylon film with an adhesive forming the adhesive layer 2. The thickness of the base material layer 1 does not include the thickness of the adhesive. ( Reference Example 1) PET (12 μm) / Adhesive layer (3 μm) / Nylon (15 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (40 μm) / Adhesive layer 5 (40 μm) / Sealant layer 4 (40 μm) ( Reference Example 2) PET (9 μm) / Adhesive layer (3 μm) / Nylon (12 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (30 μm) / Adhesive layer 5 (35 μm) / Sealant layer 4 (35 μm) (Example 1 ) PET (12 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (35 μm) / Adhesive layer 5 (30 μm) / Sealant layer 4 (30 μm) (Comparative Example 1) PET (12 μm) / Adhesive layer (3 μm) / Nylon (15 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (40 μm) / Adhesive layer 5 (30 μm) / Sealant layer 4 (30 μm) (Comparative Example 2) PET (9 μm) / Adhesive layer (3 μm) / Nylon (12 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (30 μm) / Adhesive layer 5 (30 μm) / Sealant layer 4 (30 μm) (Comparative Example 3) PET (12 μm) / Adhesive layer (3 μm) / Nylon (15 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (35 μm) / Adhesive layer 5 (30 μm) / Sealant layer 4 (30 μm) (Comparative Example 4) PET (12 μm) / Adhesive layer (3 μm) / Nylon (15 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (35 μm) / Adhesive layer 5 (22 μm) / Sealant layer 4 (23 μm) (Comparative Example 5) PET (12 μm) / Adhesive layer (3 μm) / Nylon (12 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (35 μm) / Adhesive layer 5 (30 μm) / Sealant layer 4 (30 μm) (Comparative Example 6) Nylon (25 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (40 μm) / Adhesive layer 5 (25 μm) / Sealant layer 4 (25 μm) (Comparative Example 7) Nylon (15 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (30 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (15 μm) (Comparative Example 8) Nylon (15 μm) / Adhesive layer 2 (3 μm) / Metal layer 3 (30 μm) / Adhesive layer 5 (15 μm) / Sealant layer 4 (10 μm)

[0073] <Evaluation of curl after forming> The battery packaging material obtained above was cut to produce strip pieces of 150×100 mm, which were used as test samples. Using a straight mold consisting of a rectangular male mold of 30×50 mm and a female mold with a clearance of 0.5 mm from this male mold, the above test sample was placed on the female mold such that the sealant layer 4 side was located on the male mold side, and the test sample was pressed with a holding pressure (surface pressure) of 0.1 MPa so that the forming depth was 6 mm, and cold forming (drawing one-step forming) was performed. The details of the position where the forming was performed are as shown in FIG. 3. As shown in FIG. 3, the forming was performed at a position where the shortest distance d between the rectangular forming portion M and the end portion P of the battery packaging material 10 was 25 mm. Next, the battery packaging material 10 after forming was placed on the horizontal plane 20 as shown in FIG. 4, and the maximum value t of the distance in the vertical direction y from the horizontal plane 20 to the end portion P was taken as the maximum height of the curled portion. The evaluation criteria for the curl after forming are as follows. The results are shown in Table 1. 〇: t = 0 mm or more and less than 10 mm, the curl is small, and the productivity is hardly reduced ×: t = 10 mm or more, the curl is large, and the reduction in productivity is large

[0074]

Table 1

[0075] As is clear from the results shown in Table 1, even when molding was performed under the severe condition of a molding depth of 6 mm, the total thickness of the adhesive layer 5 and the sealant layer 4 was three times or more the thickness of the base material layer 1. Reference Examples 1, 2, Example 1 In the battery packaging material of Reference Examples 1, 2, Example 1 , curling was effectively suppressed. On the other hand, in the battery packaging materials of Comparative Examples 1-8 in which the total thickness of the adhesive layer 5 and the sealant layer 4 was less than three times the thickness of the base material layer 1, when molding was performed at a molding depth of 6 mm, curling increased, Reference Examples 1, 2, Example 1 and it was inferior in terms of moldability compared to Reference Examples 1, 2, Example 1 .

Explanation of Reference Numerals

[0076] 1 Base material layer 2 Adhesive layer 3 Metal layer 4 Sealant layer 5 Adhesive layer 10 Packaging material for battery M Molding portion P End portion

Claims

1. It consists of a laminate in which at least a base material layer as the outermost layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated. The adhesive layer is a single layer and is directly adhered to the base material layer and the metal layer. The base material layer is formed only by a polyester film. The adhesive layer is formed by an acid-modified polyolefin. The adhesive layer has a thickness of 15 μm or more and 50 μm or less. The sealant layer has a thickness of 15 μm or more and 50 μm or less. The total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer. The metal layer includes at least one of aluminum foil and stainless steel foil, and is a packaging material for a battery.

2. It consists of a laminate in which at least a base material layer as the outermost layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated. The adhesive layer is a single layer and is directly adhered to the base material layer and the metal layer. The base material layer is formed only by a polyester film. The adhesive layer is formed by an acid-modified polyolefin. The adhesive layer has a thickness of 15 μm or more and 50 μm or less. The sealant layer has a thickness of 15 μm or more and 50 μm or less. The total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer. The sealant layer includes at least one selected from the group consisting of polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin, and is a packaging material for a battery.

3. It consists of a laminate in which at least a base material layer as the outermost layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated. The adhesive layer is a single layer and is directly adhered to the base material layer and the metal layer. The base material layer is formed only by a polyester film. The adhesive layer is formed of an acid-modified polyolefin. The adhesive layer has a thickness of 15 μm or more and 50 μm or less. The sealant layer has a thickness of 15 μm or more and 50 μm or less. The total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer. The sealant layer is formed of a blend polymer combining two or more resins, a battery packaging material.

4. It consists of at least a laminate in which a base material layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer, which are the outermost layers, are sequentially laminated. The adhesive layer is a single layer and is directly adhered to the base material layer and the metal layer. The base material layer is formed only by a polyester film. The adhesive layer is formed of an acid-modified polyolefin. The adhesive layer has a thickness of 15 μm or more and 50 μm or less. The sealant layer has a thickness of 15 μm or more and 50 μm or less. The total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer. The sealant layer is formed of two or more layers of the same or different resins, a battery packaging material.

5. It consists of at least a laminate in which a base material layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated. A single-layer coating layer constituting the outermost layer is laminated on the surface of the base material layer opposite to the adhesive layer side. The adhesive layer is a single layer and is directly adhered to the base material layer and the metal layer. The base material layer is formed only by a polyester film. The adhesive layer is formed of an acid-modified polyolefin, The adhesive layer has a thickness of 15 μm or more and 50 μm or less, The sealant layer has a thickness of 15 μm or more and 50 μm or less, The total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer, The metal layer includes at least one of an aluminum foil and a stainless steel foil, and is a packaging material for a battery.

6. It is composed of a laminate in which at least a base material layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated, A single-layer coating layer constituting the outermost layer is laminated on the surface of the base material layer opposite to the adhesive layer side, The adhesive layer is a single layer and directly adheres to the base material layer and the metal layer, The base material layer is formed only of a polyester film, The adhesive layer is formed of an acid-modified polyolefin, The adhesive layer has a thickness of 15 μm or more and 50 μm or less, The sealant layer has a thickness of 15 μm or more and 50 μm or less, The total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer, The sealant layer includes at least one selected from the group consisting of polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin, and is a packaging material for a battery.

7. It is composed of a laminate in which at least a base material layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated, A single-layer coating layer constituting the outermost layer is laminated on the surface of the base material layer opposite to the adhesive layer side, The adhesive layer is a single layer and directly adheres to the base material layer and the metal layer, The base material layer is formed only of a polyester film, The adhesive layer is formed of an acid-modified polyolefin, The adhesive layer has a thickness of 15 μm or more and 50 μm or less, The sealant layer has a thickness of 15 μm or more and 50 μm or less, The total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer, The sealant layer is formed of a blend polymer combining two or more resins, a battery packaging material.

8. It consists of a laminate in which at least a base material layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated, A single-layer coating layer constituting the outermost layer is laminated on the surface of the base material layer opposite to the adhesive layer side, The adhesive layer is a single layer and directly adheres to the base material layer and the metal layer, The base material layer is formed only of a polyester film, The adhesive layer is formed of an acid-modified polyolefin, The adhesive layer has a thickness of 15 μm or more and 50 μm or less, The sealant layer has a thickness of 15 μm or more and 50 μm or less, The total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer, The sealant layer is formed of two or more layers of the same or different resins, a battery packaging material.

9. The battery packaging material according to any one of claims 1 to 8, wherein the thickness of the laminate is 160 μm or less.

10. The battery packaging material according to any one of claims 1 to 9, wherein the base material layer is formed of a stretched polyester film and the sealant layer is formed of an unstretched resin film.

11. The battery packaging material according to any one of claims 1 to 10, wherein the base material layer is formed of at least one of polyethylene terephthalate and polybutylene terephthalate.

12. The battery packaging material according to any one of claims 1 to 11, wherein the metal layer is formed of an aluminum foil.

13. The battery packaging material according to any one of claims 1 to 12, wherein a chemical conversion treatment is applied to at least one surface of the metal layer.

14. The battery packaging material according to any one of claims 1 to 13, which is a packaging material for a secondary battery.

15. A battery, wherein a battery element including at least a positive electrode, a negative electrode, and an electrolyte is housed in the battery packaging material according to any one of claims 1 to 14.

16. A method for manufacturing a battery packaging material, comprising a step of obtaining a laminate in which at least an outermost base material layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated, wherein the adhesive layer is a single layer and is directly adhered to the base material layer and the metal layer, wherein the base material layer is formed only of a polyester film, wherein the adhesive layer is formed of an acid-modified polyolefin, wherein the adhesive layer has a thickness of 15 μm or more and 50 μm or less, wherein the sealant layer has a thickness of 15 μm or more and 50 μm or less, wherein the total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer. A method for manufacturing a battery packaging material.

17. A method for manufacturing a battery packaging material, comprising a step of obtaining a laminate in which at least a base material layer, an adhesive layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated, A single-layer coating layer constituting the outermost layer is laminated on the surface of the base material layer opposite to the adhesive layer side. The adhesive layer is a single layer and is directly adhered to the base material layer and the metal layer. The base material layer is formed only of a polyester film. The adhesive layer is formed of an acid-modified polyolefin. The adhesive layer has a thickness of 15 μm or more and 50 μm or less. The sealant layer has a thickness of 15 μm or more and 50 μm or less. A method for manufacturing a battery packaging material, wherein the total thickness of the adhesive layer and the sealant layer is 3 times or more the thickness of the base material layer.

18. The adhesive layer and the sealant layer are formed by a coextrusion lamination method, a thermal lamination method, a sandwich lamination method, or a method of laminating an adhesive for forming the adhesive layer on a metal layer and laminating the sealant layer previously formed in a sheet shape on the adhesive layer. The method for manufacturing a battery packaging material according to claim 16 or 17.

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