JP6879321B2 - Battery packaging material - Google Patents

Description

The present invention relates to a packaging material for a battery in which curling after molding is suppressed.

Conventionally, various types of batteries have been developed, but in all batteries, a packaging material is an indispensable member for sealing a battery element such as an electrode or an electrolyte. Conventionally, metal packaging materials have been widely used for battery packaging.

On the other hand, in recent years, along with the high performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., batteries are required to have various shapes, and are required to be thinner and lighter. However, the metal packaging material for batteries, which has been widely used in the past, has a drawback that it is difficult to keep up with the diversification of shapes and there is a limit to weight reduction.

Therefore, in recent years, as a packaging material for batteries that can be easily processed into various shapes and can be made thinner and lighter, a film-like laminate in which a base material / metal layer / sealant layer is sequentially laminated has been proposed. (See, for example, Patent Document 1). In such battery packaging materials, recesses are generally formed by cold molding, and battery elements such as electrodes and electrolytes are arranged in the space formed by the recesses to heat-seal the sealant layers to each other. By doing so, a battery in which the battery element is housed inside the packaging material for the battery can be obtained.

Japanese Unexamined Patent Publication No. 2008-287971

In recent years, with the demand for smaller and thinner batteries, further thinning of the packaging material for batteries is required. However, when the thickness of the battery packaging material becomes thin, the peripheral edge of the recess formed in the battery packaging material is curled (curved), which hinders the accommodation of the battery element and the heat fusion of the sealant layer, so that the battery It may reduce production efficiency. 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 batteries is very large because of their large size. ..
Under such circumstances, a main object of the present invention is to provide a technique for suppressing curl after molding, at least in a battery packaging material composed of a laminate in which a base material layer, a metal layer, and a sealant layer are sequentially laminated. To provide.

The present inventor has made diligent studies to solve the above-mentioned problems. As a result, at least in a battery packaging material composed of a laminate in which a base material layer, a metal layer, and a sealant layer are sequentially laminated, the thickness of the sealant layer is set to three times or more the thickness of the base material layer. It has been found that curl after molding can be effectively suppressed even when the thickness of the packaging material for a battery is reduced to, for example, 160 μm or less, further 130 μm or less, and further 100 to 120 μm. The present invention has been completed by further studies based on these findings.

That is, the present invention provides a battery packaging material and a battery according to the following aspects.
Item 1. At least, it is composed of a laminate in which a base material layer, a metal layer, and a sealant layer are sequentially laminated.
A packaging material for a battery in which the thickness of the sealant layer is three times or more the thickness of the base material layer.
Item 2. At least, it is composed of a laminate in which a base material layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated.
A packaging material for a battery in which the total thickness of the adhesive layer and the sealant layer is three times or more the thickness of the base material layer.
Item 3. Item 2. The packaging material for a battery according to Item 1 or 2, wherein the thickness of the laminate is 160 μm or less.
Item 4. Item 3. The packaging material for a battery 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. Item 2. The packaging material for a battery 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. Item 2. The battery packaging material according to any one of Items 1 to 5, wherein the metal layer is formed of aluminum foil.
Item 7. Item 2. The packaging material for a battery according to any one of Items 1 to 6, wherein at least one surface of the metal layer is subjected to chemical conversion treatment.
Item 8. Item 2. 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.

According to the battery packaging material of the present invention, at least in a battery packaging material composed of a laminate in which a base material layer, a metal layer, and a sealant layer are sequentially laminated, the thickness of the sealant layer is set to 3 as the thickness of the base material layer. By doubling or more, 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, the total thickness of the adhesive layer and the sealant layer is three times the thickness of the base material layer. By doing so, curl after molding can be effectively suppressed. Further, since the packaging material for a battery of the present invention suppresses curling after molding, it is unlikely to hinder the accommodation of the battery element and the heat fusion of the sealant layer, and can contribute to the improvement of battery productivity. it can.

It is a figure which shows an example of the cross-sectional structure of the packaging material for a battery of this invention. It is a figure which shows an example of the cross-sectional structure of the packaging material for a battery of this invention. It is a schematic diagram for demonstrating the evaluation method of curl. It is a schematic diagram for demonstrating the evaluation method of curl.

The packaging material for a battery of the present invention is composed of a laminate in which a base material layer, a metal layer, and a sealant layer are sequentially laminated, and the thickness of the sealant layer is at least three times the thickness of the base material layer. It is a feature. Hereinafter, the packaging material for batteries of the present invention will be described in detail.

1. 1. Laminated structure of battery packaging material As shown in FIG. 1, the battery packaging material 10 is composed of at least a laminate in which a base material layer 1, a metal layer 3, and a sealant layer 4 are sequentially laminated. In the packaging material for batteries 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 the battery is assembled, the sealant layers 4 located on the periphery of the battery element are heat-welded to each other to seal the battery element, thereby sealing the battery element.

Further, as shown in FIG. 1 or 2, the battery packaging material 10 of the present invention has an adhesive layer between the base material layer 1 and the metal layer 3 for the purpose of enhancing the adhesiveness thereof, if necessary. 2 may be provided. In the battery packaging material of the present invention, as shown in FIG. 2, even if an adhesive layer 5 is provided between the metal layer 3 and the sealant layer 4 for the purpose of enhancing their adhesiveness, if necessary. Good. Further, 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).

In the present invention, when the adhesive layer 5 is provided, the total thickness of the adhesive layer 5 and the sealant layer 4 may be three 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 be three times or more or less than three times the thickness of the base material layer 1, respectively.

2. Relationship between the thickness of the battery packaging material 10, the base material layer 1, the adhesive layer 5, and the sealant layer 4 In the battery packaging material of the present invention, the thickness of the sealant layer 4 described later (the total of the adhesive layer 5 and the sealant layer 4). The thickness) is set to be three times or more the thickness of the base material layer 1 described later. As described above, when the thickness of the battery packaging material is reduced, the peripheral edge of the recess formed in the battery packaging material is curled, which hinders the accommodation of the battery element and the heat fusion of the sealant layer. It may 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 larger than the thickness of the base material layer 1 constituting the battery packaging material. ) Is set to be 3 times or more larger, for example, even when the thickness of the battery packaging material is 160 μm or less, 130 μm or less, and even 100 to 120 μm, which is very thin, curl after molding. Can be effectively suppressed.

By having such a relationship between 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), curling after molding is effectively suppressed. The details are not always clear, but can be thought of 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 three times or more the thickness of the base material layer 1, the shape of the base material layer 1 changes during molding. It is considered that the influence of the coating material on the entire battery packaging material is reduced, and the curl (curving) of the battery packaging material due to the shape change (shrinkage) of the base material layer 1 around the recess formed by molding is suppressed. ..

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 batteries is very large because of their large size. .. When the packaging material for a battery of the present invention is used for a large secondary battery such as a secondary battery for an automobile, the thickness of the packaging material for the battery is, for example, 160 μm or less, further 130 μm or less, and further. Even when it is very thin, 100 to 120 μm, curl after molding can be effectively suppressed.

Further, the packaging material for a battery of the present invention is not limited to a secondary battery for an automobile, and even when the thickness of the laminate constituting the packaging material for a battery is as thin as, for example, 100 μm or less, and further 90 to 60 μm. Curling 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 the productivity of the battery by reducing the thickness.

In the present invention, the curl of the packaging material for a battery after molding can be evaluated by the method described in Examples (see FIGS. 3 and 4).

3. 3. Composition of each layer forming the packaging material for batteries [Base material layer 1]
In the packaging material for batteries of the present invention, the base material layer 1 is a layer forming the outermost layer. The material forming the base material layer 1 is not particularly limited as long as it has an insulating property. Examples of the material forming the base material layer 1 include polyester resin, polyamide resin, epoxy resin, acrylic resin, fluororesin, polyurethane resin, silicon resin, phenol resin, and resin films such as mixtures and copolymers thereof. Can be mentioned. Among these, polyester resin and polyamide resin are preferable, and biaxially stretched polyester resin and biaxially stretched polyamide resin are more preferable. Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. Specific examples of the polyamide resin include nylon 6, nylon 6, 6, a copolymer of nylon 6 and nylon 6, 6, nylon 6, 10, polymethoxylylen adipamide (MXD6), and the like. Be done.

In the packaging material for batteries, 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, the influence of the orientation of the base material layer 1 is affected. It has a problem that it is easily received and curls are particularly likely to occur. However, in the packaging material for a battery of the present invention, the thickness of the base material layer 1 and the sealant layer 4 has the above relationship, so that the base material layer is easily received. Even when 1 and the sealant layer 4 are formed of such a resin film, curling during molding can be effectively suppressed. In the present invention, the stretched resin film is obtained by undergoing a step of stretching about 2 to 5 times in at least one of the MD direction and the TD direction at the time of manufacturing the resin film, and is a non-stretched film. Refers to a product that has not undergone such a process.

The base material layer 1 may be formed of one layer of resin film, but may be formed of two or more layers of resin film in order to improve pinhole resistance and insulating property. When the base material layer 1 is formed of a multilayer resin film, two or more resin films may be laminated via an adhesive component such as an adhesive or an adhesive resin, and the type and amount of the adhesive component used may be used. The same applies to 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. Examples thereof include a dry lamination method and a sand lamination method, and a dry lamination method is preferable. 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.

The thickness of the base material layer 1 is not particularly limited as long as the above relationship with respect to the thickness of the sealant layer 4 (total thickness of the adhesive layer 5 and the sealant layer 4) can be satisfied while exhibiting the function as the base material layer. For example, about 10 to 50 μm, preferably about 15 to 25 μm can be mentioned.

[Adhesive layer 2]
In the packaging material for batteries 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 in order to firmly bond the base material layer 1 and the metal layer 3.

The adhesive layer 2 is formed by an adhesive capable of adhering the base material layer 1 and the metal layer 3 to each other. The adhesive used to form the adhesive layer 2 may be a two-component curable adhesive or a one-component curable adhesive. Further, the adhesive mechanism used for forming the adhesive layer 2 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a thermal pressure type and the like.

Specific examples of the adhesive component that can be used to form the adhesive layer 2 include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolymerized polyester; Ether-based adhesives; Polyethylene-based adhesives; Epoxy resins; Phenolic resin-based resins; Polyamide-based resins such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; Polyethylenes such as polyolefins, carboxylic acid-modified polyolefins, and metal-modified polyolefins. Resins, polyvinyl acetate resins; cellulose adhesives; (meth) acrylic resins; polyimide resins; urea resins, melamine resins and other amino resins; chloroprene rubbers, nitrile rubbers, styrene-butadiene rubbers and other rubbers; silicones Examples include based resins. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, a polyurethane-based adhesive is preferable.

The thickness of the adhesive layer 2 is not particularly limited as long as it functions as an adhesive layer, and examples thereof include about 1 to 10 μm, preferably about 2 to 5 μm.

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

The aluminum foil used as the metal layer 3 has a 0.2% proof stress when a tensile test is conducted in a parallel direction with respect to the MD direction and a 0.2% proof stress when a tensile test is conducted in a parallel direction with respect to the TD direction. and strength are both preferably in the range of 55~140N / mm ^2, more preferably in the range of 60~100N / mm ^2. The 0.2% proof stress is a value measured by a tensile test specified in JIS Z 2241.

The thickness of the metal layer 3 is not particularly limited as long as it functions as a metal layer, but can be, for example, about 10 μm to 50 μm, preferably about 20 μm to 40 μm.

Further, it is preferable that at least one surface, preferably both sides, of the metal layer 3 is subjected to chemical conversion treatment in order to stabilize adhesion, prevent dissolution and corrosion, and the like. Here, the chemical conversion treatment refers to a treatment for forming an acid-resistant film on the surface of a metal layer. As the chemical conversion treatment, for example, chromium chromate using a chromium acid compound such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium bicarbonate, acetylacetate chromate, chromium chloride, and chromium potassium sulfate is used. Treatment; Chromic acid chromate treatment using a phosphoric acid compound such as sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphate; aminoated phenol having a repeating unit represented by the following general formulas (1) to (4). Chromate treatment using a polymer and the like can be mentioned.

In the 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. In addition, R ¹ and R ² represent a hydroxyl group, an alkyl group, or a hydroxyalkyl group, respectively, which are the same or different. In the general formulas (1) to (4) ^{, examples of the alkyl group represented by X, R 1} and R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and an isobutyl group. Examples thereof include a linear or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group. Examples of the hydroxyalkyl groups represented by X, R ¹ and R ² include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group and 3-. A linear or branched chain having 1 to 4 carbon atoms in which one hydroxy group such as a hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, or a 4-hydroxybutyl group is substituted. Alkyl groups can be mentioned. In the general formulas (1) to (4), the ^{alkyl group and the hydroxyalkyl group represented by X, R 1} and R ² may be the same or different, respectively. In the 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 amination phenol polymer having the repeating unit represented by the general formulas (1) to (4) is preferably, for example, 5 to 1,000,000, and more preferably about 1,000 to 20,000. preferable.

Further, as a chemical conversion treatment method for imparting corrosion resistance to the metal layer 3, a material obtained by dispersing metal oxides such as aluminum oxide, titanium oxide, cerium oxide and tin oxide and fine particles of barium sulfate is coated in phosphoric acid. A method of forming a corrosion-resistant treatment layer on the surface of the metal layer 3 by performing a baking treatment at 150 ° C. or higher can be mentioned. Further, a resin layer obtained by cross-linking a cationic polymer with a cross-linking 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 on an acrylic main skeleton, and polyallylamine. Alternatively, a derivative thereof, aminophenol and the like can be mentioned. As these cationic polymers, only one kind may be used, or two or more kinds may be used in combination. Examples of the cross-linking 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, a silane coupling agent, and the like. As these cross-linking agents, only one type may be used, or two or more types may be used in combination.

As 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 carried out by using one kind of compound alone, or by using two or more kinds of compounds in combination. Among the chemical conversion treatments, chromate chromate treatment and chromate treatment in which a chromic acid compound, a phosphoric acid compound, and an amination phenol polymer are combined are preferable.

The amount of the acid-resistant film formed on the surface of the metal layer 3 in the chemical conversion treatment is not particularly limited, but for example, in the case of performing the above chromate treatment, the chromic acid compound is contained per ^{1 m 2 of the surface of the metal layer 3.} 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 weight of aminoated phenol. It is desirable that the coalescence is contained in a proportion of about 1 mg to about 200 mg, preferably about 5.0 mg to 150 mg.

In the chemical conversion treatment, a solution containing a compound used for forming an acid-resistant film is applied to the surface of the metal layer by a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like, and then the temperature of the metal layer is 70. It is carried out by heating to about ° C. to 200 ° C. Further, before the metal layer is subjected to the chemical conversion treatment, the metal layer may be subjected to a degreasing treatment by an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method or the like in advance. By performing the degreasing treatment in this way, it becomes possible to more efficiently perform the chemical conversion treatment on the surface of the metal layer.

[Sealant layer 4]
In the battery packaging material of the present invention, the sealant layer 4 corresponds to the innermost layer, and is a layer in which the sealant layers are heat-welded to each other during battery assembly to seal the battery element. 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 sealant layer 4 is three times or more the thickness of the base material layer 1. Often, the thickness of the sealant 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 sealant layer 4 alone is three times or more the thickness of the base material layer 1.

The resin component used in the sealant layer 4 is not particularly limited as long as it can be heat-welded, and examples thereof include polyolefins, cyclic polyolefins, carboxylic acid-modified polyolefins, and carboxylic acid-modified cyclic polyolefins.

Specific examples of the polyolefin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and other polyethylene; homopolypropylene, polypropylene block copolymer (for example, propylene and ethylene block copolymer), and polypropylene. Polypropylene such as random copolymers of (eg, propylene and ethylene random copolymers); ethylene-butene-propylene tarpolymers; and the like. Among these polyolefins, polyethylene and polypropylene are preferable.

The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and 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. Can be mentioned. Examples of the cyclic monomer which is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specific examples thereof include cyclic diene such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkene is preferable, and norbornene is more preferable.

The carboxylic acid-modified polyolefin is a polymer modified by block-polymerizing or graft-polymerizing the polyolefin with a carboxylic acid. Examples of the carboxylic acid used for denaturation include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like.

The carboxylic acid-modified cyclic polyolefin is obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin in place of α, β-unsaturated carboxylic acid or its anhydride, or α, β with respect to the cyclic polyolefin. -A polymer obtained by block-polymerizing or graft-polymerizing an unsaturated carboxylic acid or an anhydride thereof. The same applies to the cyclic polyolefin modified with carboxylic acid. The carboxylic acid used for the modification is the same as that used for the modification of the acid-modified cycloolefin copolymer.

Among these resin components, carboxylic acid-modified polyolefin is preferable; and carboxylic acid-modified polypropylene is more preferable.

The sealant layer 4 may be formed by one kind of resin component alone, or may be formed by a blend polymer in which two or more kinds of resin components are combined. Further, the sealant layer 4 may be formed of only one layer, but may be formed of two or more layers with the same or different resin components.

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, but is preferably about 10 to 100 μm, for example. Is about 15 to 50 μm.

[Adhesive layer 5]
In the packaging material for batteries of the present invention, the adhesive layer 5 is a layer provided between the metal layer 3 and the sealant layer 4 as needed in order to firmly bond the metal layer 3 and the sealant layer 4. 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 three times or more the thickness of the base material layer 1. The thickness of the adhesive layer 5 alone may be three times or more the thickness of the base material layer 1 or less than three times.

The adhesive layer 5 is formed by an adhesive capable of adhering the metal layer 3 and the sealant layer 4. Regarding the adhesive used for forming the adhesive layer 5, the adhesive mechanism, the type of adhesive component, and the like are the same as in the case of the adhesive layer 2. Examples of the adhesive component used in the adhesive layer 5 include a polyolefin-based resin, more preferably a carboxylic acid-modified polyolefin, and particularly preferably a carboxylic acid-modified polypropylene.

The thickness of the adhesive layer 5 is not particularly limited as long as it functions as an adhesive layer, and examples thereof include about 2 to 50 μm, preferably about 15 to 30 μm.

[Coating layer]
In the packaging material for a battery of the present invention, for the purpose of improving designability, electrolytic solution resistance, scratch resistance, moldability, etc., if necessary, on the base material layer 1 (the metal layer of the base material layer 1). A coating layer may be provided on the side opposite to 3), if necessary. The coating layer is a layer located at the outermost layer when the battery is assembled.

The coating layer can be formed of, for example, polyvinylidene chloride, polyesteryl resin, urethane resin, acrylic resin, epoxy resin, or the like. Among these, the coating layer is preferably formed of a two-component curable resin. Examples of the two-component curable resin forming the coating layer include a two-component curable urethane resin, a two-component curable polyester resin, and a two-component curable epoxy resin. Moreover, you may mix the matting agent in the coating layer.

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, and organic substances. The shape of the matting agent is also not particularly limited, and examples thereof include a spherical shape, a fibrous shape, a plate shape, an amorphous shape, and a balloon shape. Specific examples of the matting agent include talc, silica, graphite, kaolin, montmoriloid, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, and aluminum oxide. , Neodium oxide, Antimon oxide, Titanium oxide, Cerium oxide, Calcium sulfate, Barium sulfate, Calcium carbonate, Calcium silicate, Lithium carbonate, Calcium benzoate, Calcium silicate, Magnesium stearate, Alumina, Carbon black, Carbon nanotubes, Examples thereof include refractory nylon, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper and nickel. These matting agents may be used alone or in combination of two or more. Among these matting agents, preferably silica, barium sulfate, and titanium oxide are mentioned from the viewpoint of dispersion stability, cost, and the like. Further, the matting agent may be subjected to various surface treatments such as an insulating treatment and a highly dispersible treatment on the surface.

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.

The thickness of the coating layer is not particularly limited as long as it exhibits the above-mentioned function as a coating layer, and examples thereof include about 0.5 to 10 μm, preferably about 1 to 5 μm.

4. The preparation method of a battery packaging material of the production method the present invention for a battery packaging material, as long as the laminate as a laminate of layers having a predetermined composition can be obtained, is not particularly limited, for example, the following methods are exemplified ..

First, a laminate in which the base material layer 1, the adhesive layer 2, and the metal layer 3 are laminated in this order (hereinafter, may be referred to as “laminate A”) is formed. Specifically, the laminate A is formed by extruding an adhesive used for forming the adhesive layer 2 on the base material layer 1 or, if necessary, on the metal layer 3 whose surface has been chemically converted, by a gravure coating method. It can be carried out by a dry lamination method in which the metal layer 3 or the base material layer 1 is laminated and the adhesive layer 2 is cured after being coated and dried by a coating method such as a method or a roll coating method.

Next, the sealant layer 4 is laminated on the metal layer 3 of the laminated body 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 onto the metal layer 3 of the laminated body A by a method such as a gravure coating method or a roll coating method. .. When the adhesive layer 5 is provided between the metal layer 3 and the sealant layer 4, for example, (1) the adhesive layer 5 and the sealant layer 4 are co-extruded onto the metal layer 3 of the laminated body A to be laminated. (Coextrusion lamination method), (2) Separately, a laminated body in which the adhesive layer 5 and the sealant layer 4 are laminated is formed, and this is laminated on the metal layer 3 of the laminated body A by the thermal lamination method. 3) An adhesive for forming the adhesive layer 5 is laminated on the metal layer 3 of the laminated body A by an extrusion method, a solution-coated high-temperature drying method, or a baking method, and the adhesive layer 5 is preliminarily sheet-shaped. A method of laminating the sealant layer 4 formed in the above by a thermal lamination method. (4) A melted adhesive layer 5 is formed between the metal layer 3 of the laminated body A and the sealant layer 4 formed in a sheet shape in advance. Examples thereof include a method of laminating the laminate A and the sealant layer 4 via the adhesive layer 5 (sand lamination method) while pouring.

When the coating layer is provided, 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 forming the coating layer to the surface of the base material layer 1. 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 the 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.

As described above, the base material layer 1 / the adhesive layer 2 / the metal layer whose surface is chemically treated as needed 3 / the adhesive layer 5 provided as needed / the sealant layer 4 / the coating provided as needed. A laminated body composed of layers is formed, but in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as needed, a hot roll contact type, a hot air type, a near-infrared type, etc. May be subjected to the heat treatment of. Examples of the conditions for such heat treatment include 1 to 5 minutes at 150 to 250 ° C.

In the packaging material for batteries of the present invention, each layer constituting the laminated body improves or stabilizes film forming property, laminating process, aptitude for secondary processing (pouching, embossing) of the final product, etc., as necessary. Therefore, surface activation treatments such as corona treatment, blast treatment, oxidation treatment, and ozone treatment may be performed.

5. Applications of Battery Packaging Materials The battery packaging materials of the present invention are used as packaging materials for sealing and accommodating battery elements such as positive electrodes, negative electrodes, and electrolytes.

Specifically, a battery element having at least a positive electrode, a negative electrode, and an electrolyte is used in the battery packaging material of the present invention, with metal terminals connected to each of the positive electrode and the negative electrode projecting outward. A battery using a battery packaging material can be produced by covering the peripheral edge of the element so that a flange portion (a region where the sealant layers come into contact with each other) can be formed, and heat-sealing the sealant layers of the flange portion to seal each other. Provided. When the battery element is housed 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 inside (the surface in contact with the battery element).

The packaging material for a battery 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 packaging material for a battery of the present invention is applied is not particularly limited, and for example, a lithium ion battery, a lithium ion polymer battery, a lead livestock battery, a nickel / hydrogen livestock battery, and a nickel / cadmium livestock battery. , Nickel / iron livestock battery, nickel / zinc livestock battery, silver oxide / zinc livestock battery, metal air battery, polyvalent cation battery, condenser, capacitor and the like. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries can be mentioned as suitable application targets of the packaging material for batteries of the present invention.

As mentioned above, in particular, the battery packaging material used for large secondary batteries such as secondary batteries for automobiles has a large size, so that the curl has a great influence on the productivity of the battery. However, the battery packaging material of the present invention is particularly useful as a battery packaging material for a secondary battery for automobiles because curl after molding is effectively suppressed.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Examples 1-3 and Comparative Examples 1-8
<Manufacturing of packaging materials for batteries>
By laminating the adhesive layer 5 and the sealant layer 4 on the laminated body in which the base material layer 1 / adhesive layer 2 / metal layer 3 are laminated in order by the thermal laminating method, the base material layer 1 / adhesive layer 2 / metal A packaging material for a battery was produced, which was composed of a laminate in which a layer 3 / an adhesive layer 5 / a sealant layer 4 were laminated in this order. Details of the manufacturing conditions for the packaging material for batteries are as shown below.

First, the adhesive layer 2 is formed on one surface of the base material layer 1 so as to have a thickness of 3 μm, and is bonded to the chemical conversion-treated surface of the metal layer 3 under pressure and heat to form the base material layer 1 / adhesive layer 2 / metal layer 3. A laminated body in which they were laminated in order was produced. Separately, the acid-modified polypropylene resin constituting the adhesive layer 5 (unsaturated carboxylic acid graft-modified random polypropylene graft-modified with unsaturated carboxylic acid) and polypropylene (random copolymer) constituting the sealant layer 4 are co-extruded. To prepare a two-layer coextruded film composed of an adhesive layer 5 and a sealant layer 4.

Next, the metal layer of the laminated body composed of the base material layer 1 / adhesive layer 2 / metal layer 3 produced above is superposed so that the adhesive layer 5 of the two-layer coextruded film produced above is in contact with the metal layer 3. By heating to 120 ° C. and performing thermal lamination, 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 was obtained. After cooling the obtained laminate once, it is heated to 180 ° C., and the temperature is maintained for 1 minute to perform heat treatment, whereby the packaging materials for batteries of Examples 1-3 and Comparative Examples 1-8 are obtained. Obtained.

The laminated structure of the battery packaging material produced in Examples 1-3 and Comparative Examples 1-8 and the thickness of each layer are as follows. The laminate of PET and nylon forming the base material layer 1 is obtained by adhering the PET film and the 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.
(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)
(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 3)
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)

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

As is clear from the results shown in Table 1, the total thickness of the adhesive layer 5 and the sealant layer 4 is three times or more the thickness of the base material layer 1 even when molded under the severe condition of a molding depth of 6 mm. In the battery packaging material of Examples 1-3, curl was effectively suppressed. On the other hand, in the battery packaging material of Comparative Example 1-8 in which the total thickness of the adhesive layer 5 and the sealant layer 4 is less than three times the thickness of the base material layer 1, the curl becomes large when molded at a molding depth of 6 mm. , It was inferior in formability as compared with Examples 1-3.

1 Base material layer 2 Adhesive layer 3 Metal layer 4 Sealant layer 5 Adhesive layer 10 Battery packaging material M Molded part P end

Claims (8)

At least, it is composed of a laminate in which a base material layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated.
The base material layer is formed of one layer of a stretched polyester resin film, one layer of a stretched polyamide resin film, or a laminated film in which a stretched polyester resin film and a stretched polyamide resin film are laminated with a urethane-based adhesive.
Thickness of the base material layer (However, when the base material layer is formed of a laminated film in which the stretched polyester resin film and the stretched polyamide resin film are laminated with the urethane-based adhesive, the group The thickness of the material layer does not include the thickness of the urethane-based adhesive.) Is 12 μm or more and 25 μm or less.
The total thickness of the adhesive layer and the sealant layer is 60 μm or more and 80 μm or less.
The adhesive layer is formed of acid-modified polyolefin and 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 packaging material for a battery in which the total thickness of the adhesive layer and the sealant layer is three times or more the thickness of the base material layer. The packaging material for a battery according to claim 1, wherein the thickness of the laminate is 160 μm or less. The packaging material for a battery according to claim 1 or 2, wherein the sealant layer is formed of an unstretched resin film. The battery packaging material according to any one of claims 1 to 3, wherein the metal layer is formed of aluminum foil. The aluminum foil has a 0.2% proof stress when a tensile test is conducted in a direction parallel to the MD direction and a 0.2% proof stress when a tensile test is conducted in a direction parallel to the TD direction. in 55N / mm ² or more 140 N / mm ² or less in the range both, the packaging material for a battery according to claim 4. The packaging material for a battery according to any one of claims 1 to 5, wherein at least one surface of the metal layer is subjected to chemical conversion treatment. The battery packaging material according to any one of claims 1 to 6, which is a packaging material for a secondary battery. 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 claims 1 to 7.

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