JP6773155B2 - Battery packaging material - Google Patents

Description

The present invention relates to a packaging material for a battery having excellent insulating properties.

Conventionally, various types of batteries have been developed, but in all batteries, a packaging material is an indispensable member for sealing battery elements such as electrodes and electrolytes. Conventionally, metal packaging materials have been widely used for battery packaging.

On the other hand, in recent years, with the improvement of high performance of 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 layer / a metal layer / a sealant layer is sequentially laminated has been proposed. ing. A polyamide film such as nylon is widely used as a base material layer for such a packaging material for batteries (see, for example, Patent Document 1).

In addition, such battery packaging materials have conventionally been mainly used for small electric appliances such as mobile phones, smartphones, laptop computers, and tablets, but in recent years, they have also been used for electric bicycles, automobiles, power storage devices, and the like. Tends to be. Along with this, the size and capacity of batteries used as packaging materials for batteries are increasing, and there is a tendency to modularize (stack a plurality of batteries) and use a plurality of batteries (for example, patent documents). See 2).

However, since the heat insulating property of the polyamide film widely used as the base material layer is low, when the base material layer is formed of the polyamide film, the insulating property of the modularized high-capacity battery used for automobiles and the like is lowered. There is a fear. For example, in a part of a modularized battery, if the insulation property is lowered and a discharge occurs, another adjacent battery may be destroyed and the battery function may be impaired. In particular, batteries used in automobiles and the like are required to have durability in a harsh environment, but a polyamide film has a problem that its insulating property is more likely to be lowered in a high humidity environment.

Further, with the recent demand for higher capacity batteries, the packaging materials for batteries are required to be further thinned. For example, when the thickness of the battery packaging material is reduced to 120 μm or less, there is a problem that the insulating property of the battery packaging material tends to decrease.

Japanese Unexamined Patent Publication No. 2008-288117 Japanese Unexamined Patent Publication No. 2013-201027

A main object of the present invention is at least an excellent insulating property in a battery packaging material composed of a laminate in which a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated, even in a high humidity environment. To provide a packaging material for a battery having the above.

The present inventors have made diligent studies to solve the above-mentioned problems. As a result, at least in the packaging material for batteries composed of a laminate in which a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated, the base material layer has a volume resistivity of 1 × 10 ¹⁵ Ω · cm or more. It has been found that excellent insulating properties are exhibited by having the resin layer A made of the thermoplastic resin of the above. 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, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated.
The base material layer is a packaging material for batteries, which has a resin layer A made of a thermoplastic resin having a volume resistivity of 1 × 10 ¹⁵ Ω · cm or more.
Item 2. Item 2. The packaging material for a battery according to Item 1, wherein the thickness of the resin layer A is in the range of 9 to 25 μm.
Item 3. Item 2. The packaging material for a battery according to Item 1 or 2, wherein the resin layer A is formed of at least one of polyethylene terephthalate and polybutylene terephthalate.
Item 4. Item 2. The packaging material for a battery according to any one of Items 1 to 3, wherein the thickness of the laminate is 125 μm or less.
Item 5. Item 2. The battery packaging material according to any one of Items 1 to 4, wherein the metal layer is formed of an aluminum foil.
Item 6. Item 2. The packaging material for a battery according to any one of Items 1 to 5, wherein at least one surface of the metal layer is subjected to chemical conversion treatment.
Item 7. Item 2. The battery packaging material according to any one of Items 1 to 6, which is a packaging material for a secondary battery.
Item 8. 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 7.

The packaging material for a battery of the present invention is composed of at least a laminate in which a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated, and the base material layer has a volume resistivity of 1 × 10 ¹⁵ Ω · cm. Since it has the resin layer A made of the above thermoplastic resin, it has excellent insulating properties.

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.

The packaging material for a battery of the present invention is composed of at least a laminate in which a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated, and the base material layer has a volume resistivity of 1 × 10 ¹⁵ Ω · cm. It is characterized by having a resin layer A made of the above thermoplastic resin. 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 is composed of at least a laminate in which a base material layer 1, an adhesive layer 2, 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, in the packaging material for a battery of the present invention, as shown in FIG. 2, an adhesive layer 5 is provided between the metal layer 3 and the sealant layer 4 as needed for the purpose of enhancing their adhesiveness. You may.
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).

The thickness of the laminate constituting the battery packaging material of the present invention is not particularly limited, but is preferably 125 μm or less, more preferably 125 μm or less, from the viewpoint of making the battery packaging material thinner and providing excellent insulation. The range is about 90 to 120 μm.

2. 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 base material layer 1 is characterized by having a resin layer A made of a thermoplastic resin having a volume resistivity of 1 × 10 ¹⁵ Ω · cm or more. In the present invention, when the base material layer 1 has the resin layer A made of such a thermoplastic resin having a high volume resistivity, the thickness of the packaging material for the battery is thin (for example, 120 μm or less). It has excellent insulating properties even in a high humidity environment (for example, 23 ° C., relative humidity 90%).

From the viewpoint of further enhancing the insulating property of the packaging material for batteries of the present invention, the volume resistivity of the thermoplastic resin forming the resin layer A is preferably 1 × 10 ¹⁶ Ω · cm or more, more preferably 1 ×. 10 ¹⁷ Ω · cm or more can be mentioned. The upper limit of the volume resistivity of the thermoplastic resin forming the resin layer A is usually about 1 × 10 ¹⁹ Ω · cm Ω · cm. In the present invention, the method for measuring the volume resistivity of the thermoplastic resin forming the resin layer A is a value measured under the conditions of 23 ° C. and 50% relative humidity by a method in accordance with the provisions of JIS C 2151.

The thermoplastic resin forming the resin layer A is not particularly limited as long as it has the above-mentioned volumetric resistance, but is preferably a polyolefin resin such as polyethylene or polypropylene; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or the like. Polyethylene resin; Fluorine-based resins such as ethylene tetrafluoride / propylene hexafluoride copolymer, ethylene tetrafluoride / perfluoroalkoxyethylene copolymer, ethylene tetrafluoride / ethylene copolymer; polystyrene, styrene / butadiene -Acrylonitrile copolymer and the like can be mentioned. Among these, polyethylene terephthalate and polybutylene terephthalate are particularly preferable from the viewpoints of insulation, heat resistance, molding processability and the like. As the thermoplastic resin forming the resin layer A, one type may be used alone, or two or more types may be used in combination.

The thickness of the resin layer A is preferably about 9 to 25 μm, more preferably about 12 to 25 μm, from the viewpoint of exhibiting excellent insulating properties while suppressing an increase in the thickness of the battery packaging material.

Further, from the viewpoint of exhibiting excellent insulating properties in a high humidity environment, the water absorption rate of the thermoplastic resin forming the resin layer A is preferably 0.5% or less. The water absorption rate of the thermoplastic resin is a value obtained by measuring the water absorption rate after 24 hours at 23 ° C. in accordance with the method specified in JIS K 7209.

Further, from the viewpoint of exhibiting excellent insulating properties in a high humidity environment, the wetting tension of the surface of the resin layer A is preferably 35 mN / m or less. This is because if the wetting tension is high, moisture is likely to be adsorbed, which may reduce the insulating property. The wettability of the thermoplastic resin is a value measured at 23 ° C. in a 50% RH atmosphere in accordance with the method specified in JIS K 6768.

The base material layer 1 may be formed of a single layer of the resin layer A, or a plurality of the resin layer A and another resin layer (composed of a resin having a volume resistivity of less than 1 × 10 ¹⁵ Ω · cm). It may be formed by a layer of. Examples of the resin forming the other resin layer include polyamide resin, epoxy resin, acrylic resin, fluororesin, polyurethane resin, silicon resin, phenol resin, and resin films such as mixtures and copolymers thereof. Among these, a polyamide resin is preferable. 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. Nylon 6 is preferable. As the resin forming the other resin layer, one type may be used alone, or two or more types may be used in combination.

When the base material layer 1 is formed of a resin layer A and a plurality of other resin layers, these layers may be laminated via an adhesive component such as an adhesive or an adhesive resin, and are used. The types and amounts of the adhesive components are the same as 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. 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.

Additives such as an antioxidant, a slip agent, an antiblocking agent, and a water repellent may be added to each layer forming the base material layer 1, if necessary.

The total thickness of the base material layer 1 is not particularly limited as long as it functions as a base material layer, and examples thereof include about 10 to 50 μm, preferably about 15 to 25 μm.

[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 in order to firmly bond them.

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; Polyurethane-based adhesives; Epoxy resins; Phenolic resin-based resins; Polyolefin-based resins such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefins 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 system 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 the formation of wrinkles and pinholes in the metal layer 3 during the manufacture of packaging materials for batteries, 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, chromate 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. Treatment; Chromate phosphate treatment using a phosphoric acid compound such as sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphate; aminoated phenol having repeating units 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. Further, 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 linear or branched alkyl groups having 1 to 4 carbon atoms such as tert-butyl groups. Examples of the hydroxyalkyl groups represented by X, R ¹ and R ² include hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 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 aminated 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. In addition, 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 dipping 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.

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 propylene and ethylene (eg, random copolymers of propylene and ethylene); 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 means that a part of the monomer constituting the cyclic polyolefin is copolymerized 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 polymerization or graft polymerization of unsaturated carboxylic acid or its anhydride. 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 functions as a sealant layer, and examples thereof include about 10 to 100 μm, preferably 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.

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., as 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 and cost. 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.

3. 3. Method for Manufacturing Battery Packaging Material The method for producing the battery packaging material of the present invention is not particularly limited as long as a laminate in which each layer having a predetermined composition is laminated can be obtained, and examples thereof include the following methods. ..

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 on 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 laminated body 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 / adhesive layer 2 / metal layer whose surface has been chemically converted as needed 3 / adhesive layer 5 provided as needed / sealant layer 4 / 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. It 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.

4. 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 made of 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 are projected 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 contact 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.

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

Example 1-6 and Comparative Example 1-2
<Manufacturing of packaging materials for batteries>
Using the base material layer, metal layer, and adhesive layer shown in Examples 1-6 and Comparative Example 1-2 below, a laminate in which the base material layer 1 / adhesive layer 2 / metal layer 3 were laminated in this order was prepared. .. Specifically, the following adhesive layer 2 is formed on one surface of the base material layer 1, 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 by coextrusion. A two-layer coextruded film composed of an adhesive layer 5 and a sealant layer 4 was produced. Next, the metal layer of the laminate 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 the temperature 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 for heat treatment to obtain the packaging materials for batteries of Examples 1-6 and Comparative Example 1-2. Obtained. The laminated structure of the battery packaging materials obtained in Examples 1-6 and Comparative Example 1-2 and the thickness of each layer are as follows. The metal layer 3, the adhesive layer 2, and the sealant layer 4 are common to Examples 1-6 and Comparative Example 1-2.

<Example 1>
(Base material layer 1)
This is a PET resin film (thickness 12 μm) produced by sequentially biaxially stretching an unstretched raw film made of a raw material containing polyethylene terephthalate as a main component by a tenter method and then heat-treating at 210 ° C. The stretch ratio was 3.2 times in the flow direction (MD) and 3.2 times in the width direction (TD).
(Metal layer 3)
An aluminum foil (ALM1: 8079 material) having the following physical properties was used. The tensile strength at break and the elongation at break are values measured by a method according to JIS K7127, respectively. The 0.2% proof stress is a value measured by a tensile test specified in JIS Z 2241.
-Tensile breaking strength: 86.0 MPa in the MD direction, 87.2 MPa in the TD direction
-Tension breaking elongation: 14.3% in MD direction, 12.2% in TD direction
0.2% proof stress: 38.6 MPa in MD direction, 37.5 MPa in TD direction
(Adhesive layer 2)
The following adhesive was used as the adhesive layer 2 for adhering the base material layer 1 and the metal layer 3.
Glass transition point -5~5 ° C., a weight average molecular weight 10 to 40 × 10 ^3, hydroxyl group equivalent weight 0.7-1
.. Urethane resin adhesive (laminated structure) in which 9 / mol polyol compound and aromatic isocyanate mainly composed of trimethylolpropane (TMP) adduct of toluene diisocyanate (TDI) are mixed at a ratio of 1: 3.
PET resin film (12 μm) / adhesive layer (3 μm) / aluminum foil (35 μm) / adhesive layer (30 μm) / sealant layer (30 μm)

<Example 2>
(Base material layer 1)
It is a laminate in which the PET resin film (12 μm) of Example 1 and the following nylon film are bonded with an adhesive (thickness 3 μm) forming an adhesive layer 2. A nylon film (thickness: 15 μm) produced by simultaneously biaxially stretching an unstretched raw film made of a raw material containing nylon 6 as a main component by a tubular method and then heat-treating at 200 ° C. The draw ratio was 3.0 times in the flow direction (MD) and 3.3 times in the width direction (TD).
(Laminate structure)
PET resin film (12 μm) / adhesive (3 μm) / nylon film (15 μm) / adhesive layer (3 μm) / aluminum foil (35 μm) / adhesive layer (30 μm) / sealant layer (30 μm)

<Example 3>
(Base material layer 1)
The PET resin film produced in the same manner as in Example 1 and the nylon film (thickness 15 μm) of Example 2 were bonded with an adhesive (thickness 3 μm) forming the adhesive layer 2 except that the thickness was 9 μm. It is a laminated body.
(Laminate structure)
PET resin film (9 μm) / adhesive (3 μm) / nylon film (15 μm) / adhesive layer (3 μm) / aluminum foil (35 μm) / adhesive layer (30 μm) / sealant layer (30 μm)

<Example 4>
(Base material layer 1)
A PBT resin film produced by simultaneous biaxial stretching of an unstretched raw film made of a resin containing 8% by weight of polyethylene terephthalate added to polybutylene terephthalate by the tubular method and then heat-treating at 205 ° C. Is. The draw ratio was 3.8 times in the flow direction (MD) and 3.8 times in the width direction (TD).
(Laminate structure)
PBT resin film (15 μm) / adhesive layer (3 μm) / aluminum foil (35 μm) / adhesive layer (30 μm) / sealant layer (30 μm)

<Example 5>
(Base material layer 1)
It was produced by extruding polyethylene terephthalate resin, thermoplastic polyester elastomer, and nylon 6 by the T-die method to prepare a coextruded film, then biaxially stretching in the MD and TD directions by the sequential stretching method and heat-treating at 200 ° C. , PET resin film (thickness 4 μm) / adhesive (thickness 1 μm) / nylon film (thickness 20 μm). The draw ratio was 3.4 times in the flow direction (MD) and 3.8 times in the width direction (TD). The adhesive is the same as that forming the adhesive layer 2.
(Laminate structure)
PET resin film (4 μm) / adhesive (1 μm) / nylon film (20 μm) / adhesive layer (3 μm) / aluminum foil (35 μm) / adhesive layer (30 μm) / sealant layer (30 μm)

<Example 6>
(Base material layer 1)
One layer of PET resin film prepared in the same manner as in Example 1 was used except that the thickness was 6 μm.
(Laminate structure)
PET resin film (6 μm) / adhesive layer (3 μm) / aluminum foil (35 μm) / adhesive layer (30 μm) / sealant layer (30 μm)

<Comparative example 1>
(Base material layer 1)
One layer of nylon film produced in the same manner as in Example 2 was used except that the thickness was 25 μm.
(Laminate structure)
Nylon film (25 μm) / adhesive layer (3 μm) / aluminum foil (35 μm) / adhesive layer (30 μm) / sealant layer (30 μm)

<Comparative example 2>
(Base material layer 1)
One layer of nylon film produced in the same manner as in Example 2 was used except that the thickness was 15 μm.
(Laminate structure)
Nylon film (15 μm) / adhesive layer (3 μm) / aluminum foil (35 μm) / adhesive layer (30 μm) / sealant layer (30 μm)

<Measurement of volume resistivity>
In each of the battery packaging materials obtained in Examples and Comparative Examples, a resin layer located at the outermost layer of the base material layer 1 (in each base material layer, formed of a resin having the largest volume resistivity) is provided. The volume resistivity of the resin to be formed was measured under the conditions of 23 ° C. and 50% relative humidity by a method in accordance with the regulations of JIS C 2151. The results are shown in Table 1.

<Measurement of dielectric breakdown voltage>
The insulation breakdown voltage of each battery packaging material obtained in Examples and Comparative Examples was adjusted to 23 ° C. and 50% relative humidity by a method in accordance with the provisions of JIS C 2110-1 (short-time method), and 23. The measurement was performed by applying from the base material layer side under the conditions of ° C. and relative humidity of 90%. Insulation was evaluated according to the following criteria. The results are shown in Table 1.
◎ ◎: 8 kV or more ◎: 7 kV or more, less than 8 kV ○: 6 kV or more, less than 7 kV Δ: 5 kV or more, less than 6 kV ×: less than 5 kV

<Evaluation by electrolytic corrosion test method>
Using the electrolytic corrosion test method, the insulation of the surface of the base material with respect to water of each battery packaging material obtained in Examples and Comparative Examples was evaluated. First, each battery packaging material was cut into 80 mm (MD direction, vertical direction) × 120 mm (TD direction, horizontal direction). Next, by performing plastic working using a mold, a molded product in which a concave mold having a depth of 6 mm and a length and width of 50 mm × 35 mm was formed from each battery packaging material was prepared. With water immersed in the molded part that is a part of this molded product, the part immersed in water and a part of the molded product are connected with a copper wire, and a voltage of 3 V is applied to the part to form the metal layer 3. It was evaluated whether or not peeling (delamination) between the adhesive layer 2 and the metal layer 3 occurred due to the elution of the aluminum foil. The results are shown in Table 1.
○: No peeling ×: With peeling

As is clear from the results shown in Table 1, in Examples 1-6, the base material layer 1 contains a resin layer formed of a thermoplastic resin having a volume resistivity of 1 × 10 ¹⁵ Ω · cm or more. It can be seen that the insulation breakdown voltage of the packaging material for batteries is high and the insulation is excellent. In particular, in Examples 1 to 4 in which the thickness of the resin layer was thicker than 9 μm, the insulating property was particularly high. On the other hand, in Comparative Example 1-2 in which the base material layer 1 did not contain a resin layer formed of a thermoplastic resin having a volume resistivity of 1 × 10 ¹⁵ Ω · cm or more, the insulating property was low.

1 Base material layer 2 Adhesive layer 3 Metal layer 4 Sealant layer 5 Adhesive layer

Claims (7)

At least, it is composed of a laminate in which a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated.
The base material layer has a resin layer A made of a thermoplastic resin having a volume resistivity of 1 × 10 ¹⁵ Ω · cm or more.
The resin layer A is formed of at least one of polyethylene terephthalate and polybutylene terephthalate.
The wetting tension on the surface of the resin layer A is 35 N / m or less.
The metal layer 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. both are formed of aluminum foil in the 55N / mm ² or more 140 N / mm ² or less in the range of packaging material for a battery. The packaging material for a battery according to claim 1, wherein the thickness of the resin layer A is in the range of 9 μm or more and 25 μm or less. The packaging material for a battery according to claim 1 or 2, wherein the thickness of the metal layer is in the range of 20 μm or more and 50 μm or less. The packaging material for a battery according to any one of claims 1 to 3 , wherein the thermoplastic resin forming the resin layer A has a water absorption rate of 0.5% or less. The packaging material for a battery according to any one of claims 1 to 4 , 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 5 , 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 6 .