JP6245328B2 - Battery packaging materials - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a battery packaging material that is less prone to pinholes and cracks during molding and has excellent moldability.

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

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

  Therefore, in recent years, a film-like laminate in which a base material / metal layer / sealant layer are sequentially laminated has been proposed as a packaging material for batteries that can be easily processed into various shapes and can be reduced in thickness and weight. Yes. However, such a film-shaped packaging material has a drawback that it is thinner than a metal packaging material and easily causes pinholes and cracks during molding. When pinholes or cracks occur in battery packaging materials, the electrolyte can penetrate into the metal layer to form metal deposits, which can result in short circuits. It is indispensable for the battery packaging material to have a characteristic that does not easily cause pinholes during molding, that is, excellent moldability.

  Conventionally, in order to improve the moldability of a film-like battery packaging material, various studies have been conducted focusing on an adhesive layer for bonding a metal layer. For example, Patent Document 1 discloses that in the laminated packaging material including an inner layer made of a resin film, a first adhesive layer, a metal layer, a second adhesive layer, and an outer layer made of a resin film, the first adhesive layer And at least one of the second adhesive layer is formed of an adhesive composition containing a resin having an active hydrogen group in the side chain, a polyfunctional isocyanate, and a polyfunctional amine compound, thereby providing a reliability against deeper molding. It is disclosed that a highly packaging material can be obtained.

  As represented by Patent Document 1, conventionally, in a battery packaging material composed of a film-like laminate, a technique for improving moldability by paying attention to a compounding component of an adhesive layer for bonding a metal layer to another layer Although many studies have been made, few techniques have been reported regarding techniques for improving moldability by focusing on the physical properties of the battery packaging material as a whole.

JP 2008-287971 A

Ota Satoshi, Pressing Technology Manual, published by Nikkan Kogyo Shimbun, issued July 30, 1981, 1-3 pages

  The main object of the present invention is that a battery packaging material comprising a film-like laminate in which at least a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated is less likely to cause cracks and pinholes during molding. It is to provide a technique for providing excellent moldability.

  The present inventor has intensively studied to solve the above problems. As a result, in a battery packaging material comprising a laminate in which at least a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated, stress at 40% elongation in the MD direction of the laminate is / 10% elongation Surprisingly, the sum (A + B) of the stress value A at the time and the stress at the time of 40% elongation in the TD direction / 10 the stress value B at the time of 10% elongation satisfies the relationship of A + B ≧ 2.50. In addition, it has been found that the battery packaging material can be provided with remarkably excellent moldability, and the incidence of pinholes and cracks during molding can be greatly reduced. The present invention has been completed by further studies based on these findings.

That is, this invention provides the battery packaging material and battery of the aspect hung up below.
Item 1. It consists of a laminate in which at least a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated,
The laminate is the sum of the stress A at 40% elongation / 10% elongation in the MD direction and the stress value A at 40% elongation / 10% in the TD direction (A + B). ) Satisfy the relationship of A + B ≧ 2.50.
Item 2. Item 4. The battery packaging material according to Item 1, wherein A and B satisfy a relationship of A <B. Item 3. Item 3. The battery packaging material according to Item 1 or 2, wherein A is A ≧ 1.19, and B is B ≧ 1.31.
Item 4. The tensile strength at break in the MD direction and TD direction of the base material layer is both 200 MPa or more, and the tensile elongation at break in the MD direction and TD direction of the base material layer is both in the range of 70 to 130%. The packaging material for batteries according to any one of Items 1 to 3.
Item 5. The metal layer has both a 0.2% proof stress when a tensile test in a parallel direction with respect to the MD direction and a 0.2% proof stress when a tensile test in a parallel direction with respect to the TD direction are performed. Item 5. The battery packaging material according to any one of Items 1 to 4, which is an aluminum foil in a range of ˜140 N / mm ² .
Item 6. Item 6. The battery packaging material according to any one of Items 1 to 5, wherein the base material layer is composed of at least one of a polyamide resin and a polyester resin.
Item 7. Item 7. The battery packaging material according to any one of Items 1 to 6, wherein a chemical conversion treatment is performed on at least one surface of the metal layer.
Item 8. Item 8. The battery packaging material according to any one of Items 1 to 7, which is a packaging material for a secondary battery.
Item 9. Item 9. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is accommodated in the battery packaging material according to any one of Items 1 to 8.

  According to the battery packaging material of the present invention, the stress A at 40% elongation in the MD direction as a whole battery packaging material / the stress value A at 40% elongation in the TD direction and the stress at 40% elongation in the TD direction / 10. Since the sum (A + B) of the stress value B at% elongation satisfies the relationship of A + B ≧ 2.50, the occurrence of pinholes, cracks and the like during the molding of the battery packaging material can be suppressed. Furthermore, since the battery packaging material of the present invention has excellent moldability, it can also contribute to the improvement of productivity.

It is a figure which shows an example of the cross-section of the packaging material for batteries of this invention. It is a figure which shows an example of the cross-section of the packaging material for batteries of this invention. It is a schematic diagram for demonstrating the relationship between the stress at the time of shaping | molding of the packaging material for batteries, and a distortion | strain.

  The battery packaging material of the present invention is composed of a laminate in which at least a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated, and the laminate is a stress at 40% elongation in the MD direction / 10%. The sum (A + B) of the stress value A at the time of elongation and the stress value B at the time of 40% elongation / 10% stress at the time of elongation in the TD direction satisfies the relationship of A + B ≧ 2.50. To do. Hereinafter, the battery packaging material of the present invention will be described in detail.

1. As shown in FIG. 1, the battery packaging material comprises a laminate in which at least a base material layer 1, an adhesive layer 2, a metal layer 3, and a sealant layer 4 are sequentially laminated. In the battery packaging material of the present invention, the base material layer 1 is the outermost layer, and the sealant layer 4 is the innermost layer. That is, when the battery is assembled, the sealant layers 4 positioned at the periphery of the battery element are thermally welded to seal the battery element, thereby sealing the battery element.

  Further, as shown in FIG. 2, the battery packaging material of the present invention is provided with an adhesive layer 5 between the metal layer 3 and the sealant layer 4 as necessary for the purpose of enhancing the adhesiveness thereof. May be.

2. Physical Properties of Battery Packaging Material The battery packaging material of the present invention comprises a laminate comprising the battery packaging material, stress at 40% elongation in the MD direction / 10% stress at 10% elongation, and in the TD direction. The sum (A + B) of the stress at 40% elongation / 10 the stress at the time of 10% elongation (A + B) satisfies the relationship of A + B ≧ 2.50. Specifically, the stress value A at 40% elongation / 10 stress in the flow direction (MD direction) of the laminate constituting the battery packaging material and the stress value A at 10% elongation are perpendicular to the MD direction ( The sum (A + B) of the stress B at the time of 10% elongation / the stress value B at the time of 10% elongation (A + B) in the TD direction) satisfies the relationship of A + B ≧ 2.50. In addition, when the battery packaging material is a wound body of a sheet-like laminate, when the laminate is unwound from the winder, the length direction (unwinding direction) of the laminate is the MD direction. The width direction of the laminate is the TD direction. In the present invention, the stress at 40% elongation and the stress at 10% elongation in the MD direction and the TD direction of the laminate are values measured according to the method defined in JIS K7127, respectively.

  In the battery packaging material of the present invention, since the MD and TD stresses of the laminate satisfy such a relationship, the occurrence of pinholes and cracks during molding is suppressed, and excellent molding is achieved. Have sex. The details of the mechanism by which the occurrence of pinholes and cracks during molding is suppressed by setting the physical properties of the battery packaging material of the present invention as described above are not necessarily clear. Can be thought of as That is, the stress values A and B at 40% elongation / 10% elongation at the MD direction and the TD direction have a large value of A + B ≧ 2.50. Thereby, for example, the stress change near the yield point of the stress-strain curve becomes gentle as represented by the line A in the schematic diagram showing the relationship between the stress and the strain at the time of molding the battery packaging material of FIG. Therefore, rapid deformation (elongation) of the battery packaging material is suppressed, and as a result, the deformation (elongation) of the metal layer 3 can be gradually changed. For this reason, at the time of shaping | molding of the packaging material for batteries, it is thought that the metal layer 3 can be made to follow a metal mold | die shape moderately, and generation | occurrence | production of a pinhole, a crack, etc. is suppressed. The upper limit value of A + B is usually about 3.50.

  On the other hand, in the battery packaging material, when A + B <2.50, the stress change near the yield point of the stress-strain curve increases as shown by line B in FIG. ) Also changes significantly. For this reason, it is considered that it becomes difficult to cause the metal layer 3 to follow the shape of the mold appropriately at the time of molding the battery packaging material, and pinholes, cracks and the like are likely to occur.

  It is particularly preferable that the battery packaging material satisfies the relationship of A + B ≧ 2.65 from the viewpoint of suppressing the occurrence of pinholes, cracks and the like during the molding of the battery packaging material and further improving the moldability. Furthermore, from the same viewpoint, it is preferable that A and B satisfy the relationship of A <B. From the same viewpoint, it is preferable that A is A ≧ 1.19, and B is preferably B ≧ 1.31, A is A ≧ 1.24, and B Is particularly preferably B ≧ 1.47.

  Although it does not restrict | limit especially as the value of the stress at the time of 40% expansion | extension in the MD direction of the packaging material for batteries, Preferably it is about 40-90 MPa, More preferably, about 60-80 MPa is mentioned. Moreover, it does not restrict | limit especially as a stress at the time of 40% expansion | extension in the TD direction of the battery packaging material, Preferably it is about 50-100 MPa, More preferably, about 60-80 MPa is mentioned. Although it does not restrict | limit especially as a stress at the time of 10% expansion | extension in the MD direction of the packaging material for batteries, Preferably it is about 30-70 MPa, More preferably, about 45-60 MPa is mentioned. Moreover, it does not restrict | limit especially as a stress at the time of 10% expansion | extension of the packaging material for batteries, Preferably it is about 20-60 MPa, More preferably, about 40-55 MPa is mentioned.

  In order to set the physical properties of the battery packaging material of the present invention to such specific values, the composition and physical properties of the base material layer 1, the adhesive layer 2, the metal layer 3, and the sealant layer 4 constituting the battery packaging material. The thickness and the like may be adjusted as appropriate. Below, each layer which comprises the packaging material for batteries of this invention is explained in full detail.

3. Composition of each layer forming base material for battery [base material layer 1]
In the battery packaging material of the present invention, the base material layer 1 is a layer forming the outermost layer. The material for forming the base material layer 1 is not particularly limited as long as it has insulating properties. Examples of the material for forming the base material layer 1 include resin films such as polyester resin, polyamide resin, epoxy resin, acrylic resin, fluorine resin, polyurethane resin, silicon resin, phenol resin, and mixtures and copolymers thereof. Can be mentioned. Among these, Preferably a polyester resin and a polyamide resin are mentioned, More preferably, a biaxially stretched polyester resin and a biaxially stretched polyamide resin are mentioned. Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolyester, 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, polymetaxylylene adipamide (MXD6), and the like. It is done.

  The base material layer 1 (resin film constituting the base material layer 1) has a tensile breaking strength in the MD direction and the TD direction of 200 MPa or more, and a tensile breaking elongation in the MD direction and the TD direction of 70 to 130. %, Preferably the tensile strength in the MD and TD directions is in the range of 250 to 380 MPa, and the tensile elongation in the MD and TD directions is in the range of 80 to 125%. More preferably. When the tensile breaking strength and tensile breaking elongation of the base material layer 1 have such values, the A and B of the battery packaging material of the present invention can be suitably set to the above relationship, and molding Generation of pinholes and cracks at the time can be further effectively suppressed, and the moldability can be further improved. In addition, the tensile breaking strength and the tensile breaking elongation of the base material layer 1 are values obtained by measuring by a method based on JIS K7127, respectively.

  Although the base material layer 1 may be formed from the resin film of 1 layer, in order to improve pinhole resistance and insulation, it may be formed with the resin film of 2 layers or more. 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. Is the same as in the case of the adhesive layer 2 or the adhesive layer 5 described later. In addition, it does not restrict | limit especially as a method of laminating | stacking two or more resin films, A well-known method is employable, For example, a dry lamination method, a sand lamination method, etc. are mentioned, Preferably a dry lamination method is mentioned. When laminating by the dry lamination method, it is preferable to use a urethane-based adhesive as the adhesive layer. At this time, the thickness of the adhesive layer is, for example, about 2 to 5 μm.

  The thickness of the base material layer 1 is not particularly limited as long as the battery packaging material satisfies the above physical properties while exhibiting the function as the base material layer. For example, the thickness is about 10 to 50 μm, preferably about 15 to 25 μm. Is mentioned.

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

  The adhesive layer 2 is formed of an adhesive capable of adhering the base material layer 1 and the metal layer 3. The adhesive used for forming the adhesive layer 2 may be a two-component curable adhesive or a one-component curable adhesive. Furthermore, the adhesive mechanism of the adhesive 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 hot pressure type, and the like.

  Specific examples of adhesive components 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 copolyester; Ether adhesive; Polyurethane adhesive; Epoxy resin; Phenol resin resin; Polyamide resin such as nylon 6, nylon 66, nylon 12, copolymer polyamide; Polyolefin such as polyolefin, carboxylic acid modified polyolefin, metal modified polyolefin Resin, polyvinyl acetate resin; cellulose adhesive; (meth) acrylic resin; polyimide resin; amino resin such as urea resin and melamine resin; chloroprene rubber, nitrile rubber, styrene - rubbers such as butadiene rubber, silicone-based resins. These adhesive components may be used individually by 1 type, and may be used in combination of 2 or more type. Among these adhesive components, a polyurethane adhesive is preferable.

  The thickness of the adhesive layer 2 is not particularly limited as long as the battery packaging material satisfies the above physical properties while exhibiting the function as the adhesive layer. For example, the thickness is about 1 to 10 μm, preferably about 2 to 5 μm. It is done.

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

The aluminum foil used as the metal layer 3 has a 0.2% proof stress when a parallel tensile test is performed with respect to the MD direction and a 0.2% when a parallel tensile test is performed 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 the battery packaging material satisfies the above physical properties while exhibiting the function as the metal layer. For example, the thickness is about 10 μm to 50 μm, preferably about 20 μm to 40 μm. it can.

  The metal layer 3 is preferably subjected to chemical conversion treatment on at least one surface, preferably both surfaces, for the purpose of stabilizing adhesion, preventing 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 the metal layer. As the chemical conversion treatment, for example, chromate chromate using chromic acid compounds such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromic acetyl acetate, chromium chloride, potassium sulfate chromium, etc. Treatment; Phosphoric acid chromate treatment using a phosphoric acid compound such as sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid; aminated phenol having a repeating unit represented by the following general formulas (1) to (4) Examples include chromate treatment using a polymer.

In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ¹ and R ² are the same or different and each represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group. 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, an isobutyl group, C1-C4 linear or branched alkyl groups, such as a tert- butyl group, are mentioned. Examples of the hydroxyalkyl group 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, 3- C1-C4 straight or branched chain in which one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group is substituted An alkyl group is mentioned. In the general formulas (1) to (4), the alkyl group and hydroxyalkyl group represented by X, R ¹ and R ² may be the same or different. 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 units represented by the general formulas (1) to (4) is preferably, for example, 500 to 1,000,000, more preferably about 1,000 to 20,000. preferable.

  In addition, as a chemical conversion treatment method for imparting corrosion resistance to the metal layer 3, a metal oxide such as aluminum oxide, titanium oxide, cerium oxide, tin oxide, or barium sulfate fine particles dispersed in phosphoric acid is coated. 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 crosslinking a cationic polymer with a crosslinking agent may be further formed on the corrosion-resistant treatment layer. Here, examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, a primary amine graft acrylic resin obtained by graft polymerization of a primary amine on an acrylic main skeleton, and polyallylamine. Or the derivative, aminophenol, etc. are mentioned. As these cationic polymers, only one type may be used, or two or more types may be used in combination. Examples of the crosslinking agent include a compound having at least one functional group selected from the group consisting of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent. As these crosslinking agents, only one type may be used, or two or more types may be used in combination.

  As the chemical conversion treatment, only one type of chemical conversion treatment may be performed, or two or more types of chemical conversion treatment may be performed in combination. Furthermore, these chemical conversion treatments may be carried out using one kind of compound alone, or may be carried out using a combination of two or more kinds of compounds. Among the chemical conversion treatments, chromic acid chromate treatment, chromate treatment combining a chromic acid compound, a phosphoric acid compound, and an aminated phenol polymer 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. For example, if the above chromate treatment is performed, a chromic acid compound is present per 1 m ² of the surface of the metal layer 3. About 0.5 mg to about 50 mg, preferably about 1.0 mg to about 40 mg in terms of chromium, about 0.5 mg to about 50 mg, preferably about 1.0 mg to about 40 mg in terms of phosphorus, and aminated phenol weight It is desirable that the coalescence is contained at a ratio 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, an immersion method, or the like, and then the temperature of the metal layer is 70. It is carried out by heating so as to have a temperature of from about 0 to 200 ° C. Further, before the chemical conversion treatment is performed on the metal layer, the metal layer may be previously 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. 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 that seals the battery element by heat-sealing the sealant layers when the battery is assembled.

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

  Specific examples of the polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; homopolypropylene, polypropylene block copolymer (for example, block copolymer of propylene and ethylene), polypropylene And a random copolymer (for example, a random copolymer of propylene and ethylene); an ethylene-butene-propylene terpolymer; 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, and isoprene. Is mentioned. Examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkene is preferable, and norbornene is more preferable.

  The carboxylic acid-modified polyolefin is a polymer obtained by modifying the polyolefin by block polymerization or graft polymerization with carboxylic acid. Examples of the carboxylic acid used for modification 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 monomer constituting the cyclic polyolefin in place of the 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 an unsaturated carboxylic acid or its anhydride. The cyclic polyolefin to be modified with carboxylic acid is the same as described above. The carboxylic acid used for modification is the same as that used for modification of the acid-modified cycloolefin copolymer.

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

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

  The thickness of the sealant layer 4 is not particularly limited as long as the battery packaging material satisfies the above physical properties while exhibiting the function as a sealant layer. For example, the thickness is about 10 to 100 μm, preferably about 15 to 50 μm. Is mentioned.

[Adhesive layer 5]
In the battery packaging material of the present invention, the adhesive layer 5 is a layer provided between the metal layer 3 and the sealant layer 4 as necessary in order to firmly bond them.

  The adhesive layer 5 is formed of an adhesive capable of bonding the metal layer 3 and the sealant layer 4. With respect to the adhesive used for forming the adhesive layer 5, the adhesive mechanism, the types of adhesive components, and the like are the same as those of the adhesive layer 2. The adhesive component used for the adhesive layer 5 is preferably a polyolefin resin, more preferably a carboxylic acid-modified polyolefin, particularly preferably a carboxylic acid-modified polypropylene.

  The thickness of the adhesive layer 5 is not particularly limited as long as the battery packaging material satisfies the above physical properties while exhibiting the function as the adhesive layer. For example, the thickness is about 2 to 50 μm, preferably about 15 to 30 μm. It is done.

[Coating layer 6]
In the battery packaging material of the present invention, for the purpose of improving design properties, electrolytic solution resistance, scratch resistance, moldability, etc., the base material layer 1 may be formed on the base material layer 1 as necessary (the metal layer of the base material layer 1). If necessary, a coating layer 6 may be provided on the side opposite to 3. The coating layer 6 is a layer located in the outermost layer when the battery is assembled.

  The coating layer 6 can be formed of, for example, polyvinylidene chloride, polyester resin, urethane resin, acrylic resin, epoxy resin, or the like. Of these, the coating layer 6 is preferably formed of a two-component curable resin. Examples of the two-component curable resin that forms the coating layer 6 include a two-component curable urethane resin, a two-component curable polyester resin, and a two-component curable epoxy resin. The coating layer 6 may contain a matting agent.

  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 not particularly limited, and examples thereof include a spherical shape, a fiber shape, a plate shape, an indeterminate shape, and a balloon shape. Specific examples of the matting agent include talc, silica, graphite, kaolin, montmorilloid, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, and aluminum oxide. , Neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, High melting point nylon, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel and the like can be mentioned. These matting agents may be used individually by 1 type, and may be used in combination of 2 or more type. Among these matting agents, silica, barium sulfate, and titanium oxide are preferable from the viewpoint of dispersion stability and cost. The matting agent may be subjected to various surface treatments such as insulation treatment and high dispersibility treatment on the surface.

  The method for forming the coating layer 6 is not particularly limited, and examples thereof include a method of applying a two-component curable resin for forming the coating layer 6 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 6 is not particularly limited as long as the battery packaging material satisfies the above physical properties while exhibiting the above-described function as the coating layer 6, for example, about 0.5 to 10 μm, preferably 1 to For example, about 5 μm.

4). Method for Producing 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 layers having a predetermined composition are laminated is obtained. For example, the following method is exemplified. .

  First, a laminate in which the base material layer 1, the adhesive layer 2, and the metal layer 3 are laminated in order (hereinafter also 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 layer 1 or the metal layer 3 whose surface is subjected to chemical conversion treatment, if necessary. It can be performed 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 applied 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 laminate A. When the sealant layer 4 is directly laminated on the metal layer 3, the resin component constituting the sealant layer 4 may be applied on the metal layer 3 of the laminate A by a method such as a gravure coating method or a roll coating method. . In the case where 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 laminated on the metal layer 3 of the laminate A by coextrusion. (2) A method of separately forming a laminate in which the adhesive layer 5 and the sealant layer 4 are laminated, and laminating the laminate on the metal layer 3 of the laminate A by a thermal lamination method, 3) An adhesive for forming the adhesive layer 5 is laminated on the metal layer 3 of the laminate A by an extrusion method or a solution-coated high temperature drying and baking method, and a sheet-like shape is formed on the adhesive layer 5 in advance. (4) A melted adhesive layer 5 is placed between the metal layer 3 of the laminate A and the sealant layer 4 previously formed into a sheet shape. Adhesive layer 5 while pouring Method (sand lamination method) and the like to bond the laminate A and the sealant layer 4.

  When the coating layer 6 is provided, the coating layer 6 is laminated on the surface of the base material layer 1 opposite to the metal layer 3. The coating layer 6 can be formed by, for example, applying the above-described resin for forming the coating layer 6 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 6 on the surface of the base material layer 1 are not particularly limited. For example, after forming the coating layer 6 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 6.

  As described above, base material layer 1 / adhesive layer 2 / metal layer 3 whose surface is subjected to chemical conversion treatment as required / adhesive layer 5 provided as needed / sealant layer 4 / coating provided as needed In order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as necessary, a hot roll contact type, a hot air type, a near or far infrared type is further formed. You may use for heat processing. Examples of such heat treatment conditions include 150 to 250 ° C. for 1 to 5 minutes.

  In the battery packaging material of the present invention, each layer constituting the laminate improves or stabilizes film forming properties, lamination processing, suitability for final processing (pouching, embossing), etc., as necessary. Therefore, surface activation treatment such as corona treatment, blast treatment, oxidation treatment, ozone treatment may be performed.

5. Application of Battery Packaging Material The battery packaging material of the present invention is used as a packaging material for sealing and housing battery elements such as a positive electrode, a negative electrode, and an electrolyte.

  Specifically, a battery element including at least a positive electrode, a negative electrode, and an electrolyte is formed using the battery packaging material of the present invention, with the metal terminals connected to each of the positive electrode and the negative electrode protruding outward. A battery using a battery packaging material is formed by covering the periphery of the element so that a flange portion (a region where the sealant layers are in contact with each other) can be formed, and heat-sealing and sealing the sealant layers of the flange portion. Provided. In addition, when accommodating a battery element using the battery packaging material of the present invention, the battery packaging material of the present invention is used such that the sealant portion is on the inner side (surface in contact with the battery element).

  The battery packaging material of the present invention may be used for either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery to which the battery packaging material of the present invention is applied is not particularly limited. For example, a lithium ion battery, a lithium ion polymer battery, a lead battery, a nickel / hydrogen battery, a nickel / cadmium battery , Nickel / iron livestock batteries, nickel / zinc livestock batteries, silver oxide / zinc livestock batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors and the like. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the battery packaging material of the present invention.

  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.

Example 1-8 and Comparative Example 1-4
<Manufacture of battery packaging materials>
By laminating the adhesive layer 5 and the sealant layer 4 by the thermal laminating method on the laminate in which the base material layer 1 / adhesive layer 2 / metal layer 3 are laminated in order, the base material layer 1 / adhesive layer 2 / metal A battery packaging material comprising a laminate in which layer 3 / adhesive layer 5 / sealant layer 4 were sequentially laminated was produced. Details of each layer constituting the packaging material for the battery and manufacturing conditions are as follows.

<Base material layer 1>
Details of nylon-A, nylon-B, polybutylene terephthalate A (PBT-A), polybutylene terephthalate B (PBT-B), and polyethylene terephthalate (PET) used as the base material layer 1 are shown below. In addition, the tensile breaking strength and the tensile breaking elongation shown in Table 1 are values measured by a method based on JIS K7127, respectively.

(Nylon-A, -B)
An unstretched raw film made of a raw material mainly composed of nylon 6 is manufactured by simultaneous biaxial stretching by a tubular method and then heat-treating at 200 ° C. Nylon-A has a draw ratio of 3.0 times in the flow direction (MD) and 3.3 times in the width direction (TD). Nylon-B has a draw ratio of 2.8 times in the flow direction (MD) and the width direction. (TD) Manufactured under conditions of 3.0 times.

(PBT-A, -B)
An unstretched raw film made of a raw material mainly composed of a resin obtained by adding 8% by weight of polyethylene terephthalate to polybutylene terephthalate is manufactured by simultaneously biaxially stretching by a tubular method and then heat-treating at 205 ° C. . PBT-A has a draw ratio of 3.8 times in the flow direction (MD) and 3.8 times in the width direction (TD). PBT-B has a draw ratio of 3.0 times in the flow direction (MD) and the width direction. (TD) Manufactured under conditions of 3.0 times.

(PET)
An unstretched raw film made of a raw material containing polyethylene terephthalate as a main component is manufactured by sequentially biaxially stretching by a tenter method and then heat-treating at 210 ° C. PET was produced under the conditions that the draw ratio was 3.2 times in the flow direction (MD) and 3.2 times in the width direction (TD).

<Metal layer 3>
The aluminum foil (ALM1: 8021 material, ALM2: 8079 material, ALM3: 1N30 material) which has the physical property shown in the following Table 2 was used, respectively. The tensile rupture strength and the tensile rupture elongation are values measured by methods based on JIS K7127, respectively. The 0.2% proof stress is a value measured by a tensile test specified in JIS Z 2241.

<Adhesive layer 2>
As the adhesive layer 2 for adhering the base material layer 1 and the metal layer 3, the following adhesive A and adhesive B were used.
(Adhesive A)
A trimethylolpropane (TMP) adduct of a polyol compound and toluene diisocyanate (TDI) having a glass transition point of -5 to 5 ° C., a weight average molecular weight of 10 to 40 × 10 3, and a hydroxyl group equivalent of 0.7 to 1.9 / mol. A urethane resin adhesive in which aromatic isocyanate as a main component was mixed at a ratio of 1: 3 was used.
(Adhesive B)
Mainly composed of a polyol compound having a glass transition point of 15 to -5 ° C., a weight average molecular weight of 10 to 10 × 10 3 and a hydroxyl group equivalent of 0.7 to 1.9 / mol and an isocyanurate modified product of toluene diisocyanate (TDI). A urethane resin adhesive in which an aromatic isocyanate to be mixed at a ratio of 1: 3 was used.

<Coating layer 6>
It is the layer formed in Example 8 for the purpose of improving the moldability of the battery packaging material. The coating layer 6 is formed by applying an epoxy resin having bisphenol A as a unit in the skeleton on the substrate layer 1 at a coating amount of 2.5 g / m ² , drying, and heating at 190 ° C. for 2 minutes to cure. Formed as a film.

  Using each of the above layers, first, a laminate in which the base material layer 1 / adhesive layer 2 / metal layer 3 were laminated in order was produced. Specifically, an adhesive layer 2 composed of a polyester main agent and an isocyanic curing agent two-component urethane adhesive is formed on one surface (corona-treated surface) of the base material layer 1 so as to have a thickness of 3 μm. A layered product in which the base material layer 1 / adhesive layer 2 / metal layer 3 were laminated in this order was prepared by pressure-heat bonding with the chemical conversion treatment surface of the layer 3.

  Separately, an acid-modified polypropylene resin constituting the adhesive layer 5 [an unsaturated carboxylic acid graft-modified random polypropylene grafted with an unsaturated carboxylic acid (hereinafter referred to as PPa) and a polypropylene constituting the sealant layer 4 [random Copolymer (hereinafter referred to as PP)] was coextruded to produce a two-layer coextruded film comprising the adhesive layer 5 and the sealant layer 4.

Next, the metal layer 3 was laminated so that the adhesive layer 5 of the two-layer coextruded film prepared above was in contact with the metal layer of the laminate composed of the base material layer 1 / adhesive layer 2 / metal layer 3 prepared above. Was heated to 120 ° C. and thermal lamination was performed to obtain a laminate in which base layer 1 / adhesive layer 2 / metal layer 3 / adhesive layer 5 / sealant layer 4 were laminated in this order. After cooling the obtained laminated body once, it heated until it became 180 degreeC, the temperature was hold | maintained for 1 minute, and it heat-processed, and the packaging material for batteries of Example 1-8 and Comparative Example 1-4 was used. Obtained. In Example 8, the coating layer 6 was formed on the surface of the base material layer 1 of the obtained laminate, and a battery packaging material was obtained.

Example The laminated structure of the battery packaging materials produced in Example 1-8 and Comparative Example 1-4 and the thickness of each layer are as follows.
Example 1
Nylon-A (25 μm) / Adhesive A (3 μm) / ALM1 (40 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (20 μm)
(Example 2)
Nylon-A (25 μm) / Adhesive A (3 μm) / ALM1 (50 μm) / Adhesive layer 5 (30 μm) / Sealant layer 4 (30 μm)
(Example 3)
Nylon-A (15 μm) / Adhesive A (3 μm) / ALM1 (35 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (20 μm)
Example 4
Nylon-A (15 μm) / Adhesive A (3 μm) / ALM2 (35 μm) / Adhesive layer 5 (15 μm) / Sealant layer 4 (15 μm)
(Example 5)
PBT-A (20 μm) / Adhesive A (3 μm) / ALM1 (40 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (20 μm)
(Example 6)
PET (12 μm) / Adhesive A (3 μm) / Nylon A (15 μm) / Adhesive A (3 μm) / ALM1 (40 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (20 μm)
(Example 7)
Nylon-B (25 μm) / Adhesive B (3 μm) / ALM1 (40 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (20 μm)
(Example 8)
Coating layer 6 (2 μm) / nylon-B (25 μm) / adhesive A (3 μm) / ALM1 (40 μm) / adhesive layer 5 (20 μm) / sealant layer 4 (20 μm)
(Comparative Example 1)
Nylon-B (25 μm) / Adhesive A (3 μm) / ALM1 (40 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (20 μm)
(Comparative Example 2)
PBT-B (12 μm) / Adhesive A (3 μm) / ALM1 (40 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (20 μm)
(Comparative Example 3)
PET (12 μm) / Adhesive A (3 μm) / ALM1 (40 μm) / Adhesive layer 5 (20 μm) / Sealant layer 4 (20 μm)
(Comparative Example 4)
Nylon-A (15 μm) / Adhesive A (3 μm) / ALM3 (35 μm) / Adhesive layer 5 (15 μm) / Sealant layer 4 (15 μm)

<Measurement of tensile breaking strength and tensile breaking elongation>
The 40% elongation stress and 10% elongation stress in the MD direction and the TD direction of the battery packaging material obtained above were measured by methods in accordance with the provisions of JIS K7127, respectively. The measurement conditions were a sample width of 15 mm, a distance between marked lines of 50 mm, and a tensile speed of 100 mm / min. The results are shown in Table 3.

<Evaluation of formability>
The battery packaging material obtained above was cut into 120 × 80 mm strips, which were used as test samples. Using a straight mold composed of a 30 × 50 mm rectangular male mold and a female mold with a clearance of 0.5 mm between the male mold and the above, the thermal adhesive resin layer side is positioned on the male mold side. The test sample was placed, and the test sample was pressed with a presser pressure (surface pressure) of 0.1 MPa so as to have a forming depth of 6 mm and 7 mm, respectively, and cold-formed (one-step drawing). The presence or absence of pinholes and cracks in the metal layer in the molded battery packaging material was confirmed, and the pinhole and crack generation rates (%) were calculated. The rate of occurrence of pinholes and cracks was determined when molding was performed when 30 test samples were molded under the above conditions, with pinholes or cracks observed even at one location after molding as a defective molding. Calculated as the percentage of defective products. The results are shown in Table 3.

  As is apparent from the results shown in Table 3, the battery of Example 1-8 using a battery packaging material satisfying A + B ≧ 2.50 even when molded under a severe condition of a molding depth of 6 mm. In the packaging material, pinholes and cracks were not seen at all, and the occurrence of pin poles and cracks could be remarkably suppressed. In particular, in Example 1-3 that satisfies A + B ≧ 2.65 as a battery packaging material, even when molded under a more severe condition of a molding depth of 7 mm, pinholes and cracks are not seen at all. The occurrence of cracks was remarkably suppressed. On the other hand, when the battery packaging material of Comparative Example 1-4 using A + B <2.50 as the battery packaging material was formed at a molding depth of 6 mm, the incidence of pinholes and cracks was high. The moldability was inferior to that of -8.

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

Claims (7)

It consists of a laminate in which at least a base material layer, an adhesive layer, a metal layer, and a sealant layer are sequentially laminated,
The base material layer includes at least one of a polyamide resin and a polyester resin,
The metal layer is an aluminum foil provided with an acid-resistant film on at least one surface,
The sealant layer is a polyolefin;
The laminate has a value A obtained by dividing a stress value at 40% elongation in the MD direction by a stress value at 10% elongation in the MD direction, and a stress value at 40% elongation in the TD direction as 10% in the TD direction. A battery packaging material in which the sum (A + B) of the value B divided by the stress value at% elongation satisfies the relationship of A + B ≧ 2.50.   The battery packaging material according to claim 1, wherein the A and the B satisfy a relationship of A <B.   The battery packaging material according to claim 1, wherein the A is A ≧ 1.19, and the B is B ≧ 1.31.   The tensile strength at break in the MD direction and TD direction of the base material layer is both 200 MPa or more, and the tensile elongation at break in the MD direction and TD direction of the base material layer is both in the range of 70 to 130%. The battery packaging material according to claim 1. The metal layer has both a 0.2% proof stress when a tensile test in a parallel direction with respect to the MD direction and a 0.2% proof stress when a tensile test in a parallel direction with respect to the TD direction are performed. The battery packaging material according to claim 1, which is an aluminum foil in a range of ˜140 N / mm ² . The battery packaging material according to any one of claims 1 to 5 , which is a packaging material for a secondary battery. At least a positive electrode, a negative electrode, and a battery device having an electrolyte is housed in the battery packaging the material according to any one of claims 1 to 6 battery.