JP6264419B2 - Battery packaging materials - Google Patents

Description

  The present invention relates to a battery packaging material that can suppress the occurrence of a short circuit between a battery electrode and a metal layer of a packaging material by heat sealing at the time of sealing, and further suppress the occurrence of cracks.

  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. In such a film-like laminate, polyethylene or polypropylene, which is a crystalline thermoplastic resin, is generally used as the sealant layer (see, for example, Patent Document 1). However, when polyethylene or polypropylene is used as the sealant layer, the crystalline polyethylene or polypropylene is excessively crushed during heat sealing when sealing the battery element, causing a short circuit between the battery electrode and the metal layer of the packaging material. There is a problem that it becomes easy.

  Furthermore, since polyethylene and polypropylene are crystalline, when they are used in the sealant layer, there is a problem that cracks are likely to occur for the following reasons: (1) The film is stretched because it is crystalline. Cracks are likely to occur during molding. (2) After sealing the battery element (after heat sealing), the crystallinity cannot be managed in the cooling stage, so cracks are particularly likely to occur during folding of the seal part. (3) For batteries In the heat treatment during the manufacturing process of the packaging material or battery, the sealant layer may be heated to a temperature higher than the melting point of polyethylene or polypropylene, and it is difficult to manage the crystallinity in the cooling process, and cracks are likely to occur. ) When foreign matter is mixed into the sealant layer, crazes (cracks) are likely to occur along the crystal part starting from the foreign matter. Thus, when a crack arises in the battery packaging material, the electrolytic solution penetrates into the metal layer to form a metal deposit, and as a result, a short circuit may occur.

  Against the background of such conventional technology, in the battery packaging material composed of a film-like laminate, the battery electrode and the metal layer of the packaging material are provided by heat sealing at the time of sealing while having the basic performance required as a battery packaging material. The development of a technique that prevents short circuit between the two and further suppresses the generation of cracks is eagerly desired.

JP2012-014998A

  The present invention provides a technique for preventing a short circuit between a battery electrode and a metal layer of a packaging material by heat sealing at the time of sealing in a battery packaging material composed of a laminate, and further suppressing the occurrence of cracks. The purpose is to provide.

  The present inventor conducted intensive studies to solve the above problems, and in the battery packaging material comprising a laminate in which at least a base material layer, a metal layer, an adhesive resin layer, and a sealant layer are sequentially laminated, When the adhesive resin layer contains a carboxylic acid-modified polyolefin and the sealant layer contains a cycloolefin copolymer made of a copolymer of ethylene and norbornene, the battery electrode and the metal layer of the packaging material are sealed by heat sealing at the time of sealing. It was found that a short circuit occurring between the two can be prevented and the occurrence of cracks in the packaging material can be suppressed. The present invention has been completed by further studies based on such knowledge.

That is, this invention provides the battery packaging material and battery of the aspect hung up below.
Item 1. At least a base material layer, a metal layer, an adhesive resin layer, and a sealant layer are sequentially laminated. The adhesive resin layer contains a carboxylic acid-modified polyolefin, and the sealant layer is a copolymer of ethylene and norbornene. A battery packaging material comprising a cycloolefin copolymer comprising:
Item 2. Item 2. The sealant layer is formed of a blend polymer including (i) the cycloolefin copolymer and (ii) at least one selected from the group consisting of polyolefin and carboxylic acid-modified polyolefin. Battery packaging material.
Item 3. Item 3. The battery packaging material according to Item 1 or 2, wherein the carboxylic acid-modified polyolefin forming the adhesive resin layer is carboxylic acid-modified polyethylene or carboxylic acid-modified polypropylene.
Item 4. Item 4. The battery packaging material according to any one of Items 1 to 3, wherein the metal layer is aluminum.
Item 5. Item 5. The battery packaging material according to any one of Items 1 to 4, wherein a chemical conversion treatment is applied to at least one surface of the metal layer.
Item 6. Item 6. The battery packaging material according to any one of Items 1 to 5, which is a packaging material for a secondary battery.
Item 7. Item 7. 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 6.

  According to the battery packaging material of the present invention, the battery element is less crushed by heat sealing when the battery element is sealed, so that a short circuit occurring between the battery electrode and the metal layer of the packaging material can be prevented.

  Moreover, since the sealant layer in the battery packaging material of the present invention includes a cycloolefin copolymer composed of a copolymer of ethylene and norbornene and is an amorphous layer, it is possible to suppress the occurrence of cracks. Furthermore, even if a crack occurs in the sealant layer, the sealant layer is amorphous, so that the crack can be prevented from becoming large, and the electrolytic solution can penetrate into the metal layer to form metal deposits. As a result, it is possible to suppress the occurrence of a short circuit inside the battery.

  In addition, the battery packaging material of the present invention has excellent characteristics such as durability (ability to suppress delamination by the electrolyte), water vapor barrier properties, and heat resistance (ability to suppress thermal burst of the sealed portion after heat sealing). The basic performance required as a battery packaging material can also be satisfied.

It is a figure which shows an example of the cross-section of the packaging material for batteries of this invention.

  The battery packaging material of the present invention comprises a laminate in which at least a base material layer, a metal layer, an adhesive resin layer, and a sealant layer are sequentially laminated, and the adhesive resin layer contains a carboxylic acid-modified polyolefin, and the sealant The layer is characterized in that it comprises a cycloolefin copolymer consisting of a copolymer of ethylene and norbornene. 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, a metal layer 2, an adhesive resin 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.

  Moreover, in the battery packaging material of the present invention, an adhesive resin layer may be provided between the base material layer 1 and the metal layer 2 as necessary for the purpose of enhancing these adhesive properties. Hereinafter, the adhesive resin layer 3 provided between the metal layer and the sealant layer is referred to as “adhesive resin layer A”, and the adhesive resin layer provided as necessary between the base material layer and the metal layer is “adhered”. It may be described as “resin layer B”.

2. Composition of each layer forming the battery packaging material [base material layer]
In the battery packaging material of the present invention, the base material layer is a layer forming the outermost layer. The material for forming the base material layer is not particularly limited as long as it has insulating properties. Examples of the material for forming the base material layer include polyester resin, polyamide resin, epoxy resin, acrylic resin, fluorine resin, polyurethane resin, silicon resin, phenol resin, and mixtures and copolymers thereof. 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 such as nylon 6,10, and polymetaxylylene adipamide (MXD6). Etc. Among these, preferably nylon and polyester, more preferably biaxially stretched nylon, biaxially stretched polyester, and particularly preferably biaxially stretched polyester.

  The base material layer may be formed of one resin layer, but may be formed of two or more resin layers in order to improve pinhole resistance and insulation. When the base material layer is formed of two or more resin layers, as a specific example of the base material layer, a multilayer structure in which a resin layer made of polyester and a resin layer made of nylon are laminated, preferably biaxially stretched polyester And a multilayer structure in which a resin layer made of biaxially stretched nylon is laminated. When making a base material layer into a multilayer structure, two or more resin layers should just be laminated via an adhesive, and the type and amount of the adhesive used are the case of the adhesive resin layer B described later. It is the same.

  About the thickness of a base material layer, 10-50 micrometers, for example, Preferably 15-30 micrometers is mentioned.

[Adhesive resin layer B]
In the battery packaging material of the present invention, the adhesive resin layer B is a resin layer provided as necessary between the base material layer and the metal layer.

  The adhesive resin layer B is formed of an adhesive that can bond the base material layer and the metal layer. The adhesive used for forming the adhesive resin layer B may be a two-component curable adhesive or a one-component curable adhesive. Furthermore, the bonding mechanism of the adhesive used for forming the adhesive resin layer B 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 the adhesive component that can be used to form the adhesive resin layer B include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolyester. Polyether adhesive; polyurethane adhesive; epoxy resin; phenol resin resin; polyamide resin such as nylon 6, nylon 66, nylon 12, copolymer polyamide; polyolefin, carboxylic acid modified polyolefin, metal modified polyolefin, etc. 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. The combination mode of two or more kinds of adhesive components is not particularly limited. For example, as the adhesive components, mixed resin of polyamide and carboxylic acid-modified polyolefin, mixed resin of polyamide and metal-modified polyolefin, polyamide and polyester And a mixed resin of polyester and carboxylic acid-modified polyolefin, a mixed resin of polyester and metal-modified polyolefin, and the like. Among these, Preferably a polyurethane type 2 liquid-curing-type adhesive; Polyamide, polyester, or blend resin of these and carboxylic acid modification polyolefin is mentioned.

  The thickness of the adhesive resin layer B is, for example, 2 to 10 μm, preferably 3 to 6 μm.

[Metal layer]
In the battery packaging material of the present invention, the metal layer is a layer that functions as a barrier layer for preventing the penetration of water vapor, oxygen, light, etc. into the battery, in addition to improving the strength of the packaging material. Specific examples of the metal forming the metal layer include metal foils such as aluminum, stainless steel, and titanium. Among these, aluminum is preferably used. In order to prevent wrinkles and pinholes during the production of the packaging material, it is possible to use soft aluminum, for example, annealed aluminum (JIS A8021P-O) or (JIS A8079P-O) as the metal layer in the present invention. preferable.

  About the thickness of a metal layer, 10-100 micrometers is mentioned, for example, Preferably 20-50 micrometers is mentioned.

  Further, the metal layer is subjected to chemical conversion treatment on at least one surface, preferably at least the surface in contact with the adhesive resin layer A, and more preferably both surfaces in order to stabilize adhesion, prevent dissolution, impart corrosion resistance, and the like. Is preferred.

  Here, the chemical conversion treatment is a treatment for forming an acid-resistant film on the surface of the metal layer. Chemical conversion treatment is, for example, chromate chromate treatment using a chromic acid compound such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromic acetyl acetate, chromium chloride, potassium sulfate chromium, etc. ; Phosphoric acid chromate treatment using phosphoric acid compounds such as sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid; aminated phenol heavy consisting of repeating units represented by the following general formulas (1) to (4) Examples thereof include chromate treatment using a coalescence.

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 represent 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- A linear or branched chain having 1 to 4 carbon atoms substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group An alkyl group is mentioned. be able to. In the general formulas (1) to (4), X is preferably any one of a hydrogen atom, a hydroxyl group, and a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer composed of the repeating units represented by the general formulas (1) to (4) is, for example, about 500 to about 1,000,000, preferably about 1000 to about 20,000.

  Further, as a chemical conversion treatment method for imparting corrosion resistance to the metal layer, a coating in which phosphoric acid is dispersed with metal oxides such as aluminum oxide, titanium oxide, cerium oxide, tin oxide and the like and fine particles of barium sulfate is coated. A method of forming a corrosion-resistant treatment layer on the surface of the metal layer by performing a baking treatment at a temperature of 0 ° C. or higher can be mentioned. A resin layer obtained by crosslinking a cationic polymer with a crosslinking agent may be formed on the corrosion-resistant treatment layer. Here, as the cationic polymer, for example, polyethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is grafted on an acrylic main skeleton, polyallylamine, or Examples thereof include aminophenols and derivatives thereof. These cationic polymers may be used individually by 1 type, and may be used in combination of 2 or more type. Examples of the crosslinking agent include compounds having at least one functional group selected from the group consisting of isocyanate groups, glycidyl groups, carboxyl groups, and oxazoline groups, silane coupling agents, and the like. These crosslinking agents may be used alone or in combination of two or more.

  These chemical conversion treatments may be performed alone or in combination of two or more chemical conversion treatments. 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 these, chromic acid chromate treatment is preferable, and chromate treatment in which a chromic acid compound, a phosphoric acid compound, and the aminated phenol polymer are combined is more preferable.

The amount of the acid-resistant film to be formed on the surface of the metal layer in the chemical conversion treatment is not particularly limited. For example, if the chromate treatment is performed by combining a chromic acid compound, a phosphoric acid compound, and the aminated phenol polymer, for example. The chromic acid compound is about 0.5 to about 50 mg, preferably about 1.0 to about 40 mg in terms of chromium, and the phosphorus compound is about 0.5 to about 50 mg in terms of phosphorus per 1 m ² of the surface of the metal layer, preferably About 1.0 to about 40 mg, and the aminated phenol polymer is desirably contained in an amount of about 1 to about 200 mg, preferably about 5.0 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 to about 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 perform the chemical conversion treatment of the surface of the metal layer more efficiently.

[Adhesive resin layer A]
In the battery packaging material of the present invention, the adhesive resin layer A is a layer that firmly bonds the metal layer and a sealant layer described later.

  In the present invention, the adhesive resin layer A is composed of a resin layer containing a carboxylic acid-modified polyolefin. Thus, by using the carboxylic acid-modified polyolefin for the adhesive resin layer A, in addition to the strong adhesion between the metal layer and the sealant layer described later, the battery electrode and the electrode of the battery are sealed by heat sealing when sealing the battery element. It is possible to prevent the metal layer of the packaging material from being short-circuited and further suppress the occurrence of cracks.

Carboxylic acid-modified polyolefin means that a part of the monomer constituting the polyolefin is copolymerized in place of α, β-unsaturated carboxylic acid or its anhydride, or α, β-unsaturated carboxylic acid with respect to polyolefin. It is a polymer obtained by block polymerization or graft polymerization of an acid or its anhydride.
Examples of the α, β-unsaturated carboxylic acid or anhydride thereof used for carboxylic acid modification include α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms or anhydrides thereof, and more specifically. Maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like. Among these, modification with maleic anhydride is preferable because it can ensure adhesion with a metal layer that is stable for a long period of time and is suitable for mass production.

  Examples of the carboxylic acid-modified polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; crystalline or amorphous polypropylene; ethylene-α olefin copolymer; propylene -Α olefin copolymer; trimethylpentene; ethylene-butene-propylene terpolymer, and the like. Among these, Preferably, polyethylene and polypropylene are mentioned.

  The melt flow rate (MFR) of the carboxylic acid-modified polyolefin used in the adhesive resin layer A is not particularly limited. For example, as MFR measured under the conditions of 190 ° C. and a load of 21.18 N described in JIS K 6922, 0.5 to 50 g / 10 min, preferably 1.0 to 20 g / 10 min.

  In the adhesive resin layer A, the carboxylic acid-modified polyolefin may be used alone or in combination of two or more.

  The carboxylic acid-modified polyolefin used in the adhesive resin layer A is preferably carboxylic acid-modified, from the viewpoint of more effectively exhibiting the action of preventing short circuit inside the battery by heat sealing and the action of suppressing the generation of cracks. Examples thereof include polyethylene and carboxylic acid-modified polypropylene, more preferably maleic anhydride-modified polyethylene and maleic anhydride-modified polypropylene.

  The adhesive resin layer A is preferably a resin layer composed of a carboxylic acid-modified polyolefin. However, as long as the effects of the present invention are not hindered, the adhesive resin layer A is a crystalline or amorphous polyolefin, cyclic polyolefin, ethylene-propylene-butene. In addition, other resin components such as polymethylpentene may be contained.

  About the thickness of the adhesive resin layer A, 3-50 micrometers, for example, Preferably 10-30 micrometers is mentioned.

[Sealant layer]
In the battery packaging material of the present invention, the sealant layer 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.

  In the present invention, the sealant layer is composed of a resin layer containing a cycloolefin copolymer made of a copolymer of ethylene and norbornene.

  As a ratio of ethylene and norbornene constituting the cycloolefin copolymer, for example, ethylene / norbornene (molar ratio) is about 70/30 to 20/80, preferably about 65/35 to 25/75, and more preferably 60 / 40 to about 30/70.

  A suitable example of the cycloolefin copolymer is one having a glass transition temperature of 65 to 210 ° C, preferably 75 to 190 ° C. By using a cycloolefin copolymer having such a glass transition temperature, excessive crushing of the sealant layer in the heat seal thermocompression treatment can be more effectively prevented, and the short-circuit prevention effect can be more effectively exhibited. Is possible. In addition, norbornene makes the sealant layer amorphous and can exhibit toughness, so that cracks in stretching, cracks in heat seal, cracks in bending processing of the seal portion, etc. can be more effectively prevented. Become. In addition, when a cycloolefin copolymer having the glass transition temperature is used, heat resistance and toughness are improved, the burst temperature (heat burst temperature) due to thermal expansion after sealing is increased, and the properties of the sealant layer are further improved. be able to.

  The MFR (melt flow rate) of the cycloolefin copolymer is not particularly limited. For example, the MFR measured under the conditions of 190 ° C. and a load of 21.18 N described in JIS K 6922 is 0.01 to 20 g / 10 minutes, Preferably 1.5-10 g / 10min is mentioned.

  The number average molecular weight of the cycloolefin copolymer is not particularly limited, and examples thereof include 15000 to 200000, preferably 20000 to 100000. Here, an average molecular weight shows the number average molecular weight measured by GPC. Moreover, as a weight molecular weight, it is 20000-400000, Preferably 30000-200000 is mentioned, for example. Furthermore, the molecular weight distribution (weight molecular weight / number average molecular weight) is, for example, 1.0 to 5.0, preferably 1.0 to 3.0. The average molecular weight, weight molecular weight, and molecular weight distribution shown here are values measured by GPC.

  Further, the cycloolefin copolymer is preferably copolymerized using a metallocene catalyst. A cycloolefin copolymer copolymerized using a metallocene catalyst has a uniform molecular weight distribution, little side chain branching, a tough and stable glass transition temperature, and enables a good heat seal. There is an advantage that the heat-resistant burst temperature that bursts due to thermal expansion also increases. When the sealant layer is formed from a blend polymer of the cycloolefin copolymer and polyethylene or polypropylene, the cycloolefin copolymer copolymerized using a metallocene catalyst has good compatibility with polyethylene and polypropylene and is uniform. Various blended resins can be formed. If the resin to be blended is poorly compatible, cracking at the interface is likely to occur when stretched, and peeling at the interface is likely to occur due to heat at the time of sealing. Folding after heat sealing or cooling However, by using a cycloolefin copolymer copolymerized with a metallocene catalyst, these disadvantages when forming a blend resin can be eliminated.

  The sealant layer may be formed only from the cycloolefin copolymer, but may be formed from a blend resin including the cycloolefin copolymer and other resin components. A suitable example of such a blend resin is a blend resin of the cycloolefin copolymer and a polyolefin and / or a carboxylic acid-modified polyolefin.

  The sealant layer may be a single layer of the cycloolefin copolymer or a blend of different melt flow rate, number molecular weight or molecular weight distribution, a single layer of a blend resin containing the other resin components, or a resin used for the blend resin. Can be used.

  In addition, the thickness of the sealant layer can be selected as appropriate, and is, for example, 2 to 2000 μm, preferably 5 to 1000 μm, and more preferably 10 to 500 μm. When the sealant layer is multilayered, the thickness of the layer formed only from the cycloolefin copolymer or the layer formed from a blend resin containing the cycloolefin copolymer and another resin component is, for example, 0. .3 to 1500 μm, preferably 0.5 to 1000 μm, more preferably 1 to 400 μm.

  Specific examples of the polyolefin used as one component of the blend resin include polyethylenes such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; block copolymers of homopolypropylene polypropylene (for example, propylene and Ethylene block copolymer), polypropylene random copolymer (eg, propylene and ethylene random copolymer) or other crystalline polypropylene; ethylene-butene-propylene terpolymer; polymethylpentene; cyclic olefin, etc. .

  Further, suitable examples of the carboxylic acid-modified polyolefin used as one component of the blend resin and the carboxylic acid-modified polyolefin are the same as those used in the adhesive resin layer A.

  Among the resin components other than the cycloolefin copolymer used in the blend resin, the action of preventing a short circuit that occurs inside the battery by heat sealing, the action of suppressing the generation of cracks, and the action of increasing the heat-resistant burst temperature are more effective. From the viewpoint of exerting, preferably, polyethylene, crystalline or amorphous polypropylene, carboxylic acid-modified polyethylene, carboxylic acid-modified polypropylene, ethylene-butene-propylene terpolymer, polymethylpentene, and cyclic olefin are exemplified.

  When the sealant layer is formed from a blend resin containing the cycloolefin copolymer and other resin components, the ratio of these resins is not particularly limited, but for example, other resin components per 10 parts by mass of the cycloolefin copolymer. 1 to 90 parts by mass, preferably 3 to 40 parts by mass.

3. 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 metal layer whose surface is subjected to chemical conversion treatment as necessary is laminated on a base material. In the case where a metal layer whose surface is subjected to a chemical conversion treatment is directly laminated on a base material, a method of thermocompression bonding the base material and the metal layer heated in advance is exemplified. In addition, when a metal layer having a surface subjected to chemical conversion treatment is laminated on the base material via the adhesive resin layer B, a resin component that forms the adhesive resin layer B on the base material or the metal layer is added. After applying and drying by a coating method such as a gravure coating method and a roll coating method, it can be performed by a dry lamination method in which the metal layer or substrate is laminated and the adhesive resin layer B is cured. Thus, a base material / adhesive resin layer B provided as necessary / a laminated body made of a metal layer whose surface is subjected to chemical conversion treatment as needed (hereinafter sometimes referred to as “laminate A”). can get.

Next, the adhesive resin layer A and the sealant layer are sequentially laminated on the metal layer of the laminate A. As a method of laminating the adhesive resin layer A and the sealant layer, for example, (1) a method of laminating the adhesive resin layer A and the sealant layer on the metal layer of the laminate A by coextrusion (coextrusion lamination method) (2) Separately, a laminate in which the adhesive resin layer A and the sealant layer are laminated is formed, and this is laminated on the metal layer of the laminate A by a thermal nation method. (3) On the metal layer of the laminate A In addition, the resin component of the adhesive resin layer A is laminated by an extrusion method or a solution-coated high temperature drying and baking method, and a sealant layer previously formed into a sheet shape is laminated on the adhesive resin layer A by a thermal nation method. (4) While the molten adhesive resin layer A is poured between the metal layer of the laminated body A and the sealant layer previously formed into a sheet shape, the laminated body A and The method of bonding the Zealand layer (sand lamination method), (5) the method in which bonding in combination from (1) (4) below.

  As described above, a base material / adhesive resin layer B provided as necessary / a laminate composed of a metal layer whose surface is subjected to a chemical conversion treatment as necessary / a laminate composed of an adhesive resin layer A / a sealant layer is formed. However, in order to strengthen the adhesion by the adhesive resin layer B and the adhesive resin layer A provided as necessary for the laminate, further, a hot roll contact type, a hot air type, a near or far infrared type, etc. You may use for heat processing. Examples of such heat treatment conditions include 150 to 210 ° C. and 1 to 10 seconds.

4). 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.

Examples 1-9 and Comparative Examples 1-3
In the laminate in which the base material layer / adhesive resin layer B / metal layer are sequentially laminated, the adhesive layer resin A and the sealant layer are formed by any one of the thermal lamination method, the sand lamination method, and the dry lamination method, A battery packaging material was produced. The manufacturing conditions of the battery packaging material are as follows.

<Formation of laminate in which base material layer / adhesive resin layer B / metal layer are laminated in sequence>
Biaxially stretched polyethylene terephthalate having a thickness of 12 μm was used as the base material layer 1, and biaxially stretched nylon having a thickness of 15 μm was used as the base material layer 2. Moreover, as a metal layer, what carried out the chemical conversion treatment of both surfaces of 40-micrometer-thick aluminum (JIS8021 type | system | group) was used. For the chemical conversion treatment of the metal layer, a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid is applied to both surfaces of the metal layer by a roll coating method and baked for 20 seconds under the condition that the film temperature is 180 ° C. or higher. It went by.

The lamination of the base material layer 1 and the base material layer 2, and the lamination of the base material layer (laminated body of the base material layer 1 / base material layer 2) and the metal layer were laminated by a dry lamination method. Specifically, an adhesive resin layer composed of a polyester main agent and an isocyanic curing agent two-component urethane adhesive is formed on the base layer 1 so as to have a thickness of 4 μm. After pressure heating and bonding, an aging treatment was performed at 60 ° C. for 24 hours to obtain a base material layer (base material layer 1 / base material layer 2 laminate). On the base material layer 2 side of the base material layer, an adhesive resin layer B composed of a polyester main agent and a two-component urethane adhesive of an isocyanic curing agent is formed to a thickness of 4 μm, and the chemical conversion treatment surface of the metal layer After being bonded with pressure and heating, the laminate was subjected to an aging treatment at 60 ° C. for 48 hours, and a base material layer (base material layer 1 / base material layer 2) / adhesive resin layer B / metal layer was sequentially laminated. Got.

<Manufacture of battery packaging materials>
In Examples 1 to 4, the adhesive resin layer A and the sealant layer are bonded to the metal layer (chemically treated surface) of the laminate composed of the base material layer / adhesive resin layer B / metal layer by a thermal lamination method. Thus, a laminate composed of a base material layer / adhesive resin layer B / metal layer / adhesive resin layer A / sealant layer was formed.

  In Examples 5 to 7 and Comparative Example 1, the adhesive resin layer A and the sealant layer are used together on the metal layer (chemically treated surface) of the laminate composed of the base material layer / adhesive resin layer B / metal layer. Lamination was performed by an extrusion method to form a laminate composed of base material layer / adhesive resin layer B / metal layer / adhesive resin layer A / sealant layer.

  In Examples 8 and 9 and Comparative Example 2, a film in which a sealant layer was previously formed was prepared, and a metal layer (chemically treated surface) of the above-described base material layer / adhesive resin layer B / metal layer was prepared. ), While extruding the constituent resin of the adhesive resin layer A, it is laminated by a sand lamination method in which the sealant layer film is bonded, and consists of a base material layer / adhesive resin layer B / metal layer / adhesive resin layer A / sealant layer. A laminate was formed.

  In Examples 1 to 9 and Comparative Examples 1 and 2, after the obtained laminate was once cooled, the aluminum (metal layer) was heated to 190 ° C., and the temperature was maintained for 5 seconds to perform heat treatment. Thus, a battery packaging material was obtained.

  Comparative Example 3 is a two-component urethane adhesive of a polyester-based main agent and an isocyanic-based curing agent to a metal layer (chemically treated surface) of a laminate composed of the base material layer / adhesive resin layer B / metal layer. An adhesive resin layer A ′ made of an agent is formed so as to have a thickness of 4 μm, and then a sealant layer is bonded and laminated by a dry lamination method to form a base material layer / adhesive resin layer B / metal layer / adhesive resin layer A ′. A laminate composed of a sealant layer was formed to obtain a battery packaging material.

The structures, compositions, and thicknesses of the adhesive resin layer A and the sealant layer used in each example and comparative example are as follows. The “cycloolefin copolymer” shown below is a polymer obtained by copolymerizing ethylene and norbornene using a metallocene catalyst. In addition, “carboxylic acid modification” shown below is maleic anhydride modification.
[Example 1]
Adhesive resin layer A
Constituent resin: Carboxylic acid modified block polypropylene (MFR20.0)
Thickness: 20μm
Sealant layer layer structure: single layer Component resin: cycloolefin copolymer (glass transition temperature 65 ° C., MFR 0.9, weight molecular weight / number average molecular weight ratio 2.0)
Thickness: 10 μm

[Example 2]
Adhesive resin layer A
Component resin: Carboxylic acid-modified random polypropylene (MFR2.0)
Thickness: 20μm
Sealant layer layer structure: two layers comprising the following layers (1) and (2) Component resin of layer (1): cycloolefin copolymer (glass transition temperature 65 ° C., MFR2.
0, ratio of weight molecular weight / number average molecular weight 2.5)
Layer (1) thickness: 3 μm
Resin of layer (2): random propylene Thickness of layer (2): 25 μm
The layers (1) were laminated so that the adhesive resin layer A was in contact with each other, and the layer (2) formed the outermost surface.

[Example 3]
Adhesive resin layer A
Constituent resin: Carboxylic acid-modified random polypropylene (MFR8.0)
Thickness: 20μm
Sealant layer layer structure: 2 layers comprising the following layer (1) and layer (2) Component resin of layer (1): 50 parts by weight of block polypropylene and cycloolefin copolymer (glass transition temperature 140 ° C., MFR 0.08, weight molecular weight / Number average molecular weight ratio 1.9) Blend resin layer (1) thickness of 50 parts by weight: 10 μm
Resin of layer (2): Random propylene Layer (2) thickness: 15 μm
The layers (1) were laminated so that the adhesive resin layer A was in contact with each other, and the layer (2) formed the outermost surface.

[Example 4]
Adhesive resin layer A
Constituent resin: Carboxylic acid-modified random polypropylene (MFR8.0)
Thickness: 20μm
Sealant layer layer structure: two layers comprising the following layers (1) and (2) Component resin of layer (1): cycloolefin copolymer (glass transition temperature 65 ° C., MFR2.
0, ratio of weight molecular weight / number average molecular weight 2.5)
Layer (1) thickness: 500 μm
Resin of layer (2): Random propylene Layer (2) thickness: 100 μm
The layers (1) were laminated so that the adhesive resin layer A was in contact with each other, and the layer (2) formed the outermost surface.

[Example 5]
Adhesive resin layer A
Constituent resin: Carboxylic acid modified linear low density polyethylene (MFR42.0)
Thickness: 20μm
Sealant layer layer structure: single layer Component resin: cycloolefin copolymer (glass transition temperature 65 ° C., MFR 0.9, weight molecular weight / number average molecular weight ratio 2.0)
Thickness: 10 μm

[Example 6]
Adhesive resin layer A
Constituent resin: Carboxylic acid-modified random polypropylene (MFR8.0)
Thickness: 20μm
Sealant layer layer structure: single layer Component resin: 90 parts by weight of a copolymer of amorphous propylene and ethylene, and cycloolefin copolymer (glass transition temperature 75 ° C., MFR 2.0, weight molecular weight / number average molecular weight ratio 2.
5) Blend resin consisting of 10 parts by weight Thickness: 20 μm

[Example 7]
Adhesive resin layer A
Constituent resin: Carboxylic acid-modified random polypropylene (MFR12.0)
Thickness: 20μm
Sealant layer layer structure: two layers consisting of the following layer (1) and layer (2) Component resin of layer (1): Random polypropylene Layer (1) thickness: 10 μm
Component resin of layer (2): Blend resin layer comprising 3 parts by weight of block polypropylene and 10 parts by weight of cycloolefin copolymer (glass transition temperature 140 ° C., MFR 0.08, weight molecular weight / number average molecular weight ratio 1.9) 2) Thickness: 5μm
The layers (1) were laminated so that the adhesive resin layer A was in contact with each other, and the layer (2) formed the outermost surface.

[Example 8]
Adhesive resin layer A
Constituent resin: Carboxylic acid-modified random polypropylene (MFR8.0)
Thickness: 20μm
Sealant layer structure: 3 layers in which the following layer (1), layer (2) and layer (3) are laminated in order Layer (1) Component resin: Random polypropylene Layer (1) thickness: 10 μm
Component resin of layer (2): cycloolefin copolymer (glass transition temperature 175 ° C., MFR0
. 01, ratio of weight molecular weight / number average molecular weight 1.5)
Layer (2) thickness: 2 μm
Resin of layer (3): Random polypropylene Layer (3) thickness: 18μm
The layers (1) were laminated so that the adhesive resin layer A was in contact with each other, and the layer (3) formed the outermost surface.

[Example 9]
Adhesive resin layer A
Constituent resin: Carboxylic acid-modified random polypropylene (MFR 20.0)
Thickness: 20μm
Sealant layer structure: 3 layers in which the following layer (1), layer (2) and layer (3) are laminated in order Layer (1) Component resin: Random polypropylene Layer (1) thickness: 10 μm
Component resin of layer (2): 1 part of random polypropylene and cycloolefin copolymer (
Glass transition temperature 140 ° C., MFR 0.08, weight molecular weight / number average molecular weight ratio 1.9) 10
Thickness of blend resin layer (2) consisting of parts by weight: 10 μm
Resin of layer (3): random polypropylene Layer (3) thickness: 10 μm
The layers (1) were laminated so that the adhesive resin layer A was in contact with each other, and the layer (3) formed the outermost surface.

[Comparative Example 1]
Adhesive resin layer A
Component resin: Carboxylic acid-modified block polypropylene (MFR8.0)
Thickness: 20μm
Sealant layer structure: Single layer Constituent resin: Random polypropylene Thickness: 30 μm

[Comparative Example 2]
Adhesive resin layer A
Constituent resin: Random polypropylene Thickness: 20μm
Sealant layer structure: 3 layers in which the following layer (1), layer (2) and layer (3) are laminated in order Layer (1) Component resin: Random polypropylene Layer (1) thickness: 10 μm
Component resin of layer (2): cycloolefin copolymer (glass transition temperature 75 ° C., MFR2.
0, ratio of weight molecular weight / number average molecular weight 2.5)
Layer (2) thickness: 2 μm
Resin of layer (3): Random polypropylene Layer (3) thickness: 18μm
The layers (1) were laminated so that the adhesive resin layer A was in contact with each other, and the layer (3) formed the outermost surface.

[Comparative Example 3]
Adhesive resin layer A '
Constituent resin: 2-component urethane adhesive with polyester base and isocyanic curing agent Thickness: 4μm
Sealant layer layer structure: single layer Constituent resin: cycloolefin copolymer (glass transition temperature 75 ° C., MFR 2.0, weight molecular weight / number average molecular weight ratio 2.5)
Thickness: 30μm

<Measurement of ratio of weight molecular weight / number average molecular weight and glass transition temperature of cycloolefin copolymer>
The ratio of the weight molecular weight / number average molecular weight and the glass transition temperature of the cycloolefin copolymer used in the examples and comparative examples were determined under the following measurement conditions.
Measurement by the GPC method was performed under the following conditions to determine the ratio of weight molecular weight / number average molecular weight.
Measuring device: GPC 150-CALC (manufactured by Waters)
Column: AT-806M / S (manufactured by SHODEX) 2
Measurement temperature : 140 ° C
Sample preparation : About 4 ml of 1,2-dichlorobenzene was added to about 4 mg of the sample, heated with a heater and dissolved at 140 ° C. over 1 hour, and the insoluble matter was removed with a filter.

<Measurement conditions for glass transition temperature>
The glass transition temperature (Tg) was measured according to ISO11357.

Test example: performance evaluation About each battery packaging material obtained above, durability, short circuit property, the presence or absence of a crack, and heat resistance were evaluated. A specific evaluation method is as follows.
[Evaluation of electrolyte durability]
By performing plastic working using a mold, each battery packaging material was molded into a concave mold having a depth of 6 mm and a length and width of 50 mm × 35 mm. 3 g of the mixture having the composition shown below was sealed under a heat seal condition of 190 ° C., 2.0 MPa, 3.0 seconds with a seal width of 3 mm, and stored at 85 ° C. for 720 hours. After storage, the presence or absence of delamination of the metal layer and sealant layer in each battery packaging material was confirmed.
Composition of liquid mixture: A liquid mixture of ethylene carbonate, diethyl carbonate and dimethyl carbonate (1: 1: 1 by volume) containing 1M LiPF ₆ .

[Evaluation of water vapor barrier properties]
Each battery packaging material is used to make a packaging bag of 60 mm in length and 50 mm in length, filled with 3 g of a mixed solution containing ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1: 1: 1, and sealed. Sealing conditions were 190 ° C., 2.0 M, 3.0 seconds, and sealed in three directions so that the width was 3 mm. This was stored in a constant temperature and humidity chamber at 60 ° C. and 90% RH for 10 days, and the amount of water increase in the mixed solution was measured by the Karl Fischer method.

[Short-circuit evaluation]
By performing plastic working using a mold, a concave molded product having a depth of 6 mm and a length and width of 50 mm × 35 mm was prepared from each battery packaging material. Next, a lead wire film (thickness 50 μm) made of a predetermined material is wound around a predetermined position of a lead wire (nickel, 100 μm thickness, 4 mm width, length 25 mm) of the battery body, and then the battery body is After being inserted into a molded product and sandwiched so as to become a molded battery packaging material / lead wire / packaging material, the portion was heat-sealed at 190 ° C. and 2.0 MPa. Evaluation of short circuit property measured the time until the short circuit with a lead wire and the metal layer of the packaging material for batteries produced. The presence or absence of a short circuit is confirmed by a tester (judgment conditions: applied voltage 100 V, judgment resistance value 2000 MΩ), and by a cross-sectional photograph (optical microscope, magnification 200 times), the presence of contact between the lead wire, the battery packaging material, and the metal layer confirmed. In Examples 1 to 4, 6 to 9, and Comparative Examples 1 to 3, the lead wire film is made of carboxylic acid-modified polypropylene. In Example 5, the film is modified with carboxylic acid. The one made of linear low density polyethylene was used.

[Evaluation of cracks in molding]
By performing plastic working using a mold, each battery packaging material was formed into a concave mold having a depth of 6 mm and a size of 50 mm × 35 mm. About each battery packaging material, the extended side and bottom were observed with an optical microscope 500 times, and the presence or absence of cracks was visually confirmed.

[Check for cracks in folding after sealing]
By performing plastic working using a mold, each battery packaging material was formed into a concave mold having a depth of 6 mm and a size of 50 mm × 35 mm. In each battery packaging material subjected to plastic working, a portion not stretched (around the recess) and each battery packaging material not subjected to plastic working are 190 ° C., 2.0 MPa, 3.0 with a seal width of 3 mm. Heat sealing was performed under a heat sealing condition of seconds. After cooling this, folding was performed at a right angle with respect to the heat seal portion, the portion where the folding was performed was observed with an optical microscope 500 times, and the presence or absence of cracks was visually confirmed.

[Evaluation of heat resistance]
By performing plastic working using a mold, each battery packaging material was formed into a concave mold having a depth of 3 mm and a size of 50 mm × 35 mm. In each battery packaging material subjected to plastic working, a portion not stretched (around the recess) and each battery packaging material not subjected to plastic working are 190 ° C., 2.0 MPa, 3.0 with a seal width of 3 mm. Heat sealing was performed under a heat sealing condition of seconds. In a state where the pressure was reduced by 1 atm, the temperature was raised from room temperature at a heating rate of 10 ° C./min, and the temperature at the time of rupture (the heat seal part was separated) was measured.

[Evaluation results]
The obtained results are shown in Table 1. All of the battery packaging materials of Examples 1 to 9 did not cause delamination due to the electrolytic solution, had a water increase amount of 100 ppm or less, and had sufficient basic performance required as a battery packaging material. Moreover, in the battery packaging materials of Examples 1 to 9, the short-circuit time between the lead and the metal layer was as long as 10 seconds or more, and there were no cracks during molding and no cracks after sealing. Furthermore, the battery packaging materials of Examples 1 to 9 had a high bursting temperature of 110 ° C. or higher. On the other hand, the battery packaging material of Comparative Example 1 had a short short-circuit time, and cracks occurred at the time of molding and after the sealing. In addition, the battery packaging material of Comparative Example 2 was delaminated, had a high amount of moisture increase, cracked during molding and after sealing, and had a low heat-resistant burst temperature. Further, in the battery packaging material of Comparative Example 3, the short circuit time was as long as 10 seconds, but delamination occurred, the amount of water increase was high, and the heat-resistant burst temperature was low.

  From the above results, in the battery packaging material in which the base material layer, the metal layer, the adhesive resin layer, and the sealant layer are sequentially laminated, the adhesive resin layer includes a carboxylic acid-modified polyolefin, and the sealant layer includes ethylene and norbornene. It was confirmed that by including a cycloolefin copolymer made of the above copolymer, a short circuit between the electrode and the metal layer of the packaging material can be prevented, and cracks can be suppressed. In addition, the battery packaging material having the above-described configuration does not cause delamination due to the electrolyte, has an excellent water vapor barrier property, has a high heat-resistant burst temperature due to thermal expansion after sealing, and has basic performance required as a battery packaging material. It was confirmed that it was fully prepared.

1 Base material layer 2 Metal layer 3 Adhesive resin layer A
4 Sealant layer

Claims (8)

At least, it base layer, a metal layer, the adhesive resin layer, and a laminate sealant layer of the multilayer structure are sequentially laminated,
The thickness of the base material layer is 10 to 50 μm,
Wherein wherein the adhesive resin layer is a carboxylic acid-modified polyolefin, and viewed including the cycloolefin copolymer of at least one layer is made of a copolymer of ethylene and norbornene of the sealant layer,
The battery sealant is characterized in that the sealant layer is formed of a random copolymer of polypropylene to form an outermost surface .   The battery packaging material according to claim 1, wherein the cycloolefin copolymer has a glass transition temperature of 65C to 190C. The thickness of the sealant layer is 10 m to 500 m, the packaging material for battery according to claim 1 or 2. The battery packaging material according to claim 1 , wherein the carboxylic acid-modified polyolefin forming the adhesive resin layer is carboxylic acid-modified polyethylene or carboxylic acid-modified polypropylene. The battery packaging material according to any one of claims 1 to 4 , wherein the metal layer is aluminum. The chemical conversion treatment on at least one surface of the metal layer is applied, the battery packaging material according to any of claims 1-5. The battery packaging material according to any one of claims 1 to 6 , which is a packaging material for a secondary battery. At least a positive electrode, a negative electrode, and a battery device having an electrolyte have accommodated in the battery packaging the material according to any one of claims 1 to 7 batteries.