JP6326788B2 - 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, has excellent moldability, and has excellent electrolytic solution resistance.

  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 made thin and light. 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 packaging material having high properties 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 formability by focusing on the physical properties of the metal layer.

  In general, it is known that a metal material having a low proof stress and a high tensile strength is easily deformed and does not easily wrinkle when deep drawn, and has excellent workability (Non-Patent Documents). 1), conventionally, a metal material having a low yield strength is generally adopted as a metal layer even in a battery packaging material made of a film-like laminate.

  Furthermore, the battery packaging material is required to have high electrolytic solution resistance. For example, by using a polyester film as the base material layer of the battery packaging material, the electrolytic solution resistance can be further improved. However, the polyester film has a problem that the moldability is lower than that of the polyamide film and the like, and when the polyester film is used for the base material layer, pinholes are likely to occur during molding. Therefore, when using a polyester film for a base material layer in order to improve electrolyte solution resistance, it is especially difficult to improve the moldability of the battery packaging material.

JP 2008-287971 A

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

  The present invention provides 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. The main object is to provide a technology having excellent moldability, which is less likely to cause cracks and pinholes during molding of a base material layer containing a polyester film, while further improving the properties.

The inventor has conducted intensive studies to solve the above-mentioned problems. However, in the prior art, the aluminum foil used for the metal layer is considered to have better workability as the proof stress is lower. In the battery packaging material using an aluminum foil with a high yield strength of 0.2 to 140 N / mm ² when the tensile test in the direction parallel to the rolling direction is performed, surprisingly, In addition, even when the base material layer includes a polyester film, the battery packaging material can be provided with remarkably excellent moldability, and the occurrence rate of pinholes and cracks during molding can be greatly reduced. I found it. Furthermore, since the base material layer on which the aluminum foil is laminated contains a polyester film, the electrolytic solution resistance is also excellent. 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 base material layer includes a polyester film,
A packaging material for a battery, wherein the metal layer is an aluminum foil having a 0.2% yield strength of 55 to 140 N / mm ² when a tensile test in a direction parallel to the rolling direction is performed.
Item 2. Item 2. The battery packaging material according to Item 1, wherein the base material layer includes a laminate of a polyester film and a polyamide film.
Item 3. Item 3. The battery packaging material according to Item 2, wherein the laminate is a laminate of a biaxially stretched polyester film and a biaxially stretched polyamide film.
Item 4. Item 3. The battery packaging material according to Item 2, wherein the laminate is a coextruded laminate of a polyester resin and a polyamide resin.
Item 5. Item 5. The battery packaging material according to any one of Items 1 to 4, wherein the aluminum foil has a 0.2% yield strength of 65 to 90 N / mm ² when a tensile test in a direction parallel to the rolling direction is performed.
Item 6. Item 6. The battery packaging material according to any one of Items 1 to 5, wherein the aluminum foil has a thickness of 20 to 55 μm.
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 metal layer can follow appropriately in accordance with the shape of the mold at the time of molding, so that occurrence of pinholes, cracks and the like can be suppressed. Thus, since the battery packaging material of the present invention has excellent moldability, it can also contribute to the improvement of productivity. Furthermore, since the base material layer on which the metal layer is laminated contains a polyester film, the resistance to electrolyte solution is also excellent.

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.

The battery packaging material of the present invention comprises 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 a polyester film, and the metal layer is in the rolling direction. On the other hand, the aluminum foil has a 0.2% proof stress of 55 to 140 N / mm ² when a parallel tensile test is performed. 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. 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 that forms the outermost layer, and has insulating properties. In the present invention, the base material layer 1 includes a polyester film. Specific examples of the polyester resin constituting the polyester film include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. The polyester film is preferably a biaxially stretched polyester film and more preferably a biaxially stretched polyethylene terephthalate film from the viewpoint of imparting excellent moldability and electrolytic solution resistance to the battery packaging material. preferable. Biaxially stretched polyester films such as a biaxially stretched polyethylene terephthalate film are known and their production methods are also known. Specifically, the biaxially stretched polyester film has a stretching ratio of 2.0 to 2.0 in each of the flow direction (MD) and the vertical direction (TD) with respect to an unstretched raw film made of a raw material containing polyester, for example. After biaxial stretching under conditions of 6.0 times, it can be obtained by heat treatment at 210-230 ° C. As the biaxial stretching method, simultaneous biaxial stretching or sequential biaxial stretching by a tubular method or a tenter method can be adopted.

  From the viewpoint of further improving the moldability and the electrolytic solution resistance of the battery packaging material, the base material layer 1 more preferably includes a laminate of a polyester film and a polyamide film. In the laminate, the same polyester film as that described above is used. The polyamide resin constituting the polyamide film is preferably a nylon resin. Specific examples of the nylon resin include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD nylon), and the like. From the viewpoint of imparting excellent moldability and excellent electrolytic solution resistance to the battery packaging material, the polyamide film is preferably a biaxially stretched polyamide film, and is preferably a biaxially stretched nylon film. More preferred. Biaxially stretched polyamide films such as biaxially stretched nylon films are known and their production methods are also known. Specifically, the biaxially stretched polyamide film having such physical properties is, for example, stretched in the flow direction (MD) and the vertical direction (TD) with respect to an unstretched raw film made of a raw material containing polyamide. After biaxial stretching under conditions where the magnification is 3.0 to 3.5 times, it can be obtained by heat treatment at 150 to 200 ° C. As a biaxial stretching method, simultaneous biaxial stretching or sequential biaxial stretching by a tubular method or a tenter method can be adopted, and simultaneous biaxial stretching by a tubular method is preferable.

  From the viewpoint of further improving the moldability of the battery packaging material and the resistance to electrolytic solution, a particularly preferred form of the laminate of the polyester film and the polyamide film is a laminate of the biaxially stretched polyester film and the biaxially stretched polyamide film. And a co-extruded laminate of a polyester resin and a polyamide resin. For example, the biaxially stretched polyester film and the biaxially stretched nylon film can be laminated by a known method such as a dry lamination method or a sandwich lamination method via an adhesive. Moreover, also about the coextrusion laminated body of a polyester resin and a nylon resin, a polyester resin and a nylon resin can be laminated | stacked by coextrusion through an contact bonding layer. The type and amount of the adhesive layer used are the same as those of the adhesive layer 2 or the adhesive layer 5 described later.

  The base material layer 1 may be formed only from at least one of the above polyester film and the above laminated body, and may further have another resin film layer. Moreover, in the base material layer 1, each of the polyester film and the laminated body may be only one layer, or may be a plurality of layers. In addition, as other resin which comprises another resin film layer, an epoxy resin, an acrylic resin, a fluororesin, a polyurethane resin, a silicon resin, a phenol resin, these mixtures, a copolymer, etc. are mentioned. Moreover, as resin which comprises other resin film layers, the mixture, copolymer, etc. of these other resin and at least one of a polyester resin and a polyamide resin are mentioned.

  In the base material layer 1, the thickness of the polyester film is preferably about 5 to 20 μm, more preferably about 9 to 12 μm, from the viewpoint of further improving the moldability and the electrolytic solution resistance of the battery packaging material. Moreover, as a thickness of a polyamide film, from the same viewpoint, Preferably it is about 10-30 micrometers, More preferably, about 12-25 micrometers is mentioned. Furthermore, from the same viewpoint, when the base material layer 1 includes a laminate of a polyester film and a polyamide film, the ratio of the thickness of the polyester film to the polyamide film (polyester film / polyamide film) is 1/3 to 1 / 1 is preferable. The total thickness of the base material layer 1 is preferably about 10 to 50 μm, more preferably about 15 to 30 μm.

[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 the adhesive component that can be used to form the adhesive layer 2 include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and 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 resins, polyvinyl acetate resins, cellulose adhesives, (meth) acrylic resins, polyimide resins, urea resins, melamine resins and other amino resins, chloroprene rubber, nitrile rubber, steel - down rubber 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-based adhesive is preferable.

  About the thickness of the contact bonding layer 2, 1-10 micrometers, for example, Preferably 2-5 micrometers is mentioned.

[Metal layer 3]
In the battery packaging material of the present invention, the metal layer 3 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. In the battery packaging material of the present invention, the metal layer 3 is formed of an aluminum foil having a 0.2% proof stress of 55 to 140 N / mm ² when a tensile test in a direction parallel to the rolling direction is performed. By using the aluminum foil having a high yield strength as the metal layer 3 as described above, the battery packaging material of the present invention can be provided with excellent formability.

The aluminum foil used as the metal layer 3 may satisfy the 0.2% proof stress when the tensile test in the parallel direction (MD) with respect to the rolling direction is 55 to 140 N / mm ^2. From the viewpoint of providing excellent moldability, the 0.2% proof stress is preferably 65 to 90 N / mm ² .

Moreover, in the said aluminum foil, although it does not restrict | limit especially about 0.2% yield strength when a perpendicular test (TD) with respect to a rolling direction and a 45 degree direction tensile test are done, Preferably it is 55-140 N / mm < ² >. The degree, more preferably about 65 to 90 N / mm ² is mentioned.

In the aluminum foil, the tensile strength at break when a tensile test in the parallel direction (MD) to the rolling direction is performed is, for example, about 90 to 130 N / mm ² , preferably about 95 to 125 N / mm ² , and more preferably. Is about 100 to 110 N / mm ² . By providing such a tensile strength at break, it becomes possible to provide excellent moldability more effectively.

Further, the tensile strength at break when the aluminum foil is subjected to a tensile test in the direction perpendicular to the rolling direction (TD) and 45 ° is not particularly limited, but is preferably about 90 to 124 N / mm ² , for example. the 94~122N / mm ² approximately, more preferably include about 96~105N / mm ^2.

  The 0.2% proof stress, tensile breaking strength, and tensile breaking elongation are values measured by a tensile test specified in JIS Z 2241.

  The aluminum foil used as the metal layer 3 may be pure aluminum alone as long as it has the 0.2% proof stress described above, but an aluminum alloy is preferable. Examples of the aluminum alloy used for the aluminum foil include an aluminum-Fe alloy and an aluminum-Mn alloy, and preferably an aluminum-Fe alloy. Preferable examples of the aluminum foil used as the metal layer 3 include soft aluminum such as annealed aluminum (JIS A8021H-O) or (JIS A8079H-O).

  Aluminum foils having the above characteristics are known and their production methods are also known. Specifically, the aluminum foil having such characteristics is, for example, a step of homogenizing an aluminum metal or aluminum alloy at about 500 to 600 ° C. for about 1 to 2 hours, and heating at about 400 to 500 ° C. A step of cold rolling, a step of cold rolling, a step of intermediate annealing at about 300 to 450 ° C. for about 1 to 10 hours, a step of cold rolling, and a temperature of about 250 to 400 ° C. for about 30 to 100 hours. It can be manufactured through a step of final annealing under conditions.

  The thickness of the metal layer 3 (aluminum foil) is preferably about 20 to 55 μm, more preferably about 30 to 40 μm.

  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 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. In the general formulas (1) to (4), X is preferably any one of a hydrogen atom, a hydroxyl group, and a droxyalkyl 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.

  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. 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 3 in the chemical conversion treatment is not particularly limited. For example, the chromate treatment may be 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. Is about 1.0 to about 40 mg, and the aminated phenol polymer is 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.

[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.

  Moreover, as thickness of the sealant layer 4, although it can select suitably, 10-100 micrometers, Preferably 15-50 micrometers 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.

  About the thickness of the contact bonding layer 5, 2-50 micrometers, for example, Preferably 20-30 micrometers is mentioned.

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 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. Further, when the base material layer 1 is a coextruded laminate of a polyester resin and a polyamide resin, an adhesive is applied on the metal layer 3 and then the polyester resin and the polyamide resin are coated on the adhesive. The laminated body A can be formed by extruding. The laminate A may be formed of a film obtained by coextruding a polyester resin and a polyamide resin in advance. When the polyester resin and the polyamide resin are coextruded, an adhesive resin may be disposed between the polyester resin and the polyamide resin in order to further strengthen the adhesion between the polyester resin and the polyamide resin.

  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.

  As described above, a laminate composed of base material layer 1 / adhesive layer 2 / metal layer 3 whose surface is subjected to chemical conversion treatment as necessary / adhesive layer 5 / sealant layer 4 provided as necessary is formed. However, in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as necessary, it may be further subjected to a heat treatment such as a hot roll contact type, a hot air type, a near or far infrared type. 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.

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.

<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 the manufacturing conditions of the battery packaging material are as follows.

Examples 1-4 and Comparative Examples 1-2
In Examples 1 to 4 and Comparative Examples 1 and 2, a biaxially stretched polyethylene terephthalate film (thickness: 12 μm) was used as the resin film constituting the substrate layer 1. The biaxially stretched polyethylene terephthalate film has a stretching ratio of 2.0 to 6.0 times in the flow direction (MD) and the width direction (TD) with respect to an unstretched raw film made of a raw material containing polyethylene terephthalate. The film was manufactured by sequentially biaxially stretching by the tenter method under the following conditions, followed by heat treatment at 210 to 230 ° C.

  On the corona-treated surface of the biaxially stretched polyethylene terephthalate film, an adhesive layer 2 made of a two-component urethane adhesive of a polyester main agent and an isocyanic curing agent is formed to 3 μm, and an aluminum foil described later as a metal layer Was used, and a chemical conversion treatment surface of the metal layer was applied under pressure and heating to prepare a laminate in which biaxially stretched polyethylene terephthalate film / adhesive layer / aluminum foil was laminated in order.

  Separately, an acid-modified polypropylene resin (unsaturated carboxylic acid graft-modified random polypropylene (hereinafter referred to as PPa) graft-modified with an unsaturated carboxylic acid) constituting the adhesive layer 5 and a polypropylene (random copolymer (hereinafter referred to as PPa)) constituting the sealant layer 4 are used. Hereinafter, a two-layer coextruded film composed of an adhesive layer 5 having a thickness of 20 μm and a sealant layer 4 having a thickness of 20 μm was produced by coextrusion with PP)).

  Next, the metal layer (aluminum foil) of the laminate composed of the above biaxially stretched polyethylene terephthalate film / adhesive layer / aluminum foil is overlaid so that the adhesive layer 5 of the two-layer coextruded film prepared above is in contact, By performing thermal lamination by heating the metal layer 3 to 120 ° C., the base layer 1 (biaxially stretched polyethylene terephthalate film) / adhesive layer 2 / metal layer 3 / adhesive layer 5 / sealant layer 4 are in this order. A laminated body was obtained. After cooling the obtained laminated body once, it heated until it became 180 degreeC, the packaging material for batteries was obtained by hold | maintaining the temperature for 1 minute, and heat-processing.

Examples 5-8 and Comparative Examples 3-4
An adhesive layer comprising a two-component urethane adhesive of a polyester-based main agent and an isocyanic-based curing agent on the corona-treated surface of the biaxially stretched polyethylene terephthalate film (thickness: 12 μm) used in Examples 1-4 and Comparative Examples 1-2. Was formed so as to have a thickness of 3 μm, and the adhesive layer was laminated with a biaxially stretched nylon film (thickness of 15 μm) under pressure and heat to obtain a laminate of a biaxially stretched polyethylene terephthalate film and a biaxially stretched nylon film. . Next, an adhesive layer composed of the same two-component urethane adhesive is formed on the biaxially stretched nylon film side of the laminate so as to have a thickness of 3 μm, and an aluminum foil described later is used as the metal layer. The chemical conversion treatment surface of the layer was bonded under pressure and heat to produce a laminate in which biaxially stretched polyethylene terephthalate film / adhesive layer / biaxially stretched nylon film / adhesive layer / aluminum foil was laminated in this order.

  In addition, the biaxially stretched nylon films used in Examples 5 to 8 and Comparative Examples 3 to 4 are in the flow direction (MD) and the width direction (TD) with respect to the unstretched raw film made of a raw material containing nylon. It is manufactured by heat treatment at 150 to 200 ° C. after simultaneous biaxial stretching by a tubular method under the condition that each stretching ratio is 3.0 to 3.5 times.

  Separately, PPa constituting the adhesive layer 5 and PP constituting the sealant layer 4 were coextruded to produce a two-layer coextruded film comprising the adhesive layer 5 having a thickness of 20 μm and the sealant layer 4 having a thickness of 20 μm. .

  Next, adhesion of the bilayer coextruded film prepared above to the metal layer (aluminum foil) of the laminate composed of the above biaxially stretched polyethylene terephthalate film / adhesive layer / biaxially stretched nylon film / adhesive layer / aluminum foil By superposing layers 5 so as to be in contact with each other and heating the metal layer to 120 ° C. to perform thermal lamination, base layer 1 (biaxially stretched polyethylene terephthalate film / adhesive layer / biaxially stretched nylon film) / A laminate in which adhesive layer 2 / metal layer 3 / adhesive layer 5 / sealant layer 4 were laminated in order was obtained. After cooling the obtained laminated body once, it heated until it became 180 degreeC, the packaging material for batteries was obtained by hold | maintaining the temperature for 1 minute, and heat-processing.

Comparative Example 5
Substrate layer 1 (biaxially stretched nylon film) / adhesive layer 2 / metal layer 3 / in the same manner as Comparative Example 1 except that a biaxially stretched nylon film was used instead of the biaxially stretched polyethylene terephthalate film. A laminate in which the adhesive layer 5 / sealant layer 4 was laminated in order was obtained. After cooling the obtained laminated body once, it heated until it became 180 degreeC, the packaging material for batteries was obtained by hold | maintaining the temperature for 1 minute, and heat-processing.

  In Examples 1-8 and Comparative Examples 1-5, as aluminum foil which comprises the metal layer 3, AL foil 1-6 (thickness 40 micrometers) which consists of a soft aluminum ((JIS H4160 A8021H-O) of the physical property shown in Table 1 In the chemical conversion treatment of AL foils 1 to 6, a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid was applied to both surfaces of the metal layer by a roll coating method, This was carried out by baking for 20 seconds under conditions where the film temperature was 180 ° C. or higher.

  In Table 1, the AL foils 1 to 6 are a step of homogenizing the aluminum alloy at about 500 to 600 ° C for about 1 to 2 hours, a step of hot rolling at about 400 to 500 ° C, A step of intermediate rolling, a step of intermediate annealing at about 300 to 450 ° C. for about 1 to 10 hours, a step of cold rolling, and a step of final annealing at about 250 to 400 ° C. for about 30 to 100 hours. It is manufactured after passing through.

  In Examples 1 to 8 and Comparative Examples 1 to 5, 0.2% proof stress, tensile breaking strength, and tensile breaking elongation of the AL foils 1 to 6 were measured by a tensile test specified in JIS Z 2241. Table 2 shows combinations of the base material layer and the metal layer in Examples 1 to 8 and Comparative Examples 1 to 5.

<Evaluation of formability>
The battery packaging materials obtained in Examples 1 to 8 and Comparative Examples 1 to 5 were cut to produce 120 mm × 80 mm strips, which were used as test samples. Using a 30 × 50 mm molding die, cold molding was performed so that the molding depth was 5 mm or 6 mm. In addition, the test of depth 5mm was implemented in Examples 1-4 and Comparative Examples 1, 2, and 5, and the test of depth 6mm was implemented in Examples 5-8 and Comparative Examples 3-5. The presence or absence of occurrence of pinholes and cracks in the metal layer in the molded battery packaging material was confirmed, and the occurrence rate (%) was calculated. As for the occurrence rate of pinholes and cracks, those in which occurrence was observed even at one place were judged as defective, and 30 samples were used. The results are shown in Tables 3 and 4.

<Evaluation of electrolyte resistance>
On the surface of the base material layer of the battery packaging material obtained in Examples 1 to 8 and Comparative Examples 1 to 5, electrolyte solution (composition of electrolyte solution: ethylene carbonate, diethyl carbonate, dimethyl carbonate (volume) containing 1M LiPF ₆ A 1: 1: 1) mixed solution) was added dropwise, and the surface state after wiping off the electrolytic solution was observed after 5 minutes, 30 minutes and 1 hour, respectively. The evaluation criteria are as follows.
◎… No whitening after 1 hour ○… No whitening after 30 minutes △… No whitening after 5 minutes ×… Whitening after 5 minutes

As is apparent from Table 3, when molded at a molding depth of 5 mm, a biaxially stretched polyethylene terephthalate film was used as the substrate layer, and the 0.2% proof stress parallel to the rolling direction was 55 to 140 N / In the battery packaging material using an aluminum foil having a high yield strength of mm ^{2 as} a metal layer, the occurrence of pinholes and cracks can be remarkably suppressed, and the electrolyte resistance is also excellent (Example 1 to Example 1). 4). On the other hand, less than 55N / mm ² 0.2% proof stress in the parallel direction to the rolling direction, and 140 N / mm ² than in Comparative Examples 1 and 2 using the aluminum foil, biaxially stretched polyethylene terephthalate as a base material layer Since the film was used, the electrolytic solution resistance was excellent. However, when molding was performed at a molding depth of 5 mm, the incidence of pinholes and cracks was high, and the moldability was inferior to that of Example 1-4. . Moreover, in Comparative Example 5 in which only the biaxially stretched nylon film was used as the base material layer, the electrolytic solution resistance was inferior.

Further, as apparent from Table 4, when molded under a more severe condition of a molding depth of 6 mm, a laminate of a biaxially stretched polyethylene terephthalate film and a biaxially stretched nylon film is used as the base material layer, and the rolling direction In the battery packaging material using an aluminum foil having a high yield strength of 0.2 to 140 N / mm ^{2 in} the parallel direction as a metal layer, the occurrence of pinholes and cracks can be remarkably suppressed, And it was excellent also in the electrolyte solution resistance (Examples 5-8). On the other hand, less than 55N / mm ² 0.2% proof stress in the parallel direction to the rolling direction, and 140 N / in mm ² than Comparative Examples 3 and 4 An aluminum foil was used in the biaxially stretched polyethylene terephthalate as a base material layer Since the film was used, the electrolytic solution resistance was excellent, but when it was molded at a molding depth of 6 mm, the incidence of pinholes and cracks was high, and it was inferior in terms of moldability compared to Examples 5-8. . Moreover, in Comparative Example 5 in which only the biaxially stretched nylon film was used as the base material layer, the electrolytic solution resistance was inferior.

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

Claims (14)

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 a laminate of a polyester resin and a polyamide resin,
The battery packaging material, wherein the metal layer is an aluminum foil having a 0.2% yield strength of 65 to 90 N / mm ² when a tensile test in a direction parallel to the rolling direction is performed. The polyester resin is a biaxially stretched polyester film;
The polyamide resin is a biaxially stretched polyamide film;
The battery packaging material according to claim 1.   The battery packaging material according to claim 1, wherein the laminate is a co-extrusion laminate of the polyester resin and the polyamide resin. The battery packaging material according to any one of claims 1 to 3, wherein a ratio of the polyester resin to a thickness of the polyamide resin is 1/3 to 1/1. 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 base material layer includes a biaxially stretched polyester film,
The battery packaging material, wherein the metal layer is an aluminum foil having a 0.2% yield strength of 65 to 90 N / mm ² when a tensile test in a direction parallel to the rolling direction is performed. 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 a laminate of a polyester resin and a polyamide resin,
The metal layer is an aluminum foil having a 0.2% proof stress of 55 to 140 N / mm ² when a tensile test in a direction parallel to the rolling direction is performed,
A battery packaging material having a tensile breaking elongation in a direction parallel to a rolling direction of the aluminum foil of 12% or less. 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 a biaxially stretched polyester film,
The metal layer is an aluminum foil having a 0.2% proof stress of 55 to 140 N / mm ² when a tensile test in a direction parallel to the rolling direction is performed,
A battery packaging material having a tensile breaking elongation in a direction parallel to a rolling direction of the aluminum foil of 12% or less. The tensile breaking strength in the direction parallel to the rolling direction of the aluminum foil is 90 to 110 N / mm. ² The battery packaging material according to claim 1, wherein When the metal layer is subjected to a tensile test in a direction parallel to the rolling direction, the 0.2% yield strength is 65 to 140 N / mm. ² Is an aluminum foil,
The tensile breaking strength in the direction perpendicular to the rolling direction of the aluminum foil is 90 to 105 N / mm. ² The battery packaging material according to claim 1, wherein 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 a polyester film,
  When the metal layer is subjected to a tensile test in a direction parallel to the rolling direction, the 0.2% yield strength is 55 to 140 N / mm. ² Is an aluminum foil,
  The tensile breaking strength in the direction parallel to the rolling direction of the aluminum foil is 90 to 110 N / mm. ² A battery packaging material. 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 a polyester film,
  When the metal layer is subjected to a tensile test in a direction parallel to the rolling direction, the 0.2% yield strength is 65 to 140 N / mm. ² Is an aluminum foil,
  The tensile breaking strength in the direction perpendicular to the rolling direction of the aluminum foil is 90 to 105 N / mm. ² A battery packaging material. The battery packaging material according to any one of claims 1 to 11 , wherein the aluminum foil has a thickness of 20 to 55 µm. The battery packaging material according to any one of claims 1 to 12 , which is a packaging material for a secondary battery. At least a positive electrode, a negative electrode, and a battery element having an electrolyte, are accommodated with the battery packaging material according to any one of claims 1 to 13 cells.