HK1234897B - Cell packaging material - Google Patents

Description

Battery packaging materials

Technical Field

The present invention relates to a battery packaging material having high moldability and excellent continuous battery productivity.

Background Art

A wide variety of batteries have been developed, and packaging materials are essential components for encapsulating battery components such as electrodes and electrolytes. Previously, metal packaging materials were the most commonly used for battery packaging. In recent years, with the increasing performance of electric vehicles, hybrid vehicles, personal computers, cameras, and mobile phones, batteries are being required to have a wider range of shapes, as well as thinner and lighter weight. However, the metal battery packaging materials that have been widely used in the past have drawbacks such as difficulty adapting to the increasing variety of shapes and limitations in achieving lightweight performance.

To this end, a film-like laminate comprising a base layer, an adhesive resin layer, a metal layer, and a sealant layer laminated in this order has been proposed as a battery packaging material that can be easily processed into a variety of shapes and can achieve thinning and lightweighting (see, for example, Patent Document 1). This film-like battery packaging material is formed so that the battery element can be encapsulated by placing the sealant layers opposite each other and heat-sealing the peripheral edges together.

When enclosing battery elements in battery packaging materials, they are molded using a mold to create a space to house the battery elements. During this molding process, the battery packaging material is stretched, which can easily cause cracks and pinholes in the metal layer of the mold's flange. This problem is particularly prominent with the recent demand for smaller and thinner batteries, which has led to the demand for thinner battery packaging materials.

To address this issue, unsaturated fatty acid amide is typically added to the sealing layer, allowing it to ooze thinly onto the sealing surface, enhancing slipperiness. Another known method involves applying a lubricant coating to the surface of the base material layer, the outermost layer of the battery packaging material, to improve the base material's slipperiness. Similarly, applying a lubricant coating to the surface of the innermost sealing layer of the battery packaging material is also conceivable. These methods facilitate the insertion of the battery packaging material into the mold during molding, thus preventing cracks and pinholes in the battery packaging material.

However, unsaturated fatty acid amides are relatively easy to move inside a sealant layer such as polypropylene, and the ease of movement within the sealant layer is particularly affected by the storage environment. For example, when battery packaging materials are stored at high temperatures exceeding 40°C, unsaturated fatty acid amides may enter the sealant layer. As a result, there is a concern that the slipperiness of the sealant layer surface may decrease, leading to reduced moldability. On the other hand, when battery packaging materials are stored at low temperatures below room temperature, the saturated solubility of unsaturated fatty acid amides within the sealant layer decreases. As a result, there is a concern that unsaturated fatty acid amides may ooze out of the sealant layer surface in large quantities, adhering to processing equipment such as molding dies as white powder, significantly reducing productivity.

Because of these issues, it is difficult to prevent the aforementioned problems of reduced moldability and white powder by adding a constant amount throughout the year. Furthermore, while forming separate coating layers on the outermost and innermost layers of battery packaging materials reduces the risk of these problems, there is the disadvantage of increased manufacturing costs.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2008-287971

Summary of the Invention

Problems to be solved by the invention

Under such circumstances, an object of the present invention is to provide a battery packaging material having high moldability and excellent continuous battery productivity.

Methods for solving problems

The inventors of the present invention conducted intensive research to address the aforementioned issues. As a result, they discovered that a battery packaging material comprising a laminate comprising at least a substrate layer, a metal layer, and a sealant layer laminated in this order, wherein the sealant layer contains multiple amide-based lubricants, and at least one of the fatty acid amide-based lubricants is a saturated fatty acid amide, can maintain lubricity even after high-temperature storage and prevent the formation of white powder caused by excessive lubricant seepage, thereby improving the continuous productivity of the battery. The present invention was completed through further research based on these findings.

That is, the present invention provides the following aspects of the invention.

Item 1. A battery packaging material comprising a laminate in which at least a base layer, a metal layer, and a sealant layer are laminated in this order, wherein:

In the sealing layer, there are various fatty acid amide lubricants.

At least one of the fatty acid amide-based lubricants is a saturated fatty acid amide.

Item 2. The battery packaging material according to Item 1, wherein the plurality of fatty acid amide-based lubricants further contain an unsaturated fatty acid amide.

Item 3. The battery packaging material according to Item 1 or 2, wherein the saturated fatty acid amide has 18 or more carbon atoms.

Item 4. The battery packaging material according to any one of Items 1 to 3, wherein the saturated fatty acid amide is behenic acid amide.

Item 5. The battery packaging material according to Item 2, wherein the unsaturated fatty acid amide is erucamide.

Item 6. The battery packaging material according to any one of Items 1 to 5, wherein the sealant layer is formed of polypropylene.

Item 7. The battery packaging material according to any one of Items 1 to 6, wherein an adhesive resin layer is laminated between the metal layer and the sealant layer.

Item 8. The battery packaging material according to any one of Items 1 to 7, wherein the adhesive resin layer is formed of acid-modified polypropylene.

Item 9. The battery packaging material according to Item 7 or 8, wherein the total thickness of the adhesive resin layer and the sealant layer is 20 to 100 μm.

Item 10. The battery packaging material according to any one of Items 7 to 9, wherein the total content of the saturated fatty acid amide in the adhesive resin layer and the sealant layer is 20 ppm or more.

Item 11. The battery packaging material according to any one of Items 1 to 10, wherein the metal layer is formed of aluminum foil.

Item 12. A battery comprising a battery element including at least a positive electrode, a negative electrode, and an electrolyte housed in the battery packaging material according to any one of Items 1 to 11.

Item 13. A method for manufacturing a battery, wherein:

The method comprises the steps of housing a battery element having at least a positive electrode, a negative electrode and an electrolyte in a battery packaging material.

The battery packaging material comprises a laminate comprising at least a base material layer, a metal layer, and a sealing layer laminated in this order.

In the sealing layer, there are various fatty acid amide lubricants.

At least one of the fatty acid amide-based lubricants is a saturated fatty acid amide.

Item 14. Use of a laminate as a battery packaging material, wherein:

The laminated body comprises at least a base material layer, a metal layer and a sealing layer laminated in sequence.

In the sealing layer, there are various fatty acid amide lubricants.

At least one of the fatty acid amide-based lubricants is a saturated fatty acid amide.

Effects of the Invention

According to the present invention, a battery packaging material having high moldability and excellent continuous battery productivity can be provided, and a battery using the battery packaging material can also be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a diagram showing an example of the cross-sectional structure of the battery packaging material of the present invention.

DETAILED DESCRIPTION

The battery packaging material of the present invention comprises a laminate comprising at least a base layer, a metal layer, and a sealant layer laminated in this order. The sealant layer contains multiple amide-based lubricants, at least one of which is a saturated fatty acid amide. The battery packaging material of the present invention is described in detail below.

1. Laminated structure of battery packaging materials

As shown in Figure 1, the battery packaging material of the present invention comprises a laminate comprising at least a base layer 1, a metal layer 3, and a sealant layer 4 laminated in this order. In the battery packaging material of the present invention, the base layer 1 forms the outermost layer, and the sealant layer 4 forms the innermost layer. Specifically, during battery assembly, the sealant layers 4 located around the periphery of the battery element are thermally welded together to seal the battery element, thereby encapsulating the battery element.

As shown in FIG1 , in the battery packaging material of the present invention, an adhesive resin layer 2 may be provided, if necessary, between the base material layer 1 and the metal layer 3 to improve their adhesion. Furthermore, as shown in FIG1 , in the battery packaging material of the present invention, an adhesive resin layer 5 may be provided, if necessary, between the metal layer 3 and the sealant layer 4 to improve their adhesion.

As mentioned above, in recent years, the demand for smaller and thinner batteries has led to a demand for thinner battery packaging materials. While the total thickness of the battery packaging material of the present invention is not particularly limited, it is preferably approximately 25 to 80 μm, and more preferably approximately 30 to 60 μm, from the perspective of achieving high moldability and excellent continuous battery production in response to the demand for further thinning.

2. Composition of each layer forming the battery packaging material

[Base material layer 1]

In the battery packaging material of the present invention, base layer 1 is the outermost layer. The raw material for forming base layer 1 is not particularly limited as long as it has insulating properties. Examples of raw materials for forming base layer 1 include polyesters, polyamides, epoxy resins, acrylic resins, fluororesins, polyurethanes, silicone resins, phenolic resins, polyetherimides, polyimides, and mixtures and copolymers thereof.

Specific examples of polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, copolyesters containing ethylene terephthalate as a main repeating unit, and copolyesters containing butylene terephthalate as a main repeating unit. In addition, as copolyesters mainly composed of ethylene terephthalate as repeating units, specifically, copolymer polyesters mainly composed of ethylene terephthalate as repeating units and polymerized with ethylene isophthalate (hereinafter referred to as "poly(terephthalic acid/isophthalic acid) glycol" for abbreviated purposes), poly(terephthalic acid/isophthalic acid) glycol, poly(terephthalic acid/adipate) glycol, poly(terephthalic acid/sodium sulfonated isophthalic acid) glycol, poly(terephthalic acid/sodium isophthalate) glycol, poly(terephthalic acid/phenyl-dicarboxylic acid) glycol, poly(terephthalic acid/decanedicarboxylic acid) glycol, etc. can be listed. Specific examples of copolyesters containing butylene terephthalate as a main repeating unit include copolymer polyesters containing butylene terephthalate as a main repeating unit and polymerized with butylene isophthalate (hereinafter referred to as "poly(butylene terephthalate/isophthalate)"), poly(butylene terephthalate/adipate), poly(butylene terephthalate/sebacate), poly(butylene terephthalate/decanedicarboxylate), and polybutylene naphthalate. These polyesters may be used alone or in combination of two or more. Polyesters have advantages such as excellent electrolyte resistance and resistance to whitening due to electrolyte adhesion, making them suitable for use as raw materials for forming the base layer 1.

Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 6,6; aromatic polyamides such as hexamethylenediamine-isophthalic acid-terephthalic acid copolymers such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (I represents isophthalic acid and T represents terephthalic acid) containing structural units derived from terephthalic acid and/or isophthalic acid; and polyamides containing hexamethylenediamine (MXD6); alicyclic polyamides such as polyaminomethylcyclohexylhexanediamine (PACM6); and polyamides obtained by copolymerizing a lactone component and an isocyanate component such as 4,4'-diphenylmethane diisocyanate; polyesteramide copolymers and polyetheresteramide copolymers which are copolymers of a copolymerized polyamide with a polyester or a polyalkylene ether glycol; and copolymers thereof. These polyamides may be used alone or in combination of two or more. Stretched polyamide films have excellent stretchability and can prevent whitening caused by resin cracking of the base layer 1 during molding, making them well suited for use as a raw material for forming the base layer 1.

The base layer 1 can be formed from a uniaxially or biaxially stretched resin film, or an unstretched resin film. Uniaxially or biaxially stretched resin films, particularly biaxially stretched resin films, are preferably used as the base layer 1 because they have improved heat resistance due to oriented crystallization. Alternatively, the base layer 1 can be formed by applying the aforementioned raw materials onto the metal layer 3.

Among these, as the resin film forming the base material layer 1 , preferably nylon and polyester are used, more preferably biaxially stretched nylon and biaxially stretched polyester are used, and particularly preferably biaxially stretched nylon is used.

The substrate layer 1 can also be laminated with at least one of a resin film and a coating layer of different raw materials in order to improve the pinhole resistance and the insulation when forming the battery packaging body. Specifically, a multilayer structure obtained by laminating a polyester film and a nylon film, a multilayer structure obtained by laminating a biaxially stretched polyester and a biaxially stretched nylon, etc. can be cited. When the substrate layer 1 is a multilayer structure, each resin film can be bonded via an adhesive, or can be directly laminated without an adhesive. When bonding without an adhesive, for example, a method of bonding in a hot melt state such as a co-extrusion method, a sandwich method, and a hot lamination method can be cited. In addition, when bonding via an adhesive, the adhesive used can be a two-liquid curing adhesive, or a one-liquid curing adhesive. In addition, there is no particular limitation on the bonding mechanism of the adhesive, and it can be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a hot pressing type, an electron beam curing type such as UV or EB, etc. Components of the adhesive include polyester resins, polyether resins, polyurethane resins, epoxy resins, phenolic resins, polyamide resins, polyolefin resins, polyvinyl acetate resins, cellulose resins, (meth)acrylic resins, polyimide resins, amino resins, rubber, and silicone resins.

To improve formability, the substrate layer 1 may be made low-friction. When making the substrate layer 1 low-friction, the coefficient of kinetic friction of its surface is not particularly limited; for example, it can be 0.3 or less. Examples of methods for making the substrate layer 1 low-friction include roughening, forming a lubricant coating layer, or a combination thereof. In the present invention, the coefficient of kinetic friction of the surface is a value measured according to JIS K7125.

Examples of roughening treatments include methods of pre-adding a roughening agent to the substrate layer 1 to create surface irregularities, transfer methods using an embossing roller with heat and pressure, dry or wet sandblasting, and mechanical surface roughening using a file. Examples of roughening agents include microparticles with a particle size of approximately 0.5 nm to 5 μm. The material of the roughening agent is not particularly limited, and examples include metals, metal oxides, inorganic substances, and organic substances. Furthermore, the shape of the roughening agent is also not particularly limited, and examples include spherical, fibrous, plate-like, amorphous, and hollow spherical shapes. As roughening agent, specifically, talc, silicon dioxide, graphite, kaolin, bentonite, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, potassium sulfate, barium sulfate, potassium carbonate, potassium silicate, lithium carbonate, potassium benzoate, potassium oxalate, magnesium stearate, aluminum oxide, carbon black, carbon nanotubes, high melting point nylon, cross-linked acrylic acid, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, nickel etc. can be enumerated.These roughening agents can be used alone or in combination of two or more.Among these roughening agents, from the viewpoint of dispersion stability, cost etc., preferably silicon dioxide, barium sulfate, titanium oxide are enumerated.In addition, to roughening agent, various surface treatments such as insulation treatment, high dispersibility treatment etc. can be imposed on the surface.

The lubricant coating layer can be formed by allowing the lubricant to precipitate on the surface of the substrate layer 1 by exudation, or by laminating the lubricant on the substrate layer 1. The lubricant is not particularly limited, and examples thereof include amide lubricants described below, metal soaps, hydrophilic silicones, silicone-grafted acrylics, silicone-grafted epoxies, silicone-grafted polyethers, silicone-grafted polyesters, block silicone-acrylic copolymers, polyglycerol-modified silicones, and paraffin waxes. These lubricants may be used alone or in combination of two or more.

The thickness of the base material layer 1 is, for example, 10 to 50 μm, preferably 15 to 30 μm.

[Adhesive resin layer 2]

In the battery packaging material of the present invention, the adhesive resin layer 2 is a layer provided as needed to bond the base material layer 1 and the metal layer 3 together.

The adhesive resin layer 2 is formed from an adhesive capable of bonding the base material layer 1 to the metal layer 3. The adhesive used to form the adhesive resin layer 2 may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the adhesive used to form the adhesive resin layer 2 is not particularly limited in its bonding mechanism and may be any of chemical reaction type, solvent evaporation type, hot melt type, and hot press type.

Specific examples of the resin component of the adhesive that can be used in forming the adhesive resin layer 2 include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolyester; polyether adhesives; polyurethane adhesives; epoxy resins; phenolic resins; polyamide resins such as nylon 6, nylon 66, nylon 12, and copolyamide; polyolefin resins such as polyolefin, acid-modified polyolefin, and metal-modified polyolefin; polyvinyl acetate resins; cellulose adhesives; (meth)acrylic resins; polyimide resins; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; silicone resins; fluorinated ethylene propylene copolymers, etc. These adhesive components can be used alone or in combination of two or more. There are no particular limitations on the combination of two or more adhesive components. Examples of adhesive components include mixed resins of polyamide and acid-modified polyolefin, mixed resins of polyamide and metal-modified polyolefin, mixed resins of polyamide and polyester, polyester and acid-modified polyolefin, and mixed resins of polyester and metal-modified polyolefin. Among these, polyurethane-based two-component curing adhesives are preferred, given their excellent ductility, durability under high humidity conditions, strain suppression, and suppression of thermal degradation during heat sealing, as well as their ability to effectively suppress delamination by reducing the lamination strength between the substrate layer 1 and the metal layer 3. Polyamide, polyester, or blended resins of these with modified polyolefins are also preferred.

Furthermore, the adhesive resin layer 2 may be multilayered with different adhesive components. When the adhesive resin layer 2 is multilayered with different adhesive components, from the perspective of improving the lamination strength between the base material layer 1 and the metal layer 3, it is preferable to select a resin having excellent adhesion to the base material layer 1 for the adhesive component disposed on the base material layer 1 side, and to select an adhesive component having excellent adhesion to the metal layer 3 for the adhesive component disposed on the metal layer 3 side. When the adhesive resin layer 2 is multilayered with different adhesive components, specifically, preferred examples of the adhesive component disposed on the metal layer 3 side include acid-modified polyolefins, metal-modified polyolefins, mixed resins of polyesters and acid-modified polyolefins, and resins containing copolyesters.

The thickness of the adhesive resin layer 2 is, for example, 2 to 50 μm, preferably 3 to 25 μm.

[Metal layer 3]

In the battery packaging material of the present invention, the metal layer 3 not only increases the strength of the packaging material but also serves as a barrier layer to prevent water vapor, oxygen, light, and the like from invading the interior of the battery. Specifically, metals forming the metal layer 3 include aluminum, stainless steel, titanium, and other metal foils. Among these, aluminum is preferably used. To prevent wrinkles and pinholes during the manufacture of the packaging material, in the present invention, soft aluminum, such as annealed aluminum (JIS A8021P-O) or (JIS A8079P-O), is preferably used as the metal layer 3.

The thickness of the metal layer 3 is, for example, 10 to 200 μm, preferably 20 to 100 μm.

In addition, the metal layer 3 is subjected to a chemical conversion treatment on at least one surface, preferably at least the surface on the sealing layer 4 side, and more preferably on both surfaces, in order to stabilize adhesion, prevent dissolution, corrosion, etc. Here, the chemical conversion treatment refers to a treatment for forming an acid-resistant film on the surface of the metal layer 3. Examples of chemical conversion treatment include chromate treatment using chromic acid compounds such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium hydrogen phosphate, chromate acetoacetate, chromium chloride, and potassium chromium sulfate; chromate phosphate treatment using phosphoric acid compounds such as sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid; and chromate treatment using an aminophenol polymer containing repeating units represented by the following general formulas (1) to (4). In addition, the aminophenol polymer may contain one repeating unit represented by the following general formulas (1) to (4) alone or in any combination of two or more.

In the general formulae (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. Furthermore, 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 formulae (1) to (4), examples of the alkyl group represented by X, R ¹ , and R ² include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. Furthermore, examples of the hydroxyalkyl group represented by X, R ¹ , and R ² include linear or branched alkyl groups having 1 to 4 carbon atoms substituted with one hydroxyl group, such as hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-hydroxybutyl, 2-hydroxybutyl, 3-hydroxybutyl, and 4-hydroxybutyl. In the general formulae (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 aminophenol polymer containing repeating units represented by general formulae (1) to (4) is, for example, about 500 to 1,000,000, preferably about 1,000 to 20,000.

Another method for imparting corrosion resistance to the metal layer 3 through chemical conversion treatment includes applying a coating solution containing fine particles of a metal oxide such as aluminum oxide, titanium oxide, cerium oxide, or tin oxide, or barium sulfate, dispersed in phosphoric acid, followed by calcining at 150°C or above to form a corrosion-resistant layer on the surface of the metal layer 3. Alternatively, a resin layer formed by crosslinking a cationic polymer with a crosslinking agent may be formed on the corrosion-resistant layer. Examples of cationic polymers include polyethyleneimine, ionic polymer complexes formed from polyethyleneimine and a polymer containing a carboxylic acid, primary amine-grafted acrylic resins containing a primary amine grafted onto an acrylic backbone, polyallylamine or its derivatives, and aminophenol. These cationic polymers may be used alone or in combination of two or more. Examples of crosslinking agents include compounds having at least one functional group selected from the group consisting of isocyanate, glycidyl, carboxyl, and oxazoline, and silane coupling agents. These crosslinking agents may be used alone or in combination of two or more.

These chemical conversion treatments may be performed individually or in combination of two or more. Furthermore, these chemical conversion treatments may be performed using one compound alone or in combination of two or more compounds. Among these, chromic acid and chromate treatments are preferred, and chromate treatments combining a chromic acid compound, a phosphoric acid compound, and an aminophenol polymer are more preferred.

There is no particular limitation on the amount of the acid-resistant film formed on the surface of the metal layer 3 during the chemical conversion treatment. For example, when a chromate treatment is performed by combining a chromic acid compound, a phosphoric acid compound, and an aminophenol polymer, it is desirable that the chromic acid compound be contained in an amount of about 0.5 to about 50 mg, preferably about 1.0 to about 40 mg, calculated as chromium per 1 ^m2 of the surface of the metal layer 3; the phosphorus compound be contained in an amount of about 0.5 to about 50 mg, preferably about 1.0 to about 40 mg, calculated as phosphorus per 1 m2; and the aminophenol polymer be contained in an amount of about 1 to about 200 mg, preferably about 5.0 to 150 mg.

The chemical conversion treatment is performed by applying a solution containing the compound used to form the acid-resistant film to the surface of the metal layer 3 by a bar coating method, a roller coating method, a gravure printing method, a dipping method, or the like, and then heating the metal layer 3 to a temperature of approximately 70 to 200°C. Furthermore, before the chemical conversion treatment is performed on the metal layer 3, the metal layer 3 may be subjected to a degreasing treatment by an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing such a degreasing treatment, the chemical conversion treatment of the surface of the metal layer 3 can be performed more efficiently.

[Sealing 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-fusion bonding the sealant layers to each other during battery assembly.

The sealant layer 4 is preferably formed of a polyolefin resin. The polyolefin resin is not particularly limited as long as it can be heat-sealed, and examples thereof include polyolefins, cyclic polyolefins, carboxylic acid-modified polyolefins, and carboxylic acid-modified cyclic polyolefins.

Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and terpolymers of ethylene-butene-propylene. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is more preferred.

The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin as a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of the cyclic monomer as a constituent monomer of the cyclic polyolefin include cyclic olefins such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic olefins are preferred, and norbornadiene is more preferred.

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

The carboxylic acid-modified cyclic polyolefins are polymers obtained by copolymerizing a portion of the monomers constituting the cyclic polyolefin with an α,β-unsaturated carboxylic acid or its anhydride, or by block or graft polymerization of an α,β-unsaturated carboxylic acid or its anhydride onto the cyclic polyolefin. The carboxylic acid-modified cyclic polyolefins are the same as those described above. The carboxylic acid used in the modification is the same as that used in the modification of the acid-modified cyclic olefin copolymers.

Among these resin components, preferably, polyolefins and carboxylic acid-modified polyolefins are used, and more preferably, polypropylene and carboxylic acid-modified polypropylene are used.

The sealant layer 4 may be formed from a single resin component alone, or from a polymer blend of two or more resin components. Furthermore, the sealant layer 4 may be formed from a single layer, or from two or more layers composed of the same or different resin components. Preferred layer structures when the sealant layer 4 is formed from two or more layers include, for example, a layer structure in which the outermost layer is formed from polypropylene, and the layer on the metal layer 3 side is formed from carboxylic acid-modified polypropylene.

The thickness of the sealing layer 4 can be appropriately set, and is, for example, approximately 10 to 100 μm, preferably approximately 15 to 50 μm.

In the battery packaging material of the present invention, the sealant layer 4 contains multiple amide-based lubricants. During battery production, when the battery packaging material of the present invention is molded, the amide-based lubricant is present on the surface of the sealant layer 4. This improves the slipperiness of the sealant layer 4 surface, thereby enhancing the moldability of the battery packaging material of the present invention. Furthermore, the amide-based lubricant readily migrates through the resins, such as the polyolefin resin, that form the sealant layer 4 and the adhesive resin layer 5. Therefore, even if the amide-based lubricant is present in only one of the sealant layer 4 and the adhesive resin layer 5 immediately after manufacture, the sealant layer 4 will also contain the amide-based lubricant over time.

Methods for providing the sealant 4 with an amide lubricant include applying the amide lubricant to the surface of the sealant 4 of the battery packaging material, or blending the amide lubricant into the polyolefin resin or the like forming the sealant 4 and/or the adhesive resin layer 5. Furthermore, even when blending the amide lubricant into the polyolefin resin or the like forming the sealant 4 and/or the adhesive resin layer 5, the amide lubricant can be present on the surface of the sealant 4 by causing the amide lubricant to seep out of the sealant 4. Furthermore, when applying the amide lubricant to the surface of the sealant 4 of the battery packaging material, a portion of the amide lubricant migrates from the surface to the interior, thereby allowing the amide lubricant to be present inside the sealant 4 and/or the adhesive resin layer 5. Furthermore, as a method for causing the amide lubricant to seep out onto the surface of the sealant layer 4, the battery packaging material is generally aged at a slightly elevated temperature of approximately 30 to 50°C for several hours to three days to promote the seepage. However, as the melting point of the amide lubricant approaches, the saturated amount of lubricant applied to the sealant layer 4 and the adhesive resin layer 5 increases, so care must be taken regarding the amount added and the aging temperature.

The present invention is characterized in that a plurality of fatty acid amide-based lubricants are present in the sealant layer 4 and at least one of the fatty acid amide-based lubricants is a saturated fatty acid amide.

As mentioned above, existing battery packaging materials also incorporate or apply amide lubricants to the sealant layer. However, it is known that even when the amount of amide lubricant applied or incorporated into the sealant layer is set to a specified amount, the amide lubricant sometimes adheres to the mold during molding of the battery packaging material, reducing continuous productivity and sometimes causing cracks and pinholes in the battery packaging material. Furthermore, this problem is known to occur both when the amide lubricant is incorporated into the sealant layer and when it is applied. In both cases, it is caused by significant changes in the environment, particularly temperature, during the period from the manufacture of the battery packaging material to the storage and transportation environment before molding. For example, it is believed that when the battery packaging material is exposed to high temperatures above 40°C, the saturation solubility of the amide lubricant in the sealant layer increases, causing the amide lubricant present on the surface of the sealant layer to migrate into the interior of the sealant layer, thereby reducing the moldability of the sealant layer. On the other hand, to prevent this, the amount of amide lubricant is significantly increased. However, when not exposed to high temperatures, the excessive amount of amide lubricant present on the surface of the sealant layer can cause the lubricant to adhere to the mold during molding, forming lumps and contaminating the mold. Consequently, even if the same amount of amide lubricant is used during the manufacture of battery packaging materials, the amount of amide lubricant present on the surface during molding can vary significantly depending on the storage environment, which can lead to adhesion of the amide lubricant to the mold and reduce continuous productivity, or even cause cracks and pinholes in the battery packaging materials. Furthermore, proper management of the environment, particularly temperature, during the manufacturing and molding of the battery packaging materials, from the time the battery packaging materials are manufactured until they are ready for molding, can suppress variations in the amount of amide lubricant during the manufacturing and molding of the battery packaging materials. However, in practice, there are cases where the storage and transportation environments are not properly managed, resulting in problems with moldability and continuous productivity not occurring until the molding process for battery manufacturing.

In contrast, the battery packaging material of the present invention exhibits high moldability and excellent continuous battery production even when exposed to high temperatures due to the presence of multiple fatty acid amide lubricants in the sealant layer 4, at least one of which is a saturated fatty acid amide. The mechanism by which the battery packaging material of the present invention achieves these excellent effects is unclear, but the following is a possible explanation. Specifically, in the battery packaging material of the present invention, the saturated fatty acid amide present on the surface of the sealant layer 4 by coating or exudation, once present on the surface of the sealant layer 4, is less likely to migrate into the interior of the sealant layer 4 due to its saturated aliphatic hydrocarbon group, even when exposed to high temperatures. Therefore, even when the battery packaging material is stored or transported at high temperatures of 40°C or above, where other amide lubricants migrate to the interior, the saturated fatty acid amide remains on the surface of the sealant layer 4. Furthermore, when not exposed to high temperatures, the presence of amide lubricants other than the saturated fatty acid amide within or on the surface of the sealant layer 4 allows for high moldability and excellent continuous battery production.

As saturated fatty acid amide, one may be used alone or in combination of two or more. As saturated fatty acid amide, there is no particular limitation. From the viewpoint of further improving moldability and continuous production of the battery, preferably saturated fatty acid amides with more than 18 carbon atoms are listed, more preferably stearic acid amide, behenic acid amide, arachidic acid amide, etc., and particularly preferably behenic acid amide is listed.

In the present invention, amide-based lubricants other than saturated fatty acid amides are not particularly limited. For example, amides other than the saturated fatty acid amides exemplified above, unsaturated fatty acid amides, substituted amides, hydroxymethylamides, saturated fatty acid bisamides, and unsaturated fatty acid bisamides can be mentioned. Specific examples of other saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitamide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide. Specific examples of hydroxymethylamides include hydroxymethylstearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearamide, ethylene biscapric amide, ethylene bislauric amide, ethylene bisstearamide, ethylene bishydroxystearamide, ethylene bisbehenic amide, hexamethylene bisstearamide, hexamethylene bisbehenic amide, hexamethylene hydroxystearamide, N,N'-distearyl adipamide, and N,N'-distearyl sebacamide. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleamide, ethylene biserucic amide, hexamethylene bisoleamide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacamide. Specific examples of fatty acid ester amides include stearamidoethyl stearate. Specific examples of aromatic bisamides include m-xylene bisstearic acid amide, m-xylene bishydroxystearic acid amide, N,N'-distearylisophthalic acid amide, etc. These amide lubricants may be used alone or in combination of two or more.

In the present invention, it is preferred that in addition to saturated fatty acid amides, the various amide-based lubricants also contain unsaturated fatty acid amides. This can further improve the moldability of the battery packaging material when it is not exposed to high temperatures and the continuous production of the battery. The mechanism is not yet clear, but it can be considered as follows. That is, unsaturated fatty acid amides have double bonds in their molecular structure, and when the molecules form an association body, they form a structure in which olefin chains overlap. Therefore, unsaturated fatty acid amides are relatively easy to move inside the sealing layer, easily seep out on the surface of the sealing layer, and easily exhibit slippery properties. On the other hand, saturated fatty acid amides do not have double bonds in their molecular structure and are straight-chain. When the molecules form an association body, they form a bulky structure (especially when the number of carbon atoms is 18 or more). Therefore, they are not easy to seep out on the surface of the sealing layer when stored at high temperatures, and are not easy to exhibit slippery properties. As a speculation, it can be considered that unsaturated fatty acid amides and saturated fatty acid amides form an association body with moderate exudation and slipperiness through association. As a second hypothesis, it is believed that the unsaturated fatty acids first seep out to form a first layer on the surface of the sealant layer, and then the saturated fatty acids that seep out are formed as a second layer between the first layer and the sealant layer, thereby suppressing further seepage of the unsaturated fatty acids that cause the white powder problem.

Regarding the carbon number of the saturated fatty acid amide, the amount of weight loss by heating in the temperature range of about 230 to 280°C, where the resin (polypropylene, etc.) forming the sealing layer 4 is melt-extruded and processed, reaches about 50% or more when the carbon number is less than 18. From the perspective of content management, it is desirable to have 18 or more. Furthermore, as described above, since saturated fatty acids suppress excessive exudation of the lubricant (any of the above assumptions), it is desirable to have a carbon number of about 22, such as behenic acid amide. From the perspective of further improving moldability and continuous production of batteries, erucic acid amide is particularly preferred as the unsaturated fatty acid amide. One unsaturated fatty acid amide can be used alone or in combination of two or more.

In the battery packaging material of the present invention, the total content of saturated fatty acid amides present in the sealant layer 4 (on both the surface and the interior) is preferably 20 ppm or more, more preferably about 100 to 1000 ppm, even more preferably about 200 to 700 ppm, and particularly preferably about 600 to 900 ppm, based on mass in the sealant layer 4. Furthermore, when the sealant layer 4 contains unsaturated fatty acid amides, the total content of unsaturated fatty acid amides present in the sealant layer 4 (on both the surface and the interior) is preferably 300 ppm or more, more preferably about 300 to 2000 ppm, and even more preferably about 500 to 1500 ppm, based on mass in the sealant layer 4. These values represent the total content, assuming that the saturated fatty acid amides or unsaturated fatty acid amides present on the surface and the interior of the sealant layer 4 are all present in the sealant layer 4. For example, when an amide-based lubricant is blended with the polyolefin resin forming the sealant layer 4, the content ratios of the saturated fatty acid amide or the unsaturated fatty acid amide in the sealant layer 4 are blended so as to achieve the above-mentioned values, and the content ratios of the saturated fatty acid amide or the unsaturated fatty acid amide present on the surface and inside the sealant layer 4 are also adjusted to the above-mentioned values.

In the battery packaging material of the present invention, when an adhesive resin layer 5 is laminated, the total content of saturated fatty acid amides present in the sealant layer 4 (both on the surface and inside) and the adhesive resin layer 5 is preferably 20 ppm or more, more preferably about 100 to 1000 ppm, even more preferably about 200 to 700 ppm, and particularly preferably about 600 to 900 ppm, based on mass in the sealant layer 4 and the adhesive resin layer 5. Furthermore, when at least one of the sealant layer 4 and the adhesive resin layer 5 contains an unsaturated fatty acid amide, the total content of unsaturated fatty acid amides present in the sealant layer 4 (both on the surface and inside) and the adhesive resin layer 5 is preferably 300 ppm or more, more preferably about 300 to 2000 ppm, and even more preferably about 500 to 1500 ppm, based on mass in the sealant layer 4 and the adhesive resin layer 5. In addition, these values are the sum totals of the content ratios assuming that the saturated fatty acid amide or unsaturated fatty acid amide present on the surface and inside of the sealant layer 4 and in the adhesive resin layer 5 are all present in the sealant layer 4 and the adhesive resin layer 5. For example, when an amide-based lubricant is added to the polyolefin resin forming the sealant layer 4 and/or the adhesive resin layer 5, the sealant layer 4 and the adhesive resin layer 5 are formed by adding them so that the sum total of the content ratios of the saturated fatty acid amide or unsaturated fatty acid amide in the sealant layer 4 and/or the adhesive resin 5 becomes the above-mentioned values, and the sum total of the content ratios of the saturated fatty acid amide or unsaturated fatty acid amide present on the surface and inside of the sealant layer 4 and in the adhesive resin layer 5 also becomes the above-mentioned values.

In the battery packaging material of the present invention, the total content of the various amide lubricants in the sealant layer 4 is preferably 400 ppm or more, more preferably approximately 600 to 2400 ppm, even more preferably approximately 800 to 2200 ppm, and particularly preferably approximately 1800 to 2100 ppm, based on mass. This value represents the content assuming that the various amide lubricants present on the surface and within the sealant layer 4 are present in the entirety of the sealant layer 4. For example, if an amide lubricant is incorporated into the resin forming the sealant layer 4, the total content of the various amide lubricants in the sealant layer 4 is the aforementioned value, and the total content of the various amide lubricants present on the surface and within the sealant layer also reaches the aforementioned value. Similarly, if an amide lubricant is applied to the surface of the sealant layer 4, the total amount applied is the aforementioned value, and the total content of the various amide lubricants present on the surface and within the sealant layer also reaches the aforementioned value. Depending on the type of resin forming the sealing layer 4, there is a saturated lubricant amount. Furthermore, the amount of amide lubricant that seeps out onto the surface also varies depending on the thickness of these layers. Generally speaking, the amount of amide lubricant that seeps out onto the surface of the sealing layer 4 increases as the thickness increases. Therefore, as the thickness of these layers increases, the concentration of amide lubricant contained in these layers is adjusted to decrease.

Furthermore, in the battery packaging material of the present invention, when an adhesive resin layer 5 is laminated, the total content of the various amide lubricants in the sealant layer 4 and the adhesive resin layer 5 is preferably 400 ppm or more, more preferably about 600 to 2400 ppm, even more preferably about 800 to 2200 ppm, and particularly preferably about 1800 to 2100 ppm, based on mass. This value represents the total content of the various amide lubricants present on the surface and interior of the sealant layer 4 and within the adhesive resin layer 5, assuming that all of the amide lubricants present in the sealant layer 4 and the adhesive resin layer 5 are present in the sealant layer 4 and the adhesive resin layer 5. For example, when an amide lubricant is incorporated into the resin forming the sealant layer 4 and the adhesive resin layer 5, by incorporating the amide lubricant so that the total content of the various amide lubricants in the sealant layer 4 and the adhesive resin layer 5 reaches the above value, the total content of the various amide lubricants present on the surface and interior of the sealant layer and the adhesive resin layer 5 also reaches the above value. Similarly, when applying an amide lubricant to the surface of the sealant layer 4, by adjusting the applied amount so that the total amount reaches the aforementioned value, the total content ratio of the various amide lubricants present on the surface and interior of the sealant layer 4 and in the adhesive resin layer 5 also reaches the aforementioned value. Depending on the types of resins forming the sealant layer 4 and the adhesive resin layer 5, there is a saturated lubricant amount. Furthermore, the amount of amide lubricant that seeps onto the surface also varies depending on the thickness of these layers. Generally speaking, the amount of amide lubricant that seeps onto the surface of the sealant layer 4 increases as the thickness increases. Therefore, as the thickness of these layers increases, the concentration of the amide lubricant in these layers is adjusted to decrease.

[Adhesive resin layer 5]

In the battery packaging material of the present invention, the adhesive resin layer 5 is a layer provided between the metal layer 3 and the sealant layer 4, as needed, to securely bond them. As described above, in the battery packaging material of the present invention, the adhesive resin layer 5 may contain a variety of amide-based lubricants. The type and amount of amide-based lubricants that may be contained in the adhesive resin layer 5 are as described above in the section "Sealant Layer 4."

The adhesive resin layer 5 is formed of an adhesive capable of bonding the metal layer 3 and the sealing layer 4. Regarding the adhesive used to form the adhesive resin layer 5, its bonding mechanism, the type of adhesive component, etc. are the same as those for the adhesive resin layer 2 described above. As the adhesive component used in the adhesive resin layer 5, a polyolefin resin is preferably used, a carboxylic acid-modified polyolefin is more preferably used, and a carboxylic acid-modified polypropylene is particularly preferably used.

The thickness of the adhesive resin layer 5 is, for example, 2 to 50 μm, preferably 15 to 30 μm.

The total thickness of the sealing layer 4 and the adhesive resin layer 5 can be appropriately selected, and is preferably about 20 to 100 μm, more preferably about 25 to 80 μm, and even more preferably about 30 to 60 μm.

3. Method for manufacturing battery packaging materials

The method for producing the battery packaging material of the present invention is not particularly limited as long as a laminated body in which layers having predetermined compositions are laminated is obtained. For example, the following method can be exemplified.

First, a laminate (hereinafter sometimes referred to as "laminate A") is formed by sequentially laminating a base material layer 1, an adhesive resin layer 2, and a metal layer 3. The laminate A can be formed by applying an adhesive to form the adhesive resin layer 2 onto the base material layer 1 or, if necessary, onto the metal layer 3 that has undergone a surface treatment by a chemical conversion method by a coating method such as extrusion, gravure printing, or roll coating, and then drying the adhesive. The metal layer 3 or base material layer 1 is then laminated and the adhesive resin layer 2 is cured by a dry lamination method.

Next, the sealing layer 4 is laminated on the metal layer 3 of the laminate A. When the sealing layer 4 is laminated directly on the metal layer 3, the resin component constituting the sealing layer 4 can be applied to the metal layer 3 of the laminate A by gravure printing, roll coating, or the like. In addition, when the adhesive resin layer 5 is provided between the metal layer 3 and the sealing layer 4, for example, there can be mentioned (1) a method of laminating the adhesive resin layer 5 and the sealing layer 4 on the metal layer 3 of the laminate A by co-extrusion (coextrusion lamination method); (2) a method of forming a laminate having the adhesive resin layer 5 and the sealing layer 4 laminated thereon and laminating the laminate on the metal layer 3 of the laminate A by heat lamination; (3) a method of laminating an adhesive for forming the adhesive resin layer 5 on the metal layer 3 of the laminate A by extrusion or solution coating, drying at high temperature and then further firing, and laminating the sealing layer 4 pre-formed in the form of a sheet on the adhesive resin layer 5 by heat lamination; (4) a method of pouring a molten adhesive resin layer 5 between the metal layer 3 of the laminate A and the sealing layer 4 pre-formed in the form of a sheet and bonding the laminate A and the sealing layer 4 via the adhesive resin layer 5 (sandwich lamination method), etc. Furthermore, in order to strengthen the adhesion between the adhesive resin layer 2 and the adhesive resin layer 5 provided as needed, the adhesive resin layer 2 may be subjected to a heat treatment using a hot roll contact method, a hot air method, a near infrared method or a far infrared method. Conditions for such a heat treatment include, for example, a temperature of 150 to 250° C. for several seconds to one minute.

In the battery packaging material of the present invention, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, sandblasting, oxidation treatment, or ozone treatment, as necessary, in order to improve or stabilize film forming properties, lamination processing, and suitability for secondary processing of the final product (bagging, embossing molding).

4. Application of battery packaging materials

The battery packaging material of the present invention is used as a packaging material for sealing and storing battery elements such as a positive electrode, a negative electrode, and an electrolyte.

Specifically, a battery element comprising at least a positive electrode, a negative electrode, and an electrolyte is wrapped with the battery packaging material of the present invention, with the metal terminals connected to the positive and negative electrodes protruding outward, in a manner that forms a flange portion (an area where the sealing layers contact each other) around the periphery of the battery element, and the sealing layers of the flange portion are heat-sealed to each other, thereby providing a battery using the battery packaging material. Furthermore, when the battery element is housed in the battery packaging material of the present invention, the sealed portion of the battery packaging material of the present invention is positioned on the inner side (the surface in contact with the battery element).

The battery packaging material of the present invention can be used for either primary or secondary batteries, preferably secondary batteries. There are no particular limitations on the types of secondary batteries to which the battery packaging material of the present invention is applicable. Examples include lithium-ion batteries, lithium-ion polymer batteries, lead-acid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver-oxide-zinc batteries, metal-air batteries, multivalent cation batteries, capacitors, and the like. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are preferred as suitable applications for the battery packaging material of the present invention.

Example

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

Examples 1 to 12 and Comparative Examples 1 to 4

＜Manufacturing of battery packaging materials＞

Aluminum foil (40 μm thick) serving as a metal layer was chemically converted on both sides. A nylon film serving as a base layer, having the thickness listed in Table 1, was adhered to one of the chemically converted surfaces via a dry lamination method with a polyester adhesive such that the adhesive resin layer had a thickness of approximately 3 μm. Subsequently, in Examples 1 to 6 and Comparative Examples 1 and 2, a carboxylic acid-modified polypropylene having the thickness listed in Table 1, serving as an adhesive resin layer, and a polypropylene having the thickness listed in Table 1 and containing an amide lubricant in the amount listed in Table 1, serving as a sealant layer, were coextruded onto the other chemically converted surface of the aluminum foil, resulting in a laminate consisting of base layer/adhesive resin layer/aluminum foil/adhesive resin layer/sealant layer. On the other hand, in Examples 7-12 and Comparative Examples 3-4, a polypropylene having the thickness and the content of an amide lubricant indicated in Table 1 as a sealant layer was laminated onto the other chemically converted surface of the aluminum foil via a dry lamination method. This resulted in a laminate consisting of substrate layer/adhesive resin layer/aluminum foil/adhesive resin layer/sealant layer. Each battery packaging material was manufactured at a temperature of 20-30°C and a relative humidity of 40-60%. The chemical conversion treatment was performed using an aqueous solution containing a phenolic resin, a chromium fluoride compound, and phosphoric acid as the treatment solution. The coating was applied by roll coating, and the film was fired at a temperature of 180°C or higher. The chromium coating amount was 3 mg/ ^m² (dry weight). The amide lubricant used is as follows.

Unsaturated fatty acid amide: erucamide

Saturated fatty acid amide: behenamide

(Store at room temperature or 40°C)

The battery packaging materials of Examples 1 to 12 and Comparative Examples 1 to 4 were left at room temperature (25°C) or 40°C and 50% relative humidity for 14 days, and then subjected to the following friction test, formability test, and white powder confirmation test.

(Friction test)

The friction test is measured by a method based on JIS K7125. First, each battery packaging material obtained above is cut into a sample of 80×200 mm. Then, the samples are overlapped in such a way that the surfaces of the sealing layers are facing each other, and a weight (200 g) is placed thereon. Rubber is affixed to the bottom surface of the weight so that the sample and the weight are also tightly fitted so as not to slide. Then, the weight is pulled at a speed of 100 mm/min, the dynamic friction force (N) is measured, and the dynamic friction force is divided by the force in the normal direction of the weight (1.96 N) to calculate the coefficient of dynamic friction. The results are evaluated according to the following benchmarks. The results are shown in Table 1.

○: Dynamic friction coefficient is 0.3 or less

△: Dynamic friction coefficient is more than 0.3 and less than 0.7

×: Dynamic friction coefficient exceeds 0.7

(Formability test)

Each battery packaging material obtained above was cut into 80×120 mm squares to make samples. Using a forming mold (female mold) with a diameter of 30×55 mm and a corresponding forming mold (male mold), the sample was cold-formed at an extrusion force of 0.24 MPa from a forming depth of 0.5 mm in units of 0.5 mm. For the cold-formed samples, the deepest forming depth at which no wrinkles occurred in all 10 samples and no pinholes or cracks were generated in the aluminum foil was taken as the critical forming depth of the sample. From this critical forming depth, the formability of the battery packaging material was evaluated according to the following criteria. The results are shown in Table 1.

○: Critical forming depth exceeds 6.5mm

△: Critical forming depth 5.0mm～6.5mm

×: Critical forming depth is less than 5.0 mm

(Confirmation test of white powder)

A black drawing paper cut into 5 x 13 cm pieces was folded in half and a predetermined area (1 m ² ) of the sealed surface of each battery packaging material obtained above was firmly rubbed to adhere white powder (leaked lubricant). The degree of adhesion was visually confirmed. The results were evaluated according to the following criteria. The results are shown in Table 1.

○: Almost no adhesion

△: Slightly adhered

×: Significant adhesion

[Table 1]

As shown in the results in Table 1, the battery packaging materials of Examples 1 to 12, which used behenic acid amide, a saturated fatty acid amide having 22 carbon atoms, and erucic acid amide, an unsaturated fatty acid amide having 22 carbon atoms, as amide-based lubricants, showed good results or no practical problems in all the friction tests, moldability tests, and white powder confirmation tests, not only when stored at room temperature but also when stored at a high temperature of 40°C.

On the other hand, the battery packaging material of Comparative Example 1, which used only erucamide as the amide lubricant, exhibited significantly poorer friction and moldability test results compared to Examples 1 to 6 when stored at a high temperature of 40°C. Furthermore, the battery packaging material of Comparative Example 2, which used only behenamide as the amide lubricant, exhibited poorer friction coefficient and moldability than Examples 1 to 6.

Furthermore, in Comparative Example 3, in which the sealant layer thickness was increased compared to Comparative Example 1, which used only erucamide as the amide lubricant, the friction coefficient and moldability in the white powder confirmation test during room temperature storage and during high-temperature storage were inferior to those of Examples 7 to 12 of the same thickness. The battery packaging material of Comparative Example 4, in which only behenamide was used as the amide lubricant, exhibited inferior friction coefficient and moldability compared to those of Examples 7 to 12 of the same thickness.

Explanation of symbols

1. Base material layer

2 Adhesive resin layer

3 Metal Layer

4 Sealing layer

5. Adhesive resin layer

Claims (10)

1. A packaging material for batteries, characterized in that: A laminate comprising at least a substrate layer, a metal layer, and a sealing layer stacked sequentially. The sealing layer contains various fatty acid amide-based lubricants. The various fatty acid amide lubricants include saturated fatty acid amides and unsaturated fatty acid amides. The total content of the various fatty acid amide lubricants in the sealing layer, by weight, is 800–2200 ppm. The total content of the saturated fatty acid amides present in the sealing layer, on a mass basis, is 300 to 900 ppm. The saturated fatty acid amide is betaine amide. The unsaturated fatty acid amide is erucamide. 2. The battery packaging material as described in claim 1, characterized in that: The sealing layer is formed of polypropylene. 3. The battery packaging material as described in claim 1 or 2, characterized in that: An adhesive resin layer is laminated between the metal layer and the sealing layer. 4. The battery packaging material as described in claim 3, characterized in that: The adhesive resin layer is formed of acid-modified polypropylene. 5. The battery packaging material as described in claim 3, characterized in that: The combined thickness of the adhesive resin layer and the sealing layer is 20–100 μm. 6. The battery packaging material as described in claim 3, characterized in that: The total content of the saturated fatty acid amide present in the adhesive resin layer and the sealing layer is 20 ppm or more. 7. The battery packaging material as described in claim 1 or 2, characterized in that: The metal layer is formed of aluminum foil. 8. A battery, characterized in that: The battery packaging material according to any one of claims 1 to 7 contains a battery element having at least a positive electrode, a negative electrode, and an electrolyte. 9. A method for manufacturing a battery, characterized in that: This includes the process of packaging battery components, which have at least a positive electrode, a negative electrode, and an electrolyte, using battery packaging materials. The battery packaging material comprises a laminate consisting of at least a substrate layer, a metal layer, and a sealing layer stacked sequentially. The sealing layer contains various fatty acid amide-based lubricants. The various fatty acid amide lubricants include saturated fatty acid amides and unsaturated fatty acid amides. The total content of the various fatty acid amide lubricants in the sealing layer, by weight, is 800–2200 ppm. The total content of the saturated fatty acid amides present on both the surface and interior of the sealing layer, on a mass basis, is 300–900 ppm. The saturated fatty acid amide is betaine amide. The unsaturated fatty acid amide is erucamide. 10. The use of a laminated body as a battery packaging material, characterized in that: The laminate consists of at least a substrate layer, a metal layer, and a sealing layer stacked sequentially. The sealing layer contains various fatty acid amide-based lubricants. The various fatty acid amide lubricants include saturated fatty acid amides and unsaturated fatty acid amides. The total content of the various fatty acid amide lubricants in the sealing layer, by weight, is 800–2200 ppm. The total content of the saturated fatty acid amides present on both the surface and interior of the sealing layer, on a mass basis, is 300–900 ppm. The saturated fatty acid amide is betaine amide. The unsaturated fatty acid amide is erucamide.