JP2017069203A - Battery packaging material and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery packaging material in which deterioration of electrolytic solution resistance is effectively suppressed even when stretched at a high stretch ratio. SOLUTION: The laminated body comprises at least a base material layer, a barrier layer, an adhesive resin layer, and a heat-fusible resin layer in order from the outside, and the adhesive resin layer is a thermosetting modified polyolefin. When the laminate is made of a cured product of a resin and stretched in a direction perpendicular to the thickness direction at a stretching ratio of 150%, a difference in brightness measured from the heat-fusible resin layer side of the laminate before and after the stretching. A battery packaging material having a ΔL value of 35 or less. [Selection diagram] None

Description

  The present invention relates to a battery packaging material and a battery.

  Conventionally, various types of batteries have been developed. In these batteries, a battery element composed of an electrode, an electrolyte and the like needs to be sealed with a packaging material or the like. Metal packaging materials are frequently used as battery packaging materials.

  In recent years, as electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like have improved performance, batteries having various shapes have been demanded. The battery is also required to be thin and light. However, it is difficult to follow the diversification of battery shapes with metal packaging materials that have been widely used in the past. Further, since it is made of metal, there is a limit to reducing the weight of the packaging material.

  Therefore, as a battery packaging material that can be easily processed into various shapes and can be made thinner and lighter, there is a film-like laminate in which a base material layer / barrier layer / heat-sealable resin layer are sequentially laminated. Proposed.

  For example, Patent Document 1 discloses a battery case including a biaxially stretched polyamide film layer as an outer layer, an unstretched thermoplastic resin film layer as an inner layer, and an aluminum foil layer disposed between the two film layers. A packaging material is disclosed.

JP 2008-287971 A

  Conventionally, a layer formed of a modified polyolefin resin has been laminated on the surface of the barrier layer on the heat-fusible resin layer side for the purpose of improving the adhesion between the barrier layer and the heat-fusible resin layer. is there.

  On the other hand, in recent years, high formability (deep molding) is required for battery packaging materials in order to increase the capacity of batteries. For example, a large battery such as a vehicle battery is increasingly required to have a high moldability, and a battery packaging material made of a laminate as described above is used. In a battery packaging material used for a battery that requires high moldability, when a deep space for accommodating a battery element is formed by molding, it may be stretched to a maximum draw ratio of 120% or more.

  As a result of extensive studies by the inventor, when the battery packaging material in which the modified polyolefin resin is laminated on the heat-fusible resin layer side is stretched at a high draw ratio, it is located on the heat-fusible resin layer side. A new problem has been found that the modified polyolefin resin is easily whitened.

  Such whitening is the result of the micro-cracking of the modified polyolefin resin appearing white due to the significant stretching of the battery packaging material. For this reason, when whitening arises in the packaging material for batteries, there exists a problem that electrolyte solution resistance falls.

  The present invention has been made in view of such problems. That is, the main object of the present invention is to provide a battery packaging material in which a decrease in electrolytic solution resistance is effectively suppressed even when stretched at a high stretch ratio.

  The present inventor has intensively studied to solve the above problems. As a result, in the battery packaging material composed of a laminate including a base material layer, a barrier layer, an adhesive resin layer, and a heat-fusible resin layer in order from the outside, the adhesive resin layer has a thermosetting property. Lightness measured from the heat-fusible resin layer side of the laminate before and after stretching when the laminate is stretched at a stretch ratio of 150% in the direction perpendicular to the thickness direction. It has been found that when the value of the difference ΔL is 35 or less, a decrease in the electrolytic solution resistance is effectively suppressed even when the difference ΔL is stretched at a high stretch ratio. The present invention has been completed by further studies based on these findings.

That is, this invention provides the packaging material for batteries of the aspect hung up below, its manufacturing method, and a battery.
Item 1. At least comprising a laminate comprising a base material layer, a barrier layer, an adhesive resin layer, and a heat-fusible resin layer in order from the outside,
The adhesive resin layer is made of a cured product of a thermosetting modified polyolefin resin,
When the laminate is stretched in a direction perpendicular to the thickness direction at a stretch ratio of 150%, the value of the brightness difference ΔL measured from the heat-fusible resin layer side of the laminate before and after the stretching is 35 or less. A battery packaging material.
Item 2. Item 4. The battery packaging material according to Item 1, wherein the adhesive resin layer has a thickness of 30 µm or less. Item 3. Item 3. The battery packaging material according to Item 1 or 2, wherein the thermosetting modified polyolefin resin includes a modified polyolefin resin modified with an unsaturated carboxylic acid or an acid anhydride thereof.
Item 4. Item 4. The battery packaging material according to any one of Items 1 to 3, wherein the thermosetting modified polyolefin resin is thermosetting modified polypropylene.
Item 5. Item 5. The battery packaging material according to any one of Items 1 to 4, wherein the thermosetting acid-modified polyolefin resin further comprises a curing agent.
Item 6. Item 6. The battery packaging material according to any one of Items 1 to 5, wherein a melting point of the adhesive resin layer is lower than a melting point of the heat-fusible resin layer.
Item 7. Item 7. The battery packaging material according to any one of Items 1 to 6, wherein the barrier layer is formed of an aluminum foil.
Item 8. Item 8. The battery packaging material according to any one of Items 1 to 7, wherein the battery packaging material is for high molding stretched to a maximum stretching ratio of 120% or more.
Item 9. Item 10. The battery packaging material according to any one of Items 1 to 8, wherein the adhesive resin layer has a hardness measured by a nanoindentation method of 10 MPa or more and 300 MPa or less.
Item 10. A battery in which a battery element including a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the battery packaging material according to any one of Items 1 to 9.

  According to the battery packaging material of the present invention, it is possible to provide a battery packaging material in which a decrease in resistance to electrolytic solution is effectively suppressed even when the battery packaging material is stretched at a high stretch ratio.

It is a schematic sectional drawing of an example of the packaging material for batteries which concerns on this invention.

  The battery packaging material of the present invention is an adhesive resin in a battery packaging material comprising at least a base material layer, a barrier layer, an adhesive resin layer, and a heat-fusible resin layer in order from the outside. When the layer is made of a cured product of a thermosetting modified polyolefin resin and the laminate is stretched at a stretch ratio of 150% in a direction perpendicular to the thickness direction, the heat-fusible resin layer of the laminate before and after the stretching. The value of the brightness difference ΔL measured from the side is 35 or less. Hereinafter, the battery of the present invention in which the battery packaging material of the present invention, the production method thereof, and the battery element are sealed with the battery packaging material of the present invention will be described in detail with reference to FIG.

  In the present specification, the numerical range indicated by “to” means “above” or “below”, except for the portions specified as “above” or “below”. For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

1. Laminated structure of battery packaging material The battery packaging material of the present invention, for example, as shown in FIG. 1, is at least a base layer 1, a barrier layer 3, an adhesive resin layer 5, and a heat-fusible layer in order from the outside. It consists of a laminated body provided with the resin layer 4 in this order. In the battery packaging material, the base material layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. That is, at the time of assembling the battery, the heat-fusible resin layer 4 of the battery packaging material is placed inside the battery so that the battery element is wrapped with the battery packaging material, and the heat-fusibility located at the periphery of the battery element. The battery element is sealed by thermally welding the resin layers 4 to seal the battery element.

  The battery packaging material of the present invention only needs to include at least the base material layer 1, the barrier layer 3, the adhesive resin layer 5, and the heat-fusible resin layer 4, and may have other layers. Good. For example, as will be described later, in the battery packaging material of the present invention, as shown in FIG. 1, for example, as shown in FIG. An adhesive layer 2 may be provided.

  The thickness of the laminate constituting the battery packaging material of the present invention is not particularly limited, but is preferably 160 μm or less from the viewpoint of exhibiting high electrolytic solution resistance while reducing the thickness of the laminate as much as possible. More preferably, 35 micrometers-155 micrometers, More preferably, 45 micrometers-120 micrometers are mentioned.

2. Whitening of battery packaging materials

As described above, in recent years, high formability (deep molding) is required for battery packaging materials in order to increase the capacity of batteries. For example, a large battery such as a vehicle battery (for example, having a surface area of 400 cm ² or more) is increasingly required to have high moldability, and a battery packaging material made of a laminate as described above is used. . In a battery packaging material used for a battery that requires high moldability, when a deep space for accommodating a battery element is formed by molding, it may be stretched to a maximum draw ratio of 120% or more. In such a high-molding ionization packaging material, a battery packaging material in which a modified polyolefin resin is laminated on the heat-fusible resin layer side is used at a high draw ratio (for example, a maximum draw ratio of 120% or more). A new problem has been found that, when stretched, the modified polyolefin resin located on the heat-fusible resin layer side is whitened. Such whitening is the result of the micro-cracking of the modified polyolefin resin appearing white due to the significant stretching of the battery packaging material. For this reason, when whitening arises in the packaging material for batteries, there exists a problem that electrolyte solution resistance falls.

  On the other hand, in the battery packaging material of the present invention, at least a base material layer, a barrier layer, an adhesive resin layer, and a heat-fusible resin layer are laminated in this order in an adhesive resin. When the layer is formed of a cured product of a thermosetting modified polyolefin resin and the laminate is stretched at a stretch ratio of 150% in a direction perpendicular to the thickness direction, the laminate is thermally fused before and after the stretching. Since the value of the lightness difference ΔL measured from the conductive resin layer side is set to 35 or less, even when the film is stretched at a high stretch ratio, a decrease in electrolytic solution resistance is effectively suppressed.

  Even when the film is stretched at a higher stretch ratio, the value of the brightness difference ΔL is preferably 33 or less, more preferably 32 or less, and still more preferably, from the viewpoint of effectively suppressing the decrease in resistance to electrolytic solution. Is 31 or less, more preferably 30 or less, further preferably 25 or less, more preferably 20 or less, still more preferably 15 or less, and still more preferably 10 or less.

In the present invention, the brightness difference ΔL is a value measured as follows. Using a tensile tester, the battery packaging material is pulled at a distance of 50 mm / minute between grips and stretched by 150%. Next, for the battery packaging material after stretching, the lightness L ^* value is measured from the heat-fusible resin layer side using a microspectrometer. Similarly, the lightness L ^* value of the battery packaging material before stretching is measured. The brightness difference ΔL is calculated from these brightness L ^* values.

3. Composition of each layer forming base material for battery [base material layer 1]
In the battery packaging material of the present invention, the base material layer 1 is a layer located on the outermost layer side, and is a layer located on the outermost layer when a surface coating layer described later is not formed. The material for forming the base material layer 1 is not particularly limited as long as it has insulating properties. Examples of the material for forming the base material layer 1 include polyester, polyamide, epoxy resin, acrylic resin, fluorine resin, polyurethane, silicon resin, phenol resin, polyetherimide, polyimide, and a mixture or copolymer thereof. Can be mentioned.

  Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, copolymerized polyester mainly composed of ethylene terephthalate, butylene terephthalate as a repeating unit. Examples thereof include a copolymer polyester mainly used. The copolymer polyester mainly composed of ethylene terephthalate is a copolymer polyester that polymerizes with ethylene isophthalate mainly composed of ethylene terephthalate (hereinafter, polyethylene (terephthalate / isophthalate)). Abbreviated), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate) And polyethylene (terephthalate / decanedicarboxylate). In addition, as a copolymer polyester mainly composed of butylene terephthalate as a repeating unit, specifically, a copolymer polyester that polymerizes with butylene isophthalate having butylene terephthalate as a repeating unit (hereinafter referred to as polybutylene (terephthalate / isophthalate)). For example), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), polybutylene (terephthalate / decanedicarboxylate), polybutylene naphthalate and the like. These polyesters may be used individually by 1 type, and may be used in combination of 2 or more type. Polyester has the advantage of being excellent in electrolytic solution resistance and less likely to cause whitening due to the adhesion of the electrolytic solution, and is suitably used as a material for forming the base material layer 1.

  Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and a copolymer of nylon 6 and nylon 66; terephthalic acid and / or isophthalic acid Nylon 6I, Nylon 6T, Nylon 6IT, Nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid) and the like, and polymetaxylylene azide Polyamide containing aromatics such as Pamide (MXD6); Alicyclic polyamides such as Polyaminomethylcyclohexyl Adipamide (PACM6); and Lactam components and isocyanate components such as 4,4′-diphenylmethane-diisocyanate are copolymerized Polyamide, copolymer Polyester amide copolymer and polyether ester amide copolymer is a copolymer of a polyamide and a polyester and polyalkylene ether glycol; copolymers thereof, and the like. These polyamides may be used individually by 1 type, and may be used in combination of 2 or more type. The stretched polyamide film is excellent in stretchability, can prevent whitening due to resin cracking of the base material layer 1 during molding, and is suitably used as a material for forming the base material layer 1.

  The base material layer 1 may be formed of a uniaxially or biaxially stretched resin film, or may be formed of an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, in particular, a biaxially stretched resin film has improved heat resistance by orientation crystallization, and thus is suitably used as the base material layer 1. Moreover, the base material layer 1 may be formed by coating the above-mentioned material on the barrier layer 3.

  Among these, as a resin film which forms the base material layer 1, Preferably nylon and polyester, More preferably, biaxially stretched nylon, biaxially stretched polyester, Most preferably, biaxially stretched nylon and biaxially stretched polyester are mentioned.

  The base material layer 1 can also be laminated with at least one of resin films and coatings of different materials in order to improve pinhole resistance and insulation when used as a battery package. Specific examples include a multilayer structure in which a polyester film and a nylon film are laminated, and a multilayer structure in which a biaxially stretched polyester and a biaxially stretched nylon are laminated. When making the base material layer 1 into a multilayer structure, each resin film may be adhere | attached through an adhesive agent, and may be laminated | stacked directly without an adhesive agent. In the case of bonding without using an adhesive, for example, a method of bonding in a hot melt state such as a co-extrusion method, a sand lamination method, or a thermal laminating method can be mentioned. Moreover, when making it adhere | attach through an adhesive agent, the adhesive agent to be used may be a two-component curable adhesive, or a one-component curable adhesive. Furthermore, the adhesive mechanism of the adhesive 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, an electron beam curable type, an ultraviolet curable type, and the like. As an adhesive component, polyester resin, polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin, polyolefin resin, polyvinyl acetate resin, cellulose resin, (meth) acrylic resin Resins, polyimide resins, amino resins, rubbers, and silicon resins can be used.

  The base material layer 1 may be reduced in friction in order to improve moldability. In the case of reducing the friction of the base material layer 1, the friction coefficient of the surface is not particularly limited, but for example, 1.0 or less can be mentioned. In order to reduce the friction of the base material layer 1, for example, mat treatment, formation of a thin film layer of a lubricant, a combination thereof, and the like can be given.

  As the matting treatment, a matting agent is added to the base material layer 1 in advance to form irregularities on the surface, a transfer method by heating or pressurizing with an embossing roll, a surface is mechanically dry or wet blasting, or a file. There is a way to troll. Examples of the matting agent include fine particles having a particle size of about 0.5 nm to 5 μm. The material of the matting agent is not particularly limited, and examples thereof include metals, metal oxides, inorganic substances, and organic substances. The shape of the matting agent is not particularly limited, and examples thereof include a spherical shape, a fiber shape, a plate shape, an indeterminate shape, and a balloon shape. Specific examples of the matting agent include talc, silica, graphite, kaolin, montmorilloid, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, and aluminum oxide. , Neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, High melting point nylon, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel and the like can be mentioned. These matting agents may be used individually by 1 type, and may be used in combination of 2 or more type. Among these matting agents, silica, barium sulfate, and titanium oxide are preferable from the viewpoint of dispersion stability and cost. The matting agent may be subjected to various surface treatments such as insulation treatment and high dispersibility treatment on the surface.

  The thin film layer of the lubricant can be formed by depositing the lubricant on the surface of the base material layer 1 by bleeding out to form a thin layer, or by laminating the lubricant on the base material layer 1. The lubricant is not particularly limited. For example, amide-based lubricant, metal soap, hydrophilic silicone, silicone grafted acrylic, silicone grafted epoxy, silicone grafted polyether, silicone grafted polyester, block silicone Examples thereof include acrylic copolymers, polyglycerol-modified silicone, and paraffin. These lubricants may be used individually by 1 type, and may be used in combination of 2 or more type.

  As thickness of the base material layer 1, 10-50 micrometers, for example, Preferably 15-30 micrometers is mentioned.

[Surface coating layer]
In the battery packaging material of the present invention, a surface coating layer (not shown) provided as necessary is a layer located on the outer side (outermost layer) of the base material layer 1 when the battery is assembled. In the present invention, the surface coating layer is formed of, for example, a two-component curable resin for the purpose of mainly imparting electrolytic solution resistance, slipperiness, and friction resistance to the battery packaging material. The two-part curable resin for forming the surface coating layer is not particularly limited as long as it has an electrolytic solution resistance. For example, the two-part curable urethane resin, the two-part curable polyester resin, and the two-part curable type An epoxy resin etc. are mentioned. Moreover, you may mix | blend a matting agent with a surface coating layer for the purpose of providing the designability.

  Examples of the matting agent include those exemplified in the above [Base Layer 1].

  The method for forming the surface coating layer is not particularly limited, and examples thereof include a method of applying a two-component curable resin for forming the surface coating layer to one surface of the base material layer 1. When the matting agent is blended, the matting agent may be added to the two-component curable resin, mixed, and then applied.

  The surface coating layer is preferably formed thin enough to exhibit resistance to an electrolytic solution, and the thickness is preferably 5 μm or less, more preferably 3 μm or less. From the viewpoint of resistance to electrolytic solution, the lower limit of the thickness of the surface coating layer is usually about 2 μm.

[Adhesive layer 2]
In the battery packaging material of the present invention, the adhesive layer 2 is a layer provided as necessary in order to adhere the base material layer 1 and the barrier layer 3.

  The adhesive layer 2 is formed of an adhesive that can bond the base material layer 1 and the barrier layer 3 together. 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 resin component of the adhesive that can be used to form the adhesive layer 2 include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolyester. Resin; Polyether adhesive; Polyurethane adhesive; Epoxy resin; Phenol resin resin; Polyamide resin such as nylon 6, nylon 66, nylon 12, copolymer polyamide; polyolefin, acid-modified polyolefin, metal-modified polyolefin, etc. Polyolefin resin; polyvinyl acetate resin; cellulose adhesive; (meth) acrylic resin; polyimide resin; urea resin, melamine resin and other amino resins; chloroprene rubber, nitrile rubber, styrene - rubbers such as butadiene rubber, silicone resin; fluorinated ethylene propylene copolymer, and the like. These adhesive components may be used individually by 1 type, and may be used in combination of 2 or more type. The combination mode of two or more kinds of adhesive components is not particularly limited. For example, as the adhesive component, a mixed resin of polyamide and acid-modified polyolefin, a mixed resin of polyamide and metal-modified polyolefin, polyamide and polyester, Examples thereof include a mixed resin of polyester and acid-modified polyolefin, and a mixed resin of polyester and metal-modified polyolefin. Among these, extensibility, durability under high humidity conditions, anti-hypertensive action, thermal deterioration-preventing action during heat sealing, etc. are excellent, and a decrease in laminate strength between the base material layer 1 and the barrier layer 3 is suppressed. From the viewpoint of effectively suppressing the occurrence of delamination, a polyurethane two-component curable adhesive; polyamide, polyester, or a blended resin of these with a modified polyolefin is preferable.

  The adhesive layer 2 may be multilayered with different adhesive components. When the adhesive layer 2 is multilayered with different adhesive components, from the viewpoint of improving the lamination strength between the base layer 1 and the barrier layer 3, the adhesive component disposed on the base layer 1 side is used as the base layer 1. It is preferable to select a resin excellent in adhesiveness and to select an adhesive component excellent in adhesiveness to the barrier layer 3 as an adhesive component disposed on the barrier layer 3 side. When the adhesive layer 2 is multilayered with different adhesive components, specifically, the adhesive component disposed on the barrier layer 3 side is preferably an acid-modified polyolefin, a metal-modified polyolefin, a polyester and an acid-modified polyolefin. And a resin containing a copolyester.

  About the thickness of the contact bonding layer 2, 2-50 micrometers, for example, Preferably it is 2-20 micrometers, More preferably, 3-15 micrometers is mentioned.

[Barrier layer 3]
In the battery packaging material, the barrier layer 3 is a layer that functions as a barrier layer for preventing water vapor, oxygen, light, and the like from entering the battery, in addition to improving the strength of the battery packaging material. Specific examples of the metal constituting the barrier layer 3 include aluminum, stainless steel, and titanium, and preferably aluminum. The barrier layer 3 can be formed by, for example, a metal foil, a metal vapor-deposited film, an inorganic oxide vapor-deposited film, a carbon-containing inorganic oxide vapor-deposited film, a film provided with these vapor-deposited films, etc. It is more preferable that it is formed of an aluminum foil. From the viewpoint of preventing generation of wrinkles and pinholes in the barrier layer 3 during the production of the battery packaging material, for example, annealed aluminum (JIS H4160: 1994 A8021H-O, JIS H4160: 1994 A8079H-O). JIS H4000: 2014 A8021P-O, JIS H4000: 2014 A8079P-O), and the like, more preferably formed of a soft aluminum foil.

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

  Further, the barrier layer 3 is subjected to chemical conversion treatment on at least one surface, preferably at least the surface on the side of the heat-fusible resin layer 4, more preferably both surfaces for stabilization of adhesion, prevention of dissolution and corrosion, and the like. Preferably it is. Here, the chemical conversion treatment is a treatment for forming an acid-resistant film on the surface of the barrier layer 3. 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 the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be included singly or in any combination of two or more. Also good.

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 hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer composed of the repeating units represented by the general formulas (1) to (4) is, for example, about 500 to about 1,000,000, preferably about 1000 to about 20,000.

  Further, as a chemical conversion treatment method for imparting corrosion resistance to the barrier layer 3, a phosphoric acid is coated with a metal oxide such as aluminum oxide, titanium oxide, cerium oxide, tin oxide, or barium sulfate fine particles dispersed therein. A method of forming a corrosion-resistant treatment layer on the surface of the barrier layer 3 by performing a baking treatment at 150 ° C. or higher is mentioned. Moreover, you may form the resin layer which crosslinked the cationic polymer with the crosslinking agent on the corrosion-resistant process 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 an aminated phenol polymer are combined is more preferable.

The amount of the acid-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. For example, if the chromate treatment is performed by combining a chromic acid compound, a phosphoric acid compound, and an 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 barrier layer 3. Is preferably about 1.0 to about 40 mg, and about 1 to about 200 mg, preferably about 5.0 to 150 mg of aminated phenol polymer.

  In the chemical conversion treatment, a solution containing a compound used for forming an acid-resistant film is applied to the surface of the barrier layer 3 by a bar coating method, a roll coating method, a gravure coating method, a dipping method or the like, and then the temperature of the barrier layer 3 is reached. Is performed by heating so as to be about 70 to 200 ° C. In addition, before the chemical conversion treatment is performed on the barrier layer 3, the barrier layer 3 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 process in this way, it is possible to perform the chemical conversion process on the surface of the barrier layer 3 more efficiently.

[Adhesive resin layer 5]
In the present invention, the adhesive resin layer 5 is a layer provided between the barrier layer 3 and the heat-fusible resin layer 4 for the purpose of improving the adhesion between the barrier layer 3 and the heat-fusible resin layer 4. It is. In the battery packaging material of the present invention, the adhesive resin layer 5 is formed of a cured product of a thermosetting modified polyolefin resin, and the laminate constituting the battery packaging material is perpendicular to the thickness direction. When the film is stretched at a stretch ratio of 150%, the value of the lightness difference ΔL measured from the heat-fusible resin layer 4 side of the laminate before and after the stretching is set to 35 or less.

  From the viewpoint of further effectively suppressing the above-mentioned whitening and improving the resistance to electrolytic solution while improving the adhesion between the barrier layer 3 and the heat-fusible resin layer 4, the adhesive resin layer 5 is made of nanoindene. The hardness measured by the tentation method is preferably about 10 to 300 MPa, more preferably about 15 to 200 MPa, and still more preferably about 20 to 150 MPa.

In the present invention, the hardness measured by the nanoindentation method of the adhesive resin layer 5 is a value measured as follows. Nanoindenter ("TriboIndenter TI950" manufactured by HYSITRON (Heiditron) Co., Ltd.) is used as the measuring device.Berkovich indenter (triangular pyramid) is used as the indenter of the nanoindenter. In this case, the indenter is applied to the surface of the adhesive resin layer of the battery packaging material (the surface where the adhesive resin layer is exposed and perpendicular to the stacking direction of each layer), and the load is applied from the surface over 10 seconds. The indenter is pushed into the adhesive resin layer up to 40 μN, held in that state for 5 seconds, and then unloaded for 10 seconds, with the maximum load P _max (μN) and the indentation area A (nm ² ) at the maximum depth. Used, the indentation hardness (MPa) is calculated from P _max / A.

  The thermosetting modified polyolefin resin preferably includes a modified polyolefin resin modified with an unsaturated carboxylic acid or an acid anhydride thereof. The modified polyolefin resin is not particularly limited as long as it is obtained by modifying a resin containing at least an olefin as a monomer unit. The thermosetting modified polyolefin resin preferably includes at least one of a thermosetting modified polyethylene resin and a thermosetting modified polypropylene resin, and more preferably includes a thermosetting modified polypropylene resin.

  The polyethylene resin to be modified can be composed of, for example, at least one of homopolyethylene and ethylene copolymer. The polypropylene resin to be modified can be composed of at least one of homopolypropylene and propylene copolymer, for example. Examples of the propylene copolymer include copolymers of propylene and other olefins such as an ethylene-propylene copolymer, a propylene-butene copolymer, and an ethylene-propylene-butene copolymer.

  The proportion of the propylene unit contained in the polypropylene resin to be modified is preferably about 50 mol% to 100 mol%, more preferably 80 mol% to 100 mol, from the viewpoint of further improving the insulation and durability of the battery packaging material. More preferably, it is about%. Further, the proportion of the ethylene unit contained in the modified polyethylene resin is preferably about 50 mol% to 100 mol% from the viewpoint of further improving the insulation and durability of the battery packaging material, and is preferably 80 mol% to More preferably, it is about 100 mol%. Each of the ethylene copolymer and the propylene copolymer may be a random copolymer or a block copolymer. Further, the ethylene copolymer and the propylene copolymer may each be crystalline or amorphous, and may be a copolymer or a mixture thereof. The polyolefin resin to be modified may be formed of one type of homopolymer or copolymer, or may be formed of two or more types of homopolymer or copolymer.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, and crotonic acid. Moreover, as an acid anhydride, the acid anhydride of the unsaturated carboxylic acid illustrated above is preferable, and maleic anhydride and itaconic anhydride are more preferable. The modified polypropylene resin may be one modified with one type of unsaturated carboxylic acid or acid anhydride thereof, or one modified with two or more types of unsaturated carboxylic acid or acid anhydrides thereof. May be.

  The ratio of the unsaturated carboxylic acid or its acid anhydride in the modified polyolefin resin is preferably about 0.1% by mass to 30% by mass, and preferably about 0.1% by mass to 20% by mass. More preferred. By setting it as such a range, the above-mentioned whitening can be suppressed effectively, improving the adhesiveness of the barrier layer 3 and the heat-fusible resin layer 4. FIG.

  The weight average molecular weight of the modified polyolefin resin is preferably about 6000 to 200000, and more preferably about 8000 to 150,000, respectively. By setting it as such a range, since the affinity of the adhesive resin layer 5 with respect to the barrier layer 3 and the heat-fusible resin layer 4 can be stabilized, the adhesion between the barrier layer 3 and the heat-fusible resin layer 4 can be maintained for a long time. Can be stabilized. Furthermore, the above-mentioned whitening can be effectively suppressed. The weight average molecular weight of the modified polyolefin resin is a value measured by gel permeation chromatography (GPC) measured under conditions using polystyrene as a standard sample.

  The melting point of the modified polyolefin resin is preferably about 60 ° C to 160 ° C, and more preferably about 70 ° C to 140 ° C. By setting it as such a range, since the affinity of the adhesive resin layer 5 with respect to the barrier layer 3 and the heat-fusible resin layer 4 can be stabilized, the adhesion between the barrier layer 3 and the heat-fusible resin layer 4 can be maintained for a long time. Can be stabilized. Furthermore, the above-mentioned whitening can be effectively suppressed. In the present invention, the melting point of the modified polyolefin resin refers to an endothermic peak temperature in differential scanning calorimetry.

  In the modified polyolefin resin, the method for modifying the polyolefin resin is not particularly limited, and for example, the polyolefin resin may be copolymerized with an unsaturated carboxylic acid or an acid anhydride thereof. Examples of such copolymerization include random copolymerization, block copolymerization, graft copolymerization (graft modification), and the like, and preferably graft copolymerization.

  While improving the curability of the thermosetting modified polyolefin resin to improve the adhesion between the barrier layer 3 and the heat-fusible resin layer 4, the above-mentioned whitening is further effectively suppressed and the resistance to electrolyte is improved. In view of the above, it is preferable that the thermosetting modified polyolefin resin further contains a curing agent in addition to the modified polyolefin resin.

  A hardening | curing agent will not be specifically limited if said modified polyolefin resin is hardened. Examples of the curing agent include an epoxy curing agent, a polyfunctional isocyanate curing agent, a carbodiimide curing agent, and an oxazoline curing agent.

  The epoxy curing agent is not particularly limited as long as it is a compound having at least one epoxy group. Examples of the epoxy curing agent include epoxy resins such as bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether.

  The polyfunctional isocyanate curing agent is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of the polyfunctional isocyanate-based curing agent include isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), those obtained by polymerizing or nurate, Examples thereof include mixtures and copolymers with other polymers.

  The carbodiimide curing agent is not particularly limited as long as it is a compound having at least one carbodiimide group (—N═C═N—). As the carbodiimide curing agent, a polycarbodiimide compound having at least two carbodiimide groups is preferable.

  The oxazoline-based curing agent is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the oxazoline-based curing agent include Epocros series manufactured by Nippon Shokubai Co., Ltd.

  From the viewpoint of enhancing the adhesion between the barrier layer 3 and the heat-fusible resin layer 4 by the adhesive resin layer 5, the curing agent may be composed of two or more kinds of compounds.

  The content of the curing agent in the thermosetting modified polyolefin resin is preferably in the range of 0.1% by mass to 50% by mass, more preferably in the range of 0.1% by mass to 30% by mass, More preferably, it is in the range of 0.1 mass% to 10 mass%.

  The thickness of the adhesive resin layer 5 is not particularly limited as long as it is suitable for the battery packaging material. However, the whitening described above is further effective while improving the adhesion between the barrier layer 3 and the heat-fusible resin layer 4. From the viewpoint of suppressing the resistance and improving the electrolytic solution resistance, it is preferably 30 μm or less, more preferably about 0.1 μm to 20 μm, and still more preferably about 0.5 μm to 5 μm.

  Further, the melting point of the adhesive resin layer 5 is preferably lower than the melting point of the heat-fusible resin layer 4 described later. Thereby, while improving the adhesion between the barrier layer 3 and the heat-fusible resin layer 4, the above-mentioned whitening can be more effectively suppressed and the electrolytic solution resistance can be improved. In the present invention, the melting point of the adhesive resin layer refers to an endothermic peak temperature in differential scanning calorimetry of a thermosetting modified polyolefin resin.

  Further, by adding an olefin rubber-like additive or a hydrocarbon wax to the adhesive resin layer 5, the adhesive resin layer 5 is made more flexible, and the adhesion between the barrier layer 3 and the heat-fusible resin layer 4. The above-mentioned whitening can be more effectively suppressed and the resistance to electrolytic solution can be improved while enhancing the properties. Examples of the olefinic rubber-like additive include Mitsui Chemicals' Tuffmer P, Tuffmer A, Tuffmer H, Tuffmer XM, Tuffmer BL, Tuffmer PN, and α-olefin copolymers such as Sumitomo Chemical's Tough Selenium. Examples of the hydrocarbon wax include paraffin.

[Heat-fusion resin layer 4]
In the battery packaging material of the present invention, the heat-fusible resin layer 4 corresponds to the innermost layer, and is a layer that heat-welds the heat-fusible resin layers together to seal the battery element when the battery is assembled.

  The resin component used for the heat-fusible resin layer 4 is not particularly limited as long as it can be heat-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 or polyolefin is preferable; carboxylic acid-modified polypropylene or polypropylene is more preferable, and ethylene-propylene copolymer is more preferable.

  The heat-fusible resin 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 heat-fusible resin 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.

  In the battery packaging material of the present invention, the heat-fusible resin layer 4 may contain a lubricant. The type of lubricant is not particularly limited, and examples thereof include those exemplified in the above item [Base Material Layer 1]. In the case where the heat-fusible resin layer 4 contains a lubricant, the content thereof may be appropriately selected, but preferably about 700 to 1200 ppm, more preferably about 800 to 1100 ppm. In the present invention, the content of the lubricant in the heat-fusible resin layer 4 is determined between the lubricant present inside the heat-fusible resin layer 4 and the lubricant present on the surface of the heat-fusible resin layer 4. Total amount.

  Moreover, although it can select suitably as thickness of the heat-fusible resin layer 4, about 10-100 micrometers, Preferably about 15-85 micrometers is mentioned.

4). Production method of battery packaging material The production method of the battery packaging material of the present invention is not particularly limited as long as the above-described laminate in which the respective layers having a predetermined composition are laminated is obtained. For example, the following method is exemplified. be able to.

  At least the base material layer 1, the barrier layer 3, the adhesive resin layer 5, and the heat-fusible resin layer 4 are laminated in this order to obtain a laminate. Specifically, first, the base material layer 1 and the barrier layer 3 are laminated. This lamination can be performed, for example, by a dry lamination method using the above-described adhesive component that forms the adhesive layer 2. In addition, as a method of laminating the base material layer 1 and the barrier layer 3, a method of extruding a resin for forming the base material layer 1 onto the barrier layer 3, or a method of depositing a metal on the base material layer 1. And a method of forming the barrier layer 3. Next, the thermosetting modified polyolefin resin used for forming the adhesive resin layer 5 is applied to the surface of the barrier layer 3 opposite to the base material layer 1 and dried. For the application of the thermosetting modified polyolefin resin, an application method such as an extrusion method, a gravure coating method, or a roll coating method can be employed. In addition, before laminating | stacking the base material layer 1, the barrier layer 3, and the adhesive resin layer 5, you may carry out the chemical conversion treatment of the metal which comprises the barrier layer 3 as mentioned above. Next, the heat-fusible resin layer 4 is laminated on the thermosetting modified polyolefin resin. This lamination can be performed by, for example, a dry lamination method.

  In order to improve the adhesiveness of each layer in the obtained laminate, an aging treatment or the like may be performed. The aging treatment can be performed, for example, by heating the laminate to a temperature environment of about 30 to 100 ° C. for 1 to 200 hours. Furthermore, in order to further improve the adhesion of each layer in the obtained laminate, the obtained laminate may be heated at a temperature equal to or higher than the melting point of the heat-fusible resin layer 4. The temperature at this time is preferably the melting point of the heat-fusible resin layer 4 + 5 ° C. or higher and the melting point + 100 ° C. or lower, more preferably the melting point + 10 ° C. or higher and the melting point + 80 ° C. or lower. Only one or both of the aging treatment and the heat treatment at a temperature equal to or higher than the melting point of the heat-fusible resin layer 4 may be performed. In the present invention, the melting point of the heat-fusible resin layer refers to the endothermic peak temperature in differential scanning calorimetry of the resin component constituting the heat-fusible resin layer. Heating in the aging treatment and heating above the melting point of the heat-fusible resin layer 4 can be performed by a method such as a hot roll contact method, a hot air method, a near or far infrared method, respectively.

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

5. Application of Battery Packaging Material The battery packaging material of the present invention is used as a package for sealing and housing battery elements such as a positive electrode, a negative electrode, and an electrolyte. That is, the battery packaging material of the present invention can be deformed in accordance with the shape of the battery element to form a packaging body that accommodates the battery element.

  Specifically, at least a battery element including a positive electrode, a negative electrode, and an electrolyte is provided with a flange portion (heat fusion) on the periphery of the battery element with a metal terminal connected to each of the positive electrode and the negative electrode protruding outward. A region where the adhesive resin layers are in contact with each other is formed so as to be covered with the battery packaging material of the present invention. Next, the battery sealed with the battery packaging material (packaging body) of the present invention is provided by heat-sealing and sealing the heat-fusible resin layers of the flange portion. When a battery element is accommodated using the package of the present invention, the heat-fusible resin layer 4 of the battery packaging material of the present invention is used so that it is on the inner side (surface in contact with the battery element).

  The battery packaging material of the present invention can be used for both primary batteries and secondary batteries, but is particularly suitable for use in secondary batteries. The type of the 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 live battery, a nickel / hydrogen live battery, a nickel / cadmium live battery Nickel / iron livestock batteries, nickel / zinc livestock batteries, silver oxide / zinc livestock batteries, metal-air batteries, multivalent 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.

  As described above, in the battery packaging material for high molding (for example, for high molding stretched to a maximum stretching ratio of 120% or more) used for large batteries for vehicles, the heat-fusible resin layer side The modified polyolefin resin located in the whitening has the problem that the electrolytic solution resistance is liable to decrease, but according to the battery packaging material of the present invention, even when stretched at a high stretch ratio And the fall of electrolyte solution resistance is suppressed effectively. For this reason, the battery packaging material of this invention can be used especially suitably as a battery packaging material for high molding used for a vehicle battery or the like.

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

<Example 1>
As the barrier layer, one obtained by chemical conversion treatment on both surfaces of an aluminum foil (thickness 35 μm) made of soft aluminum ((JIS H4160 A8021H-O)) was used. A treatment liquid composed of phosphoric acid was applied to both surfaces of the barrier layer by a roll coating method to form a film, and baked for 20 seconds under the condition that the film temperature was 180 ° C. or higher. In order to form an adhesive layer on one surface of the aluminum foil, an adhesive using a polyester-polyol resin as a main agent and a TMP adduct type TDI curing agent as a curing agent is set to 4 μm in thickness. Next, from this adhesive, a biaxially stretched nylon film 15 μm serving as a base material layer was dry laminated. Bonded by chromatography method, a base layer, an adhesive layer, and to obtain a laminate barrier layer are laminated.

  Next, in order to form an adhesive resin layer on the other surface of the aluminum foil of the laminate, a modified polyolefin resin (maleic anhydride-modified ethylene-propylene copolymer, weight average molecular weight 100,000, melting point 100 ° C., polypropylene main A thermosetting modified polyolefin resin obtained by mixing an ethylene content of 2.1 mol% in the skeleton and a maleic anhydride modification degree of 3.0% by mass) and an epoxy curing agent is applied to a thickness of 2 μm. And dried. In addition, content of the hardening | curing agent was 5 mass% with respect to the total solid content weight after drying.

  Next, an unstretched polypropylene film (ethylene-propylene random copolymer type, thickness 30 μm, melting point 140 ° C.) that forms a heat-fusible resin layer is laminated on the dried thermosetting modified polyolefin resin. Each layer was bonded by a dry laminating method to obtain a laminate. Furthermore, the obtained laminate was aged in a temperature environment of 80 ° C. for 24 hours, and finally heated at 190 ° C. for 2 minutes, whereby a base material layer, an adhesive layer, a barrier layer, an adhesive resin layer, a heat-fusible resin layer A battery packaging material laminated in this order was obtained.

<Example 2>
As Example 1, except that the aluminum foil (thickness 30 μm) made of soft aluminum ((JIS H4160 A8021H-O) was used as the barrier layer and the thickness of the heat-fusible resin layer was 25 μm. Thus, a battery packaging material was obtained in which a base material layer, an adhesive layer, a barrier layer, an adhesive resin layer, and a heat-fusible resin layer were laminated in this order.

<Example 3>
The base material layer, the adhesive layer, the barrier layer, the adhesive resin layer, and the heat fusion property are the same as in Example 1 except that the addition amount of the curing agent is 30% by mass with respect to the total solid weight after drying. An electrical packaging material having a resin layer laminated in this order was obtained.

<Example 4>
As an adhesive for forming an adhesive resin layer on the other surface of the aluminum foil of the laminate in which the base material layer, the adhesive layer, and the barrier layer are laminated instead of the adhesive resin layer formed in Example 1. , Modified polyolefin resin (maleic anhydride modified ethylene-propylene copolymer, weight average molecular weight 100,000, melting point 100 ° C., ethylene content in polypropylene main skeleton 2.1 mol%, maleic anhydride modified degree 3.0 mass%) Example 1 except that a thermosetting modified polyolefin resin obtained by mixing styrene and tolylene diisocyanate (TDI) curing agent was applied to a thickness of 2 μm and dried to form an adhesive resin layer. In the same manner as above, an electrical packaging material in which a base material layer, an adhesive layer, a barrier layer, an adhesive resin layer, and a heat-fusible resin layer were laminated in this order was obtained.

<Example 5>
As an adhesive for forming an adhesive resin layer on the other surface of the aluminum foil of the laminate in which the base material layer, the adhesive layer, and the barrier layer are laminated instead of the adhesive resin layer formed in Example 1. , Modified polyolefin resin (maleic anhydride modified ethylene-propylene copolymer, weight average molecular weight 100,000, melting point 100 ° C., ethylene content in polypropylene main skeleton 2.1 mol%, maleic anhydride modified degree 3.0 mass%) And a thermosetting modified polyolefin resin obtained by mixing a diphenylmethane diisocyanate (MDI) curing agent with a thickness of 2 μm and dried to form an adhesive resin layer. The thickness of the resulting biaxially stretched nylon film was 25 μm, and the barrier layer was soft aluminum ((JIS H4160 A8021H-O) or Substrate layer, adhesive layer, barrier layer, adhesive resin in the same manner as in Example 1, except that the aluminum foil (thickness: 40 μm) is used and the thickness of the heat-fusible resin layer is 80 μm. An electrical packaging material in which a layer and a heat-fusible resin layer were laminated in this order was obtained.

<Comparative Example 1>
In the same manner as in Example 1, a laminate in which a base material layer, an adhesive layer, and a barrier layer were laminated was obtained. Next, a modified polypropylene resin (maleic anhydride-modified ethylene-propylene copolymer, weight average molecular weight 100,000, melting point 100 ° C., ethylene content in the polypropylene main skeleton is formed on the barrier layer to form an adhesive resin layer. 2.1 mol%, maleic anhydride modification degree 3.0 mass%, thickness 20 μm) was extruded and laminated with an unstretched polypropylene film by an extrusion laminating machine. Furthermore, the obtained laminate was aged in a temperature environment of 80 ° C. for 24 hours, and finally heated at 190 ° C. for 2 minutes, whereby a base material layer, an adhesive layer, a barrier layer, an adhesive resin layer, a heat-fusible resin layer A battery packaging material laminated in this order was obtained.

<Whitening evaluation>
Each battery packaging material obtained above was cut into 100 mm (MD direction, vertical direction) × 15 mm (TD direction, horizontal direction) to obtain test pieces. Next, the obtained test piece was stretched by 150% using a tensile tester (trade name AGS-50D manufactured by Shimadzu Corporation) at a distance between grips of 50 mm and a speed of 50 mm / min. Next, the brightness L ^* value was measured from the heat-fusible resin layer side of the test piece before and after stretching using a microspectrometer (USPM-RUIII manufactured by Olympus). Table 1 shows the brightness difference ΔL values of the test pieces before and after stretching.

<Evaluation of electrolyte resistance>
Each battery packaging material stretched in the above whitening evaluation was put into a glass bottle, and the electrolyte was injected until the various battery packaging materials were completely immersed. The electrolytic solution was obtained by mixing lithium hexafluorophosphate with a solution mixed at a volume ratio of ethylene carbonate: diethyl carbonate: dimethyl carbonate = 1: 1: 1. Next, the glass bottle was sealed and left in a constant temperature layer at 85 ° C. for 24 hours.

Next, the glass bottle was taken out from the thermostatic layer, opened, and the electrolytic solution was taken out. Next, the battery packaging material is peeled off between the heat-fusible resin layer / barrier layer and pulled at a speed of 50 mm / min using a tensile tester (trade name AGS-50D manufactured by Shimadzu Corporation). The peel strength (N / 15 mm) was measured (tensile strength after the test). Electrolytic solution resistance was evaluated according to the following criteria. The results are shown in Table 1.
○: Tensile strength difference before and after the test is less than 4.0 N / 15 mm Δ: Tensile strength difference before and after the test is 4.0 to 5.0 N / 15 mm ×: Tensile strength difference before and after the test is 5.0 N / Over 15mm

<Measurement of hardness of adhesive resin layer>
As a hardness measurement device, a nanoindenter (“TriboIndenter TI950” manufactured by HYSITRON (Heiditron) Co., Ltd.) was used. In an environment with a humidity of 50% and 23 ° C., the indenter is applied to the surface of the adhesive resin layer of the battery packaging material (the surface where the adhesive resin layer is exposed and perpendicular to the stacking direction of the layers) for 10 seconds. The indenter was pushed into the adhesive resin layer from the surface to a load of 40 μN, held in that state for 5 seconds, and then unloaded for 10 seconds.Maximum load P _max (μN) and indentation at maximum depth Using the area A (nm ² ), the indentation hardness (MPa) was calculated by P _max / A, and the measurement results are shown in Table 1. The surface into which the indenter is pressed is The cross section of the adhesive resin layer obtained by cutting in the thickness direction so as to pass through the central portion of the battery packaging material was exposed using a commercially available rotary microtome or the like.

  In the battery packaging materials of Examples 1 and 2 in which the adhesive resin layer is a cured product of a thermosetting modified polyolefin resin and the value of the brightness difference ΔL is 35 or less, the whitening of the heat-fusible resin layer is performed. Was less likely to occur and the electrolyte solution resistance was excellent. On the other hand, in the battery packaging material of Comparative Example 1 in which the adhesive resin layer is formed of a modified polypropylene resin and the value of the brightness difference ΔL exceeds 35, whitening of the heat-fusible resin layer is likely to occur. The electrolyte solution resistance was poor.

DESCRIPTION OF SYMBOLS 1 ... Base material layer 2 ... Adhesive layer 3 ... Barrier layer 4 ... Heat-fusion resin layer 5 ... Adhesive resin layer

Claims (10)

At least comprising a laminate comprising a base material layer, a barrier layer, an adhesive resin layer, and a heat-fusible resin layer in order from the outside,
The adhesive resin layer is made of a cured product of a thermosetting modified polyolefin resin,
When the laminate is stretched in a direction perpendicular to the thickness direction at a stretch ratio of 150%, the value of the brightness difference ΔL measured from the heat-fusible resin layer side of the laminate before and after the stretching is 35 or less. A battery packaging material.   The battery packaging material according to claim 1, wherein the adhesive resin layer has a thickness of 30 μm or less.   The battery packaging material according to claim 1 or 2, wherein the thermosetting modified polyolefin resin includes a modified polyolefin resin modified with an unsaturated carboxylic acid or an acid anhydride thereof.   The battery packaging material according to claim 1, wherein the thermosetting modified polyolefin resin is thermosetting modified polypropylene.   The battery packaging material according to claim 1, wherein the thermosetting acid-modified polyolefin resin further contains a curing agent.   The battery packaging material according to claim 1, wherein a melting point of the adhesive resin layer is lower than a melting point of the heat-fusible resin layer.   The battery packaging material according to any one of claims 1 to 6, wherein the barrier layer is formed of an aluminum foil.   The battery packaging material according to any one of claims 1 to 7, wherein the battery packaging material is for high molding stretched to a maximum stretching ratio of 120% or more.   The battery packaging material according to claim 1, wherein the adhesive resin layer has a hardness measured by a nanoindentation method of 10 MPa or more and 300 MPa or less.   The battery in which the battery element provided with the positive electrode, the negative electrode, and the electrolyte is accommodated in the packaging body formed with the packaging material for batteries in any one of Claims 1-9.