JP2015207561A - Resin composition for sealant layer of battery packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition by which when the resin composition is used for a sealant layer of a battery packaging material, the occurrence of a crack in bending a thermally sealed portion of the battery packaging material can be suppressed, and a large insulating property can be imparted to the battery packaging material.SOLUTION: A resin composition for a sealant layer of a battery packaging material comprises a polyolefin-based resin, of which the isotactic pentad fraction (mm) is 99% or less.

Description

  The present invention relates to a resin composition capable of imparting high insulation to a battery packaging material when used in a sealant layer of the battery packaging material.

  Conventionally, various types of batteries have been developed. In any battery, a packaging material is an indispensable member for sealing battery elements such as electrodes and electrolytes. Conventionally, metal packaging materials have been widely used as battery packaging, but in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., batteries are required to have various shapes. At the same time, there is a demand for reduction in thickness and weight. However, metal battery packaging materials that have been widely used in the past have the disadvantages that it is difficult to follow the diversification of shapes and that there is a limit to weight reduction.

  Therefore, a film-like laminate in which a base material layer / adhesive layer / metal layer / sealant layer are sequentially laminated is proposed as a battery packaging material that can be easily processed into various shapes and can be made thinner and lighter. (For example, refer to Patent Document 1). Such a film-shaped battery packaging material is formed so that the battery element can be sealed by causing the sealant layers to face each other and heat-sealing the peripheral portion by heat sealing.

  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.

  In recent years, with demands for battery thickness reduction and weight reduction, thinner battery packaging materials have been demanded, and the sealant layer is also required to be made thinner. However, when the thickness of the sealant layer is reduced, the insulating property of the battery packaging material tends to be lowered. In particular, when the electronic device is sealed with the battery packaging material in the battery manufacturing process, the battery packaging material may be heat-sealed, and then the heat-sealed portion may be bent inward. In such a case, there is a problem that the insulation is particularly likely to be deteriorated due to cracks occurring in the heat seal portion of the sealant layer or in the vicinity thereof.

JP 2008-287971 A

  Under such circumstances, when the present invention is used for a sealant layer of a battery packaging material, it suppresses the occurrence of cracks when the heat seal portion of the battery packaging material is bent, and is high in battery packaging material. The main object is to provide a resin composition capable of imparting insulating properties.

  The present inventor conducted intensive studies to solve the above-mentioned problems. As a result, a resin composition containing a polyolefin resin having an isotactic fraction (mm) of 99% or less is used as a sealant layer of a battery packaging material. It has been found that, when used, the generation of cracks when the heat seal portion of the battery packaging material is bent can be suppressed, and high insulation can be imparted to the battery packaging material. The present invention has been completed by further studies based on such knowledge.

That is, this invention provides the invention of the aspect hung up below.
Item 1. A resin composition for a sealant layer of a battery packaging material, comprising a polyolefin resin having an isotactic fraction (mm) of 99% or less.
Item 2. Item 2. The resin composition according to Item 1, wherein the polyolefin resin has an ethylene unit content of 0.1 to 10 mol%.
Item 3. Item 3. The resin composition according to Item 1 or 2, wherein the polyolefin resin has an amount of a component soluble in n-decane at 80 ° C of 0.1 to 15% by mass.
Item 4. Item 4. The resin composition according to any one of Items 1 to 3, wherein the polyolefin-based resin contains at least propylene as a constituent monomer.
Item 5. A battery packaging material comprising a laminate having at least a base material layer, a metal layer, and a sealant layer in this order,
The battery packaging material in which the sealant layer includes a layer formed of the resin composition according to any one of Items 1 to 4.
Item 6. Item 6. The battery packaging material according to Item 5, wherein the layer formed of the resin composition has a thickness of 1 to 20 µm.
Item 7. Item 7. The battery packaging material according to Item 5 or 6, wherein the sealant layer has a thickness of 40 µm or less.
Item 8. Item 8. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is sealed with the battery packaging material according to any one of Items 5 to 7.

  According to the present invention, when used in a sealant layer of a battery packaging material, generation of cracks when the heat seal portion of the battery packaging material is bent is suppressed, and high insulation is imparted to the battery packaging material. The resin composition which can be provided can be provided. Moreover, according to this invention, the packaging material for batteries which used the said resin composition for the sealant layer, and a battery can be provided.

It is a schematic sectional drawing of the packaging material for batteries of this invention. It is a schematic sectional drawing of the packaging material for batteries of this invention.

  The resin composition of the present invention is characterized by containing a polyolefin resin having an isotactic fraction (mm) of 99% or less. Hereinafter, the resin composition of the present invention, the battery packaging material using the resin composition for the sealant layer, and the battery will be described in detail.

1. Resin composition The resin composition of the present invention is a resin composition used for, for example, a sealant layer of a battery packaging material as described later, and has an isotactic fraction (mm) of 99% or less. including. The isotactic fraction (mm) of the polyolefin resin is a value obtained by measurement of ¹³ C nuclear magnetic resonance spectrum.

  As described above, in the manufacturing process of the battery, when the electronic element is sealed with the battery packaging material, the heat seal portion may be bent inward to be molded. At this time, cracks occur in the heat seal portion of the sealant layer or in the vicinity thereof, and the insulation of the battery packaging material tends to be lowered. In particular, when the heat seal part is formed thin (for example, 40 μm or less), there is a problem that the deterioration of the insulation becomes remarkable. On the other hand, by using the resin composition of the present invention for the sealant layer of the battery packaging material, even when the sealant layer is thinly formed, it is possible to effectively reduce the insulation when the heat seal part is bent. Can be suppressed. Although the details of the mechanism by which the insulating property is enhanced even when the thickness of the sealant layer is reduced by using the resin composition of the present invention for the sealant layer is not clear, for example, the following may be considered. it can. That is, the polyolefin resin having an isotactic fraction (mm) of 99% or less contained in the resin composition of the present invention has low stereoregularity of the polymer chain and low crystallinity. For this reason, when the layer formed of the resin composition of the present invention is included in the sealant layer, the sealant layer easily follows external stress applied when the heat seal portion of the battery packaging material is bent. It is considered that the occurrence of cracks is suppressed, and as a result, the insulation is enhanced.

  The isotactic fraction (mm) of the polyolefin resin is not particularly limited as long as it is 99% or less. However, even when the sealant layer is thinly formed, from the viewpoint of imparting high insulation to the battery packaging material. Is preferably 90% or more, more preferably 93% or more, and still more preferably 95% or more.

  The polyolefin resin contained in the resin composition of the present invention is not particularly limited as long as it satisfies the above isotactic fraction. The polyolefin resin may be composed of one type of resin, or may be composed of two or more types of resins. The polyolefin resin can be composed of, for example, polyolefin. The polyolefin is not particularly limited as long as it has the above-described physical properties. For example, polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene; homopolypropylene, polypropylene block copolymer ( Examples thereof include crystalline or amorphous polypropylene such as propylene and ethylene block copolymers) and polypropylene random copolymers (for example, propylene and ethylene random copolymers); ethylene-butene-propylene terpolymers, and the like. Among these polyolefins, in view of heat resistance, a polyolefin having at least propylene as a constituent monomer is preferable, and a propylene-ethylene random copolymer, a propylene-ethylene-butene terpolymer, and a propylene homopolymer are more preferable. Particularly preferred are propylene-ethylene random copolymers. These polyolefins may be used individually by 1 type, and may be used in combination of 2 or more type.

  As a resin constituting the polyolefin-based resin, examples of the resin other than polyolefin include acid-modified polyolefin. The acid-modified polyolefin is a polymer modified by graft polymerization of polyolefin with an unsaturated carboxylic acid. Specific examples of the acid-modified polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; homopolypropylene, block copolymer of polypropylene (for example, block copolymer of propylene and ethylene) ), A random or amorphous polypropylene copolymer (for example, a random copolymer of propylene and ethylene), and a terpolymer of ethylene-butene-propylene. Among these polyolefins, from the viewpoint of heat resistance, polyolefins having at least propylene as a constituent monomer are preferable, and ethylene-butene-propylene terpolymers and propylene-ethylene random copolymers are more preferable. Examples of the unsaturated carboxylic acid used for modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like. Among these unsaturated carboxylic acids, maleic acid and maleic anhydride are preferable. These acid-modified polyolefins may be used individually by 1 type, and may be used in combination of 2 or more type.

From the viewpoint of further improving the insulation when the heat seal part of the battery packaging material is bent, the polyolefin resin preferably has an ethylene unit content of about 0.1 to 10 mol%, and 1 to 8 mol. % Is more preferable, and about 1 to 6 mol% is more preferable. When the content of the ethylene unit in the polyolefin resin is in such a range, it is considered that the mobility of the molecular chain constituting the polyolefin resin is increased and the flexibility is enhanced. For this reason, the sealant layer more easily follows external stress applied when the heat sealing part of the battery packaging material is bent, and the generation of cracks is suppressed, resulting in higher insulation. it is conceivable that. In the present invention, the content of ethylene units in the polyolefin-based resin is a value obtained by measurement of ¹³ C nuclear magnetic resonance spectrum.

  Further, from the viewpoint of further improving the insulation when the heat seal part of the battery packaging material is bent, the polyolefin resin has an amount of components soluble in n-decane of 0.1 to 15% by mass at 80 ° C. It is preferable that it is 1-12 mass%, It is more preferable that it is 1-10 mass%. Since polymers with lower stereoregularity tend to elute into n-decane, the amount of components soluble in n-decane at 80 ° C. of the polyolefin resin is in such a range. It is considered that the mobility of the constituent molecular chains is increased and the flexibility is increased. For this reason, the sealant layer more easily follows external stress applied when the heat sealing part of the battery packaging material is bent, and the generation of cracks is suppressed, resulting in higher insulation. it is conceivable that. In the polyolefin resin, the amount of the component soluble in n-decane is the amount of the polyolefin resin that was not dissolved by stirring 100 parts by mass of the polyolefin resin in 1000 parts by mass of n-decane at 80 ° C. It is a value calculated from

  The physical properties such as the isotactic fraction of the polyolefin resin, the content of ethylene units, and the amount of components soluble in n-decane at 80 ° C. are determined by the molecular weight of the polyolefin resin, the type and ratio of constituent monomers, and the like. In the polyolefin resin, the molecular weight, the type and ratio of constituent monomers, etc. are set so that at least the isotactic fraction (mm) has physical properties of 99% or less.

2. Battery Packaging Material The battery packaging material of the present invention comprises a laminate having at least a base material layer 1, a metal layer 3, and a sealant layer 4 in this order. As shown in FIG. 1, the battery packaging material of the present invention may have an adhesive layer 2 between a base material layer 1 and a metal layer 3. When the battery packaging material of the present invention is used in a battery, the base material layer 1 is the outermost layer and the sealant layer 4 is the innermost layer (battery element side). When assembling the battery, the sealant layers 4 located on the periphery of the battery element are brought into contact with each other and thermally welded to seal the battery element and seal the battery element. Moreover, the battery packaging material of the present invention may have an adhesive layer 5 between the metal layer 3 and the sealant layer 4 as shown in FIG.

3. Composition of each layer forming base material for battery [base material layer 1]
In the battery packaging material of the present invention, the base material layer 1 is a layer forming the outermost layer. The material for forming the base material layer 1 is not particularly limited as long as it has insulating properties. Examples of the material for forming the base material layer 1 include 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 copolymers of nylon 6 and nylon 6,6; terephthalic acid and / or Nylon 6I, Nylon 6T, Nylon 6IT, Nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid) and the like, which include a structural unit derived from isophthalic acid, Aromatic polyamides such as silylene adipamide (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); and lactam components and isocyanate components such as 4,4′-diphenylmethane-diisocyanate. Polymerized polyamide, co-weight Polyester amide copolymer and polyether ester amide copolymer is a copolymer of polyamide and 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 raw material on the metal 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 is 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. Further, the bonding 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 curing type such as UV and EB, 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 slip agent, 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. As a matting agent, specifically, talc, silica, graphite, kaolin, montmorilloid, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, oxidation Aluminum, 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. 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 slip agent can be formed by depositing the slip agent on the surface of the base material layer 1 by bleeding out to form a thin layer, or by laminating the slip agent on the base material layer 1. The slip agent is not particularly limited. For example, fatty acid amide, 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 slip agents 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.

[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 metal layer 3.

  The adhesive layer 2 is formed of an adhesive capable of adhering the base material layer 1 and the metal layer 3. The adhesive used for forming the adhesive layer 2 may be a two-component curable adhesive or a one-component curable adhesive. Furthermore, the adhesive mechanism of the adhesive used for forming the adhesive layer 2 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a hot pressure type, and the like.

  Specific examples of the 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 lamination strength between the base material layer 1 and the metal 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 material layer 1 and the metal layer 3, the adhesive component disposed on the base material layer 1 side is used as the base material layer 1. It is preferable to select a resin having excellent adhesion to the metal layer 3 and to select an adhesive component having excellent adhesion to the metal layer 3 as the adhesive component disposed on the metal layer 3 side. When the adhesive layer 2 is multilayered with different adhesive components, specifically, the adhesive component disposed on the metal 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 3-25 micrometers is mentioned.

[Metal layer 3]
In the battery packaging material of the present invention, the metal layer 3 is a layer that functions as a barrier layer for preventing the penetration of water vapor, oxygen, light, etc. into the battery, in addition to improving the strength of the packaging material. Specific examples of the metal forming the metal layer 3 include metal foils such as aluminum, stainless steel, and titanium. Among these, aluminum is preferably used. In order to prevent wrinkles and pinholes during the production of the packaging material, soft aluminum such as annealed aluminum (JIS A8021P-O) or (JIS A8079P-O) is used as the metal layer 3 in the present invention. Is preferred.

  About thickness of the metal layer 3, 10-200 micrometers is preferable, for example, Preferably it is 20-100 micrometers.

  Further, the metal layer 3 is preferably subjected to chemical conversion treatment on at least one surface, preferably at least the surface on the sealant layer 4 side, and more preferably both surfaces, for the purpose of stabilizing adhesion, preventing dissolution and corrosion, and the like. . Here, the chemical conversion treatment is a treatment for forming an acid-resistant film on the surface of the metal layer 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 general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ¹ and R ² are the same or different and represent a hydroxyl group, an alkyl group, or a hydroxyalkyl group. In the general formulas (1) to (4), examples of the alkyl group represented by X, R ¹ and R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, C1-C4 linear or branched alkyl groups, such as a tert- butyl group, are mentioned. Examples of the hydroxyalkyl group represented by X, R ¹ and R ² include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, 3- A linear or branched chain having 1 to 4 carbon atoms substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group An alkyl group is mentioned. be able to. In the general formulas (1) to (4), X is preferably any one of a hydrogen atom, a hydroxyl group, and a droxyalkyl group. The number average molecular weight of the aminated phenol polymer composed of the repeating units represented by the general formulas (1) to (4) is, for example, about 500 to about 1,000,000, preferably about 1000 to about 20,000.

  In addition, as a chemical conversion treatment method for imparting corrosion resistance to the metal layer 3, a metal oxide such as aluminum oxide, titanium oxide, cerium oxide, tin oxide, or barium sulfate fine particles dispersed in phosphoric acid is coated. A method of forming a corrosion-resistant treatment layer on the surface of the metal layer 3 by performing a baking treatment at 150 ° C. or higher can be mentioned. 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 metal 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. The chromic acid compound is about 0.5 to about 50 mg, preferably about 1.0 to about 40 mg in terms of chromium, and the phosphorus compound is about 0.5 to about 50 mg in terms of phosphorus per 1 m ² of the surface of the metal layer 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 metal 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 metal layer 3 Is performed by heating so as to be about 70 to 200 ° C. In addition, 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 dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like in advance. By performing the degreasing treatment in this way, it becomes possible to more efficiently perform the chemical conversion treatment on the surface of the metal layer 3.

[Sealant layer 4]
In the battery packaging material of the present invention, the sealant layer 4 corresponds to the innermost layer, and the sealant layers 4 are heat-welded to each other to seal the battery element when the battery is assembled. The sealant layer 4 may be composed of one layer formed of the resin composition of the present invention, or may be composed of a plurality of layers formed of the resin composition. In addition to the layer formed from the resin composition of the present invention, the sealant layer 4 may further include one or more other layers not formed from the resin composition of the present invention. For example, in the packaging material for a battery of the present invention, the sealant layer 4 is formed by a first sealant layer located on the metal layer 3 side and a second sealant layer located in the innermost layer of the sealant layers 4. The sealant layer may correspond to a layer formed of the resin composition of the present invention, and the first sealant layer may have a layer configuration corresponding to other layers not formed of the resin composition of the present invention. The layer structure may be reversed.

  In addition, the layer formed of the resin composition of the present invention may contain a polyolefin resin having an isotactic fraction exceeding 99%. Moreover, the layer formed with the resin composition of this invention may contain resin other than polyolefin resin.

  When the layer formed of the resin composition of the present invention contains a polyolefin resin having an isotactic fraction exceeding 99% or a resin other than a polyolefin resin, the isotactic fraction in the layer is 99%. The content of the following polyolefin resin is not particularly limited as long as the effect of the present invention is not hindered, but preferably 50% by mass or more. The layer formed of the resin composition of the present invention may be formed of substantially only a polyolefin resin having an isotactic fraction of 99% or less.

In the sealant layer 4, the melting point T _m1 of the layer formed of the resin composition of the present invention is not particularly limited, but from the viewpoint of further improving the insulation when the heat seal part of the battery packaging material is bent. Preferably, it is 100-160 degreeC, More preferably, it is 105-150 degreeC, More preferably, it is 110-140 degreeC. Further, the softening point T _s1 of the layer formed of the resin composition of the present invention is not particularly limited, but from the same viewpoint as the melting point, it is preferably 60 to 150 ° C, more preferably 65 to 140 ° C, Preferably 70-120 degreeC is mentioned.

Here, the melting point T _m1 is measured by the DSC method according to JIS K6921-2 (ISO 1873-2.2: 95), which is the melting point of the resin component constituting the layer formed of the resin composition of the present invention. Value. In addition, when this layer is formed of a blend resin containing a plurality of resin components, the melting point T _m1 of the blend resin conforms to JIS K6921-2 (ISO 1873-2.2: 95) and the DSC method. To calculate the ratio of the peak area of the melting point corresponding to each resin component, with the total peak area being 1, and multiplying the ratio of the melting point corresponding to each resin component to the ratio of the peak area (melting point × area ratio) Furthermore, it is obtained by adding the value (melting point × area ratio) calculated for each melting point.

Moreover, said softening point _Ts1 is a value measured by Vicat softening temperature test method JISK7206. When this layer is formed of a blend resin containing a plurality of resin components, the softening point T _s1 is obtained by the sum of the softening point of the constituent components of the blend resin × the blending fraction.

  From the viewpoint of forming the sealant layer 4 as thin as possible while maintaining the high insulation of the battery packaging material, the thickness of the layer formed from the resin composition of the present invention is, for example, 1 to 20 μm, preferably 3 -18 micrometers, More preferably, 5-15 micrometers is mentioned.

  On the other hand, the resin which is not formed by the resin composition of the present invention and forms other layers arbitrarily provided is not particularly limited as long as the effects of the present invention are exhibited. For example, carboxylic acid-modified polyolefin And acid-modified polyolefin such as carboxylic acid-modified cyclic polyolefin, polyolefin, and cyclic polyolefin.

  Specific examples of polyolefins include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; homopolypropylene, polypropylene block copolymers (for example, block copolymers of propylene and ethylene), polypropylene Crystalline or amorphous polypropylene such as random copolymers (eg, random copolymers of propylene and ethylene); ethylene-butene-propylene terpolymers, and the like. Among these polyolefins, polyethylene and polypropylene are preferable.

  Cyclic polyolefin is a copolymer of olefin and cyclic monomer. Examples of the olefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of the cyclic monomer include cyclic alkenes such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, and the like. Among these polyolefins, a cyclic alkene is preferable, and norbornene is more preferable.

  The carboxylic acid-modified polyolefin is a polymer obtained by modifying the above polyolefin with a 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 a copolymer obtained by copolymerizing a part of the monomer constituting the cyclic polyolefin in place of the α, β-unsaturated carboxylic acid or its acid anhydride, or α, β with respect to the cyclic polyolefin. -A polymer obtained by block copolymerization or graft copolymerization of an unsaturated carboxylic acid or its acid anhydride. The cyclic polyolefin to be modified with carboxylic acid can be the same as the above cyclic polyolefin. The carboxylic acid used for modification can be the same as that used for modification of the acid-modified cycloolefin copolymer.

  Among these resin components, acid-modified polyolefins, crystalline or amorphous polyolefins, cyclic polyolefins, and blended polymers thereof; more preferably polyethylene, polypropylene, copolymers of ethylene and norbornene, and among them 2 or more types of blend polymers.

  The other layer may be formed from only one type of resin component, or may be formed from a blend polymer that combines two or more types of resin components.

In the sealant layer 4, the melting point T _m2 of the other layers is not particularly limited, but is preferably 100 to 160 ° C. from the viewpoint of further improving the insulation when the heat seal part of the battery packaging material is bent. More preferably, it is 105-150 degreeC, More preferably, 110-140 degreeC is mentioned. In addition, the softening point T _s2 of the other layer is not particularly limited, but from the same viewpoint as the melting point, it is preferably 60 to 150 ° C, more preferably 65 to 140 ° C, and further preferably 75 to 120 ° C. It is done.

The calculation method of the melting point T _m2 and softening point softening point T _s2 of the other layers is the same as the case of the melting point T _m1 and softening point T _s1 of the layer formed of the resin composition of the present invention.

(Total thickness of sealant layer 4)
The total thickness of the sealant layer 4 is preferably 40 μm or less, more preferably 20 to 40 μm from the viewpoint of forming the sealant layer 4 as thin as possible while maintaining high insulation of the battery packaging material.

[Adhesive layer 5]
In the battery packaging material, an adhesive layer 5 may be further provided between the metal layer 3 and the sealant layer 4 for the purpose of firmly bonding the metal layer 3 and the sealant layer 4.

  The adhesive layer 5 is formed of an adhesive component capable of bonding the metal layer 3 and a sealant layer 4 described later. The adhesive used for forming the adhesive layer 5 may be a two-component curable adhesive or a one-component curable adhesive. Moreover, it does not specifically limit about the adhesion | attachment mechanism of the adhesive agent component used for formation of the contact bonding layer 5, For example, a chemical reaction type | mold, a solvent volatilization type | mold, a hot-melt type, a hot-pressure type etc. are mentioned.

  Specific examples of the adhesive component that can be used to form the adhesive layer 5 include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, copolymer polyester, and other polyester resins; polyethers Polyurethane adhesives; epoxy resins; phenol resin resins; polyamide resins such as nylon 6, nylon 66, nylon 12, copolymer polyamides; polyolefins such as polyolefins, carboxylic acid modified polyolefins, metal modified polyolefins 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; and silicone resins. These adhesive components may be used alone or in combination of two or more.

  Although it does not restrict | limit especially as thickness of the contact bonding layer 5, Preferably it is 0.01 micrometer or more, More preferably, 0.05-20 micrometers is mentioned.

3. Method for Producing Battery Packaging Material The method for producing the battery packaging material of the present invention is not particularly limited as long as a laminate in which layers having a predetermined composition are laminated is obtained. For example, the following method is exemplified. .

  First, a laminate in which the base material layer 1, the adhesive layer 2, and the metal layer 3 are laminated in order (hereinafter also referred to as “laminate A”) is formed. Specifically, the laminate A is formed by using a thermal laminating method, a sand laminating method, using an adhesive that forms the adhesive layer 2 on the base material 1 and the metal layer 3 whose surface is subjected to a chemical conversion treatment if necessary. It is performed by laminating by a method or a combination thereof.

  The laminate A is formed by the thermal laminating method. For example, a multilayer film in which the base material layer 1 and the adhesive layer 2 are laminated is prepared in advance, and the metal layer 3 is superimposed on the adhesive layer 2 and heated with a heating roll. It can be performed by thermocompression bonding with the adhesive layer 2 sandwiched between the layer 1 and the metal layer 3. The laminate A is formed by the thermal laminating method in which a multilayer film in which the metal layer 3 and the adhesive layer 2 are laminated is prepared in advance, and the base material layer 1 is superposed on the heated metal layer 3 and the adhesive layer 2. It may be performed by thermocompression bonding while sandwiching the adhesive layer 2 between the base material layer 1 and the metal layer 3. In addition, the base material layer 1 and the metal layer 3 may be directly laminated without using the adhesive layer 2.

  In addition, the multilayer film in which the base material layer 1 and the adhesive layer 2 prepared in advance in the thermal laminating method are laminated on the resin film constituting the base material layer 1 by melt extrusion or solution coating of the adhesive constituting the adhesive layer 2. After being laminated and dried by (liquid coating), the adhesive layer 2 is formed by baking at a temperature equal to or higher than the melting point of the adhesive. By performing baking, the adhesive strength between the metal layer 3 and the adhesive layer 2 is improved. Similarly, for a multilayer film in which the metal layer 3 and the adhesive layer 2 prepared in advance in the thermal laminating method are laminated, the adhesive constituting the adhesive layer 2 is melt-extruded or solution into the metal foil constituting the metal layer 3 in the same manner. After being laminated by coating and dried, it is formed by baking at a temperature equal to or higher than the melting point of the adhesive constituting the adhesive layer 2.

  The laminate A is formed by the sand lamination method, for example, by melting and extruding the adhesive constituting the adhesive layer 2 onto the upper surface of the metal layer 3 and bonding the resin film constituting the base material layer 1 to the metal layer. Can be performed. At this time, it is desirable that the resin film is bonded and temporarily bonded, and then heated again to perform the main bonding. In the sand lamination method, the adhesive layer 2 may be multilayered with different resin types. In this case, a multilayer film in which the base material layer 1 and the adhesive layer 2 are laminated is prepared in advance, the adhesive constituting the adhesive layer 2 is melt-extruded on the upper surface of the metal layer 3, and the multilayer resin film and the thermal lamination method are used. What is necessary is just to laminate. Thereby, the adhesive layer 2 which comprises a multilayer film, and the adhesive layer 2 laminated | stacked on the upper surface of the metal layer 3 adhere | attach, and the two-layer adhesive layer 2 is formed. When the adhesive layer 2 is multilayered with different resin types, a multilayer film in which the metal layer 3 and the adhesive layer 2 are laminated is prepared in advance, and the adhesive constituting the adhesive layer 2 is melted on the base material layer 1 It may be extruded and laminated with the adhesive layer 2 on the metal layer 3. Thereby, the adhesive layer 2 composed of two different adhesives is formed between the multilayer resin film and the base material layer 1.

  Next, the sealant layer 4 is laminated on the metal layer 3 of the laminate A. Lamination of the sealant layer 4 on the metal layer 3 of the laminate A can be performed by a coextrusion method, a thermal lamination method, a sand lamination method, a coating method, or a combination thereof. For example, when the adhesive layer 5 is not provided, the sealant layer 4 can be formed on the metal layer 3 by melt extrusion, thermal lamination, coating, or the like. When the adhesive layer 5 is provided, the sealant layer 4 can be formed by the same method after the adhesive layer 5 is formed on the metal layer 3 by a melt extrusion method, a thermal laminating method, a coating method, or the like. Further, a co-extrusion method in which the adhesive layer 5 and the sealant layer 4 are simultaneously melt-extruded on the metal layer 3 may be performed. Moreover, while the adhesive layer 5 is melt-extruded on the metal layer 3, a sand laminating method in which the film-like sealant layer 4 is bonded can also be performed. When the sealant layer 4 is formed of two layers, for example, one layer of the adhesive layer 5 and the sealant layer 4 is coextruded on the metal layer 3, and then another layer of the sealant layer 4 is pasted by a thermal lamination method. The method of attaching is mentioned. Further, there may be mentioned a method in which one layer of the adhesive layer 5 and the sealant layer 4 is coextruded on the metal layer 3 and another layer of the film-like sealant layer 4 is bonded. In addition, when making the sealant layer 4 into three or more layers, the sealant layer 4 can be further formed by a melt extrusion method, a thermal lamination method, a coating method, or the like.

  As described above, it comprises: base material layer 1 / adhesive layer 2 provided as needed / metal layer 3 whose surface is subjected to chemical conversion treatment as needed / adhesive layer 5 / sealant layer 4 provided as needed A laminate is formed. In order to strengthen the adhesiveness of the adhesive layer 2, it may be further subjected to heat treatment such as hot roll contact, hot air, near or far infrared irradiation, dielectric heating, heat resistance heating and the like. Examples of such heat treatment conditions include 150 to 250 ° C. and 1 to 10 hours.

  Moreover, 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, and ozone treatment may be performed.

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

  Specifically, a battery element including at least a positive electrode, a negative electrode, and an electrolyte is formed with a flange (sealant layer) on the periphery of the battery element in a state in which a metal terminal connected to each of the positive electrode and the negative electrode protrudes outward. The area | region which mutually contacts) can be formed, and it coat | covers with the battery packaging material of this invention. Next, the battery sealed with the battery packaging material of the present invention is provided by heat-sealing and sealing the sealant layers of the flange part. When the battery element is accommodated using the battery packaging material of the present invention, the battery packaging material of the present invention is used so that the sealant layer 4 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. 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.

  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 1-16 and Comparative Example 1-4
[Manufacture of battery packaging materials]
On a base material layer made of a biaxially stretched nylon film (thickness 25 μm), a metal layer made of an aluminum foil (thickness 40 μm) subjected to chemical conversion treatment on both surfaces was laminated by a dry lamination method. Specifically, a two-component urethane adhesive (a polyester-based main agent and an isocyanate-based curing agent) was applied to one surface of the aluminum foil, and an adhesive layer (thickness 4 μm) was formed on the metal layer. Next, after the adhesive layer and the base material layer on the metal layer were pressure-heat bonded, a laminate of base material layer / adhesive layer / metal layer was prepared by performing an aging treatment at 60 ° C. for 24 hours. . In addition, the chemical conversion treatment of the aluminum foil used as the metal layer is a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid with a chromium coating amount of 10 mg / m ² (dry weight)
The film was applied to both surfaces of the aluminum foil by a roll coating method and baked for 20 seconds under the condition that the film temperature was 180 ° C. or higher.

  Next, the first sealant layer and the second sealant are formed on the metal layer 3 by co-extruding the resin forming the first sealant layer and the resin forming the second sealant layer in a molten state on the metal layer side of the laminate. The layers were laminated. The resin, thickness, and melting point forming each sealant layer are as shown in Table 1. For the resin forming the second sealant layer, the ethylene unit content (mol%), isotactic fraction (%), and n-decane-soluble component amount (% by mass) are shown in Tables 1 and 2, respectively. Two. Thus, a battery packaging material comprising a laminate in which the base material layer 1 / adhesive layer 2 / metal layer 3 / first sealant layer 4a / second sealant layer 4b were laminated in order was obtained.

The melting point of each resin is a value measured by a differential scanning calorimeter (DSC). The ethylene unit content and the isotactic fraction (mm) are values obtained by measurement of ¹³ C nuclear magnetic resonance spectra, respectively. The amount of the component soluble in n-decane of the resin was calculated from the amount of the resin that was not dissolved by stirring 100 parts by mass of resin in 1000 parts by mass of n-decane at 80 ° C.

  Next, the battery packaging materials obtained in Examples 1 to 16 and Comparative Examples 1 to 4 were evaluated for insulation after the seal portion was bent as follows.

<Evaluation of insulation after bending the seal part once>
The battery packaging material was cut into 60 mm (MD direction) × 60 mm (TD direction) sheet pieces. Next, these sheet pieces were folded in the MD direction, and two opposing sides were heat-sealed with a width of 7 mm to prepare a pouch-type exterior body having an opening on one side. Next, the obtained exterior body is sealed with a lithium ion battery main body including cells so that the metal terminal extends to the outside from one side of the opening, and the opening is formed while holding the metal terminal with the electrolytic solution. A lithium ion battery was produced by hermetically sealing with a width of 3 mm. At this time, the heat sealing was performed under the conditions of a surface pressure of 2.0 MPa, a sealing temperature of 170 ° C., and a sealing time of 5.0 seconds. Next, the heat-sealed portion of the obtained lithium ion battery was bent inward and returned to its original state. Next, the insulation evaluation test with respect to a crack was implemented using the impulse application system (Nippon Technate make, a lithium ion battery insulation tester). First, 20 lithium ion batteries were prepared, and an impulse voltage of 100 V was applied between the negative electrode terminal of each lithium ion battery and the aluminum foil, and the voltage drop after 99 msec was within 20 V. Passed. Table 1 shows the percentage of products that passed.

The resins listed in Table 1 are as follows.
PPa (1): acid-modified random polypropylene, melting point 160 ° C.
PPa (2): acid-modified random polypropylene, melting point 140 ° C.
PP (1): random polypropylene, melting point 150 ° C.
PP (2): random polypropylene, melting point 155 ° C.
PP (3): random polypropylene, melting point 140 ° C.
PP (4): random polypropylene, melting point 145 ° C.
PP (5): random polypropylene, melting point 150 ° C.
PP (6): random polypropylene, melting point 155 ° C.
PP (7): random polypropylene, melting point 130 ° C.
PP (8): random polypropylene, melting point 135 ° C.
PP (9): random polypropylene, melting point 156 ° C.
PP (10): random polypropylene, melting point 141 ° C.
PP (11): random polypropylene, melting point 157 ° C.
PP (12): random polypropylene, melting point 138 ° C.

  As shown in Table 1, in each of the battery packaging materials of Examples 1 to 16 using random polypropylene having an isotactic fraction (mm) of 99% or less, the seal portion was bent once. In the subsequent evaluation of insulation, the percentage of acceptable products was as high as 75% or more. On the other hand, in Comparative Examples 1 to 4 in which the isotactic fraction (mm) was 99.5%, the ratio of acceptable products was very high in the insulation evaluation after the heat seal portion was bent once. It was low.

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

Claims (8)

  A resin composition for a sealant layer of a battery packaging material, comprising a polyolefin resin having an isotactic fraction (mm) of 99% or less.   The resin composition according to claim 1, wherein the polyolefin-based resin has an ethylene unit content of 0.1 to 10 mol%.   The said polyolefin resin is a resin composition of Claim 1 or 2 whose amount of components soluble in n-decane in 80 degreeC is 0.1-15 mass%.   The resin composition according to claim 1, wherein the polyolefin-based resin contains at least propylene as a constituent monomer. A battery packaging material comprising a laminate having at least a base material layer, a metal layer, and a sealant layer in this order,
The battery packaging material in which the said sealant layer contains the layer formed with the resin composition in any one of Claims 1-4.   The battery packaging material according to claim 5, wherein the layer formed of the resin composition has a thickness of 1 to 20 μm.   The battery packaging material according to claim 5 or 6, wherein the sealant layer has a thickness of 40 µm or less.   A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is sealed with the battery packaging material according to claim 5.