Battery adhesive, battery laminate, battery packaging material, and tab lead

Abstract

One embodiment of the present invention relates to a battery adhesive, a battery laminate, a battery packaging material, or a tab lead, wherein the battery adhesive satisfies requirements (i) to (iii).　The battery adhesive (i) includes a graft-modified product of at least one base polymer selected from polyolefins with at least one carbodiimide monomer selected from the group consisting of a compound represented by formula (1) and a compound represented by formula (2), (ii) includes 0.1-50 mmol of carbodiimide groups per 100g of the battery adhesive, and (iii) has a density of 0.870-0.940 g / cm3, wherein: in formula (1), R1 is a hydrogen atom or a methyl group, and R2 is an alkyl group or aryl group which may have a substituent; and in formula (2), R3 is a hydrogen atom or a methyl group, R4 is an alkyl group or aryl group which may have a substituent, and m is an integer of 2 or more.

Description

Battery adhesives, battery stacks, battery packaging materials and tab leads

[0001] An embodiment of the present invention relates to a battery adhesive (battery adhesive), a battery stack (battery stack), a battery packaging material (battery packaging material), or a tab lead.

[0002] In recent years, lithium-ion batteries have been attracting attention due to their high energy density. While metal cans have traditionally been used as packaging for lithium-ion batteries (battery packaging), multilayer films have recently come into use because they are lightweight, have excellent heat dissipation properties, and can be produced at low cost.

[0003] The multilayer film used as the battery packaging material is a multilayer film containing an aluminum (foil) layer to prevent the penetration of moisture and the like into the battery contents (positive electrode, separator, negative electrode, electrolyte, etc.), and the multilayer film bonds the aluminum layer to other layers that are adherends with an adhesive.

[0004] As such adhesives, Patent Document 1 describes an adhesive made of maleic anhydride-modified polypropylene, and Patent Document 2 describes an adhesive containing a polyolefin resin having a carboxy group and a polyfunctional isocyanate compound.

[0005] JP 2023-40153 A JP 2010-92703 A

[0006] As described in Patent Documents 1 and 2, carboxyl group-modified polyolefins have been used as adhesives (for batteries) for conventional multilayer films for batteries. These multilayer films for batteries come into contact with an electrolyte, and the inventors' investigations have revealed that when conventional multilayer films for batteries come into contact with such an electrolyte, the adhesive strength of the adhesive (for batteries), particularly the adhesive strength between the aluminum layer and the adhesive layer, decreases over time, making interlayer delamination more likely to occur.

[0007] One embodiment of the present invention provides a battery adhesive capable of forming an adhesive layer whose adhesive strength is unlikely to decrease even after contact with an electrolyte solution, as well as a battery laminate, battery packaging material, and tab lead that use the battery adhesive.

[0008] A configuration example of the present invention is as follows.

[0009] [1] A battery adhesive that satisfies the following requirements (i) to (iii): (i) the adhesive comprises at least one base polymer selected from polyolefins, graft-modified with at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2), (ii) the adhesive contains 0.1 to 50 mmol of carbodiimide groups per 100 g of the battery adhesive, and (iii) the adhesive has a density of 0.870 to 0.940 g / cm ３ is

[0010] [In formula (1), R １ is a hydrogen atom or a methyl group, and R ２ represents an alkyl group or an aryl group which may have a substituent, and in formula (2), R ３ is a hydrogen atom or a methyl group, and R ４ represents an alkyl group or an aryl group which may have a substituent, and m is an integer of 2 or more.

[0011] [2] The R ２ is an aliphatic hydrocarbon group having 4 to 20 carbon atoms and including an alicyclic ring.

[0012] [3] The R ３ is a methyl group, and R ４ is a branched, non-cyclic alkyl group, and m is 2.

[0013] [4] The battery adhesive according to any one of [1] to [3], wherein the base polymer is a polymer that does not have at least one active hydrogen-containing group selected from a carboxy group, an acid anhydride group, an amino group, a hydroxy group, and a thiol group.

[0014] [5] A battery laminate comprising a metal layer and an adhesive layer formed from the battery adhesive according to any one of [1] to [4]. [6] The battery laminate according to [5], wherein the metal layer is an aluminum layer. [7] A battery packaging material or tab lead comprising the battery laminate according to [6].

[0015] According to one embodiment of the present invention, it is possible to provide a battery adhesive capable of forming an adhesive layer whose adhesive strength is resistant to deterioration even after contact with an electrolytic solution, as well as a battery laminate, battery packaging material, and tab lead using the battery adhesive. In particular, according to one embodiment of the present invention, it is possible to form an adhesive layer that has higher adhesive strength after contact with an electrolytic solution than before contact with the electrolytic solution, and by using such an adhesive layer, it is possible to provide a battery laminate, battery packaging material, and tab lead that are stable over the long term (resistant to delamination), and thus a highly reliable battery can be provided.

[0016] <Battery Adhesive> A battery adhesive according to one embodiment of the present invention (hereinafter also referred to as "the adhesive") satisfies the following requirements (i) to (iii): (i) It contains a graft-modified product (hereinafter also referred to as "the modified product") of at least one base polymer selected from polyolefins with at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2), (ii) It contains 0.1 to 50 mmol of carbodiimide groups per 100 g of the battery adhesive, and (iii) It has a density of 0.870 to 0.940 g / cm ３ is

[0017] [In formula (1), R １ is a hydrogen atom or a methyl group, and R ２ represents an alkyl group or an aryl group which may have a substituent, and in formula (2), R ３ is a hydrogen atom or a methyl group, and R ４ represents an alkyl group or an aryl group which may have a substituent, and m is an integer of 2 or more.

[0018] The amount of carbodiimide groups in the adhesive is 0.1 to 50 mmol, preferably 0.2 to 20 mmol, and more preferably 0.5 to 10 mmol per 100 g of the adhesive. When the amount of carbodiimide groups is within this range, the adhesive exhibits excellent adhesion to metal layers, particularly aluminum layers, and an adhesive layer can be easily formed that has higher adhesive strength after contact with the electrolytic solution than before contact with the electrolytic solution. The amount of carbodiimide groups is specifically measured by the method described in the Examples below.

[0019] The density of this adhesive, measured in accordance with JIS K 7210, is 0.870 to 0.940 g / cm ３ and preferably 0.880 to 0.925 g / cm ３ , more preferably 0.890 to 0.920 g / cm ３ When the density is within the above range, an adhesive layer having excellent adhesion to a metal layer, particularly an aluminum layer, can be easily obtained.

[0020] The melt flow rate (MFR) of this adhesive, measured at 190°C under a load of 2.16 kg in accordance with JIS K 7210, is preferably 0.1 to 10 g / 10 min, more preferably 0.2 to 5 g / 10 min. An MFR within this range is preferred because it allows the desired adhesive layer or battery laminate to be easily formed by a desired molding method.

[0021] The adhesive is not particularly limited as long as it contains the modified product, and may consist solely of the modified product. Because the adhesive contains the modified product, it is possible to form an adhesive layer with high adhesive strength on metal layers, particularly aluminum layers, even with a short heat-sealing time. The modified product is a graft modified product, rather than a block copolymer or random copolymer of an olefinic monomer such as ethylene or propylene with the carbodiimide monomer, and the adhesive exhibits the above-mentioned effects by using the modified product.

[0022] The adhesive may contain one or more types of modified compounds. The content of the modified compounds in the adhesive is not particularly limited, but from the viewpoints of moldability, controllability of adhesive performance, economic efficiency, etc., it is usually 0.5% by mass or more, preferably 1% by mass or more, and usually 60% by mass or less, preferably 50% by mass or less.

[0023] The adhesive may contain the modified product and one or more olefin polymers other than the modified product. The olefin polymer that may be used in the adhesive is not particularly limited as long as it is a polymer made from an olefin, and various known olefin polymers can be used. Specific examples include homopolymers or copolymers of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene (e.g., high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), medium-density polyethylene, high-density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, low-crystalline or amorphous ethylene-propylene random copolymers, ethylene-1-butene random copolymers, and propylene-1-butene random copolymers), ethylene-vinyl acetate copolymers (EVA) or saponified products thereof, ethylene-(meth)acrylic acid copolymers or metal salts (ionomers) thereof, ethylene-cyclic olefin copolymers, and polymers obtained by graft-modifying these (co)polymers with polar compounds such as silane compounds. Among these, when the present adhesive contains a certain present modified product, the olefin polymer is preferably the same polymer as the base polymer used in the synthesis of the present modified product, from the viewpoints of excellent compatibility and ease of obtaining an present adhesive that better exhibits the desired effects.

[0024] The olefin-based polymer may be a polymer using only biomass-derived raw materials as its raw materials (e.g., olefin), a polymer using only fossil fuel-derived raw materials, or a polymer using both biomass-derived raw materials and fossil fuel-derived raw materials. The olefin-based polymer is preferably a polymer using biomass-derived raw materials from the viewpoint of reducing environmental load (mainly greenhouse gas emissions).

[0025] In this specification, biomass-derived raw materials refer to raw materials made from any (renewable) natural raw materials and their residues, such as those derived from plants or animals, including fungi, yeasts, algae, and bacteria, and are, for example, raw materials that contain carbon. １４ C isotope 1×10 －１２ Examples of such raw materials include raw materials containing biomass-derived raw materials in a proportion of about 100 pMC, and having a biomass carbon concentration (unit: pMC) measured in accordance with ASTM D6866. Biomass-derived raw materials can be obtained, for example, by conventionally known methods. For a certain polymer, if the production conditions of the polymer, such as the polymerization catalyst, polymerization process, and polymerization temperature, are the same, even if the polymer contains a biomass-derived raw material, １４ C isotope 1×10 －１２ ~1 x 10 －１４ The molecular structure of the polymers containing biomass-derived raw materials is the same as that of polymers made from fossil fuel-derived raw materials, except for the proportion of biomass-derived raw materials. Therefore, it is believed that the performance of polymers containing biomass-derived raw materials is the same as that of polymers made from fossil fuel-derived raw materials.

[0026] When the adhesive contains the olefin-based polymer, the content of the olefin-based polymer in the adhesive is not particularly limited, but from the standpoints of moldability, controllability of adhesive performance, economy, etc., the content is usually 40% by mass or more, preferably 50% by mass or more, and usually 99.5% by mass or less, preferably 99% by mass or less.

[0027] The adhesive may contain various additives other than the modified product and the olefin polymer, as needed, as long as they do not impair the objectives of the present invention. Examples of such additives include softeners, stabilizers, fillers, antioxidants, nucleating agents, waxes, thickeners, mechanical stability agents, leveling agents, wetting agents, film-forming aids, crosslinking agents, preservatives, rust inhibitors, pigments, dispersants, antifreeze agents, antifoaming agents, tackifiers, other thermoplastic polymers, water, and organic solvents. These may be used alone or in combination of two or more. The additives may be made solely from biomass-derived raw materials, solely from fossil fuel-derived raw materials, or both from biomass and fossil fuel-derived raw materials.

[0028] The adhesive can be used in various known adhesive forms, such as a water-dispersed adhesive, an organic solvent adhesive, or a hot-melt adhesive.

[0029] The adhesive for use with the present adhesive is not particularly limited as long as it is a material used in batteries, particularly battery packaging and tab leads, but examples include layers containing or consisting of metals; thermoplastic resins such as polyester, polyphenylene sulfide, polyamide, polyacetal, polycarbonate, poly(meth)acrylate, olefin polymers, polystyrene, rubber, modified fluororesin, biomass plastic, biodegradable polymer, and other engineering plastics; and thermosetting resins. Among these, the present adhesive has excellent adhesion to metal layers, particularly aluminum layers, and is therefore preferably used as an adhesive for these layers in order to better demonstrate the effects of the present invention.

[0030] <Modified Product> The modified product is a graft-modified product of at least one base polymer selected from polyolefins with at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2): In other words, the modified product is a graft-modified product in which at least one base polymer selected from polyolefins is graft-modified with at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2): Furthermore, the modified product can also be said to be a graft-modified product comprising at least one base polymer portion selected from polyolefins and a graft portion derived from at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2):

[0031] The graft ratio in the present modified product is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and preferably 8% by mass or less, more preferably 5% by mass or less, from the viewpoints of ease of synthesis of the present modified product, ease of obtaining a graft modified product having superior adhesiveness, and preventing the obtained graft modified product from becoming too hard, etc. The graft ratio is the mass of the structure derived from the carbodiimide monomer in the graft modified product, １ It can be determined by H-NMR measurement, specifically by the method described in the examples below.

[0032] [Carbodiimide Monomer] The carbodiimide monomer used when graft-modifying the base polymer is at least one selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2). Among these, the compound represented by the following formula (2) is preferred because it allows for the easy production of an adhesive having superior adhesion to metal layers, particularly aluminum layers. The carbodiimide monomer used when graft-modifying the base polymer may be of two or more types, but is usually of one type.

[0033] When conventionally used maleic anhydride or the like is used for graft modification, the water contained in the electrolyte reacts with the maleic anhydride or the like, generating an acid (e.g., hydrogen fluoride). It is believed that the generation of this acid (e.g., hydrogen fluoride) reduces the adhesive strength between the adhesive and the object being bonded. On the other hand, by using a carbodiimide monomer, the bond is less likely to break compared to modification with maleic anhydride or the like, and therefore acid (e.g., hydrogen fluoride) is less likely to be generated, thereby preventing the reduction in adhesive strength.

[0034] The carbodiimide monomer may be a monomer derived from biomass, a monomer derived from fossil fuel, or a monomer derived from biomass and fossil fuel, which is preferable from the viewpoint of reducing environmental load (mainly greenhouse gas reduction).

[0035]

[0036] In formula (1), R １ is a hydrogen atom or a methyl group, and is preferably a hydrogen atom in view of the ease with which the present modified compound having a high grafting rate can be obtained.

[0037] In formula (1), R ２ is an alkyl group or aryl group which may have a substituent. The alkyl group which may have a substituent may be chain-like (it may be linear or branched) or may contain an alicyclic ring. The number of carbon atoms in the alkyl group which may have a substituent is preferably 1 or more, more preferably 3 or more, and preferably 20 or less, more preferably 12 or less, and even more preferably 8 or less. The number of carbon atoms in the aryl group which may have a substituent is preferably 5 or more, more preferably 6 or more, and preferably 20 or less, more preferably 12 or less, and even more preferably 8 or less.

[0038] Examples of the substituent that the alkyl group and aryl group may have include a halogen atom, a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a carboxylic acid ester group having 1 to 8 carbon atoms, a sulfonic acid ester group having 1 to 8 carbon atoms, a carbonyl group having 1 to 8 carbon atoms, an amide group having 1 to 8 carbon atoms, an amino group having 1 to 8 carbon atoms, a sulfide group having 1 to 8 carbon atoms, a phosphate ester group having 1 to 8 carbon atoms, an alkylsilyl group having 1 to 8 carbon atoms, and an alkoxysilyl group having 1 to 8 carbon atoms.

[0039] Among these, from the viewpoints of the solubility of the carbodiimide monomer, ease of availability, ease of purification of the resulting graft-modified compound, etc., R2 is preferably an aliphatic hydrocarbon group containing an alicyclic ring and having 4 to 20 carbon atoms, and more preferably an alicyclic hydrocarbon group having 5 to 7 carbon atoms. Examples of the alicyclic ring include a cyclobutyl ring, a cyclopentyl ring, a cyclohexyl ring, a cycloheptyl ring, and rings having a hydrocarbon group. The alicyclic ring may also be a polycyclic ring such as an adamantyl ring or a methyladamantyl ring.

[0040]

[0041] In formula (2), R ３ is a hydrogen atom or a methyl group, and a methyl group is preferred in that it makes it easy to obtain an adhesive having excellent adhesive strength to metal layers, particularly aluminum layers.

[0042] In formula (2), R ４is an alkyl group or aryl group which may have a substituent. The alkyl group which may have a substituent may be chain-like (it may be linear or branched) or may contain an alicyclic ring. The number of carbon atoms in the alkyl group which may have a substituent is preferably 1 or more, more preferably 3 or more, and preferably 20 or less, more preferably 12 or less, and even more preferably 8 or less. The number of carbon atoms in the aryl group which may have a substituent is preferably 5 or more, more preferably 6 or more, and preferably 20 or less, more preferably 12 or less, and even more preferably 8 or less. Examples of the alicyclic ring include a cyclobutyl ring, a cyclopentyl ring, a cyclohexyl ring, a cycloheptyl ring, and rings thereof which have a hydrocarbon group. The alicyclic ring may also be a polycyclic ring such as an adamantyl ring or a methyladamantyl ring.

[0043] Examples of the substituent that the alkyl group and aryl group may have include a halogen atom, a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a carboxylic acid ester group having 1 to 8 carbon atoms, a sulfonic acid ester group having 1 to 8 carbon atoms, a carbonyl group having 1 to 8 carbon atoms, an amide group having 1 to 8 carbon atoms, an amino group having 1 to 8 carbon atoms, a sulfide group having 1 to 8 carbon atoms, a phosphate ester group having 1 to 8 carbon atoms, an alkylsilyl group having 1 to 8 carbon atoms, and an alkoxysilyl group having 1 to 8 carbon atoms.

[0044] Among these, the R ４ As the alkyl group, a branched, non-cyclic alkyl group is preferred, and a branched, non-cyclic alkyl group having 3 to 7 carbon atoms is more preferred, from the viewpoints of improving the stability of the carbodiimide group in air and when heated, increasing the yield when synthesizing the present modified compound, and reducing production costs, and of easily obtaining the present adhesive having excellent adhesive strength to metal layers, particularly aluminum layers. ４ When the compound does not have a ring, the steric hindrance caused by the ring structure is suppressed, and the reactivity of the carbodiimide group becomes good.

[0045] Preferred examples of the branched, non-ring alkyl group include an isopropyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a 1-methylbutyl group, a 1,2-dimethylpropyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylpropyl group, a 1,1-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1-methylpentyl group, a 1,2-dimethylbutyl group, a 1,3-dimethylbutyl group, a 1,2,2-trimethylpropyl group, a 2-methylpentyl group, a 2 , 2-dimethylbutyl group, 2,3-dimethylbutyl group, 2-ethylbutyl group, 3-methylpentyl group, 3,3-dimethylbutyl group, 4-methylpentyl group, 1-ethyl-2-methylpropyl group, 1-ethylbutyl group, 1,1-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1-ethyl-1-methylpropyl group, 1-methylhexyl group, 1,2-dimethylpentyl group, 1,3-dimethylpentyl group, 1,4-dimethylpentyl group, 1,2,3-trimethylbutyl group, 1 , 2,2-trimethylbutyl group, 1,3,3-trimethylbutyl group, 2-methylhexyl group, 2,3-dimethylpentyl group, 2,4-dimethylpentyl group, 2,3,3-trimethylbutyl group, 1,1-dimethylpentyl group, 1,1,2-trimethylbutyl group, 1,1,3-trimethylbutyl group, 1,1,2,2-tetramethylpropyl group, 2,2-dimethylpentyl group, 2,2,3-trimethylbutyl group, 3-methylhexyl group, 3,4-dimethylpentyl group, 3,3-dimethyl Examples of suitable groups include tert-butyl, 1-ethylpentyl, 1-ethyl-2-methylbutyl, 1-ethyl-3-methylbutyl, 1-ethyl-2,2-dimethylpropyl, 2-ethylpentyl, 2-ethyl-3-methylbutyl, 1-ethyl-1-methylbutyl, 1-ethyl-1,2-dimethylpropyl, 3-ethylpentyl, 1,1-diethylpropyl, 2,2-diethylpropyl, 1-propylbutyl, diisopropylmethyl, and 1-isopropylbutyl. Among these, the tert-butyl group is preferred from the viewpoint that an adhesive having excellent adhesive strength to metal layers, particularly aluminum layers, can be easily obtained.

[0046] In formula (2), m is an integer of 2 or more, and from the viewpoints of the solubility of the carbodiimide monomer, ease of availability, ease of purification of the resulting graft-modified product, etc., m is preferably an integer of 2 to 6, more preferably an integer of 2 to 4, and particularly preferably 2.

[0047] [Base Polymer] The base polymer before being graft-modified with the carbodiimide monomer is at least one polymer selected from polyolefins. Specific examples of the olefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene. The polyolefin may be a homopolymer of one of these olefins, a copolymer of two or more of these olefins, or a copolymer of one or more of these olefins with one or more comonomers described below. Among these, the polyolefin is preferably at least one polymer selected from ethylene-based polymers, propylene-based polymers, and butene-based polymers. When a solvent is used during the graft reaction, at least one polymer selected from ethylene-based polymers and propylene-based polymers is more preferred from the viewpoints of excellent solubility in the solvent and excellent separability from impurities after the graft reaction. The base polymer of the present modified product may be two or more types, but is usually one type.

[0048] The base polymer is preferably a polymer that does not have at least one active hydrogen-containing group selected from a carboxy group, an acid anhydride group, an amino group, a hydroxy group, and a thiol group, in order to more effectively achieve the effects of the present invention.Furthermore, the base polymer is preferably a polymer that does not have a carboxylic acid derivative group such as an acid halide, amide, imide, or ester, or a group that is easily converted by water or the like into a group having an active hydrogen, such as an epoxy group, in order to more effectively achieve the effects of the present invention.

[0049] The weight-average molecular weight (Mw) of the base polymer is not particularly limited, but from the viewpoint of ease of synthesis of the present modified product, it is preferably 100,000 or more, more preferably 150,000 or more, and preferably 1,000,000 or less, more preferably 700,000 or less. The number-average molecular weight (Mn) of the base polymer is also not particularly limited, but for the same reasons, it is preferably 10,000 or more, more preferably 20,000 or more, and preferably 500,000 or less, more preferably 300,000 or less. The molecular weight distribution (Mw / Mn) of the base polymer is also not particularly limited, but is preferably 1.5 or more, more preferably 2.0 or more, and preferably 7.0 or less, more preferably 6.0 or less.

[0050] The Mw and Mn values ​​were measured under the following conditions using a Tosoh Corporation HLC-8321 GPC / HT type gel permeation chromatograph (GPC). Separation columns: TSKgel GMH6-HT (2 columns) and TSKgel GMH6-HTL (2 columns) (both 7.5 mm ID x 30 cm, Tosoh Corporation). Column temperature: 140°C. Mobile phase: o-dichlorobenzene (containing 0.025% dibutylhydroxytoluene (BHT)). Development rate: 1.0 mL / min. Sample concentration: 0.1% (w / v). Sample injection volume: 0.4 mL. Detector: differential refractometer. Apparatus calibration: Calibrated using monodisperse polystyrene (Tosoh Corporation, #3 standard set).

[0051] The base polymer can be synthesized by a conventionally known method, or a commercially available product may be used. The conventionally known method is not particularly limited, and examples thereof include a method using a coordination polymerization catalyst system containing a transition metal. Specific examples include a synthesis method in which an olefin such as ethylene or propylene is (co)polymerized with a comonomer described below, if necessary, in the presence of a catalyst such as a magnesium chloride-supported titanium catalyst, a vanadium catalyst containing a soluble vanadium compound and an alkylaluminum halide compound, or a metallocene catalyst containing a metallocene compound and an organoaluminum oxy compound.

[0052] The base polymer may be made using only biomass-derived raw materials, only fossil fuel-derived raw materials, or both biomass-derived raw materials and fossil fuel-derived raw materials as raw materials (e.g., monomers such as olefins and comonomers described below). It is preferable that the base polymer be made using biomass-derived raw materials from the viewpoint of reducing environmental load (mainly greenhouse gas emissions).

[0053] [Ethylene-Based Polymer] The ethylene-based polymer is not particularly limited as long as the content of ethylene-derived structural units in the polymer is 50% by mass or more, and may be an ethylene homopolymer or a copolymer of ethylene and a comonomer. In the case of a copolymer, the structure thereof is not particularly limited.

[0054] Examples of the comonomer include at least one monomer selected from propylene, α-olefins having 4 to 20 carbon atoms, and conjugated polyenes. Among these, propylene and α-olefins having 4 to 20 carbon atoms are preferred. The α-olefins having 4 to 20 carbon atoms may be linear or branched, and examples thereof include 1-butene, 2-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. The content of the comonomer-derived structural unit in the ethylene polymer is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoints of preventing blocking of pellets or powder and making them easy to handle. In this specification, an ethylene-based polymer having a content of propylene-derived or butene-derived structural units of 50 mass % is referred to as an ethylene-based polymer.

[0055] [Propylene-Based Polymer] The propylene-based polymer is not particularly limited as long as it is a polymer in which the content of propylene-derived structural units in the polymer is 50 mass% or more, and may be a propylene homopolymer or a copolymer of propylene and a comonomer. The structure of these (co)polymers is not particularly limited.

[0056] Examples of the comonomer include at least one monomer selected from ethylene, α-olefins having 4 to 20 carbon atoms, and conjugated polyenes. Among these, ethylene and α-olefins having 4 to 20 carbon atoms are preferred. Examples of the α-olefins having 4 to 20 carbon atoms include the same α-olefins as the α-olefins having 4 to 20 carbon atoms listed in the section on ethylene-based polymers. The content of the comonomer-derived structural units in the propylene-based polymer is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoints of preventing blocking of pellets or powder and making them easy to handle. In this specification, a propylene-based polymer having a butene-derived structural unit content of 50% by mass is referred to as a propylene-based polymer.

[0057] [Butene Polymer] The butene polymer is not particularly limited as long as the content of butene-derived structural units in the polymer is 50% by mass or more, and may be a homopolymer of butene, particularly 1-butene, or a copolymer of butene (particularly 1-butene) and a comonomer. The structure of these (co)polymers is not particularly limited.

[0058] Examples of the comonomer include at least one monomer selected from ethylene, propylene, α-olefins having 5 to 20 carbon atoms, and conjugated polyenes. Among these, ethylene, propylene, and α-olefins having 5 to 20 carbon atoms are preferred. Examples of the α-olefins having 5 to 20 carbon atoms include the same α-olefins as the α-olefins having 5 to 20 carbon atoms listed in the section on ethylene-based polymers. The content of the structural units derived from the comonomer in the butene-based polymer is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoints of preventing blocking of pellets or powder and making them easy to handle.

[0059] <Method for synthesizing the modified product> The method for synthesizing the modified product is not particularly limited, as long as a graft modified product can be obtained by graft-modifying the base polymer with the carbodiimide monomer. From the viewpoint of easily synthesizing the modified product, a method is preferred in which a radical initiator and the carbodiimide monomer are added to a solution in which the base polymer is dissolved or dispersed in a solvent, preferably a solution in which the base polymer is dissolved in an organic solvent, and the reaction (graft reaction) is carried out. Note that, when a reaction apparatus having a stirring capacity capable of uniformly flowing the base polymer is used, a solvent need not be used. According to this method, graft polymerization occurs, resulting in a graft modified product.

[0060] The amount of the carbodiimide monomer used in the grafting reaction is preferably 10 to 1,000 mol, more preferably 10 to 800 mol, per mol of the base polymer, from the viewpoints that the present modified product having a graft rate within the above range can be easily obtained and that the production of a polymer of the carbodiimide monomer itself (hereinafter also referred to as a "non-grafted polymer") can be suppressed.

[0061] Examples of the radical initiator include organic peroxides and azo compounds, and specific examples thereof include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoate)hexyne-3, 1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(te Examples of the peroxide include organic peroxides such as tert-butylperoxyhexane, tert-butyl perbenzoate, tert-butyl perphenyl acetate, tert-butyl perisobutyrate, tert-butyl per-sec-octoate, tert-butyl perpivalate, cumyl perpivalate, tert-butyl perdiethyl acetate, and tert-butylperoxyisopropyl monocarbonate; and azo compounds such as azobisisobutyronitrile and dimethylazoisobutyrate. Among these, organic peroxides such as dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,4-bis(tert-butylperoxyisopropyl)benzene, and tert-butylperoxyisopropyl monocarbonate are preferred. One or more of the radical initiators may be used.

[0062] The amount of the radical initiator used in the graft reaction is preferably 0.01 mol or more, more preferably 0.05 mol or more, and preferably 0.7 mol or less, more preferably 0.5 mol or less, per mol of carbodiimide monomer, from the viewpoints that the graft reaction occurs efficiently and the present modified product having a graft rate within the above range can be easily obtained.

[0063] The organic solvent is preferably an organic solvent that does not significantly inhibit the grafting reaction of the carbodiimide monomer and has affinity with the base polymer in the temperature range in which the grafting reaction is carried out. Specific examples of such organic solvents include aromatic hydrocarbon solvents such as benzene, toluene, and xylene, aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, and decane, alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and decahydronaphthalene, chlorinated hydrocarbon solvents such as chlorobenzene, dichlorobenzene, trichlorobenzene, methylene chloride, chloroform, carbon tetrachloride, and tetrachloroethylene, alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester solvents such as ethyl acetate and dimethyl phthalate, and ether solvents such as dimethyl ether, diethyl ether, di-n-amyl ether, tetrahydrofuran, and dioxyanisole. Alternatively, suspension polymerization or emulsion polymerization can be carried out using water as a solvent. One or more of these solvents may be used. It is preferable that the reaction solution be a homogeneous phase by using these solvents, but it is acceptable for the reaction solution to be a heterogeneous mixture of phases.

[0064] Since the grafting reaction is carried out in a region where the liquid containing the base polymer can be uniformly stirred, the concentration of the base polymer in the liquid is usually set to 50 to 500 g / L, but in order to achieve a high grafting rate, it is preferably 200 to 500 g / L.

[0065] The radical initiator and carbodiimide monomer may be added all at once to a liquid containing the base polymer (or the base polymer itself) to initiate the graft reaction, but in order to achieve a high grafting rate, it is preferable to carry out the graft reaction by sequentially adding them over a period of about 0.1 to 5 hours. When the radical initiator and carbodiimide monomer are added to the base polymer or a liquid in which the base polymer is dissolved or dispersed in a solvent, the order of addition is not particularly limited. For example, when these are added sequentially as described above, the radical initiator and carbodiimide monomer may be added sequentially, or the carbodiimide monomer may be added first and then the radical initiator may be added sequentially.

[0066] The grafting reaction is desirably carried out at a temperature of usually 60°C or higher, preferably 100°C or higher, usually 200°C or lower, preferably 160°C or lower, for usually 2 hours or longer, preferably 3 hours or longer, and usually 10 hours or shorter, preferably 8 hours or shorter.

[0067] The modified product obtained by the graft reaction may be purified and isolated by known methods such as filtration, centrifugation, reprecipitation, and / or washing to remove the solvent used, unreacted radical initiator and carbodiimide monomer, and by-produced non-grafted polymer. In this case, from the viewpoint of easily obtaining the adhesive having superior adhesive properties, it is desirable to purify and isolate the modified product so that the content of the non-grafted polymer contained in the modified product is preferably 5% by mass or less, more preferably 2% by mass or less.

[0068] <Battery Laminate> A battery laminate according to one embodiment of the present invention (hereinafter also referred to as "the laminate") includes an adhesive layer formed from the adhesive and a metal layer. In terms of further demonstrating the effects of the present invention, it is preferable that at least a portion of the adhesive layer be in contact with the metal layer.

[0069] Carboxy-modified polyolefins have been used as adhesives for conventional multilayer films for batteries. These multilayer films for batteries come into contact with an electrolyte solution, but the presence of water in the electrolyte solution generates acid, which presumably severs the bonds at the adhesive surface of the multilayer film for batteries, reducing the adhesive strength. On the other hand, the adhesive layer in the present laminate is resistant to a decrease in adhesive strength even after contact with the electrolyte solution. In particular, the adhesive strength increases after contact with the electrolyte solution compared to before contact with the electrolyte solution due to the action of the electrolyte solution. Therefore, the present laminate including such an adhesive layer is believed to be a battery laminate that is stable (resistant to delamination) over a long period of time.

[0070] The present laminate is used in batteries, and is particularly suitable for use as battery packaging (battery packaging) and tab leads. The battery is not particularly limited, but examples thereof include lithium ion secondary batteries. The present laminate is not limited to a laminated film (sheet) shape, and may be in any of various known shapes such as a hollow container or a bag.

[0071] The present laminate is not particularly limited as long as it includes the adhesive layer and the metal layer, and the adhesive layer may be present on one side or both sides of the metal layer, or may be present entirely or partially on these sides. The present laminate may include two or more of the adhesive layers, and may include two or more of the metal layers. When two or more adhesive layers are included, these layers may be the same layer or different layers. Similarly, when two or more metal layers are included, these layers may be the same layer or different layers.

[0072] The adhesive layer is a layer formed from the present adhesive. The content of the present adhesive in the adhesive layer is preferably 80 to 100 mass %, more preferably 90 to 100 mass %. The presence of the present modified product in the adhesive layer can be determined by infrared spectroscopic analysis.

[0073] The thickness of the adhesive layer is not particularly limited and may be appropriately selected depending on the application of the present laminate, but is preferably 2 to 1000 μm.

[0074] The metal layer refers to a layer containing a metal or a metal compound, and examples of such metals include aluminum, aluminum alloys, SUS (stainless steel), and titanium. Among these, aluminum and aluminum alloys are preferred, and aluminum is more preferred, in terms of better demonstrating the effects of the present invention. The metal layer may have an oxide coating or the like formed on its surface, or may be a layer whose surface has been treated by chemical conversion coating or the like. Furthermore, the surface of the metal layer may be subjected to a conventional surface treatment, such as corona treatment, to improve adhesive strength.

[0075] The thickness of the metal layer is not particularly limited, and may be the same as that of metal layers used in batteries, particularly battery packaging materials and tab leads, and is preferably 1 to 500 μm.

[0076] The method for producing the present laminate is not particularly limited and can employ any conventionally known method, specifically including (1) a method in which an adhesive layer is formed in advance from the present adhesive by press molding, extrusion molding, injection molding, etc., and then the formed adhesive layer and a metal layer are laminated together, and (2) a method in which an adhesive layer that has been extrusion molded, injection molded, calendar molded, etc. is heat-fused to a metal layer. Other examples include a method in which the present laminate is produced by applying the present adhesive onto a metal layer and drying the adhesive as necessary, and a method in which the metal layer is immersed in the present adhesive, the metal layer is removed from the present adhesive, and the adhesive on the metal layer is dried as necessary.

[0077] Examples of a method for laminating the adhesive layer and metal layer formed in the method (1) include a method of heat fusing using a calendar roll molding machine, a compression molding machine, etc. at a temperature equal to or higher than the temperature at which the adhesive layer melts. When producing a laminate by pressing (heat sealing) the adhesive layer and the metal layer using this compression molding machine, for example, when heat sealing is performed at 180°C, the present laminate with high adhesive strength can be formed even if the heat sealing time is set to a short time, preferably 20 seconds or less, more preferably 10 seconds or less, and even more preferably 5 seconds or less.

[0078] The present laminate is usually used by adhering the adhesive layer to a desired adherend (other layer). That is, the present laminate may be an adhesive body in which a metal layer, an adhesive layer, and an adherend (other layer) are laminated in this order. The present laminate may include two or more of the other layers. When two or more other layers are included, these layers may be the same layer or different layers.

[0079] Examples of the other layer include layers used in batteries, particularly battery packaging materials and tab leads, and are not particularly limited as long as they are layers other than adhesive layers and metal layers. Examples include layers containing or consisting of thermoplastic resins such as polyester, polyphenylene sulfide, polyamide, polyacetal, polycarbonate, poly(meth)acrylate, olefin-based polymers, polystyrene, rubber, modified fluororesin, biomass plastic, and other engineering plastics; thermosetting resins. Among these, a polypropylene layer is preferred because it can be suitably used in batteries, particularly battery packaging materials and tab leads. The polypropylene layer may be stretched, but is preferably unstretched.

[0080] The thickness of the other layer is not particularly limited, and may be the same as that of the layer used in the battery, particularly the battery packaging material, tab lead, etc., and is preferably 1 to 500 μm.

[0081] When manufacturing the present laminate including the other layers, the adhesive layer and the other layers may be molded in advance by a known method such as press molding, extrusion molding, or injection molding, and the present laminate may be manufactured using the resulting adhesive layer and other layers, or the present adhesive and the materials forming the other layers may be laminated by a known method such as co-extrusion molding, lamination molding, blow molding, or co-injection molding.

[0082] <Battery Packaging> A battery packaging material according to one embodiment of the present invention includes the present laminate, particularly the present laminate in which the metal layer is an aluminum layer. The battery packaging material may be a battery packaging material consisting of the present laminate (only), or may include a conventionally known layer included in a conventionally known battery packaging material.

[0083] Examples of the battery packaging material include a laminate in which the metal layer, the adhesive layer, and the inner layer are laminated in this order, or a packaging material (thermocompression-bonded body) in which one or two laminates in which the inner layer, the inner adhesive layer, the metal layer, the outer adhesive layer, and the outer layer are laminated in this order are thermocompressed so that the inner layers are in contact. The inner adhesive layer in the battery packaging material is the adhesive layer formed from the present adhesive. Note that the battery packaging material may have a conventionally known layer between these layers or on the surface of the laminate.

[0084] The inner layer may be the same as the other layers, and is preferably a polypropylene layer. The outer layer may be the same as the other layers, and is preferably a stretched or unstretched film such as a polyester film, a polyamide film, or a polypropylene film, in order to provide heat resistance during thermocompression bonding, formability during processing, pinhole resistance, insulation during distribution, etc., and may be a single layer or a multilayer film having two or more layers laminated thereon.

[0085] The outer adhesive layer may be any layer that bonds the outer layer and the metal layer, and may be an adhesive layer formed from the present adhesive, or may be a layer obtained using a conventionally known adhesive such as a dry lamination adhesive or a solventless adhesive.

[0086] The battery packaging material typically packages a positive electrode, a negative electrode, a separator, and an electrolyte solution, and is used as a battery. The positive electrode and the negative electrode are typically disposed opposite each other with a space between them, with the separator interposed between them, so as to be in contact with the electrolyte solution. The electrolyte solution is not particularly limited, and examples thereof include electrolyte solutions containing an organic solvent such as ethylene carbonate, diethyl carbonate, dimethyl carbonate, or vinylene carbonate; or a lithium salt such as lithium hexafluorophosphate.

[0087] <<Tab Lead>> A tab lead according to one embodiment of the present invention includes the present laminate, and in particular includes the present laminate in which the metal layer is an aluminum layer. The tab lead may be a tab lead made up of (only) the present laminate, or may include a conventionally known layer included in a conventionally known tab lead.

[0088] Hereinafter, one embodiment of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0089] <Method for measuring graft ratio> The graft ratio of the graft polymer obtained in the following synthesis example was measured using an AVANCE III cryo-500 nuclear magnetic resonance spectrometer (500 MHz) manufactured by Bruker Biospin under the following measurement conditions: measurement solvent: 1,1,2,2-tetrachloroethane-d2, measurement temperature: 120°C, spectrum width: 20 ppm, pulse repetition time: 7.0 seconds, pulse width: 5.00 μsec (45° pulse). 1 A H-NMR spectrum was obtained. In the obtained spectrum, the graft ratio of the graft polymer obtained in the following synthesis example was calculated from the peak intensity ratio of the proton of the hydrocarbon group bonded to the carbodiimide group present at 3.0 ppm to 4.0 ppm to the peak intensity ratio of the protons bonded to all hydrocarbon groups derived from the base polymer present at 0.3 ppm to 2.5 ppm.

[0090] [Synthesis Example 1] A 500 mL separable flask was charged with 22.5 g of polypropylene (base polymer, Mw: 157,000, Mn: 31,000, Mw / Mn: 5.06) and 62 mL of xylene. The separable flask was then purged with nitrogen, and the internal temperature was raised to 120 ° C. While maintaining that temperature, 44.2 mmol of ethyl methacrylate-tert-butylcarbodiimide was added. Next, 18.4 mmol of tert-butylperoxyisopropyl monocarbonate (Perbutyl I, manufactured by NOF Corporation) dissolved in 10 mL of xylene was added over 10 minutes using a double anchor blade while stirring at a stirring speed of 400 rpm. After stirring for another 3 hours, 100 mL of xylene was added to dilute the reaction solution. The internal temperature of the separable flask was then cooled to 50 ° C., and the slurry-like reaction solution was removed. 400 mL of acetone was added to the resulting reaction solution, and the mixture was stirred for 10 minutes. The stirred solution was then filtered to separate the solids and the filtrate. The process from adding acetone to the resulting solids to filtering was repeated three more times. These four filtrations removed unreacted ethyl methacrylate-tert-butylcarbodiimide and ethyl methacrylate-tert-butylcarbodiimide homopolymers. The solids after the fourth filtration were dried in a vacuum dryer at 90°C for 10 hours to obtain 23.18 g of graft polymer (P-1). The graft ratio was 4.0% by mass.

[0091] Synthesis Example 2: A 500 mL glass vessel was charged with 25.0 g of polypropylene (the same polymer as the base polymer used in Synthesis Example 1) and 110 mL of xylene, and the atmosphere inside the vessel was replaced with nitrogen. The internal temperature of the vessel was then raised to 120°C, and while maintaining that temperature, 33.4 mmol of maleic anhydride was added. Next, 2.2 mmol of tert-butylperoxyisopropyl monocarbonate (Perbutyl I, manufactured by NOF Corporation) dissolved in 10 mL of xylene was added dropwise over 10 minutes while stirring at a stirring speed of 400 rpm using a double anchor impeller. Stirring was then continued for an additional 3 hours. Next, 200 mL of xylene was added, and the internal temperature of the vessel was gradually cooled to 50°C. The slurry-like reaction liquid was then removed, and 400 mL of acetone was added to the resulting reaction liquid and stirred for 10 minutes. The reaction liquid was then filtered to separate the solids and filtrate. The obtained solid was washed three times with 400 mL of acetone to remove unreacted maleic anhydride. The obtained solid was dried in a vacuum dryer at 90°C for 10 hours to obtain 25.01 g of graft polymer (CP-1). The graft rate was 0.62 mass%.

[0092] Example 1 16 parts by mass of the graft polymer (P-1) produced in Synthesis Example 1 and 84 parts by mass of polypropylene (the same polymer as the base polymer used in Synthesis Example 1) were kneaded using a Labo Plastomill at a temperature of 190°C, a screw rotation speed of 60 rpm, and a kneading time of 10 minutes to obtain a battery adhesive C-1. The obtained battery adhesive C-1 had an MFR (230°C, 2.16 kg load) of 3.5 g / 10 min and a density of 0.902 g / cm ３ The amount of carbodiimide groups per 100 g of the resulting battery adhesive C-1 was 3.1 mmol.

[0093] [Example 2] Battery adhesive C-2 was obtained in the same manner as in Example 1, except that the amount of graft polymer (P-1) used was changed to 4 parts by mass and the amount of polypropylene used was changed to 96 parts by mass. The obtained battery adhesive C-2 had a density of 0.903 g / cm ３ The amount of carbodiimide groups per 100 g of the resulting battery adhesive C-2 was 0.8 mmol.

[0094] [Example 3] Battery adhesive C-3 was obtained in the same manner as in Example 1, except that the amount of graft polymer (P-1) used was changed to 8 parts by mass and the amount of polypropylene used was changed to 92 parts by mass. The obtained battery adhesive C-3 had a density of 0.903 g / cm ３ The amount of carbodiimide groups per 100 g of the resulting battery adhesive C-3 was 1.5 mmol.

[0095] [Example 4] Battery adhesive C-4 was obtained in the same manner as in Example 1, except that the amount of graft polymer (P-1) used was changed to 38 parts by mass and the amount of polypropylene used was changed to 62 parts by mass. The obtained battery adhesive C-4 had a density of 0.901 g / cm ３ The amount of carbodiimide groups per 100 g of the resulting battery adhesive C-4 was 7.3 mmol.

[0096] Comparative Example 1 Battery adhesive CC-1 was obtained in the same manner as in Example 1, except that 13 parts by mass of the graft polymer (CP-1) produced in Synthesis Example 2 and 87 parts by mass of polypropylene (the same polymer as the base polymer used in Synthesis Example 1) were used. The obtained battery adhesive CC-1 had an MFR (230°C, 2.16 kg load) of 2.1 g / 10 min and a density of 0.892 g / cm 3 The amount of acid anhydride groups per 100 g of the adhesive was 0.8 mmol, and the adhesive did not contain any graft-modified product with a carbodiimide monomer.

[0097] <Amount of Carbodiimide Groups or Acid Anhydride Groups> The amount (mmol) of carbodiimide groups or acid anhydride groups per 100 g of the battery adhesives obtained in Examples 1 to 4 and Comparative Example 1 was calculated from the following formula (I): (Graft rate [mass %] of graft modified compound used in battery adhesive / molecular weight of carbodiimide monomer or acid anhydride used in synthesizing the graft modified compound) × 100 × amount of graft modified compound used in battery adhesive [mass %] / 10 (I).

[0098] <Density> The density (g / cm 3 ) of the battery adhesives obtained in Examples 1 to 4 and Comparative Example 1 3) was measured in accordance with JIS K 7210.

[0099] <Adhesion Evaluation> - Preparation of Press Sheets Each of the battery adhesives obtained in Examples 1 to 4 and Comparative Example 1 was press-molded under conditions of a temperature of 170°C, a pressure of 4 MPa, a preheating time of 8 minutes, and a pressing time of 3 minutes, and then quenched for 3 minutes in a press molding machine set to 20°C to prepare a press sheet having a thickness of 500 μm, a length of 80 mm, and a width of 80 mm.

[0100] A 100 μm thick, 80 mm long, and 80 mm wide aluminum foil was used as the metal layer. A Teflon® sheet, the aluminum foil, the press sheet, and a Teflon® sheet were stacked in this order, and heat-sealed for 3 seconds at a heat seal pressure of 0.15 MPa using a heat sealer with the lower press plate temperature set to 180° C. and the upper press plate temperature set to 180° C. The Teflon® sheet was then removed to produce a battery laminate consisting of two layers: aluminum foil and a press sheet (adhesive layer).

[0101] Peel test (before immersion in electrolyte solution) Using the prepared battery laminate, the aluminum foil and the press sheet were T-peeled under the conditions of a peeling atmosphere temperature of 23°C, a peeling speed of 300 mm / min, and a peel width of 15 mm, to measure the adhesive strength between the aluminum foil and the press sheet (adhesion strength before immersion in electrolyte solution).

[0102] Peeling test (after immersion in electrolyte solution) The prepared battery laminate was immersed in an electrolyte solution (composition: ethylene carbonate / diethyl carbonate = 3% by volume / 7% by volume, vinylene carbonate content = 0.5% by mass, lithium hexafluorophosphate = 1M, H ２ The battery laminate was immersed in the electrolyte solution (O content = 1000 ppm) for 7 days. After immersion in the electrolyte solution for 7 days, the battery laminate was removed from the electrolyte solution, and the aluminum foil and press sheet in the battery laminate removed from the electrolyte solution were T-peeled together under the following conditions: peeling atmosphere temperature 23°C, peeling speed 300 mm / min, and peel width 15 mm, to measure the adhesive strength between the aluminum foil and press sheet (adhesion strength after immersion in the electrolyte solution). The results are shown in Table 1.

[0103] The presence or absence of an increase in adhesive strength before and after immersion in the electrolyte was evaluated according to the following evaluation criteria. The results are shown in Table 1. ∘: When the adhesive strength before immersion in the electrolyte was taken as 100%, the adhesive strength after immersion in the electrolyte was 130% or more. ×: When the adhesive strength before immersion in the electrolyte was taken as 100%, the adhesive strength after immersion in the electrolyte was less than 100%.

[0104]

[0105] According to one embodiment of the present invention (Example), an adhesive layer with higher adhesive strength was formed after contact with the electrolyte solution compared to before contact with the electrolyte solution. On the other hand, the adhesive strength of the conventional battery adhesive (Comparative Example) decreased after immersion in the electrolyte solution. The decrease in adhesive strength is thought to be caused by the generation of acid in the electrolyte solution. Even when an electrolyte solution other than the one used in the test is used, acid is similarly generated, and therefore, it is thought that the same results as those in Table 1 would be obtained even when an electrolyte solution other than the one used in the test is used.

Claims

1. A battery adhesive satisfying the following requirements (i) to (iii): (i) comprising at least one base polymer selected from polyolefins, graft-modified with at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2); (ii) comprising 0.1 to 50 mmol of carbodiimide groups per 100 g of the battery adhesive; (iii) having a density of 0.870 to 0.940 g / cm ３ is; In formula (1), R １ is a hydrogen atom or a methyl group, R ２ represents an alkyl group or an aryl group which may have a substituent, ３ is a hydrogen atom or a methyl group, R ４ represents an alkyl group or an aryl group which may have a substituent, and m is an integer of 2 or more.

2. The above R ２ The battery adhesive according to claim 1 , wherein is an aliphatic hydrocarbon group having 4 to 20 carbon atoms and including an alicyclic ring.

3. The above R ３ is a methyl group, R ４ 2. The battery adhesive of claim 1 , wherein is a branched and non-cyclic alkyl group and m is 2.

4. The battery adhesive according to claim 1, wherein the base polymer is a polymer that does not have at least one active hydrogen-containing group selected from a carboxy group, an acid anhydride group, an amino group, a hydroxyl group and a thiol group.

5. A battery stack comprising an adhesive layer formed from the battery adhesive of any one of claims 1 to 4 and a metal layer.

6. The battery stack of claim 5, wherein the metal layer is an aluminum layer.

7. A battery packaging material or tab lead comprising the battery stack according to claim 6.

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