Polyolefin adhesive composition

Abstract

To provide an adhesive composition comprising an acid-modified polyolefin and a multifunctional polyisocyanate curing agent, which has good pot life, has good adhesion between a metal base material and a polyolefin resin base material, chemical resistance and moldability.SOLUTION: There is provided an adhesive composition which comprises an acid-modified polyolefin (A), a multifunctional polyisocyanate curing agent (B) and an organic solvent (C), wherein the acid-modified polyolefin (A) is a propylene-α-olefin copolymer grafted with at least one α,β-unsaturated carboxylic acid and its acid anhydride and the organic solvent (C) is a mixed solution of a solvent (C1) which is one or more solvents selected from the group consisting of an aromatic hydrocarbon, an aliphatic hydrocarbon, an alicyclic hydrocarbon and a halogenated hydrocarbon and a solvent (C2) which is one or more solvents selected from the group consisting of an alcohol-based solvent, a ketone-based solvent, an ester-based solvent and a glycol ether-based solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition that exhibits good adhesion, chemical resistance, and moldability between polyolefin resin substrates and metal substrates. More specifically, the present invention relates to an adhesive composition containing an acid-modified polyolefin, a multifunctional polyisocyanate curing agent, and an organic solvent. In particular, the present invention relates to an adhesive composition for lithium ion batteries (hereinafter abbreviated as LiB), and a packaging material that is a laminate containing the same. . [Background technology]

[0002] In recent years, LiBs, which can be made ultra-thin and compact, have been actively developed as batteries for use in personal computers, mobile terminal devices such as mobile phones, video cameras, satellites, etc. Unlike the metal cans that have been used conventionally, the packaging materials for these LiBs have the advantages of being lightweight and allowing for flexible selection of the battery shape, and laminates with a structure such as a base layer / barrier layer / sealant layer have come to be used.

[0003] LiB contains propylene carbonate, ethylene carbonate, The battery contains an electrolyte layer made of an electrolyte solution in which a lithium salt is dissolved in an aprotic solvent such as dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate, or a polymer gel impregnated with the electrolyte solution. If such a highly permeable solvent passes through the sealant layer, it reduces the laminate strength between the barrier layer and the sealant layer, causing delamination and ultimately causing problems such as leakage of the electrolyte. The lithium salt used as the battery electrolyte is LiPF6, However, these salts react with water to generate hydrofluoric acid, which corrodes the barrier layer and reduces the laminate strength. Therefore, battery packaging materials must be resistant to electrolytes.

[0004] LiBs are also designed to withstand harsher conditions, assuming they will be used in a variety of environments. For example, when used in mobile devices, they must be leak-resistant in high-temperature environments of 60 to 70°C, such as inside a car. Also, when used in a mobile phone, they must be water-resistant to prevent water from seeping in if accidentally dropped into water.

[0005] Under these circumstances, various packaging materials for lithium batteries with improved electrolyte resistance have been proposed (see, for example, Patent Documents 1 to 3).

[0006] Furthermore, when a battery packaging material is used to encapsulate a battery element, it is molded using a mold to form a space for accommodating the battery element. During this molding, the battery packaging material is stretched, which can easily cause cracks or pinholes in the barrier layer at the flange of the mold. In particular, with the recent demand for smaller and thinner batteries, thinner battery packaging materials are required, making such problems more likely to occur.

[0007] Under these circumstances, battery packaging materials with improved moldability have been proposed (see, for example, Patent Documents 4 and 5). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-243928 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-42477 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-238475 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-216714 [Patent Document 5] Japanese Patent Application Laid-Open No. 2003-31188 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the above-mentioned proposed packaging materials for lithium batteries are still insufficient in terms of electrolyte resistance and formability, and even if the electrolyte resistance and formability are significantly improved, problems still remain. Specifically, it is difficult to ensure both the pot life of the adhesive after blending the curing agent and electrolyte resistance (Patent Document 1), the lamination machine is limited because bonding is performed by extrusion lamination, and the polyolefin substrate is affected by thermal shrinkage due to lamination at high temperatures (Patent Document 2), and the polyolefin base material is water-based, which requires a long drying time and limits production conditions (Patent Document 3). Furthermore, a process for coating the outer layer film surface with an amide-based slip agent is required, which reduces productivity, and the coated amide-based slip agent does not provide sufficient laminate strength between the outer layer film and the aluminum foil (Patent Document 4). Since only an unstretched polypropylene resin film is arranged on the inner side of the aluminum foil, or only a polypropylene and polyethylene blend resin film is arranged on the inner side of the aluminum foil, pinholes or breaks (cracks) easily occur in the aluminum foil when the film is molded into a rectangular parallelepiped shape, resulting in insufficient moldability (Patent Document 5).

[0010] An object of the present invention is to provide an adhesive composition that is excellent in adhesion, chemical resistance (electrolyte resistance), and moldability without problems such as limited pot life and production conditions, and to provide a battery packaging material that includes an adhesive layer made of the adhesive composition, and a battery that uses the packaging material. [Means for solving the problem]

[0011] In order to achieve the above-mentioned problems, the present inventors have intensively studied and found that it is effective to provide a layer that can sufficiently follow the elongation during molding not only on the outer layer side but also on the inner layer side of the aluminum foil, and have come to propose the following invention.

[0012] An adhesive composition comprising an acid-modified polyolefin (A), a multifunctional polyisocyanate curing agent (B), and an organic solvent (C), wherein the acid-modified polyolefin (A) has an acid value of 2 to 50 mg KOH / g-resin and an acetone extractable component ratio of 0.01 to 2 mass%.

[0013] It is preferable that the composition contains 0.5 to 40 parts by mass of a polyfunctional polyisocyanate curing agent (B) and 80 to 2,000 parts by mass of an organic solvent (C) relative to 100 parts by mass of the acid-modified polyolefin (A). Furthermore, it is preferable that the organic solvent (C) is a mixed liquid of solvent (C1) and solvent (C2), in which solvent (C1) is one or more solvents selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons, solvent (C2) is one or more solvents selected from the group consisting of alcohol-based solvents, ketone-based solvents, ester-based solvents, and glycol ether-based solvents, and the solvent (C1) / solvent (C2) ratio is 50 to 97 / 50 to 3 (mass ratio).

[0014] The adhesive composition is preferably used for bonding a polyolefin resin substrate to a metal substrate.

[0015] A laminate of a polyolefin resin substrate and a metal substrate bonded with the adhesive composition, and a packaging material for lithium ion batteries comprising the laminate as a constituent member. [Effects of the Invention]

[0016] The adhesive composition of the present invention contains an acid-modified polyolefin, a multifunctional polyisocyanate curing agent, and an organic solvent, and can maintain a good pot life without thickening or gelling even when stored for a long period of time. Furthermore, even when the adhesive composition is bonded at a low temperature of 120°C or less, where the thermal shrinkage of the polyolefin substrate is minimal, and when the adhesive composition is aged at a low temperature of 40°C or less, it is possible to achieve good adhesion between the polyolefin resin substrate and the metal substrate, chemical resistance, and moldability.

[0017] According to the present invention, the adhesive layer can be sufficiently cured by the aging step after lamination while maintaining a good pot life, and can exhibit excellent adhesion and chemical resistance. Furthermore, it is possible to obtain an adhesive layer that satisfies the storage modulus and breaking elongation required to exhibit excellent formability. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail.

[0019] <Acid-modified polyolefin (A)> The acid-modified polyolefin (A) used in the present invention is an acid-modified polyolefin having an acid value of 2 to 50 mg KOH / g-resin and an acetone extractable component ratio of 0.01 to 2 mass %.

[0020] The acid-modified polyolefin (A) used in the present invention is not limited, but is preferably one obtained by grafting at least one of polyethylene, polypropylene, and propylene-α-olefin copolymer with at least one of α,β-unsaturated carboxylic acid and its acid anhydride.

[0021] Propylene-α-olefin copolymers are copolymers of propylene as the main component with an α-olefin. As the α-olefin, for example, one or more of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, etc. can be used. Among these α-olefins, ethylene and 1-butene are preferred. The ratio of the propylene component to the α-olefin component in the propylene-α-olefin copolymer is not limited, but the propylene component is preferably 50 mol% or more, and more preferably 70 mol% or more.

[0022] Examples of at least one of α,β-unsaturated carboxylic acids and their acid anhydrides include maleic acid, itaconic acid, citraconic acid, and their acid anhydrides. Among these, acid anhydrides are preferred, and maleic anhydride is more preferred. Specific examples include maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-butene copolymer, and maleic anhydride-modified propylene-ethylene-butene copolymer, and these acid-modified polyolefins can be used alone or in combination of two or more.

[0023] The acid value of the acid-modified polyolefin (A) must be in the range of 2 to 50 mgKOH / g-resin from the viewpoints of adhesion between the polyolefin resin substrate and the metal substrate and electrolyte resistance. It is preferably in the range of 3 to 45 mgKOH / g-resin, more preferably 5 to 40 mgKOH / g-resin, and particularly preferably 7 to 35 mgKOH / g-resin. If the acid value is less than the above range, compatibility with the curing agent may be poor. As a result, the crosslink density may be low, and the adhesive strength and chemical resistance (electrolyte resistance) may be reduced. If the acid value is greater than the above range, the molecular weight may be low and the cohesive force may be weak, which may reduce the adhesive strength and chemical resistance (electrolyte resistance). Furthermore, production efficiency may also be reduced, which is undesirable.

[0024] The acid value of the acid-modified polyolefin (A) can be adjusted by the amounts of the α,β-unsaturated carboxylic acid, the acid anhydride of the α,β-unsaturated carboxylic acid, and the radical generator used.

[0025] The acetone extractable component ratio of the acid-modified polyolefin (A) must be in the range of 0.01% to 2% by mass from the viewpoints of adhesion between the polyolefin resin substrate and the metal substrate and electrolyte resistance. It is preferably 0.03% to 1.7% by mass, more preferably 0.05% to 1.4% by mass, even more preferably 0.07% to 1.2% by mass, and particularly preferably 0.1% to 1% by mass. A ratio below this value is undesirable because it reduces production efficiency. A ratio above this value may weaken the cohesive strength, resulting in poor adhesion, chemical resistance, and moldability.

[0026] The storage modulus (E') of the acid-modified polyolefin (A) at 25°C is From the viewpoint of adhesive strength between the resin substrate and the metal substrate and chemical resistance (electrolyte resistance), the pressure is preferably in the range of 10 to 2000 MPa, more preferably 15 to 1700 MPa, even more preferably 20 to 1400 MPa, particularly preferably 25 to 1100 MPa, and most preferably 30 to 800 MPa. If the pressure is less than the above range, the adhesive comprising the adhesive composition will not be able to adhere. This may lead to insufficient cohesive strength of the adhesive layer, resulting in poor adhesion and chemical resistance (electrolyte resistance). If the value exceeds the above range, the conformability of the adhesive layer made of the adhesive composition may decrease, resulting in poor adhesion. Furthermore, if the value is within the above range, the adhesiveness and conformability to the substrate are improved, which also improves the formability of the laminate, making it more preferable as a packaging material for lithium-ion batteries.

[0027] The tensile elongation at break (Eb) of the acid-modified polyolefin (A) at 25°C is 50% to 100%. It is preferably in the range of 0%. It is more preferably 80% to 900%, even more preferably 120% to 800%, particularly preferably 160% to 700%, and most preferably 200% to 600%. If it is less than the above value, the conformability of the adhesive layer made of the adhesive composition will decrease, which may lead to pinholes during molding and poor moldability. In addition, the tensile breaking elongation (Eb) and the storage modulus (E') are generally contradictory properties, and if they exceed the above value, If the temperature is too high, the storage modulus (E') may decrease, resulting in poor adhesion and electrolyte resistance. Within the above range, the adhesiveness and substrate conformability are improved, and the formability of the laminate is also improved, making it more preferable as a packaging material for lithium ion batteries.

[0028] The weight-average molecular weight (Mw) of the acid-modified polyolefin (A) is preferably in the range of 10,000 to 200,000. It is more preferably in the range of 20,000 to 180,000, even more preferably in the range of 30,000 to 160,000, particularly preferably in the range of 40,000 to 140,000, and most preferably in the range of 50,000 to 110,000. If it is less than the above value, the cohesive strength may be weak, resulting in poor adhesiveness. On the other hand, if it exceeds the above value, the fluidity may be low, resulting in problems with operability during adhesion. A molecular weight within the above range is preferred because it makes the most of the curing reaction with the curing agent.

[0029] The crystallinity of the acid-modified polyolefin (A) can be determined by measuring the crystallinity by heating the polyolefin from -100°C to 250°C at a rate of 20°C / min using a differential scanning calorimeter (DSC). Refers to what is shown.

[0030] By making the acid-modified polyolefin crystalline, it is advantageous to have stronger cohesive strength and superior adhesiveness and chemical resistance compared to amorphous polyolefins.

[0031] The melting point (Tm) of the acid-modified polyolefin (A) is preferably in the range of 50°C to 120°C, more preferably in the range of 60°C to 100°C, and most preferably in the range of 70°C to 90°C. If it is less than the above value, the cohesive force derived from the crystals will be weak, and the adhesiveness and chemical resistance may be poor. On the other hand, if it exceeds the above value, the solution stability and fluidity will be poor, and adhesion may be difficult. This may cause problems with the operation of the device.

[0032] The heat of fusion (ΔH) of the acid-modified polyolefin (A) is preferably in the range of 1 J / g to 60 J / g, more preferably in the range of 3 J / g to 50 J / g, and most preferably in the range of 5 J / g to 40 J / g. If it is less than the above value, the cohesive force derived from the crystals will be weak, and the adhesiveness and chemical resistance may be poor. On the other hand, if it exceeds the above value, the solution stability and fluidity will be low, and problems may arise in the operability during adhesion.

[0033] The method for producing the acid-modified polyolefin (A) is not particularly limited, and examples thereof include a radical graft reaction (i.e., a reaction in which radical species are generated in a polymer that becomes the main chain, and an unsaturated carboxylic acid and an acid anhydride are graft polymerized using the radical species as a polymerization initiation point).

[0034] The radical generator is not particularly limited, but is preferably an organic peroxide.The organic peroxide is not particularly limited, but includes peroxides such as di-tert-butyl peroxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, lauroyl peroxide, etc.; azonitriles such as azobisisobutyronitrile, azobisisopropionitrile, etc.

[0035] <Multifunctional polyisocyanate curing agent (B)> The polyfunctional polyisocyanate curing agent (B) used in the present invention has two or more isocyanates in one molecule. There are no particular limitations on the polyisocyanate as long as it has a cyanate group, and well-known diisocyanates and compounds derived therefrom can be preferably used. Examples of diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, bis(4-isocyanatocyclohexyl)methane, and hydrogenated diphenylmethane diisocyanate. Further examples include compounds derived from the above diisocyanates, i.e., isocyanurates, adducts, biurets, uretdiones, and allophanates of the above diisocyanates, prepolymers having isocyanate residues (low polymers obtained from diisocyanates and polyols), and complexes thereof. These may be used alone or in any combination of two or more.

[0036] Furthermore, a compound obtained by reacting some of the isocyanate groups of the above isocyanate compounds with a compound reactive with the isocyanate groups may be used as a polyfunctional isocyanate curing agent. Examples of compounds reactive with an isocyanate group include compounds containing an amino group, such as butylamine, hexylamine, octylamine, 2-ethylhexylamine, dibutylamine, ethylenediamine, benzylamine, and aniline; compounds containing a hydroxyl group, such as methanol, ethanol, propanol, isopropanol, butanol, hexanol, octanol, 2-ethylhexyl alcohol, dodecyl alcohol, ethylene glycol, propylene glycol, benzyl alcohol, and phenol; compounds containing an epoxy group, such as allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether; and compounds containing a carboxylic acid, such as acetic acid, butanoic acid, hexanoic acid, octanoic acid, succinic acid, adipic acid, sebacic acid, and phthalic acid.

[0037] As the polyfunctional polyisocyanate curing agent (B) used in the present invention, those having an isocyanurate of the above diisocyanate are preferred because they have excellent electrolyte resistance.

[0038] The amount of the polyfunctional polyisocyanate curing agent (B) used in the present invention is preferably in the range of 0.5 to 40 parts by mass relative to 100 parts by mass of the acid-modified polyolefin (A), more preferably Preferably, it is 1 to 35 parts by mass, more preferably 2 to 30 parts by mass, and particularly preferably 3 to 25 parts by mass. If it is less than the above value, a sufficient curing effect may not be obtained, and adhesion and chemical resistance may be low. If it exceeds the above range, pot life and adhesion may decrease, and pinholes may occur during molding due to reduced conformability. Furthermore, it is not preferable from the viewpoint of cost.

[0039] <Organic solvent (C)> The organic solvent (C) used in the present invention is not particularly limited as long as it can dissolve the acid-modified polyolefin (A) and the polyfunctional polyisocyanate curing agent (B). Specific examples include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane; halogenated hydrocarbons such as trichloroethylene, dichloroethylene, chlorobenzene, and chloroform; alcoholic solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol; and ketones such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, and acetophenone. Cellosolves such as methyl cellosolve and ethyl cellosolve; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate and butyl formate; glycol ether solvents such as ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether, and the like can be used alone or in combination of two or more thereof.

[0040] The organic solvent (C) is preferably in the range of 80 to 2000 parts by mass relative to 100 parts by mass of the acid-modified polyolefin (A), more preferably 90 to 1600 parts by mass, even more preferably 100 to 1200 parts by mass, and particularly preferably 110 to 800 parts by mass. If the amount is less than this range, the solution state and pot life may be reduced, while if the amount is more than this range, the productivity, production costs, and transportation costs of the laminate and the LiB packaging material containing the laminate may be reduced. This may be disadvantageous in terms of cost.

[0041] From the viewpoint of the solution state and pot life of the adhesive composition, the organic solvent (C) is preferably a mixture of one or more solvents (C1) selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons, and one or more solvents (C2) selected from the group consisting of alcohol solvents, ketone solvents, ester solvents, and glycol ether solvents. The mixing ratio of solvent (C1) / solvent (C2) is preferably in the range of 50-97 / 50-3 (mass ratio), more preferably 55-95 / 45-5 (mass ratio), even more preferably 60-90 / 40-10 (mass ratio), and particularly preferably 70-80 / 30-20 (mass ratio). Outside this range, the solution state and pot life of the adhesive composition may be deteriorated. Furthermore, it is particularly preferred that solvent (C1) is an aromatic hydrocarbon or alicyclic hydrocarbon, and solvent (C2) is a ketone solvent.

[0042] <Adhesive composition> The adhesive composition of the present invention is a mixture of the acid-modified polyolefin (A), a polyfunctional polyisocyanate curing agent (B), and an organic solvent (C), and the acid-modified polyolefin (A) and the curing agent (B) may be dissolved or dispersed in the organic solvent (C). From the viewpoint of pot life, they are preferably dissolved.

[0043] The adhesive composition of the present invention may contain various tackifiers, thermoplastic elastomers, and plasticizers in addition to the acid-modified polyolefin (A), polyfunctional polyisocyanate curing agent (B), and organic solvent (C), as long as the properties of the present invention are not impaired. Examples of tackifiers include, but are not limited to, polyterpene resins, rosin resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymer petroleum resins, and hydrogenated petroleum resins. Examples of thermoplastic elastomers include styrene-based elastomers such as styrene-ethylene-butylene-styrene copolymer resins and styrene-ethylene-propylene-styrene, as well as olefin-based elastomers such as ethylene-propylene copolymer resins, ethylene-butene copolymer resins, ethylene-vinyl acetate copolymer resins, and ethylene-ethyl acrylate copolymer resins. Examples of plasticizers include liquid rubbers such as polyisoprene and polybutene, and process oils. These tackifiers, thermoplastic elastomers, and plasticizers may be used alone or in combination.

[0044] In addition to the acid-modified polyolefin (A), the polyfunctional polyisocyanate curing agent (B), and the organic solvent (C), various curing agents can be used in the adhesive composition of the present invention, as long as the performance of the present invention is not impaired. Examples of curing agents include, but are not limited to, epoxy resins, carbodiimide compounds, oxazoline compounds, and coupling agents. Examples of epoxy resins include glycidyl ester types such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester, alicyclic or aliphatic epoxides such as triglycidyl isocyanurate, 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil, glycidyl ether-type epoxy resins, and glycidyl amine-type epoxy resins. Examples of the carbodiimide compound include monocarbodiimide compounds such as dimethylcarbodiimide, diisopropylcarbodiimide, dicyclohexylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, and di-β-naphthylcarbodiimide, and polycarbodiimide compounds that can be produced by carrying out a decarboxylation condensation reaction of an organic diisocyanate such as an aliphatic diisocyanate, an aromatic diisocyanate, or an alicyclic diisocyanate in the presence of a condensation catalyst, in the absence of a solvent or in an inert solvent. Examples of oxazoline compounds include monooxazoline compounds such as 2-oxazoline, 2-methyl-2-oxazoline, 2-phenyl-2-oxazoline, 2,5-dimethyl-2-oxazoline, and 2,4-diphenyl-2-oxazoline, and dioxazoline compounds such as 2,2'-(1,3-phenylene)-bis(2-oxazoline), 2,2'-(1,2-ethylene)-bis(2-oxazoline), 2,2'-(1,4-butylene)-bis(2-oxazoline), and 2,2'-(1,4-phenylene)-bis(2-oxazoline). Examples of coupling agents include silane coupling agents and titanate coupling agents.

[0045] The adhesive composition of the present invention can be used by blending a curing accelerator in addition to the acid-modified polyolefin (A), the polyfunctional polyisocyanate curing agent (B), and the organic solvent (C), as long as the performance of the present invention is not impaired. The curing accelerator is not particularly limited, but examples thereof include metal carboxylates, tertiary amines, quaternary ammonium salts, organic peroxides, hydrazine compounds, metal chelate compounds, phosphorus-containing compounds, and basic vulcanizing agents. Examples of the metal carboxylates include metal salts of carboxylic acids having 1 to 30 carbon atoms. The carboxylic acids Examples of carboxylic acids that can be used to form acid metal salts include aliphatic carboxylic acids such as acetic acid, butyric acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid, octenoic acid, erucic acid, elaidic acid, adipic acid, malonic acid, succinic acid, glutaric acid, citric acid, tartaric acid, malic acid, and diglycolic acid; aromatic carboxylic acids such as benzoic acid, chlorobenzoic acid, anisic acid, aminobenzoic acid, phthalic acid, terephthalic acid, naphthoic acid, naphthalenedicarboxylic acid, and benzenetricarboxylic acid; naphthenic acid; and acetone acid. Examples of metals constituting the carboxylic acid metal salt include Li, Na, K, Mg, Ca, Zn, Al, Cu, Pb, Co, Fe, Mn, Sn, and Ti. Specific examples of the carboxylic acid metal salt include lithium acetate, sodium acetate, magnesium acetate, aluminum acetate, potassium butyrate, calcium butyrate, zinc butyrate, sodium octanoate, calcium octanoate, potassium decanoate, magnesium decanoate, zinc decanoate, lithium laurate, sodium laurate, calcium laurate, aluminum laurate, potassium myristate, sodium myristate, aluminum myristate, sodium palmitate, zinc palmitate, magnesium palmitate, sodium stearate, potassium stearate, calcium stearate, and stearic acid. Examples of the surfactants include zinc, sodium oleate, sodium behenate, sodium benzoate, zinc benzoate, sodium phthalate, aluminum phthalate, magnesium terephthalate, calcium naphthalenedicarboxylate, dibutyltin laurate, tributyltin laurate, dioctyltin laurate, tributyltin acetate, dibutyltin diacetate, dioctyltin diacetate, dibutyltin 2-ethylhexoate, tetrabutyl titanate, tetraisobutyl titanate, tetra 2-ethylhexyl titanate, cobalt naphthenate, copper naphthenate, magnesium naphthenate, and cobalt acetoacetate. Among these, preferred are lithium laurate, sodium laurate, calcium laurate, aluminum laurate, potassium myristate, sodium myristate, aluminum myristate, sodium palmitate, zinc palmitate, magnesium palmitate, sodium stearate, potassium stearate, calcium stearate, zinc stearate, and sodium oleate. Furthermore, as the metal salt of carboxylic acid, a polymer having a metal salt structure of carboxylic acid can also be used.Examples of such polymers include those having a structure obtained by copolymerizing ethylene with a radically polymerizable carboxylic acid salt of a metal of Group IA, Group IIA, Group IIB, or Group IIIB (e.g., Li, Na, K, Mg, Ca, Zn, Al, etc.); and those having a structure obtained by multi-component copolymerization of ethylene with a metal salt of a radically polymerizable carboxylic acid and another radically polymerizable carboxylic acid and / or its derivative. Examples of the tertiary amines include dimethylaniline, triethanolamine, and dimethyl-p-toluidine. Examples of the hydrazine compounds include 1-acetyl-2-phenylhydrazine. Examples of the metal chelate compounds include vanadium acetylacetonate. Examples of the phosphorus-containing compounds include dimethylphosphine and triphenylphosphine. Examples of the basic vulcanizing agents include hexamethylenetetramine and n-butylaldehyde-aniline condensates.

[0046] The adhesive composition of the present invention may contain various other components in addition to the acid-modified polyolefin (A), the polyfunctional polyisocyanate curing agent (B), and the organic solvent (C) within the range that does not impair the performance of the present invention. The additives are not particularly limited, but it is preferable to use a flame retardant, a pigment, an anti-blocking agent, etc.

[0047] <Laminate> The laminate of the present invention is obtained by laminating a polyolefin resin substrate and a metal substrate with the adhesive composition of the present invention.

[0048] As a lamination method, a conventionally known laminate manufacturing technique can be used. For example, although not particularly limited, the adhesive composition is applied to the surface of a metal substrate using a suitable application means such as a roll coater or a bar coater, and then dried. After drying, while the layer of the adhesive composition (adhesive layer) formed on the surface of the metal substrate is in a molten state, a polyolefin resin substrate can be laminated (laminated) to the applied surface to obtain a laminate. The thickness of the adhesive layer formed from the adhesive composition is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.8 to 9.5 μm, and even more preferably 1 to 9 μm.

[0049] <Polyolefin resin substrate> The polyolefin resin substrate may be appropriately selected from conventionally known polyolefin resins. For example, polyethylene, polypropylene, ethylene-propylene copolymer, etc. can be used, but are not particularly limited thereto. Among these, the use of a non-oriented polypropylene film (hereinafter also referred to as CPP) is preferred. Its thickness is not particularly limited, but is preferably 20 to 100 μm, more preferably 25 to 95 μm, and even more preferably 30 to 90 μm. The polyolefin resin substrate may be blended with pigments or various additives, or may be surface-treated, as necessary.

[0050] <Metal base material> The metal substrate is not particularly limited, and various metals and alloys thereof, such as aluminum, copper, steel, chromium, zinc, duralumin, and die-cast metals, can be used. The substrate can take any shape, such as metal foil, rolled steel plate, panel, pipe, can, or cap. Generally, aluminum foil is preferred from the viewpoint of workability. Although the thickness varies depending on the intended use, it is generally used in the form of a sheet having a thickness of 0.01 to 10 mm, preferably 0.02 to 5 mm. The surfaces of these metal substrates may be either previously surface-treated or left untreated, with the same effects being achieved in either case.

[0051] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. In the examples and comparative examples, parts simply refer to parts by mass.

[0052] <Production Example of Acid-Modified Polyolefin (A)> Manufacturing Example 1 In a 1-liter autoclave, 100 parts by mass of propylene-ethylene copolymer (storage modulus at 25°C: 320 MPa, tensile elongation at break: 760%) and 233 parts by mass of toluene were added. 1 part by mass of maleic anhydride and 0.5 parts by mass of di-tert-butyl peroxide were added, and the mixture was heated to 140°C and then stirred for another hour (this is referred to as a 1-hour "reaction"). The resulting reaction solution was then cooled to 100°C and poured into a container containing 717 parts by mass of toluene and 950 parts by mass of methyl ethyl ketone, which had been preheated to 40°C, with stirring. The mixture was then cooled to 40°C, stirred for another 30 minutes, and further cooled to 25°C to precipitate a resin (here, the process of pouring the reaction solution into a solvent such as methyl ethyl ketone with stirring and cooling to precipitate a resin is referred to as "reprecipitation"). The resin-containing slurry was then centrifuged to separate the acid-modified propylene-ethylene copolymer graft-polymerized with maleic anhydride, (poly)maleic anhydride, and low-molecular-weight substances. Furthermore, the acid-modified propylene-ethylene copolymer removed by centrifugation was poured into a container containing 2,000 parts by mass of methyl ethyl ketone, which had been previously kept at 25°C, while stirring, and the mixture was stirred for 1 hour. The slurry was then centrifuged to further separate the acid-modified propylene-ethylene copolymer from the (poly)maleic anhydride and low-molecular-weight substances. This procedure was repeated twice for purification (here, the procedure of pouring the acid-modified propylene-ethylene copolymer removed by centrifugation into methyl ethyl ketone while stirring, and then centrifuging again to enhance purification, is referred to as "reslurry"). After purification, the resin was dried under reduced pressure at 70°C for 5 hours to obtain an acid-modified polyolefin, maleic anhydride-modified propylene-ethylene copolymer (PO-1, acid value 2 mg KOH / g-resin, acetone extractable component ratio 0.1 mass%, storage modulus at 25°C 300 MPa, 25°C storage modulus 300 MPa). The tensile elongation at break was 600%, the weight average molecular weight was 190,000, Tm was 88°C, and ΔH was 37 J / g.

[0053] Manufacturing Example 2 The same procedure as in Production Example 1 was carried out except that the amount of maleic anhydride added was changed to 3 parts by mass, the number of reslurries was changed to 1, and the amount of methyl ethyl ketone added during reslurrying was changed to 1,000 parts by mass. An acid-modified polyolefin, maleic anhydride-modified propylene-ethylene copolymer (PO-2, acid value 5 mg KOH / g-resin, acetone extractable component ratio 1.8 mass%, storage modulus at 25°C 280 MPa, tensile break elongation at 25°C 650%, weight The average molecular weight was 180,000, Tm 88°C, ΔH 36 J / g).

[0054] Manufacturing Example 3 The same procedure as in Production Example 1 was repeated except that the amount of toluene charged was 150 parts by mass, the amount of maleic anhydride charged was 40 parts by mass, the amount of di-tert-butyl peroxide charged was 8 parts by mass, the reaction time was 3 hours, the solvent used for reprecipitation was 700 parts by mass of methyl ethyl ketone, and the number of reslurries was 5. An acid-modified polyolefin, maleic anhydride-modified propylene-ethylene copolymer (PO-3, acid value 48 mg KOH / g-resin, acetone extractable component ratio 0.1 mass%, storage modulus at 25°C 180 MPa, tensile break elongation at 25°C 35 The polymer was obtained with a polymerizable copolymer of 100% propylene glycol, ...

[0055] Production Example 4 The same procedure as in Production Example 1 was repeated except that the amount of toluene charged was 150 parts by mass, the amount of maleic anhydride charged was 40 parts by mass, the amount of di-tert-butyl peroxide charged was 8 parts by mass, the reaction time was 3 hours, the solvent used for reprecipitation was 700 parts by mass of methyl ethyl ketone, the solvent used for reslurry was 1000 parts by mass of methyl ethyl ketone, and the number of reslurries was 3. The acid-modified polyolefin maleic anhydride-modified propylene-ethylene copolymer (PO-4, acid value 48 mg KOH / g-resin, acetone extractable component ratio 1.8 mass%, storage modulus at 25°C 150 MPa, tensile break elongation at 25°C 300%, weight-average molecular weight 2 7,000, Tm85℃, △H30J / g).

[0056] Manufacturing Example 5 The same procedure as in Production Example 1 was repeated except that the amount of toluene charged was 150 parts by mass, the amount of maleic anhydride charged was 20 parts by mass, the amount of di-tert-butyl peroxide charged was 6 parts by mass, the reaction time was 3 hours, the solvent used for reprecipitation was 700 parts by mass of methyl ethyl ketone, the solvent used for reslurry was 1000 parts by mass of methyl ethyl ketone, and the number of reslurries was 2. The acid-modified polyolefin maleic anhydride-modified propylene-ethylene copolymer (PO-5, acid value 25 mg KOH / g-resin, acetone extractable component ratio 0.9 mass%, storage modulus at 25°C 400 MPa, tensile elongation at break 500% at 25°C, weight-average molecular weight 6 0,000, Tm87℃, △H35J / g).

[0057] Manufacturing Example 6 Propylene-ethylene copolymer (storage modulus at 25°C: 52 MPa, The same procedure as in Production Example 1 was repeated except that the tensile elongation at break (1050%) was 100 parts by mass, the amount of toluene charged was 150 parts by mass, the amount of maleic anhydride charged was 30 parts by mass, the amount of di-tert-butyl peroxide charged was 6 parts by mass, the reaction time was 3 hours, the solvent used for reprecipitation was 700 parts by mass of methyl ethyl ketone, the solvent used for reslurry was 1000 parts by mass of methyl ethyl ketone, and the number of reslurries was 2. Acid-modified propylene-ethylene copolymer (PO-6, acid value 25 mg KOH / g-resin, acetone extractable component ratio 1.0 mass%, storage modulus at 25°C 12 MPa, tension at 25°C The polymer had a tensile breaking elongation of 900%, a weight average molecular weight of 60,000, a Tm of 58°C, and a ΔH of 7 J / g.

[0058] Manufacturing Example 7 Propylene homopolymer (storage modulus at 25°C: 2100 MPa, tensile strength at 25°C: The same procedure as in Production Example 1 was repeated except that the mixture was changed to 100 parts by mass of toluene, 150 parts by mass of maleic anhydride, 30 parts by mass of di-tert-butyl peroxide, 3 parts by mass of di-tert-butyl peroxide, 3 hours of reaction time, 700 parts by mass of methyl ethyl ketone as the solvent used for reprecipitation, 1000 parts by mass of methyl ethyl ketone as the solvent used for reslurrying, and 2 times of reslurrying, to obtain a maleic anhydride-modified propylene homopolymer (PO-7, acid value 25 mg KOH / g-resin, acetone extractable component ratio 0.9 mass%, storage modulus at 25°C 1800 MPa, tensile elongation at break 900°C). The polymer was obtained with a polymer yield of 60%, weight average molecular weight of 60,000, Tm of 85°C, and ΔH of 5 J / g.

[0059] Manufacturing Example 8 Propylene-ethylene copolymer (storage modulus at 25°C: 2720 MPa, The same procedure as in Production Example 1 was repeated except that the mixture was changed to 100 parts by mass of 100% propylene glycol ether (PPG), 186 parts by mass of toluene, 20 parts by mass of maleic anhydride, 6 parts by mass of di-tert-butyl peroxide, the reaction time was 3 hours, the solvent used for reprecipitation was 700 parts by mass of methyl ethyl ketone, the solvent used for reslurry was 1000 parts by mass of methyl ethyl ketone, and the number of reslurries was two, to obtain a maleic anhydride-modified propylene-ethylene copolymer (PO-8, acid value 25 mg KOH / g-resin, acetone extractable component ratio 1.0 mass%, storage modulus at 25°C 2350 MPa, storage modulus at 25°C 2350 MPa). The tensile elongation at break was 38%, weight average molecular weight was 60,000, Tm was 125°C, and ΔH was 63 J / g.

[0060] Manufacturing Example 9 The same procedure as in Production Example 1 was repeated except that the amount of toluene charged was 186 parts by mass, the amount of maleic anhydride charged was 20 parts by mass, the amount of di-tert-butyl peroxide charged was 6 parts by mass, the reaction time was 3 hours, the solvent used for reprecipitation was 1200 parts by mass of methyl ethyl ketone, the solvent used for reslurry was 1200 parts by mass of methyl ethyl ketone, and the number of reslurries was 2. An acid-modified polyolefin, maleic anhydride-modified propylene-ethylene copolymer (PO-9, acid value 25 mg KOH / g-resin, acetone extractable component ratio 1.2 mass%, storage modulus at 25°C 7 MPa, tensile break elongation at 25°C 1200%, weight average molecular weight 6 0,000, no Tm peak, △H0J / g) was obtained.

[0061] Manufacturing Example 10 Propylene-ethylene copolymer (storage modulus at 25°C: 500 MPa, The same procedure as in Production Example 1 was repeated except that the mixture was changed to 100 parts by mass of 1,000 parts by mass of toluene, 0.5 parts by mass of maleic anhydride, 0.2 parts by mass of di-tert-butyl peroxide, 100 parts by mass of methyl ethyl ketone as the solvent for reprecipitation, 1,000 parts by mass of methyl ethyl ketone as the solvent for reslurrying, and the number of reslurries was changed to two, to obtain a maleic anhydride-modified propylene-ethylene copolymer (PO-10, acid value 1 mg KOH / g-resin, acetone extractable component ratio 0.1 mass%, storage modulus at 25°C 400 MPa, storage modulus at 25°C 400 MPa, storage modulus at 25°C 400 MPa). The tensile elongation at break was 600%, the weight average molecular weight was 65,000, Tm was 71°C, and ΔH was 35 J / g.

[0062] Manufacturing Example 11 The same procedure as in Production Example 1 was repeated except that the amount of toluene charged was 150 parts by mass, the amount of maleic anhydride charged was 50 parts by mass, the amount of di-tert-butyl peroxide charged was 10 parts by mass, the reaction time was 3 hours, the solvent used for reprecipitation was 700 parts by mass of methyl ethyl ketone, the solvent used for reslurry was 1,000 parts by mass of methyl ethyl ketone, and the number of reslurries was 3. An acid-modified polyolefin, maleic anhydride-modified propylene-ethylene copolymer (PO-11, acid value 55 mg KOH / g-resin, acetone extractable component ratio 1.0 mass%, storage modulus at 25°C 150 MPa, tensile elongation at break 320% at 25°C, weight average molecular weight 1000). The obtained product was 30,000, Tm 83°C, ΔH 25 J / g.

[0063] Manufacturing Example 12 The same procedure as in Production Example 1 was repeated except that the amount of toluene charged was 150 parts by mass, the amount of maleic anhydride charged was 40 parts by mass, the amount of di-tert-butyl peroxide charged was 8 parts by mass, the reaction time was 3 hours, and the number of reslurries was 3 times. An acid-modified polyolefin, maleic anhydride-modified propylene-ethylene copolymer (PO-12, acid value 46 mg KOH / g-resin, acetone extractable component ratio 4.5 mass%, storage modulus at 25 ° C. 110 MPa, The tensile elongation at break at 25°C was 90%, the weight average molecular weight was 35,000, Tm was 86°C, and ΔH was 30 J / g.

[0064] (Preparation of main agent 1) A 500 ml four-neck flask equipped with a water-cooled reflux condenser and a stirrer was charged with 100 parts by mass of the maleic anhydride-modified propylene-ethylene copolymer (PO-1) obtained in Production Example 1, 280 parts by mass of methylcyclohexane, and 120 parts by mass of methyl ethyl ketone, and the mixture was heated to 80°C with stirring. Stirring was continued for 1 hour, and then the mixture was cooled to obtain main component 1. The state of the solution is shown in Table 1.

[0065] (Preparation of main agents 2 to 19) Main agents 2 to 19 were prepared in the same manner as main agent 1, except that the acid-modified polyolefin and organic solvent were changed as shown in Table 1. The blend amounts and solution states are shown in Table 1.

[0066] [Table 1]

[0067] Example 1 500 parts by mass of the main agent 1, Sumidur ( 1 part by mass of N-3300 was added to obtain an adhesive composition. The evaluation results for toughness, chemical resistance and moldability are shown in Table 2.

[0068] Examples 2 to 21, Comparative Examples 1 to 3 The base compounds 1 to 19 and the curing agents were changed as shown in Tables 2 and 3, and Examples 2 to 21 and Comparative Examples 1 to 3 were carried out in the same manner as in Example 1. The results of the blending amounts, pot life, adhesion, chemical resistance, and moldability are shown in Tables 2 and 3.

[0069] [Table 2]

[0070] [Table 3]

[0071] The curing agents used in Tables 2 and 3 are as follows: <Multifunctional polyisocyanate curing agent (B)> Isocyanurate of hexamethylene diisocyanate: Sumidur (registered trademark) N -3300 (manufactured by Bayer) Biuret form of hexamethylene diisocyanate: Duranate (registered trademark) 24A-100 (manufactured by Asahi Kasei Chemicals Corporation)

[0072] The acid-modified polyolefins, base resins, and adhesive compositions obtained as described above were subjected to analytical measurements and evaluations according to the following methods. Acid number measurement The acid value (mgKOH / g-resin) in the present invention is the ratio of 1 g of acid-modified polyolefin This refers to the amount of KOH required to neutralize (A), and was measured in accordance with the test method of JIS K0070 (1992). Specifically, 1 g of acid-modified polyolefin was dissolved in 100 g of xylene adjusted to a temperature of 100°C, and then titrated at the same temperature with a 0.1 mol / L potassium hydroxide ethanol solution (trade name "0.1 mol / L ethanolic potassium hydroxide solution," manufactured by Wako Pure Chemical Industries, Ltd.) using phenolphthalein as an indicator. The amount of potassium hydroxide required for the titration was converted to mg to calculate the acid value (mgKOH / g).

[0073] Measurement of acetone extractable component ratio The acetone extractable component ratio in the present invention was measured by refluxing with acetone for 2 hours using a Soxhlet extractor. Specifically, 50 g of acid-modified polyolefin (A) was weighed into a cylindrical filter paper and placed in a Soxhlet extraction tube. After that, a flat-bottomed flask containing 1100 mL of acetone and a condenser were attached and assembled, and the mixture was refluxed in a water bath for 2 hours to perform acetone extraction. Thereafter, the cylindrical filter paper was removed, the acetone extract in the flat-bottomed flask was distilled off, and the residue was further dried under reduced pressure at 100°C for 1 hour. The weight of the residue was measured, and the value was calculated using the following formula. Acetone extractable component ratio (mass%) = (extracted residue weight / sample amount) × 100

[0074] Measurement of storage modulus (E') at 25°C The storage modulus (E') in the present invention is determined by the test method of JIS K7244-4 (1999). Specifically, the values ​​were measured using a dynamic viscoelasticity measuring device DVA-200 manufactured by IT Measurement & Control Co., Ltd., at a frequency of 10 Hz while increasing the temperature from -50°C at a rate of 5°C / min. is.

[0075] Measurement of tensile elongation at break (Eb) at 25°C The tensile elongation at break (Eb) in the present invention was measured in accordance with the test method of JIS K7161 (2014). Specifically, it is the value measured as the elongation (%) at break when tensile at a rate of 50 mm / min in an environment of 25°C using a Tensilon RTM-100 manufactured by Orientec Corporation.

[0076] Measurement of weight average molecular weight (Mw) The weight average molecular weight in the present invention was measured using a gel permeation chromatograph Alliance e2695 (hereinafter referred to as GPC, standard substance: polystyrene resin, transfer Mobile phase: tetrahydrofuran, column: Shodex KF-806 + KF-803, column temperature: 40°C, flow rate: 1.0 ml / min, detector: photodiode array detector (wavelength 254 nm = ultraviolet) Therefore, it is a measured value.

[0077] Melting point and heat of fusion measurement The melting point and heat of fusion in the present invention are values ​​measured using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000) from the top temperature and area of ​​the melting peak when the sample is heated to melt at a rate of 20°C / min, cooled to form a resin, and then heated to melt again.

[0078] Evaluation of the main solution state The solution state of main components 1 to 19 was evaluated by measuring the solution viscosity at 25° C. using a Brookfield viscometer TVB-10M (hereinafter also referred to as a B-type viscometer) manufactured by Toki Sangyo Co., Ltd. <Evaluation criteria> ◎ (Excellent for practical use): Less than 500 mPa·s ○ (practical): 500 mPa·s or more and less than 1000 mPa·s × (Not practical): Viscosity measurement is impossible due to 1000 mPa·s or more or gelation

[0079] Pot life evaluation Pot life refers to the stability of a solution obtained by blending a crosslinking agent or curing agent into an acid-modified polyolefin, either immediately after blending or after a certain period of time has passed since blending. A good pot life means that the viscosity of the solution increases little and it can be stored for a long period of time, while a bad pot life means that the viscosity of the solution increases (thickens), and in severe cases, it may gel, making it difficult to apply to a substrate and making it impossible to store for a long period of time. The pot life of the adhesive compositions obtained in Examples 1 to 21 and Comparative Examples 1 to 3 was evaluated by measuring the solution viscosity at 25°C using a Brookfield viscometer after storing them in an atmosphere at 25°C and 40°C for 24 hours. The evaluation results are shown in Tables 2 and 3. <Evaluation criteria> ◎ (Excellent for practical use): Less than 500 mPa·s ○ (practical): 500 mPa·s or more and less than 1000 mPa·s × (Not practical): Viscosity measurement is impossible due to 1000 mPa·s or more or gelation

[0080] Preparation of a laminate of a metal substrate and a polyolefin resin substrate The metal substrate was aluminum foil (manufactured by Sumikei Aluminum Foil Co., Ltd., 8079-0, thickness 40 μm), and the polyolefin resin substrate was unstretched polypropylene film (manufactured by Toyobo Co., Ltd., Pylen (registered trademark) Film CT, thickness 40 μm) (hereinafter also referred to as CPP). The adhesive compositions obtained in Examples 1 to 19 and Comparative Examples 1 to 15 were applied to metal substrates using a bar coater, adjusting the thickness of the adhesive layer after drying to 3 μm. The coated surface was dried for 1 minute in a 100°C atmosphere using a hot air dryer, yielding a metal substrate laminated with a 3 μm-thick adhesive layer. A polyolefin resin substrate was placed on the surface of the adhesive layer, and the laminate was then laminated using a small desktop test laminator (SA-1010-S) manufactured by Tester Sangyo Co., Ltd. at a lamination temperature of 80°C or 120°C, 0.3 MPa, and 1 m / min. The laminate was then aged for 36 hours at 25°C and 50% RH to obtain a laminate.

[0081] The laminate obtained as described above was evaluated by the following methods.

[0082] Adhesion evaluation The laminate was cut into a size of 100 mm × 15 mm, and the adhesiveness was evaluated according to the following criteria by a T-peel test. The evaluation results are shown in Tables 2 to 3.

[0083] <T-peel test> Based on the test method of ASTM-D1876-61, using a tensilon RTM-100 manufactured by Orientec Corporation, the peel strength at a tensile speed of 50 mm / min was measured at 25°C. The peel strength (N / cm) between the metal substrate and the polyolefin resin substrate was taken as the average value of five test values.

[0084] <Evaluation criteria> ☆(Particularly excellent in practical use): 8.0 N / cm or more, or the CPP breaks (hereinafter, also simply referred to as "material break"). Material break means that peeling does not occur at the interface between the metal substrate and the CPP, and the metal substrate or the CPP is broken. ◎(Excellent in practical use): 7.5 N / cm or more and less than 8.0 N / cm ○(Practicable): 7.0 N / cm or more and less than 7.5 N / cm ×(Impracticable): Less than 7.0 N / cm

[0085] Chemical resistance evaluation To examine the usability as a packaging material for LiB, the chemical resistance (hereinafter, also referred to as electrolyte resistance) was evaluated by an electrolytic solution test. The laminate was cut into a size of 100 mm × 15 mm and immersed in an electrolytic solution [ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1 / 1 / 1 (volume ratio) added with lithium hexafluorophosphate] at 85°C for 1 day. Then, the laminate was taken out, washed with ion-exchanged water, wiped with a paper wiper to remove water, and sufficiently dried, and the chemical resistance was evaluated according to the following criteria by a T-peel test. The evaluation results are shown in Tables 2 to 3.

[0086] <Evaluation criteria> ☆(Particularly excellent in practical use): 8.0 N / cm or more, or material break ◎ (Excellent for practical use): 7.5N / cm or more and less than 8.0N / cm ○ (practical): 7.0N / cm or more and less than 7.5N / cm × (Not practical): Less than 7.0N / cm

[0087] Formability evaluation Similarly, to examine the usability of LiB as packaging material, we evaluated the formability using a deep drawing tester. went. The laminate was cut into a size of 80 x 120 mm and cold-formed. Using an Amada Corporation stretch forming machine (product number: TP-25C-X2), a forming die (female die) with a 55 mm x 35 mm aperture, and a corresponding forming die (male die), cold forming was performed on 10 samples (laminates) at 25°C and a pressure of 0.4 MPa, varying the forming depth in 0.5 mm increments from 0.5 mm. The maximum forming depth at which no wrinkles, pinholes in the aluminum foil, or cracks occurred in any of the 10 cold-formed samples was determined as the limit forming depth for that sample. The formability of the battery packaging material was evaluated based on this limit forming depth according to the following criteria. The evaluation results are shown in Tables 3 and 4. <Judgment criteria> ☆ (Especially excellent for practical use): Limit molding depth 6.0 mm or more ◎ (Excellent for practical use): Limit forming depth 4.0 mm or more and less than 6.0 mm ○ (Practical): Limit forming depth 2.0 mm or more and less than 4.0 mm ×: Limit forming depth less than 2.0 mm [Industrial Applicability]

[0088] The adhesive composition of the present invention contains an acid-modified polyolefin, a multifunctional polyisocyanate curing agent, and an organic solvent, and maintains a good pot life without thickening or gelling even after long-term storage, while achieving good adhesion between a metal substrate and a polyolefin resin substrate, electrolyte resistance, and moldability. Therefore, laminates of a polyolefin resin substrate and a metal substrate formed from the adhesive composition of the present invention can be widely used not only in fields such as outer panels of home appliances, furniture materials, and building interior components, but also as packaging materials (in the form of pouches) for lithium batteries used in personal computers, mobile phones, video cameras, etc.

Claims

1. An adhesive composition consisting essentially of an acid-modified polyolefin (A), a polyfunctional polyisocyanate curing agent (B), and an organic solvent (C), the acid-modified polyolefin (A) is a maleic anhydride-modified propylene-ethylene copolymer, The composition contains 1 to 38 parts by mass of a polyfunctional polyisocyanate curing agent (B) and 100 to 800 parts by mass of an organic solvent (C) relative to 100 parts by mass of the acid-modified polyolefin (A), the acid-modified polyolefin (A) has an acid value of 2 to 50 mg KOH / g-resin and an acetone extractable component ratio of 0.01 to 2 mass%, The storage modulus (E') of the acid-modified polyolefin (A) at 25°C is 180 to 400 MPa, the tensile elongation at break (Eb) of the acid-modified polyolefin (A) at 25°C is 350 to 500%, the organic solvent (C) is a mixed liquid of solvent (C1) and solvent (C2), in which solvent (C1) is one or more solvents selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons, solvent (C2) is one or more solvents selected from the group consisting of alcohol-based solvents, ketone-based solvents, ester-based solvents, and glycol ether-based solvents, and the mass ratio of solvent (C1):solvent (C2) is 50:50 to 97:3, with the total of these mass ratios being 100; Adhesive composition.

2. The adhesive composition according to claim 1, which is used to bond a polyolefin resin substrate to a metal substrate.

3. A laminate comprising a polyolefin resin substrate and a metal substrate bonded with the adhesive composition according to claim 1 or 2.

4. A packaging material for lithium ion batteries, comprising the laminate according to claim 3 as a constituent member.

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