Adhesive composition, two-part adhesive composition, and laminate

Abstract

This adhesive composition comprises an acid-modified polyolefin and an epoxy resin, wherein the acid-modified polyolefin satisfies the following requirements (I)-(iii), the epoxy resin has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a butadiene-derived constitutional unit, and the content of the epoxy resin is 2-40 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin.　Requirement (I): the acid-modified polyolefin is an acid-modified product of a homopolymer of butene or an acid-modified product of a butene copolymer.　Requirement (ii): the acid-modified polyolefin has an acid value of 0.1 mgKOH / g to 15 mgKOH / g.　Requirement (iii): the acid-modified polyolefin has a weight average molecular weight of at least 80,000.

Description

Adhesive composition, two-component adhesive composition, and laminate

[0001] The present disclosure relates to an adhesive composition, a two-component adhesive composition, and a laminate.

[0002] Adhesive compositions for bonding metal materials such as aluminum and copper are used in industrial products such as electronic devices and batteries. Long-term chemical resistance is also required for battery applications. Adhesive compositions using acid-modified polyolefins are known as materials that satisfy both adhesion to metals and chemical resistance.

[0003] For example, Patent Document 1 discloses that a composition using an acid-modified polyolefin with a high acid value exhibits high chemical resistance.

[0004] Furthermore, Patent Documents 2 and 3 disclose that high chemical resistance can be achieved by using an acid-modified polyolefin having a low acid value and blending 2 parts or less of an epoxy resin with 100 parts of the acid-modified polyolefin.

[0005] JP 2020-169250 A International Publication No. 2017 / 126520 International Publication No. 2021 / 131722

[0006] In recent years, such adhesives have been required to have long-term chemical resistance. Although the adhesive compositions described in Patent Documents 1 to 3 can exhibit short-term chemical resistance, it is difficult to maintain performance over a long period of time.

[0007] The problem to be solved by the present disclosure is to provide an adhesive composition that exhibits excellent chemical resistance for a long period of time after curing. Another problem to be solved by the present disclosure is to provide a two-component adhesive composition that exhibits excellent chemical resistance for a long period of time after curing. Yet another problem to be solved by the present disclosure is to provide a laminate using the adhesive composition or the two-component adhesive composition.

[0008] Specific means for solving the above problems include the following aspects. <1> An adhesive composition comprising an acid-modified polyolefin and an epoxy resin, wherein the acid-modified polyolefin satisfies the following requirements (i) to (iii), the epoxy resin has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a butadiene-derived structural unit, and the content of the epoxy resin is 2 to 40 parts by mass per 100 parts by mass of the acid-modified polyolefin. Requirement (i): The epoxy resin is an acid-modified product of a butene homopolymer or an acid-modified product of a butene copolymer. Requirement (ii): The acid value is 0.1 mg KOH / g to 15 mg KOH / g. Requirement (iii): The weight-average molecular weight is 80,000 or more. <2> The adhesive composition according to <1>, wherein the acid-modified polyolefin is a maleic anhydride-modified polyolefin. <3> The adhesive composition according to <1> or <2>, wherein the acid-modified polyolefin is an acid-modified copolymer of propylene and 1-butene. <4> The adhesive composition according to any one of <1> to <3>, wherein the acid-modified polyolefin has an acid value of 1 mgKOH / g to 10 mgKOH / g. <5> The adhesive composition according to any one of <1> to <4>, wherein the acid-modified polyolefin has a weight-average molecular weight of 90,000 to 200,000. <6> The adhesive composition according to any one of <1> to <5>, further comprising a curing accelerator, wherein the curing accelerator comprises an imidazole compound. <7> The adhesive composition according to any one of <1> to <6>, further comprising an aromatic solvent, an alicyclic solvent, and a ketone solvent. <8> The adhesive composition according to any one of <1> to <7>, wherein the adhesive composition is an adhesive composition for use between metal materials. <9> A two-component adhesive composition comprising an acid-modified polyolefin and an epoxy resin, wherein the acid-modified polyolefin satisfies the following requirements (i) to (iii), and the epoxy resin has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a structural unit derived from butadiene, and the adhesive composition comprises a first agent containing the epoxy resin in an amount of 2 to 40 parts by mass per 100 parts by mass of the acid-modified polyolefin, and a second agent containing a curing accelerator.Requirement (i): The acid-modified polyolefin is an acid-modified homopolymer or an acid-modified butene copolymer. Requirement (ii): The acid value is 0.1 mgKOH / g to 15 mgKOH / g. Requirement (iii): The weight-average molecular weight is 80,000 to 300,000. <10> The two-component adhesive composition according to <9>, wherein the acid-modified polyolefin is a maleic anhydride-modified polyolefin. <11> The two-component adhesive composition according to <9> or <10>, wherein the acid-modified polyolefin is an acid-modified copolymer of propylene and 1-butene. <12> The two-component adhesive composition according to any one of <9> to <11>, wherein the acid-modified polyolefin has an acid value of 1 mgKOH / g to 10 mgKOH / g. <13> The two-component adhesive composition according to any one of <9> to <12>, wherein the acid-modified polyolefin has a weight-average molecular weight of 90,000 to 200,000. <14> The two-component adhesive composition according to any one of <9> to <13>, wherein the curing accelerator comprises an imidazole compound. <15> The two-component adhesive composition according to any one of <9> to <14>, wherein the first part further comprises an aromatic solvent, an alicyclic solvent, and a ketone solvent. <16> The two-component adhesive composition according to any one of <9> to <15>, which is a two-component adhesive composition for use between metal materials. <17> A laminate formed by bonding a first metal material and a second metal material with an adhesive, wherein the adhesive is the adhesive composition according to any one of <1> to <8> or the two-component adhesive composition according to any one of <9> to <16>.

[0009] According to the present disclosure, an adhesive composition that exhibits excellent chemical resistance for an extended period after curing is provided. Also, according to the present disclosure, a two-component adhesive composition that exhibits excellent chemical resistance for an extended period after curing is provided. Furthermore, according to the present disclosure, a laminate using the adhesive composition or the two-component adhesive composition is provided.

[0010] An embodiment of the present disclosure will be described below. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the embodiments. In this disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In this disclosure, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the purpose of that process is achieved. When embodiments are described in this disclosure with reference to drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of components in each drawing are conceptual, and the relative size relationships between components are not limited thereto. In this disclosure, each component may contain multiple corresponding substances. In this disclosure, when referring to the amount of each component in a composition, if the composition contains multiple substances corresponding to each component, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In this disclosure, "(meth)acrylic" is an expression that includes both acrylic and methacrylic, and "(meth)acrylate" is an expression that includes both acrylate and methacrylate.

[0011] (Adhesive Composition) The adhesive composition according to the present disclosure comprises an acid-modified polyolefin and an epoxy resin, wherein the acid-modified polyolefin satisfies the following requirements (i) to (iii): the epoxy resin has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a butadiene-derived structural unit, and the content of the epoxy resin is 2 to 40 parts by mass per 100 parts by mass of the acid-modified polyolefin. Requirement (i): The epoxy resin is an acid-modified polybutene homopolymer or an acid-modified butene copolymer. Requirement (ii): The acid value is 0.1 mgKOH / g to 15 mgKOH / g. Requirement (iii): The weight-average molecular weight is 80,000 or more.

[0012] As described above, conventional adhesive compositions such as those described in Patent Documents 1 to 3 can exhibit short-term chemical resistance, but it is difficult to maintain performance over the long term. As a result of detailed studies by the present inventors, it has been found that an adhesive comprising an acid-modified polyolefin and an epoxy resin, wherein the acid-modified polyolefin satisfies the above requirements (i) to (iii), the epoxy resin has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a butadiene-derived structural unit, and the epoxy resin is contained in an amount of 2 to 40 parts by mass per 100 parts by mass of the acid-modified polyolefin, is presumed to result in a cured product of the adhesive composition exhibiting high crystallinity and a high crosslink density, and exhibiting excellent chemical resistance over a long period of time after curing.

[0013] The adhesive composition according to the present disclosure will be described in detail below.

[0014] <Acid-Modified Polyolefin> The adhesive composition according to the present disclosure contains an acid-modified polyolefin, and the acid-modified polyolefin satisfies the following requirements (i) to (iii). Requirement (i): The acid-modified polyolefin is an acid-modified product of a butene homopolymer or an acid-modified product of a butene copolymer. Requirement (ii): The acid value is 0.1 mg KOH / g to 15 mg KOH / g. Requirement (iii): The weight-average molecular weight is 80,000 or more. The acid-modified polyolefin is an acid-modified polyolefin obtained by modifying a polyolefin (hereinafter also referred to as "unmodified polyolefin") to impart acid groups. Specifically, the acid-modified polyolefin is obtained by modifying an unmodified polyolefin with an acid group-containing monomer.

[0015] Specific examples of unmodified polyolefins include butene homopolymers and butene copolymers. From the viewpoint of long-term chemical resistance after curing (hereinafter also simply referred to as "chemical resistance"), butene copolymers are preferred, 1-butene copolymers are more preferred, and propylene and 1-butene copolymers are particularly preferred. The butene copolymers may be random copolymers or block copolymers. Examples of butenes used in butene homopolymers or copolymers include 1-butene and isobutylene, with 1-butene being preferred. Examples of monomers other than butene used in butene copolymers include ethylene, propylene, and α-olefins other than 1-butene and isobutylene. Here, examples of α-olefins other than 1-butene include 1-hexene and 1-octene.

[0016] In the acid group-containing monomer for modifying unmodified polyolefin, examples of the acid group include a carboxylic acid group, a carboxylic acid anhydride group, a sulfonic acid group, and a phosphoric acid group. Among these, carboxylic acid groups and carboxylic acid anhydride groups are preferred because they are easy to modify, and carboxylic acid anhydride groups are particularly preferred. Hereinafter, carboxylic acid group-containing monomers used in the acid group-containing monomer will be described, but these may be the same or may be those that form a carboxylic acid anhydride group with other carboxylic acid group-containing monomers, including carboxylic acid anhydride group-containing monomers. In particular, unsaturated dicarboxylic acid compounds in which a carboxylic acid group is condensed to form a carboxylic acid anhydride group are preferred.

[0017] The carboxylic acid group (or carboxylic anhydride group)-containing monomer is a compound having an ethylenic double bond and a carboxylic acid group in the same molecule, and examples thereof include various unsaturated monocarboxylic acid compounds, unsaturated dicarboxylic acid compounds, and unsaturated tricarboxylic acid compounds. Specific examples of unsaturated monocarboxylic acid compounds include acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid. Examples of unsaturated dicarboxylic acid compounds include maleic acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, nadic acid, and endic acid. Examples of unsaturated tricarboxylic acid compounds include aconitic acid. As the acid group-containing monomer, unsaturated dicarboxylic acid compounds and unsaturated tricarboxylic acid compounds are preferred, with itaconic acid, maleic acid, and aconitic acid being particularly preferred, due to their ease of modification and excellent adhesive properties. The acid group-containing monomer may be used alone or in combination of two or more types.

[0018] Among these, maleic acid or maleic anhydride is preferably used because of its high modifying effect, and maleic anhydride is particularly preferably used. That is, the acid-modified polyolefin is preferably a maleic anhydride-modified polyolefin.

[0019] The acid-modified polyolefin may be modified (e.g., graft-modified) with an alkyl (meth)acrylate ester together with an acid group-containing monomer. The alkyl (meth)acrylate ester is preferably an ester of an alkyl alcohol having 8 to 18 carbon atoms with (meth)acrylic acid.

[0020] The graft modification may be carried out by a known method, for example, by grafting an acid compound together with a polyolefin in a molten or solution state in the presence of a radical polymerization initiator such as an organic peroxide or an aliphatic azo compound.

[0021] The temperature of the grafting reaction is preferably 80° C. to 160° C. when the reaction is carried out in a solution state, and 150° C. to 300° C. when the reaction is carried out in a molten state. In both the solution state and the molten state, the reaction rate increases at or above the lower limit of the reaction temperature range described above, while a decrease in the molecular weight of the resin can be suppressed at or below the upper limit of the reaction temperature range described above, and the mechanical strength of the resulting acid-modified polyolefin can be maintained.

[0022] The radical polymerization initiator to be used may be selected from commercially available organic peroxides, taking into consideration the reaction temperature and the like.

[0023] If a portion of the acid compound used for graft modification remains unreacted, it is preferable to remove the unreacted acid compound by a known method such as distillation under reduced pressure in order to prevent adverse effects on adhesive strength.

[0024] The acid value can be used as a measure of the amount of functional groups introduced into the acid-modified polyolefin. The acid value of the acid-modified polyolefin is 0.1 mgKOH / g to 15.0 mgKOH / g, and from the viewpoints of adhesiveness and chemical resistance, it is preferably 0.5 mgKOH / g to 12.5 mgKOH / g, and more preferably 1 mgKOH / g to 10 mgKOH / g. If the acid value of the acid-modified polyolefin is less than 0.1 mgKOH / g, the adhesive strength will be insufficient, and if it exceeds 15.0 mgKOH / g, the crystallinity of the resin will decrease due to the modification, resulting in a decrease in chemical resistance.

[0025] From the viewpoint of heat resistance, the melting point of the acid-modified polyolefin is preferably 50° C. to 120° C., more preferably 70° C. to 110° C., and even more preferably 80° C. to 95° C. When the melting point is within the above range, the acid-modified polyolefin has excellent chemical resistance and excellent solubility in solvents.

[0026] The weight average molecular weight Mw of the acid-modified polyolefin is 80,000 or more, preferably 90,000 to 300,000, more preferably 90,000 to 200,000, and particularly preferably 130,000 to 200,000. Within the above range, the acid-modified polyolefin has excellent chemical resistance and solubility in solvents. The weight average molecular weight Mw of the acid-modified polyolefin is the value obtained by converting the molecular weight measured by gel permeation chromatography into polystyrene equivalent.

[0027] From the viewpoint of improving adhesiveness, the propylene unit content in the acid-modified polyolefin is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0028] The acid-modified polyolefin may be used alone or in combination of two or more. From the viewpoint of chemical resistance, the content of the acid-modified polyolefin is preferably 60% by mass to 98% by mass, more preferably 70% by mass to 97% by mass, and particularly preferably 80% by mass to 97% by mass, based on all components of the adhesive composition other than the solvent (total solid content of the adhesive composition).

[0029] As the acid-modified polyolefin, commercially available products may be used, and examples of commercially available products include "MODIC" manufactured by Mitsubishi Chemical Corporation, "ADMER" and "UNISTOR" manufactured by Mitsui Chemicals, Inc., "TOYOTAC" manufactured by Toyobo Co., Ltd., and "UMEX" manufactured by Sanyo Chemical Industry Co., Ltd.

[0030] <Epoxy Resin> The adhesive composition according to the present disclosure contains an epoxy resin, and the epoxy resin has at least one structure selected from the group consisting of a bridged alicyclic hydrocarbon structure, an aromatic ring structure having a hydroxy group and an alkyl group, a polycyclic aromatic hydrocarbon structure, and a butadiene-derived structural unit. Examples of the bridged alicyclic hydrocarbon structure include a dicyclopentadiene structure, a norbornane structure, and an adamantane structure. Examples of the aromatic ring structure having a hydroxy group and an alkyl group include a cresol structure and a xylenol structure. Examples of the polycyclic aromatic hydrocarbon structure include a naphthalene structure, an anthracene structure, a phenanthrene structure, and a pyrene structure. From the viewpoint of chemical resistance, the epoxy resin used in the present disclosure preferably has at least one structure selected from the group consisting of a bridged alicyclic hydrocarbon structure, an aromatic ring structure having a hydroxy group and an alkyl group, and a polycyclic aromatic hydrocarbon structure, more preferably at least one structure selected from the group consisting of a bridged alicyclic hydrocarbon structure and an aromatic ring structure having a hydroxy group and an alkyl group, and particularly preferably a bridged alicyclic hydrocarbon structure.

[0031] Examples of epoxy resins having the above structure include dicyclopentadiene skeleton-containing epoxy resins, cresol novolac epoxy resins, naphthalene structure-containing epoxy resins, epoxidized polybutadiene, etc. From the viewpoint of chemical resistance, the epoxy resin used in the present disclosure preferably has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a butadiene-derived structural unit, more preferably has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, and a naphthalene structure, still more preferably has at least one structure selected from the group consisting of a dicyclopentadiene structure and a cresol structure, and particularly preferably has a dicyclopentadiene structure.

[0032] The epoxy resin is preferably a compound having two or more epoxy groups in one molecule. This is because a crosslinked structure is formed by reaction with the acid-modified polyolefin, thereby exhibiting high adhesiveness and chemical resistance. Furthermore, when an epoxy resin having two or more epoxy groups is used, the degree of crosslinking with the acid-modified polyolefin is sufficient, resulting in sufficient chemical resistance.

[0033] From the viewpoints of adhesiveness and chemical resistance, the epoxy equivalent of the epoxy resin is preferably 50 g / eq to 400 g / eq, more preferably 100 g / eq to 350 g / eq, and particularly preferably 200 g / eq to 300 g / eq. The epoxy equivalent of the epoxy resin in the present disclosure is defined as the mass of the epoxy resin containing one equivalent of epoxy groups, and means a measured value obtained in accordance with JIS K 7236:2001.

[0034] The epoxy resin may be used alone or in combination of two or more. The content of the epoxy resin is 2 to 40 parts by mass relative to 100 parts by mass of the acid-modified polyolefin, and from the viewpoints of adhesiveness and chemical resistance, it is preferably 2 to 30 parts by mass, more preferably 3 to 20 parts by mass, and particularly preferably 4 to 10 parts by mass. If the content of the epoxy resin is less than 2 parts by mass or more than 40 parts by mass, chemical resistance will decrease.

[0035] <Curing Accelerator> From the viewpoint of curability and curing rate, the adhesive composition according to the present disclosure preferably contains a curing accelerator. From the viewpoint of curability and curing rate, the curing accelerator preferably contains at least one compound selected from the group consisting of an imidazole compound, an amine compound, and a phosphorus compound, and more preferably contains an imidazole compound. The curing accelerator may be a catalyst added from the viewpoint of promoting the reaction of the curing agent.

[0036] Examples of the imidazole compound include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'- undecylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and the like.

[0037] Examples of the amine compound include tertiary amines such as benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylguanidine, triethanolamine, N,N'-dimethylpiperazine, triethylenediamine, and 1,8-diazabicyclo[5.4.0]undecene. Examples of the amine compound also include tertiary amine salts such as the formate, octylate, p-toluenesulfonate, o-phthalate, phenol salt, and phenol novolac resin salt of 1,8-diazabicyclo[5.4.0]undecene; and the formate, octylate, p-toluenesulfonate, o-phthalate, phenol salt, and phenol novolac resin salt of 1,5-diazabicyclo[4.3.0]nonene.

[0038] Examples of the phosphorus compound include triphenylphosphine, tributylphosphine, methyldiphenylphosphine, tris(4-methylphenyl)phosphine, tris(4-butylphenyl)phosphine, diphenylphosphine, and phenylphosphine.

[0039] The content of the curing accelerator can be appropriately determined depending on the type and amount of the acid-modified polyolefin, the type and amount of the curing accelerator, etc. Only one type of curing accelerator may be used, or two or more types may be used. From the viewpoint of curability and curing rate, the content of the curing accelerator is preferably 0.01 to 2 parts by mass, more preferably 0.02 to 1.5 parts by mass, and particularly preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the acid-modified polyolefin.

[0040] <Other Polymers> The adhesive composition according to the present disclosure may contain other polymers in addition to the acid-modified polyolefin and high molecular weight epoxy resin described above for the purposes of improving adhesion, hydrolysis resistance, heat resistance, etc. When the adhesive composition contains other polymers, the other polymers may be one type or two or more types.

[0041] Other polymers include, for example, phenolic resins, urea resins, melamine resins, benzoguanamine resins, alkyd resins, unsaturated polyester resins, vinyl ester resins, diallyl terephthalate resins, silicone resins, urethane resins, furan resins, ketone resins, xylene resins, thermosetting polyimide resins, benzoxazine resins, active ester resins, aniline resins, cyanate ester resins, styrene-maleic anhydride (SMA) resins, polyethylene resins, polypropylene resins, polystyrene resins, rubber-modified polystyrene resins, acrylonitrile-butadiene-styrene (ABS) resins, acrylonitrile-styrene (AS) resins, polymethyl methacrylate resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyethylene terephthalate resins, ethylene vinyl alcohol resins, cellulose acetate resins, ionomer resins, polyacrylonitrile resins, poly Examples of the resin include amide resins, polyacetal resins, polybutylene terephthalate resins, polylactic acid resins, polyphenylene ether resins, modified polyphenylene ether resins, polycarbonate resins, polysulfone resins, polyphenylene sulfide resins, polyetherimide resins, polyethersulfone resins, polyarylate resins, thermoplastic polyimide resins, polyamideimide resins, polyetheretherketone resins, polyketone resins, liquid crystal polyester resins, fluororesins, syndiotactic polystyrene resins, cyclic polyolefin resins, α-olefin copolymers, propylene-based elastomers, polyisoprene, hydrogenated polyisoprene, polybutadiene, cycloolefin polymers, cycloolefin copolymers, polyamines, polyamides, melamine resins, urea resins, styrene-based thermoplastic resins, hydroxyl group-modified polyolefin resins, and glycidyl methacrylate-modified polyolefin resins.

[0042] The other polymer may be used alone or in combination of two or more kinds. The content of the other polymer is preferably less than the content of the acid-modified polyolefin, and more preferably less than the content of the epoxy resin.

[0043] <Additives> The adhesive composition according to the present disclosure may further contain additives other than those described above. Known additives can be used as the additive, and preferred examples include at least one additive selected from the group consisting of antioxidants, UV absorbers, fillers, reinforcing fibers, release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.

[0044] <Solvent> From the viewpoints of stability over time, coatability, and handleability, the adhesive composition according to the present disclosure preferably further contains a solvent. Examples of solvents that can be used in the adhesive composition according to the present disclosure include well-known solvents. Specific examples of solvents include aromatic solvents such as toluene and xylene; aliphatic solvents such as n-hexane; alicyclic solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane; ketone solvents such as acetone and methyl ethyl ketone; alcohol solvents such as methanol and ethanol; ester solvents such as ethyl acetate and butyl acetate; and propylene glycol ether solvents such as propylene glycol methyl ether, propylene glycol ethyl ether, and propylene glycol t-butyl ether. These solvents may be used alone or in combination of two or more.

[0045] Among these, from the viewpoint of inhibiting solidification and inhibiting thickening over time, the solvent preferably contains at least one solvent A selected from an aromatic solvent, an aliphatic solvent, a ketone solvent, and an alcohol solvent, and more preferably contains an aromatic solvent, an alicyclic solvent, and a ketone solvent.

[0046] - Aromatic Solvent - Aromatic solvents are solvents having an aromatic ring in one molecule. Examples of aromatic solvents include toluene, o-xylene, m-xylene, p-xylene, anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetole, butyl phenyl ether, ethyl benzene, diethyl benzene, pentyl benzene, isopropyl benzene, cymene, and mesitylene. Among these, aromatic solvents having 6 to 8 carbon atoms and a low number of substituents (particularly toluene) are preferred from the viewpoint of suppressing solidification and suppressing thickening over time.

[0047] Ketone solvents are solvents that have a ketone group in one molecule, and examples of ketone solvents include methyl ethyl ketone, acetone, diethyl ketone, methyl isobutyl ketone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone.

[0048] An alcohol-based solvent is a solvent having an alcoholic hydroxyl group in one molecule. Examples of alcohol-based solvents include methanol, ethanol, isopropyl alcohol, normal propyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol.

[0049] Among these, from the viewpoint of inhibiting solidification and inhibiting thickening over time, a lower alkyl ketone having 3 to 5 carbon atoms (particularly methyl ethyl ketone) is preferred as the ketone solvent, and a lower alcohol having 1 to 4 carbon atoms (particularly isopropyl alcohol) is preferred as the alcohol solvent.

[0050] - Aliphatic Solvent - Aliphatic solvents are solvents having an aliphatic group in one molecule. Examples of aliphatic solvents include n-heptane, n-hexane, octane, nonane, decane, undecane, dodecane, and isododecane; alicyclic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, and dimethylcyclohexane; and paraffinic solvents. Among these, alicyclic solvents (particularly methylcyclohexane) are preferred as aliphatic solvents in terms of preventing solidification and viscosity increase over time.

[0051] -Solvent Component Ratio- From the viewpoint of inhibiting solidification and inhibiting thickening over time, when the total amount of solvents is taken as 100 parts by mass, the preferred amount of each solvent is as follows. The amount of aromatic solvent is preferably 10 parts by mass to 45 parts by mass, more preferably 10 parts by mass to 30 parts by mass, and particularly preferably 10 parts by mass to 20 parts by mass. The amount of at least one solvent selected from the group consisting of ketone solvents and alcohol solvents is preferably 5 parts by mass to 20 parts by mass, more preferably 8 parts by mass to 20 parts by mass, and particularly preferably 10 parts by mass to 20 parts by mass. The amount of aliphatic solvent is preferably 45 parts by mass to 70 parts by mass, more preferably 55 parts by mass to 70 parts by mass, and particularly preferably 60 parts by mass to 70 parts by mass.

[0052] From the viewpoint of suppressing solidification and thickening over time, the ratio of the aromatic solvent to the aliphatic solvent is preferably 15% by mass to 25% by mass, more preferably 15% by mass to 23% by mass, and even more preferably 15% by mass to 20% by mass. From the viewpoint of suppressing solidification and thickening over time, the ratio of at least one solvent selected from the group consisting of ketone solvents and alcohol solvents is preferably 5% by mass to 35% by mass, more preferably 10% by mass to 35% by mass, and even more preferably 15% by mass to 35% by mass.

[0053] The solvent may contain solvents other than aromatic solvents, ketone solvents, alcohol solvents, and aliphatic solvents. However, the proportion of aromatic solvents, ketone solvents, alcohol solvents, and aliphatic solvents in the solvent is preferably 90% by mass or more, more preferably 95% by mass or more. The proportion of aromatic solvents, ketone solvents, alcohol solvents, and aliphatic solvents in the solvent is preferably 100% by mass.

[0054] The content of the solvent is preferably 75% by mass to 95% by mass, and more preferably 80% by mass to 90% by mass, based on the total mass of the adhesive composition.

[0055] <Applications> The adhesive composition according to the present disclosure has excellent long-term chemical resistance after curing, making it suitable for use in electronic devices and batteries. Because of this chemical resistance, the adhesive composition also has excellent electrolyte resistance, making it particularly suitable for use in batteries. Furthermore, the adhesive composition according to the present disclosure has excellent adhesion between metal materials, making it suitable for use in bonding these materials. The metal materials to be bonded may be of the same type or different types. Furthermore, because the adhesive composition according to the present disclosure has the above-described properties, it can be used as an adhesive for automobiles and other vehicles (bullet trains and trains), ships, aircraft, architecture, civil engineering, electronics, the aerospace industry, and other industrial products.

[0056] (Two-component adhesive composition) The two-component adhesive composition according to the present disclosure comprises an acid-modified polyolefin and an epoxy resin, wherein the acid-modified polyolefin satisfies the following requirements (i) to (iii): the epoxy resin has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a butadiene-derived structural unit, and the adhesive composition comprises a first agent containing 2 to 40 parts by mass of the epoxy resin per 100 parts by mass of the acid-modified polyolefin, and a second agent containing a curing accelerator. Requirement (i): The adhesive is an acid-modified butene homopolymer or an acid-modified butene copolymer. Requirement (ii): The acid value is 0.1 mgKOH / g to 15 mgKOH / g. Requirement (iii): The weight-average molecular weight is 80,000 or more.

[0057] Preferred aspects of the first part in the two-component adhesive composition according to the present disclosure are the same as the preferred aspects of the adhesive composition according to the present disclosure described above, except as described below. The first part preferably does not contain a curing accelerator.

[0058] Preferred aspects of the curing accelerator in the second part of the two-component adhesive composition according to the present disclosure are the same as the preferred aspects of the curing accelerator in the adhesive composition according to the present disclosure described above, except as described below. The content of the curing accelerator in the second part is not particularly limited, but from the viewpoints of curability and curing rate, it is preferably 0.1% by mass to 20% by mass, more preferably 1% by mass to 10% by mass, and particularly preferably 2.5% by mass to 5% by mass, relative to the total mass of the second part.

[0059] From the viewpoints of the solubility of the curing accelerator and stability over time, the solvent contained in the second agent preferably contains at least one solvent A selected from ketone-based solvents and alcohol-based solvents, and more preferably contains both a ketone-based solvent and an alcohol-based solvent. Furthermore, from the viewpoints of the solubility of the curing accelerator and stability over time, it is particularly preferable that the solvent contained in the second agent contains more alcohol-based solvents than ketone-based solvents. From the viewpoints of the solubility of the curing accelerator and stability over time, the amount of ketone-based solvent is preferably 10% to 50% by mass, more preferably 20% to 45% by mass, and particularly preferably 30 parts by mass to 40 parts by mass, relative to the total mass of the second agent. From the viewpoints of the solubility of the curing accelerator and stability over time, the amount of alcohol-based solvent is preferably 30% to 90% by mass, more preferably 40% to 75% by mass, and particularly preferably 50% to 65% by mass.

[0060] The solvent contained in the second agent may contain a solvent other than a ketone solvent, an alcohol solvent, and an aliphatic solvent. However, the proportion of the ketone solvent and the alcohol solvent in the solvent is preferably 90% by mass or more, more preferably 95% by mass or more. The proportion of the ketone solvent and the alcohol solvent in the solvent is preferably 100% by mass.

[0061] The content of the solvent in the second agent is preferably 80% by mass to 99.9% by mass, and more preferably 90% by mass to 99% by mass, based on the total mass of the second agent.

[0062] (Laminate) The laminate according to the present disclosure is a laminate in which a first metal material and a second metal material are bonded with an adhesive, and the adhesive is the adhesive composition according to the present disclosure or the two-component adhesive composition according to the present disclosure.

[0063] <Metallic Material> Examples of metals constituting the first metallic material and the second metallic material include one or more selected from copper, stainless steel, brass, silver, aluminum, nickel, etc. The first metallic material and the second metallic material may be metallic materials of the same type or different types. In order to improve adhesion, the first metallic material and the second metallic material may have a metal substrate surface that is roughened or may be treated to remove residual oil from the metal substrate surface.

[0064] The shapes of the first metal material and the second metal material are not particularly limited, and may be any desired shape. For example, when the first metal material and the second metal material are plate-shaped metal substrates, the thickness of the metal substrate is preferably 1 μm or more and 200 μm or less, more preferably 3 μm or more and 100 μm or less, and even more preferably 6 μm or more and 50 μm or less. By making the thickness 1 μm or more, the strength of the connector can be easily improved. Furthermore, by making the thickness 1 μm or more, a predetermined strength can be imparted to the metal substrate, and damage to the substrate when stress is applied to the substrate can be easily suppressed.

[0065] The adhesive composition is preferably formed on the first metal material and / or the second metal material by a coating method. For example, the adhesive composition can be applied to the first metal material using a coating device, the solvent can be evaporated to form a metal material with a coating film, the resulting metal material with the coating film and the second metal material can be bonded together, and the coating film can be cured to form an adhesive layer. When a two-component adhesive composition is used, the adhesive layer can be formed by, for example, applying a first part to the first metal material using a coating device, evaporating the solvent to form a first metal material with a coating film, applying a second part to the second metal material using a coating device, evaporating the solvent to form a second metal material with a coating film, bonding the resulting first metal material with the coating film and the second metal material with the coating film, and then curing the coating film. Alternatively, for example, the first agent and the second agent may be mixed immediately before application, the mixture of the first agent and the second agent may be applied to the first metal material using an application means, the solvent may be evaporated to form a metal material with a coating film, the resulting metal material with the coating film may be bonded to the second metal material, and the coating film may then be hardened to form an adhesive layer.

[0066] Examples of means for applying the adhesive composition or two-component adhesive composition include a bar coater, a spray gun, a dispenser, a roll coater, a curtain coater, and a dip coater.

[0067] The temperature and time for volatilizing the solvent can be appropriately set in consideration of the type of solvent, etc., and can be, for example, 50° C. to 200° C. and 0.1 to 5 minutes.

[0068] The laminate according to the present disclosure can be produced, for example, as follows. First, a metal material with a coating film obtained by applying the adhesive composition according to the present disclosure and a second metal material are each prepared in advance. Next, the surface of the metal material on which the coating film is disposed is placed opposite the second metal material, and a multi-layer laminate is obtained by thermal lamination. Next, the laminate is cured to harden the coating film.

[0069] Thermal lamination can be performed using a known laminator. There are no limitations on the lamination conditions, and general conditions can be applied. The lamination temperature is preferably 50°C to 200°C, and more preferably 80°C to 150°C. The conveying speed during lamination is preferably 0.01 m / min to 200 m / min, and more preferably 0.1 m / min to 100 m / min. The lamination pressure is preferably 0.01 MPa to 10 MPa, and more preferably 0.1 MPa to 5 MPa.

[0070] By curing the laminate after thermal lamination, the curing of the coating film progresses, and a laminate in which the first metal material, the adhesive layer, and the second metal material are more firmly bonded can be obtained. The curing conditions may be, for example, leaving the laminate at rest at a temperature of 40°C to 150°C for 0.5 to 7 days.

[0071] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to the following examples.

[0072] <Method for measuring the acid value of acid-modified polyolefin> Approximately 10 g of acid-modified polyolefin was accurately weighed and placed in a 200 mL tall beaker. 150 mL of a mixed solvent consisting of xylene and dimethylformamide mixed at a 1:1 (volume ratio) was added as the titration solvent. Titration was performed using a 1 w / v% phenolphthalein ethanol solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as an indicator, and the acidity was determined from the titration amount. Specifically, the acid value was calculated using the following formula. In the present invention, the acid value is the average value of three repeated titrations. Acid value (mgKOH / g)=(EP1-BL1)×FA1×C1 / SIZE In the above formula, "EP1" represents the titration amount (mL), "BL1" represents the blank value (mL), "FA1" represents the factor of the titrant (1.00), "C1" represents the concentration equivalent value (5.611 mg / m), and "SIZE" represents the amount of acid-modified polyolefin collected (g).

[0073] <Method for measuring melting point of acid-modified polyolefin> Using a differential scanning calorimeter (Q-2000, manufactured by TA Instruments Japan), the melting point of the acid-modified polyolefin was measured from the top temperature of the melting peak when the polyolefin was heated and melted at a rate of 20°C / min, cooled to form a resin, and then heated and melted again.

[0074] <Adhesive composition materials> 1. Acid-modified polyolefins Acid-modified polyolefin-1 (PO-1) Propylene-butene-1 copolymer, melting point 80°C, molecular weight Mw 97,000, acid value 13 mg KOH / g Acid-modified polyolefin-2 (PO-2) Propylene-butene-1 copolymer, melting point 84°C, molecular weight Mw 106,000, acid value 9 mg KOH / g Acid-modified polyolefin-3 (PO-3) Propylene-butene-1 copolymer, melting point 80°C, molecular weight Mw 145,000, acid value 10 mg KOH / g Acid-modified polyolefin-4 (PO-4) Propylene-butene-1 copolymer, melting point 79°C, molecular weight Mw 183,000, acid value 6 mg KOH / g Acid-modified polyolefin-5 (PO-5) Propylene-butene-1 copolymer, melting point 76°C, molecular weight Mw 118,000, acid value 9 mg KOH / g. Acid-modified polyolefin-6 (PO-6) Propylene-butene-1 copolymer, melting point 84°C, molecular weight Mw 57,000, acid value 23 mg KOH / g. Acid-modified polyolefin-7 (PO-7) Propylene-butene-1 copolymer, melting point 93°C, molecular weight Mw 68,000, acid value 17 mg KOH / g.

[0075] 2. Epoxy Resins Epoxy Resin-1 (E-1) EPICLONHP-7200 (DIC Corporation), dicyclopentadiene skeleton-containing epoxy resin, epoxy equivalent 260 g / eq. Epoxy Resin-2 (E-2) JP-200 (Nippon Soda Co., Ltd.), epoxidized polybutadiene, epoxy equivalent 220 g / eq. Epoxy Resin-3 (E-3) NC-7000H (Nippon Kayaku Co., Ltd.), naphthalene-containing cresol novolac epoxy resin, epoxy equivalent 227 g / eq. Epoxy Resin-4 (E-4) jER828 (Mitsubishi Chemical Corporation), bisphenol A epoxy resin, epoxy equivalent 190 g / eq.

[0076] 3. Curing accelerator: Curesol C11Z (manufactured by Shikoku Chemicals Corporation, imidazole compound)

[0077] <Preparation of Solution A> Preparation of Solution A1 (A-1) 13.9 g of maleic acid-modified polyolefin (PO-1) was dissolved in a mixed solvent of 10.6 g of toluene, 14.9 g of methyl ethyl ketone, and 59.5 g of methylcyclohexane at 60°C, and then 1.1 g of epoxy resin-1 (E-1) was dissolved therein to obtain Solution A1 (A-1).

[0078] Preparation of A-2 to A-19 (A-2 to A-19) Adhesives A-2 to A-19 were each prepared in the same manner as A-1, except that the components and blending amounts used were changed as shown in Table 1.

[0079]

[0080] <Preparation of Solution B> Preparation of Solution B 1 (B-1) Solution B 1 (B-1) was obtained by dissolving 4.0 g of Curesol SIZ (manufactured by Shikoku Chemicals Corporation) in a mixed solvent of 38.4 g of methyl ethyl ketone and 57.6 g of isopropyl alcohol.

[0081] Preparation of B Liquid 2 and B Liquid 3 (B-2 and B-3) Adhesives B-2 and B-3 were prepared in the same manner as B-1, except that the components and blending amounts used were changed as shown in Table 2.

[0082]

[0083] <Preparation of Adhesive Composition> Example 1 The adhesive composition of Example 1 was prepared by thoroughly mixing 100 parts of Liquid A 1 (A-1) and 1 part of Liquid B 1 (B-1).

[0084] (Examples 2 to 13 and Comparative Examples 1 to 6) The adhesive compositions of Examples 2 to 13 and Comparative Examples 1 to 6 were prepared in the same manner as in Example 1, except that the types and mixing amounts of the A and B solutions used were changed as shown in Table 3 or Table 4.

[0085] <Laminate> The obtained adhesive composition was applied to a 50 μm-thick aluminum foil (Al foil, surface untreated) using a bar coater to a coating thickness of 5 μm (dry film thickness), and a coated foil was obtained by volatilizing the solvent for 1 minute at 100° C. Thereafter, the coating surface of the obtained coated foil was bonded to a 12 μm-thick copper foil (Cu foil, electrolytic copper foil, surface untreated) at 100° C., and the coating was cured by aging at 80° C. for 2 days, thereby obtaining a laminate in which the Al foil, adhesive layer, and Cu foil were laminated in this order.

[0086] <Measurement of initial peel strength> Using an Autograph AG-X manufactured by Shimadzu Corporation, the interfacial adhesive strength between the aluminum foil and the copper foil of the laminate was evaluated under the conditions of a peel speed of 100 mm / min, a peel width of 15 mm, an atmospheric temperature of 23°C, and a T-type peeling form. The unit is N / mm.

[0087] <Evaluation of Solvent Resistance> A commercially available electrolyte solution (manufactured by Kishida Chemical Co., Ltd., ethylene carbonate:diethyl carbonate:dimethyl carbonate=1:1:1 (volume ratio), LiPF ６ The laminate was immersed in the electrolyte at 60°C for 150 hours, then removed and washed with acetone. The peel strength was measured in the same manner as in the measurement of the initial peel strength described above, and this was taken as the peel strength after 150 hours of immersion. Solvent resistance was evaluated as follows based on the peel strength after 150 hours of immersion.

[0088] -Evaluation criteria- A: Peel strength after immersion for 150 hours is 0.7 N / mm or more. B: Peel strength after immersion for 150 hours is 0.6 N / mm or more and less than 0.7 N / mm. C: Peel strength after immersion for 150 hours is 0.5 N / mm or more and less than 0.6 N / mm. D: Peel strength after immersion for 150 hours is less than 0.5 N / mm.

[0089]

[0090]

[0091] As shown in Tables 3 and 4, the adhesive compositions of Examples 1 to 13 were superior in chemical resistance over a long period of time after curing compared to the adhesive compositions of Comparative Examples 1 to 6.

[0092] The disclosure of Japanese Patent Application No. 2023-212416, filed on December 15, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. An adhesive composition comprising an acid-modified polyolefin and an epoxy resin, wherein the acid-modified polyolefin satisfies the following requirements (i) to (iii), the epoxy resin has at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a structural unit derived from butadiene, and the content of the epoxy resin is 2 to 40 parts by mass per 100 parts by mass of the acid-modified polyolefin. Requirement (i): The epoxy resin is an acid-modified product of a butene homopolymer or an acid-modified product of a butene copolymer. Requirement (ii): The acid value is 0.1 mgKOH / g to 15 mgKOH / g. Requirement (iii): The weight average molecular weight is 80,000 or more.

2. The adhesive composition according to claim 1, wherein the acid-modified polyolefin is a maleic anhydride-modified polyolefin.

3. The adhesive composition according to claim 1, wherein the acid-modified polyolefin is an acid-modified copolymer of propylene and 1-butene.

4. The adhesive composition according to claim 1, wherein the acid-modified polyolefin has an acid value of 1 mgKOH / g to 10 mgKOH / g.

5. The adhesive composition according to claim 1, wherein the weight average molecular weight of the acid-modified polyolefin is 90,000 to 200,000.

6. The adhesive composition according to claim 1, further comprising a curing accelerator, said curing accelerator comprising an imidazole compound.

7. The adhesive composition according to claim 1, further comprising an aromatic solvent, an alicyclic solvent and a ketone solvent.

8. The adhesive composition according to claim 1, which is an adhesive composition for bonding metal materials together.

9. A two-part adhesive composition comprising an acid-modified polyolefin and an epoxy resin, the acid-modified polyolefin satisfying the following requirements (i) to (iii), the epoxy resin having at least one structure selected from the group consisting of a dicyclopentadiene structure, a cresol structure, a naphthalene structure, and a butadiene-derived structural unit, and a first agent containing 2 to 40 parts by mass of the epoxy resin relative to 100 parts by mass of the acid-modified polyolefin, and a second agent containing a curing accelerator. Requirement (i): The acid-modified product is an acid-modified homopolymer of butene, or an acid-modified product of a butene copolymer. Requirement (ii): The acid value is 0.1 mgKOH / g to 15 mgKOH / g. Requirement (iii): The weight average molecular weight is 80,000 or more.

10. The two-component adhesive composition according to claim 9, wherein the acid-modified polyolefin is a maleic anhydride-modified polyolefin.

11. The two-component adhesive composition according to claim 9, wherein the acid-modified polyolefin is an acid-modified copolymer of propylene and 1-butene.

12. The two-component adhesive composition according to claim 9, wherein the acid-modified polyolefin has an acid value of 1 mgKOH / g to 10 mgKOH / g.

13. The two-component adhesive composition according to claim 9, wherein the weight average molecular weight of the acid-modified polyolefin is 90,000 to 200,000.

14. The two-component adhesive composition according to claim 9, wherein the curing accelerator comprises an imidazole compound.

15. The two-component adhesive composition according to claim 9, wherein the first part further comprises an aromatic solvent, an alicyclic solvent, and a ketone solvent.

16. The two-component adhesive composition according to claim 9, which is a two-component adhesive composition for bonding metal materials together.

17. A laminate comprising a first metal material and a second metal material bonded together with an adhesive, the adhesive being the adhesive composition according to any one of claims 1 to 8 or the two-component adhesive composition according to any one of claims 9 to 16.

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