Adhesives and adhesive films

Abstract

To provide an adhesive with excellent adhesion and vibration resistance in high-temperature environments. [Solution] The adhesive is an adhesive comprising a cured product of an adhesive composition containing a polymer component and a crosslinking agent, wherein the polymer component contains a (meth)acrylic polymer (P1) having a structural unit having a reactive group (R1) for forming a crosslinked structure with the crosslinking agent and having a weight-average molecular weight of 300,000 to 3,000,000, the crosslinking agent is an epoxy crosslinking agent, the gel fraction of the adhesive is 3% to 95% by mass, and in the differential molecular weight distribution curve of the sol component of the adhesive, the ratio of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight of 10,000 to 30,000,000 is more than 40%.

Description

[Technical Field]

[0001] This invention relates to an adhesive and an adhesive film using this adhesive. [Background technology]

[0002] In recent years, acrylic and epoxy adhesives have been used in fields such as automotive, marine, aerospace, civil engineering, and construction as structural adhesives to replace or reinforce conventional joining technologies such as welding, screws, and rivets. Acrylic adhesives are superior to epoxy adhesives in that they cure quickly at room temperature, but their working life is limited. Therefore, dedicated application equipment and strict condition control are required.

[0003] On the other hand, adhesives are widely used for fixing various parts because they offer excellent workability and quickly develop adhesive strength after application. Among them, adhesive films having an acrylic adhesive layer are widely used for fixing components in automobiles, electronic equipment, and buildings because they have excellent properties such as weather resistance, durability, heat resistance, and transparency. However, since adhesives have inferior adhesive strength compared to adhesives, methods such as incorporating low molecular weight sol components (such as tackifiers) into the adhesive layer or applying plasma treatment or corona treatment to the adhesive surface of the acrylic adhesive layer have been investigated (see Patent Document 1 (Claim 1, 6)). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-152184 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Components used in automobiles, such as electronic equipment, interior materials, and exterior materials, are exposed to high temperatures and vibrations during operation. Therefore, adhesives used in these components require resistance to peeling (adhesion) and vibration in high-temperature environments. However, conventional adhesives do not have sufficient adhesion and vibration resistance in high-temperature environments. This invention has been made in view of the above circumstances, and aims to provide an adhesive material with excellent adhesive strength and vibration resistance in high-temperature environments. [Means for solving the problem]

[0006] The adhesive of the present invention, which has been able to solve the above problems, is an adhesive comprising a cured product of an adhesive composition containing a polymer component and a crosslinking agent, wherein the polymer component contains a (meth)acrylic polymer (P1) having a structural unit having a reactive group (R1) for forming a crosslinked structure with the crosslinking agent and having a weight-average molecular weight of 300,000 to 3,000,000, the crosslinking agent is an epoxy crosslinking agent, the gel fraction of the adhesive is 3% to 95% by mass, and in the differential molecular weight distribution curve of the sol component of the adhesive, the ratio of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight of 10,000 to 30,000,000 is more than 40%.

[0007] The adhesive of the present invention uses a (meth)acrylic polymer (P1) having a predetermined weight-average molecular weight as the polymer component, and by controlling the gel fraction within a predetermined range, deformation due to externally applied force is suppressed, and vibration resistance is improved. Furthermore, in the adhesive of the present invention, by controlling the molecular weight of the sol component, the fluidity of the sol component is suppressed even in high-temperature environments, thereby suppressing the decrease in adhesive strength and vibration resistance in high-temperature environments. Therefore, the adhesive material of the present invention exhibits excellent adhesive strength and vibration resistance in high-temperature environments. [Effects of the Invention]

[0008] According to the present invention, an adhesive material with excellent adhesive strength and vibration resistance in high-temperature environments can be obtained. [Modes for carrying out the invention]

[0009] The following describes an example of a preferred embodiment of the present invention. However, the following embodiments are merely illustrative. The present invention is not limited in any way to the embodiments described below.

[0010] <Definition> In this specification, "(meth)acrylic" means "at least one of acrylic and methacrylic." "(meth)acrylate" means "at least one of acrylate and methacrylate." "(meth)acrylate" means "an ester compound in which a hydrogen atom of the carboxyl group of (meth)acrylic acid is replaced by an organic group." "(meth)acryloyl" means "at least one of acryloyl and methacryloyl." "(meth)acrylic monomer" means "a monomer having a (meth)acryloyl group in its molecule," and also includes "(meth)acrylate." "Vinyl monomer" means "a monomer having a radically polymerizable carbon-carbon double bond in its molecule," and also includes "(meth)acrylate" and "(meth)acrylic monomer."

[0011] In this specification, "structural unit derived from (meth)acrylate" means "a structural unit in which the radically polymerizable carbon-carbon double bond of (meth)acrylate polymerizes to form a carbon-carbon single bond." "Structural unit derived from (meth)acrylic monomer" means "a structural unit in which the radically polymerizable carbon-carbon double bond of (meth)acrylic monomer polymerizes to form a carbon-carbon single bond." "Structural unit derived from vinyl monomer" means "a structural unit in which the radically polymerizable carbon-carbon double bond of vinyl monomer polymerizes to form a carbon-carbon single bond."

[0012] As defined in JIS, a "sheet" refers to a thin, generally flat product whose thickness is small compared to its length and width. Generally, a "film" refers to a thin, flat product whose thickness is extremely small compared to its length and width, and whose maximum thickness is arbitrarily limited, and which is usually supplied in the form of a roll (Japanese Industrial Standard JIS K6900). For example, in terms of thickness, in a narrow sense, those with a thickness of 100 μm or more may be referred to as sheets, and those with a thickness of less than 100 μm may be referred to as films. However, the boundary between sheets and films is not clear, and since there is no need to distinguish between the two in the language of this specification, in this specification, when referring to a "sheet", it includes "films", and when referring to a "film", it includes "sheets".

[0013] In this specification, when described as "X to Y" (X and Y are arbitrary numbers), it means "X or more and Y or less". Also, when described as "X or more" (X is an arbitrary number), it also includes the meaning of "X or more than X", and when described as "Y or less" (Y is an arbitrary number), it also includes the meaning of "Y or less than Y". Furthermore, "X and / or Y" (X and Y are arbitrary components) means "at least one of X and Y", and has three meanings: "only X", "only Y", and "X and Y".

[0014] <Adhesive material> The adhesive material of the present invention is a cured product of an adhesive composition containing a polymer component and a crosslinking agent. The cured product has a crosslinked structure formed from the molecular chains of the polymer component and the crosslinking agent, and may have a crosslinked structure formed only from the crosslinking agent as long as it does not inhibit the effects of the present invention.

[0015] The gel fraction of the adhesive material is preferably 3% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 80% by mass or less. When the gel fraction, that is, the degree of crosslinking, is within the above range, a three-dimensional network structure is favorably formed by crosslinking, and an adhesive material excellent in adhesive force and vibration resistance in a high-temperature environment can be obtained. The gel fraction can be controlled by the content, type, etc. of the reactive groups of the polymer and crosslinking agent in the adhesive composition described later.

[0016] The adhesive material contains a sol component. The sol component is the component eluted in the solvent (ethyl acetate) when the adhesive material is extracted with ethyl acetate at 23°C for 72 hours. And in the differential molecular weight distribution curve of the sol component of the adhesive material, the ratio of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight from 10,000 to 30,000,000 is more than 40%, preferably 50% or more, more preferably 60% or more. When the ratio of the peak area with a molecular weight of 560,000 or more is more than 40%, the adhesive force excellent in adhesive force and vibration resistance in a high-temperature environment is obtained. The differential molecular weight distribution curve is created from the chromatograph obtained by the gel permeation chromatography (hereinafter referred to as "GPC") method. Specifically, the integrated value of the concentration fraction is plotted on the vertical axis and the molecular weight (logarithmic value) is plotted on the horizontal axis to create an integrated molecular weight distribution curve. Next, the slope (differential value) of the curve at each molecular weight is determined. Finally, the differential molecular weight distribution curve is created by plotting the molecular weight (logarithmic value) on the horizontal axis and the differential value on the vertical axis.

[0017] In the differential molecular weight distribution curve of the sol component of the adhesive material, the ratio of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight from 10,000 to 30,000,000 is preferably 95% or less, more preferably 90% or less. When the ratio of the peak area with a molecular weight of 560,000 or more is 95% or less, the followability to deformation is good due to the flexibility of the adhesive material.

[0018] In the differential molecular weight distribution curve of the sol component of the adhesive, the ratio of the peak area with a molecular weight between 100,000 and 560,000 to the peak area with a molecular weight between 10,000 and 30,000,000 is preferably 5% or more, more preferably 10% or more, preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. When the ratio of the peak area with a molecular weight between 100,000 and 560,000 is within the above range, the adhesive strength in high-temperature environments is improved.

[0019] The adhesive has a differential molecular weight distribution curve of the sol component of the adhesive in which the ratio of the peak area with a molecular weight of 10,000 to 100,000 to the peak area with a molecular weight of 10,000 to 30,000,000 is less than 10%, preferably 8% or less, and more preferably 7% or less. The ratio of the peak area with a molecular weight of 10,000 to 100,000 is preferably 0%, but may be greater than 0%. If the ratio of the peak area with a molecular weight of 10,000 to 100,000 is less than 10%, the decrease in adhesive strength at high temperatures due to the plasticizing effect of the sol component can be further suppressed.

[0020] The weight-average molecular weight (Mw) of the sol component is preferably 1 million or more, more preferably 1.1 million or more, even more preferably 1.2 million or more, preferably 3 million or less, more preferably 2.5 million or less, and even more preferably 2.3 million or less. If the weight-average molecular weight is within the above range, the adhesive strength and vibration resistance of the adhesive material in high-temperature environments will be better. The weight-average molecular weight of the sol component is measured by the GPC method.

[0021] The molecular weight distribution (Mw / Mn) of the sol component is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. When the molecular weight distribution is 5.0 or less, the amount of low molecular weight sol components is reduced, which can suppress the decrease in adhesive strength at high temperatures due to the plasticizing effect of the sol component. The molecular weight distribution is determined by (weight-average molecular weight of the polymer (Mw)) / (number-average molecular weight of the polymer (Mn)). The smaller the molecular weight distribution value, the narrower the molecular weight distribution, resulting in a polymer with uniform molecular weights, and the narrowest molecular weight distribution is achieved when the value is 1.0. In other words, the lower limit of the molecular weight distribution is 1.0.

[0022] The adhesive of the present invention can be formed by curing an adhesive composition containing a polymer component and a crosslinking agent. Specifically, the adhesive can be formed by applying the adhesive composition to a substrate or the like and drying it. Furthermore, the coating film may be heated as needed to promote the formation of a crosslinked structure.

[0023] [Adhesive composition] The aforementioned adhesive composition contains a polymer component and a crosslinking agent. The adhesive composition contains, as the polymer component, only (meth)acrylic polymer (P1) (hereinafter sometimes referred to as "polymer (P1)") or (meth)acrylic polymer (P1) and (meth)acrylic polymer (P2) (hereinafter sometimes referred to as "polymer (P2)"). In this specification, the polymer component refers to (meth)acrylic polymer (P1) or (meth)acrylic polymer (P2), and does not include any other polymers.

[0024] (Polymer components) The polymer components (P1) and polymer (P2) contained in the adhesive composition contain 50% by mass or more of structural units derived from (meth)acrylic monomers. Furthermore, the (meth)acrylic polymer may have structures derived from vinyl monomers other than the (meth)acrylic monomers. The monomers constituting the (meth)acrylic polymer will be described below.

[0025] Examples of the (meth)acrylic monomers include (meth)acrylic monomers having a chain alkyl group, (meth)acrylic monomers having a cyclic alkyl group, (meth)acrylic monomers having an aryl group, (meth)acrylic monomers having a hydroxyl group, (meth)acrylic monomers having an alkoxy group, (meth)acrylic monomers having an acidic group, (meth)acrylic monomers having an amino group, (meth)acrylic monomers having an epoxy group, (meth)acrylic monomers having a heterocyclic group, and (meth)acrylic monomers having an amide group.

[0026] Examples of (meth)acrylic monomers having a linear alkyl group include (meth)acrylates having a linear alkyl group and (meth)acrylates having a branched alkyl group. Examples of (meth)acrylates having a linear alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-lauryl (meth)acrylate, and n-stearyl (meth)acrylate. The number of carbon atoms in the linear alkyl group is preferably 1 to 20, more preferably 1 to 15, and even more preferably 1 to 8. Examples of (meth)acrylates having the branched alkyl group include isopropyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, and isodecyl (meth)acrylate. The number of carbon atoms in the branched alkyl group is preferably 3 to 20, more preferably 3 to 12, and even more preferably 3 to 10.

[0027] Examples of the (meth)acrylic monomer having a cyclic alkyl group include (meth)acrylates having a monocyclic cyclic alkyl group and cyclic alkyl (meth)acrylates having a crosslinked ring structure. The cyclic alkyl group may have a chain portion. Examples of the (meth)acrylates having a monocyclic cyclic alkyl group include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, and other cyclic alkyl (meth)acrylate esters. The number of carbon atoms in the monocyclic cyclic alkyl group is preferably 6 to 20, more preferably 6 to 12. Examples of the cyclic alkyl (meth)acrylates having a crosslinked ring structure include bornyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, and norbornyl (meth)acrylate. The number of carbon atoms in the cyclic alkyl group having a cross-linked ring structure is preferably 6 to 20, more preferably 6 to 12.

[0028] Examples of (meth)acrylic monomers having an aryl group include (meth)acrylates having an aryl group. The aryl group may have a chain-like portion, such as an alkylaryl group, an aralkyl group, or an aryloxyalkyl group. That is, examples of (meth)acrylates having an aryl group include compounds in which an aryl group is directly bonded to a (meth)acryloyloxy group, compounds in which an aralkyl group is directly bonded to a (meth)acryloyloxy group, and compounds in which an aryloxyalkyl group is directly bonded to a (meth)acryloyloxy group. Specific examples of (meth)acrylates having an aryl group include phenyl (meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate. The number of carbon atoms in the aryl group is preferably 6 to 12, more preferably 6 to 9.

[0029] Examples of (meth)acrylic monomers having a hydroxyl group include (meth)acrylates having a hydroxyalkyl group, (meth)acrylates having a lactone-modified hydroxyl group, and (meth)acrylates having a polyalkylene glycol group. A hydroxyalkyl group is an alkyl group in which at least one hydrogen atom is substituted with a hydroxyl group. Examples of (meth)acrylates having a hydroxyalkyl group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl (meth)acrylate. The hydroxyalkyl group is preferably linear or branched. The number of carbon atoms in the hydroxyalkyl group is preferably 1 to 10, more preferably 1 to 5.

[0030] Examples of the lactone-modified (meth)acrylate having a hydroxyl group include those obtained by adding a lactone to the hydroxyalkyl group having a (meth)acrylate, with caprolactone being preferred. The amount of lactone added is preferably 1 mol to 10 mol, and more preferably 1 mol to 5 mol. Examples of the lactone-modified (meth)acrylate having a hydroxyl group include a 1 mol adduct of caprolactone to 2-hydroxyethyl (meth)acrylate, a 2 mol adduct of caprolactone to 2-hydroxyethyl (meth)acrylate, a 3 mol adduct of caprolactone to 2-hydroxyethyl (meth)acrylate, a 4 mol adduct of caprolactone to 2-hydroxyethyl (meth)acrylate, a 5 mol adduct of caprolactone to 2-hydroxyethyl (meth)acrylate, and a 10 mol adduct of caprolactone to 2-hydroxyethyl (meth)acrylate.

[0031] Examples of (meth)acrylates having polyalkylene glycol groups include terminal hydroxyl group polyethylene glycol (degree of polymerization = 2-10) mono(meth)acrylate and terminal hydroxyl group polypropylene glycol (degree of polymerization = 2-10) mono(meth)acrylate.

[0032] Examples of (meth)acrylic monomers having an alkoxy group include (meth)acrylates having an alkoxyalkyl group and (meth)acrylates having an alkoxypolyalkylene glycol group. Examples of (meth)acrylates having an alkoxyalkyl group include 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate. Examples of (meth)acrylates having an alkoxypolyalkylene glycol group include polyethylene glycol (degree of polymerization = 2-30) methyl ether (meth)acrylate, polyethylene glycol (degree of polymerization = 2-30) ethyl ether (meth)acrylate, polyethylene glycol (degree of polymerization = 2-30) propyl ether (meth)acrylate, and other polyethylene glycol structural units; polypropylene glycol (degree of polymerization = 2-30) methyl ether (meth)acrylate, polypropylene glycol (degree of polymerization = 2-30) ethyl ether (meth)acrylate, and polypropylene glycol (degree of polymerization = 2-30) propyl ether (meth)acrylate.

[0033] Examples of the acidic groups in the (meth)acrylic monomer having an acidic group include a carboxyl group (-COOH), a sulfonic acid group (-SO3H), a phosphoric acid group (-OPO3H2), a phosphonic acid group (-PO3H2), and a phosphinic acid group (-PO2H2). Examples of (meth)acrylic monomers having an acidic group include (meth)acrylic acid; (meth)acrylates having a carboxyl group such as 2-(meth)acryloyloxyethyl hydrogen succinate, 2-(meth)acryloyloxyethyl hydrogen hexahydrophthalate, 2-(meth)acryloyloxyethyl hydrogen phthalate, and caprolactone adducts of (meth)acrylic acid; and (meth)acrylates having a sulfonic acid group such as ethyl sulfonate (meth)acrylate.

[0034] Examples of (meth)acrylic monomers having an amino group include (meth)acrylates having an amino group. Examples of (meth)acrylates having an amino group include dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, dimethylaminobutyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diethylaminopropyl (meth)acrylate, diethylaminobutyl (meth)acrylate, ethylaminoethyl (meth)acrylate, ethylaminopropyl (meth)acrylate, ethylaminobutyl (meth)acrylate, propylaminoethyl (meth)acrylate, propylaminopropyl (meth)acrylate, and propylaminobutyl (meth)acrylate.

[0035] Examples of (meth)acrylic monomers having epoxy groups include (meth)acrylates having epoxy groups. Examples of (meth)acrylates having epoxy groups include glycidyl (meth)acrylate and (3,4-epoxycyclohexyl)methyl (meth)acrylate.

[0036] Examples of (meth)acrylic monomers having a heterocyclic group include (meth)acrylic monomers having an oxygen-containing heterocyclic group (excluding epoxy groups). Examples of (meth)acrylic monomers having an oxygen-containing heterocyclic group (excluding epoxy groups) include (meth)acrylates having an oxygen-containing heterocyclic group. Examples of (meth)acrylates having an oxygen-containing heterocyclic group include tetrahydrofurfuryl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (5-ethyl-1,3-dioxan-5-yl)methyl (meth)acrylate, 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate, and (1,3-dioxan-5-yl)methyl (meth)acrylate. The oxygen-containing heterocyclic group is preferably a 4-membered to 6-membered ring.

[0037] Examples of (meth)acrylic monomers having an amide group include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N-octyl(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-ethoxymethyl(meth)acrylamide, N-propoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone acrylamide, and 4-(meth)acryloylmorpholine. Although (meth)acrylic monomers having an amide group are (meth)acrylic monomers, they are not included in (meth)acrylates.

[0038] Examples of vinyl monomers other than the (meth)acrylic monomers mentioned above include styrene monomers, vinyl monomers having acidic groups, vinyl monomers containing epoxy groups, vinyl monomers having heterocyclic groups, vinyl amides, nitriles, vinyl carboxylates, α-olefins, dienes, halogenated vinyl monomers, and the like.

[0039] The styrene monomer may be substituted or unsubstituted styrene. Substituents that may be substituted for styrene include alkyl groups, aryl groups, alkoxy groups, aryloxy groups, etc. The styrene monomer also includes fused ring compounds having two or more benzene rings. Examples of the styrene monomer include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 4-methoxystyrene, 4-phenylstyrene, 1-vinylnaphthalene, etc., and preferably styrene or styrene having an alkyl group. The number of carbon atoms in the alkyl group in the styrene having an alkyl group is preferably 1 to 6.

[0040] Examples of the acidic groups in the aforementioned vinyl monomers include carboxyl groups (-COOH), sulfonic acid groups (-SO3H), phosphate groups (-OPO3H2), phosphonic acid groups (-PO3H2), and phosphinic acid groups (-PO2H2). Examples of vinyl monomers having acidic groups include vinyl monomers having carboxyl groups such as crotonic acid, maleic acid, itaconic acid, citraconic acid, and cinnamic acid; vinyl monomers having sulfonic acid groups such as vinyl sulfonic acid and 1-propene-2-sulfonic acid; vinyl monomers having phosphate groups such as vinyl phosphate and isopropenyl phosphate; vinyl monomers having phosphonic acid groups such as vinylphosphonic acid and isopropenylphosphonic acid; and vinyl monomers having phosphinic acid groups such as vinylphosphinic acid (1-methylethenyl)phosphinic acid.

[0041] Examples of vinyl monomers containing the epoxy group include 2-allyloxirane, glycidyl vinyl ether, and 3,4-epoxycyclohexyl vinyl ether.

[0042] Examples of vinyl monomers having a heterocyclic group include vinyl monomers having a nitrogen-containing heterocyclic group and vinyl monomers having a sulfur-containing heterocyclic group. Examples of vinyl monomers having a nitrogen-containing heterocyclic group include vinyl monomers having a 5-membered ring lactam group such as N-vinylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-5-ethylpyrrolidone, N-vinyl-5-propylpyrrolidone, N-vinyl-5-butylpyrrolidone, and 1-(2-propenyl)-2-pyrrolidone; vinyl monomers having a 6-membered ring lactam group such as N-vinylpiperidone; vinyl monomers having a 7-membered ring lactam group such as N-vinylcaprolactam; 2-vinylpyridine, 4-vinylpyridine; and vinylpyrrole. Among these, vinyl monomers having a 5-membered ring lactam group are preferred, and N-vinylpyrrolidone is more preferred. Examples of vinyl monomers having a sulfur-containing heterocyclic group include 2-vinylthiophene.

[0043] Examples of vinylamides include N-vinylformamide and N-vinylacetamide. Examples of nitriles include acrylonitrile and methacrylonitrile. Examples of vinyl carboxylates include vinyl acetate, vinyl pivalate, and vinyl benzoate. Examples of α-olefins include 1-hexene, 1-octene, and 1-decene. Examples of dienes include butadiene, isoprene, 4-methyl-1,4-hexadiene, and 7-methyl-1,6-octadiene. Examples of halogenated vinyl monomers include vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, tetrafluoropropylene, hexafluoropropylene, vinyl chloride, vinylidene chloride, 1-chloro-1-fluoroethylene, 1,2-dichloro-1,2-difluoroethylene, and chlorotrifluoroethylene.

[0044] [(meth)acrylic polymer (P1)] The polymer component contains polymer (P1). Polymer (P1) may be used alone or in combination of two or more types. Polymer (P1) is preferably a (meth)acrylate polymer. A (meth)acrylate polymer is any polymer whose main component (50% by mass or more) is structural units derived from (meth)acrylate, and may contain structural units derived from vinyl monomers other than (meth)acrylate. The content of structural units derived from (meth)acrylate in polymer (P1) is preferably 80% by mass or more, and more preferably 90% by mass or more, per 100% by mass of polymer (P1).

[0045] The polymer (P1) may be a random copolymer, a block copolymer, or a graft copolymer, and is preferably a random copolymer.

[0046] The polymer (P1) contains structural units having a reactive group (R1) for forming a crosslinked structure with the crosslinking agent. The reactive group (R1) is a group that reacts with the epoxy group of the crosslinking agent described later to form a crosslink. Because the polymer (P1) has a reactive group (R1), it can form a crosslink with the crosslinking agent described later.

[0047] The reactive group (R1) is not particularly limited as long as it is a group that can react with the epoxy group of the crosslinking agent, and is preferably an acidic group such as a carboxyl group, sulfonic acid group, phosphoric acid group, phosphonic acid group, or phosphinic acid group, and more preferably a carboxyl group.

[0048] The amount of reactive groups (R1) in the polymer (P1) is preferably 0.05 mmol / g or more, more preferably 0.08 mmol / g or more, even more preferably 0.1 mmol / g or more, preferably 1.5 mmol / g or less, more preferably 1.2 mmol / g or less, and even more preferably 1 mmol / g or less. If the amount of reactive groups (R1) is within the above range, a good three-dimensional network structure can be formed by crosslinking.

[0049] The weight-average molecular weight (Mw) of the polymer (P1) is preferably 300,000 or more, more preferably 500,000 or more, even more preferably 1,000,000 or more, preferably 3,000,000 or less, more preferably 2,800,000 or less, and even more preferably 2,500,000 or less. If the weight-average molecular weight is within the above range, an adhesive with excellent adhesion and vibration resistance in high-temperature environments can be obtained. Furthermore, if the weight-average molecular weight is 300,000 or more, the distance between crosslinking points in three-dimensional crosslinking becomes longer, making it possible to achieve both flexibility and a degree of crosslinking that is excellent in terms of vibration resistance of the adhesive. The weight-average molecular weight of the polymer (P1) is measured by the GPC method.

[0050] The molecular weight distribution (Mw / Mn) of the polymer (P1) is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. When the length (molecular weight) of the polymer chain is moderately large, a large number of reactive groups are present on the polymer surface, which is thought to result in higher reaction efficiency compared to polymers with smaller molecular weights. Therefore, by reducing the molecular weight distribution, the molecular weight of the polymer (sol component) remaining as an uncrosslinked product can be increased. The lower limit of the molecular weight distribution is 1.0.

[0051] The glass transition temperature of the polymer (P1) according to the FOX formula is preferably -70°C or higher, more preferably -60°C or higher, even more preferably -55°C or higher, preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower. If the glass transition temperature according to the FOX formula is -70°C or higher, it provides sufficient cohesive force to the adhesive, improving the durability of the formed adhesive. If it is 0°C or lower, the adhesion of the formed adhesive to the adherend is increased, peeling at low temperatures is suppressed, and durability is improved.

[0052] The glass transition temperature of the (meth)acrylic polymer according to the FOX equation is the value calculated by the following FOX equation (equation (20)). In equation (20), Tg represents the glass transition temperature of the polymer according to the FOX equation (°C). Tgi represents the glass transition temperature according to the FOX equation (°C) when vinyl monomer i forms a homopolymer. Wi represents the mass ratio of vinyl monomer i in the total vinyl monomers forming the copolymer, where ΣWi=1. i is a natural number from 1 to n.

[0053]

number

[0054] Examples of structural units having the reactive group (R1) include structural units derived from the acidic group of an acidic (meth)acrylic monomer and structural units derived from an acidic vinyl monomer, and preferably structural units derived from at least one vinyl monomer selected from the group consisting of (meth)acrylic acid and (meth)acrylate having a carboxyl group.

[0055] The content of the structural unit having the reactive group (R1) is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, even more preferably 1% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 7% by mass or less, out of 100% by mass of all structural units.

[0056] There are no particular restrictions on other structural units of the polymer (P1), but it is preferable that it contains structural units derived from vinyl monomers appropriately selected so that the glass transition temperature of the polymer (P1) is within the above range. More preferably, it contains structural units derived from at least one vinyl monomer selected from the group consisting of (meth)acrylic monomers having a linear alkyl group, (meth)acrylic monomers having a cyclic alkyl group, (meth)acrylic monomers having an aryl group, (meth)acrylic monomers having a hydroxyl group, (meth)acrylic monomers having an alkoxy group, (meth)acrylic monomers having an amino group, (meth)acrylic monomers having a heterocyclic group, (meth)acrylic monomers having an amide group, styrene monomers, and vinyl monomers having a heterocyclic group. Even more preferably, it contains structural units derived from a (meth)acrylic monomer having a linear alkyl group. The content of the other structural units is preferably 93% by mass or less, more preferably 92% by mass or less, and even more preferably 90% by mass or less, out of 100% by mass of all structural units.

[0057] [(meth)acrylic polymer (P2)] The polymer component may contain polymer (P2) in addition to polymer (P1). Polymer (P2) may be used alone or in combination of two or more types. The (meth)acrylic polymer (P2) is preferably a (meth)acrylate polymer. A (meth)acrylate polymer is any polymer whose main component (50% by mass or more) is structural units derived from (meth)acrylate, and may contain structural units derived from vinyl monomers other than (meth)acrylate. The content of structural units derived from (meth)acrylate in polymer (P2) is preferably 80% by mass or more, and more preferably 90% by mass or more, per 100% by mass of polymer (P2).

[0058] The polymer (P2) may be a random copolymer, a block copolymer, or a graft copolymer, and is preferably a random copolymer.

[0059] The weight-average molecular weight (Mw) of the polymer (P2) is preferably 600,000 or more, more preferably 1,000,000 or more, even more preferably 1,500,000 or more, preferably 3,000,000 or less, more preferably 2,900,000 or less, and even more preferably 2,800,000 or less. If the weight-average molecular weight is within the above range, an adhesive with excellent adhesion and vibration resistance in high-temperature environments can be obtained. The weight-average molecular weight of the polymer (P2) is measured by the GPC method.

[0060] The molecular weight distribution (Mw / Mn) of the polymer (P2) is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. If the molecular weight distribution (Mw / Mn) is 5.0 or less, the amount of low molecular weight sol components can be reduced. The lower limit of the molecular weight distribution is 1.0.

[0061] The glass transition temperature of the polymer (P2) according to the FOX formula is preferably -70°C or higher, more preferably -60°C or higher, even more preferably -50°C or higher, preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower. If the glass transition temperature according to the FOX formula is -70°C or higher, it provides sufficient cohesive force to the adhesive, improving the durability of the formed adhesive. If it is 0°C or lower, the adhesion of the formed adhesive to the adherend is increased, peeling at low temperatures is suppressed, and durability is improved.

[0062] The polymer (P2) preferably contains substantially no structural units having a reactive group (R1). When the polymer (P2) contains substantially no reactive group (R1), the amount of reactive group (R1) in the polymer (P2) is 0.01 mmol / g or less, preferably 0.005 mmol / g or less, and more preferably 0.001 mmol / g or less.

[0063] The polymer (P2) preferably contains structural units having heterocyclic groups and / or structural units having amide groups. The inclusion of heterocyclic or amide group structural units in the polymer (P2) improves cohesiveness and further enhances adhesiveness.

[0064] Examples of the aforementioned heterocyclic groups include nitrogen-containing heterocyclic groups, oxygen-containing heterocyclic groups (excluding epoxy groups), and sulfur-containing heterocyclic groups.

[0065] The aforementioned structural unit having a heterocyclic group may be a structural unit derived from a (meth)acrylic monomer, or a structural unit derived from a vinyl monomer other than a (meth)acrylic monomer. Preferred structural units having a heterocyclic group include structural units derived from a (meth)acrylic monomer having an oxygen-containing heterocyclic group (excluding epoxy groups), structural units derived from a vinyl monomer having a nitrogen-containing heterocyclic group, and structural units derived from a vinyl monomer having a sulfur-containing heterocyclic group. Among these, structural units derived from a (meth)acrylic monomer having an oxygen-containing heterocyclic group of 4-membered to 6-membered rings, and structural units derived from a vinyl monomer having a lactam group of 5-membered to 7-membered rings are more preferred. Furthermore, for the purpose of further improving adhesion in high-temperature environments, structural units derived from a vinyl monomer having a nitrogen-containing heterocyclic group are preferred.

[0066] The structural unit having the amide group may be a structural unit derived from a (meth)acrylic monomer or a structural unit derived from a vinyl monomer other than a (meth)acrylic monomer, but it is preferably a structural unit derived from a (meth)acrylic monomer having an amide group, and more preferably a structural unit derived from 4-(meth)acryloylmorpholine.

[0067] When the polymer (P2) contains structural units having heterocyclic groups and / or structural units having amide groups, the total content of structural units having heterocyclic groups and structural units having amide groups in 100% by mass of polymer (P2) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 7% by mass or less. If the total content of structural units having heterocyclic groups and structural units having amide groups is within the above range, the effect of improving adhesion due to improved cohesiveness will be further improved.

[0068] There are no particular restrictions on other structural units of the polymer (P2), but it is preferable that it contains structural units derived from vinyl monomers appropriately selected so that the glass transition temperature of the polymer (P2) is within the above range, and more preferably it contains structural units derived from at least one vinyl monomer selected from the group consisting of (meth)acrylic monomers having a linear alkyl group, (meth)acrylic monomers having a cyclic alkyl group, (meth)acrylic monomers having an aryl group, (meth)acrylic monomers having a hydroxyl group, (meth)acrylic monomers having an alkoxy group, (meth)acrylic monomers having an amino group, and styrene monomers, and even more preferably it contains (meth)acrylic monomers having a linear alkyl group.

[0069] The content of the other structural units is preferably 93% by mass or less, more preferably 92% by mass or less, and even more preferably 90% by mass or less, out of 100% by mass of all structural units.

[0070] The content of polymer components in 100% by mass of the solid content of the adhesive composition is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 99.9% by mass or more. The solid content of the adhesive composition refers to the components of the adhesive composition other than the solvent.

[0071] When the polymer component contains polymer (P1) and polymer (P2), the mass ratio of polymer (P2) to polymer (polymer (P2) / polymer (P1)) is preferably 0.5 or more, more preferably 0.8 or more, even more preferably 1.5 or more, preferably 5 or less, more preferably 4 or less, and even more preferably 3.5 or less. If the mass ratio (polymer (P2) / polymer (P1)) is 0.5 or more, an adhesive strength with even better vibration resistance in high-temperature environments can be obtained, and if it is 5 or less, an adhesive material with even better adhesive strength in high-temperature environments can be obtained.

[0072] [Method for producing polymers] The polymer (P1) and the polymer (P2) can be produced by polymerizing the monomer using a conventionally known polymerization method.

[0073] Examples of polymerization methods include radical polymerization (also called free radical polymerization), cationic polymerization, anionic polymerization, and living polymerization. Among these, living polymerization is preferred from the viewpoint of precise control of molecular weight distribution and production of polymers with a uniform composition. In other words, polymers (P1) and polymers (P2) are preferably polymerized by living polymerization.

[0074] Free radical polymerization can be carried out using conventionally known methods. Polymerization initiators used in free radical polymerization include azo polymerization initiators and peroxide polymerization initiators. Examples of azo polymerization initiators include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(1-cyclohexanecarbonitride), dimethyl-2,2'-azobisisobutyrate, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and 2,2'-azobis(N-butyl-2-methylpropionamide).

[0075] The polymerization reaction can be carried out without a solvent, but it may also be carried out by stirring a mixture of vinyl monomers using an aprotic or protic solvent commonly used in radical polymerization. Examples of aprotic solvents include acetonitrile, methyl ethyl ketone, anisole, benzene, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, tetrahydrofuran (THF), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), acetone, dioxane, chloroform, and carbon tetrachloride. Examples of protic solvents include water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol, hexafluoroisopropanol, and diacetone alcohol. The solvent may be used alone or in combination of two or more.

[0076] The amount of solvent used can be adjusted as appropriate; for example, per 1 g of vinyl monomer, it is preferably 0.01 ml to 50 ml, more preferably 0.05 ml to 10 ml, and even more preferably 0.1 ml to 1 ml.

[0077] The reaction temperature and reaction time can be adjusted as appropriate depending on the molecular weight or molecular weight distribution of the resulting polymer, but typically, the reaction is carried out at 0°C to 150°C for 1 minute to 100 hours with stirring. At this time, the reaction is usually carried out at atmospheric pressure, but it may also be carried out under increased or decreased pressure. After the polymerization reaction is complete, the target polymer can be separated from the resulting reaction mixture by removing the solvent used, residual vinyl monomer, etc., using conventional separation and purification methods.

[0078] Living polymerization is a type of polymer polymerization in which, among the four elementary reactions in chain polymerization (initiation, growth, termination, and chain transfer), side reactions such as termination and chain transfer are substantially absent, and the reaction sites (polymerization growth ends) remain uninactivated, allowing vinyl monomers to react and polymer chains to grow. As a result, polymers with a small molecular weight distribution and a uniform composition can be produced. Living polymerization includes living radical polymerization, living anionic polymerization, and living cationic polymerization. Among these, living radical polymerization is preferred from the viewpoint of ease of polymerization. Furthermore, living radical polymerization is also preferred because it maintains the ease of use and versatility of free radical polymerization while allowing for precise control of molecular weight distribution and easy production of polymers with a uniform composition.

[0079] Living radical polymerization includes methods that utilize compounds capable of generating nitroxide radicals, depending on the method used to stabilize the polymerization growth ends (nitroxide method; NMP method); methods that use metal complexes such as copper and ruthenium, with halogenated compounds acting as polymerization initiators and polymerizing them in a living manner (ATRP method); methods that use dithiocarboxylic acid esters or xantate compounds (RAFT method); methods that use organotellurium compounds (TERP method); methods that use organioidone compounds (ITP method); and methods that use iodine compounds as polymerization initiators and organic compounds such as phosphorus compounds, nitrogen compounds, oxygen compounds, or hydrocarbons as catalysts (reversible transfer catalytic polymerization; RTCP method, reversible catalyst-mediated polymerization; RCMP method). Among these methods, the TERP method is preferred from the viewpoint of the diversity of monomers that can be used, molecular weight control in the polymer range, uniform composition, and coloration.

[0080] The TERP method is a method for polymerizing radical polymerizable compounds (vinyl monomers) using an organotellurium compound as a chain transfer agent, and is described, for example, in International Publication Nos. 2004 / 14848, 2004 / 14962, 2004 / 072126, 2004 / 096870, and 2020 / 116144.

[0081] Specific polymerization methods of the TERP method include the following (a) to (d). (a) A method of polymerizing a vinyl monomer using an organic tellurium compound represented by the formula (T1). (b) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (T1) and an azo-based polymerization initiator. (c) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (T1) and an organic ditelluride compound represented by the formula (T2). (d) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (T1), an azo-based polymerization initiator, and an organic ditelluride compound represented by the formula (T2).

[0082] R t1 -Te-CR t2 R t3 R t4 (T1) R t1 -Te-Te-R t1 (T2) [In the formula (T1) and the formula (T2), R t1 represents an alkyl group, an aryl group, or an aromatic heterocyclic group having 1 to 8 carbon atoms. R t2 and R t3 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R t4 represents an alkyl group, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amide group, an oxycarbonyl group, a cyano group, an allyl group, or a propargyl group.] ​​​ Specific examples of organic diterlide compounds represented by formula (T2) include dimethyl diterlide and dibutyl diterlide.

[0084] Any azo polymerization initiator used in normal radical polymerization can be used without particular restrictions, such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(1-cyclohexanecarbonitride), dimethyl-2,2'-azobisisobutyrate, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and 2,2'-azobis(N-butyl-2-methylpropionamide).

[0085] The polymerization step involves mixing a vinyl monomer, an organic tellurium compound of formula (T1), and, depending on the type of vinyl monomer, an azo polymerization initiator and / or an organic diterlide compound of formula (T2) in a container purged with an inert gas, for purposes such as promoting the reaction, controlling the molecular weight and molecular weight distribution. Examples of inert gases used include nitrogen, argon, and helium. Argon and nitrogen are preferred. The amount of vinyl monomer used in (a), (b), (c), and (d) above may be appropriately adjusted depending on the physical properties of the desired polymer.

[0086] The polymerization reaction can be carried out without a solvent, but it may also be carried out using an aprotic or protic solvent commonly used in radical polymerization, while stirring the mixture. Examples of aprotic solvents include acetonitrile, methyl ethyl ketone, anisole, benzene, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, acetone, dioxane, chloroform, and carbon tetrachloride. Examples of the protic solvent include water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol, hexafluoroisopropanol, and diacetone alcohol. The solvent may be used alone or in combination of two or more. The amount of solvent used can be adjusted as appropriate; for example, 0.01 ml to 50 ml per 1 g of vinyl monomer is preferred. In the polymerization reaction, in addition to the solvent, a surfactant and / or dispersant may also be used.

[0087] The reaction temperature and reaction time can be adjusted as appropriate depending on the molecular weight or molecular weight distribution of the resulting polymer, but typically, the reaction is carried out at 0°C to 150°C for 1 minute to 100 hours with stirring. The reaction is usually carried out at atmospheric pressure, but it may also be carried out under increased or decreased pressure. The polymerization reaction may also be carried out under light irradiation. After the polymerization reaction is complete, the target polymer can be separated from the resulting reaction mixture by removing the solvent and residual vinyl monomer using conventional separation and purification methods.

[0088] The growth ends of the polymer obtained by the polymerization reaction are derived from the tellurium compound -TeR t1 (In the formula, R t1 The same applies as above.) This is the form in which the tellurium atoms are removed from the polymerization growth end by handling in air after the polymerization reaction is complete, but some tellurium atoms may remain. Polymers with tellurium atoms remaining at the ends may be discolored or have poor thermal stability, so it is preferable to remove the tellurium atoms. Methods for removing tellurium atoms include radical reduction methods; adsorption methods using activated carbon, etc.; and adsorption methods using ion exchange resins, etc. These methods can also be used in combination. The other end of the polymer obtained by the polymerization reaction (the end opposite to the polymerization growth end) is -CR derived from the tellurium compound. t2 R t3 R t4 (In the formula, R t2 , R t3 and R t4 R in equation (T1) t2 , R t3 and R t4It is the same as ( ). ) It is in the form of . Therefore, polymers obtained by the TERP method do not have substituents containing sulfur atoms at their ends.

[0089] (Crosslinking agent) The adhesive composition contains a crosslinking agent. The crosslinking agent introduces a crosslinked structure into the cured product of the adhesive composition. The crosslinked structure is a crosslinked structure formed from the molecular chains of polymer (P1) and the crosslinking agent, and may include a crosslinked structure formed solely from the crosslinking agent, or a crosslinked structure formed from the molecular chains of polymers other than polymer (P1) and the crosslinking agent, as long as it does not hinder the effects of the present invention.

[0090] (Epoxy crosslinking agent) The crosslinking agent contains an epoxy crosslinking agent. The epoxy crosslinking agent is preferably a compound having two or more epoxy groups in one molecule. The epoxy crosslinking agent may be used alone or in combination of two or more types. Since epoxy groups are highly reactive with acidic groups, when forming a crosslinked structure between the polymer molecular chain and the epoxy crosslinking agent, an acidic group is preferred as the reactive group (R1) of the polymer.

[0091] The average number of epoxy groups in one molecule of the epoxy crosslinking agent is 2 or more, preferably 8 or less, and more preferably 6 or less.

[0092] The molecular weight of the epoxy crosslinking agent is preferably 200 or more, more preferably 250 or more, even more preferably 300 or more, preferably 1500 or less, more preferably 1000 or less, and even more preferably 700 or less.

[0093] The epoxy group content of the epoxy crosslinking agent is preferably 1.5 mmol / g or more, more preferably 2.0 mmol / g or more, preferably 10 mmol / g or less, and more preferably 8 mmol / g or less. By setting the epoxy group content of the epoxy crosslinking agent within the above range, it becomes possible to design the adhesive strength to a suitable range.

[0094] Examples of the epoxy crosslinking agent include aliphatic epoxy compounds, alicyclic epoxy compounds, aromatic epoxy compounds, and heterocyclic epoxy compounds.

[0095] Examples of the aliphatic epoxy compound include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane polyglycidyl ether, diglycidylamine, neopentyl glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, glycerin diglycidyl ether, and lycerin. Examples include triglycidyl ethers, polyglycerol polyglycidyl ethers, and diglycidyl adipate esters.

[0096] Examples of the alicyclic epoxy compound include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, and N,N,N',N'-tetraglycidyl-m-xylylenediamine.

[0097] Examples of the aromatic epoxy compounds include bisphenol A epichlorohydrin type epoxy resins, diglycidylaniline, o-phthalate diglycidyl esters, resorcinol diglycidyl ethers, and bisphenol-S-diglycidyl ethers.

[0098] Examples of the aforementioned heterocyclic epoxy compounds include triglycidyl-tris(2-hydroxyethyl) isocyanurate, 1,3,5-tris-(2,3-epoxybutyl)-isocyanurate, 1,3,5-tris-(3,4-epoxybutyl)-isocyanurate, 1,3,5-tris-(4,5-epoxypentyl)-isocyanurate, and sorbitan polyglycidyl ether.

[0099] The epoxy crosslinking agent is preferably a compound having two epoxy groups in one molecule (a difunctional epoxy crosslinking agent), a compound having three epoxy groups in one molecule (a trifunctional epoxy crosslinking agent), or a compound having four epoxy groups in one molecule (a tetrafunctional epoxy crosslinking agent). If the crosslinking agent is a difunctional epoxy crosslinking agent, a trifunctional epoxy crosslinking agent, or a tetrafunctional epoxy crosslinking agent, crosslinking over time due to unreacted reactive groups is suppressed, making it possible to produce a stable adhesive.

[0100] The content of the epoxy crosslinking agent in the adhesive composition is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.008 parts by mass or more, preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and even more preferably 0.3 parts by mass or less, per 100 parts by mass of the total polymer components.

[0101] When the polymer component contains only polymer (P1), the content of the epoxy crosslinking agent in the adhesive composition is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.008 parts by mass or more, preferably 0.1 parts by mass or less, more preferably 0.05 parts by mass or less, and even more preferably 0.03 parts by mass or less, per 100 parts by mass of polymer (P1).

[0102] When the polymer component contains polymer (P1) and polymer (P2), the content of the epoxy crosslinking agent in the adhesive composition is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, even more preferably 0.05 parts by mass or more, preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and even more preferably 0.3 parts by mass or less, based on 100 parts by mass of the total of polymer (P1) and polymer (P2).

[0103] If the content of the epoxy crosslinking agent is within the aforementioned range, it becomes possible to design the sol component to a suitable range.

[0104] The molar ratio ((R1) / epoxy group) of the reactive group (R1) of the polymer to the epoxy group of the epoxy crosslinking agent is preferably 1 or more, more preferably 3 or more, even more preferably 5 or more, preferably 1000 or less, more preferably 600 or less, and even more preferably 300 or less.

[0105] When the polymer component contains only polymer (P1), the molar ratio of reactive groups (R1) of the polymer to epoxy groups of the epoxy crosslinking agent ((R1) / epoxy groups) is preferably 50 or more, more preferably 80 or more, even more preferably 100 or more, preferably 1000 or less, more preferably 600 or less, and even more preferably 300 or less.

[0106] When the polymer component includes polymer (P1) and polymer (P2), the molar ratio ((R1) / epoxy group) of the reactive group (R1) of the polymer to the epoxy group of the epoxy crosslinking agent is preferably 1 or more, more preferably 3 or more, even more preferably 5 or more, preferably 200 or less, more preferably 160 or less, and even more preferably 90 or less.

[0107] If the molar ratio ((R1) / epoxy group) is within the aforementioned range, it becomes possible to design the sol component to a suitable range.

[0108] (Other crosslinking agents) The adhesive composition may contain only the epoxy crosslinking agent, or it may contain other crosslinking agents other than the epoxy crosslinking agent, as long as they do not impair the effects of the present invention.

[0109] The aforementioned other crosslinking agents have two or more reactive groups (R2) in their molecules. The reactive groups (R2) are functional groups that bond with other reactive groups (R2) to form a crosslinked structure, or functional groups that react with the reactive groups of the polymer component.

[0110] Examples of reactive groups (R2) include hydroxyl groups, carboxyl groups, vinyl groups (ethylenically unsaturated groups), amino groups, isocyanate groups, alidiline groups, carbodiimide groups, and oxazoline groups.

[0111] Other crosslinking agents include isocyanate-based crosslinking agents, radical polymerization-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, carbodiimide-based crosslinking agents, metal chelate-based crosslinking agents, melamine resin-based crosslinking agents, urea resin-based crosslinking agents, and radical polymerization-based crosslinking agents. One of these may be used alone, or two or more may be used in combination.

[0112] The total content of the crosslinking agent in the adhesive composition is preferably 0.001 parts by mass or more, more preferably 0.05 parts by mass or more, preferably 0.5 parts by mass or less, and more preferably 0.4 parts by mass or less, per 100 parts by mass of the total polymer components. If the crosslinking agent content is within the above range, it becomes possible to design the sol component to a suitable range.

[0113] (Isocyanate-based crosslinking agent) The isocyanate-based crosslinking agent is preferably a compound having two or more isocyanate groups (including isocyanate-regenerating functional groups in which the isocyanate groups are temporarily protected by a blocking agent or quantification, etc.) in one molecule as the reactive group (R2). The isocyanate-based crosslinking agent may be used alone or in combination of two or more types. Since isocyanate groups are highly reactive with hydroxyl groups, when forming a crosslinked structure between the polymer molecular chain and the isocyanate-based crosslinking agent, hydroxyl groups are preferred as the reactive groups of the polymer.

[0114] Examples of the isocyanate-based crosslinking agents include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, adducts of these with various polyols, and polyisocyanates polyfunctionalized by isocyanurate bonds, biuret bonds, allophanate bonds, etc.

[0115] Specifically, examples include compounds having two isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate groups are temporarily protected by a blocking agent or quantification, etc.) in one molecule (bifunctional isocyanate crosslinking agents), compounds having three isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate groups are temporarily protected by a blocking agent or quantification, etc.) in one molecule (trifunctional isocyanate crosslinking agents), compounds having six isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate groups are temporarily protected by a blocking agent or quantification, etc.) in one molecule (hexafunctional isocyanate crosslinking agents), and so on.

[0116] Examples of the aforementioned bifunctional isocyanate crosslinking agents include diisocyanate compounds such as aliphatic diisocyanate compounds, alicyclic diisocyanate compounds, and aromatic diisocyanate compounds. Additives of these diisocyanate compounds with diol compounds can also be used. Diisocyanate compounds are compounds represented by the general formula "O=C=NXN=C=O" (where X is a divalent aliphatic group, a divalent alicyclic group, a divalent aromatic group, etc.). Diol compounds are compounds represented by the general formula "HO-Y-OH" (where Y is a divalent aliphatic group, a divalent alicyclic group, a divalent aromatic group, etc.).

[0117] Examples of the aliphatic diisocyanate compounds include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate. Among these, aliphatic diisocyanate compounds having 4 to 30 carbon atoms are preferred, and aliphatic diisocyanate compounds having 4 to 10 carbon atoms are more preferred.

[0118] Examples of the aforementioned alicyclic diisocyanate compounds include isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate. Among these, alicyclic diisocyanate compounds having 7 to 30 carbon atoms are preferred.

[0119] Examples of the aforementioned aromatic diisocyanate compounds include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, and diphenylpropane diisocyanate, with aromatic diisocyanate compounds having 8 to 30 carbon atoms being preferred.

[0120] Examples of the aforementioned diol compounds include aliphatic diol compounds such as 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, polyethylene glycol, and polypropylene glycol, among which aliphatic diol compounds having 3 to 10 carbon atoms are preferred.

[0121] Examples of the three-functional isocyanate crosslinking agent and the six-functional isocyanate crosslinking agent include the adduct form of the diisocyanate compound, the biuret form of the diisocyanate compound, and the isocyanurate form of the diisocyanate compound (cyclic polymers of diisocyanate compounds).

[0122] The isocyanate crosslinking agent is preferably a bifunctional isocyanate crosslinking agent selected from the group consisting of aliphatic diisocyanate compounds and adducts of aliphatic diol compounds; or a trifunctional or hexafunctional isocyanate crosslinking agent selected from the group consisting of adducts of aliphatic diisocyanate compounds, biurets of aliphatic diisocyanate compounds, and isocyanurates of aliphatic diisocyanate compounds. If the crosslinking agent is a trifunctional or hexafunctional aliphatic isocyanate crosslinking agent, crosslinking over time due to unreacted reactive groups is suppressed, making it possible to produce a stable adhesive.

[0123] (Radical polymerization crosslinking agent) The radical polymerization crosslinking agent is preferably a compound having two or more ethylenically unsaturated groups as the reactive group (R2) in one molecule. The radical polymerization crosslinking agent may be used alone or in combination of two or more types. Since ethylenically unsaturated groups have high reactivity with similar functional groups, when forming a crosslinked structure between the polymer molecular chain and the radical polymerization crosslinking agent, ethylenically unsaturated groups are preferred as the reactive groups of the polymer.

[0124] The number of ethylenically unsaturated groups in one molecule of the radical polymerization crosslinking agent is preferably two or more, preferably four or less, and more preferably three or less. Examples of the radical polymerization crosslinking agent include compounds having two or more (meth)acryloyl groups, and polyfunctional monomers and polyfunctional oligomers are preferred.

[0125] Examples of compounds having two or more (meth)acryloyl groups include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, isocyanurate ethylene oxide modified tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, and urethane(meth)acrylate.

[0126] (Other additives) The aforementioned adhesive composition can be used by combining it with other additives in addition to polymer components (polymer (P1), polymer (P2)) and crosslinking agents. Examples of other additives include crosslinking accelerators, crosslinking retarders, tackifiers, photopolymerization initiators, silane coupling agents, plasticizers, softeners, release aids, dyes, pigments, fluorescent whitening agents, antistatic agents, wetting agents, surfactants, thickeners, antifungal agents, preservatives, oxygen absorbers, ultraviolet absorbers, antioxidants, near-infrared absorbers, water-soluble quenchers, fragrances, metal deactivators, nucleating agents, alkylating agents, flame retardants, lubricants, and processing aids. These are selected and combined as appropriate depending on the application and intended use of the adhesive.

[0127] (Crosslinking promoter) The adhesive composition may be used with a crosslinking accelerator added as needed. Examples of crosslinking accelerators include organotin compounds and metal chelate compounds. The crosslinking accelerator may be used alone or in combination of two or more types.

[0128] Examples of the organotin compounds include dibutyltin dilaurate, dioctyolustin dilaurylate, and dibutyltin dioctylate. The metal chelate compound is a complex in which ligands having two or more coordinating atoms form a ring and are bonded to a central metal.

[0129] The content of the crosslinking accelerator in the adhesive composition is preferably 0.01 to 0.5 parts by mass, more preferably 0.02 to 0.4 parts by mass, and even more preferably 0.04 to 0.3 parts by mass, per 100 parts by mass of the polymer component. By setting the content of the crosslinking accelerator within the above range, it is possible to obtain an excellent crosslinking promoting effect.

[0130] (Crosslinking retarder) The adhesive composition may be used with a crosslinking retarder added as needed. The crosslinking retarder is a compound that can suppress an excessive increase in the viscosity of the adhesive composition by blocking the functional groups of the crosslinking agent in the adhesive composition containing the crosslinking agent. Examples of crosslinking retarders include β-diketones such as acetylacetone, hexane-2,4-dione, heptane-2,4-dione, and octane-2,4-dione; β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate; and benzoylacetone. The crosslinking retarder is preferably one that can act as a chelating agent, and β-diketones and β-ketoesters are preferred.

[0131] The amount of the crosslinking retarder that can be incorporated into the adhesive composition is preferably 0.1 to 4.0 parts by mass, more preferably 0.2 to 3.0 parts by mass, and even more preferably 0.5 to 1.5 parts by mass, per 100 parts by mass of the polymer component. If the amount of the crosslinking retarder is within the above range, after incorporating the crosslinking agent into the adhesive composition, it is possible to suppress excessive viscosity increase and gelation of the adhesive composition and extend the storage stability (pot life) of the adhesive composition.

[0132] (Photopolymerization initiator) When a radical polymerization crosslinking agent is used as the crosslinking agent, it is preferable to incorporate a photopolymerization initiator into the adhesive composition and irradiate it with active energy rays. By incorporating a photopolymerization initiator, the reaction during active energy ray irradiation can be accelerated. The photopolymerization initiator is not particularly limited as long as it generates radicals upon the action of light, and examples include photopolymerization initiators such as acetophenones, benzoins, thioxanthones, and acylphosphine oxides. These photopolymerization initiators can be used alone or in combination of two or more. Among these photopolymerization initiators, hydrogen abstraction type benzophenones and intramolecular cleavage type acetophenones are preferred because they can efficiently crosslink intermolecularly or intramolecularly.

[0133] When a photopolymerization initiator is incorporated into the adhesive composition, the amount of the photopolymerization initiator is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 2 parts by mass, per 100 parts by mass of the polymer component.

[0134] Furthermore, the adhesive composition may contain an auxiliary agent for photopolymerization. The auxiliary agents may include triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoate ethyl, 4-dimethylaminobenzoate (n-butoxy)ethyl, 4-dimethylaminobenzoate isoamyl, 4-dimethylaminobenzoate 2-ethylhexyl, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and others. These auxiliary agents may be used individually or in combination of two or more.

[0135] (Silane coupling agent) The adhesive composition may be used with a silane coupling agent as needed. Examples of the silane coupling agent include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatetopropyltriethoxysilane.

[0136] The amount of silane coupling agent that can be incorporated into the adhesive composition is preferably 0.01 to 1 part by mass, more preferably 0.15 to 0.8 parts by mass, and even more preferably 0.02 to 0.6 parts by mass, per 100 parts by mass of the polymer component. By setting the amount of silane coupling agent within this range, the water resistance at the interface when the adhesive is applied to a hydrophilic substrate such as glass can be improved.

[0137] (Method for manufacturing adhesive composition) The adhesive composition can be manufactured by mixing polymer components, a crosslinking agent, and, if necessary, other additives. The adhesive composition may contain a solvent derived from the manufacture of the polymer, or it may be a solution diluted with an appropriate solvent to achieve a viscosity suitable for forming an adhesive layer.

[0138] Examples of the aforementioned solvents include aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; cellosolve solvents such as ethyl cellosolve; and glycol ether solvents such as propylene glycol monomethyl ether. These solvents may be used individually or in mixtures of two or more.

[0139] The amount of solvent used can be adjusted as appropriate so that the adhesive composition has a viscosity suitable for coating, and there are no particular restrictions, but from the viewpoint of coating properties, 1% to 90% by mass is preferred, more preferably 10% to 80% by mass, and even more preferably 20% to 70% by mass.

[0140] (Adhesive material use) The adhesive material of the present invention exhibits excellent adhesive strength and vibration resistance in high-temperature environments. Therefore, it can be used as an adhesive for automotive components that are exposed to high-temperature environments and vibrations during operation, such as electronic equipment, interior materials, and exterior materials used inside automobiles. Furthermore, it can be used as an adhesive for optical components such as image display devices.

[0141] <Adhesive film> The adhesive film of the present invention is characterized in that the adhesive layer is formed from the adhesive material. The adhesive film preferably has a form comprising a base film and an adhesive layer formed on at least one surface of the base film; or a form comprising two release films and an adhesive layer sandwiched between the release films so as to be in contact with the release surfaces of the two release films.

[0142] (Adhesive layer) The adhesive layer is formed from the adhesive material. The thickness of the adhesive layer is preferably 2 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, from the viewpoint of ensuring sufficient adhesion to the adherend. Furthermore, the thickness of the adhesive layer is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less, from the viewpoint of suppressing the overflow of the adhesive layer.

[0143] (Base film) The aforementioned base film is a film member that supports the adhesive layer and can be appropriately selected and used depending on the application of the adhesive film. Examples of base films include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); acrylic resins such as polymethyl methacrylate (PMMA); and films composed of plastic materials such as polycarbonate, triacetyl cerose (TAC), polystyrene, polysulfone, polyethersulfone, polyphenylenesulfone, polyphenylene sulfide, polyetheretherketone, cycloolefin polymer, cycloolefin copolymer, fluoropolymer, polyarylate, polyetherimide, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, and ethylene-propylene copolymer. These plastic materials can be used individually or in combination of two or more. Among these, PET is preferred in terms of its excellent mechanical strength and dimensional stability. Polyimide is also preferred in terms of its excellent heat resistance. In other words, PET film (especially biaxially oriented PET film) and polyimide film are preferred as the base film.

[0144] The thickness of the base film is not particularly limited and can be selected as appropriate, but is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. If the thickness is 5 μm or more, the mechanical strength of the base film is improved, and tearing of the film during peeling is further suppressed. Also, if the thickness of the base film is 200 μm or less, it is possible to prevent the film itself from becoming expensive.

[0145] The aforementioned base film may be surface-treated on one or both sides, if desired, by oxidation, embossing, or other methods, in order to improve adhesion with the layer provided on its surface. Examples of oxidation methods include corona discharge treatment, plasma treatment, chromic acid treatment (wet), flame treatment, hot air treatment, and ozone / ultraviolet irradiation treatment. Examples of embossing methods include sandblasting and solvent treatment. These surface treatment methods are appropriately selected depending on the type of base film, but corona discharge treatment is generally preferred in terms of effectiveness and ease of operation. Furthermore, a base film that has been primer-treated on one or both sides can also be used.

[0146] (Release film) The adhesive film may have a release film (separator) on the surface of the adhesive layer until use. Alternatively, without using a separate release film, the release layer may be provided on the surface of the base film opposite to the adhesive layer lamination surface, and the film may be wound in a roll shape or laminated in layers such that the exposed side of the adhesive layer is in contact with the surface of the release layer. The release film is used as a protective material for the adhesive layer and is peeled off when the adhesive film of the present invention is applied to an object.

[0147] Examples of the release film include paper such as glassine paper, coated paper, and laminated paper, as well as various plastic films coated with a release agent such as silicone resin. The plastic film used for the release film can be any of the materials listed as the base film. There are no particular restrictions on the thickness of the release film, but it is typically 10 μm to 150 μm.

[0148] (Method for forming an adhesive layer) The method for forming the adhesive layer is not particularly limited, and examples include applying an adhesive composition as in (1) and (2) below and curing it by drying and heat treatment. (1) A method of applying an adhesive composition to one or both sides of a base film using various coating equipment, drying and heat treatment, and curing as necessary. (2) A method of applying an adhesive composition to the release surface of a release film that has been treated to release on its surface using various coating devices, drying and heat-treating it, transferring it to one or both sides of a base film, and then curing it as necessary.

[0149] Examples of the coating apparatus include reverse roll coaters, gravure coaters, forward roll coaters, knife coaters, wire bar coaters, doctor blade coaters, slot die coaters, curtain coaters, and dip coaters.

[0150] The drying and heating process is not particularly limited as long as it removes the solvent used in the adhesive composition and allows it to harden, but it is preferable to carry it out at a temperature of 60°C to 150°C for 20 to 300 seconds. In particular, the heating temperature is preferably 100°C to 130°C. Means of drying include hot air, near-infrared rays, infrared rays, and high-frequency waves. The curing conditions can be, for example, 23°C to 60°C for 3 to 7 days. The crosslinking reaction is completed by drying and removing the solvent and curing, and an adhesive layer is formed. [Examples]

[0151] The present invention will be described in more detail below based on specific examples. The present invention is not limited in any way to the following examples, and can be implemented with appropriate modifications without changing the essence of the invention. The polymerization rate, weight-average molecular weight, and molecular weight distribution of the copolymer were evaluated according to the method described below.

[0152] The meanings of the abbreviations are as follows: BTEE: Ethyl 2-methyl-2-n-butylteranyl propionate AIBN: 2,2'-Azobis(isobutyronitrile) EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate MA: Methyl acrylate AA: Acrylic acid VP:N-vinyl-2-pyrrolidone AcOEt: Ethyl acetate

[0153] (Polymerization rate) Using a nuclear magnetic resonance (NMR) spectroscopy system (Bruker BioSpin, model: AVANCE500 (frequency 500MHz)), 1 ¹H-NMR was measured (solvent: CDCl3, internal standard: tetramethylsilane). The integral ratio of the monomer-derived peaks and polymer-derived peaks in the obtained NMR spectrum was determined to calculate the monomer polymerization rate.

[0154] (Weight-average molecular weight and molecular weight distribution) Gel permeation chromatography (GPC) was performed using a high-performance liquid chromatograph (Tosoh, model HLC-8320GPC). Two TSKgel Super HZM-H columns (Tosoh) were used, tetrahydrofuran solution was used as the mobile phase, and a differential refractometer was used as the detector. The measurement conditions were a column temperature of 40°C, a sample concentration of 0.5 mg / mL, a sample injection volume of 10 μL, and a flow rate of 0.6 mL / min. Calibration curves were created using polystyrene (molecular weights 9,840,000, 5,480,000, 2,890,000, 1,090,000, 775,000, 427,000, 190,000, 96,400, 37,900, 10,200, 2,630) as standard substances, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured. The molecular weight distribution (Mw / Mn) was calculated from these measurements.

[0155] (Adhesive layer thickness) The total thickness of the adhesive sheet was measured using a thickness measuring instrument (TH-104, manufactured by Tester Industries), and the thickness of the adhesive material was determined by subtracting the thickness of the release liner from this total thickness.

[0156] (Gel fraction) The mass M2 of a wire mesh (400 mesh) cut to a size of 50 mm in width and 120 mm in length was measured. 80 mg to 120 mg of the adhesive layer (adhesive material) constituting the adhesive film was taken and its mass M1 was measured. Test specimens were prepared by wrapping the adhesive material in wire mesh to prevent it from falling off. The test specimens were placed in a glass bottle, 40 g of ethyl acetate was poured in, and after shaking gently, they were left to stand at room temperature (23°C) for 72 hours. After standing, the test specimens were removed from the glass bottle and left at room temperature for 12 hours, and then dried in a vacuum oven at 100°C for 4 hours. After drying, the test specimens were cooled to room temperature and their mass M3 was measured, and the gel fraction was calculated using the following formula. Gel fraction (mass%)=[(M3-M2) / M1]×100 M1: Initial sample mass (mg) M2: Stainless steel mesh mass (mg) M3: Mass (mg) of the test specimen after sol extraction (gel portion of adhesive + stainless steel mesh)

[0157] (sol component) After removing the gel fraction test specimen from the glass vial, the ethyl acetate solution containing the extracted sol component was dried to prepare the measurement sample. The solid in the glass vial was diluted with tetrahydrofuran to adjust the sample concentration to 0.5 mg / mL. Gel permeation chromatography (GPC) was performed using this sample in the same manner as the measurement of weight-average molecular weight (Mw) described above. From the measured molecular weight distribution curve, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined, and the molecular weight distribution (Mw / Mn) was calculated from these measurements. Furthermore, we calculated the ratio of the peak area for molecular weights between 10,000 and 100,000 to the peak area for molecular weights between 10,000 and 30,000,000; the ratio of the peak area for molecular weights between 100,000 and 560,000 to the peak area for molecular weights between 10,000 and 30,000,000; and the ratio of the peak area for molecular weights of 560,000 or more to the peak area for molecular weights between 10,000 and 30,000,000.

[0158] (Adhesive strength) One release liner of the adhesive sheet was peeled off from the adhesive layer, and the corona-treated side of a polyethylene terephthalate (PET) film (Toyobo Ester® Film E5100: manufactured by Toyobo, 50 μm thick) was bonded to the adhesive layer surface. The sheet was then cut to a size of 25 mm wide and 100 mm long to create an adhesive sheet with a substrate. All sample preparation work was performed under conditions of 23°C and 50% RH. For this adhesive sheet with a substrate, the adhesive strength to a SUS304 steel plate was measured using the method specified in JIS Z 0237 (2009), but with the time from bonding to measurement changed to 24 hours, and the temperature of the adhesive sheet at the time of peeling set to 100°C. Specifically, the release sheet was peeled from the adhesive layer and pressed onto a SUS304 steel plate (surface finish BA (cold-rolled, bright heat treatment), surface roughness (Ra: 50±25nm as specified in JIS B 0601, thickness 1.0~1.2mm) by rolling a 2kg roller back and forth twice. The plate was then left to stand for 24 hours at 23°C and 50%RH. Next, the adhesive strength of the adhesive sheet was measured using a precision universal testing machine (Shimadzu Corporation, "AUTOGRAPH® AGS-1kNX, 50N load cell") under conditions of a peeling speed of 300mm / min and a peeling angle of 180°. When measuring the adhesive strength, a Peltier plate (AB-THERMO) was used to set the surface temperature of the adhesive sheet to 100°C.

[0159] (Vibration endurance test) The adhesive layers (adhesives) constituting the adhesive sheet were laminated using a hand roller to create a 1 mm thick laminate, which was used as the test specimen. Measurements were performed using a dynamic viscoelasticity analyzer (Anton Paar, MCR302), with the sample sandwiched between 8 mm diameter parallel plates. The measurement conditions were a temperature of 100°C, a stress of 25 kPa, a frequency of 10 Hz, and a vertical load of 5 N, with 50,000 vibrations. From the measurement results, the average value of the storage modulus (G') for 9,950 to 10,050 cycles (G1) and the average value of the storage modulus (G') for 49,900 to 50,000 cycles (G2) were calculated, and the rate of change of G2 relative to G1 was determined.

[0160] <(Meth)acrylic polymer manufacturing> (Synthesis Example 1: Polymer No. 1) In a flask equipped with a nitrogen gas inlet tube and a stirrer, the vinyl monomer, azo polymerization initiator, and solvent listed in Table 1 were charged. After purging with nitrogen, an organotellurium compound was added, and the reaction was carried out under the conditions listed in Table 1 to perform polymerization. After the reaction was complete, ethyl acetate was added to the reaction solution to obtain a solution containing polymer No. 1.

[0161] (Synthesis Examples 2, 3, 5-9: Polymers No. 2, 3, 5-9) Polymers No. 2, 3, and 5-9 were prepared using the same method as for polymer No. 1. Tables 1 and 2 show the vinyl monomer, organotellurium compound, azo polymerization initiator, solvent, reaction temperature, reaction time, and polymerization rate used.

[0162] (Synthesis Example 4: Polymer No. 4) EHA (475.0g), AA (25.0g), and AcOEt (409.3g) were charged into a flask equipped with a nitrogen gas inlet tube and a stirrer. After purging with nitrogen, the temperature was raised to 82°C, and AIBN (443.4mg) dissolved in AcOEt (50g) was added dropwise over 2 hours. The reaction was then allowed to proceed for a further 4 hours to polymerize. After the reaction was complete, ethyl acetate was added to the reaction solution to obtain a solution containing polymer No. 4.

[0163] Tables 1 and 2 show the polymerization conditions for each polymer. The amount of carboxyl groups and the glass transition temperature were calculated from the charge ratio and polymerization rate of the monomers used in the polymerization reaction.

[0164] [Table 1]

[0165] [Table 2]

[0166] <Manufacturing of adhesive compositions> (Adhesive composition No. 1) To a solution of polymer No. 1 obtained in Synthesis Example 1 (100 parts by mass of polymer component) and a solution of polymer No. 5 obtained in Synthesis Example 5 (300 parts by mass of polymer component), 0.027 parts by mass of a crosslinking agent (TETRAD®-C: manufactured by Mitsubishi Gas Chemical Company, 1,3-bis(N,N-diglycidylaminoethyl)cyclohexane, epoxy group amount: 9.8 mmol / g) was added and stirred to obtain adhesive composition No. 1. In adhesive composition No. 1, the reactive group (R1) of polymer No. 1 is a carboxyl group.

[0167] (Adhesive compositions No. 2-11) Adhesive compositions No. 2 to 11 were prepared in the same manner as adhesive composition No. 1, except that the formulation was changed as shown in Table 3. In adhesive compositions No. 2 to 11, the reactive group (R1) of the (meth)acrylic polymer (P1) is a carboxyl group.

[0168] [Table 3]

[0169] (Preparation of adhesive material) (Adhesive No. 1) The adhesive composition described in Table 4 was applied to the release surface of the first release sheet (PET film with a release treatment applied to its surface, Clean Sepa® HY-US20: manufactured by Higashiyama Film, thickness 75 μm) using a Baker-type applicator so that the film thickness after drying would be 50 μm. Then, it was dried in a constant temperature dryer at 60°C for 3 minutes, followed by drying at 150°C for 3 minutes. Next, the release surface of the second release sheet (PET film with a release treatment applied to its surface, Clean Sepa® HY-S10: manufactured by Higashiyama Film, thickness 38 μm) was bonded to the adhesive layer formed on the first release sheet, and then aged at 60°C for 3 days to create an adhesive layer sandwiched between the two release sheets.

[0170] (Adhesive No. 2-11) Adhesives No. 2 to 11 were manufactured in the same manner as adhesive No. 1, except that the adhesive composition was changed to adhesive compositions No. 2 to 11. The evaluation results of the adhesives formed from each adhesive composition are shown in Table 4.

[0171] [Table 4]

[0172] Adhesives No. 1 to 7 contain an adhesive composition that includes a (meth)acrylic polymer (P1) as a polymer component, which has structural units containing carboxyl groups and has a weight-average molecular weight of 300,000 to 3,000,000, and an epoxy crosslinking agent as a crosslinking agent, and the gel fraction of the adhesive is 3% to 95% by mass, and in the differential molecular weight distribution curve of the adhesive sol component, the ratio of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight of 10,000 to 30,000,000 is more than 40%. These adhesives No. 1-7 exhibited excellent adhesive strength at both 23°C and 100°C, as well as superior resistance to vibration.

[0173] Adhesive No. 8 is defined as an adhesive composition in which the polymer component contains structural units having carboxyl groups, but with a weight-average molecular weight of less than 300,000. This adhesive No. 8 has excellent adhesive strength at 23°C, but poor adhesive strength at 100°C.

[0174] Adhesives No. 9 to 11 are those in which, in the differential molecular weight distribution curve of the sol component of the adhesive, the ratio of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight of 10,000 to 30,000,000 is 40% or less. These adhesives, No. 9 to 11, had poor resistance to vibration.

[0175] The present invention includes the following embodiments.

[0176] (Aspect 1) In an adhesive material comprising a cured product of an adhesive composition containing a polymer component and a crosslinking agent, The polymer component includes a (meth)acrylic polymer (P1) having a structural unit having a reactive group (R1) for forming a crosslinked structure with the crosslinking agent, and having a weight-average molecular weight of 300,000 to 3,000,000. The aforementioned crosslinking agent is an epoxy-based crosslinking agent. The gel fraction of the adhesive is 3% by mass to 95% by mass. An adhesive characterized in that, in the differential molecular weight distribution curve of the sol component of the adhesive, the ratio of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight of 10,000 to 30,000,000 is greater than 40%.

[0177] (Aspect 2) The adhesive according to embodiment 1, wherein the weight-average molecular weight of the sol component of the adhesive is 1 million to 3 million.

[0178] (Aspect 3) The adhesive according to embodiment 1 or 2, wherein the molecular weight distribution (Mw / Mn) of the polymer (P1) is 5.0 or less.

[0179] (Aspect 4) The adhesive according to any one of embodiments 1 to 3, wherein the amount of reactive group (R1) in the polymer (P1) is 0.05 mmol / g to 1.5 mmol / g.

[0180] (Aspect 5) The adhesive according to any one of embodiments 1 to 4, wherein the reactive group (R1) is an acidic group.

[0181] (Aspect 6) The adhesive according to any one of embodiments 1 to 5, wherein the molar ratio ((R1) / epoxy group) of the reactive group (R1) of the polymer (P1) to the epoxy group of the crosslinking agent is 1 to 1000.

[0182] (Aspect 7) The adhesive according to any one of embodiments 1 to 6, wherein the crosslinking agent is at least one selected from the group consisting of aliphatic epoxy compounds, alicyclic epoxy compounds, aromatic epoxy compounds, and heterocyclic epoxy compounds.

[0183] (Pattern 8) The adhesive composition further contains a (meth)acrylic polymer (P2) as a polymer component, The polymer (P2) substantially does not contain structural units having a reactive group (R1), The adhesive according to any one of embodiments 1 to 7, wherein the weight-average molecular weight of the polymer (P2) is 600,000 to 3,000,000.

[0184] (Aspect 9) The adhesive according to embodiment 8, wherein the molecular weight distribution (Mw / Mn) of the polymer (P2) is 5.0 or less.

[0185] (Aspect 10) The adhesive according to embodiment 8 or 9, wherein the polymer (P2) contains structural units having heterocyclic groups and / or structural units having amide groups.

[0186] (Aspect 11) The adhesive according to any one of embodiments 8 to 10, wherein the total content of the structural units having heterocyclic groups and structural units having amide groups in the polymer (P2) is 0.1% to 10% by mass in 100% by mass of the polymer (P2).

[0187] (Aspect 12) The adhesive according to any one of embodiments 8 to 11, wherein the mass ratio of polymer (P2) to polymer (P1) in the adhesive composition (polymer (P2) / polymer (P1)) is 0.5 to 5.

[0188] (Aspect 13) An adhesive according to any one of embodiments 1 to 12, which is for use in optical components or automotive components.

[0189] (Aspect 14) It comprises a base film and an adhesive layer formed on at least one surface of the base film, An adhesive film characterized in that the adhesive layer is an adhesive material according to any one of embodiments 1 to 13.

[0190] (Aspect 15) An adhesive film comprising two release films and an adhesive layer sandwiched between the release films so as to be in contact with the release surfaces of the two release films, An adhesive film characterized in that the adhesive layer is an adhesive material according to any one of embodiments 1 to 13. [Industrial applicability]

[0191] Because the adhesive material of the present invention exhibits excellent adhesive strength and vibration resistance in high-temperature environments, it can be suitably used as an adhesive material for automotive components that are exposed to vibrations during operation in high-temperature environments, such as electronic equipment, automotive interior materials, and exterior materials used inside automobiles.

Claims

1. In an adhesive material comprising a cured product of an adhesive composition containing a polymer component and a crosslinking agent, The polymer component contains a (meth)acrylic polymer (P1) having a structural unit having a reactive group (R1) for forming a crosslinked structure with the crosslinking agent, and having a weight-average molecular weight of 300,000 to 3,000,000. The aforementioned crosslinking agent is an epoxy-based crosslinking agent. The gel fraction of the adhesive is 3% by mass to 95% by mass. An adhesive characterized in that, in the differential molecular weight distribution curve of the sol component of the adhesive, the ratio of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight of 10,000 to 30,000,000 is more than 40%.

2. The adhesive according to claim 1, wherein the weight-average molecular weight of the sol component of the adhesive is 1 million to 3 million.

3. The adhesive according to claim 1 or 2, wherein the molecular weight distribution (Mw / Mn) of the polymer (P1) is 5.0 or less.

4. The adhesive according to claim 1 or 2, wherein the amount of reactive group (R1) in the polymer (P1) is 0.05 mmol / g to 1.5 mmol / g.

5. The adhesive according to claim 1 or 2, wherein the reactive group (R1) is an acidic group.

6. The adhesive according to claim 1 or 2, wherein the molar ratio ((R1) / epoxy group) of the reactive group (R1) of the polymer (P1) to the epoxy group of the crosslinking agent is 1 to 1000.

7. The adhesive according to claim 1 or 2, wherein the crosslinking agent is at least one selected from the group consisting of aliphatic epoxy compounds, alicyclic epoxy compounds, aromatic epoxy compounds, and heterocyclic epoxy compounds.

8. The adhesive composition further contains a (meth)acrylic polymer (P2) as a polymer component, The polymer (P2) substantially does not contain structural units having a reactive group (R1), The adhesive according to claim 1, wherein the weight-average molecular weight of the polymer (P2) is 600,000 to 3,000,000.

9. The adhesive according to claim 8, wherein the molecular weight distribution (Mw / Mn) of the polymer (P2) is 5.0 or less.

10. The adhesive according to claim 8 or 9, wherein the polymer (P2) contains structural units having heterocyclic groups and / or structural units having amide groups.

11. The adhesive according to claim 10, wherein the total content of the structural units having heterocyclic groups and structural units having amide groups in the polymer (P2) is 0.1% by mass to 10% by mass in 100% by mass of the polymer (P2).

12. The adhesive according to claim 8 or 9, wherein the mass ratio of polymer (P2) to polymer (P1) in the adhesive composition (polymer (P2) / polymer (P1)) is 0.5 to 5.

13. The adhesive according to claim 1 or 8, which is for use in optical components or automotive components.

14. It comprises a base film and an adhesive layer formed on at least one surface of the base film, An adhesive film characterized in that the adhesive layer is the adhesive material described in claim 1 or 8.

15. An adhesive film comprising two release films and an adhesive layer sandwiched between the release films so as to be in contact with the release surfaces of the two release films, An adhesive film characterized in that the adhesive layer is the adhesive material described in claim 1 or 8.

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