Graft copolymer and curable composition

Abstract

Provided is a graft copolymer in which a (meth)acrylic acid ester-based polymer block (A) that has a reactive silicon group and a hydrocarbon-based polymer block (B) are bonded in the order of A-B-A. The content of (meth)acrylic acid alkyl esters in which an alkyl has 4 or more carbon atoms is preferably not less than 10 wt% in the graft copolymer. The (meth)acrylic acid ester-based polymer block (A) includes a structural unit derived from a chain transfer agent (a2) having a mercapto group, and the molar ratio of the hydrocarbon-based polymer block (B) to the chain transfer agent (a2) having a mercapto group is preferably not less than 0.06.

Description

Graft copolymer and curable composition

[0001] The present invention relates to a graft copolymer having reactive silicon groups and to a curable composition containing said polymer.

[0002] Organic polymers containing silicon groups that have hydroxyl groups or hydrolyzable groups on silicon atoms and that can form siloxane bonds through hydrolysis and condensation reactions (hereinafter also referred to as "reactive silicon groups") react with moisture, etc., even at room temperature. It is known that such organic polymers can be crosslinked by the siloxane condensation reaction of the reactive silicon groups to produce rubber-like cured products.

[0003] Known main chain skeletons of such reactive silyl group-containing organic polymers include polyoxyalkylene polymers, hydrocarbon polymers, (meth)acrylic acid ester polymers, etc. Furthermore, graft copolymers formed by bonding different polymer chains and having reactive silyl groups are also known.

[0004] As such graft copolymers, Patent Documents 1 and 2 describe reactive silicon group-containing graft copolymers produced by radical polymerization of an oligomer having double bonds at both ends, a vinyl monomer such as a (meth)acrylic acid ester, and a reactive silyl group-containing chain transfer agent. Various polymers such as polyether, polyester, polydienes, hydrogenated polydienes, polyisobutylene, and polydimethylsiloxane are exemplified as polymers constituting the oligomer, but in reality, only graft copolymers obtained using polyether-based oligomers have been produced.

[0005] International Publication No. 2007 / 023669 Japanese Patent Application Laid-Open No. 2005-15512

[0006] It is desirable that organic polymers having reactive silicon groups form cured products with high strength upon curing. However, cured products formed from (meth)acrylic acid ester polymers having reactive silicon generally tend to be brittle and have low strength. In addition, cured products obtained from (meth)acrylic acid ester polymers having reactive silicon tend to have high water vapor permeability. When applied to areas requiring low moisture permeability, it is necessary to reduce the moisture permeability of the cured product. Furthermore, from the viewpoint of workability when applying the curable composition, it is desirable that the curable composition exhibits a low viscosity during application, but a high viscosity after application, making it less likely to drip, i.e., so-called thixotropy.

[0007] In view of the above-mentioned current situation, an object of the present invention is to provide a reactive silicon group-containing polymer that exhibits thixotropy and achieves improved strength and reduced moisture permeability after curing.

[0008] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by constructing a (meth)acrylic acid ester-based polymer having a reactive silicon group as a graft copolymer containing a hydrocarbon-based polymer block, bonding the blocks in a specific order, and setting the content of the (meth)acrylic acid alkyl ester having an alkyl group having 4 or more carbon atoms and / or the molar ratio of the hydrocarbon-based polymer block to the chain transfer agent having a mercapto group within a specific range, thereby completing the present invention.

[0009] That is, the first aspect of the present invention is a compound represented by the general formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. X represents a hydroxyl group or a hydrolyzable group. a represents 2 or 3. The present invention relates to a graft copolymer in which a (meth)acrylic acid ester-based polymer block (A) having a reactive silicon group represented by the following formula (1): and a hydrocarbon-based polymer block (B) are bonded in the order A-B-A, wherein the content of the (meth)acrylic acid alkyl ester having an alkyl carbon number of 4 or more is 10% by weight or more in the graft copolymer. That is, a second aspect of the present invention relates to a graft copolymer in which a (meth)acrylic acid alkyl ester having an alkyl carbon number of 4 or more is bonded in the order A-B-A. １ ３－ａ X ａ (1) (wherein, R １ represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. X represents a hydroxyl group or a hydrolyzable group. a represents 2 or 3. The present invention relates to a graft copolymer in which a (meth)acrylic acid ester-based polymer block (A) having a reactive silicon group represented by the following formula (I) is bonded to a hydrocarbon-based polymer block (B) in the order A-B-A, wherein the (meth)acrylic acid ester-based polymer block (A) contains a structural unit derived from a chain transfer agent (a2) having a mercapto group, and the molar ratio of the hydrocarbon-based polymer block (B) to the chain transfer agent (a2) having a mercapto group is 0.06 or more. The present invention also relates to a curable composition or a hot-melt adhesive comprising the graft copolymer according to the first or second aspect.

[0010] According to the present invention, it is possible to provide a reactive silicon group-containing polymer that exhibits thixotropy and achieves improved strength and reduced moisture permeability after curing. The graft copolymer according to a preferred embodiment of the present invention is solid at room temperature and can be used as a main resin component in hot melt adhesives.

[0011] Conceptual diagram of an H-type structure that may be contained in the graft copolymer according to the present disclosure.

[0012] The following describes specific embodiments of the present invention, but the present invention is not limited to these embodiments.

[0013] The graft copolymer according to this embodiment is formed by bonding a (meth)acrylic acid ester polymer block (A) and a hydrocarbon polymer block (B). The graft copolymer has a reactive silicon group, and the reactive silicon group is bonded to the (meth)acrylic acid ester polymer block (A). In this application, "(meth)acrylic" refers to "acrylic and / or methacrylic."

[0014] <Reactive Silicon Group> The (meth)acrylic acid ester polymer block (A) has a reactive silicon group represented by the following general formula (1) at the molecular chain terminal and / or side chain (non-terminal site): —SiR １ ３－ａ X ａ (1) (wherein, R １ represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms; X represents a hydroxyl group or a hydrolyzable group; and a represents 2 or 3.

[0015] R １ The hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and even more preferably 1 to 3 carbon atoms. １ Specific examples of the methyl group include a methyl group, an ethyl group, a chloromethyl group, a methoxymethyl group, and an N,N-diethylaminomethyl group. Preferred are a methyl group, an ethyl group, a chloromethyl group, and a methoxymethyl group, and more preferred are a methyl group and a methoxymethyl group.

[0016] Examples of X include a hydroxyl group, a halogen, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, a mercapto group, an alkenyloxy group, etc. Among these, an alkoxy group is more preferred because it is mildly hydrolyzable and easy to handle, and a methoxy group and an ethoxy group are particularly preferred.

[0017] Specific examples of the reactive silicon group include, but are not limited to, a trimethoxysilyl group, a triethoxysilyl group, a tris(2-propenyloxy)silyl group, a triacetoxysilyl group, a dimethoxymethylsilyl group, a diethoxymethylsilyl group, a dimethoxyethylsilyl group, a (chloromethyl)dimethoxysilyl group, a (chloromethyl)diethoxysilyl group, a (methoxymethyl)dimethoxysilyl group, a (methoxymethyl)diethoxysilyl group, an (N,N-diethylaminomethyl)dimethoxysilyl group, and an (N,N-diethylaminomethyl)diethoxysilyl group. Among these, methyldimethoxysilyl group, trimethoxysilyl group, triethoxysilyl group, (chloromethyl)dimethoxysilyl group, (methoxymethyl)dimethoxysilyl group, (methoxymethyl)diethoxysilyl group, and (N,N-diethylaminomethyl)dimethoxysilyl group are preferred because they exhibit high activity and give cured products with good mechanical properties, and trimethoxysilyl group and triethoxysilyl group are more preferred, with trimethoxysilyl group being even more preferred, because they give cured products with high breaking strength.

[0018] From the viewpoint of achieving the above-described effects of the present invention, the reactive silicon group equivalent of the graft copolymer according to this embodiment is preferably 0.1 to 0.55 mmol / g, more preferably 0.2 mmol / g or more, and even more preferably 0.3 mmol / g or more. The reactive silicon group equivalent is preferably 0.45 mmol / g or less.

[0019] <(Meth)acrylic acid ester-based polymer block (A)> The (meth)acrylic acid ester-based polymer block (A) is a polymer block containing at least a structural unit derived from a (meth)acrylic acid ester (a1). Preferably, the (meth)acrylic acid ester-based polymer block (A) is a polymer block containing, in addition to the structural unit derived from the (meth)acrylic acid ester (a1), a structural unit derived from a chain transfer agent (a2) having a mercapto group.

[0020] <(Meth)acrylic acid ester (a1)> The (meth)acrylic acid ester (a1) is roughly classified into (meth)acrylic acid ester (a1-1) having no reactive silicon group and (meth)acrylic acid ester (a1-2) having a reactive silicon group.The (meth)acrylic acid ester (a1-1) not having a reactive silicon group is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, and methyl (meth)acrylate. n-Octyl acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, (meth) Examples of suitable acrylates include 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth)acrylate, ethylene oxide adducts of (meth)acrylic acid, 2,2,2-trifluoroethyl (meth)acrylate, 3,3,3-trifluoropropyl (meth)acrylate, 3,3,4,4,4-pentafluorobutyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, trifluoromethyl (meth)acrylate, perfluoroethyl (meth)acrylate, bis(trifluoromethyl)methyl (meth)acrylate, 2-trifluoromethyl-2-perfluoroethylethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, chloroethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, and 2-aminoethyl (meth)acrylate. One type may be used alone, or two or more types may be used in combination. As the (meth)acrylic acid ester (a1-1) having no reactive silicon group, a (meth)acrylic acid alkyl ester is preferred.

[0021] From the viewpoints of improving the strength of the cured product, reducing moisture permeability, and improving thixotropy, the content of the (meth)acrylic acid ester (a1-1) having no reactive silicon group in the graft copolymer is preferably 25% by weight or more, more preferably 30% by weight or more, even more preferably 40% by weight or more, and particularly preferably 50% by weight or more. The upper limit is preferably 80% by weight or less, more preferably 70% by weight or less, and even more preferably 65% ​​by weight or less.

[0022] The (meth)acrylic acid ester (a1-1) having no reactive silicon group preferably contains a (meth)acrylic acid alkyl ester having an alkyl carbon number of 4 or more. This improves the compatibility between the (meth)acrylic acid ester (a1) and the polyfunctional macromonomer (a4) described below during the production of the graft copolymer, thereby enabling the production of a graft copolymer exhibiting good physical properties. The upper limit of the number of carbon atoms is not particularly limited, but may be, for example, 30 or less, 20 or less, 15 or less, or 12 or less.

[0023] Specific examples of the (meth)acrylic acid alkyl ester in which the alkyl has 4 or more carbon atoms include n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.

[0024] The content of the (meth)acrylic acid alkyl ester having an alkyl carbon number of 4 or more is preferably 10% by weight or more, more preferably 20% by weight or more, even more preferably 30% by weight or more, and particularly preferably 40% by weight or more, in the graft copolymer, from the viewpoints of improving the strength of the cured product, reducing moisture permeability, and improving thixotropy, and also from the viewpoint of facilitating the production of the graft copolymer. The upper limit is preferably 75% by weight or less, more preferably 65% ​​by weight or less, and even more preferably 60% by weight or less.

[0025] The (meth)acrylic acid ester (a1-2) having a reactive silicon group is an optional monomer and does not necessarily have to be used, but its use is preferred. The reactive silicon group contained in (a1-2) is the reactive silicon group represented by the above-mentioned general formula (1). By using the monomer (a1-2), the reactive silicon group can be introduced into the side chain (non-terminal portion) of the (meth)acrylic acid ester polymer block (A).

[0026] The (meth)acrylic acid ester (a1-2) having a reactive silicon group is not particularly limited, and examples thereof include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyldimethoxymethylsilane, (meth)acryloxymethyltrimethoxysilane, (meth)acryloxymethyldimethoxymethylsilane, etc. These compounds may be used alone or in combination of two or more.

[0027] When a (meth)acrylic acid ester (a1-2) having a reactive silicon group is used, the content of (a1-2) is preferably from 0 to 30% by weight, more preferably from 0 to 10% by weight, even more preferably from 0.1 to 7% by weight, and particularly preferably from 0.2 to 6% by weight, of the total amount of structural units forming the (meth)acrylic acid ester-based polymer block (A).

[0028] <Chain Transfer Agent (a2) Having a Mercapto Group> By using a chain transfer agent (a2) having a mercapto group, the molecular weight of the (meth)acrylic acid ester-based polymer block (A) can be controlled. Furthermore, the molecular weight distribution of the graft copolymer can be made relatively narrow, and gelation during synthesis of the graft copolymer can be suppressed. Furthermore, it becomes possible to preferentially synthesize polymer molecules in which one hydrocarbon-based polymer block (B) is introduced into one molecule of the graft copolymer.

[0029] The chain transfer agent (a2) having a mercapto group may not have a reactive silicon group, but preferably has a reactive silicon group. The reactive silicon group is the reactive silicon group represented by the above-mentioned general formula (1). When the chain transfer agent (a2) having a mercapto group further has a reactive silicon group, the reactive silicon group can be introduced into the molecular chain terminal of the (meth)acrylic acid ester polymer block (A).

[0030] The chain transfer agent (a2) having a mercapto group is not particularly limited, and examples thereof include 3-mercaptopropyldimethoxymethylsilane, 3-mercaptopropyltrimethoxysilane, (mercaptomethyl)dimethoxymethylsilane, (mercaptomethyl)trimethoxysilane, n-dodecyl mercaptan, tert-dodecyl mercaptan, and lauryl mercaptan.

[0031] The content of the chain transfer agent (a2) having a mercapto group is preferably from 1 to 10% by weight, more preferably from 2 to 8% by weight, and even more preferably from 3 to 6% by weight, of the total amount of structural units forming the (meth)acrylic acid ester polymer block (A).

[0032] Furthermore, the content of the chain transfer agent (a2) having a mercapto group preferably accounts for 0.1 mol % or more and 10 mol % or less, more preferably 0.4 mol % or more and 9 mol % or less, even more preferably 0.5 mol % or more and 7 mol % or less, and particularly preferably 0.6 mol % or more and 6 mol % or less, of the total amount of structural units forming the (meth)acrylic acid ester-based polymer block (A).

[0033] The ratio of the content of the hydrocarbon polymer block (B) to the content of the chain transfer agent (a2) having a mercapto group is preferably 0.06 or more, more preferably 0.08 or more, and even more preferably 0.10 or more, as the molar ratio of hydrocarbon polymer block (B) / chain transfer agent (a2), particularly from the viewpoint of improving the strength of the cured product. The larger this value, the higher the proportion of polymer molecules containing the hydrocarbon polymer block (B) in the graft copolymer, and the greater the strength of the cured product can be. The upper limit of this molar ratio is not particularly limited, but from the viewpoints of improving the strength of the cured product, reducing moisture permeability, and improving thixotropy, it is preferably 0.60 or less, more preferably 0.40 or less, even more preferably 0.30 or less, and particularly preferably 0.20 or less.

[0034] The graft copolymer or (meth)acrylic acid ester polymer block (A) according to this embodiment has a substituent (—S—R 2 described later) derived from the chain transfer agent (a2) having a mercapto group. ８ Since the compound has a structure represented by the formula (I), it may contain a sulfur atom.

[0035] The sulfur atom concentration of the graft copolymer according to this embodiment is preferably 2,000 ppm or more and 15,000 ppm or less. The sulfur atom concentration is a value relative to the solid content of the graft copolymer, and the solvent is excluded from the calculation.

[0036] The sulfur atom concentration is a value that reflects the proportion of chain transfer agent used in the graft polymer. The lower the sulfur atom concentration, the lower the proportion of chain transfer agent used, and therefore the block (A) tends to have a relatively high molecular weight. As a result, the viscosity of the graft copolymer when heated and melted tends to be high. Conversely, the higher the sulfur atom concentration, the higher the proportion of chain transfer agent used, and therefore the block (A) tends to have a relatively low molecular weight. As a result, the strength of the cured product may be reduced.

[0037] The lower limit of the sulfur atom concentration is preferably 3,500 ppm or more, more preferably 5,000 ppm or more, and the upper limit is preferably 12,000 ppm or less, more preferably 10,000 ppm or less, and particularly preferably 8,000 ppm or less.

[0038] The method for measuring the sulfur atom concentration is not particularly limited. It can be measured by known elemental analysis methods such as organic elemental analysis and X-ray fluorescence analysis. The sulfur atom concentration may also be a theoretical value calculated from the total amount of the constituent components used in the production of the graft copolymer and the amount of the chain transfer agent (a2) having a mercapto group.

[0039] The (meth)acrylic acid ester-based polymer block (A) can have a reactive silicon group by satisfying either or both of the following two conditions: Condition 1: The (meth)acrylic acid ester (a1) contains a (meth)acrylic acid ester (a1-2) having a reactive silicon group; and Condition 2: The chain transfer agent (a2) having a mercapto group further has a reactive silicon group.

[0040] In order to obtain a cured product having high strength, it is preferable to introduce reactive silicon groups under both condition 1 and condition 2. Specifically, from the viewpoint of the restorability of the cured product, the reactive silicon group equivalent derived from (a1) is preferably 0.01 mmol / g or more, more preferably 0.10 mmol / g or more. Furthermore, from the viewpoint of the elongation of the cured product, the reactive silicon group equivalent derived from (a1) is preferably 0.40 mmol / g or less, more preferably 0.30 mmol / g or less, and even more preferably 0.20 mmol / g or less. Meanwhile, the reactive silicon group equivalent derived from (a2) is preferably 0.05 mmol / g or more, more preferably 0.10 mmol / g or more. Furthermore, the reactive silicon group equivalent derived from (a2) is preferably 0.40 mmol / g or less, more preferably 0.30 mmol / g or less, and even more preferably 0.20 mmol / g or less.

[0041] The constituent components forming the (meth)acrylic acid ester-based polymer block (A) may or may not contain another monomer (a3) ​​that does not fall under either (a1) or (a2) described in detail above.

[0042] Examples of the other monomer (a3) ​​include styrene-based monomers such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, and styrenesulfonic acid; fluorine-containing vinyl monomers such as perfluoroethylene, perfluoropropylene, and vinylidene fluoride; maleic acid and derivatives thereof such as maleic acid, maleic anhydride, maleic acid monoalkyl esters, and maleic acid dialkyl esters; fumaric acid and derivatives thereof such as fumaric acid, fumaric acid monoalkyl esters, and fumaric acid dialkyl esters; maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, and butylmaleimide. maleimide-based monomers such as hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, and cyclohexylmaleimide; vinyl ester-based monomers such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate; olefin-based monomers such as ethylene and propylene; conjugated diene-based monomers such as butadiene and isoprene; (meth)acrylamide; (meth)acrylonitrile; and vinyl-based monomers such as vinyl chloride, vinylidene chloride, allyl chloride, allyl alcohol, ethyl vinyl ether, and butyl vinyl ether. Only one type of other monomer may be used, or two or more types may be used in combination.

[0043] <Hydrocarbon-Based Polymer Block (B)> The polymer block (B) is composed of a hydrocarbon-based polymer. By constructing a graft copolymer by introducing the hydrocarbon-based polymer block (B) between the (meth)acrylic acid ester-based polymer blocks (A), the graft copolymer exhibits thixotropy, and after curing, it is possible to achieve improved strength and reduced moisture permeability.

[0044] The hydrocarbon polymer refers to a polymer having a polymer skeleton formed by polymerizing an unsaturated hydrocarbon compound such as an olefin or a diene. Specific examples include polyisobutylene polymers and diene polymers. From the viewpoints of improving the strength of the cured product, reducing moisture permeability, and improving thixotropy, polyisobutylene polymers are preferred.

[0045] The polyisobutylene polymer is a polymer containing isobutene as a constituent monomer as a main component. It may be a polymer containing only isobutene as a constituent monomer, or it may be a copolymer containing a comonomer other than isobutene. Examples of such comonomers include aliphatic olefins (e.g., 1-butene); aromatic vinyl compounds (e.g., styrene, methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene); dienes (e.g., 1,3-butadiene, isoprene); vinyl ethers (e.g., butyl vinyl ether); silanes (e.g., vinyltrimethylsilane, allyltrimethylsilane); terpenes (e.g., α-pinene, β-pinene, limonene); vinylcarbazole; and acenaphthylene. The comonomer used is preferably at least one selected from the group consisting of 1-butene, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, 1,3-butadiene, isoprene, α-pinene, β-pinene, and limonene, because it is easily copolymerizable with isobutene and the physical properties of the resulting copolymer are favorable.

[0046] The content of the comonomer contained in the polyisobutylene polymer is preferably less than 50% by weight, more preferably 30% by weight or less, and even more preferably 10% by weight or less, of the total of isobutene and the comonomer.

[0047] The diene polymer refers to a polymer containing a diene as a main constituent monomer. Examples of the diene include 1,3-butadiene, 1,3-pentadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 2-propyl-1,3-butadiene, 1,3-heptadiene, 6-methyl-1,3-heptadiene, 1,3-hexadiene, 5-methyl-1,3-hexadiene, 2,4-hexadiene, 2,5-dimethyl-2,4-hexadiene, and 1,3-octadiene. Only one diene may be used, or two or more dienes may be used in combination. Among these, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is particularly preferred.

[0048] The diene polymer may be a polymer containing only a diene as a constituent monomer, or a copolymer containing a comonomer other than a diene. As such a comonomer, those mentioned above as comonomers usable for polyisobutylene polymers can be used. Among them, aromatic vinyl compounds are preferred, and styrene is particularly preferred.

[0049] The content of the comonomer contained in the diene polymer is preferably less than 50% by weight, more preferably 30% by weight or less, and even more preferably 10% by weight or less, of the total of the diene and the comonomer.

[0050] The diene polymer may be either non-hydrogenated or hydrogenated, but is preferably hydrogenated from the viewpoint of obtaining good heat resistance and weather resistance.

[0051] Preferred examples of the diene polymer include polybutadiene polymers, polyisoprene polymers, hydrogenated polybutadiene polymers, and hydrogenated polyisoprene polymers.

[0052] The polybutadiene-based polymer or hydrogenated polybutadiene-based polymer is a polymer containing 1,3-butadiene as a main constituent monomer. It may be a polymer containing only 1,3-butadiene as a constituent monomer, or it may be a copolymer containing a comonomer other than 1,3-butadiene. Examples of the comonomer other than 1,3-butadiene include comonomers other than the dienes mentioned above and dienes other than 1,3-butadiene.

[0053] The content of the comonomer contained in the polybutadiene-based polymer or hydrogenated polybutadiene-based polymer is preferably less than 50% by weight, more preferably 30% by weight or less, and even more preferably 10% by weight or less, of the total of 1,3-butadiene and the comonomer.

[0054] The polyisoprene polymer or hydrogenated polyisoprene polymer is a polymer containing isoprene as a constituent monomer as a main component. It may be a polymer containing only isoprene as a constituent monomer, or it may be a copolymer containing a comonomer other than isoprene. Examples of the comonomer other than isoprene include the comonomers other than the dienes mentioned above and dienes other than isoprene.

[0055] The content of the comonomer contained in the polyisoprene-based polymer or hydrogenated polyisoprene-based polymer is preferably less than 50% by weight, more preferably 30% by weight or less, and even more preferably 10% by weight or less, of the total of isoprene and comonomer.

[0056] The number average molecular weight of the hydrocarbon polymer block (B) is preferably 1,000 or more, more preferably 3,000 or more, even more preferably 5,000 or more, even more preferably 8,000 or more, and particularly preferably 10,000 or more, from the viewpoint of improving the strength, reducing moisture permeability, and improving thixotropy of the cured product. The upper limit is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 30,000 or less, from the viewpoint of reducing the viscosity during heat melting.

[0057] The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the hydrocarbon polymer block (B) is not particularly limited, but is preferably narrow, specifically, preferably less than 2.0, more preferably 1.6 or less, even more preferably 1.4 or less, even more preferably 1.3 or less, particularly preferably 1.2 or less, and most preferably 1.1 or less. The narrower the molecular weight distribution, the lower the viscosity when heated and melted tends to be.

[0058] The number average molecular weight (Mn) and weight average molecular weight (Mw) of the hydrocarbon polymer block (B) are values ​​measured in terms of polystyrene using the polyfunctional macromonomer (a4) described below by gel permeation chromatography (GPC). The detailed measurement method is described in the Examples.

[0059] The hydrocarbon polymer block (B) can be introduced into the graft copolymer by using a hydrocarbon polymer (a4) having, on average, more than one (meth)acryloyl group per molecule. The polymer (a4) is itself a polymer, but is one of the components constituting the graft copolymer according to this embodiment. Since the polymer (a4) has a (meth)acryloyl group, it can be copolymerized with the (meth)acrylic acid ester (a1). Moreover, since the polymer (a4) has more than one (meth)acryloyl group per molecule, it can function as a so-called polyfunctional macromonomer. Hereinafter, the polymer (a4) will also be referred to as a polyfunctional macromonomer (a4).

[0060] The polyfunctional macromonomer (a4) may have only acryloyl groups, only methacryloyl groups, or both acryloyl groups and methacryloyl groups as (meth)acryloyl groups.

[0061] The (meth)acryloyl group contained in the polyfunctional macromonomer (a4) is not particularly limited, but can be represented by the following general formula (2), (3), or (4): CH ２ = C(R ２ )-C(=O)-OR ３ -NH-C(=O)-OB (2) CH ２ = C(R ２ )-C(=O)-OB (3) CH ２ = C(R ２ )-C(=O)-OR ４ -O-R ５ -B (4) In each formula, R ２ represents hydrogen or a methyl group. B represents a hydrocarbon polymer block (B).

[0062] R in formula (2) ３ represents a divalent saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. The number of carbon atoms is preferably 1 to 10, more preferably 1 to 6, and particularly preferably 1 to 3.

[0063] R in formula (4) ４represents a divalent saturated hydrocarbon group having 1 to 6 carbon atoms. In particular, an alkylene group is preferred, and specific examples include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group. From the viewpoints of availability of raw materials and reactivity, a butylene group or a pentylene group is preferred.

[0064] R in formula (4) ５ represents a phenylene group. The phenylene group may or may not have a substituent on the benzene ring. Examples of the substituent include a monovalent hydrocarbon group having 1 to 20 carbon atoms and an alkoxy group. Specific examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a 2-ethylhexyl group, a nonyl group, and a decanyl group. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. A methyl group or a methoxy group is preferred.

[0065] The polyfunctional macromonomer (a4) has, on average, more than one (meth)acryloyl group per molecule. From the viewpoint of improving the strength of the cured product, the average number of (meth)acryloyl groups per molecule of the polyfunctional macromonomer (a4) is preferably 1.1 to 5, more preferably 1.3 to 4, even more preferably 1.6 to 2.5, and particularly preferably 1.8 to 2.0. The average number is, for example, １ It can be calculated from the H NMR spectrum.

[0066] The polyfunctional macromonomer (a4) may have a (meth)acryloyl group at either or both of the molecular chain terminal and the side chain of the hydrocarbon polymer. From the viewpoint of the strength of the cured product, it is preferable that the (meth)acryloyl group be present at the molecular chain terminal. In particular, it is particularly preferable that the polyfunctional macromonomer (a4) has a linear main chain skeleton and has a (meth)acryloyl group at each of both ends of the molecular chain.

[0067] The method for synthesizing the polyfunctional macromonomer (a4) is not particularly limited, but examples thereof include a method in which a hydrocarbon polymer having more than one hydroxyl group in the molecule (preferably a linear hydrocarbon polymer having hydroxyl groups at both ends) is prepared, and a (meth)acryloyl group is introduced using the hydroxyl group.

[0068] As an example of a method for synthesizing the polyfunctional macromonomer (a4), a compound having an isocyanate group and a (meth)acryloyl group can be reacted with a hydrocarbon polymer having a hydroxyl group to form a urethane bond and introduce the (meth)acryloyl group. Specific examples of the compound having an isocyanate group and a (meth)acryloyl group include isocyanate ethyl (meth)acrylate, isocyanate propyl (meth)acrylate, isocyanate butyl (meth)acrylate, and isocyanate hexyl (meth)acrylate.

[0069] As another example of a method for synthesizing the polyfunctional macromonomer (a4), a hydrocarbon polymer having a hydroxyl group can be reacted with a diisocyanate compound to introduce an isocyanate group into the polymer, and then a compound having a hydroxyl group and a (meth)acryloyl group can be reacted to introduce a (meth)acryloyl group. Specific examples of the diisocyanate compound include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and 4,4'-diphenylmethane diisocyanate. Specific examples of the compound having a hydroxyl group and a (meth)acryloyl group include hydroxybutyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate.

[0070] As another example of the synthesis method of the polyfunctional macromonomer (a4), an acid anhydride is reacted with a hydrocarbon polymer having a hydroxyl group to introduce a carboxyl group into the polymer, and then a compound having an epoxy group and a (meth)acryloyl group is reacted to introduce a (meth)acryloyl group.Specific examples of the acid anhydride include succinic anhydride, maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhimic anhydride, trimellitic anhydride, methylnadic anhydride, and dodecyl succinic anhydride.Specific examples of the compound having an epoxy group and a (meth)acryloyl group include glycidyl (meth)acrylate.

[0071] Another example of a method for synthesizing the polyfunctional macromonomer (a4) is a method in which a hydrocarbon polymer having a hydroxyl group is subjected to dehydration condensation with methacrylic acid or acrylic acid. To carry out the reaction under milder conditions, a hydrocarbon polymer having a hydroxyl group is reacted with methacrylic acid chloride, methacrylic acid bromide, methacrylic acid iodide, acrylic acid chloride, acrylic acid bromide, acrylic acid iodide, or the like.

[0072] Another example of a method for synthesizing the polyfunctional macromonomer (a4) is to subject isobutylene to living cationic polymerization in the presence of a bifunctional polymerization initiator, a Lewis acid catalyst, and an electron donor component to form a main chain of a polyisobutylene polymer, and then react the polymer with a compound having a benzene ring and a (meth)acryloyl group (e.g., a (meth)acrylate phenoxyalkyl compound, etc.) to introduce a (meth)acryloyl group into the terminal of the main chain. In this method, the number of (meth)acryloyl groups introduced into the main chain can be controlled by adjusting the amount of the compound added.

[0073] Examples of bifunctional polymerization initiators include p-dicumyl chloride and 1,4-bis(chloromethyl)benzene. Examples of Lewis acid catalysts include titanium tetrachloride. Examples of electron donor components include nitrogen-containing compounds (e.g., 2-methylpyridine, 2,6-lutidine, triethylamine, etc.).

[0074] Yet another example of a method for synthesizing the polyfunctional macromonomer (a4) is a method in which a monomer having both a cationically polymerizable functional group and a (meth)acryloyl group is prepared, and this monomer is randomly copolymerized with isobutylene to obtain a polyisobutylene-based polymer having a (meth)acryloyl group as a side chain.

[0075] Commercially available products can also be used as the polyfunctional macromonomer (a4). Examples of such commercially available products include EPION EP-400V (manufactured by Kaneka Corporation, polyisobutylene polymer), NISSO-PB TEAI-1000 (manufactured by Nippon Soda Co., Ltd., hydrogenated polybutadiene polymer), NISSO-PB TE-2000 (manufactured by Nippon Soda Co., Ltd., polybutadiene polymer), CN9014 (manufactured by Sartomer, hydrogenated polybutadiene polymer), UC-102M (manufactured by Kuraray Co., Ltd., polyisoprene polymer), UC-203M (manufactured by Kuraray Co., Ltd., polyisoprene polymer), and BAC-45 (manufactured by Osaka Organic Chemical Industry Ltd., polybutadiene polymer).

[0076] In the graft copolymer according to this embodiment, the proportion of block (A) relative to the total of the (meth)acrylic acid ester polymer block (A) and the hydrocarbon polymer block (B) is preferably 30 to 85% by weight, and the proportion of block (B) is preferably 15 to 70% by weight. Within these ranges, the balance between the physical properties achieved by block (A) and the physical properties achieved by block (B) is good, making it easy to achieve improved strength, reduced moisture permeability, and improved thixotropy of the cured product.

[0077] The proportion of block (A) is preferably 35% by weight or more and the proportion of block (B) is preferably 65% ​​by weight or less, more preferably 50% by weight or more and 50% by weight or less, and even more preferably 55% by weight or more and 45% by weight or less of block (B).

[0078] Furthermore, the proportion of block (A) is preferably 80% by weight or less and the proportion of block (B) is preferably 20% by weight or more, more preferably 75% by weight or less and the proportion of block (B) is 25% by weight or more, and even more preferably 70% by weight or less and the proportion of block (B) is 30% by weight or more.

[0079] From the viewpoint of the effects of the present invention described above, the content of the hydrocarbon polymer block (B) is preferably from 0.05 mol % to 6.0 mol %, more preferably from 0.1 mol % to 2.3 mol %, and even more preferably from 0.2 mol % to 1.5 mol %, of the total amount of structural units forming the graft copolymer.

[0080] The average number of hydrocarbon polymer blocks (B) per molecule of the graft copolymer according to this embodiment is preferably 0.05 or more and 2.0 or less, from the viewpoint of the strength of the resulting cured product. The lower limit is more preferably 0.07 or more, and even more preferably 0.08 or more. The upper limit is more preferably 1.5 or less, and even more preferably 1.0 or less. The average number can be calculated by the following formula: number average molecular weight of graft copolymer (g / mol) / (weight of graft copolymer (g) / (number of moles of polymer block (B))).

[0081] <Block Bonding Form> In the graft copolymer according to this embodiment, a (meth)acrylic acid ester polymer block (A) and a hydrocarbon polymer block (B) are bonded in the order A-B-A. However, the graft copolymer is not limited to a triblock copolymer, and may include a structure in which a block (B) and / or a block (A) is further bonded to the triblock copolymer.

[0082] The graft copolymer according to this embodiment may be produced by free radical polymerization. In this case, some molecules in the graft copolymer may contain polymer components in which the block (A) and the block (B) are not bonded to each other. In this application, the term "graft copolymer" is defined as including such non-bonded polymer components. The ratio of the graft copolymer in which the block (A) and the block (B) are bonded to each other and the non-bonded polymer components can be easily determined by known means, for example, GPC analysis.

[0083] In the graft copolymer according to this embodiment, the block (A) and the block (B) are preferably bonded via an ester bond derived from a (meth)acryloyl group in the polyfunctional macromonomer (a4) (i.e., the ester bond in the general formulae (2) to (4)).

[0084] The bonding form between the block (A) and the block (B) is not particularly limited, but can be represented by the following general formula (5), (6), or (7): A-C(=O)-O-R ３ -NH-C(=O)-O-B (5) A-C(=O)-O-B (6) A-C(=O)-O-R ４ -O-R ５ -B (7) In each formula, A represents the polymer block (A) and B represents the polymer block (B). ３ ~R ５ is the same as described above for equations (2) and (4).

[0085] When a high-strength, high-elongation cured product is desired, it is preferable that block (A) is composed of a hard polymer and block (B) is composed of a soft polymer. When a low-viscosity graft copolymer is desired, it is preferable that both block (A) and block (B) are composed of soft polymers. Here, a hard polymer refers to a polymer with a high glass transition temperature. A soft polymer refers to a polymer with a low glass transition temperature.

[0086] When the block (A) is composed of a hard polymer, the (meth)acrylic acid ester (a1-1) preferably contains an alkyl methacrylate ester having 4 or less alkyl carbon atoms, particularly methyl methacrylate. Alternatively, it may contain isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, or the like. When the block (A) is composed of a soft polymer, the (meth)acrylic acid ester (a1-1) preferably contains an alkyl (meth)acrylate ester having 4 or more alkyl carbon atoms.

[0087] When the block (A) is a molecular chain formed by reacting with a chain transfer agent (a2) having a mercapto group, the block (A) has at its terminal a substituent derived from (a2) such as -S-R ８ In the formula, S represents a sulfur atom, and R ８ represents a hydrocarbon group which may have a reactive silicon group. Examples of the hydrocarbon group include an alkyl group, an aryl group, or an aralkyl group having 1 to 20 carbon atoms. The reactive silicon group is the reactive silicon group represented by the general formula (1) described above. R ８ Specific examples of the group include a reactive silicon group-containing methyl group, a reactive silicon group-containing propyl group, an n-dodecyl group, a tert-dodecyl group, and a lauryl group.

[0088] The graft copolymer according to this embodiment may have a linear structure in which the end of block (A) and the end of block (B) are linked, but preferably includes an H-type structure. FIG. 1 shows a conceptual diagram of the H-type structure. In this structure, two vertical bars correspond to block (A) and one horizontal bar corresponds to block (B). Both ends of block (B) are bonded to non-terminal portions of block (A). One end of each of the two blocks (A) contains a substituent, -S-R, derived from a chain transfer agent having a mercapto group and a reactive silicon group. ８ -SiR １ ３－ａ X ａ In addition, the non-terminal portion of the block (A) also has -SiR １ ３－ａ Xａ are randomly bonded, which are derived from the (meth)acrylic acid ester (a1-2) having a reactive silicon group.

[0089] The H-type structure can be formed by randomly polymerizing a polyfunctional macromonomer (a4) having a (meth)acryloyl group at each end of the hydrocarbon polymer molecular chain, a (meth)acrylic acid ester (a1), and a chain transfer agent (a2) having a mercapto group.

[0090] <Molecular Weight of Graft Copolymer> The number average molecular weight of the graft copolymer according to this embodiment is not particularly limited, but is preferably 500 to 50,000, more preferably 500 to 30,000, and particularly preferably 1,000 to 10,000, in terms of polystyrene equivalent molecular weight as measured by GPC. Among these, the number average molecular weight is preferably 7,000 or less, since a graft copolymer with low viscosity can be obtained. Furthermore, the number average molecular weight is preferably 4,000 or less, since good adhesiveness can be exhibited even at low viscosity.

[0091] The weight-average molecular weight of the graft copolymer is not particularly limited, but is preferably 500 to 80,000, more preferably 3,000 to 70,000, and particularly preferably 5,000 to 65,000, as measured by GPC in terms of polystyrene. Of these, a weight-average molecular weight of 40,000 or less is preferred, as this allows for the production of a cured product with low viscosity and high strength.

[0092] The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the graft copolymer is not particularly limited, but from the viewpoint of making the graft copolymer have a low viscosity, it is preferably 3.5 or more and 10 or less, and more preferably 4.5 or more and 8 or less.

[0093] The number average molecular weight (Mn) and weight average molecular weight (Mw) of the graft copolymer are values ​​measured by gel permeation chromatography (GPC) in terms of polystyrene. Detailed measurement methods are described in the Examples. As described above, the graft copolymer may contain a polymer component in which the block (A) and the block (B) are not bonded to each other. The number average molecular weight, weight average molecular weight, and molecular weight distribution of the graft copolymer are values ​​measured for the graft copolymer including such a polymer component.

[0094] <Method for Producing Graft Copolymer> The graft copolymer according to this embodiment can be produced by subjecting a (meth)acrylic acid ester (a1), a chain transfer agent (a2) having a mercapto group, any other monomer (a3), and a polyfunctional macromonomer (a4) to a polymerization reaction. The polymerization method is not particularly limited, but may be a general free radical polymerization. According to this embodiment, despite being free radical polymerization, it is possible to control the polymerization, produce a graft copolymer, and further, make the molecular weight distribution of the graft copolymer relatively narrow.

[0095] Examples of polymerization initiators that can be used in the free radical polymerization include azo compounds such as 2,2'-azobis(2-methylbutyronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], and 1,1'-azobis(cyclohexane-1-carbonitrile). Diacyl peroxides such as benzoyl peroxide, isobutyryl peroxide, isononanoyl peroxide, decanoyl peroxide, lauroyl peroxide, parachlorobenzoyl peroxide, and di(3,5,5-trimethylhexanoyl) peroxide; diisopropyl percarbonate, di-sec-butyl percarbonate, di-2-ethylhexyl percarbonate, di-1-methylheptyl percarbonate, and di-3-methoxybutyl percarbonate peroxydicarbonates such as tert-butyl perbenzoate, tert-butyl peracetate, tert-butyl per-2-ethylhexanoate, tert-butyl perisobutyrate, tert-butyl perpivalate, tert-butyl diperadipate, and cumyl perneodecanoate; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxides such as di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, and 1,1-di(tert-hexylperoxy)-3,3,5-trimethylcyclohexane; hydroperoxides such as cumene hydroxyperoxide and tert-butyl hydroperoxide; and peroxides such as 1,1-di(tert-hexylperoxy)-3,3,5-trimethylcyclohexane. These polymerization initiators may be used alone or in combination of two or more.

[0096] Examples of solvents that can be used in the free radical polymerization include aromatic solvents such as toluene, xylene, styrene, ethylbenzene, paradichlorobenzene, di-2-ethylhexyl phthalate, and di-n-butyl phthalate; aliphatic hydrocarbon solvents such as hexane, heptane, octane, cyclohexane, and methylcyclohexane; carboxylic acid ester compounds such as ethyl acetate, butyl acetate, n-propyl acetate, and isopropyl acetate; ketone compounds such as methyl isobutyl ketone and methyl ethyl ketone; dialkyl carbonate compounds such as dimethyl carbonate and diethyl carbonate; and alcohol compounds such as n-propanol, 2-propanol, n-butanol, 2-butanol, isobutanol, tert-butanol, and amyl alcohol. Since the resulting graft copolymer tends to be difficult to dissolve in alcoholic solvents, it is preferable to use a non-alcoholic solvent. In particular, it is preferable to use a carboxylic acid ester solvent. Aromatic solvents are preferred due to their high dissolving power.

[0097] As described above, the graft copolymer has a reactive silicon group by using a (meth)acrylic acid ester having a reactive silicon group or by using a chain transfer agent having a reactive silicon group in addition to a mercapto group. Both methods may be used in combination. By using a (meth)acrylic acid ester having a reactive silicon group, reactive silicon groups can be introduced randomly into the side chains of the (meth)acrylic acid ester-based polymer block (A). Furthermore, by using a chain transfer agent having a reactive silicon group in addition to a mercapto group, reactive silicon groups can be introduced into the terminals of the (meth)acrylic acid ester-based polymer block (A).

[0098] However, the following methods can also be used in combination to further introduce reactive silicon groups into the graft copolymer. (i) A method in which a monomer having a reactive functional group (V group) is copolymerized with a (meth)acrylic acid ester (a1) or the like, and then the resulting copolymer is reacted with a compound having a functional group reactive with the V group and a reactive silicon group. Specific examples include a method in which 2-hydroxyethyl acrylate is copolymerized and then reacted with an isocyanate silane compound having a reactive silicon group, and a method in which glycidyl acrylate is copolymerized and then reacted with an aminosilane compound having a reactive silicon group. (ii) A method in which the terminal functional group of a (meth)acrylic acid ester polymer synthesized by living radical polymerization is modified to introduce reactive silicon groups. Functional groups can be easily introduced into the polymer terminals of (meth)acrylic acid ester polymers obtained by living radical polymerization, and by modifying the polymer, reactive silicon groups can be introduced into the polymer terminals.

[0099] Examples of the compound having a functional group reactive with the V group and a reactive silicon group used in the method (i) include isocyanate silane compounds such as 3-isocyanatepropyldimethoxymethylsilane, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, isocyanatemethyldimethoxymethylsilane, isocyanatemethyltrimethoxysilane, and isocyanatemethyltriethoxysilane; 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and glycidoxymethylsilane; and epoxy silane compounds such as 3-aminopropyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, aminomethyldimethoxymethylsilane, aminomethyltrimethoxysilane, aminomethyltriethoxysilane, N-cyclohexylaminomethyldimethoxymethylsilane, N-cyclohexylaminomethyltrimethoxysilane, and N-cyclohexylaminomethyltriethoxysilane.

[0100] In the method (ii), any modification reaction can be used. Examples include a method using a compound having a reactive silicon group and a reactive group capable of reacting with a terminal functional group obtained by living radical polymerization, and a method in which a double bond is introduced into the polymer terminal using a compound having a reactive group and a double bond capable of reacting with a terminal functional group, and then a reactive silicon group is introduced using a hydrosilylation reaction or the like.

[0101] <<Curable Composition>> The graft copolymer according to this embodiment can be used in a curable composition. The curable composition preferably contains a silanol condensation catalyst to promote the condensation reaction of the reactive silicon groups in the graft copolymer.

[0102] <Silanol Condensation Catalyst> Examples of silanol condensation catalysts include organotin compounds, metal carboxylates, amine compounds, carboxylic acids, and alkoxy metals.

[0103] Specific examples of organotin compounds include dibutyltin dilaurate, dibutyltin dioctanoate, dibutyltin bis(butyl maleate), dibutyltin diacetate, dibutyltin oxide, dibutyltin bis(acetylacetonate), dioctyltin bis(acetylacetonate), dioctyltin dilaurate, dioctyltin distearate, dioctyltin diacetate, dioctyltin oxide, a reaction product of dibutyltin oxide with a silicate compound, a reaction product of dioctyltin oxide with a silicate compound, and a reaction product of dibutyltin oxide with a phthalate ester.

[0104] Specific examples of the metal carboxylate include tin carboxylate, bismuth carboxylate, titanium carboxylate, zirconium carboxylate, iron carboxylate, etc. The metal carboxylate can be a combination of the following carboxylic acids and various metals.

[0105] Specific examples of the amine compound include amines such as octylamine, 2-ethylhexylamine, laurylamine, and stearylamine; nitrogen-containing heterocyclic compounds such as pyridine, 1,8-diazabicyclo[5,4,0]undecene-7 (DBU), and 1,5-diazabicyclo[4,3,0]nonene-5 (DBN); guanidines such as guanidine, phenylguanidine, and diphenylguanidine; biguanides such as butylbiguanide, 1-o-tolylbiguanide, and 1-phenylbiguanide; amino group-containing silane coupling agents; and ketimine compounds.

[0106] Specific examples of carboxylic acids include acetic acid, propionic acid, butyric acid, 2-ethylhexanoic acid, lauric acid, stearic acid, oleic acid, linoleic acid, neodecanoic acid, and versatic acid.

[0107] Specific examples of alkoxy metals include titanium compounds such as tetrabutyl titanate titanium tetrakis(acetylacetonate) and diisopropoxytitanium bis(ethylacetoacetate), aluminum compounds such as aluminum tris(acetylacetonate) and diisopropoxyaluminum ethylacetoacetate, and zirconium compounds such as zirconium tetrakis(acetylacetonate).

[0108] When a silanol condensation catalyst is used, the amount used is preferably 0.001 to 20 parts by weight, more preferably 0.01 to 15 parts by weight, and even more preferably 0.01 to 10 parts by weight, relative to 100 parts by weight of the graft copolymer according to this embodiment, from the viewpoint of promoting the condensation reaction of the reactive silicon groups.

[0109] <<Other Additives>> In addition to the graft copolymer and silanol condensation catalyst according to this embodiment, the curable composition according to this embodiment may contain additives such as a plasticizer, a filler, an adhesion promoter, a dehydrating agent, a rheology control agent, an antioxidant, a light stabilizer, an ultraviolet absorber, and other resins.

[0110] Furthermore, various additives may be added to the curable composition according to this embodiment as needed for the purpose of adjusting the physical properties of the curable composition or the cured product. Examples of such additives include solvents, diluents, photocurable substances, oxygen-curable substances, surface property improvers, silicates, curability regulators, radical inhibitors, metal deactivators, antiozonants, phosphorus-based peroxide decomposers, lubricants, pigments, mildew inhibitors, flame retardants, and foaming agents.

[0111] <Plasticizer> The curable composition may contain a plasticizer. By incorporating a plasticizer, the viscosity of the curable composition can be reduced, making it easier to handle.

[0112] The plasticizer is not particularly limited, and examples thereof include phthalate ester compounds such as dibutyl phthalate, diisononyl phthalate (DINP), diheptyl phthalate, di(2-ethylhexyl) phthalate, diisodecyl phthalate (DIDP), and butyl benzyl phthalate; terephthalate ester compounds such as bis(2-ethylhexyl)-1,4-benzenedicarboxylate; non-phthalate ester compounds such as 1,2-cyclohexanedicarboxylic acid diisononyl ester; and fatty acids such as dioctyl adipate, dioctyl sebacate, dibutyl sebacate, diisodecyl succinate, and acetyl tributyl citrate. chlorinated paraffins; hydrocarbon oils such as alkyl diphenyls and partially hydrogenated terphenyls; process oils; epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, bis(2-ethylhexyl)-4,5-epoxycyclohexane-1,2-dicarboxylate (E-PS), epoxy octyl stearate, epoxy butyl stearate, and epoxy benzyl stearate; alkyl sulfonic acid esters, and the like.

[0113] As the plasticizer, a polymer plasticizer can also be used. Specific examples of polymer plasticizers include vinyl polymers; polyester plasticizers; polyether polyols such as polyethylene glycol and polypropylene glycol having a number average molecular weight of 500 or more, and polyether plasticizers such as derivatives in which the hydroxy groups of these polyether polyols are converted into ester groups, ether groups, etc.; polystyrenes; polybutadiene, polybutene, polyisobutylene, butadiene-acrylonitrile, polychloroprene, etc. Among these, polymer plasticizers are preferred, polyether plasticizers are more preferred, and polypropylene glycol is particularly preferred. As the plasticizer, only one type may be used, or two or more types may be used in combination.

[0114] The amount of the plasticizer to be added is preferably 5 to 150 parts by weight, more preferably 10 to 120 parts by weight, and particularly preferably 20 to 100 parts by weight, per 100 parts by weight of the graft copolymer.

[0115] <Filler> The curable composition may contain a filler, which can improve the strength of the cured product.

[0116] Examples of fillers include heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, diatomaceous earth, clay, talc, titanium oxide, fumed silica, precipitated silica, crystalline silica, fused silica, anhydrous silicic acid, hydrous silicic acid, alumina, carbon black, ferric oxide, fine aluminum powder, zinc oxide, activated zinc white, PVC powder, PMMA powder, glass fiber, and filaments. Organic balloons and inorganic balloons may be added to reduce the weight (specific gravity) of the composition. Only one type of filler may be used, or two or more types may be used in combination.

[0117] The amount of the filler to be blended is preferably 1 to 300 parts by weight, more preferably 10 to 250 parts by weight, per 100 parts by weight of the graft copolymer.

[0118] <Adhesion Imparting Agent> The curable composition may contain an adhesion imparting agent. As the adhesion imparting agent, a silane coupling agent or a reaction product of a silane coupling agent may be added.

[0119] Specific examples of the silane coupling agent include amino group-containing silanes such as γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and (2-aminoethyl)aminomethyltrimethoxysilane; γ-isocyanatepropyltrimethoxysilane, γ-isocyanatepropyltriethoxysilane, and γ-isopropyltriethoxysilane; Examples of suitable adhesives include isocyanate group-containing silanes such as cyanatepropylmethyldimethoxysilane, α-isocyanatomethyltrimethoxysilane, and α-isocyanatomethyldimethoxymethylsilane; mercapto group-containing silanes such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and γ-mercaptopropylmethyldimethoxysilane; and epoxy group-containing silanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Reaction products of various silane coupling agents can also be used. The adhesion promoter may be used alone or in combination with two or more types.

[0120] The amount of the adhesion promoter to be added is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the graft copolymer.

[0121] <Dehydrating Agent> A dehydrating agent can be added to the curable composition. Here, the dehydrating agent is preferably a compound capable of reacting with water, more preferably a silicon compound capable of reacting with water (excluding compounds that fall under the category of adhesion promoters), and particularly preferably a trialkoxysilane compound.

[0122] Specific examples of the dehydrating agent include, but are not limited to, vinyl group-containing silanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, etc. Only one type of dehydrating agent may be used, or two or more types may be used.

[0123] The amount of the dehydrating agent to be added is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, and even more preferably 1 to 5 parts by weight, based on 100 parts by weight of the graft copolymer.

[0124] <Rheology Control Agent> A rheology control agent may be added to the curable composition as needed to prevent sagging and improve workability.

[0125] The rheology control agent is not particularly limited, but examples thereof include fatty acid amide waxes, hydrogenated castor oil derivatives, metal soaps such as calcium stearate, aluminum stearate, and barium stearate, dry silica, wet silica, etc. These rheology control agents may be used alone or in combination of two or more.

[0126] The amount of the rheology control agent to be added is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the graft copolymer.

[0127] <Antioxidant> An antioxidant (antiaging agent) can be used in the curable composition. The use of an antioxidant can improve the weather resistance of the cured product. Examples of antioxidants include hindered phenols, monophenols, bisphenols, and polyphenols. Specific examples of antioxidants are also described in JP-A-4-283259 and JP-A-9-194731. The amount of antioxidant added is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the graft copolymer.

[0128] <Light Stabilizer> A light stabilizer can be used in the curable composition. The use of a light stabilizer can prevent photooxidative degradation of the cured product. Examples of light stabilizers include benzotriazole-based, hindered amine-based, and benzoate-based compounds, with hindered amine-based compounds being particularly preferred. The amount of light stabilizer added is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the graft copolymer.

[0129] <Ultraviolet Absorber> An ultraviolet absorber can be used in the curable composition. Use of an ultraviolet absorber can improve the surface weather resistance of the cured product. Examples of ultraviolet absorbers include benzophenone-based, benzotriazole-based, salicylate-based, substituted tolyl-based, and metal chelate-based compounds, with benzotriazole-based absorbers being particularly preferred, and examples thereof include those commercially available under the names Tinuvin P, Tinuvin 213, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 329, and Tinuvin 571 (all manufactured by BASF). The amount of ultraviolet absorber added is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the graft copolymer.

[0130] The curable composition according to one embodiment of the present invention can be prepared as a one-component composition in which all components are mixed in advance and stored in a sealed container, and the composition is cured by moisture in the air after application. In this case, it is preferable to dehydrate and dry the components containing water before use, or to dehydrate them by reducing the pressure during mixing and kneading.

[0131] Furthermore, the curable composition according to one embodiment of the present invention is composed of a base agent containing a graft copolymer and a curing agent containing components such as a silanol condensation catalyst, a filler, a plasticizer, and water, and can also be prepared as a two-component composition in which the base agent and the curing agent are mixed before use.

[0132] The method for preparing the curable composition according to one embodiment of the present invention is not particularly limited. For example, a common method may be used, such as blending the above components and kneading them at room temperature or under heat using a mixer, roll, kneader, or the like, or dissolving the above components in a small amount of an appropriate solvent and mixing them.

[0133] The curable composition according to one embodiment of the present invention exhibits good adhesion to various adherends, including plastics, metals, and composites. Furthermore, when used as an adhesive for nonpolar materials such as polypropylene or engineering plastics with rigid molecular chains such as polyphenylene sulfide, the adherends can be pre-surface-treated by a known method to enhance adhesion to these adherends and obtain stable adhesive strength. For example, surface treatment techniques such as sanding, flame treatment, corona discharge, arc discharge, and plasma treatment can be used. Plasma treatment is preferred because it causes minimal damage to the adherend and provides stable adhesion. These surface treatments are also effective for removing release agents remaining on the adherend surface after molding.

[0134] The cured product obtained by curing the curable composition according to one embodiment of the present invention has good adhesion to various adherends, and therefore the curable composition can be used as an adhesive, a sealant, or a pressure-sensitive adhesive. In particular, the curable composition according to one embodiment of the present invention is solid at room temperature, but becomes fluid when heated and melted, making it possible to apply it to a substrate, and therefore can be suitably used as a hot-melt curable composition, particularly a hot-melt adhesive.

[0135] In order to ensure workability when applying the curable composition according to one embodiment of the present invention to an adherend, it is preferable to heat the composition to a high temperature to reduce the viscosity, and the temperature at that time is preferably about 70 to 180° C., more preferably 90 to 160° C., and even more preferably 100 to 150° C. The heating method is not particularly limited, and a conventionally known method can be used.

[0136] The curable composition according to one embodiment of the present invention can exhibit the desired physical properties by being subjected to a long-term curing (aging) step after bonding the adherends. The conditions for the curing (aging) step are not particularly limited, but examples include a temperature of 5 to 90°C and a time of 24 hours to 1 week.

[0137] When the curable composition according to one embodiment of the present invention is used as a hot-melt curable composition, it can be used as a reactive hot-melt adhesive. This curable composition is suitable for use as an adhesive for joining panels of buses, trailers, trains, etc., as an adhesive for connecting displays and housings in smartphones, tablet devices, laptops, etc., and for joining dissimilar materials such as aluminum-steel, steel-composite materials, and aluminum-composite materials. When joining dissimilar materials, it is preferable to cover the joint with a sealer to prevent corrosion. Polymers having reactive silicon groups, as described herein, can be used as the sealer.

[0138] More specifically, the curable composition according to one embodiment of the present invention is preferably used as an adhesive for automobile parts such as vehicle panels, large vehicle parts such as trucks and buses, train parts, aircraft parts, ship parts, electrical parts, various machine parts, and the like.

[0139] In the following items, preferred embodiments of the present disclosure are listed, but the present invention is not limited to the following items. [Item 1] General formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １ represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. X represents a hydroxyl group or a hydrolyzable group. a represents 2 or 3. A graft copolymer in which a (meth)acrylic acid ester-based polymer block (A) having a reactive silicon group represented by the following formula (1): and a hydrocarbon-based polymer block (B) are bonded in the order A-B-A, wherein the content of the (meth)acrylic acid alkyl ester having an alkyl carbon number of 4 or more is 10% by weight or more in the graft copolymer. [Item 2] General formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. X represents a hydroxyl group or a hydrolyzable group. a represents 2 or 3. A graft copolymer in which a (meth)acrylic acid ester-based polymer block (A) having a reactive silicon group represented by the following formula (I) and a hydrocarbon-based polymer block (B) are bonded in the order A-B-A, wherein the (meth)acrylic acid ester-based polymer block (A) contains a structural unit derived from a chain transfer agent (a2) having a mercapto group, and the molar ratio of the hydrocarbon-based polymer block (B) to the chain transfer agent (a2) having a mercapto group is 0.06 or more. [Item 3] The graft copolymer according to Item 1 or 2, in which the hydrocarbon-based polymer block (B) is at least one selected from the group consisting of a polyisobutylene-based polymer, a polybutadiene-based polymer, and a hydrogenated polybutadiene-based polymer. [Item 4] The graft copolymer according to any one of items 1 to 3, wherein the proportion of the polymer block (A) is 30 to 85% by weight and the proportion of the polymer block (B) is 15 to 70% by weight. [Item 5] The graft copolymer according to any one of items 1 to 4, wherein the molecular weight distribution (Mw / Mn) of the graft copolymer is 3.5 or more and 10 or less. [Item 6] The graft copolymer according to any one of items 1 to 5, wherein the graft copolymer contains sulfur atoms and has a sulfur atom concentration of 2,000 to 15,000 ppm. [Item 7] A curable composition comprising the graft copolymer according to any one of items 1 to 6. [Item 8] A hot-melt adhesive comprising the graft copolymer according to any one of items 1 to 6.

[0140] The present invention will be specifically explained below by way of examples, but the present invention is not limited to these examples.

[0141] The number average molecular weight and weight average molecular weight in the examples are GPC molecular weights measured under the following conditions: Solution delivery system: HLC-8120GPC manufactured by Tosoh Corporation Column: TSK-GEL H type manufactured by Tosoh Corporation Solvent: THF Molecular weight: Polystyrene equivalent Measurement temperature: 40°C

[0142] (Sulfur Atom Concentration) The sulfur atom concentration is a theoretical value calculated from the total amount of the constituent components used in the production of the graft copolymer and the amount of the chain transfer agent (a2) having a mercapto group.

[0143] Synthesis Example 1 A four-neck flask equipped with a stirrer was charged with 44.4 parts by weight of toluene, and the temperature was raised to 110° C. under a nitrogen atmosphere. A mixed solution prepared by dissolving 5.0 parts by weight of methyl methacrylate, 38.0 parts by weight of butyl acrylate, 15.0 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 3-methacryloxypropyldimethoxymethylsilane, 4.0 parts by weight of 3-mercaptopropyldimethoxymethylsilane, 35.0 parts by weight of a polyfunctional macromonomer (a polyisobutylene macromonomer having an average of two acryloyl groups per molecule, a number average molecular weight of 14,650, and a molecular weight distribution of 1.16, product name: EP-400V, manufactured by Kaneka Corporation), and 0.5 parts by weight of 2,2′-azobis(2-methylbutyronitrile) in 12.0 parts by weight of toluene was added dropwise thereto over 3 hours. A mixed solution of 0.35 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 10.9 parts by weight of toluene was then added, and polymerization was carried out for 2 hours at 110°C to obtain a toluene solution (solids content 60%) of reactive silicon group-containing graft copolymer (C-1) having a number average molecular weight of 4,550 (GPC molecular weight). The solid content of the solution had a polyfunctional macromonomer equivalent of 0.028 mmol / g, a reactive silicon group equivalent of 0.35 mmol / g, and a sulfur atom concentration of 7,099 ppm.

[0144] Synthesis Example 2 A four-neck flask equipped with a stirrer was charged with 44.4 parts by weight of toluene, and the temperature was raised to 110° C. under a nitrogen atmosphere. A mixed solution prepared by dissolving 5.0 parts by weight of methyl methacrylate, 28.3 parts by weight of butyl acrylate, 10.0 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 3-methacryloxypropyldimethoxymethylsilane, 14.7 parts by weight of isobornyl acrylate, 4.0 parts by weight of 3-mercaptopropyldimethoxymethylsilane, 35.0 parts by weight of a polyfunctional macromonomer (a polyisobutylene macromonomer having an average of two acryloyl groups per molecule, a number average molecular weight of 14,650, and a molecular weight distribution of 1.16, product name: EP-400V, manufactured by Kaneka Corporation), and 0.5 parts by weight of 2,2′-azobis(2-methylbutyronitrile) in 12.0 parts by weight of toluene was added dropwise thereto over 3 hours. A mixed solution of 0.35 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 10.9 parts by weight of toluene was then added and polymerization was carried out for 2 hours at 110°C to obtain a toluene solution (solids content 60%) of reactive silicon group-containing graft copolymer (C-2) having a number average molecular weight of 3,800 (GPC molecular weight). The solid content of the solution had a polyfunctional macromonomer equivalent of 0.028 mmol / g, a reactive silicon group equivalent of 0.35 mmol / g, and a sulfur atom concentration of 7,099 ppm.

[0145] Synthesis Example 3 A four-neck flask equipped with a stirrer was charged with 44.4 parts by weight of toluene, and the temperature was raised to 110° C. under a nitrogen atmosphere. A mixed solution prepared by dissolving 5.0 parts by weight of methyl methacrylate, 38.0 parts by weight of butyl acrylate, 15.0 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 3-methacryloxypropyldimethoxymethylsilane, 4.0 parts by weight of 3-mercaptopropyldimethoxymethylsilane, 35.0 parts by weight of a multifunctional macromonomer (a hydrogenated polybutadiene macromonomer having an average of two acryloyl groups per molecule, a number average molecular weight of 4,060, and a molecular weight distribution of 1.64, trade name: TEAI-1000, manufactured by Nippon Soda Co., Ltd.), and 0.5 parts by weight of 2,2′-azobis(2-methylbutyronitrile) in 12.0 parts by weight of toluene was added dropwise thereto over 3 hours. A mixed solution of 0.35 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 10.9 parts by weight of toluene was then added and polymerization was carried out at 110°C for 2 hours to obtain a toluene solution (solids content 60%) of reactive silicon group-containing graft copolymer (C-3) having a number average molecular weight of 4,380 (GPC molecular weight). The solid content of the solution had a polyfunctional macromonomer equivalent of 0.086 mmol / g, a reactive silicon group equivalent of 0.35 mmol / g, and a sulfur atom concentration of 7,099 ppm.

[0146] Synthesis Example 4 A four-neck flask equipped with a stirrer was charged with 44.4 parts by weight of toluene, and the temperature was raised to 110° C. under a nitrogen atmosphere. A mixed solution prepared by dissolving 10.0 parts by weight of butyl acrylate, 3.0 parts by weight of 3-methacryloxypropyldimethoxymethylsilane, 48.0 parts by weight of isobornyl acrylate, 4.0 parts by weight of 3-mercaptopropyldimethoxymethylsilane, 35.0 parts by weight of a polyfunctional macromonomer (a polyisobutylene macromonomer having an average of two acryloyl groups per molecule, a number average molecular weight of 14,650, and a molecular weight distribution of 1.16, product name: EP-400V, manufactured by Kaneka Corporation), and 0.5 parts by weight of 2,2′-azobis(2-methylbutyronitrile) in 12.0 parts by weight of toluene was added dropwise thereto over 3 hours. A mixed solution of 0.35 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 10.9 parts by weight of toluene was then added, and polymerization was carried out at 110°C for 2 hours to obtain a toluene solution (solids content 60%) of reactive silicon group-containing graft copolymer (C-4) having a number average molecular weight of 3,260 (GPC molecular weight). The solid content of the solution had a polyfunctional macromonomer equivalent of 0.028 mmol / g, a reactive silicon group equivalent of 0.35 mmol / g, and a sulfur atom concentration of 7,099 ppm.

[0147] Comparative Synthesis Example 1 21.1 parts by weight of toluene was placed in a four-neck flask equipped with a stirrer and heated to 110°C under a nitrogen atmosphere. A mixed solution containing 5.0 parts by weight of methyl methacrylate, 38.0 parts by weight of butyl acrylate, 15.0 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 3-methacryloxypropyldimethoxymethylsilane, 4.0 parts by weight of 3-mercaptopropyldimethoxymethylsilane, and 0.5 parts by weight of 2,2'-azobis(2-methylbutyronitrile) dissolved in 12.0 parts by weight of toluene was added dropwise over 3 hours. A mixed solution containing 0.35 parts by weight of 2,2'-azobis(2-methylbutyronitrile) dissolved in 10.9 parts by weight of toluene was then added, and polymerization was carried out at 110°C for 2 hours to obtain a toluene solution (solids content 60%) of a reactive silicon group-containing (meth)acrylic acid ester polymer (P-1) having a number average molecular weight of 2,390 (GPC molecular weight). The polymer had a reactive silicon group equivalent of 0.54 mmol / g and a sulfur atom concentration of 11,003 ppm.

[0148] Comparative Synthesis Example 2 A four-neck flask equipped with a stirrer was charged with 44.4 parts by weight of toluene, and the temperature was raised to 110° C. under a nitrogen atmosphere. A mixed solution prepared by dissolving 5.0 parts by weight of methyl methacrylate, 47.8 parts by weight of butyl acrylate, 10.0 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 3-methacryloxypropyldimethoxymethylsilane, 14.7 parts by weight of isobornyl acrylate, 4.5 parts by weight of 3-mercaptopropyldimethoxymethylsilane, 15.0 parts by weight of a polyfunctional macromonomer (a polyisobutylene macromonomer having an average of two acryloyl groups per molecule, a number average molecular weight of 14,650, and a molecular weight distribution of 1.16, product name: EP-400V, manufactured by Kaneka Corporation), and 0.5 parts by weight of 2,2′-azobis(2-methylbutyronitrile) in 12.0 parts by weight of toluene was added dropwise thereto over 3 hours. A mixed solution of 0.35 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 10.9 parts by weight of toluene was then added, and polymerization was carried out for 2 hours at 110°C to obtain a toluene solution (solids content 60%) of reactive silicon group-containing graft copolymer (P-2) having a number average molecular weight of 3,200 (GPC molecular weight). The solid content of the solution had a polyfunctional macromonomer equivalent of 0.012 mmol / g, a reactive silicon group equivalent of 0.35 mmol / g, and a sulfur atom concentration of 7,987 ppm.

[0149] Example 1 The toluene solution of the graft copolymer obtained in Synthesis Example 1 was heated and devolatilized to obtain a graft polymer (C-1).

[0150] (Viscosity) Using parallel circular plates with a diameter of 20 mm as a jig, the gap was set to 0.3 mm, and the temperature was 23°C and the shear rate was 1 x 10 －３ The viscosity was measured while increasing from 0.01 (1 / sec) to 100 (1 / sec) over 7 minutes. A TA Instruments rheometer (DHR-2) was used. The viscosity was read at a shear rate of 0.01 (1 / sec) or 10 (1 / sec). The viscosity ratio was calculated from [viscosity at 0.01 (1 / sec) / viscosity at 10 (1 / sec)]. The results are shown in Table 1.

[0151] (Tensile Properties) 100 parts by weight of the polymer was heated to 60°C, and 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.8 parts by weight of U-130 (dibutyltin oxylaurate, manufactured by Nitto Kasei Co., Ltd.) were added and mixed to prepare a sheet having a thickness of approximately 1 mm. The sheet was aged for 4 days at 23°C and 50% RH, for 1 day at 50°C and 95% RH, and for 1 day at 50°C. The obtained sheet was punched into a No. 3 dumbbell shape (JIS K 6251) and subjected to a tensile strength test at an elongation rate of 50 mm / min to measure the strength at break (TB). The apparatus used was an autograph (AGS-X) manufactured by Shimadzu Corporation. The results are shown in Table 1.

[0152] (Water Vapor Permeability) 100 parts by weight of the polymer was heated to 60°C, and 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.8 parts by weight of U-130 (dibutyltin oxylaurate, manufactured by Nitto Kasei Co., Ltd.) were added and mixed to prepare a sheet having a thickness of approximately 1 mm. The sheet was aged for 4 days at 23°C and 50% RH, for 1 day at 50°C and 95% RH, and for 1 day at 50°C. A 70 mmφ test piece was punched out from the obtained sheet to prepare a moisture-permeable cup as described in JIS Z0208 (Test method for moisture permeability of moisture-proof packaging materials). The prepared moisture-permeable cup was left for 2 days at 40°C and 90% RH. The moisture permeability was calculated using the following formula. Formula: Moisture permeability (g / m ２ 24 hr) = 240 × (weight of moisture permeability cup after 2 days (mg) - initial weight of moisture permeability cup (mg)) / 48 hr / moisture permeability area (cm ２ )

[0153] The toluene solutions of the graft copolymers obtained in Synthesis Examples 2 and 3 were heated and devolatilized to obtain graft polymers (C-2) to (C-3) in the same manner as in Example 1, and the respective evaluations were carried out in the same manner. The results are shown in Table 1.

[0154] Comparative Example 1 A reactive silicon group-containing acrylic ester polymer (product name: SA100S, manufactured by Kaneka Corporation) not containing the hydrocarbon polymer block (B) was evaluated as follows: (Viscosity) The evaluation was carried out in the same manner as in Example 1.

[0155] (Tensile Properties) 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.8 parts by weight of U-130 (dibutyltin oxylaurate, manufactured by Nitto Kasei Co., Ltd.) were added to 100 parts by weight of the polymer and mixed to prepare a sheet having a thickness of approximately 1 mm. The sheet was aged for 4 days at 23°C and 50% RH, for 1 day at 50°C and 95% RH, and for 1 day at 50°C. The obtained sheet was punched into a No. 3 dumbbell shape (JIS K 6251) and subjected to a tensile strength test at an elongation rate of 50 mm / min to measure the strength at break (TB). The apparatus used was an autograph (AGS-X) manufactured by Shimadzu Corporation. The results are shown in Table 1.

[0156] (Water Vapor Permeability) 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.8 parts by weight of U-130 (dibutyltin oxylaurate, manufactured by Nitto Kasei Co., Ltd.) were added to 100 parts by weight of the polymer and mixed to prepare a sheet having a thickness of approximately 1 mm. The sheet was aged for 4 days at 23°C and 50% RH, for 1 day at 50°C and 95% RH, and for 1 day at 50°C. A 70 mmφ test piece was punched out from the obtained sheet to prepare a moisture-permeable cup according to JIS Z0208 (Moisture-Permeability Test Method for Moisture-Proof Packaging Materials). The prepared moisture-permeable cup was left for 2 days at 40°C and 90% RH. The moisture permeability was calculated using the above formula.

[0157] Comparative Example 2 A toluene solution of the (meth)acrylic acid ester polymer (P-1) obtained in Comparative Synthesis Example 1 was heated and devolatilized. 65 parts by weight of the obtained polymer was mixed with 35.0 parts by weight of a polyfunctional macromonomer (a polyisobutylene macromonomer having an average of two acryloyl groups per molecule and a number average molecular weight of 14,650, product name: EP-400V, manufactured by Kaneka Corporation) to prepare a polymer blend composition. The polymer blend composition was cloudy and incompatible. To 100 parts by weight of this polymer blend, 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.8 parts by weight of U-130 (dibutyltin oxylaurate, manufactured by Nitto Kasei Co., Ltd.) were added and mixed, and a sheet approximately 1 mm thick was prepared. The sheet was aged for 4 days at 23°C and 50% RH, for 1 day at 50°C and 95% RH, and for 1 day at 50°C. The resulting cured product was very brittle, and it was not possible to prepare samples for evaluating tensile properties and water vapor permeability.

[0158] Comparative Example 3 A mixed monomer solution containing 63.5 parts by weight of methyl methacrylate, 8.0 parts by weight of butyl acrylate, 3.0 parts by weight of 3-methacryloxypropyldimethoxymethylsilane, 5.5 parts by weight of 3-mercaptopropyldimethoxymethylsilane, 20.0 parts by weight of a polyfunctional macromonomer (a polyisobutylene macromonomer having an average of two acryloyl groups per molecule, a number average molecular weight of 14,650, and a molecular weight distribution of 1.16, product name: EP-400V, manufactured by Kaneka Corporation), and 0.5 parts by weight of 2,2′-azobis(2-methylbutyronitrile) dissolved in 12.0 parts by weight of toluene was prepared, but the monomers and the polyfunctional macromonomer were not compatible with each other. As a result, it was not possible to carry out a polymerization reaction to produce a graft copolymer.

[0159]

[0160] The following can be seen from Table 1: In Examples 1 to 3, which relate to graft copolymers in which a reactive silicon group-containing (meth)acrylic ester polymer block (A) and a hydrocarbon polymer block (B) are bonded in the order A-B-A, the viscosity ratios are greater than 1, indicating high thixotropy, the water vapor permeability is low, indicating low moisture permeability, and the breaking strength after curing is high, compared to Comparative Example 1, in which a reactive silicon group-containing acrylic ester polymer not containing a hydrocarbon polymer block (B) was evaluated.

[0161] Comparative Example 2 shows that when a (meth)acrylic acid ester polymer having a reactive silicon group and a hydrocarbon polymer are simply blended without grafting, the compatibility of the two polymers is low, and a good cured product cannot be formed after the reactive silicon group-containing polymer is reacted.

[0162] Comparative Example 3 shows that when the content of the (meth)acrylic acid alkyl ester having an alkyl group with 4 or more carbon atoms (butyl acrylate in this case) is less than 10% by weight, a graft copolymer cannot be produced.

[0163] From Comparative Example 4, it can be seen that when the molar ratio of hydrocarbon polymer block (B) / chain transfer agent (a2) having a mercapto group is less than 0.06, the breaking strength after curing is small.

[0164] Example 4 The toluene solution of the graft copolymer obtained in Synthesis Example 4 was heated and devolatilized to obtain a graft polymer (C-4).

[0165] (Complex Viscosity and Complex Modulus) For the obtained graft copolymer (C-4), dynamic viscoelasticity measurement was carried out using parallel circular plates with a diameter of 20 mm as a jig, with a gap set to 0.5 mm, while the temperature was lowered from 150°C to 10°C. The complex viscosity value at 120°C was recorded, and the complex modulus value at 23°C was recorded. The results are shown in Table 2. A rheometer (DHR-2) manufactured by TA Instruments was used as the apparatus.

[0166] (Tensile Properties) 100 parts by weight of the polymer was heated to 140°C and melted, and 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.8 parts by weight of U-130 (dibutyltin oxylaurate, manufactured by Nitto Kasei Co., Ltd.) were added and mixed to prepare a sheet having a thickness of approximately 1 mm. The sheet was aged for 4 days at 23°C and 50% RH, for 1 day at 50°C and 95% RH, and for 1 day at 50°C. The obtained sheet was punched into a No. 3 dumbbell shape (JIS K 6251) and subjected to a tensile strength test at an elongation rate of 50 mm / min to measure the strength at break (TB). The apparatus used was an autograph (AGS-X) manufactured by Shimadzu Corporation. The results are shown in Table 2.

[0167]

[0168] From Table 2, it can be seen that the graft copolymer was evaluated as a hot melt adhesive and the breaking strength after curing was high.

Claims

1. General formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １ represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. X represents a hydroxyl group or a hydrolyzable group. a represents 2 or 3. A graft copolymer in which a (meth)acrylic acid ester-based polymer block (A) having a reactive silicon group represented by the following formula (I) and a hydrocarbon-based polymer block (B) are bonded in the order A-B-A, wherein the content of the (meth)acrylic acid alkyl ester having an alkyl group of 4 or more carbon atoms is 10% by weight or more in the graft copolymer.

2. General formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １ represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. X represents a hydroxyl group or a hydrolyzable group. a represents 2 or 3. A graft copolymer in which a (meth)acrylic acid ester-based polymer block (A) having a reactive silicon group represented by the following formula (I) and a hydrocarbon-based polymer block (B) are bonded in the order A-B-A, wherein the (meth)acrylic acid ester-based polymer block (A) contains a structural unit derived from a chain transfer agent (a2) having a mercapto group, and the molar ratio of the hydrocarbon-based polymer block (B) to the chain transfer agent (a2) having a mercapto group is 0.06 or more.

3. The graft copolymer according to claim 1 or 2, wherein the hydrocarbon polymer block (B) is at least one selected from the group consisting of polyisobutylene polymers, polybutadiene polymers, and hydrogenated polybutadiene polymers.

4. The graft copolymer according to claim 1 or 2, wherein the proportion of the polymer block (A) is 30 to 85% by weight, and the proportion of the polymer block (B) is 15 to 70% by weight.

5. The graft copolymer according to claim 1 or 2, wherein the molecular weight distribution (Mw / Mn) of the graft copolymer is 3.5 or more and 10 or less.

6. The graft copolymer according to claim 1 or 2, wherein the graft copolymer contains sulfur atoms and has a sulfur atom concentration of 2,000 to 15,000 ppm.

7. A curable composition comprising the graft copolymer of claim 1 or 2.

8. A hot melt adhesive comprising the graft copolymer according to claim 1 or 2.

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