Graft copolymers and curable compositions

Abstract

To provide a reactive silicon group-containing graft copolymer with low viscosity when heated and melted, a long bonding time after application, high initial adhesive strength after bonding, and good final physical properties of the cured product. [Solution] A graft copolymer comprising a (meth)acrylic acid ester polymer block (A) having reactive silicon groups and a polyoxyalkylene polymer block (B) having a number average molecular weight of 10,000 to 20,000 and a molecular weight distribution (Mw / Mn) of 1.0 to 1.5, bonded in the order ABA, wherein the proportion of polymer block (A) in the graft copolymer is 35 to 70% by weight and the proportion of polymer block (B) is 30 to 65% by weight, and the polymer block (A) contains constituent units derived from (meth)acrylic acid ester (a1) and constituent units derived from a chain transfer agent (a2) having mercapto groups.

Description

[Technical Field]

[0001] The present invention relates to a graft copolymer having a reactive silicon group, and a curable composition containing the polymer. [Background technology]

[0002] Organic polymers having silicon groups (hereinafter also referred to as "reactive silicon groups") that have a hydroxyl group or a hydrolyzable group on a silicon atom and can form siloxane bonds through hydrolysis and condensation reactions react even at room temperature due to moisture and other factors. It is known that rubbery cured products can be obtained when such organic polymers are crosslinked by the siloxane condensation reaction of reactive silicon groups.

[0003] Among these organic polymers, polyoxyalkylene polymers containing reactive silicon groups have relatively low viscosity, making them easy to work with when preparing and using compounded compositions. Furthermore, the resulting cured products have a good balance of mechanical properties, weather resistance, and dynamic durability, making them widely used in applications such as sealants, adhesives, and paints.

[0004] Furthermore, to improve the weather resistance and adhesion of polyoxyalkylene polymers having reactive silicon groups, curable compositions are also known that use a combination of a reactive silicon group-containing polyoxyalkylene polymer and a reactive silicon group-containing (meth)acrylic acid ester polymer.

[0005] Patent Document 1 describes a reactive silicon group-containing graft copolymer synthesized by radical polymerization of an oligomer having a polyether skeleton and double bonds at both ends, a vinyl monomer such as a (meth)acrylic acid ester, and a chain transfer agent, with the aim of overcoming the drawback of the slow curing speed of one-component moisture-curing adhesives containing modified silicone or acrylic-modified silicone. This copolymer has a fast curing speed and excellent adhesive properties.

[0006] Patent document 2 describes a method for producing such a reactive silicon group-containing graft copolymer by radical polymerization.

[0007] Patent Document 3 discloses that in a (meth)acrylic acid ester copolymer composed of a (meth)acrylic acid ester, a polyoxyalkylene polymer having one or more (meth)acryloyl groups in its molecule, and a chain transfer agent having mercapto groups, by setting the molar ratio of the polyoxyalkylene polymer to the chain transfer agent to 0.06 or higher, it is possible to achieve low viscosity while maintaining good physical properties after curing.

[0008] Patent documents 4 and 5 disclose that a hot-melt type curable composition can be constructed by using the (meth)acrylic acid ester copolymer in combination with a polyester having reactive silicon groups or a tackifying resin. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2007 / 023669 [Patent Document 2] Japanese Patent Publication No. 2005-15512 [Patent Document 3] International Publication No. 2022 / 203064 [Patent Document 4] Japanese Patent Publication No. 2023-100363 [Patent Document 5] International Publication No. 2023 / 132324 [Overview of the project] [Problems that the invention aims to solve]

[0010] Hot-melt adhesives are solid at room temperature but can be fluidized by heating and melting, enabling application to a substrate. Hot-melt adhesives are required to have the following properties: (1) a sufficiently low viscosity when heated and melted, ensuring good coatability; (2) a long enough time to ensure bonding with the other adherend after application to the adherend; (3) high initial adhesive strength measured shortly after bonding; and (4) good final physical properties of the cured product. However, it is difficult to achieve such physical properties with the graft copolymers disclosed in Patent Documents 1 to 5. In particular, it was difficult to obtain a cured product with high initial adhesive strength and high resilience.

[0011] In view of the above situation, the present invention aims to provide a reactive silicon group-containing graft copolymer having a (meth)acrylate polymer block and a polyoxyalkylene polymer block, which has high initial adhesive strength after bonding and good resilience of the cured product.

Means for Solving the Problems

[0012] As a result of intensive studies to solve the above problems, the present inventors have found that in a graft copolymer having a (meth)acrylate polymer block and a polyoxyalkylene polymer block having a reactive silicon group, by bonding each block in a specific order and setting the weight ratio of each block, the content of (meth)acrylate alkyl ester having 4 or more carbon atoms in the alkyl group, and the sulfur atom concentration derived from the chain transfer agent within specific ranges, the above problems can be solved, and the present invention has been completed.

[0013] That is, the present invention provides a compound represented by the general formula (1): -SiR 1 3-a X a (1) (In the formula, 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 (meth)acrylate polymer block (A) having a reactive silicon group represented by, and a polyoxyalkylene polymer block (B) having a number average molecular weight of 10,000 to 20,000 and a molecular weight distribution (Mw / Mn) of 1.0 to 1.5, which are graft copolymers bonded in the order of A-B-A, In the graft copolymer, the proportion of the polymer block (A) is 35 to 70% by weight, and the proportion of the polymer block (B) is 30 to 65% by weight. The polymer block (A) contains a structural unit derived from a (meth)acrylate (a1) and a structural unit derived from a chain transfer agent (a2) having a mercapto group. The content of the (meth)acrylate alkyl ester having 4 or more carbon atoms in the alkyl group is 2% by weight or more and 12% by weight or less in the graft copolymer. The reactive silicon group equivalent derived from the (meth)acrylate (a1) is 0.15 mmol / g or less. Regarding a graft copolymer, the sulfur atom concentration derived from the chain transfer agent (a) is 4,000 to 10,000 ppm in the graft copolymer. [Effect of the Invention]

[0014] According to the present invention, there is provided a reactive silicon group-containing graft copolymer having a (meth)acrylate polymer block and a polyoxyalkylene polymer block, which has high initial adhesive strength after lamination and good resilience of the cured product. 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 of a hot-melt adhesive. [Brief Description of the Drawings]

[0015] [Figure 1] Conceptual diagram of the H-type structure that can be included in the graft copolymer according to the present disclosure [Embodiments for Carrying Out the Invention]

[0016] Embodiments of the present invention will be specifically described below, but the present invention is not limited to these embodiments.

[0017] The graft copolymer according to this embodiment is formed by bonding a (meth)acrylate polymer block (A) and a polyoxyalkylene polymer block (B). The graft copolymer has a reactive silicon group, and the reactive silicon group is bonded to the (meth)acrylate polymer block (A). In the present application, “(meth)acryl” represents “acryl and / or methacryl”.

[0018] <Reactive silicon group> The (meth)acrylate polymer block (A) has a reactive silicon group represented by the following general formula (1) at the molecular chain end and / or side chain (non-terminal site). -SiR 1 3-a X a (1) (In the formula, 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.)

[0019] 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. Specific examples of R 1 include, for example, a methyl group, an ethyl group, a chloromethyl group, a methoxymethyl group, and a N,N-diethylaminomethyl group. Preferably, they are a methyl group, an ethyl group, a chloromethyl group, and a methoxymethyl group, and more preferably, they are a methyl group and a methoxymethyl group.

[0020] Examples of X include hydroxyl groups, halogens, alkoxy groups, acyloxy groups, ketoximate groups, amino groups, amide groups, acid amide groups, aminooxy groups, mercapto groups, and alkenyloxy groups. Among these, alkoxy groups are more preferred due to their mild hydrolysis and ease of handling, and methoxy and ethoxy groups are particularly preferred.

[0021] Examples of the reactive silicon group include, but are not limited to, trimethoxysilyl group, triethoxysilyl group, tris(2-propenyloxy)silyl group, triacetoxysilyl group, dimethoxymethylsilyl group, diethoxymethylsilyl group, dimethoxyethylsilyl group, (chloromethyl)dimethoxysilyl group, (chloromethyl)diethoxysilyl group, (methoxymethyl)dimethoxysilyl group, (methoxymethyl)diethoxysilyl group, (N,N-diethylaminomethyl)dimethoxysilyl group, and (N,N-diethylaminomethyl)diethoxysilyl group. Among these, the 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 yield cured products with good mechanical properties. The trimethoxysilyl group and triethoxysilyl group are more preferred because they yield cured products with high fracture strength, and the trimethoxysilyl group is even more preferred.

[0022] The reactive silicon group equivalent of the graft copolymer according to this embodiment is preferably 0.1 to 0.40 mmol / g, for example, 0.10 to 0.30 mmol / g, 0.15 to 0.30 mmol / g, 0.20 to 0.30 mmol / g, etc., from the viewpoint of achieving the effects of the invention described above.

[0023] <(meth)acrylic acid ester polymer block (A)> The (meth)acrylic acid ester polymer block (A) is a polymer block comprising at least a constituent unit derived from (meth)acrylic acid ester (a1) and a constituent unit derived from a chain transfer agent (a2) having a mercapto group.

[0024] <(meth)acrylic acid ester (a1)> (Meth)acrylic acid esters (a1) are broadly classified into (meth)acrylic acid esters (a1-1) that do not have a reactive silicon group and (meth)acrylic acid esters (a1-2) that do have a reactive silicon group. The (meth)acrylate ester (a1-1) that does not have a reactive silicon group is not particularly limited, but examples 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, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2- Examples include hydroxypropyl, 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-perfluorobutyl ethyl (meth)acrylate, trifluoromethyl (meth)acrylate, perfluoroethyl (meth)acrylate, bis(trifluoromethyl)methyl (meth)acrylate, 2-trifluoromethyl-2-perfluoroethyl ethyl (meth)acrylate, 2-perfluorohexyl ethyl (meth)acrylate, 2-perfluorodecyl ethyl (meth)acrylate, 2-perfluorohexadecyl ethyl (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)acrylate ester (a1-1) that does not have a reactive silicon group, alkyl (meth)acrylate is preferred.

[0025] The content of (meth)acrylic acid ester (a1-1) without reactive silicon groups is preferably 30% by weight or more, more preferably 40% by weight or more, and even more preferably 50% by weight or more, of the total amount of constituent units forming the (meth)acrylic acid ester polymer block (A), from the viewpoint of achieving both flexibility and high rigidity. The upper limit is preferably 90% by weight or less, and more preferably 80% by weight or less.

[0026] Since a hard polymer block (A) can be formed and a highly strong cured product can be obtained, it is preferable that the (meth)acrylic acid ester (a1-1) that does not have a reactive silicon group contains an alkyl methacrylate ester with four or fewer C12 atoms in the alkyl group. The content of the monomer in the graft copolymer according to this embodiment is preferably 10% by weight or more, more preferably 20% by weight or more, and particularly preferably 30% by weight or more.

[0027] However, from the viewpoint of lowering the viscosity of the graft copolymer when heated and melted, and ensuring a longer time for bonding after application of the graft copolymer, the monomer content in the graft copolymer according to this embodiment is preferably 45% by weight or less, and more preferably 40% by weight or less.

[0028] The content of alkyl (meth)acrylate esters with 4 or more carbon atoms in the alkyl group, which correspond to (meth)acrylate esters (a1-1) that do not have reactive silicon groups, is set to a range of 2% by weight or more and 12% by weight or less in the graft copolymer. By reducing the amount of alkyl (meth)acrylate esters having long-chain alkyl groups used, the resilience of the cured product can be improved. The upper limit is preferably 9% by weight or less, and more preferably 7% by weight or less. If it exceeds 12% by weight, the strength of the cured product tends to decrease.

[0029] The (meth)acrylic acid ester (a1-2) having a reactive silicon group is any monomer and may not be used, but its use is preferred. The reactive silicon group possessed by (a1-2) is the reactive silicon group represented by the general formula (1) described above. By using monomer (a1-2), a reactive silicon group can be introduced into the side chain (non-terminal portion) of the (meth)acrylic acid ester polymer block (A).

[0030] The (meth)acrylic acid esters (a1-2) having a reactive silicon group are not particularly limited, but examples include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyldimethoxymethylsilane, (meth)acryloxymethyltrimethoxysilane, and (meth)acryloxymethyldimethoxymethylsilane. These compounds may be used individually or in combination of two or more.

[0031] When using (meth)acrylic acid esters (a1-2) having reactive silicon groups, the content of (a1-2) is preferably 1% by weight or more and 10% by weight or less of the total amount of constituent units forming the (meth)acrylic acid ester polymer block (A). For example, the upper limit may be 9% by weight or less, 7% by weight or less, or 5% by weight or less, and the lower limit may be 1.5% by weight or more, 2% by weight or more, or 2.5% by weight or more.

[0032] <Chain transfer agent having a mercapto group (a2)> By using a chain transfer agent (a2) containing a mercapto group, the molecular weight of the (meth)acrylic acid ester polymer block (A) can be controlled. Furthermore, the molecular weight distribution of the graft copolymer can be narrowed, and gelation during the synthesis of the graft copolymer can be suppressed. Additionally, it becomes possible to preferentially synthesize polymer molecules in which one polyoxyalkylene polymer block (B) is introduced into each graft copolymer molecule.

[0033] The chain transfer agent (a2) having a mercapto group may not have a reactive silicon group, but it is preferable that it has a reactive silicon group. The reactive silicon group is the reactive silicon group represented by the general formula (1) described above. By having a reactive silicon group in the chain transfer agent (a2) having a mercapto group, a reactive silicon group can be introduced to the molecular chain ends of the (meth)acrylic acid ester polymer block (A).

[0034] The chain transfer agent (a2) having a mercapto group is not particularly limited, but examples include 3-mercaptopropyldimethoxymethylsilane, 3-mercaptopropyltrimethoxysilane, (mercaptomethyl)dimethoxymethylsilane, (mercaptomethyl)trimethoxysilane, n-dodecylmercaptan, tert-dodecylmercaptan, laurylmercaptan, and the like.

[0035] The content of the chain transfer agent (a2) having a mercapto group is preferably 1% by weight or more and 10% by weight or less of the total amount of constituent units forming the (meth)acrylic acid ester polymer block (A), more preferably 2% by weight or more and 8% by weight or less, and even more preferably 3% by weight or more and 6% by weight or less.

[0036] Furthermore, the content of the chain transfer agent (a2) having a mercapto group is preferably 0.1 mol% to 10 mol%, more preferably 0.4 mol% to 9 mol%, even more preferably 0.5 mol% to 7 mol%, and particularly preferably 0.6 mol% to 6 mol% of the total amount of constituent units forming the (meth)acrylic acid ester polymer block (A).

[0037] The ratio of the polyoxyalkylene polymer block (B) to the chain transfer agent (a2) having mercapto groups is such that the initial adhesive strength is high. Therefore, the molar ratio of polyoxyalkylene polymer block (B) to chain transfer agent (a2) is preferably 0.03 or higher, more preferably 0.06 or higher, even more preferably 0.08 or higher, and particularly preferably 0.10 or higher. There is no particular upper limit to the molar ratio, but since the final strength of the cured product is high, it is preferably 0.50 or lower, more preferably 0.30 or lower, and even more preferably 0.25 or lower.

[0038] The graft copolymer or (meth)acrylic acid ester polymer block (A) according to this embodiment has substituents (described later as -SR) derived from a chain transfer agent (a2) having a mercapto group. 8 It may contain sulfur atoms because it has a structure represented by .

[0039] In the graft copolymer according to this embodiment, the sulfur atom concentration derived from the chain transfer agent (a2) is set to 4,000 ppm or more and 10,000 ppm or less in the graft copolymer. This sulfur atom concentration is a value relative to the solid content of the graft copolymer, and the solvent is excluded from its calculation.

[0040] The aforementioned sulfur atom concentration reflects the proportion of chain transfer agent used in the graft polymer. If the sulfur atom concentration is less than 4,000 ppm, the proportion of chain transfer agent used is low, and block (A) tends to have a relatively high molecular weight. As a result, the viscosity of the graft copolymer when heated and melted becomes high, or it becomes too hard, making it difficult to ensure a long time for bonding after application of the graft copolymer. In addition, the strength and elongation of the cured product may be insufficient. If the sulfur atom concentration exceeds 10,000 ppm, the proportion of chain transfer agent used is high, and block (A) tends to have a relatively low molecular weight. As a result, the initial adhesive strength may be insufficient, or the strength of the cured product may decrease.

[0041] The lower limit of the sulfur atom concentration may be, for example, 4,100 ppm or more and 4,200 ppm or more, and the upper limit may be, for example, 8,000 ppm or less and 6,000 ppm or less.

[0042] 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. Alternatively, the sulfur atom concentration may be a theoretical value calculated from the total amount of components used in the production of the graft copolymer and the amount of the chain transfer agent (a2) having a mercapto group.

[0043] (Meth)acrylic acid ester polymer block (A) may have a reactive silicon group if it satisfies one or both of the following two conditions. Condition 1: (meth)acrylic acid ester (a1) includes a (meth)acrylic acid ester having a reactive silicon group. Condition 2: The chain transfer agent (a2) having a mercapto group further has a reactive silicon group.

[0044] To obtain a cured product with high strength, it is preferable to introduce reactive silicon groups by both conditions 1 and 2. Specifically, the reactive silicon group equivalent derived from (a1) may be, for example, 0.01 mmol / g or more, 0.02 mmol / g or more, or 0.05 mmol / g or more, from the viewpoint of the resilience of the cured product. Also, the reactive silicon group equivalent derived from (a1) may be, for example, 0.15 mmol / g or less, 0.14 mmol / g or less, or 0.12 mmol / g or less, from the viewpoint of the elongation of the cured product. On the other hand, the reactive silicon group equivalent derived from (a2) is preferably 0.05 mmol / g or more, and 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.

[0045] The components forming the (meth)acrylic acid ester polymer block (A) may or may not contain other monomers (a3) ​​that do not fall under either (a1) or (a2) as described above.

[0046] Other monomers (a3) ​​include, for example, styrene 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 its derivatives such as maleic acid, maleic anhydride, maleic acid monoalkyl esters, and maleic acid dialkyl esters; fumaric acid and its derivatives such as fumaric acid monoalkyl esters and fumarate dialkyl esters; maleimide, methyl maleimide, ethyl maleimide, propyl maleimide, and butyl maleimide. Examples include maleimide monomers such as hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, and cyclohexylmaleimide; vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate; olefin monomers such as ethylene and propylene; conjugated diene monomers such as butadiene and isoprene; (meth)acrylamide; (meth)acrylonitrile; and vinyl monomers such as vinyl chloride, vinylidene chloride, allyl chloride, allyl alcohol, ethyl vinyl ether, and butyl vinyl ether. Other monomers may be used individually or in combination of two or more.

[0047] <Polyoxyalkylene polymer block (B)> The polyoxyalkylene polymer constituting the polyoxyalkylene polymer block (B) is not particularly limited and includes, for example, polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymer, and polyoxypropylene-polyoxybutylene copolymer. Among these, polyoxypropylene is preferred.

[0048] The main chain skeleton of the polyoxyalkylene polymer may be linear or branched, but it is preferable that it be linear.

[0049] The number-average molecular weight of the polyoxyalkylene polymer block (B) is preferably 10,000 to 20,000. Within this range, the initial adhesive strength is good and the resilience of the cured product obtained from the graft copolymer can be improved. The lower limit of the number-average molecular weight may be, for example, 11,000 or more, or 12,000 or more. The upper limit may be 18,000 or less, or 16,000 or less, from the viewpoint of initial adhesive strength.

[0050] The molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of the polyoxyalkylene polymer block (B) is not particularly limited, but is preferably narrow, specifically less than 2.0, and may be, for example, 1.6 or less, 1.4 or less, or 1.2 or less. The narrower the molecular weight distribution, the lower the viscosity tends to be when heated and melted. In addition, the initial adhesive strength tends to be achieved more easily in a short time after bonding.

[0051] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the polyoxyalkylene polymer block (B) are values ​​measured in polystyrene equivalent by gel permeation chromatography (GPC) of the polyfunctional macromonomer (b-1), which will be described later. The detailed measurement method is described in the examples.

[0052] The polyoxyalkylene polymer block (B) can be introduced into the graft copolymer by using a polyoxyalkylene polymer (b-1) having an average of more than one (meth)acryloyl group in its molecule. Polymer (b-1) is a polymer itself, but it is one of the components that make up the graft copolymer according to this embodiment. Because polymer (b-1) has (meth)acryloyl groups, it can copolymerize with (meth)acrylic acid ester (a1). Moreover, since polymer (b-1) has more than one (meth)acryloyl group in one molecule, it can function as a so-called polyfunctional macromonomer. Hereinafter, polymer (b-1) will also be referred to as polyfunctional macromonomer (b-1).

[0053] The (meth)acryloyl group of the polyfunctional macromonomer (b-1) is not particularly limited, but can be represented by the following general formula (4) or (5). CH2=C(R 7 )-C(=O)-OR-NH-C(=O)-OB (4) CH2=C(R 7 )-C(=O)-OB (5) In each formula, R 7 represents a hydrogen or methyl group. B represents a polyoxyalkylene polymer block (B). R represents a divalent 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.

[0054] The polyfunctional macromonomer (b-1) has an average of more than one (meth)acryloyl group per molecule. The average number of (meth)acryloyl groups per molecule of polyfunctional macromonomer (b-1) 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 polyfunctional macromonomer (b-1) may have only acryloyl groups, only methacryloyl groups, or both acryloyl and methacryloyl groups as (meth)acryloyl groups.

[0055] The polyfunctional macromonomer (b-1) may have (meth)acryloyl groups at either the molecular chain ends or side chains, or both, of the polyoxyalkylene polymer. From the viewpoint of excellent mechanical properties, it is preferable that the groups be at the molecular chain ends. In particular, it is especially preferable that the polyfunctional macromonomer (b-1) has a linear main chain skeleton and has (meth)acryloyl groups at both ends of its molecular chain.

[0056] There are no particular limitations on the method for synthesizing the polyfunctional macromonomer (b-1), but one example is to prepare a polyoxyalkylene polymer having one or more hydroxyl groups in the molecule (preferably a linear polyoxyalkylene polymer having hydroxyl groups at both ends), and then introduce (meth)acryloyl groups using these hydroxyl groups.

[0057] As an example of a method for synthesizing polyfunctional macromonomers (b-1), a compound having an isocyanate group and a (meth)acryloyl group can be reacted with a polyoxyalkylene polymer having a hydroxyl group to form a urethane bond and introduce a (meth)acryloyl group. Specific examples of compounds having the isocyanate group and (meth)acryloyl group include, for example, isocyanate ethyl (meth)acrylate, isocyanate propyl (meth)acrylate, isocyanate butyl (meth)acrylate, and isocyanate hexyl (meth)acrylate.

[0058] Another example of a method for synthesizing polyfunctional macromonomers (b-1) is to introduce isocyanate groups into a polyoxyalkylene polymer having hydroxyl groups by reacting it with a diisocyanate compound, and then introduce (meth)acryloyl groups by reacting it with a compound having both hydroxyl groups and (meth)acryloyl groups. Specific examples of the diisocyanate compounds include, for example, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and 4,4'-diphenylmethane diisocyanate. Specific examples of compounds having the hydroxyl group and (meth)acryloyl group include, for example, hydroxybutyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate.

[0059] As yet another example of a method for synthesizing polyfunctional macromonomers (b-1), a carboxyl group can be introduced into a polyoxyalkylene polymer having a hydroxyl group by reacting it with an acid anhydride, and then a (meth)acryloyl group can be introduced by reacting it with a compound having an epoxy group and a (meth)acryloyl group. Specific examples of the aforementioned acid anhydrides include, for example, succinic anhydride, maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhymic anhydride, trimellitic anhydride, methylnadic anhydride, and dodecyl succinic anhydride. Specific examples of compounds having the epoxy group and the (meth)acryloyl group include, for example, glycidyl (meth)acrylate.

[0060] Another example of a method for synthesizing polyfunctional macromonomers (b-1) involves dehydration condensation of methacrylic acid and acrylic acid with a polyoxyalkylene polymer containing hydroxyl groups. Furthermore, to carry out the reaction under milder conditions, a method is used in which methacrylate chloride, methacrylate bromide, methacrylate iodide, acrylate chloride, acrylate bromide, and acrylate iodide are reacted with a polyoxyalkylene polymer containing hydroxyl groups.

[0061] In the graft copolymer according to this embodiment, the proportion of block (A) to the total of the (meth)acrylic acid ester polymer block (A) and the polyoxyalkylene polymer block (B) is 35 to 70% by weight, and the proportion of block (B) is 30 to 65% by weight. Within this range, a good balance is achieved between the physical properties achieved by block (A) and the physical properties achieved by block (B), and the effects of the invention described above can be achieved. If the proportion of block (B) is less than 30% by weight, the viscosity of the graft copolymer when heated and melted becomes high, or the elongation of the cured product obtained from the graft copolymer becomes low. On the other hand, if the proportion of block (B) exceeds 65% by weight, the initial adhesive strength and the final strength of the cured product may be low. The proportion of block (A) is preferably 40-65% by weight, and the proportion of block (B) is preferably 35-60% by weight, with the former being more preferably 45-60% by weight and the latter 40-55% by weight.

[0062] Furthermore, from the viewpoint of the invention described above, the content of the polyoxyalkylene polymer block (B) should be 0.05 mol% to 6.0 mol% of the total amount of constituent units forming the graft copolymer. For example, it is preferable that it be 0.1 mol% to 2.3 mol% or 0.2 mol% to 1.5 mol%.

[0063] The average number of polyoxyalkylene 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 using the following formula. Formula: Number average molecular weight of graft copolymer (g / mol) / (Weight of graft copolymer (g) / (Number of moles of polymer block (B)))

[0064] <Block combination format> The graft copolymer according to this embodiment has a (meth)acrylic acid ester polymer block (A) and a polyoxyalkylene polymer block (B) bonded in the order ABA. However, the graft copolymer is not limited to a triblock, and may also include a structure in which block (B) and / or block (A) are further bonded to the triblock.

[0065] The graft copolymer according to this embodiment may be prepared by free radical polymerization. When prepared by free radical polymerization, some molecules in the graft copolymer may include polymer components in which block (A) and block (B) are not bonded to each other. In this application, "graft copolymer" is defined as including such unbonded polymer components. The ratio of graft copolymers in which block (A) and block (B) are bonded to unbonded polymer components can be easily determined by known means, such as GPC analysis.

[0066] In the graft copolymer according to this embodiment, it is preferable that block (A) and block (B) are linked via ester bonds derived from the (meth)acryloyl group in the polyfunctional macromonomer (b-1) (i.e., ester bonds in the general formula (4) or (5)).

[0067] The form of the combination between block (A) and block (B) is not particularly limited, but can be expressed by the following general formula (2) or (3). AC(=O)-OR-NH-C(=O)-OB (2) AC(=O)-OB (3) In each formula, A represents polymer block (A), and B represents polymer block (B). R represents a divalent 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.

[0068] It is preferable that block (A) is composed of a hard polymer and block (B) is composed of a soft polymer, as this makes it easier to obtain a cured product with high strength and high elongation. 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.

[0069] When block (A) is composed of a rigid polymer, as described above, it is preferable that (meth)acrylic acid ester (a1-1) contains an alkyl methacrylate ester with four or fewer C1 atoms in the alkyl group.

[0070] Since block (A) is a molecular chain formed by reacting with a chain transfer agent (a2) having a mercapto group, the substituent derived from (a2) is -SR at the end of block (A). 8 It may have a structure represented by the above formula. In the above formula, S represents a sulfur atom, and R 8 R represents a hydrocarbon group which may have a reactive silicon group. Examples of the hydrocarbon group include alkyl groups, aryl groups, or aralkyl groups having 1 to 20 carbon atoms. The reactive silicon group is the reactive silicon group represented by the general formula (1) described above. 8 Specific examples include, for instance, reactive silicon-containing methyl groups, reactive silicon-containing propyl groups, n-dodecyl groups, tert-dodecyl groups, and lauryl groups.

[0071] The graft copolymer according to this embodiment may have a linear structure in which the ends of block (A) and the ends of block (B) are connected, but it is preferable that it includes an H-type structure. Figure 1 shows a conceptual diagram of the H-shaped structure. In this structure, the two vertical bars represent block (A), and the one horizontal bar represents block (B). Both ends of block (B) are bonded to the non-terminal sites of block (A). At one end of each of the two blocks (A), there is a substituent derived from a chain transfer agent having a mercapto group and a reactive silicon group, namely -SR. 8 -SiR 1 3-a X a It is bonded to the non-terminal portion of block (A).1 3-a X a These are randomly bonded, which originates from (meth)acrylic acid esters (a1-2) having reactive silicon groups.

[0072] The H-type structure can be formed by random polymerization of a polyfunctional macromonomer (b-1), which has (meth)acryloyl groups at both ends of a polyoxyalkylene polymer molecular chain, with a (meth)acrylic acid ester (a1) and a chain transfer agent (a2) having a mercapto group.

[0073] <Molecular weight of graft copolymer> The number-average molecular weight of the graft copolymer according to this embodiment is not particularly limited, but it is preferably 2,000 to 10,000 in polystyrene equivalent molecular weight as measured by GPC. The lower limit of the number-average molecular weight of the graft copolymer may be, for example, 2,500 or more, or 3,000 or more, and the upper limit is preferably 6,000 or less, as this yields a low-viscosity graft copolymer. Furthermore, the number-average molecular weight is preferably 5,000 or less, or 4,800 or less, as this provides excellent initial adhesive strength.

[0074] The weight-average molecular weight of the graft copolymer is not particularly limited, but is preferably 10,000 to 50,000 in polystyrene equivalent molecular weight as measured by GPC, more preferably 3,000 to 70,000, and particularly preferably 15,000 to 45,000. In particular, a weight-average molecular weight of 40,000 or less is preferred because it yields a cured product with low viscosity and high strength.

[0075] 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 low viscosity, it is preferably 5.0 to 9.5, for example, 6.0 to 9.5 or 7.0 to 9.0.

[0076] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the graft copolymer are measured in polystyrene equivalents by gel permeation chromatography (GPC). Detailed measurement methods are described in the examples. As mentioned above, graft copolymers may contain polymer components in which block (A) and block (B) are not bonded to each other. However, the number-average molecular weight, weight-average molecular weight, and molecular weight distribution of the graft copolymers are values ​​measured for graft copolymers that include such polymer components.

[0077] <Method for producing graft copolymer> The graft copolymer according to this embodiment can be produced by polymerizing a (meth)acrylic acid ester (a1), a chain transfer agent having a mercapto group (a2), any other monomer (a3), and a polyfunctional macromonomer (b-1). The polymerization method is not particularly limited, but may be a general free radical polymerization. According to this embodiment, despite being free radical polymerization, polymerization can be controlled, a graft copolymer can be produced, and its molecular weight distribution can be made relatively narrow.

[0078] Examples of polymerization initiators usable in the aforementioned 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-carbonitride). Diacyl peroxides such as benzoyl peroxide, isobutyryl peroxide, isononanoyl peroxide, decanoyl peroxide, lauroyl peroxide, parachlorobenzoyl peroxide, and di(3,5,5-trimethylhexanoyl) peroxide; diisopropyl peroxide, di-sec-butyl peroxide, di-2-ethylhexyl peroxide, di-1-methylheptyl peroxide, and di-3-methoxybutyl peroxide; Examples include peroxydicarbonates such as di-dicarbonate and dicyclohexyl per-dicarbonate; peroxyesters 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; dialkyl peroxides such as di-tert-butyl peroxide, diquyl peroxide, tert-butylquyl 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 individually or in combination of two or more.

[0079] Examples of solvents usable 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 poorly soluble in alcohol-based solvents, it is preferable to use non-alcohol-based solvents. In particular, it is preferable to use carboxylic acid ester-based solvents. Aromatic solvents are preferred due to their high solubility.

[0080] As described above, graft copolymers acquire reactive silicon groups by using (meth)acrylic acid esters having reactive silicon groups, or by using chain transfer agents that have reactive silicon groups in addition to mercapto groups. Both methods may be used in combination. By using (meth)acrylic acid esters having reactive silicon groups, reactive silicon groups can be randomly introduced into the side chains of (meth)acrylic acid ester polymer block (A). Alternatively, by using chain transfer agents that have reactive silicon groups in addition to mercapto groups, reactive silicon groups can be introduced into the terminals of (meth)acrylic acid ester polymer block (A).

[0081] However, the following methods can also be used in combination to further introduce reactive silicon groups into the graft copolymer. (i) A method of copolymerizing a monomer having a reactive functional group (V group) with a (meth)acrylic acid ester (a1) or the like, and then reacting the resulting copolymer with a compound having a functional group that reacts with the V group and a reactive silicon group. Specifically, examples include a method of copolymerizing 2-hydroxyethyl acrylate and then reacting it with an isocyanate silane compound having a reactive silicon group, or a method of copolymerizing glycidyl acrylate and then reacting it with an aminosilane compound having a reactive silicon group. (ii) A method for introducing reactive silicon groups by modifying the terminal functional groups of a (meth)acrylic acid ester copolymer synthesized by living radical polymerization. (meth)acrylic acid ester copolymers obtained by living radical polymerization readily have functional groups introduced at the polymer ends, and reactive silicon groups can be introduced at the polymer ends by modifying them.

[0082] Compounds having a functional group that reacts with the V group and a reactive silicon group used in method (i) include, for example, isocyanate silane compounds such as 3-isocyanate propyl dimethoxymethylsilane, 3-isocyanate propyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, isocyanate methyl dimethoxymethylsilane, isocyanate methyl trimethoxysilane, and isocyanate methyl triethoxysilane; 3-glycidoxypropyl dimethoxymethylsilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl triethoxysilane, and glycidoxymethyl Examples include epoxysilane compounds such as dimethoxymethylsilane, glycidoxymethyltrimethoxysilane, and glycidoxymethyltriethoxysilane; and aminosilane compounds such as 3-aminopropyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, aminomethyldimethoxymethylsilane, aminomethyltrimethoxysilane, aminomethyltriethoxysilane, N-cyclohexylaminomethyldimethoxymethylsilane, N-cyclohexylaminomethyltrimethoxysilane, and N-cyclohexylaminomethyltriethoxysilane.

[0083] Method (ii) can utilize any modification reaction, but examples include a method using a compound having a reactive group and a reactive silicon group that can react with terminal functional groups obtained by living radical polymerization, or a method in which a double bond is introduced to the polymer terminal using a compound having a reactive group and a double bond that can react with terminal functional groups, and then a reactive silicon group is introduced using a hydrosilylation reaction or the like.

[0084] <<Curable composition>> The graft copolymer according to this embodiment can constitute 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.

[0085] <Silanol condensation catalyst> Examples of silanol condensation catalysts include organotin compounds, metal carboxylate salts, amine compounds, carboxylic acids, and alkoxy metals.

[0086] Specific examples of organotin compounds include dibutyltin dilaurate, dibutyltin dioctanoate, dibutyltin bis(butylmaleate), dibutyltin diacetate, dibutyltin oxide, dibutyltin bis(acetylacetonate), dioctyltin bis(acetylacetonate), dioctyltin dilaurate, dioctyltin distearate, dioctyltin diacetate, dioctyltin oxide, reaction products of dibutyltin oxide with silicate compounds, reaction products of dioctyltin oxide with silicate compounds, and reaction products of dibutyltin oxide with phthalate esters.

[0087] Specific examples of metal carboxylate salts include tin carboxylate, bismuth carboxylate, titanium carboxylate, zirconium carboxylate, and iron carboxylate. Various metals can be combined with the following carboxylic acids to form metal carboxylate salts.

[0088] Specific examples of amine compounds 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 butyl biguanide, 1-o-tolylbiguanide, and 1-phenylbiguanide; amino group-containing silane coupling agents; and ketimine compounds.

[0089] 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.

[0090] Specific examples of alkoxy metals include titanium compounds such as tetrabutyl titanate titanium tetrakis (acetylacetonate) and diisopropoxy titanium bis (ethylacetoacetate), aluminum compounds such as aluminum tris (acetylacetonate) and diisopropoxyaluminum ethylacetoacetate, and zirconium compounds such as zirconium tetrakis (acetylacetonate).

[0091] When using a silanol condensation catalyst, 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, per 100 parts by weight of the graft copolymer according to this embodiment, from the viewpoint of promoting the condensation reaction of reactive silicon groups.

[0092] <<Other additives>> In addition to the graft copolymer and silanol condensation catalyst according to this embodiment, the curable composition according to this embodiment may also contain additives such as plasticizers, fillers, adhesion promoters, dehydrators, rheology control agents, antioxidants, light stabilizers, ultraviolet absorbers, and other resins.

[0093] 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 modifiers, silicates, curability modifiers, radical inhibitors, metal deactivators, ozone degradation inhibitors, phosphorus-based peroxide decomposers, lubricants, pigments, antifungal agents, flame retardants, and foaming agents.

[0094] <Plasticizer> Plasticizers can be added to the curable composition. The addition of plasticizers can reduce the viscosity of the curable composition, making it easier to handle.

[0095] The plasticizer is not particularly limited, but examples include phthalate compounds such as dibutyl phthalate, diisononyl phthalate (DINP), diheptyl phthalate, di(2-ethylhexyl) phthalate, diisodecyl phthalate (DIDP), and butyl benzyl phthalate; terephthalate compounds such as bis(2-ethylhexyl)-1,4-benzenedicarboxylate; non-phthalate compounds such as 1,2-cyclohexanedicarboxylic acid diisononyl ester; and fats such as dioctyl adipic acid, dioctyl sebacate, dibutyl sebacate, diisodecyl succinate, and tributyl acetylcitrate. Examples include polyvalent carboxylic acid ester compounds; unsaturated fatty acid ester compounds such as butyl oleate and methyl acetylricinoleate; phosphate ester compounds; trimellitic acid ester compounds; chlorinated paraffin; hydrocarbon oils such as alkyldiphenyl and partially hydrogenated terphenyl; process oils; epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, bis(2-ethylhexyl)-4,5-epoxycyclohexane-1,2-dicarbonoxylate (E-PS), epoxyoctyl stearate, epoxybutyl stearate and benzyl epoxystearate; and alkyl sulfonic acid esters.

[0096] Polymeric plasticizers can also be used as plasticizers. Specific examples of polymeric plasticizers include vinyl polymers; polyester plasticizers; polyether polyols such as polyethylene glycol and polypropylene glycol with a number average molecular weight of 500 or more, and polyether plasticizers such as derivatives obtained by converting the hydroxyl groups of these polyether polyols to ester groups, ether groups, etc.; polystyrenes; polybutadiene, polybutene, polyisobutylene, butadiene-acrylonitrile, polychloroprene, etc. Among these, polymeric plasticizers are preferred, polyether-based plasticizers are more preferred, and polypropylene glycol is particularly preferred. You may use only one type of plasticizer, or you may use two or more types in combination.

[0097] The amount of plasticizer 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 graft copolymer.

[0098] <Filler> Fillers can be added to the curable composition. The strength of the cured product can be improved by adding fillers.

[0099] Examples of fillers include heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, diatomaceous earth, clay, talc, titanium dioxide, fumed silica, settling silica, crystalline silica, fused silica, anhydrous silicic acid, hydrated silicic acid, alumina, carbon black, ferric oxide, aluminum powder, zinc oxide, activated zinc oxide, PVC powder, PMMA powder, glass fibers, and filaments. Organic balloons and inorganic balloons may be added to reduce the weight (low specific gravity) of the composition. Only one type of filler may be used, or two or more types may be used in combination.

[0100] The amount of filler added is preferably 1 to 300 parts by weight, and more preferably 10 to 250 parts by weight, per 100 parts by weight of graft copolymer.

[0101] <Adhesion-enhancing agent> Adhesion-imparting agents may be added to the curable composition. As an adhesion-improving agent, a silane coupling agent or a reaction product of a silane coupling agent can be added.

[0102] Specific examples of silane coupling agents 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; as well as γ-isocyanatetopropyltrimethoxysilane, γ-isocyanatetopropyltriethoxysilane, and γ-iso Examples include isocyanate group-containing silanes such as cyanate-propylmethyldimethoxysilane, α-isocyanate-methyltrimethoxysilane, and α-isocyanate-methyldimethoxymethylsilane; 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 mixture of two or more types.

[0103] The amount of adhesion promoter added is preferably 0.1 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight, per 100 parts by weight of graft copolymer.

[0104] <Dehydrating agent> A dehydrating agent may be added to the curable composition. Here, the dehydrating agent is preferably a compound that can react with water, more preferably a silicon compound that can react with water (excluding compounds that are adhesion promoters), and particularly preferably a trialkoxysilane compound.

[0105] Specific examples of the dehydrating agent are not limited to vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and other vinyl group-containing silanes. The dehydrating agent may be used alone or in combination of two or more types.

[0106] The amount of dehydrating agent 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, per 100 parts by weight of graft copolymer.

[0107] <Rheology control agent> Rheology control agents may be added to the curable composition as needed to prevent sagging and improve workability.

[0108] The rheology control agents are not particularly limited, but examples 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.

[0109] The amount of rheology control agent added is preferably 0.1 to 20 parts by weight per 100 parts by weight of graft copolymer.

[0110] <Antioxidant> Antioxidants (anti-aging agents) can be used in the curable composition. Using antioxidants 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 Japanese Patent Publication No. 4-283259 and Japanese Patent Publication No. 9-194731. The amount of antioxidant added is preferably 0.1 to 10 parts by weight, and more preferably 0.2 to 5 parts by weight, per 100 parts by weight of graft copolymer.

[0111] <Light stabilizer> Light stabilizers can be used in the curable composition. Using light stabilizers can prevent photo-oxidative degradation of the cured product. Examples of light stabilizers include benzotriazole-based, hindered amine-based, and benzoate-based compounds, but hindered amine-based compounds are particularly preferred. The amount of light stabilizer added is preferably 0.1 to 10 parts by weight, and more preferably 0.2 to 5 parts by weight, per 100 parts by weight of graft copolymer.

[0112] <UV absorber> UV absorbers can be used in the curable composition. Using UV absorbers can improve the surface weather resistance of the cured product. Examples of UV absorbers include benzophenone-based, benzotriazole-based, salicylate-based, substituted tolyl-based, and metal chelate compounds, but benzotriazole-based compounds are particularly preferred, and examples include commercially available products such as Tinuvin P, Tinuvin 213, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 329, and Tinuvin 571 (all manufactured by BASF). The amount of UV absorber added is preferably 0.1 to 10 parts by weight, and more preferably 0.2 to 5 parts by weight, per 100 parts by weight of graft copolymer.

[0113] A curable composition according to one embodiment of the present invention can be prepared as a one-component type that hardens upon application by moisture in the air after the composition has been pre-mixed and sealed for storage. In this case, it is preferable to dehydrate and dry any components containing moisture before use, or to dehydrate them by reducing pressure during mixing.

[0114] Furthermore, a curable composition according to one embodiment of the present invention can also be prepared as a two-component type, comprising a main component containing a graft copolymer and a curing agent containing components such as a silanol condensation catalyst, filler, plasticizer, and water, and the main component and curing agent are mixed before use.

[0115] There are no particular limitations on the method for preparing the curable composition according to one embodiment of the present invention. For example, conventional methods such as blending the above components and kneading them at room temperature or under heating using a mixer, roll, kneader, etc., or dissolving and mixing the above components using a small amount of a suitable solvent can be employed.

[0116] A curable composition according to one embodiment of the present invention can exhibit good adhesion to various substrates such as plastics, metals, and composite materials. Furthermore, when used as an adhesive for non-polar materials such as polypropylene or engineering plastics having rigid molecular chains such as polyphenylene sulfide, the substrate can be pre-treated by known methods to enhance adhesion to these substrates 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 less damage to the substrate and provides stable adhesion. These surface treatments are also effective in removing mold release agents that remain on the substrate surface after molding.

[0117] The cured product obtained by curing the curable composition according to one embodiment of the present invention has good adhesion to various substrates, and therefore the curable composition can be used as an adhesive, sealant, or tack. 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, allowing it to be applied to a substrate, and therefore can be suitably used as a hot-melt type curable composition, especially a hot-melt type adhesive.

[0118] In order to ensure workability when applying the curable composition according to one embodiment of the present invention to a substrate, it is preferable to heat it to a high temperature to reduce its viscosity, preferably around 70 to 180°C, more preferably 90 to 160°C, and even more preferably 100 to 150°C. The method of heating is not particularly limited, and conventionally known methods can be used.

[0119] A curable composition according to one embodiment of the present invention can exhibit desired physical properties by performing a long curing (curing) process after bonding the adherends. The conditions for the curing (curing) process are not particularly limited, but examples include a temperature of 5 to 90°C and a duration of 24 hours to 1 week.

[0120] 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 as an adhesive for joining panels of buses, trailers, trains, etc., as an adhesive for joining displays and housings in smartphones, tablet devices, and laptop computers, as an adhesive for clothing, 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. As the sealer, a polymer having reactive silicon groups as shown in this application can be used.

[0121] More specifically, the curable composition according to one embodiment of the present invention is preferably used as an adhesive in automotive parts such as vehicle panels, large vehicle parts such as trucks and buses, train car parts, aircraft parts, ship parts, electrical parts, and various mechanical parts.

[0122] The following sections list preferred embodiments of this disclosure. [1] General formula (1):-SiR 1 3-a X a (1) (In the formula, R 1A graft copolymer is formed by bonding a (meth)acrylic acid ester polymer block (A) having a reactive silicon group represented by ( ) and a polyoxyalkylene polymer block (B) having a number average molecular weight of 10,000 to 20,000 and a molecular weight distribution (Mw / Mn) of 1.0 to 1.5 in the order ABA, wherein the proportion of polymer block (A) in the graft copolymer is 35 to 70% by weight and the proportion of polymer block (B) is 30 to 65% by weight, and the polymer block (A) is (meth)acrylic acid ester A graft copolymer comprising structural units derived from tel(a1) and structural units derived from a chain transfer agent (a2) having a mercapto group, wherein the content of alkyl (meth)acrylate ester having 4 or more C atoms in the alkyl group is 2% by weight or more and 12% by weight or less in the graft copolymer, the reactive silicon group equivalent derived from (meth)acrylate ester (a1) is 0.15 mmol / g or less, and the sulfur atom concentration derived from the chain transfer agent (a2) is 4,000 to 10,000 ppm in the graft copolymer. [2] The graft copolymer according to [1], wherein the molar ratio of the polyoxyalkylene polymer block (B) to the chain transfer agent (a2) is 0.06 to 0.30. [3] The graft copolymer according to [1] or [2], wherein the molecular weight distribution (Mw / Mn) of the polyoxyalkylene polymer block (B) is 1.4 or less. [4] The bonding form between the polymer block (A) and the polymer block (B) is given by general formula (2) or (3): AC(=O)-OR-NH-C(=O)-OB (2) AC(=O)-OB (3) A graft copolymer as described in [1] or [2], represented by (wherein A represents polymer block (A), B represents polymer block (B), and R represents a divalent hydrocarbon group having 1 to 20 carbon atoms). [5] A curable composition comprising the graft copolymer described in [1] or [2]. [6] A hot-melt adhesive comprising the graft copolymer described in [1] or [2]. [Examples]

[0123] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the present invention.

[0124] The number-average molecular weight and weight-average molecular weight in the examples are GPC molecular weights measured under the following conditions. Liquid delivery system: Tosoh HLC-8120GPC Column: Tosoh TSK-GEL H type Solvent: THF Molecular weight: Polystyrene equivalent Measurement temperature: 40℃

[0125] The molecular weights in the examples, calculated using end-group ratios, were determined by determining the hydroxyl value according to the measurement method of JIS K 1557 and the iodine value according to the measurement method of JIS K 0070, taking into account the structure of the organic polymer (degree of branching determined by the polymerization initiator used).

[0126] The average number of carbon-carbon unsaturated bonds introduced to each terminal of the polymer shown in the examples was calculated using the following formula. (Average number of introduced groups) = [Unsaturated group concentration of polymer determined from iodine value (mol / g) - Unsaturated group concentration of precursor polymer determined from iodine value (mol / g)] / [Hydrogenous group concentration of precursor polymer determined from hydroxyl value (mol / g)]

[0127] (Sulfur atom concentration) The sulfur atom concentration is a theoretical value calculated from the total amount of components used in the production of the graft copolymer and the amount of chain transfer agent (a2) containing mercapto groups.

[0128] (Synthesis Example 1) Using polyoxypropylene glycol with a number-average molecular weight of approximately 4,020 (end-group molecular weight of 2,980) as an initiator, polymerization of propylene oxide was carried out using a zinc hexacyanocobaltate grime complex catalyst to obtain polyoxypropylene with hydroxyl groups at both ends, a number-average molecular weight of 14,600 (end-group molecular weight of 9,130), and a molecular weight distribution Mw / Mn = 1.15. 60 ppm of U-360 (dibutyltinbis(isooctyl mercaptopropionate, Nitto Chemical Co., Ltd.)) was added to the obtained polyoxypropylene, and 0.95 equivalents of Karenz AOI (2-isocyanate ethyl acrylate, Showa Denko K.K.) were added dropwise to the hydroxyl groups of the polyoxypropylene. The reaction was carried out at 90°C for 1 hour in a nitrogen atmosphere to obtain a polyoxyalkylene polymer (b-1) having acryloyl groups at both ends (i.e., approximately 2 acryloyl groups per polymer molecule), a number average molecular weight of 14,600, and a weight average molecular weight of 16,790.

[0129] (Synthesis Example 2) Using polyoxypropylene glycol with a number-average molecular weight of approximately 4,020 (end-group molecular weight of 2,980) as an initiator, propylene oxide was polymerized using a zinc hexacyanocobaltate grime complex catalyst to obtain polyoxypropylene with hydroxyl groups at both ends, a number-average molecular weight of 8,900 (end-group molecular weight of 5,900), and a molecular weight distribution Mw / Mn = 1.07. 60 ppm of U-360 was added to the obtained polyoxypropylene, and 0.93 equivalents of Karenz AOI were added dropwise to the hydroxyl groups of the polyoxypropylene. The reaction was carried out at 90°C for 1 hour in a nitrogen atmosphere to obtain a polyoxyalkylene polymer (p-1) with acryloyl groups at both ends (i.e., approximately 2 acryloyl groups per polymer molecule), a number-average molecular weight of 8,900, and a weight-average molecular weight of 9,500.

[0130] (Synthesis Example 3) Using polyoxypropylene glycol with a number-average molecular weight of approximately 4,020 (end-group molecular weight of 2,980) as an initiator, propylene oxide was polymerized using a zinc hexacyanocobaltate grime complex catalyst to obtain polyoxypropylene with hydroxyl groups at both ends, a number-average molecular weight of 21,100 (end-group molecular weight of 13,600), and a molecular weight distribution Mw / Mn = 1.21. 60 ppm of U-360 was added to the obtained polyoxypropylene, and 0.93 equivalents of Karenz AOI were added dropwise to the hydroxyl groups of the polyoxypropylene. The reaction was carried out at 90°C for 1 hour in a nitrogen atmosphere to obtain a polyoxyalkylene polymer (p-2) with acryloyl groups at both ends (i.e., approximately 2 acryloyl groups per polymer molecule), a number-average molecular weight of 21,100, and a weight-average molecular weight of 24,930.

[0131] (Synthesis Example 4) 42.2 parts by weight of butyl acetate were placed in a four-necked flask equipped with a stirrer, and the temperature was raised to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 39.9 parts by weight of methyl methacrylate, 6.0 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (A-1) with a number average molecular weight of 3,880 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.033 mmol / g, a reactive silicon group equivalent of 0.26 mmol / g, and a sulfur atom concentration of 5,217 ppm.

[0132] (Synthesis Example 5) 42.2 parts by weight of butyl acetate was placed in a four-necked flask equipped with a stirrer and heated to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 36.9 parts by weight of methyl methacrylate, 9.0 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (A-2) with a number average molecular weight of 4,100 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.033 mmol / g, a reactive silicon group equivalent of 0.26 mmol / g, and a sulfur atom concentration of 5,217 ppm.

[0133] (Synthesis Example 6) 42.2 parts by weight of butyl acetate were placed in a four-necked flask equipped with a stirrer, and the temperature was raised to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 42.9 parts by weight of methyl methacrylate, 3.0 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was then added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (A-3) with a number average molecular weight of 3,870 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.033 mmol / g, a reactive silicon group equivalent of 0.26 mmol / g, and a sulfur atom concentration of 5,217 ppm.

[0134] (Synthesis Example 7) 42.2 parts by weight of butyl acetate were placed in a four-necked flask equipped with a stirrer, and the temperature was raised to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 40.5 parts by weight of methyl methacrylate, 6.0 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 2.6 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (A-4) with a number average molecular weight of 4,570 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.036 mmol / g, a reactive silicon group equivalent of 0.23 mmol / g, and a sulfur atom concentration of 4,238 ppm.

[0135] (Synthesis Example 8) 42.2 parts by weight of butyl acetate was placed in a four-necked flask equipped with a stirrer and heated to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 34.9 parts by weight of methyl methacrylate, 6.0 parts by weight of butyl acrylate, 53.0 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.6 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids content) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (A-5) with a number average molecular weight of 3,770 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.036 mmol / g, a reactive silicon group equivalent of 0.28 mmol / g, and a sulfur atom concentration of 5,869 ppm.

[0136] (Synthesis Example 9) 42.2 parts by weight of butyl acetate were placed in a four-necked flask equipped with a stirrer, and the temperature was raised to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 39.9 parts by weight of methyl methacrylate, 4.5 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 4.0 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was then added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (P-1) with a number average molecular weight of 3,910 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.033 mmol / g, a reactive silicon group equivalent of 0.32 mmol / g, and a sulfur atom concentration of 5,217 ppm.

[0137] (Synthesis Example 10) 42.2 parts by weight of butyl acetate were placed in a four-necked flask equipped with a stirrer, and the temperature was raised to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 45.9 parts by weight of methyl methacrylate, 48.4 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was then added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids content) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (P-2) with a number average molecular weight of 4,100 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.033 mmol / g, a reactive silicon group equivalent of 0.26 mmol / g, and a sulfur atom concentration of 5,217 ppm.

[0138] (Synthesis Example 11) 42.2 parts by weight of butyl acetate were placed in a four-necked flask equipped with a stirrer, and the temperature was raised to 115°C under a nitrogen atmosphere. A mixed solution of 41.8 parts by weight of methyl methacrylate, 50.0 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 1.4 parts by weight of 3-methacryloxypropyltrimethoxysilane, 6.8 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) dissolved in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution of 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) dissolved in 5.7 parts by weight of butyl acetate was then added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (P-3) with a number average molecular weight of 1,930 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.034 mmol / g, a reactive silicon group equivalent of 0.40 mmol / g, and a sulfur atom concentration of 11,085 ppm.

[0139] (Synthesis Example 12) 42.2 parts by weight of butyl acetate was placed in a four-necked flask equipped with a stirrer and heated to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 39.9 parts by weight of methyl methacrylate, 6.0 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (p-1) prepared in Synthesis Example 2, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was then added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (P-4) with a number average molecular weight of 4,190 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.054 mmol / g, a reactive silicon group equivalent of 0.26 mmol / g, and a sulfur atom concentration of 5,217 ppm.

[0140] (Synthesis Example 13) 42.2 parts by weight of butyl acetate was placed in a four-necked flask equipped with a stirrer and heated to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 39.9 parts by weight of methyl methacrylate, 6.0 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (p-2) prepared in Synthesis Example 3, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. A mixed solution prepared by dissolving 0.3 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 5.7 parts by weight of butyl acetate was added, and polymerization was carried out at 115°C for 2 hours to obtain a butyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (P-5) with a number average molecular weight of 3,730 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.023 mmol / g, a reactive silicon group equivalent of 0.26 mmol / g, and a sulfur atom concentration of 5,217 ppm.

[0141] (Example 1) The butyl acetate solution of the graft copolymer obtained in Synthesis Example 4 was heated and defoliated to obtain a solid graft polymer (A-1) at room temperature. (Adhesive strength) 100 parts by weight of graft copolymer (A-1) was heated and melted at 140°C, and 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.2 parts by weight of U-810 (dioctyl tin dilaurate, manufactured by Nitto Chemical Co., Ltd.) were added and mixed to obtain a curable composition. The curable composition was applied to beech wood to an adhesive area of ​​25 mm × 12.5 mm and a thickness of 0.1 mm, and the other adherend was bonded to it. The time of bonding was taken as the start time, and after curing for 1 hour under 23°C and 50% RH conditions, the shear bond strength was measured at a test speed of 10 mm / min. The results are shown in Table 1. (Recovery rate) 100 parts by weight of graft copolymer (A-1) was heated and melted at 140°C, and 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.2 parts by weight of U-810 (dioctyl tin dilaurate, manufactured by Nitto Kasei Co., Ltd.) were added and mixed to prepare a sheet with a thickness of approximately 2 mm, which was cured for 7 days under conditions of 23°C and 50% RH. The obtained sheet was punched out into a No. 3 dumbbell shape (JIS K 6251). The obtained No. 3 dumbbell was stretched to 100%, held in that state at 50°C for 24 hours, then released, and after standing at 23°C for 1 hour, the recovery rate was measured. The recovery rate was calculated using the following formula. Formula: 100 × {(distance between gauge marks when fully extended) - (distance between gauge marks after standing)} / {(distance between gauge marks when fully extended) - (distance between gauge marks before extension)}. The results are shown in Table 1. Furthermore, various data were obtained for Examples 2-5 and Comparative Examples 1-5 in the same manner as described in Example 1 (Table 1).

[0142] [Table 1]

[0143] Examples 1-5 show that the initial adhesive strength measured one hour after bonding was sufficiently high, indicating a high recovery rate of the cured material.

[0144] On the other hand, graft copolymer (P-1) in which the reactive silicon group equivalent derived from acrylic monomer (a1) exceeded 0.15 mmol / g fractured during the measurement of the recovery rate due to the low elongation at break of the cured product (Comparative Example 1).

[0145] When evaluating graft copolymers (P-2 and P-3) that did not contain alkyl (meth)acrylate esters with four or more C1s, P-2 showed a low curing rate (Comparative Example 2). Furthermore, P-3, which had a sulfur atom concentration exceeding 10,000 ppm derived from the chain transfer agent (a2), showed extremely low adhesive strength after 1 hour (Comparative Example 3).

[0146] P-4, copolymerized with a macromonomer (p-1) having a number-average molecular weight of less than 10,000 in polymer block (B), fractured during the measurement of the recovery rate (Comparative Example 4). P-5, copolymerized with a macromonomer (p-2) having a number-average molecular weight of over 20,000 in polymer block (B), showed low adhesive strength after 1 hour (Comparative Example 5).

Claims

1. General formula (1): -SiR １ ３－ａ X ａ (1) (In the formula, R １ (where represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. X represents a hydroxyl group or a hydrolyzable group. a indicates 2 or 3.) A graft copolymer is formed in which a (meth)acrylic acid ester polymer block (A) having reactive silicon groups represented by and a polyoxyalkylene polymer block (B) having a number average molecular weight of 10,000 to 20,000 and a molecular weight distribution (Mw / Mn) of 1.0 to 1.5 are linked in the order A-B-A. In the graft copolymer, the proportion of polymer block (A) is 35 to 70% by weight, and the proportion of polymer block (B) is 30 to 65% by weight. The polymer block (A) comprises a structural unit derived from (meth)acrylic acid ester (a1) and a structural unit derived from a chain transfer agent (a2) having a mercapto group. The content of alkyl (meth)acrylate esters with 4 or more C12 atoms in the graft copolymer is 2% by weight or more and 12% by weight or less. The reactive silicon group equivalent derived from (meth)acrylic acid ester (a1) is 0.15 mmol / g or less. A graft copolymer in which the sulfur atom concentration derived from the chain transfer agent (a2) is 4,000 to 10,000 ppm in the graft copolymer.

2. The graft copolymer according to claim 1, wherein the molar ratio of the polyoxyalkylene polymer block (B) to the chain transfer agent (a2) is 0.06 to 0.

30.

3. The graft copolymer according to claim 1 or 2, wherein the molecular weight distribution (Mw / Mn) of the polyoxyalkylene polymer block (B) is 1.4 or less.

4. The bonding form between polymer block (A) and polymer block (B) is general formula (2) or (3): AC(=O)-OR-NH-C(=O)-OB (2) AC(=O)-OB (3) A graft copolymer according to claim 1 or 2, represented by the formula (wherein A represents polymer block (A), B represents polymer block (B), and R represents a divalent hydrocarbon group having 1 to 20 carbon atoms).

5. A curable composition comprising the graft copolymer described in claim 1 or 2.

6. A hot-melt adhesive comprising the graft copolymer described in claim 1 or 2.

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