Hot-melt curable composition and hot-melt adhesive

Abstract

This hot-melt curable composition comprises: a graft copolymer (P) in which a (meth) acrylic acid ester polymer block (A) having a reactive silicon group represented by -SiR1 3-aXa (where R1 represents a 1-20C substituted or unsubstituted hydrocarbon group; X represents a hydroxyl group or a hydrolyzable group; a represents 2 or 3) and a polymer block (B) selected from the group consisting of a (meth) acrylic acid ester polymer block, a polyoxyalkylene polymer block, and a hydrocarbon-based polymer block, are bonded in the order of A-B-A; and a reactive silicon group-containing compound (C) having a boiling point at atmospheric pressure of 150°C or higher and having no amino group.

Description

Hot-melt curable composition and hot-melt adhesive 【0001】 The present invention relates to a hot-melt curable composition comprising a graft copolymer having reactive silicon groups, and a hot-melt adhesive comprising the composition. 【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 rubber-like cured products can be obtained when such organic polymers are crosslinked by the siloxane condensation reaction of reactive silicon groups. 【0003】 As one example of an organic polymer having such reactive silicon groups, Patent Document 1 discloses a (meth)acrylic acid ester copolymer having reactive silicon groups, which is composed of a (meth)acrylic acid ester, a polymer having one or more (meth)acryloyl groups in its molecule, and a chain transfer agent having mercapto groups. This copolymer constitutes a graft copolymer formed by the bonding of three polymer blocks. 【0004】 The aforementioned document discloses that a curable composition containing the copolymer can be used as a hot-melt type curable composition. A hot-melt type curable composition is a composition that is solid at room temperature but becomes fluid when heated and melted, allowing it to be applied to a substrate. 【0005】 On the other hand, compositions containing organic polymers having reactive silicon groups are known to harden during storage due to the reaction of the reactive silicon groups with water. Therefore, it is known that dehydrating agents such as vinyltrimethoxysilane are added to such compositions in order to improve storage stability. 【0006】 International Publication No. 2023 / 132324 【0007】The inventors of this application attempted to improve the storage stability of a hot-melt curable composition containing a graft copolymer, such as that disclosed in Patent Document 1, by incorporating vinyltrimethoxysilane, which is widely used as a dehydrating agent for organic polymers having reactive silicon groups. However, it was found that vinyltrimethoxysilane volatilizes when the components are heated and mixed to prepare the composition, or when the composition is heated and melted. 【0008】 In view of the above situation, the present invention aims to provide a hot-melt type curable composition comprising a reactive silicon group-containing graft copolymer that exhibits good storage stability and suppresses volatility upon heating. 【0009】 As a result of diligent research to solve the above problems, the present inventors have found that the above problems can be solved by incorporating a reactive silicon group-containing compound having a specific configuration into a hot-melt type curable composition containing a reactive silicon group-containing graft copolymer, and have completed the present invention. 【0010】 In other words, the present invention relates to the general formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １ The present invention relates to a hot-melt curable composition containing a graft copolymer (P) in which a (meth)acrylic acid ester polymer block (A) having a reactive silicon group represented by (meth)acrylic acid ester polymer block, a polymer block (B) selected from the group consisting of (meth)acrylic acid ester polymer blocks, polyoxyalkylene polymer blocks, and hydrocarbon polymer blocks are bonded in the order A-B-A, and a reactive silicon group-containing compound (C) having a boiling point of 150°C or higher at atmospheric pressure and lacking an amino group. The present invention also relates to a hot-melt curable composition containing the above hot-melt curable composition. 【0011】According to the present invention, it is possible to provide a hot-melt type curable composition containing a reactive silicon group-containing graft copolymer that exhibits good storage stability and suppresses volatility upon heating. 【0012】 The hot-melt curable composition according to the present invention is solid at room temperature and becomes fluid when heated and melted, allowing it to be applied to a substrate. After application, it cools and solidifies, and a curing reaction proceeds through the hydrolysis and condensation reaction of reactive silicon groups. 【0013】 Conceptual diagram of an H-type structure that may be contained in a graft copolymer (P) 【0014】 Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below, and various modifications are possible within the scope defined in the claims. Furthermore, the configurations described below can be combined arbitrarily, and such combinations may also constitute an embodiment of the present invention. 【0015】 The hot-melt curable composition according to this disclosure contains at least a graft copolymer having reactive silicon groups (P) and a reactive silicon group-containing compound without amino groups (C). The hot-melt curable composition is solid at room temperature and becomes fluid when heated and melted, allowing it to be applied to a substrate. 【0016】 <<Graft Copolymer (P)>> The graft copolymer (P) in this disclosure is formed by bonding a (meth)acrylic acid ester polymer block (A) and a polymer block (B) selected from the group consisting of (meth)acrylic acid ester polymer blocks, polyoxyalkylene polymer blocks, and hydrocarbon polymer blocks. The graft copolymer (P) has reactive silicon groups, which are bonded to polymer block (A). Polymer block (A) and polymer block (B) have different compositions of constituent monomers, and as a result, they exhibit different glass transition temperatures. In this application, "(meth)acrylic" means "acrylic and / or methacrylic". 【0017】<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.) 【0018】 R １ preferably has 1 to 10 carbon atoms in the hydrocarbon group, 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 an 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. 【0019】 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 preferable because of its mild hydrolyzability and easy handling, and a methoxy group and an ethoxy group are particularly preferable. 【0020】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. 【0021】 The reactive silicon group equivalent of the graft copolymer (P) is preferably 0.15 mmol / g or more. This enhances the initial fixation after heating and melting the hot-melt curable composition according to this disclosure, and also allows for the production of a high-strength cured product. Preferably, it is 0.20 mmol / g or more, and more preferably 0.25 mmol / g or more. Furthermore, there is no particular upper limit to the reactive silicon group equivalent, but it is preferably 0.5 mmol / g or less, more preferably 0.4 mmol / g or less, and even more preferably 0.30 mmol / g or less. 【0022】The equivalent weight of the reactive silicon group shown by the graft polymer (P) is calculated by dividing the total silicon group equivalent weight of the reactive silicon group-containing components constituting the graft polymer (P) by the total weight of the components constituting the graft polymer (P). Specifically, it can be calculated by dividing the total silicon group equivalent weight obtained by summing the silicon equivalent weight of the (meth)acrylic acid ester (a1-2) having a reactive silicon group and the silicon equivalent weight of the chain transfer agent (a2) having a reactive silicon group by the total weight of the monomers and the chain transfer agent constituting the graft polymer (P). 【0023】 <(Meth)acrylate polymer block (A)> The polymer block (A) is a polymer block containing at least a structural unit derived from the (meth)acrylic acid ester (a1). 【0024】<(meth)acrylic acid ester (a1)> (meth)acrylic acid ester (a1) is broadly classified into (meth)acrylic acid ester (a1-1) which does not have a reactive silicon group and (meth)acrylic acid ester (a1-2) which has 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)acrylic acid ester (a1-1) having no reactive silicon group, an alkyl (meth)acrylate is preferable. 【0025】 As the (meth)acrylic acid ester (a1-1) having no reactive silicon group, an alkyl (meth)acrylate having 7 or more carbon atoms in the alkyl group may or may not be used. However, when the polymer block (B) contains a (meth)acrylic acid ester polymer block and / or a polyoxyalkylene polymer block, it is preferable to set the content in the range of 0 wt% or more and 10 wt% or less in the graft copolymer (P). By reducing the amount of the alkyl (meth)acrylate having a long-chain alkyl group used, the initial fixability after heating and melting the hot-melt curable composition can be enhanced, and a cured product with high strength can be obtained. The upper limit of the content is preferably 8 wt% or less, more preferably 7 wt% or less, still more preferably 5 wt% or less, and particularly preferably 3 wt% or less. Also, it may be 1 wt% or less, or 0 wt%. Further, the upper limit of the carbon number of the alkyl is not particularly limited, but may be 20 or less, 15 or less, or 12 or less. 【0026】 When the polymer block (B) contains a (meth)acrylic acid ester polymer block and / or a polyoxyalkylene polymer block, the (meth)acrylic acid ester (a1-1) having no reactive silicon group preferably contains at least an alkyl (meth)acrylate having 3 or less carbon atoms in the alkyl group, and it is preferable to set the content of the monomer in the graft copolymer (P) to 25 wt% or more. Thereby, the initial fixability after heating and melting the hot-melt curable composition can be further enhanced, and a cured product with even higher strength can be obtained. Preferably it is 30 wt% or more, more preferably 35 wt% or more, still more preferably 40 wt% or more. 【0027】On the other hand, the upper limit of the content of alkyl (meth)acrylate esters with three or fewer carbon atoms in the alkyl group is preferably 60% by weight or less, more preferably 50% by weight or less, and particularly preferably 45% by weight or less, in the graft copolymer (P) from the viewpoint of lowering the viscosity of the graft copolymer (P) or the hot-melt curable composition when heated and melted. 【0028】 As the alkyl (meth)acrylate ester with three or fewer C atoms in the alkyl group, alkyl methacrylate esters with three or fewer C atoms in the alkyl group are preferred, and methyl methacrylate is particularly preferred, from the viewpoint of improving initial fixation and obtaining a high-strength cured product. 【0029】 When polymer block (B) includes a (meth)acrylic acid ester polymer block and / or a polyoxyalkylene polymer block, butyl acrylate may or may not be used as the (meth)acrylic acid ester (a1-1) that does not have reactive silicon groups. However, its content is preferably 0% to 8% by weight in the graft copolymer (P) because it can improve the strength of the cured product. The upper limit is more preferably 6% by weight or less, even more preferably 4% by weight or less, and particularly preferably 3% by weight or less. The lower limit is preferably 0.1% by weight or more, and more preferably 0.3% by weight or less. 【0030】 When polymer block (B) includes a hydrocarbon polymer block, the (meth)acrylic acid ester (a1-1) that does not have reactive silicon groups preferably contains at least an alkyl (meth)acrylic acid ester with four or more C12 atoms in the alkyl group, and it is preferable to set the content of this monomer to 10% by weight or more in the graft copolymer (P). This increases the compatibility between polymer block (B) and (meth)acrylic acid ester (a1) during the production of the graft copolymer, making it possible to produce a graft copolymer that exhibits good physical properties. Preferably, it is 20% by weight or more, more preferably 30% by weight or more. 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. 【0031】As the alkyl (meth)acrylate ester having four or more carbon atoms in the alkyl group, alkyl acrylate esters having four or more carbon atoms in the alkyl group are preferred, and butyl acrylate is particularly preferred. 【0032】 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 polymer block (A). 【0033】 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. 【0034】 When using a (meth)acrylic acid ester (a1-2) having a reactive silicon group, the content of (a1-2) is preferably 1% by weight or more and 30% by weight or less of the total amount of constituent units forming the polymer block (A), more preferably 2% by weight or more and 20% by weight or less, even more preferably 3% by weight or more and 15% by weight or less, and particularly preferably 5% by weight or more and 10% by weight or less. 【0035】 From the viewpoint of imparting good physical properties to the cured product, the content of (meth)acrylic acid ester (a1) in polymer block (A) is preferably 30% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, particularly preferably 60% by weight or more, and particularly preferably 70% by weight or more, of the total amount of constituent units forming polymer block (A). The upper limit is preferably 100% by weight or less, and more preferably 95% by weight or less. 【0036】<Chain transfer agent having a mercapto group (a2)> It is preferable that the polymer block (A) contains constituent units derived from the chain transfer agent having a mercapto group (a2). By using the chain transfer agent having a mercapto group (a2), the molecular weight of the polymer block (A) can be controlled. In addition, the molecular weight distribution of the graft copolymer (P) can be made relatively narrow, and gelation during the synthesis of the graft copolymer (P) can be suppressed. Furthermore, it becomes possible to preferentially synthesize polymer molecules in which one polymer block (B) is introduced into one molecule of the graft copolymer (P). 【0037】 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 polymer block (A). 【0038】 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. 【0039】 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 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 7% by weight or less. 【0040】 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 polymer block (A). 【0041】 The ratio of polymer block (B) content to chain transfer agent (a2) content having mercapto groups is preferably 0.10 or higher, more preferably 0.15 or higher, even more preferably 0.20 or higher, even more preferably 0.25 or higher, and particularly preferably 0.30 or higher, as this improves initial fixation. The upper limit of the above molar ratio is preferably 0.40 or lower, and more preferably 0.35 or lower, as this reduces viscosity during heating and melting. 【0042】 When polymer block (A) is formed using a chain transfer agent (a2) having a mercapto group, polymer block (A) has substituents (described later -S-R) derived from the chain transfer agent (a2) having a mercapto group. ８ It has a structure represented by . Therefore, the polymer block (A) or graft copolymer (P) may contain sulfur atoms. 【0043】 The sulfur atom concentration derived from the chain transfer agent (a2) is preferably 4,500 ppm to 10,000 ppm in the graft copolymer (P). This sulfur atom concentration is a value relative to the solid content of the graft copolymer (P), and the solvent is excluded from its calculation. 【0044】 The sulfur atom concentration is a value that reflects the proportion of the chain transfer agent used in the graft copolymer (P). When the sulfur atom concentration is 4,500 ppm or higher, excessive molecular weight increase of the polymer block (A) is suppressed, and as a result, the viscosity of the graft copolymer (P) or the hot-melt curable composition during heating and melting can be further reduced. Furthermore, when the sulfur atom concentration is 10,000 ppm or lower, the initial fixation is improved. 【0045】 The lower limit of the sulfur atom concentration is preferably 4,500 ppm or more, more preferably 5,000 ppm or more. The upper limit is preferably 8,000 ppm or less, even more preferably 6,000 ppm or less, and particularly preferably 5,500 ppm or less. 【0046】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 (P) and the amount of the chain transfer agent (a2) having a mercapto group. 【0047】 Polymer block (A) may have reactive silicon groups by satisfying either or both of the following two conditions: Condition 1: (meth)acrylic acid ester (a1) contains (meth)acrylic acid ester (a1-2) having reactive silicon groups. Condition 2: The chain transfer agent (a2) having mercapto groups further has reactive silicon groups. 【0048】 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 from (a1) is preferably 0.01 mmol / g or more, and more preferably 0.10 mmol / g or more, from the viewpoint of the resilience of the cured product. Furthermore, the reactive silicon group equivalent from (a1) is preferably 0.40 mmol / g or less, more preferably 0.30 mmol / g or less, and even more preferably 0.15 mmol / g or less, from the viewpoint of the elongation of the cured product. 【0049】 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. 【0050】 The reactive silicon group equivalent derived from (a1) or (a2) can be calculated in accordance with the method for calculating the reactive silicon group equivalent of the graft copolymer (P) described above. 【0051】 The components forming the polymer block (A) may or may not contain other monomers (a3) ​​that do not fall under either (a1) or (a2) as described above. 【0052】 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. 【0053】 <Polymer Block (B)> Polymer block (B) is selected from the group consisting of (meth)acrylic acid ester polymer blocks, polyoxyalkylene polymer blocks, and hydrocarbon polymer blocks. Each embodiment will be described below. 【0054】<(meth)acrylic acid ester polymer block> In an embodiment in which polymer block (B) is a (meth)acrylic acid ester polymer block, (meth)acrylic monomers can be used as monomers constituting the main chain skeleton of the polymer block. A specific example is the (meth)acrylic acid ester (a1-1) that does not have a reactive silicon group, as exemplified in polymer block (A). These monomers may be used individually or in combination of two or more. Furthermore, (meth)acrylic acid esters having a reactive silicon group may be used in polymer block (B), but it is preferable not to use them. 【0055】 From the viewpoint of imparting good physical properties to the cured product, the content of (meth)acrylic monomers in polymer block (B) is preferably 30% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, particularly preferably 60% by weight or more, and particularly preferably 70% by weight or more, of the total amount of constituent units forming polymer block (B). The upper limit is 100% by weight or less. 【0056】 The monomers constituting the main chain skeleton of polymer block (B) may be (meth)acrylic monomers in combination with other monomers that exhibit copolymerizability with said monomers. Examples of other monomers include those exemplified as other monomers (a3) ​​with respect to polymer block (A). Only one type of other monomer may be used, or two or more types may be used in combination. 【0057】 The polymer block (B) is preferably composed of a soft polymer, i.e., a polymer with a low glass transition temperature. Therefore, in the embodiment where the polymer block (B) is a (meth)acrylic acid ester polymer block, it is preferable that the polymer block (B) is an acrylic acid ester polymer block. An acrylic acid ester polymer block refers to a polymer block formed with acrylic acid ester as the main monomer component. 【0058】The monomer components forming the acrylic acid ester polymer block preferably contain 60% by weight or more of acrylic acid ester, more preferably 70% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more. The upper limit may be 100% by weight or less. 【0059】 The acrylic acid ester forming the aforementioned acrylic acid ester polymer block is preferably an alkyl acrylate other than isobornyl acrylate, dicyclopentenyl acrylate, or dicyclopentanyl acrylate, more preferably an alkyl acrylate with two or more carbon atoms in the alkyl group, and particularly preferably butyl acrylate. 【0060】 Polymer block (B), which is a (meth)acrylic acid ester polymer block, may have a reactive silicon group represented by the general formula (1) bonded to it, but it is preferable that it does not have a reactive silicon group bonded to it. That is, it is preferable not to use a (meth)acrylic acid ester having a reactive silicon group as the monomer that forms polymer block (B). 【0061】 <Polyoxyalkylene Polymer Block> In embodiments where polymer block (B) is a polyoxyalkylene polymer block, the polyoxyalkylene polymer constituting the polymer block is not particularly limited, and examples include polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymer, and polyoxypropylene-polyoxybutylene copolymer. Among these, polyoxypropylene is preferred. 【0062】 The main chain skeleton of the polyoxyalkylene polymer may be linear or branched, but it is preferable that it be linear. 【0063】 <Hydrogen-based polymer block> In an embodiment where the polymer block (B) is a hydrocarbon-based polymer, the graft copolymer (P) exhibits thixotropy, and after curing, improved strength and reduced water permeability can be achieved. 【0064】The aforementioned hydrocarbon polymers refer to those having a polymer backbone formed by the polymerization of unsaturated hydrocarbon compounds such as olefins and dienes. Specific examples include polyisobutylene polymers and diene polymers. From the viewpoint of improving the strength of the cured product, reducing moisture permeability, and improving thixotropy, polyisobutylene polymers are preferred. 【0065】 The polyisobutylene polymer is a polymer whose main constituent monomer is isobutene. It may be a polymer containing only isobutene as a constituent monomer, or it may be a copolymer having comonomers other than isobutene. Examples of such comonomers include aliphatic olefins (such as 1-butene); aromatic vinyl compounds (such as styrene, methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and α-methylstyrene); dienes (such as 1,3-butadiene and isoprene); vinyl ethers (such as butyl vinyl ether); silanes (such as vinyltrimethylsilane and allyltrimethylsilane); terpenes (such as α-pinene, β-pinene, and limonene); vinylcarbazoles; and acenaphthylene. Because copolymerization with isobutene is easy and the properties of the resulting copolymer are desirable, it is preferable to use one or more comonomers 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. 【0066】 The comonomer content in the polyisobutylene polymer is preferably less than 50% by weight of the total of isobutene and comonomers, more preferably 30% by weight or less, and even more preferably 10% by weight or less. 【0067】The aforementioned diene polymer refers to a polymer whose main component is a diene as a 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 type of diene may be used, or two or more types may be used in combination. Among these, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is particularly preferred. 【0068】 The diene polymer may be a polymer containing only a diene as a constituent monomer, or it may be a copolymer having comonomers other than a diene. As such comonomers, those listed above that can be used in polyisobutylene polymers can be used. Among these, aromatic vinyl compounds are preferred, and styrene is particularly preferred. 【0069】 The comonomer content in the diene polymer is preferably less than 50% by weight of the total of the diene and comonomer, more preferably 30% by weight or less, and even more preferably 10% by weight or less. 【0070】 The aforementioned diene polymer may be unhydrogenated or hydrogenated, but from the viewpoint of obtaining good heat resistance and weather resistance, hydrogenated polymer is preferred. 【0071】 Preferred examples of the diene polymer include polybutadiene polymers, polyisoprene polymers, hydrogenated polybutadiene polymers, hydrogenated polyisoprene polymers, and the like. 【0072】The aforementioned polybutadiene polymer or hydrogenated polybutadiene polymer is a polymer whose main constituent monomer is 1,3-butadiene. It may be a polymer containing only 1,3-butadiene as a constituent monomer, or it may be a copolymer having comonomers other than 1,3-butadiene. Examples of comonomers other than 1,3-butadiene include the aforementioned comonomers other than dienes and dienes other than 1,3-butadiene. 【0073】 The comonomer content in the polybutadiene polymer or hydrogenated polybutadiene polymer is preferably less than 50% by weight of the total of 1,3-butadiene and comonomers, more preferably 30% by weight or less, and even more preferably 10% by weight or less. 【0074】 The aforementioned polyisoprene polymer or hydrogenated polyisoprene polymer is a polymer whose main component is isoprene as a constituent monomer. It may be a polymer containing only isoprene as a constituent monomer, or it may be a copolymer having comonomers other than isoprene. Examples of comonomers other than isoprene include the aforementioned comonomers other than dienes, and dienes other than isoprene. 【0075】 The comonomer content in the polyisoprene polymer or hydrogenated polyisoprene polymer is preferably less than 50% by weight of the total of isoprene and comonomers, more preferably 30% by weight or less, and even more preferably 10% by weight or less. 【0076】 The number-average molecular weight of the polymer block (B) is preferably 7,000 or more. This allows the cured product obtained from the graft copolymer (P) to exhibit high strength. The number-average molecular weight is more preferably 8,000 or more, even more preferably 9,000 or more, and even more preferably 10,000 or more. The upper limit is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 18,000 or less, particularly preferably 15,000 or less, and most preferably 12,000 or less, from the viewpoint of achieving both initial fixation after heating and melting and low melt viscosity. 【0077】 The molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of the polymer block (B) is not particularly limited, but is preferably narrow, specifically 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, and the better the initial fixation tends to be. 【0078】 The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of polymer block (B) are values ​​measured in polystyrene equivalent by gel permeation chromatography (GPC) for the polyfunctional macromonomer (a4) described later. The detailed measurement method is described in the examples. 【0079】 Polymer block (B) can be introduced into graft copolymer (P) by using polymer (a4) having an average of more than one (meth)acryloyl group in its molecule. The main chain skeleton of polymer (a4) is selected from (meth)acrylic acid ester polymers, polyoxyalkylene polymers, and hydrocarbon polymers. Polymer (a4) can copolymerize with (meth)acrylic acid ester (a1) because it has (meth)acryloyl groups. Moreover, since polymer (a4) has more than one (meth)acryloyl group in its molecule, it can function as a so-called polyfunctional macromonomer. Hereinafter, polymer (a4) will also be referred to as "polyfunctional macromonomer (a4)". 【0080】 The (meth)acryloyl group of the polyfunctional macromonomer (a4) is not particularly limited, but can be represented by the following general formulas (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, R２ represents a hydrogen or methyl group. B represents the main chain skeleton of the polyfunctional macromonomer (a4), i.e., a (meth)acrylic acid ester polymer, a polyoxyalkylene polymer, or a hydrocarbon polymer. 【0081】 R in equation (2) ３ This 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. 【0082】 R in equation (4) ４ This represents a divalent saturated hydrocarbon group having 1 to 6 carbon atoms. Alkylene groups are particularly preferred, and specific examples include methylene, ethylene, propylene, butylene, pentylene, and hexylene groups. From the viewpoint of raw material availability and reactivity, butylene or pentylene groups are preferred. 【0083】 R in equation (4) ５ represents a phenylene group. The phenylene group may or may not have substituents on the benzene ring. Examples of substituents include monovalent hydrocarbon groups and alkoxy groups having 1 to 20 carbon atoms. Specific examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, 2-ethylhexyl, nonyl, and decanyl groups. Specific examples of alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy, and butoxy groups. Preferably, it is a methyl or methoxy group. 【0084】 The polyfunctional macromonomer (a4) has an average of 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. This average number is, for example, １ It can be calculated from the 1H NMR spectrum. 【0085】Furthermore, the polyfunctional macromonomer (a4) may have only an acryloyl group as the (meth)acryloyl group, or only a methacryloyl group, or it may have both an acryloyl group and a methacryloyl group. 【0086】 The polyfunctional macromonomer (a4) may have (meth)acryloyl groups at either the molecular chain ends or side chains of the polymer backbone, or both. From the viewpoint of excellent mechanical properties, it is preferable to have them at the molecular chain ends. In particular, it is especially preferable that the polyfunctional macromonomer (a4) has a linear main chain backbone and has (meth)acryloyl groups at both ends of its molecular chains. 【0087】 In embodiments where polymer block (B) is a (meth)acrylic acid ester polymer block, the method for synthesizing the polyfunctional macromonomer (a4) is not particularly limited, but for example, the following methods can be used. The following methods may be used in combination. (i) A method in which a monomer having a reactive functional group (V group) (e.g., acrylic acid, 2-hydroxyethyl acrylate) is copolymerized with a (meth)acrylic monomer, and then the resulting copolymer is reacted with a compound having a functional group that reacts with the V group and a (meth)acryloyl group (e.g., 2-isocyanate ethyl (meth)acrylic acid). (ii) A method in which a (meth)acrylic monomer is polymerized by living radical polymerization, and then (meth)acryloyl groups are introduced to the molecular chain ends (preferably both ends of the molecular chain). 【0088】Of these methods, method (ii) is preferred because it allows for the introduction of (meth)acryloyl groups at the molecular chain ends. Examples of "living radical polymerization" include methods using cobalt porphyrin complexes as shown in the Journal of the American Chemical Society (J.Am. Chem.Soc.), 1994, Vol. 116, p. 7943; methods using nitrooxide radicals as shown in Japanese Patent Publication No. 2003-500378; and atom transfer radical polymerization (ATRP method) using organic halides or sulfonyl halogen compounds as initiators and transition metal complexes as catalysts, as shown in Japanese Patent Publication No. 11-130931. Atom transfer radical polymerization is most preferred because it allows for the easy introduction of (meth)acryloyl groups at the molecular chain ends. 【0089】 Furthermore, it is also possible to use a method to obtain (meth)acrylic polymers using a metallocene catalyst and a thiol compound having at least one reactive silicon group in its molecule, as shown in Japanese Patent Application Publication No. 2001-040037. 【0090】 In embodiments where polymer block (B) is a polyoxyalkylene polymer block or a hydrocarbon polymer, the method for synthesizing the polyfunctional macromonomer (a4) is not particularly limited, but for example, one method is to prepare a polyoxyalkylene polymer or hydrocarbon polymer having one or more hydroxyl groups in the molecule (preferably a linear polyoxyalkylene polymer having hydroxyl groups at both ends or a linear hydrocarbon polymer having hydroxyl groups at both ends), and introduce (meth)acryloyl groups using these hydroxyl groups. 【0091】As an example of a method for synthesizing polyfunctional macromonomers (a4), a compound having an isocyanate group and a (meth)acryloyl group can be reacted with a polyoxyalkylene polymer or hydrocarbon polymer having a hydroxyl group to form a urethane bond and introduce a (meth)acryloyl group. Specific examples of the compound having an isocyanate group and a (meth)acryloyl group include, for example, isocyanate ethyl (meth)acrylate, isocyanate propyl (meth)acrylate, isocyanate butyl (meth)acrylate, and isocyanate hexyl (meth)acrylate. 【0092】 Another example of a method for synthesizing polyfunctional macromonomers (a4) is to introduce isocyanate groups into a polyoxyalkylene polymer or hydrocarbon polymer having hydroxyl groups by reacting a diisocyanate compound with the polymer, and then introduce (meth)acryloyl groups by reacting 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 the compounds having both hydroxyl groups and (meth)acryloyl groups include, for example, hydroxybutyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate. 【0093】As yet another example of a method for synthesizing polyfunctional macromonomers (a4), a carboxyl group can be introduced into a polyoxyalkylene polymer or hydrocarbon polymer having a hydroxyl group by reacting an acid anhydride with the polymer, and then a (meth)acryloyl group can be introduced by reacting the polymer with a compound having an epoxy group and a (meth)acryloyl group. Specific examples of the acid anhydrides include 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 the compounds having an epoxy group and a (meth)acryloyl group include glycidyl (meth)acrylate. 【0094】 Another example of a method for synthesizing polyfunctional macromonomers (a4) involves dehydration condensation of methacrylic acid or acrylic acid with a polyoxyalkylene polymer or hydrocarbon 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, or acrylate iodide are reacted with a polyoxyalkylene polymer containing hydroxyl groups. 【0095】 In embodiments where polymer block (B) is a hydrocarbon polymer, yet another example of a method for synthesizing a polyfunctional macromonomer (a4) is to form a polyisobutylene polymer main chain by living cationic polymerization of isobutylene in the presence of a bifunctional polymerization initiator, a Lewis acid catalyst, and an electron donor component, and then to introduce (meth)acryloyl groups to the ends of the main chain by reacting a compound having a benzene ring and a (meth)acryloyl group (e.g., a phenoxyalkyl (meth)acrylate compound). 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. 【0096】Examples of bifunctional polymerization initiators include p-dicumyl chloride and 1,4-bis(chloromethyl)benzene. An example of a Lewis acid catalyst is titanium tetrachloride. Examples of electron donor components include nitrogen-containing compounds (e.g., 2-methylpyridine, 2,6-lutidine, triethylamine, etc.). 【0097】 In embodiments where polymer block (B) is a hydrocarbon polymer, yet another example of a method for synthesizing a polyfunctional macromonomer (a4) is to prepare a monomer having both a cationic polymerizable functional group and a (meth)acryloyl group, and then randomly copolymerize this monomer with isobutylene to obtain a polyisobutylene polymer having a (meth)acryloyl group as a side chain. 【0098】 In embodiments where the polymer block (B) is a hydrocarbon polymer, 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 Co., Ltd., polybutadiene polymer). 【0099】In the graft copolymer (P), the ratio of polymer block (A) to polymer block (B) can be appropriately set according to the effect to be achieved, but specifically, it is preferable that the ratio of polymer block (A) to the total of polymer block (A) and polymer block (B) is 35 to 70% by weight, and the ratio of polymer block (B) is 30 to 65% by weight. If the ratio of polymer block (B) is 30% by weight or more, the elongation of the cured product can be increased. On the other hand, if the ratio of polymer block (B) is 65% by weight or less, the initial fixation after heating and melting the hot-melt curable composition according to this disclosure can be increased, and the strength of the cured product can be further increased. 【0100】 The proportion of polymer block (A) is preferably 40 to 65% by weight, and the proportion of polymer block (B) is preferably 35 to 60% by weight, with the former being more preferably 45 to 60% by weight and the latter 40 to 55% by weight. 【0101】 Furthermore, from the viewpoint of the effects described above, the content of polymer blocks (B) is preferably 0.05 mol% to 6.0 mol%, more preferably 0.1 mol% to 2.3 mol%, and even more preferably 0.2 mol% to 1.5 mol%, of the total amount of constituent units forming the graft copolymer (P). 【0102】 The average number of polymer blocks (B) per molecule of graft copolymer (P) 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 (P) (g / mol) / (Weight of graft copolymer (P) (g) / (Number of moles of polymer blocks (B))) 【0103】<Block Bonding Configuration> The graft copolymer (P) consists of polymer blocks (A) and polymer blocks (B) bonded in the order A-B-A. However, the graft copolymer (P) is not limited to only A-B-A triblocks, but may also include multiblocks in which blocks (B) and / or blocks (A) are further bonded to the triblock, or A-B diblocks, etc. 【0104】 Graft copolymers (P) can be prepared by free radical polymerization. When prepared by free radical polymerization, some molecules in the graft copolymer (P) may include polymer components in which block (A) and block (B) are not bonded to each other. In this disclosure, graft copolymer (P) is defined as containing such unbonded polymer components and graft copolymer components other than the A-B-A triblock described above. The ratio of graft copolymer components in which block (A) and block (B) are bonded to unbonded polymer components can be determined by known means, such as GPC analysis. 【0105】 In the graft copolymer (P), it is preferable that polymer block (A) and polymer block (B) are linked via ester bonds derived from the (meth)acryloyl group in the polyfunctional macromonomer (a4) (i.e., ester bonds in the general formulas (2) to (4)). 【0106】 The bonding configuration between polymer block (A) and polymer block (B) is not particularly limited, but can be represented by the following general formulas (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 polymer block (A) and B represents polymer block (B). R ３ ~R ５ The same applies to equations (2) and (4) as described above. 【0107】It is preferable that polymer block (A) and polymer block (B) exhibit different glass transition temperatures, and in particular, it is preferable to select the monomer compositions constituting both polymer blocks such that the glass transition temperature of polymer block (A) is higher than that of polymer block (B). According to this embodiment, a reactive silicon group-containing graft copolymer can be easily formed that has low viscosity when heated and melted, good initial fixation after heating and melting, and can achieve high strength after curing. 【0108】 In this case, the glass transition temperature of polymer block (A) is preferably 50°C or higher, and more preferably 70°C or higher. The upper limit is not particularly limited, but for example, it may be 120°C or lower, or even 100°C or lower. Furthermore, the glass transition temperature of polymer block (B) is preferably 0°C or lower, and more preferably -30°C or lower. The lower limit is not particularly limited, but for example, it may be -80°C or higher, or even -60°C or higher. The glass transition temperature can be determined using the following Fox formula: Fox formula: 1 / (Tg(K)) = Σ(Mi / Tgi) (wherein Mi is the weight fraction of monomer i constituting the polymer, and Tgi is the glass transition temperature (K) of the homopolymer of monomer i.) 【0109】 The glass transition temperature (Tg) of homopolymers should be based on the values ​​described in *Polymer Handbook - Fourth Edition* (J. Brandrup et al.). When calculating Tg using Fox's formula, monomers containing reactive silicon groups (a1-2) and chain transfer agents should not be included in the calculation. 【0110】 When polymer block (A) is composed of a hard polymer, i.e., a polymer with a high glass transition temperature, it is preferable that the (meth)acrylic acid ester (a1) of polymer block (A) contains an alkyl methacrylate ester with three or fewer C1 atoms in the alkyl group. 【0111】 When a polymer block (A) is formed using a chain transfer agent (a2) having a mercapto group, the substituents originating from (a2) are -S-R ８It 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. 【0112】 The graft copolymer (P) may have a linear structure in which the ends of polymer block (A) and polymer block (B) are connected, but it is preferable that it includes an H-type structure. Figure 1 shows a conceptual diagram of the H-type structure. In this structure, the two vertical bars represent polymer block (A), and the one horizontal bar represents polymer block (B). Both ends of polymer block (B) are bonded to the non-terminal portions of polymer block (A). At one end of each of the two polymer blocks (A), there is a substituent derived from a chain transfer agent having a mercapto group and a reactive silicon group, namely -S-R ８ -SiR １ ３－ａ X ａ It is bonded. Also, -SiR is present in the non-terminal portion of polymer block (A). １ ３－ａ X ａ These are randomly bonded, which originate from (meth)acrylic acid esters (a1-2) having reactive silicon groups. 【0113】 The H-type structure can be formed by random polymerization of a polyfunctional macromonomer (a4), which has (meth)acryloyl groups at both ends of the polymer molecular chain, with a (meth)acrylic acid ester (a1) and a chain transfer agent (a2) having a mercapto group. 【0114】<Molecular Weight of Graft Copolymer (P)> The number average molecular weight of the graft copolymer (P) is not particularly limited, but is preferably 500 to 50,000 in polystyrene equivalent molecular weight as measured by GPC, more preferably 500 to 30,000, and particularly preferably 1,000 to 10,000. In particular, since a low viscosity graft copolymer can be obtained, the number average molecular weight of the graft copolymer (P) is preferably 7,000 or less, more preferably 5,000 or less, and even more preferably 4,000 or less. 【0115】 The weight-average molecular weight of the graft copolymer (P) is not particularly limited, but is preferably 500 to 80,000 in polystyrene equivalent molecular weight as measured by GPC, more preferably 3,000 to 70,000, and particularly preferably 5,000 to 65,000. In particular, the weight-average molecular weight of the graft copolymer (P) is preferably 40,000 or less, as this yields a cured product with low viscosity and high strength. 【0116】 The molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of the graft copolymer (P) is not particularly limited, but from the viewpoint of making the graft copolymer low viscosity, it is preferably 3.0 to 11.0 and more preferably 5.0 to 10.0. 【0117】 The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the graft copolymer (P) are measured in polystyrene equivalents by gel permeation chromatography (GPC). The detailed measurement method is described in the examples. As mentioned above, the graft copolymer (P) may contain polymer components in which block (A) and block (B) are not bonded to each other, but the number-average molecular weight, weight-average molecular weight, and molecular weight distribution of the graft copolymer (P) are values ​​measured for the entire graft copolymer (P), including such polymer components. 【0118】<Method for Producing Graft Copolymer (P)> Graft copolymer (P) 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 (a4). The polymerization method is not particularly limited, but may be a general free radical polymerization. According to this disclosure, even though it is free radical polymerization, polymerization can be controlled, graft copolymer (P) can be produced, and its molecular weight distribution can be made relatively narrow. 【0119】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; Peroxy dicarbonates such as dichlorohexyl 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 quyl perneodecanoate; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide. Examples of polymerization initiators include dialkyl peroxides such as di-tert-butyl peroxide, diqumyl peroxide, tert-butylqumyl 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. 【0120】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. 【0121】 As described above, the graft copolymer (P) can be made to have reactive silicon groups by using (meth)acrylic acid esters (a1-2) having reactive silicon groups, or by using a chain transfer agent (a2) having reactive silicon groups in addition to mercapto groups. Both methods may be used in combination. By using (meth)acrylic acid esters (a1-2) having reactive silicon groups, reactive silicon groups can be randomly introduced into the side chains of polymer block (A). Alternatively, by using a chain transfer agent (a2) having reactive silicon groups in addition to mercapto groups, reactive silicon groups can be introduced into the terminals of polymer block (A). 【0122】However, the following methods can also be used in combination to further introduce reactive silicon groups into the graft copolymer (P): (i) A monomer having a reactive functional group (V group) copolymerizes with a (meth)acrylic acid ester (a1), and then reacts the resulting copolymer with a compound having a functional group that reacts with the V group and a reactive silicon group. Specifically, examples include copolymerizing 2-hydroxyethyl acrylate and then reacting it with an isocyanate silane compound having a reactive silicon group, or copolymerizing glycidyl acrylate and then reacting it with an aminosilane compound having a reactive silicon group. (ii) A method of 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 accept the introduction of functional groups at the polymer ends, and reactive silicon groups can be introduced at the polymer ends by modifying them. 【0123】 Examples of compounds having a functional group that reacts with the V group and a reactive silicon group used in method (i) include 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. 【0124】 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. 【0125】 <<Reactive Silicon Group-Containing Compound (C)>> The hot-melt curable composition according to this disclosure contains a reactive silicon group-containing compound (C) that does not contain an amino group, in addition to the graft copolymer (P). The reactive silicon group-containing compound (C) is a compound that can react with water and functions as a dehydrating agent. By incorporating this compound, the storage stability of the hot-melt curable composition according to this disclosure can be improved. 【0126】 The reactive silicon-containing compound (C) is a compound that does not contain an amino group, and therefore, aminosilane compounds, which are commonly used as adhesion promoters, are excluded. Because it does not contain an amino group, it can function as a dehydrating agent. 【0127】 The reactive silicon group-containing compound (C) has a boiling point of 150°C or higher at atmospheric pressure. If a reactive silicon group-containing compound with a boiling point below 150°C is incorporated, the compound may volatilize when the graft copolymer (P) is heated until it melts during the preparation or use of the hot-melt curable composition, potentially creating a hazard at the work site. Therefore, in the hot-melt curable composition according to this disclosure, the reactive silicon group-containing compound is one that does not easily volatilize when heated, specifically a compound with a boiling point of 150°C or higher at atmospheric pressure. 【0128】 Furthermore, vinyltrimethoxysilane is widely used as a dehydrating agent for organic polymers containing reactive silicon groups, but the boiling point of this compound at atmospheric pressure is 123°C. 【0129】A high boiling point is desirable for the reactive silicon group-containing compound (C), preferably 180°C or higher, and more preferably 200°C or higher under atmospheric pressure. Furthermore, there is no particular upper limit to the boiling point. Compounds whose boiling point is too high to measure under atmospheric pressure are also considered to be compounds that satisfy the requirement of a boiling point of 150°C or higher under atmospheric pressure. While there is no particular upper limit to the boiling point of compound (C) under atmospheric pressure, it may be, for example, 350°C or lower, 300°C or lower, or 250°C or lower. 【0130】 The reactive silicon group-containing compound (C) is preferably a silane compound having reactive silicon represented by the general formula (1) described for the graft copolymer (P), or a condensate thereof. 【0131】 The molecular weight of the silane compound having reactive silicon represented by general formula (1) is not particularly limited, but may be, for example, around 100 to 1,500. The lower limit of the molecular weight may be 150 or more. The upper limit may be 1,000 or less, or 500 or less. 【0132】 The condensate of the silane compound refers to an oligomer, which is a partially hydrolyzed condensate of a silane compound, formed by the condensation of silane compounds through the formation of siloxane bonds. 【0133】 The reactive silicon group-containing compound (C) is preferably a silane compound or condensate thereof having reactive silicon, where X in general formula (1) represents a hydrolyzable group. The hydrolyzable group is preferably an alkoxy group. The number of carbon atoms in the alkoxy group is not particularly limited, but may be 1 to 3, preferably 1 or 2, and particularly preferably 1. In general formula (1), a preferably represents 3. 【0134】 In one preferred embodiment, the reactive silicon group-containing compound (C) may be a condensate of a silane compound having a vinyl group and a reactive silicon group. Among these, a condensate of a trialkoxysilane having a vinyl group is preferred, and a condensate of a vinyltrimethoxysilane is more preferred. 【0135】In another preferred embodiment, the reactive silicon group-containing compound (C) may be a silane compound having a nitrile group and a reactive silicon group. Among these, trialkoxysilane having a nitrile group is preferred, and trimethoxysilane having a nitrile group is more preferred. The nitrile group may be directly bonded to the silicon atom, but it is preferable that it is bonded to a hydrocarbon group bonded to the silicon atom. 【0136】 The hydrocarbon group to which the nitrile group is bonded is not particularly limited and may be an alkyl group, an aryl group, or an aralkyl group, but an alkyl group is preferred. The number of carbon atoms in the hydrocarbon group (excluding the carbon atoms of the nitrile group) is not particularly limited and may be, for example, 1 to 12, 1 to 6, 1 to 3, or 2 to 3. 【0137】 In another preferred embodiment, the reactive silicon group-containing compound (C) may be a silane compound having an alkyl group with 6 or more carbon atoms and a reactive silicon group. Among these, alkyltrialkoxysilanes having an alkyl group with 6 or more carbon atoms are preferred, and alkyltrimethoxysilanes having an alkyl group with 6 or more carbon atoms are more preferred. 【0138】 The alkyl group having 6 or more carbon atoms may be directly bonded to a silicon atom. The number of carbon atoms in the alkyl group is preferably 6 to 20, more preferably 8 to 18, and even more preferably 10 to 16. 【0139】 Only one type of reactive silicon group-containing compound (C) may be used, or two or more types may be used in combination. 【0140】 The amount of reactive silicon group-containing compound (C) can be appropriately designed according to the desired storage stability, but is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 10 parts by weight, and even more preferably 0.5 to 5 parts by weight, per 100 parts by weight of graft copolymer (P). 【0141】<<Silanol Condensation Catalyst>> The hot-melt curable composition according to this disclosure preferably contains a silanol condensation catalyst (also called a curing catalyst) to promote the condensation reaction of the reactive silicon groups of the graft copolymer (P). Examples of silanol condensation catalysts include organotin compounds, metal carboxylic acid salts, amine compounds, carboxylic acids, and alkoxy metals. 【0142】 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. 【0143】 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. 【0144】 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. 【0145】 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. 【0146】 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). 【0147】 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 (P), from the viewpoint of promoting the condensation reaction of reactive silicon groups. 【0148】 <<Other Additives>> In addition to the graft copolymer (P), reactive silicon group-containing compound (C), and silanol condensation catalyst, the hot-melt curable composition according to this disclosure may also contain plasticizers, fillers, adhesion promoters, rheology control agents, antioxidants, light stabilizers, ultraviolet absorbers, and other resins as additives. 【0149】 Furthermore, various additives may be added to the hot-melt curable composition according to this disclosure 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, curing modifiers, radical inhibitors, metal deactivators, ozone degradation inhibitors, phosphorus-based peroxide decomposers, lubricants, pigments, antifungal agents, flame retardants, and foaming agents. 【0150】 <Plasticizers> Plasticizers can be added to hot-melt curable compositions. The addition of plasticizers can reduce the viscosity of the curable composition, making it easier to handle. 【0151】The plasticizer is not particularly limited, but examples 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 fats such as dioctyl adipicate, 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 epoxybenzyl stearate; and alkyl sulfonic acid esters. 【0152】 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-based 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. Only one type of plasticizer may be used, or two or more types may be used in combination. 【0153】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 (P). 【0154】 <Fillers> Fillers can be added to hot-melt curable compositions. The strength of the cured product can be improved by adding fillers. 【0155】 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. 【0156】 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 (P). 【0157】 <Adhesion-improving agents> Adhesion-improving agents may be added to hot-melt curable compositions. As adhesion-improving agents, silane coupling agents or reaction products of silane coupling agents may be added. 【0158】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. 【0159】 The amount of adhesion-improving agent 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 (P). 【0160】 <Rheology Control Agent> Rheology control agents may be added to hot-melt curable compositions as needed to prevent sagging and improve workability. 【0161】 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. 【0162】 The amount of rheology control agent added is preferably 0.1 to 20 parts by weight per 100 parts by weight of graft copolymer (P). 【0163】 <Antioxidants> Antioxidants (anti-aging agents) can be used in hot-melt curable compositions. 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 (P). 【0164】 <Light stabilizers> Light stabilizers can be used in hot-melt curable compositions. 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 (P). 【0165】 <UV Absorbers> UV absorbers can be used in hot-melt curable compositions. 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, including commercially available products such as Chinuvin P, Chinuvin 213, Chinuvin 234, Chinuvin 326, Chinuvin 327, Chinuvin 328, Chinuvin 329, and Chinuvin 571 (all manufactured by BASF). The amount of UV absorber to be 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 (P). 【0166】The hot-melt curable composition according to this disclosure can be prepared as a one-component type that hardens after application by moisture in the air, after all components have 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. 【0167】 Furthermore, the hot-melt curable composition according to this disclosure is composed of a main component containing a graft copolymer (P) and a curing agent containing components such as a silanol condensation catalyst, filler, plasticizer, and water, and can be prepared as a two-component type in which the main component and curing agent are mixed before use. 【0168】 There are no particular limitations on the method for preparing the hot-melt curable composition relating to this disclosure. 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. 【0169】 The hot-melt curable composition according to this disclosure 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 with 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. 【0170】The cured product obtained by curing the hot-melt curable composition according to this disclosure has good adhesion to various substrates, and therefore the curable composition can be used as an adhesive, sealant, or tack. In particular, the hot-melt curable composition according to this disclosure 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, especially a hot-melt adhesive. 【0171】 The hot-melt curable composition according to this disclosure is preferably heated to a high temperature to reduce its viscosity in order to ensure workability when applied to a substrate. The temperature is preferably around 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 conventionally known methods can be used. 【0172】 The hot-melt curable composition according to this disclosure can exhibit desired physical properties by performing a long curing (curing) process after joining 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 time of 24 hours to 1 week. 【0173】 The hot-melt curable composition according to this disclosure can be used as a reactive hot-melt adhesive. This hot-melt 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, and aluminum-composite. 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. 【0174】More specifically, the hot-melt curable composition relating to this disclosure 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 machine parts. 【0175】 The following sections list preferred embodiments of this disclosure, but the present invention is not limited to these sections. [Section 1] General formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １A hot-melt curable composition comprising: a (meth)acrylic acid ester polymer block (A) having a reactive silicon group represented by ) and a polymer block (B) selected from the group consisting of (meth)acrylic acid ester polymer blocks, polyoxyalkylene polymer blocks, and hydrocarbon polymer blocks, bonded in the order A-B-A; and a reactive silicon group-containing compound (C) having a boiling point of 150°C or higher at atmospheric pressure and lacking an amino group. [Item 2] The hot-melt curable composition according to Item 1, wherein the reactive silicon group-containing compound (C) is a condensate of a silane compound having a vinyl group and a reactive silicon group. [Item 3] The hot-melt curable composition according to Item 1 or 2, wherein the reactive silicon group-containing compound (C) is a silane compound having a nitrile group and a reactive silicon group. [Item 4] The hot-melt curable composition according to any one of Items 1 to 3, wherein the reactive silicon group-containing compound (C) is a silane compound having an alkyl group with 6 or more carbon atoms and a reactive silicon group. [Item 5] The hot-melt curable composition according to any one of Items 1 to 4, wherein 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, and the sulfur atom concentration derived from the chain transfer agent (a2) is 4,500 to 10,000 ppm in the graft copolymer (P). [Item 6] The hot-melt curable composition according to any one of Items 1 to 5, wherein the content of alkyl (meth)acrylic acid esters with 7 or more carbon atoms in the alkyl group contained in the polymer block (A) is 0% by weight or more and 10% by weight or less in the graft copolymer (P), and the content of alkyl (meth)acrylic acid esters with 3 or fewer carbon atoms in the alkyl group contained in the polymer block (A) is 25% by weight or more in the graft copolymer (P). [Item 7] The hot-melt curable composition according to any one of Items 1 to 5, wherein the content of alkyl (meth)acrylate esters with 4 or more C atoms in the polymer block (A) is 10% by weight or more in the graft copolymer (P).[Item 8] A hot-melt curable composition according to any one of Items 1 to 7, wherein 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, relative to the total of polymer block (A) and polymer block (B). [Item 9] A hot-melt curable composition according to any one of Items 1 to 8, wherein the reactive silicon group equivalent of the graft copolymer (P) is 0.15 to 0.5 mmol / g. [Item 10] A hot-melt curable composition according to any one of Items 1 to 9, wherein the content of the reactive silicon group-containing compound (C) is 0.1 to 20 parts by weight per 100 parts by weight of the graft copolymer (P). [Item 11] A hot-melt adhesive comprising the hot-melt curable composition according to any one of Items 1 to 10. 【0176】 The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the present invention. 【0177】 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°C 【0178】 (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 (P) and the amount of chain transfer agent (a2) having a mercapto group. 【0179】(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, 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 in a nitrogen atmosphere at 90°C for 1 hour 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 21,100, and a weight average molecular weight of 24,930. 【0180】 (Synthesis Example 2) 0.42 parts by weight of cuprous bromide and 20.0 parts by weight of butyl acrylate were added to a deoxygenated reactor and heated and stirred. 8.8 parts by weight of acetonitrile as the polymerization solvent and 3.1 parts by weight of diethyl 2,5-dibromoadipate as an initiator were added and mixed. When the temperature of the mixture was adjusted to approximately 80°C, pentamethyldiethylenetriamine (hereinafter abbreviated as triamine) was added to start the polymerization reaction. Next, 80.0 parts by weight of butyl acrylate were added sequentially to proceed with the polymerization reaction. Triamine was added as needed during polymerization to adjust the polymerization rate. The total amount of triamine used during polymerization was 0.15 parts by weight. When the monomer conversion rate (polymerization reaction rate) reached approximately 95% or higher, volatile components were removed by defloration under reduced pressure to obtain a polymer concentrate. The concentrate was diluted with toluene, and a filter aid, an adsorbent (Kyoward 700SEN: manufactured by Kyowa Chemical Co., Ltd.), and hydrotalcite (Kyoward 500SH: manufactured by Kyowa Chemical Co., Ltd.) were added. After heating and stirring to approximately 80-100°C, the solid components were filtered off. The filtrate was concentrated under reduced pressure to obtain a crude polymer product. 【0181】Crude polymer, 3.8 parts by weight of potassium acrylate, 100 ppm of 4-hydroxy-TEMPO, and 100 parts by weight of dimethylacetamide as a solvent were added and reacted at 70°C for 3 hours. After the solvent was removed by vacuum distillation, a polymer concentrate was obtained. The concentrate was diluted with toluene, and the solid components were filtered off. The filtrate was concentrated under vacuum to obtain a (meth)acrylic acid ester polymer (b-2) having acryloyl groups at both ends (i.e., two acryloyl groups in one polymer molecule), a number-average molecular weight of 10,730 (GPC molecular weight), and a molecular weight distribution (Mw / Mn) of 1.19. 【0182】 (Synthesis Example 3) 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 43.9 parts by weight of methyl methacrylate, 0.5 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 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 graft copolymer (P-1) with a number average molecular weight of 3,410 (GPC molecular weight). The solution has a polyfunctional macromonomer equivalent of 0.023 mmol / g, a reactive silicon group equivalent of 0.32 mmol / g, and a sulfur atom concentration of 5,217 ppm. 【0183】(Synthesis Example 4) 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 45.9 parts by weight of methyl methacrylate, 0.5 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (b-2) prepared in Synthesis Example 2, 2.3 parts by weight of 3-methacryloxypropyl dimethoxymethylsilane, 2.9 parts by weight of 3-mercaptopropyl dimethoxymethylsilane, 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. Furthermore, 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 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 graft copolymer (P-2) with a number average molecular weight of 3,950 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.045 mmol / g, the reactive silicon group equivalent was 0.26 mmol / g, and the sulfur atom concentration was 5,147 ppm. 【0184】(Synthesis Example 5) 44.4 parts by weight of toluene was placed in a four-necked flask equipped with a stirrer and heated 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-methacryloxypropyl dimethoxymethylsilane, 48.0 parts by weight of isobornyl acrylate, 4.0 parts by weight of 3-mercaptopropyl dimethoxymethylsilane, 35.0 parts by weight of a polyisobutylene-based macromonomer (having an average of 2 acryloyl groups per molecule, with a number average molecular weight of 14,650 and a molecular weight distribution of 1.16, trade 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 over 3 hours. Furthermore, a mixed solution of 0.35 parts by weight of 2,2'-azobis(2-methylbutyronitrile) dissolved in 10.9 parts by weight of toluene was added, and polymerization was carried out at 110°C for 2 hours to obtain a toluene solution (60% solids) of a reactive silicon group-containing graft copolymer (P-3) with a number average molecular weight of 3,260 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.028 mmol / g, the reactive silicon group equivalent was 0.35 mmol / g, and the sulfur atom concentration was 7,099 ppm. 【0185】 (Example 1) The butyl acetate solution of the graft copolymer (P-1) obtained in Synthesis Example 3 was heated and deflated to obtain a solid graft copolymer (P-1) at room temperature. 100 parts by weight of the graft copolymer (P-1) was heated and melted at 140°C, and 1 part by weight of KBM-3103C (decyltrimethoxysilane, boiling point at 1.3 kPa pressure: 132°C (boiling point at atmospheric pressure: 150°C or higher), manufactured by Shin-Etsu Chemical Co., Ltd.), 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, and the mixture was filled into a 30 cc syringe. 【0186】(Melting Viscosity) A parallel disc plate with a diameter of 20 mm was used as a jig, with a gap set to 0.5 mm, and the viscosity (initial viscosity) of the compound filled in a syringe was measured at 120°C. The results are shown in Table 1. A rheometer (DHR-2) manufactured by TA Instruments was used as the apparatus. Subsequently, a 30 cc syringe filled with the compound was stored at 120°C for 6 hours, and the viscosity was measured again using the same method to obtain the viscosity after storage. The rate of change in melting viscosity was calculated from the initial viscosity and the viscosity after storage. The results are shown in Table 1. 【0187】 (Complex Modulus of Elasticity) The compound, filled into a syringe, was measured for dynamic viscoelasticity while being cooled from 150°C to 10°C using a parallel disc plate with a diameter of 20 mm as a jig, with a gap set to 0.5 mm. The complex modulus of elasticity was recorded at 23°C. The results are shown in Table 1. A rheometer (DHR-2) manufactured by TA Instruments was used. 【0188】 (Volatility) When the graft copolymer was heated and melted at 140°C and the components were mixed, we checked whether volatility was observed. The results are shown in Table 1. 【0189】 (Example 2) The formulation was prepared in the same manner as in Example 1, except that Dynasilan 6490 (a vinyltrimethoxysilane condensate, boiling point at atmospheric pressure: 220°C, manufactured by Evonik) was used instead of KBM-3103C, and the same evaluation was performed. 【0190】 (Example 3) The formulation was prepared in the same manner as in Example 1, except that Silquest CNM (2-cyanoethyltrimethoxysilane, boiling point at atmospheric pressure: 213°C, manufactured by Momentive) was used instead of KBM-3103C, and the same evaluation was performed. 【0191】(Example 4) The butyl acetate solution of the graft copolymer (P-2) obtained in Synthesis Example 4 was heated and defoliated to obtain a solid graft copolymer (P-2) at room temperature. The formulation was prepared in the same manner as in Example 3, except that graft copolymer (P-2) was used instead of graft copolymer (P-1), and 1 part by weight of U-130 (dibutyltin oxylaurate, manufactured by Nitto Chemical Co., Ltd.) was used instead of U-810, and the same evaluation was performed. 【0192】 (Example 5) The toluene solution of the graft copolymer (P-3) obtained in Synthesis Example 5 was heated and deflated to obtain a solid graft copolymer (P-3) at room temperature. The formulation was prepared in the same manner as in Example 1, except that graft copolymer (P-3) was used instead of graft copolymer (P-1), and the same evaluation was performed. 【0193】 (Comparative Example 1) The formulation was prepared in the same manner as in Example 1, except that KBM-3103C was not used. However, the formulation gelled after being stored at 120°C for 6 hours, making evaluation impossible. 【0194】 (Comparative Example 2) An attempt was made to prepare the formulation in the same manner as in Example 1, except that A-171 (vinyltrimethoxysilane, boiling point at atmospheric pressure: 123°C, manufactured by Momentive) was used instead of KBM-3103C. However, volatility was observed when the graft copolymer (P-1) was heated and melted at 140°C to mix the components, which posed a risk and prevented the various evaluations from being carried out. 【0195】 【0196】 Table 1 shows that the hot-melt curable compositions obtained in Examples 1 to 5 showed no volatility during preparation and exhibited small changes in melt viscosity during storage, indicating good storage stability. Furthermore, in all examples, the values ​​of the complex modulus measured at 23°C indicate that each composition was in a solid state at room temperature. 【0197】On the other hand, in Comparative Example 1, which did not contain reactive silicon-containing compound (C), the composition gelled during storage, indicating insufficient storage stability. Furthermore, in Comparative Example 2, which used a reactive silicon-containing compound with a boiling point of less than 150°C instead of reactive silicon-containing compound (C), volatility was observed, indicating that it was unsuitable for use as a hot-melt curable composition.

Claims

1. General formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １ A hot-melt curable composition containing a (meth)acrylic acid ester polymer block (A) having a reactive silicon group represented by (meth)acrylic acid ester polymer block, and a polymer block (B) selected from the group consisting of (meth)acrylic acid ester polymer blocks, polyoxyalkylene polymer blocks, and hydrocarbon polymer blocks, bonded in the order A-B-A, and a reactive silicon group-containing compound (C) having a boiling point of 150°C or higher at atmospheric pressure and lacking an amino group.

2. The hot-melt curable composition according to claim 1, wherein the reactive silicon group-containing compound (C) is a condensate of a silane compound having a vinyl group and a reactive silicon group.

3. The hot-melt curable composition according to claim 1, wherein the reactive silicon group-containing compound (C) is a silane compound having a nitrile group and a reactive silicon group.

4. The hot-melt curable composition according to claim 1, wherein the reactive silicon group-containing compound (C) is a silane compound having an alkyl group with 6 or more carbon atoms and a reactive silicon group.

5. The hot-melt curable composition according to claim 1, wherein the polymer block (A) comprises 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, and the sulfur atom concentration derived from the chain transfer agent (a2) is 4,500 to 10,000 ppm in the graft copolymer (P).

6. The hot-melt curable composition according to claim 1, wherein the content of alkyl (meth)acrylate esters with 7 or more C atoms in the polymer block (A) is 0% by weight or more and 10% by weight or less in the graft copolymer (P), and the content of alkyl (meth)acrylate esters with 3 or fewer C atoms in the polymer block (A) is 25% by weight or more in the graft copolymer (P).

7. The hot-melt curable composition according to claim 1, wherein the amount of alkyl (meth)acrylate ester containing four or more C atoms in the polymer block (A) is 10% by weight or more in the graft copolymer (P).

8. The hot-melt curable composition according to claim 1, wherein 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, relative to the total of polymer block (A) and polymer block (B).

9. The hot-melt curable composition according to claim 1, wherein the reactive silicon group equivalent of the graft copolymer (P) is 0.15 to 0.5 mmol / g.

10. The hot-melt type curable composition according to claim 1, wherein the content of the reactive silicon group-containing compound (C) is 0.1 to 20 parts by weight per 100 parts by weight of the graft copolymer (P).

11. A hot-melt adhesive comprising the hot-melt curable composition according to any one of claims 1 to 10.

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