Graft copolymer and hot-melt adhesive

Abstract

Provided is a graft copolymer comprising a (meth)acrylate ester-based polymer block (A) having a reactive silicon group represented by the formula: -SiR1 3-aXa, and a (meth)acrylate ester-based polymer block (B) having a number average molecular weight of 7,000 or more. The (meth)acrylate ester-based polymer block (A) and the (meth)acrylate ester-based polymer block (B) are bonded in the order of A-B-A. A reactive silicon group equivalent in the graft copolymer is 0.15 mmol / g or more. A content of an alkyl (meth)acrylate ester contained in the polymer block (A), in which the carbon number of the alkyl is 7 or more, is 0-10 wt% in the graft copolymer. A content of an alkyl (meth)acrylate ester contained in the polymer block (A), in which the carbon number of the alkyl is 3 or less, is 25 wt% or more in the graft copolymer.

Description

Graft copolymers and hot-melt adhesives

[0001] The present invention relates to a graft copolymer having a reactive silicon group, and a hot-melt adhesive containing the polymer.

[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] One known organic polymer having such reactive silicon groups is a (meth)acrylic acid ester copolymer. Patent Document 1 discloses a (meth)acrylic acid ester copolymer having reactive silicon groups, comprising a (meth)acrylic acid ester, a (meth)acrylic acid ester polymer having one or more (meth)acryloyl groups in the molecule, and a chain transfer agent having a mercapto group. This copolymer is a graft copolymer containing at least two types of (meth)acrylic acid ester polymer blocks.

[0004] Furthermore, Patent Documents 2 and 3 disclose the use of such (meth)acrylic acid ester copolymers as the main resin component of a hot-melt curable composition.

[0005] International Publication No. 2022 / 009933, Japanese Patent Publication No. 2023-100363, International Publication No. 2023 / 132324

[0006] Hot-melt adhesives are solid at room temperature, but become fluid when heated and melted, allowing them to be applied to substrates. Hot-melt adhesives are required to have (1) sufficiently low viscosity when heated and melted, resulting in good applicability, (2) good initial fixation immediately after application to the substrate and bonding the substrates together, and (3) high strength of the cured product.

[0007] Patent documents 1 to 3 disclose graft copolymers containing at least two types of (meth)acrylic acid ester polymer blocks, but it was difficult to obtain these graft copolymers to possess the physical properties described above.

[0008] In view of the above situation, the present invention aims to provide a reactive silicon group-containing graft copolymer comprising at least two types of (meth)acrylic acid ester polymer blocks, which has low viscosity when heated and melted, good initial fixation after heating and melting, and can achieve high strength after curing.

[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 using a reactive silicon group-containing graft copolymer containing at least two types of (meth)acrylic acid ester polymer blocks, bonding each block in a specific order, and setting the reactive silicon group equivalent of the graft copolymer, as well as the content of alkyl (meth)acrylate esters with 7 or more C atoms and alkyl (meth)acrylate esters with 3 or fewer C atoms in polymer block (A), to specific ranges, 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) represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. X represents a hydroxyl group or a hydrolyzable group. a represents 2 or 3. ) The present invention relates to a graft copolymer in which a (meth)acrylic acid ester polymer block (A) having a reactive silicon group represented by and a (meth)acrylic acid ester polymer block (B) having a number average molecular weight of 7,000 or more are bonded in the order A-B-A, wherein the polymer block (A) and the polymer block (B) have different glass transition temperatures, the reactive silicon group equivalent of the graft copolymer is 0.15 mmol / g or more, the content of alkyl (meth)acrylic acid ester 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, and the content of alkyl (meth)acrylic acid ester 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. The present invention also relates to a hot melt adhesive containing the graft copolymer.

[0011] According to the present invention, it is possible to provide a reactive silicon group-containing graft copolymer comprising at least two types of (meth)acrylic acid ester polymer blocks, which has low viscosity when heated and melted, good initial fixation after heating and melting, and can achieve high strength after curing. A graft copolymer according to a preferred embodiment of the present invention is solid at room temperature and can be used as a main resin component of a hot-melt adhesive.

[0012] Conceptual diagram of an H-type structure that may be included in the graft copolymer relating to this disclosure

[0013] 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.

[0014] The graft copolymer according to this embodiment is formed by bonding a (meth)acrylate polymer block (A) and a (meth)acrylate polymer block (B). The graft copolymer has a reactive silicon group, and the reactive silicon group is bonded to the polymer block (A). The polymer block (A) and the polymer block (B) have different compositions of constituent monomers, and as a result, exhibit different glass transition temperatures. In the present application, "(meth)acryl" represents "acryl and / or methacryl".

[0015] <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.)

[0016] 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 a methyl group and a methoxymethyl group.

[0017] 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, and an alkenyloxy group. Among these, an alkoxy group is more preferable, and a methoxy group and an ethoxy group are particularly preferable because of their mild hydrolyzability and easy handling.

[0018] 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.

[0019] The reactive silicon group equivalent of the graft copolymer according to this embodiment is 0.15 mmol / g or more. This enhances the initial fixation after heating and melting the graft copolymer, 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.

[0020] The reactive silicon group equivalent of a graft copolymer is calculated by dividing the total silicon group equivalent of the reactive silicon group-containing components constituting the graft copolymer by the total weight of the components constituting the graft copolymer. Specifically, it can be calculated by adding the silicon group equivalents of the (meth)acrylic acid esters (a1-2) having reactive silicon groups and the silicon group equivalents of the chain transfer agent (a2) having reactive silicon groups, and then dividing this by the total weight of the monomers and chain transfer agent constituting the graft copolymer.

[0021] <(meth)acrylic acid ester polymer block (A)> Polymer block (A) is a polymer block that contains at least one constituent unit derived from (meth)acrylic acid ester (a1).

[0022] <(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) that does not have a reactive silicon group, alkyl (meth)acrylic acid esters are preferred.

[0023] As the (meth)acrylic acid ester (a1-1) that does not have a reactive silicon group, an alkyl (meth)acrylic acid ester with 7 or more C12 atoms in the alkyl group may be used or not, but its content should be set to a range of 0% to 10% by weight in the graft copolymer. If the amount of alkyl (meth)acrylic acid ester having a long-chain alkyl group is increased, it becomes difficult to achieve sufficient initial fixation and high strength after curing. By reducing the amount used, the initial fixation after heating and melting the graft copolymer can be improved, and a high-strength cured product can be obtained. The upper limit of the content is preferably 8% by weight or less, more preferably 7% by weight or less, even more preferably 5% by weight or less, and particularly preferably 3% by weight or less. It may also be 1% by weight or less, or 0% by weight. Furthermore, the upper limit of the number of C12 atoms in the alkyl group is not particularly limited, but may be 20 or less, 15 or less, or 12 or less.

[0024] The (meth)acrylic acid ester (a1-1) that does not have a reactive silicon group contains at least an alkyl (meth)acrylic acid ester with three or fewer C1 atoms in the alkyl group, and the content of this monomer is set to 25% by weight or more in the graft copolymer according to this embodiment. This makes it possible to improve the initial fixation after heating and melting the graft copolymer and to obtain a high-strength cured product. Preferably it is 30% by weight or more, more preferably 35% by weight or more, and even more preferably 40% by weight or more.

[0025] On the other hand, from the viewpoint of lowering the viscosity of the graft copolymer when heated and melted, the upper limit of the monomer content in the graft copolymer according to this embodiment is preferably 60% by weight or less, more preferably 50% by weight or less, and particularly preferably 45% by weight or less.

[0026] As for alkyl methacrylate esters with three or fewer C12 atoms, alkyl methacrylate esters with three or fewer C12 atoms are preferred from the viewpoint of improving initial fixation and obtaining a high-strength cured product, and methyl methacrylate is particularly preferred.

[0027] As the (meth)acrylic acid ester (a1-1) that does not have a reactive silicon group, butyl acrylate may be used or not, but its content is preferably 0% to 8% by weight in the graft copolymer, as this can result in better 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.

[0028] 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).

[0029] 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.

[0030] 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.

[0031] The content of the (meth)acrylate (a1) in the polymer block (A) is preferably 30% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, particularly preferably 60% by weight or more, and particularly preferably 70% by weight or more, from the viewpoint of imparting good physical properties to the cured product, based on the total amount of the constituent units forming the polymer block (A). The upper limit is preferably 100% by weight or less, and more preferably 95% by weight or less.

[0032] <Chain transfer agent (a2) having a mercapto group> The polymer block (A) preferably contains a structural unit derived from a chain transfer agent (a2) having a mercapto group. By using the chain transfer agent (a2) having a mercapto group, the molecular weight of the polymer block (A) can be controlled. In addition, the molecular weight distribution of the graft copolymer can be made relatively narrow, and gelation during the synthesis of the graft copolymer can be suppressed. Further, it becomes possible to preferentially synthesize a polymer molecule in which one polymer block (B) is introduced into one molecule of the graft copolymer.

[0033] The chain transfer agent (a2) having a mercapto group may not have a reactive silicon group, but preferably has a reactive silicon group. The reactive silicon group is the reactive silicon group represented by the above general formula (1). By the chain transfer agent (a2) having a mercapto group having a reactive silicon group, a reactive silicon group can be introduced to the molecular chain end of the polymer block (A).

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

[0035] The content of the chain transfer agent (a2) having a mercapto group is preferably 1% by weight or more and 10% by weight or less of the total amount of constituent units forming the 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.

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

[0037] 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.

[0038] 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 the graft copolymer may contain sulfur atoms.

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

[0040] The aforementioned sulfur atom concentration is a value that reflects the proportion of chain transfer agent used in the graft copolymer. When the sulfur atom concentration is 4,000 ppm or higher, excessive molecular weight increase of polymer block (A) is suppressed, and as a result, the viscosity of the graft copolymer when heated and melted can be further reduced. Furthermore, when the sulfur atom concentration is 10,000 ppm or lower, the initial fixation is improved.

[0041] 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.

[0042] The method for measuring the sulfur atom concentration is not particularly limited. It can be measured by known elemental analysis methods such as organic elemental analysis and X-ray fluorescence analysis. Alternatively, the sulfur atom concentration may be a theoretical value calculated from the total amount of components used in the production of the graft copolymer and the amount of the chain transfer agent (a2) having a mercapto group.

[0043] 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.

[0044] To obtain a cured product with high strength, it is preferable to introduce reactive silicon groups by both conditions 1 and 2. Specifically, the reactive silicon group equivalent 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.

[0045] 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.

[0046] 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 exhibited by the graft copolymer described above.

[0047] 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.

[0048] 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.

[0049] <(meth)acrylic acid ester polymer block (B)> As monomers constituting the main chain skeleton of polymer block (B), (meth)acrylic monomers can be used. 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. In addition, (meth)acrylic acid esters having a reactive silicon group may be used in polymer block (B), but it is preferable not to use them.

[0050] 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.

[0051] 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.

[0052] The polymer block (B) is preferably composed of a soft polymer, i.e., a polymer with a low glass transition temperature. Specifically, the polymer block (B) is preferably 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.

[0053] 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.

[0054] 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.

[0055] The polymer block (B) may have reactive silicon groups represented by the general formula (1) bonded to it, but it is preferable that it does not have reactive silicon groups bonded to it. That is, it is preferable not to use (meth)acrylic acid esters having reactive silicon groups as monomers to form the polymer block (B).

[0056] The number-average molecular weight of polymer block (B) is 7,000 or more. This allows the cured product obtained from the graft copolymer to exhibit high strength. The number-average molecular weight is preferably 8,000 or more, 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.

[0057] 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.

[0058] 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.

[0059] Polymer block (B) can be introduced into the graft copolymer by using a (meth)acrylic acid ester polymer (a4) having an average of more than one (meth)acryloyl group in its molecule. Polymer (a4) can copolymerize with (meth)acrylic acid ester (a1) because it has (meth)acryloyl groups. Moreover, because polymer (a4) has more than one (meth)acryloyl group in each molecule, it can function as a so-called polyfunctional macromonomer. Hereinafter, polymer (a4) will also be referred to as "polyfunctional macromonomer (a4)".

[0060] The (meth)acryloyl group of the polyfunctional macromonomer (a4) is not particularly limited, but can be represented by the following general formula (4): CH ２ = C(R ７ )-C(=O)-O-B (4) In each formula, R ７ represents a hydrogen or methyl group. B represents the main chain skeleton of the polyfunctional macromonomer (a4), i.e., the (meth)acrylic acid ester polymer skeleton.

[0061] The polyfunctional macromonomer (a4) has an average of more than one (meth)acryloyl group per molecule. The average number of (meth)acryloyl groups per molecule of the polyfunctional macromonomer (a4) is preferably 1.1 to 5, more preferably 1.3 to 4, even more preferably 1.6 to 2.5, and particularly preferably 1.8 to 2.0. The polyfunctional macromonomer (a4) may have only acryloyl groups, only methacryloyl groups, or both acryloyl and methacryloyl groups as (meth)acryloyl groups.

[0062] The polyfunctional macromonomer (a4) may have (meth)acryloyl groups at either the molecular chain ends or side chains, or both, of the (meth)acrylic acid ester polymer backbone. 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 chain.

[0063] 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)acrylate). (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).

[0064] 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.

[0065] 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.

[0066] In the graft copolymer according to this embodiment, 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 graft copolymer can be increased, and the strength of the cured product can be further increased.

[0067] 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.

[0068] Furthermore, from the viewpoint of the effects described above, the content of polymer block (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.

[0069] The average number of polymer blocks (B) per molecule of the graft copolymer according to this embodiment is preferably 0.05 or more and 2.0 or less, from the viewpoint of the strength of the resulting cured product. The lower limit is more preferably 0.07 or more, and even more preferably 0.08 or more. The upper limit is more preferably 1.5 or less, and even more preferably 1.0 or less. The average number can be calculated using the following formula: Formula: Number average molecular weight of the graft copolymer (g / mol) / (Weight of the graft copolymer (g) / (Number of moles of polymer blocks (B)))

[0070] <Block Bonding Configuration> In this embodiment, the graft copolymer has polymer block (A) and polymer block (B) bonded in the order A-B-A. However, the graft copolymer is not limited to A-B-A triblocks, and may further include multiblocks in which block (B) and / or block (A) are further bonded to the triblock, or A-B diblocks, etc.

[0071] The graft copolymer according to this embodiment can be prepared by free radical polymerization. When prepared by free radical polymerization, some molecules in the graft copolymer may include polymer components in which block (A) and block (B) are not bonded to each other. In this application, "graft copolymer" is defined to include 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.

[0072] In the graft copolymer according to this embodiment, polymer block (A) and polymer block (B) are preferably linked via ester bonds (i.e., ester bonds in the general formula (4)) derived from the (meth)acryloyl group in the polyfunctional macromonomer (a4).

[0073] The bonding configuration between polymer block (A) and polymer block (B) is not particularly limited, but can be represented by the following general formula (2): A - C (= O) - O - B (2) In each formula, A represents the (meth)acrylic acid ester polymer skeleton of polymer block (A), and B represents the (meth)acrylic acid ester polymer skeleton of polymer block (B).

[0074] Polymer block (A) and polymer block (B) exhibit different glass transition temperatures, but it is particularly 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 during heating and melting, good initial fixation after heating and melting, and can achieve high strength after curing.

[0075] In this case, the glass transition temperature of polymer block (A) is preferably 45°C or higher, and more preferably 60°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 represents the glass transition temperature (K) of the homopolymer of monomer i.)

[0076] 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.

[0077] When the 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 the polymer block (A) contains an alkyl methacrylate ester with three or fewer C1 atoms in the alkyl group.

[0078] 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.

[0079] The graft copolymer according to this embodiment may have a linear structure in which the ends of polymer block (A) and polymer block (B) are connected, but it is preferable to include an H-type structure. Figure 1 shows a conceptual diagram of the H-type structure. In this structure, the two vertical bars correspond to polymer block (A), and the one horizontal bar corresponds to 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.

[0080] The H-type structure can be formed by randomly polymerizing a polyfunctional macromonomer (a4), which has (meth)acryloyl groups at both ends of the (meth)acrylic acid ester polymer molecular chain, with a (meth)acrylic acid ester (a1) and a chain transfer agent (a2) having a mercapto group.

[0081] <Molecular Weight of Graft Copolymer> The number-average molecular weight of the graft copolymer according to this embodiment is not particularly limited, but is preferably 500 to 50,000 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 is preferably 7,000 or less, more preferably 5,000 or less, and even more preferably 4,000 or less.

[0082] The weight-average molecular weight of the graft copolymer 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 is preferably 40,000 or less, as this yields a cured product with low viscosity and high strength.

[0083] The molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of the graft copolymer is not particularly limited, but from the viewpoint of making the graft copolymer low viscosity, it is preferably 3.0 to 11.0 and more preferably 5.0 to 10.0.

[0084] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the graft copolymer are measured in polystyrene equivalents by gel permeation chromatography (GPC). The detailed measurement method is described in the examples. As mentioned above, the graft copolymer 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 are values ​​measured for the entire graft copolymer, including such polymer components.

[0085] <Method for Producing Graft Copolymers> The graft copolymer according to this embodiment can be produced by polymerizing a (meth)acrylic acid ester (a1), a chain transfer agent having a mercapto group (a2), any other monomer (a3), and a polyfunctional macromonomer (a4). The polymerization method is not particularly limited, but may be a general free radical polymerization. According to this embodiment, despite being free radical polymerization, polymerization can be controlled, a graft copolymer can be produced, and its molecular weight distribution can be made relatively narrow.

[0086] 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.

[0087] 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.

[0088] As described above, the graft copolymer will 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).

[0089] However, the following methods can also be used in combination to further introduce reactive silicon groups into the graft copolymer: (i) A monomer having a reactive functional group (V group) is copolymerized with a (meth)acrylic acid ester (a1), and then the resulting copolymer is reacted 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 have functional groups introduced at the polymer ends, and reactive silicon groups can be introduced at the polymer ends by modifying them.

[0090] 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.

[0091] 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.

[0092] <<Curable Composition>> The graft copolymer according to this embodiment can constitute a curable composition. The curable composition preferably contains a silanol condensation catalyst to promote the condensation reaction of the reactive silicon groups in the graft copolymer.

[0093] <Silanol Condensation Catalysts> Examples of silanol condensation catalysts include organotin compounds, metal carboxylic acid salts, amine compounds, carboxylic acids, and alkoxy metals.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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).

[0099] When using a silanol condensation catalyst, the amount used is preferably 0.001 to 20 parts by weight, more preferably 0.01 to 15 parts by weight, and even more preferably 0.01 to 10 parts by weight, per 100 parts by weight of the graft copolymer according to this embodiment, from the viewpoint of promoting the condensation reaction of reactive silicon groups.

[0100] <<Other Additives>> In addition to the graft copolymer and silanol condensation catalyst according to this embodiment, the curable composition according to this embodiment may also contain plasticizers, fillers, adhesion promoters, dehydrating agents, rheology control agents, antioxidants, light stabilizers, ultraviolet absorbers, and other resins as additives.

[0101] Furthermore, various additives may be added to the curable composition according to this embodiment as needed, for the purpose of adjusting the physical properties of the curable composition or the cured product. Examples of such additives include solvents, diluents, photocurable substances, oxygen-curable substances, surface modifiers, silicates, curability modifiers, radical inhibitors, metal deactivators, ozone degradation inhibitors, phosphorus-based peroxide decomposers, lubricants, pigments, antifungal agents, flame retardants, and foaming agents.

[0102] <Plasticizers> Plasticizers can be added to curable compositions. The addition of plasticizers can reduce the viscosity of the curable composition, making it easier to handle.

[0103] 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.

[0104] 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.

[0105] 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 the graft copolymer.

[0106] <Fillers> Fillers can be added to the curable composition. The strength of the cured product can be improved by adding fillers.

[0107] 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.

[0108] 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.

[0109] <Adhesion-improving agent> An adhesion-improving agent may be added to the curable composition. As the adhesion-improving agent, a silane coupling agent or a reaction product of a silane coupling agent may be added.

[0110] 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.

[0111] The amount of adhesion promoter added is preferably 0.1 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight, per 100 parts by weight of graft copolymer.

[0112] <Dehydrating Agent> A dehydrating agent may be added to the curable composition. Here, the dehydrating agent is preferably a compound that can react with water, more preferably a silicon compound that can react with water (excluding compounds that are adhesive imparters), and particularly preferably a trialkoxysilane compound.

[0113] Specific examples of the dehydrating agent are not limited to vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and other vinyl group-containing silanes. The dehydrating agent may be used alone or in combination of two or more types.

[0114] The amount of dehydrating agent added is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, and even more preferably 1 to 5 parts by weight, per 100 parts by weight of graft copolymer.

[0115] <Rheology Control Agent> Rheology control agents may be added to the curable composition as needed to prevent sagging and improve workability.

[0116] 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.

[0117] The amount of rheology control agent added is preferably 0.1 to 20 parts by weight per 100 parts by weight of graft copolymer.

[0118] <Antioxidants> Antioxidants (anti-aging agents) can be used in the curable composition. Using antioxidants can improve the weather resistance of the cured product. Examples of antioxidants include hindered phenols, monophenols, bisphenols, and polyphenols. Specific examples of antioxidants are also described in Japanese Patent Publication No. 4-283259 and Japanese Patent Publication No. 9-194731. The amount of antioxidant added is preferably 0.1 to 10 parts by weight, and more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the graft copolymer.

[0119] <Light stabilizers> Light stabilizers can be used in the curable composition. Using light stabilizers can prevent photo-oxidative degradation of the cured product. Examples of light stabilizers include benzotriazole-based, hindered amine-based, and benzoate-based compounds, but hindered amine-based compounds are particularly preferred. The amount of light stabilizer added is preferably 0.1 to 10 parts by weight, and more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the graft copolymer.

[0120] <UV Absorbers> UV absorbers can be used in the curable composition. Using UV absorbers can improve the surface weather resistance of the cured product. Examples of UV absorbers include benzophenone-based, benzotriazole-based, salicylate-based, substituted tolyl-based, and metal chelate compounds, but benzotriazole-based compounds are particularly preferred, 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 the graft copolymer.

[0121] A curable composition according to one embodiment of the present invention can be prepared as a one-component type that hardens upon application by moisture in the air after the composition has been pre-mixed and sealed for storage. In this case, it is preferable to dehydrate and dry any components containing moisture before use, or to dehydrate them by reducing pressure during mixing.

[0122] Furthermore, a curable composition according to one embodiment of the present invention can also be prepared as a two-component type, comprising a main component containing a graft copolymer and a curing agent containing components such as a silanol condensation catalyst, filler, plasticizer, and water, and the main component and curing agent are mixed before use.

[0123] There are no particular limitations on the method for preparing the curable composition according to one embodiment of the present invention. For example, conventional methods such as blending the above components and kneading them at room temperature or under heating using a mixer, roll, kneader, etc., or dissolving and mixing the above components using a small amount of a suitable solvent can be employed.

[0124] A curable composition according to one embodiment of the present invention can exhibit good adhesion to various substrates such as plastics, metals, and composite materials. Furthermore, when used as an adhesive for non-polar materials such as polypropylene or engineering plastics having rigid molecular chains such as polyphenylene sulfide, the substrate can be pre-treated by known methods to enhance adhesion to these substrates and obtain stable adhesive strength. For example, surface treatment techniques such as sanding, flame treatment, corona discharge, arc discharge, and plasma treatment can be used. Plasma treatment is preferred because it causes less damage to the substrate and provides stable adhesion. These surface treatments are also effective in removing mold release agents that remain on the substrate surface after molding.

[0125] The cured product obtained by curing the curable composition according to one embodiment of the present invention has good adhesion to various substrates, and therefore the curable composition can be used as an adhesive, sealant, or tack. In particular, the curable composition according to one embodiment of the present invention is solid at room temperature but becomes fluid when heated and melted, allowing it to be applied to a substrate, and therefore can be suitably used as a hot-melt type curable composition, especially a hot-melt type adhesive.

[0126] In order to ensure workability when applying the curable composition according to one embodiment of the present invention to a substrate, it is preferable to heat it to a high temperature to reduce its viscosity, preferably around 70 to 180°C, more preferably 90 to 160°C, and even more preferably 100 to 150°C. The method of heating is not particularly limited, and conventionally known methods can be used.

[0127] A curable composition according to one embodiment of the present invention can exhibit desired physical properties by performing a long curing (curing) process after bonding the adherends. The conditions for the curing (curing) process are not particularly limited, but examples include a temperature of 5 to 90°C and a duration of 24 hours to 1 week.

[0128] When the curable composition according to one embodiment of the present invention is used as a hot-melt curable composition, it can be used as a reactive hot-melt adhesive. This curable composition is suitable as an adhesive for joining panels of buses, trailers, trains, etc., as an adhesive for joining displays and housings in smartphones, tablet devices, and laptop computers, as an adhesive for clothing, and for joining dissimilar materials such as aluminum-steel, steel-composite materials, and aluminum-composite materials. When joining dissimilar materials, it is preferable to cover the joint with a sealer to prevent corrosion. As the sealer, a polymer having reactive silicon groups as shown in this application can be used.

[0129] The curable composition according to one embodiment of the present invention is more preferably used as an adhesive in automotive parts such as vehicle panels, large vehicle parts such as trucks and buses, train car parts, aircraft parts, ship parts, electrical parts, and various mechanical parts.

[0130] 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 graft copolymer comprising a (meth)acrylic acid ester polymer block (A) having a reactive silicon group represented by (A) and a (meth)acrylic acid ester polymer block (B) having a number average molecular weight of 7,000 or more, bonded in the order A-B-A, wherein the polymer block (A) and the polymer block (B) have different glass transition temperatures, the reactive silicon group equivalent of the graft copolymer is 0.15 mmol / g or more, the content of alkyl (meth)acrylic acid esters with 7 or more C 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, and the content of alkyl (meth)acrylic acid esters with 3 or fewer C atoms in the alkyl group contained in the polymer block (A) is 25% by weight or more in the graft copolymer. [Item 2] The graft copolymer according to Item 1, wherein the glass transition temperature of polymer block (A) is higher than the glass transition temperature of polymer block (B). [Item 3] The graft copolymer according to Item 2, wherein the glass transition temperature of polymer block (A) is 45°C or higher, and the glass transition temperature of polymer block (B) is 0°C or lower. [Item 4] The graft copolymer according to any one of Items 1 to 3, wherein the alkyl (meth)acrylate ester containing alkyl with 3 or fewer carbon atoms in the polymer block (A) is an alkyl methacrylate ester containing alkyl with 3 or fewer carbon atoms. [Item 5] The graft copolymer according to any one of Items 1 to 4, wherein the polymer block (B) is an acrylic acid ester polymer block. [Item 6] The graft copolymer according to any one of Items 1 to 5, wherein the polymer block (A) contains 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 4,000 to 10,000 ppm in the graft copolymer. [Item 7] The graft copolymer according to any one of Items 1 to 6, wherein the polymer block (A) includes constituent units derived from a chain transfer agent (a2) having a mercapto group, and the molar ratio of the polymer block (B) to the chain transfer agent (a2) is 0.10 to 0.40.[Item 8] The graft copolymer according to any one of Items 1 to 7, wherein the number average molecular weight of the polymer block (B) is 8,000 to 18,000. [Item 9] The graft copolymer according to any one of Items 1 to 8, 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 10] A hot-melt adhesive comprising the graft copolymer according to any one of Items 1 to 9.

[0131] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the present invention.

[0132] 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

[0133] (Sulfur atom concentration) The sulfur atom concentration is a theoretical value calculated from the total amount of components used in the production of the graft copolymer and the amount of chain transfer agent (a2) having a mercapto group.

[0134] (Synthesis Example 1) 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), and hydrotalcite (Kyoward 500SH: manufactured by Kyowa Chemical) 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. The 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. The mixture was reacted at 70°C for 3 hours, and the solvent was removed by distillation under reduced pressure to obtain a polymer concentrate. The concentrate was diluted with toluene, and the solid components were filtered off. The filtrate was concentrated under reduced pressure to obtain a (meth)acrylic acid ester polymer (b-1) 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.

[0135] (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 1.8 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), and hydrotalcite (Kyoward 500SH: manufactured by Kyowa Chemical) 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. The crude polymer, 1.9 parts by weight of potassium acrylate, 100 ppm of 4-hydroxy-TEMPO, and 100 parts by weight of dimethylacetamide as a solvent were added. The mixture was reacted at 70°C for 3 hours, and the solvent was removed by distillation under reduced pressure to obtain a polymer concentrate. The concentrate was diluted with toluene, and the solid components were filtered off. The filtrate was concentrated under reduced pressure 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 21,210 (GPC molecular weight), and a molecular weight distribution (Mw / Mn) of 1.14.

[0136] (Synthesis Example 3) 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 6.2 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), and hydrotalcite (Kyoward 500SH: manufactured by Kyowa Chemical) 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. The crude polymer, 1.9 parts by weight of potassium acrylate, 100 ppm of 4-hydroxy-TEMPO, and 100 parts by weight of dimethylacetamide as a solvent were added. The mixture was reacted at 70°C for 3 hours, and the solvent was removed by distillation under reduced pressure to obtain a polymer concentrate. The concentrate was diluted with toluene, and the solid components were filtered off. The filtrate was concentrated under reduced pressure to obtain a (meth)acrylic acid ester polymer (b-3) having acryloyl groups at both ends (i.e., two acryloyl groups in one polymer molecule), a number-average molecular weight of 5,600 (GPC molecular weight), and a molecular weight distribution (Mw / Mn) of 1.15.

[0137] (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 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. 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 (meth)acrylic acid ester copolymer (A-1) with a number average molecular weight of 3,860 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.045 mmol / g, the reactive silicon group equivalent was 0.32 mmol / g, and the sulfur atom concentration was 5,217 ppm.

[0138] (Synthesis Example 5) 42.2 parts by weight of butyl acetate was placed in a four-necked flask equipped with a stirrer and heated to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 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-2) prepared in Synthesis Example 2, 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. 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 (meth)acrylic acid ester copolymer (A-2) with a number average molecular weight of 3,730 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.023 mmol / g, the reactive silicon group equivalent was 0.32 mmol / g, and the sulfur atom concentration was 5,217 ppm.

[0139] (Synthesis Example 6) 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, 2.0 parts by weight of butyl acrylate, 48.4 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 2.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2-methylbutyronitrile) in 17.1 parts by weight of butyl acetate was added dropwise over 3 hours. 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 (meth)acrylic acid ester copolymer (A-3) with a number average molecular weight of 3,470 (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 5,217 ppm.

[0140] (Synthesis Example 7) 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-1) prepared in Synthesis Example 1, 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 (meth)acrylic acid ester copolymer (A-4) 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.

[0141] (Synthesis Example 8) 42.2 parts by weight of ethyl acetate was placed in a four-necked flask equipped with a stirrer and heated to 80°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 37.7 parts by weight of methyl methacrylate, 3.2 parts by weight of butyl acrylate, 0.5 parts by weight of 2-ethylhexyl acrylate, 4.5 parts by weight of stearyl methacrylate, 49.4 parts by weight of the polyfunctional macromonomer (b-2) prepared in Synthesis Example 2, 1.5 parts by weight of 3-methacryloxypropyltrimethoxysilane, 3.2 parts by weight of 3-mercaptopropyltrimethoxysilane, and 0.9 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) in 17.1 parts by weight of ethyl acetate was added dropwise over 3 hours. Furthermore, a mixed solution of 0.3 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) dissolved in 5.7 parts by weight of ethyl acetate was added, and polymerization was carried out at 80°C for 2 hours to obtain an ethyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (A-5) with a number average molecular weight of 4,280 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.023 mmol / g, the reactive silicon group equivalent was 0.22 mmol / g, and the sulfur atom concentration was 5,217 ppm.

[0142] (Synthesis Example 9) 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 40.8 parts by weight of methyl methacrylate, 16.6 parts by weight of butyl acrylate, 0.3 parts by weight of 2-ethylhexyl acrylate, 0.3 parts by weight of stearyl methacrylate, 39.6 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 0.3 parts by weight of 3-methacryloxypropyltrimethoxysilane, 2.1 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. 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 (meth)acrylic acid ester copolymer (P-1) with a number average molecular weight of 5,830 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.037 mmol / g, the reactive silicon group equivalent was 0.12 mmol / g, and the sulfur atom concentration was 3,423 ppm.

[0143] (Synthesis Example 10) 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 51.4 parts by weight of methyl methacrylate, 18.8 parts by weight of butyl acrylate, 0.4 parts by weight of 2-ethylhexyl acrylate, 0.4 parts by weight of stearyl methacrylate, 25.0 parts by weight of the polyfunctional macromonomer (b-1) prepared in Synthesis Example 1, 2.6 parts by weight of 3-methacryloxypropyltrimethoxysilane, 1.4 parts by weight of n-dodecyl mercaptan, 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 (meth)acrylic acid ester copolymer (P-2) with a number average molecular weight of 9,320 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.023 mmol / g, the reactive silicon group equivalent was 0.10 mmol / g, and the sulfur atom concentration was 2,213 ppm.

[0144] (Synthesis Example 11) 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 20.0 parts by weight of methyl methacrylate, 24.4 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. 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 (meth)acrylic acid ester copolymer (P-3) with a number average molecular weight of 4,230 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.045 mmol / g, the reactive silicon group equivalent was 0.32 mmol / g, and the sulfur atom concentration was 5,217 ppm.

[0145] (Synthesis Example 12) 42.2 parts by weight of butyl acetate was placed in a four-necked flask equipped with a stirrer and heated to 115°C under a nitrogen atmosphere. A mixed solution prepared by dissolving 30.5 parts by weight of methyl methacrylate, 0.7 parts by weight of butyl acrylate, 13.2 parts by weight of stearyl methacrylate, 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. 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 (meth)acrylic acid ester copolymer (P-4) with a number average molecular weight of 4,220 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.045 mmol / g, the reactive silicon group equivalent was 0.32 mmol / g, and the sulfur atom concentration was 5,217 ppm.

[0146] (Synthesis Example 13) 42.2 parts by weight of ethyl acetate was placed in a four-necked flask equipped with a stirrer and heated to 80°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-3) prepared in Synthesis Example 3, 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(2,4-dimethylvaleronitrile) in 17.1 parts by weight of ethyl acetate was added dropwise over 3 hours. Furthermore, a mixed solution of 0.3 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) dissolved in 5.7 parts by weight of ethyl acetate was added, and polymerization was carried out at 80°C for 2 hours to obtain an ethyl acetate solution (60% solids) of a reactive silicon group-containing (meth)acrylic acid ester copolymer (P-5) with a number average molecular weight of 4,000 (GPC molecular weight). The polyfunctional macromonomer equivalent of the solids in this solution was 0.086 mmol / g, the reactive silicon group equivalent was 0.32 mmol / g, and the sulfur atom concentration was 5,217 ppm.

[0147] (Example 1) The butyl acetate solution of the graft copolymer obtained in Synthesis Example 4 was heated and defoliated to obtain a solid graft polymer (A-1) at room temperature.

[0148] (Complex Viscosity and Complex Modulus) Dynamic viscoelasticity measurements were performed on the obtained graft copolymer (A-1) using a parallel disc plate with a diameter of 20 mm as a jig, with a gap set to 0.5 mm, while cooling from 150°C to 10°C. The complex viscosity was recorded at 120°C, and the complex modulus was recorded at 23°C. The results are shown in Table 1. A rheometer (DHR-2) manufactured by TA Instruments was used.

[0149] (Tensile Properties) 100 parts by weight of graft copolymer (A-1) was heated and melted at 140°C, and 2 parts by weight of KBM-603 (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.2 parts by weight of U-810 (dioctyl tin dilaurate, manufactured by Nitto Chemical Co., Ltd.) were added and mixed to prepare a sheet with a thickness of approximately 2 mm, which was cured for 7 days under 23°C and 50% RH conditions. The obtained sheet was punched out into a No. 3 dumbbell shape (JIS K 6251), and a tensile strength test was performed at an elongation rate of 50 mm / min, and the stress at 50% elongation (M50), strength at fracture (TB), and elongation at fracture (EB) were measured. The apparatus used was an Autograph (AGS-X) manufactured by Shimadzu Corporation. The results are shown in Table 1.

[0150] (Examples 2-3, 5 and Comparative Examples 1-4) The butyl acetate solutions of the graft copolymers obtained in Synthesis Examples 5-6 and 8-13 were heated and defoliated to obtain solid graft polymers (A-2), (A-3), (A-5), (P-1) to (P-5) at room temperature. For each of the obtained graft copolymers, the complex viscosity, complex modulus, and tensile properties were measured in the same manner as in Example 1. The results are shown in Table 1.

[0151]

[0152] Table 1 shows the following: In Examples 1-3 and 5, the complex viscosity measured at 120°C was small, indicating low viscosity during heating and melting. Furthermore, the complex modulus measured at 23°C after cooling from 150°C was relatively large, indicating good initial fixation immediately after heating and melting the graft copolymer and bonding it to the adherend. In addition, the fracture strength measured for the cured product was also good.

[0153] On the other hand, Comparative Examples 1 and 2, which evaluated graft copolymers with a reactive silicon group equivalent of less than 0.15 mmol / g, showed lower tensile strengths compared to Examples 1 to 3. Comparative Examples 1 and 2 evaluated polymers corresponding to B-4 and B-10 described in Patent Document 1, Table 2. Furthermore, Comparative Example 3, which evaluated a graft copolymer with an alkyl (meth)acrylate ester content of less than 25% by weight in the graft copolymer, showed an extremely small complex modulus and insufficient initial fixation. It also showed a low tensile strength.

[0154] Furthermore, in Comparative Example 4, where the content of alkyl (meth)acrylate (SMA) with 7 or more C atoms in the polymer block (A) exceeded 10% by weight in the graft copolymer, the complex modulus was extremely small, indicating insufficient initial fixation. The tensile strength was also low.

[0155] Furthermore, Comparative Example 5, which evaluated a graft copolymer containing a (meth)acrylic acid ester polymer block (B) with a number-average molecular weight of less than 7,000, showed a lower tensile strength compared to Examples 1 to 3.

[0156] (Example 4) The butyl acetate solution of the graft copolymer obtained in Synthesis Example 7 was heated and defoliated to obtain a solid graft polymer (A-4) at room temperature. The complex viscosity, complex modulus, and tensile properties of the obtained graft copolymer were measured in the same manner as in Example 1. The results are shown in Table 2.

[0157]

[0158] Table 2 shows that, similar to Examples 1-3, Example 4 also exhibited good initial fixation, with a low complex viscosity measured at 120°C, a relatively high complex modulus measured at 23°C, and good fracture strength measured on the cured product.

Claims

1. General formula (1): -SiR １ ３－ａ X ａ (1) (wherein, R １ A graft copolymer comprising a (meth)acrylic acid ester polymer block (A) having a reactive silicon group represented by (A) and a (meth)acrylic acid ester polymer block (B) having a number average molecular weight of 7,000 or more, bonded in the order A-B-A, wherein the polymer block (A) and the polymer block (B) have different glass transition temperatures, the reactive silicon group equivalent of the graft copolymer is 0.15 mmol / g or more, the content of alkyl (meth)acrylic acid esters with 7 or more C 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, and the content of alkyl (meth)acrylic acid esters with 3 or fewer C atoms in the alkyl group contained in the polymer block (A) is 25% by weight or more in the graft copolymer.

2. The graft copolymer according to claim 1, wherein the glass transition temperature of polymer block (A) is higher than the glass transition temperature of polymer block (B).

3. The graft copolymer according to claim 2, wherein the glass transition temperature of polymer block (A) is 45°C or higher, and the glass transition temperature of polymer block (B) is 0°C or lower.

4. The graft copolymer according to any one of claims 1 to 3, wherein the alkyl (meth)acrylate ester containing alkyl with 3 or fewer carbon atoms in the polymer block (A) is an alkyl methacrylate ester with 3 or fewer carbon atoms in the alkyl group.

5. The graft copolymer according to any one of claims 1 to 3, wherein the polymer block (B) is an acrylic acid ester polymer block.

6. The graft copolymer according to any one of claims 1 to 3, wherein the polymer block (A) includes 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 4,000 to 10,000 ppm in the graft copolymer.

7. The graft copolymer according to any one of claims 1 to 3, wherein the polymer block (A) comprises a structural unit derived from a chain transfer agent (a2) having a mercapto group, and the molar ratio of the polymer block (B) to the chain transfer agent (a2) is 0.10 to 0.

40.

8. The graft copolymer according to any one of claims 1 to 3, wherein the number average molecular weight of the polymer block (B) is 8,000 to 18,000.

9. The graft copolymer according to any one of claims 1 to 3, 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).

10. A hot-melt adhesive comprising the graft copolymer described in any one of claims 1 to 3.

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