Curable resin composition and sealant composition

Abstract

To provide a curable resin composition which enables production of a cured product that is excellent in coating property and is also excellent in tensile characteristics and weather resistance, and a sealing material composition containing the curable resin composition.SOLUTION: A curable resin composition contains: a (meth)acrylic polymer (I) which has a number average molecular weight of 30,000 or more and 80,000 or less and molecular weight distribution (Mw / Mn) of 2.2 or less, and has an average number of crosslinkable silyl groups in one molecule of 1.8 pieces or more; and a (meth)acrylic polymer (II) which has a weight average molecular weight of 10,000 or more and 50,000 or less, and has an average number of crosslinkable silyl groups in one molecule of 0.50 pieces or more and less than 1.8 pieces.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present specification relates to a curable resin composition and a sealant composition. [Background technology]

[0002] Vinyl copolymers having crosslinkable functional groups obtained by radical polymerization are well known as curable resins used in industrial applications. These vinyl copolymers are used as curable resin compositions and are widely used in the fields of cured products such as adhesives, sealants, paints, coatings, molding materials, and rubber sheets.

[0003] As such a curable resin composition, Patent Document 1 discloses a composition containing a vinyl polymer (I) having at least one crosslinkable silyl group, the main chain of which is produced by living radical polymerization, and the molecular weight distribution of which is less than 1.8, and a vinyl polymer (II) having a crosslinkable silyl group and the main chain of which is produced by free radical polymerization, wherein the weight ratio of the vinyl polymer (I) to the vinyl polymer (II) is 10:90 to 90:10. Furthermore, in the examples of the same document, it is specifically described that the number average molecular weight of the vinyl polymer (I) is in the range of 18,000 to about 20,000, the molecular weight distribution is in the range of 1.2 to 1.3, and the number of crosslinkable silyl groups introduced per polymer molecule is in the range of 1.8 to 2.0 (Production Examples 1 and 3), and that the number average molecular weight of the vinyl polymer (II) is about 2,100, and the number of crosslinkable silyl groups introduced per polymer molecule is 1.27 (calculated values ​​based on Production Example 2), and that the cured product of the curable resin composition containing the vinyl polymer (I) and the vinyl polymer (II) has excellent tensile properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2004 / 074381 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, particularly in sealing material applications, high levels of tensile properties and weather resistance have been required. However, the examples in Patent Document 1 do not include any specific description of experimental results on the weather resistance of the cured product, and insufficient weather resistance can be problematic, so there is a need for a combination of weather resistance and coatability.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a curable resin composition that is excellent in coatability and that can give a cured product that is excellent in tensile properties and weather resistance, and further to provide a sealant composition containing the curable resin composition. [Means for solving the problem]

[0007] As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a curable resin composition containing two types of (meth)acrylic polymers, in which the number average molecular weight, molecular weight distribution, and average number of crosslinkable silyl groups per molecule of one polymer are within specific ranges, and the weight average molecular weight and average number of crosslinkable silyl groups per molecule of the other polymer are within specific ranges, provides a cured product with excellent tensile properties and weather resistance.

[0008] The present invention is as follows. [1] A curable resin composition comprising: a (meth)acrylic polymer (I) having a number-average molecular weight of 30,000 or more and 80,000 or less, a molecular weight distribution (Mw / Mn) of 2.2 or less, and an average number of crosslinkable silyl groups per molecule of 1.8 or more; and a (meth)acrylic polymer (II) having a weight-average molecular weight of 10,000 or more and 50,000 or less, and an average number of crosslinkable silyl groups per molecule of 0.50 or more and less than 1.8. [2] The curable resin composition according to [1], wherein the (meth)acrylic polymer (I) is a block copolymer. [3] The block copolymer according to [2], wherein the block copolymer has a structural unit consisting of polymer block (A) / polymer block (B) / polymer block (A). [4] The curable resin composition according to any one of [1] to [3], wherein the (meth)acrylic polymer (I) contains a structural unit derived from a (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms. [5] The curable resin composition according to any one of [1] to [4], wherein the (meth)acrylic polymer (II) contains a structural unit derived from a (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms. [6] The curable resin composition according to any one of [1] to [5], wherein the content of the (meth)acrylic polymer (I) is 25 to 80 mass% and the content of the (meth)acrylic polymer (II) is 20 to 75 mass%, when the total of the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II) is 100 mass%. [7] The curable resin composition according to any one of [1] to [6], further comprising an oxyalkylene polymer (III) having a crosslinkable silyl group. [8] The curable resin composition according to any one of [1] to [7], which has a viscosity at 25°C of 100 to 400 Pa·s. [9] A sealant composition containing the curable resin composition according to any one of [1] to [8]. [Effects of the Invention]

[0009] The curable resin composition of the present invention can provide a cured product that has excellent coatability, tensile properties (especially elongation at break), and weather resistance. DETAILED DESCRIPTION OF THE INVENTION

[0010] Various embodiments of the technology disclosed in this specification are described in detail below. In this specification, "(meth)acrylic" means acrylic and methacrylic, "(meth)acrylate" means acrylate and methacrylate, and "(meth)acryloyl group" means acryloyl group and methacryloyl group. Hereinafter, the methods for producing the (meth)acrylic polymer (I), the (meth)acrylic polymer (II), the curable resin composition, and the block copolymer will be described.

[0011] 1. (Meth)acrylic polymer (I) The (meth)acrylic polymer (I) of the present invention has a number average molecular weight of 30,000 or more and 80,000 or less, a molecular weight distribution (Mw / Mn) of 2.2 or less, and an average number of crosslinkable silyl groups per molecule of 1.8 or more. The term "crosslinkable silyl group" refers to a group that can form a crosslinked structure based on, for example, a siloxane bond through hydrolysis and condensation. Specifically, it is a group in which a hydroxy group or a hydrolyzable group (such as an alkoxy group) is bonded to a silicon atom. By having 1.8 or more crosslinkable silyl groups in one molecule of the (meth)acrylic polymer (I), a crosslinked structure between the (meth)acrylic polymers (I) or a crosslinked structure between the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II) can be formed, and the weather resistance of the cured product of the curable resin composition can be improved.

[0012] As described above, the number-average molecular weight (Mn) of the (meth)acrylic polymer (I) is 30,000 or more and 80,000 or less from the viewpoint of tensile properties (elongation at break, strength at break, etc.). If Mn is 30,000 or more, the cured product can have excellent weather resistance. If Mn is 80,000 or less, good fluidity and coatability can be ensured. From the viewpoint of the strength at break and fluidity of the cured product, Mn of the (meth)acrylic polymer (I) is more preferably in the range of 33,000 or more and 70,000 or less, even more preferably in the range of 35,000 or more and 60,000 or less, even more preferably in the range of 38,0000 or more and 50,000 or less, and even more preferably in the range of 40,000 or more and 47,000 or less.

[0013] The molecular weight distribution (Mw / Mn) obtained by dividing the weight-average molecular weight (Mw) of the (meth)acrylic polymer (I) by the number-average molecular weight (Mn) is 2.2 or less, as described above, from the viewpoint of tensile properties (elongation at break, strength at break, etc.). From the viewpoint of ensuring that the (meth)acrylic polymer (I) containing a crosslinkable silyl group forms a uniform crosslinked structure and ensures the tensile properties (elongation at break, strength at break, etc.), it is more preferably 2.0 or less, even more preferably 1.85 or less, still more preferably 1.5 or less, even more preferably 1.35 or less, and even more preferably 1.25 or less. The molecular weight distribution (Mw / Mn) is preferably 1.05 or more, and may be 1.10 or more, or may be 1.20 or more. The above Mn and Mw / Mn can be measured by the method described in the Examples.

[0014] The average number of crosslinkable silyl groups in one molecule of the (meth)acrylic polymer (I) is 1.8 or more, from the viewpoint of improving the weather resistance of the cured product. It is preferably 2.5 or more, more preferably 3.8 or more, even more preferably 4.0 or more, and even more preferably 5.0 or more. Furthermore, from the viewpoint of excellent elongation at break, it is preferably 8.0 or less, more preferably 5.5 or less, and even more preferably 5.2 or less. The average number of crosslinkable silyl groups contained in the (meth)acrylic polymer (I) having a crosslinkable silyl group is 1 It can be calculated by H-NMR measurement and GPC measurement. That is, after identifying the structural units constituting the polymer and determining the monomers used, 1 The polymer composition and the molar fraction of the crosslinkable silyl group-containing monomer are calculated from the integral of the signal at around 3.5 ppm in the H-NMR spectrum, which is derived from the hydrogen atoms bonded to the carbon atoms of the alkoxysilane. The average number of crosslinkable silyl groups per molecule can then be calculated by multiplying this molar fraction by the number-average molecular weight (Mn) obtained by GPC measurement.

[0015] The viscosity of the (meth)acrylic polymer (I) at 25° C. is preferably 150 Pa·s or more and 650 Pa·s or less, and more preferably 250 Pa·s or more and 400 Pa·s or less. When the viscosity is 150 Pa·s or more, sagging of the curable resin composition can be prevented, and when the viscosity is 650 Pa·s or less, good fluidity and coatability of the curable resin composition can be ensured. The viscosity can be measured by the method described in the examples.

[0016] The (meth)acrylic polymer (I) can be obtained, for example, by polymerizing a monomer mixture containing a (meth)acrylic monomer. The (meth)acrylic monomer is a monomer having a (meth)acryloyl group in the molecule, and examples thereof include (meth)acrylic acid alkyl ester compounds described below, compounds represented by general formula (1) described below, and other monomers described below. The amount of the (meth)acrylic monomer used is preferably in the range of 10 to 100% by mass, more preferably 30 to 100% by mass, and even more preferably 50 to 100% by mass, based on the total constituent monomers of the (meth)acrylic polymer (I). Here, the (meth)acrylic polymer (I) may be either a random copolymer or a block copolymer, and is preferably a polymer having a structural unit derived from a hydrolyzable silyl group-containing vinyl compound described below. In view of the excellent weather resistance of the cured product obtained from the curable resin composition, it is preferably a block copolymer (hereinafter also referred to as "the present block copolymer"), and more preferably a block copolymer consisting of at least two polymer blocks. Examples of the polymer block include the polymer block (A) and polymer block (B) shown below.

[0017] 1-1. Polymer block (A) Examples of the monomer constituting the polymer block (A) include (meth)acrylic acid alkyl ester compounds, compounds represented by the following general formula (1), and other monomers described below, and one or more of these can be used. CH2=CR 1 -C(=O)O(R 2 O) n -R 3 (1) (In the formula, R 1 represents hydrogen or a methyl group, and R 2 represents a linear or branched alkylene group having 2 to 6 carbon atoms, and R 3 represents hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. n represents an integer of 1 to 100. Among the above-mentioned monomers, (meth)acrylic acid alkyl ester compounds and compounds represented by the above general formula (1) are preferred in that they are likely to give block copolymers with low Tg and excellent fluidity.

[0018] <(Meth)acrylic acid alkyl ester compound> Specific examples of the (meth)acrylic acid alkyl ester compound include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, and tert-butyl (meth)acrylate. linear or branched (meth)acrylic acid alkyl ester compounds such as (meth)acrylic acid, for example, decyl (meth)acrylate and dodecyl (meth)acrylate; and aliphatic cyclic acrylic acid ester compounds such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.

[0019] Among these, (meth)acrylic acid alkyl ester compounds having an alkyl group of 1 to 8 carbon atoms are preferred because they are particularly likely to produce block copolymers having a low Tg and excellent fluidity. The amount of (meth)acrylic acid alkyl ester having an alkyl group of 1 to 8 carbon atoms used is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more, based on the total constituent monomers of the (meth)acrylic polymer (I). The upper limit is 100% by mass, and may be 90% by mass or less, 80% by mass or less, or 50% by mass or less.

[0020] Among the above, the use of a (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms is preferred because it ensures good compatibility with the oxyalkylene polymer and improves tensile properties and weather resistance. The number of carbon atoms in the alkyl group is preferably 10 to 20, more preferably 12 to 20. The amount of the (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms used is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, based on the total constituent monomers of the (meth)acrylic polymer (I). The upper limit is 100% by mass or less, and may be 90% by mass or less, 80% by mass or less, or 50% by mass or less.

[0021] The proportion of structural units derived from (meth)acrylic acid alkyl ester compounds relative to all structural units of the polymer block (A) can be 50% by mass or more and 100% by mass or less. This is because a proportion of 50% by mass or more is advantageous in terms of weather resistance. The proportion of such structural units is, for example, 60% by mass or more, or, for example, 70% by mass or more, or, for example, 80% by mass or more. It is also, for example, 98% by mass or less, or, for example, 95% by mass or less, or, for example, 90% by mass or less, or, for example, 85% by mass or less.

[0022] <Compound represented by general formula (1)> The compound represented by the above general formula (1) has an oxyalkylene structure such as an oxyethylene chain, an oxypropylene chain, or an oxybutylene chain when n is 1. Specific examples include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, n-propoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, n-propoxypropyl (meth)acrylate, n-butoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxybutyl (meth)acrylate, n-propoxybutyl (meth)acrylate, and n-butoxybutyl (meth)acrylate. As the (meth)acrylic acid alkoxyalkyl ester compound, an alkoxyalkyl (meth)acrylic acid ester having an alkoxyalkyl group having 2 to 8 carbon atoms is preferred, and an alkoxyalkyl (meth)acrylic acid ester having an alkoxyalkyl group having 2 to 6 carbon atoms is more preferred, because it is easy to obtain a block copolymer having a low Tg and excellent fluidity.

[0023] When n in the formula is 2 or more, the compound has a polyoxyalkylene structure such as a polyoxyethylene chain, a polyoxypropylene chain, or a polyoxybutylene chain. 2 may be the same or different. Therefore, different types of polyoxyalkylene structures may be present in one molecule, such as a polyoxyethylene / polyoxypropylene block structure. Specific compounds include polyoxyethylene (meth)acrylate, polyoxypropylene (meth)acrylate, polyoxybutylene (meth)acrylate, and polyoxyethylene-polyoxypropylene (meth)acrylate. Examples of compounds having an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms at the terminal include methoxypolyethylene glycol (meth)acrylate, lauroxypolyethylene glycol (meth)acrylate, stearoxypolyethylene glycol (meth)acrylate, octoxypolyethylene glycol polypropylene glycol (meth)acrylate, nonylphenoxypolypropylene glycol (meth)acrylate, and phenoxypolyethylene glycol polypropylene glycol (meth)acrylate.

[0024] <Other monomers> The (meth)acrylic polymer (I) may be copolymerized with other monomers copolymerizable with the above-mentioned monomers. Examples of the other monomers include functional group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate, and ethylene oxide adducts of (meth)acrylic acid; (meth)acrylic acid aromatic esters such as phenyl (meth)acrylate, toluyl (meth)acrylate, and benzyl (meth)acrylate; fluorine-containing (meth)acrylic acid esters such as trifluoromethylmethyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethylmethyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate, perfluoroethylene, perfluoropropylene, and vinylidene fluoride; Aromatic monomers such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, styrenesulfonic acid and its salts; Maleic anhydride; unsaturated dicarboxylic acids such as maleic acid and fumaric acid, and their mono- and di-alkyl esters; maleimide compounds such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, phenylmaleimide, and cyclohexylmaleimide; nitrile group-containing vinyl monomers such as acrylonitrile and methacrylonitrile; Amide group-containing vinyl monomers such as acrylamide and methacrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate; Alkenes such as ethylene and propylene; conjugated dienes such as butadiene and isoprene; Examples of the other monomer include, but are not limited to, vinyl chloride, vinylidene chloride, allyl chloride, allyl alcohol, etc. One or more of these may be used as the other monomer.

[0025] <Crosslinkable silyl group> The average number of crosslinkable silyl groups in each polymer block (A) is preferably 1.8 or more, more preferably 2.5 or more, and even more preferably 3.8 or more, in order to improve the breaking strength of the cured product, and is preferably 8.0 or less, more preferably 6.5 or less, and even more preferably 5.2 or less, in order to achieve excellent breaking elongation.

[0026] The method for introducing the crosslinkable silyl group is not particularly limited, but for example, the crosslinkable silyl group can be introduced by copolymerizing a hydrolyzable silyl group-containing vinyl compound. In this case, the polymer block (A) has a structural unit derived from the hydrolyzable silyl group-containing vinyl compound (hereinafter simply referred to as a "crosslinkable structural unit").

[0027] Examples of hydrolyzable silyl group-containing vinyl compounds include vinyl silanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinyldimethylmethoxysilane; alkoxysilyl group-containing (meth)acrylic acid esters such as trimethoxysilylpropyl (meth)acrylate, triethoxysilylpropyl (meth)acrylate, methyldimethoxysilylpropyl (meth)acrylate, and dimethylmethoxysilylpropyl (meth)acrylate; alkoxysilyl group-containing vinyl ethers such as trimethoxysilylpropyl vinyl ether; and alkoxysilyl group-containing vinyl esters such as vinyl trimethoxysilylundecanoate. These compounds may be used alone or in combination of two or more. The hydrolyzable silyl groups in such vinyl compounds can undergo dehydration condensation. This makes them suitable for efficiently carrying out the polymerization reaction to produce a block copolymer and the subsequent crosslinking reaction. Since the hydrolyzable silyl group as a whole is regarded as one reaction site, in the present invention, the entire hydrolyzable silyl group is regarded as one crosslinkable silyl group. That is, one crosslinkable silyl group is introduced by copolymerizing both vinyltrimethoxysilane, which has three methoxysilyl groups in the molecule, and vinylmethyldimethoxysilane, which has two methoxysilyl groups.

[0028] Another method for introducing bridging silyl functionality is to 1) An addition reaction between a carboxyl group of an unsaturated carboxylic acid, which is a constituent monomer of the polymer block (A), and a hydrolyzable silyl group-containing epoxy compound. The unsaturated carboxylic acid is preferably at least one selected from the group consisting of (meth)acrylic acid, maleic anhydride, and itaconic acid. Another example is 2) an addition reaction between an epoxy group of an epoxy group-containing vinyl compound, which is a constituent monomer of polymer block (A), and a hydrolyzable silyl group-containing amine compound. The epoxy group-containing monomer preferably includes a glycidyl group-containing (meth)acrylic acid ester.

[0029] Furthermore, a polymerizable unsaturated group may be introduced as a crosslinkable functional group into the polymer block (A) by copolymerizing a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups in the molecule. Examples of the polyfunctional polymerizable monomer include compounds having two or more polymerizable functional groups, such as (meth)acryloyl groups and alkenyl groups, in the molecule. Examples include polyfunctional (meth)acrylate compounds, polyfunctional alkenyl compounds, and compounds having both (meth)acryloyl groups and alkenyl groups. Examples include alkylene diol diacrylates such as hexanediol diacrylate, as well as compounds having both (meth)acryloyl groups and alkenyl groups in the molecule, such as allyl (meth)acrylate, isopropenyl (meth)acrylate, butenyl (meth)acrylate, pentenyl (meth)acrylate, and 2-(2-vinyloxyethoxy)ethyl (meth)acrylate. These compounds may be used alone or in combination.

[0030] The polymerizable unsaturated group can also be introduced by producing a polymer having a functional group in the molecule and then reacting it with a compound having a functional group reactive with the functional group and a polymerizable unsaturated group. For example, a polymer having a hydroxy group can be produced and then reacted with a compound having both an isocyanate group and a polymerizable unsaturated group to introduce the polymer into the polymer. Alternatively, for example, a polymer having a carboxy group can be reacted with a compound having both an epoxy group and a polymerizable unsaturated group.

[0031] (number average molecular weight) The number average molecular weight of the polymer block (A) is not particularly limited, but is preferably 2,500 or more and 7,500 or less. When the block copolymer has a plurality of polymer blocks (A), the number average molecular weight of the polymer block (A) refers to the sum of the number average molecular weights of all the polymer blocks (A). In the block copolymer, if the number average molecular weight of the polymer block (A) is 2,500 or more, the cured product can exhibit sufficient breaking strength and weather resistance. Furthermore, if the number average molecular weight is 7,500 or less, good fluidity and coatability can be ensured. From the viewpoint of the strength and fluidity of the cured product, the number average molecular weight of the polymer block (A) is more preferably in the range of 3,000 to 6,500, even more preferably in the range of 3,500 to 6,000, even more preferably in the range of 4,000 to 5,800, and even more preferably in the range of 4,500 to 5,500.

[0032] 1-2. Polymer block (B) Examples of the monomer constituting the polymer block (B) include the above-mentioned (meth)acrylic acid alkyl ester compound and the compound represented by the above-mentioned general formula (1), in the same manner as the polymer block (A) (but different from the polymer block (A)), and one or more of these can be used.

[0033] Among the above monomers, it is preferable that the polymer block (B) has an alkyl acrylate ester as the main structural unit, since this allows for the production of a block copolymer with excellent flexibility. Among these, an alkyl acrylate ester compound having an alkyl group with 4 to 12 carbon atoms is preferred. Furthermore, in consideration of the fluidity of the block copolymer, it is more preferable that the acrylic compound contains an alkyl acrylate ester compound having an alkyl group with 4 to 8 carbon atoms.

[0034] In the polymer block (B), the structural units derived from a (meth)acrylic acid alkyl ester compound can account for 50% by mass or more and 100% by mass or less. More preferably, it is 60% by mass or more and 100% by mass or less, even more preferably, it is 70% by mass or more and 100% by mass or less, and even more preferably, it is 80% by mass or more and 100% by mass or less. When the structural units are within the above range, a block copolymer with good tensile properties tends to be obtained.

[0035] The polymer block (B) may further contain a crosslinkable constituent unit derived from the above-mentioned vinyl monomer having a crosslinkable silyl group.

[0036] The crosslinkable constituent units in the polymer block (B) are preferably present as needed in addition to the crosslinkable constituent units in the polymer block (A). While not particularly limited, the crosslinkable constituent units may be present in an amount of, for example, 0.01 mol % or more, for example, 0.1 mol % or more, or for example, 0.5 mol % or more, relative to the total constituent units of the polymer block (B). If the amount of the crosslinkable constituent units introduced is 0.01 mol % or more, a block copolymer with high breaking strength is easily obtained. From the viewpoint of flexibility, the upper limit of the crosslinkable constituent units is, for example, 20 mol % or less, for example, 10 mol % or less, or for example, 5 mol % or less. From the viewpoint of forming a uniform crosslinked structure, it is preferable to concentrate crosslinking points in the polymer block (A), and it is preferable that the ratio of the crosslinkable constituent units to the total constituent units of the polymer block (B) does not exceed the ratio of the crosslinkable constituent units to the total constituent units of the polymer block (A).

[0037] (number average molecular weight) The number average molecular weight (Mn) of the polymer block (B) is not particularly limited, but is preferably 22,500 or more and 77,500 or less. When the block copolymer has multiple polymer blocks (B), the number-average molecular weight of the polymer block (B) refers to the sum of the number-average molecular weights of all the polymer blocks (B). When the number-average molecular weight of the polymer block (B) is 22,500 or more, the cured product can exhibit sufficient breaking strength and weather resistance. When the number-average molecular weight is 77,500 or less, good fluidity and coatability can be ensured. Since the block copolymer can form a uniform crosslinked structure, the molecular weight of the block copolymer corresponding to the distance between crosslinking points can be ensured. From the viewpoint of the breaking strength and fluidity of the cured product, the polymer block (B) preferably has a molecular weight in the range of 23,500 to 77,000, even more preferably 24,000 to 76,500, even more preferably 24,200 to 76,000, and even more preferably 24,500 to 75,500.

[0038] 1-3. This block copolymer The present block copolymer is a block copolymer consisting of at least two polymer blocks, and preferably has one or more polymer blocks (A) and one or more polymer blocks (B). The present block copolymer may have a structural unit (ABA) consisting of polymer block (A) / polymer block (B) / polymer block (A), or a structural unit (ABC) consisting of polymer block (A) / polymer block (B) / polymer block (C). However, the present block copolymer preferably has the structural unit (ABA) in view of excellent weather resistance of the cured product obtained from the curable resin composition. Examples of the monomer constituting the polymer block (C) include the above-mentioned (meth)acrylic acid alkyl ester compounds, compounds represented by the above-mentioned general formula (1), styrenes, maleimide compounds, and amide group-containing vinyl compounds in the same manner as the polymer blocks (A) and (B) (however, different from the polymer blocks (A) and (B)). One or more of these can be used.

[0039] Here, the block copolymer is A-(BA) n(where n is an integer of 1 or greater) structure, from the viewpoint of the breaking strength of the cured product, it is preferable that the polymer block (A) contains a crosslinkable structural unit. With such a structure, the polymer block (A) containing the crosslinkable structural unit acts as a crosslinked segment, and therefore a uniform crosslinked structure can be obtained while ensuring the molecular weight between crosslinking points, and the cured product can exhibit excellent performance in tensile properties such as breaking elongation and breaking strength.

[0040] The content of polymer block (A) in the block copolymer relative to 100 parts by mass of the total of polymer blocks (A) and (B) is not particularly limited, but is preferably 60 parts by mass or less, more preferably 2 to 60 parts by mass, even more preferably 4 to 50 parts by mass, still more preferably 6 to 40 parts by mass, even more preferably 8 to 30 parts by mass, and still more preferably 10 to 20 parts by mass. When the block copolymer contains crosslinkable structural units, such a range makes it easier to obtain a cured product with good tensile properties from polymer block (A) that serves as a crosslinking point and constitutes a crosslinked segment and polymer block (B) that can become a non-crosslinked segment.

[0041] The preferred ranges of Mn and Mw / Mn of the present block copolymer are the same as the preferred ranges of Mn and Mw / Mn of the (meth)acrylic polymer (I).

[0042] 1-4. Method for producing the block copolymer The present block copolymer is not subject to any particular limitation as long as it is a block copolymer having polymer block (A) and polymer block (B), and known production methods can be used. Examples include methods utilizing various controlled polymerization methods such as living radical polymerization and living anionic polymerization, and methods involving coupling of polymers having functional groups. Among these, living radical polymerization is preferred from the viewpoints of simple operation, applicability to a wide range of monomers, and ability to reduce the content of metal components that may affect durability at high temperatures and obtain a cured product with excellent heat resistance.

[0043] The living radical polymerization may be any of a batch process, a semi-batch process, a tubular continuous polymerization process, a continuous stirred tank process (CSTR), etc. The polymerization method may be applied to various modes such as bulk polymerization without using a solvent, solvent-based solution polymerization, aqueous emulsion polymerization, mini-emulsion polymerization, or suspension polymerization.

[0044] There are no particular limitations on the type of living radical polymerization method, and various polymerization methods can be used, such as reversible addition-fragmentation chain transfer polymerization (RAFT), nitroxy radical polymerization (NMP), atom transfer radical polymerization (ATRP), polymerization using an organotellurium compound (TERP), polymerization using an organoantimony compound (SBRP), polymerization using an organobismuth compound (BIRP), and iodine transfer polymerization. Among these, the RAFT method is preferred from the viewpoints of controllability of polymerization and ease of implementation.

[0045] From the viewpoint of productivity, a method for producing a block copolymer comprising at least two or more polymer blocks preferably includes the steps of: producing, by a RAFT method, a block copolymer (P1) comprising at least three or more polymer blocks and having a trithiocarbonate group represented by general formula (2) in a central polymer block of the block copolymer; and reacting a nucleophile with the trithiocarbonate group of the block copolymer (P1) to produce a block copolymer (P2) comprising at least two or more polymer blocks. [ka]

[0046] 1-4-1. Manufacturing process of block copolymer (P1)

[0047] In the RAFT method, controlled polymerization proceeds via a reversible chain transfer reaction in the presence of a specific polymerization control agent (RAFT agent) and a general free radical polymerization initiator. The RAFT agent can be a compound having a trithiocarbonate group represented by the general formula (2) above. The amount of RAFT agent used is adjusted appropriately depending on the target Mn, the type of monomer and RAFT agent used, etc.

[0048] Examples of compounds having a trithiocarbonate group represented by the above general formula (2) include S,S-dibenzyl trithiocarbonate, bis[4-(2,3-dihydroxypropoxycarbonyl)benzyl]trithiocarbonate, and bis[4-(2-hydroxyethoxycarbonyl)benzyl]trithiocarbonate.

[0049] As the polymerization initiator used in the RAFT polymerization, known radical polymerization initiators such as azo compounds, organic peroxides, and persulfates can be used, but azo compounds are preferred because they are safe and easy to handle and are less likely to cause side reactions during radical polymerization. Specific examples of the azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], and 2,2'-azobis(N-butyl-2-methylpropionamide). The radical polymerization initiators may be used alone or in combination of two or more.

[0050] The proportion of the radical polymerization initiator used is not particularly limited, but from the viewpoint of obtaining a polymer with a narrower molecular weight distribution, the amount of the radical polymerization initiator used per 1 mol of the RAFT agent is preferably 0.5 mol or less, more preferably 0.3 mol or less. Furthermore, from the viewpoint of stably carrying out the polymerization reaction, the lower limit of the amount of the radical polymerization initiator used per 1 mol of the RAFT agent is 0.001 mol. Therefore, the amount of the radical polymerization initiator used per 1 mol of the RAFT agent is preferably in the range of 0.001 mol to 0.5 mol, more preferably 0.005 mol to 0.3 mol.

[0051] The reaction temperature during the polymerization reaction by the RAFT method is preferably 30°C or higher and 120°C or lower, more preferably 40°C or higher and 110°C or lower, and even more preferably 50°C or higher and 100°C or lower. If the reaction temperature is 30°C or higher, the polymerization reaction can proceed smoothly. On the other hand, if the reaction temperature is 120°C or lower, side reactions can be suppressed and restrictions on usable initiators and solvents can be alleviated.

[0052] By using a compound having a trithiocarbonate group represented by the above general formula (2) as a RAFT agent, an A-(BA)n structure consisting of polymer block (A)-polymer block (B)-polymer block (A) can be obtained by living radical polymerization. In this case, first, in the first polymerization step, polymer block (A) is obtained using the constituent monomers of polymer block (A). Then, in the second polymerization step, polymer block (B) is obtained using the constituent monomers of polymer block (B), thereby obtaining an ABA triblock copolymer. Furthermore, in the third polymerization step, polymer block (A) is obtained using the constituent monomers of polymer block (A), thereby obtaining a higher-order block copolymer such as an ABABA pentablock copolymer.

[0053] In the present disclosure, regardless of the polymerization method, polymerization of block copolymer may be carried out in the presence of a chain transfer agent as needed.The chain transfer agent can be a known one, and specifically, ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol, 2-butanethiol, 1-hexanethiol, 2-hexanethiol, 2-methylheptane-2-thiol, 2-butylbutane-1-thiol, 1,1-dimethyl-1-pentanethiol, 1-octanethiol, 2-octanethiol, 1-decanethiol, 3-decanethiol, 1-undecanethiol, 1-dodecanethiol, 2- Examples include alkylthiol compounds having an alkyl group having 2 to 20 carbon atoms, such as dodecanethiol, 1-tridecanethiol, 1-tetradecanethiol, 3-methyl-3-undecanethiol, 5-ethyl-5-decanethiol, tert-tetradecanethiol, 1-hexadecanethiol, 1-heptadecanethiol, and 1-octadecanethiol, as well as mercaptoacetic acid, mercaptopropionic acid, and 2-mercaptoethanol, and one or more of these can be used.

[0054] In the present disclosure, known polymerization solvents can be used in living radical polymerization. Specific examples include orthoester compounds such as trimethyl orthoacetate and triethyl orthoacetate; aromatic compounds such as benzene, toluene, xylene, and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone compounds such as acetone and methyl ethyl ketone; dimethylformamide, acetonitrile, dimethyl sulfoxide, alcohol, and water. Alternatively, bulk polymerization or other methods may be used without using a polymerization solvent.

[0055] 1-4-2. Manufacturing process of block copolymer (P2) The method for producing a polymer of the present invention includes a step of reacting a nucleophilic agent with the trithiocarbonate group in the block copolymer (P1) to obtain a block copolymer (P2). For example, when the block polymer (P1) is a triblock copolymer, the block polymer (P2) can be obtained as a diblock copolymer, and when the block polymer (P1) is a pentablock copolymer, the block polymer (P2) can be obtained as a triblock copolymer.

[0056] Examples of the nucleophilic agent include ammonia, primary and / or secondary amine compounds, alkali metal alkoxides, hydroxides, and thiols, and known compounds can be used. By reacting a nucleophilic agent with a thiocarbonylthio group, the thiocarbonylthio group is converted to a thiol group, and the thiol group undergoes a Michael addition reaction with the remaining acrylate compound, resulting in a reduced odor of the resulting block copolymer. Among these, primary and / or secondary amine compounds are preferred in terms of reactivity.

[0057] The molar equivalent of the nucleophilic agent relative to the thiocarbonylthio group is 2 to 90 molar equivalents. From the viewpoint of reaction efficiency, 3 molar equivalents or more is preferable, and the lower limit may be 4 molar equivalents or more, 5 molar equivalents or more, 10 molar equivalents or more, or 15 molar equivalents or more. Furthermore, from the viewpoint of minimizing the influence of odor due to unreacted nucleophilic agent, 75 molar equivalents or less is preferable, 60 molar equivalents or less is more preferable, and 50 molar equivalents or less is particularly preferable.

[0058] The molecular weight of the nucleophilic agent is preferably 150 or less, more preferably 110 or less, and particularly preferably 60 or less, from the viewpoint of ease of removal of unreacted nucleophilic agent.

[0059] As the reactor, known reactors such as a batch reactor and a tubular reactor can be used, but a batch reactor is preferred because there is no risk of clogging, which is a problem with tubular reactors.

[0060] From the viewpoint of reaction efficiency, the reaction temperature is preferably 10° C. or higher, more preferably 15° C. or higher, and particularly preferably 25° C. or higher. In addition, from the viewpoint of preventing side reactions such as nucleophilic reactions on the polymer main chain, the reaction temperature is preferably 80° C. or lower, more preferably 60° C. or lower, and particularly preferably 50° C. or lower.

[0061] The reaction time is preferably 1 hour or longer, more preferably 2 hours or longer, and particularly preferably 3 hours or longer from the viewpoint of reaction efficiency, and is preferably 48 hours or shorter, more preferably 36 hours or shorter, and particularly preferably 24 hours or shorter from the viewpoint of preventing side reactions such as nucleophilic reactions on the polymer main chain. The reaction pressure is usually atmospheric pressure, but may be increased or decreased as required.

[0062] When the compound having a trithiocarbonate group represented by general formula (2) does not have a structure represented by general formula (3) or a thiol group as a substituent, the structure of one terminal of the block copolymer (P2) becomes a structure represented by general formula (3) or a thiol group. On the other hand, when the compound having a trithiocarbonate group represented by general formula (2) has a structure represented by general formula (3) or a thiol group as a substituent, the structures of both terminals of the block copolymer (P2) become a structure represented by general formula (3) or a thiol group. [ka] (In the formula, R represents a residue obtained by removing an acryloyloxy group from an acrylic ester compound contained in the monomer that constitutes the block polymer (P2).)

[0063] Furthermore, at least one polymer block of the block copolymer (P2) has a (meth)acrylic acid ester compound as the main constituent monomer, at least one terminal structure of the block copolymer (P2) is a structure represented by the above general formula (3) or a thiol group, and the product of (x / 100) and y, where x is the sulfur concentration (mass%) in the block copolymer (P2) and y is the number-average molecular weight of the block copolymer (P2), is 60 or less, thereby achieving the effect of significantly reducing the odor of the cured product. The product of (x / 100) and y is preferably 57.5 or less, more preferably 55.0 or less, even more preferably 52.5 or less, and even more preferably 50.0 or less. In terms of the above effects, it is preferable to obtain the block polymer (P2) by reacting the trithiocarbonate group in the block polymer (P1) with a nucleophilic agent without purifying the block polymer (P1) by reprecipitation or the like.

[0064] 2. (Meth)acrylic polymer (II) The (meth)acrylic polymer (II) of the present invention has a weight average molecular weight of 10,000 or more and 50,000 or less, and an average number of crosslinkable silyl groups per molecule of 0.50 or more and less than 1.8. By having 0.50 or more and less than 1.8 crosslinkable silyl groups in one molecule of the (meth)acrylic polymer (II), a crosslinked structure between the (meth)acrylic polymers (II) or a crosslinked structure between the (meth)acrylic polymer (II) and the (meth)acrylic polymer (I) can be formed, and the weather resistance of the cured product of the curable resin composition can be improved.

[0065] As described above, the weight-average molecular weight (Mw) of the (meth)acrylic polymer (II) is 10,000 or more and 50,000 or less from the viewpoint of tensile properties (elongation at break, strength at break, etc.). If Mn is 10,000 or more, the weather resistance of the cured product can be excellent. If Mn is 50,000 or less, good fluidity and coatability can be ensured. From the viewpoint of the weather resistance and fluidity of the cured product, Mn of the (meth)acrylic polymer (I) is more preferably in the range of 15,000 or more and 40,000 or less, even more preferably in the range of 25,000 or more and 32,000 or less, even more preferably in the range of 26,000 or more and 30,000 or less, and even more preferably in the range of 27,000 or more and 30,000 or less.

[0066] The molecular weight distribution (Mw / Mn) obtained by dividing the weight average molecular weight (Mw) of the (meth)acrylic polymer (II) by the number average molecular weight (Mn) is, from the viewpoint of tensile properties (elongation at break, strength at break, etc.), preferably 7.8 or less, more preferably 6.0 or less, even more preferably 5.6 or less, still more preferably 5.2 or less, even more preferably 5.0 or less, and still more preferably 4.6 or less. The molecular weight distribution (Mw / Mn) is preferably 1.05 or more, and may be 1.10 or more, or may be 1.30 or more. The above Mw, Mn and Mw / Mn can be measured by the method described in the Examples.

[0067] The average number of crosslinkable silyl groups in one molecule of the (meth)acrylic polymer (II) is, as described above, 0.50 or more and less than 1.8, from the viewpoint of improving the weather resistance of the cured product. It is preferably 0.60 or more, more preferably 0.70 or more, even more preferably 0.75 or more, and even more preferably 0.78 or more. Furthermore, from the viewpoint of excellent elongation at break, it is preferably 1.3 or less, more preferably 0.90 or less, and even more preferably 0.85 or less. The average number of crosslinkable silyl groups contained in the (meth)acrylic polymer (II) having a crosslinkable silyl group is 1 It can be calculated by H-NMR measurement and GPC measurement. That is, after identifying the structural units constituting the polymer and determining the monomers used, 1 The polymer composition and the molar fraction of the crosslinkable silyl group-containing monomer are calculated from the integral of the signal at around 3.5 ppm in the H-NMR spectrum, which is derived from the hydrogen atoms bonded to the carbon atoms of the alkoxysilane. The average number of crosslinkable silyl groups per molecule can then be calculated by multiplying this molar fraction by the number-average molecular weight (Mn) obtained by GPC measurement. Here, the method for introducing the crosslinkable silyl group is not particularly limited, but for example, the crosslinkable silyl group can be introduced by copolymerizing a hydrolyzable silyl group-containing vinyl compound, and examples of the hydrolyzable silyl group-containing vinyl compound include the compounds described above.

[0068] The viscosity of the (meth)acrylic polymer (II) at 25° C. is preferably 20 Pa·s or more and 70 Pa·s or less, more preferably 35 Pa·s or more and 50 Pa·s or less. When the viscosity is 20 Pa·s or more, sagging of the curable resin composition can be prevented, and when the viscosity is 70 Pa·s or less, good fluidity and coatability of the curable resin composition can be ensured. The viscosity can be measured by the method described in the examples.

[0069] The (meth)acrylic polymer (II) may be either a random copolymer or a block copolymer, and is preferably a polymer having a structural unit derived from the above-mentioned hydrolyzable silyl group-containing vinyl compound. In addition, from the viewpoints of excellent compatibility with the (meth)acrylic polymer (I) and excellent weather resistance of the cured product of the curable resin composition, it is preferable that the curable resin composition is a polymer having a structural unit derived from a (meth)acrylic monomer.

[0070] The (meth)acrylic polymer (II) having a structural unit derived from a (meth)acrylic monomer can be obtained, for example, by polymerizing a monomer mixture containing a (meth)acrylic monomer. The (meth)acrylic monomer is a monomer having a (meth)acryloyl group in the molecule, and examples thereof include (meth)acrylic acid, the above-mentioned (meth)acrylic acid alkyl ester compound, and the compound represented by the above-mentioned general formula (1). The amount of the (meth)acrylic monomer used is preferably in the range of 10 to 100% by mass, more preferably in the range of 30 to 100% by mass, and even more preferably in the range of 50 to 100% by mass, based on the total constituent monomers of the (meth)acrylic polymer (II).

[0071] Examples of the (meth)acrylic acid alkyl ester compound include the compounds described above, and one or more of these can be used. Among these, (meth)acrylic acid alkyl esters having an alkyl group having 1 to 8 carbon atoms are preferred from the viewpoint of the tensile properties of the cured product. The amount of (meth)acrylic acid alkyl esters having an alkyl group having 1 to 8 carbon atoms used is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more, based on the total constituent monomers of the (meth)acrylic polymer (II). The upper limit is 100% by mass, and may be 90% by mass, 80% by mass, or 50% by mass.

[0072] Among the above, the use of a (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms is preferred because it ensures good compatibility with the oxyalkylene polymer and improves tensile properties and weather resistance. The number of carbon atoms in the alkyl group is preferably 10 to 20, more preferably 12 to 20. The amount of the (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms used is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, based on the total constituent monomers of the (meth)acrylic polymer (II). The upper limit is 100% by mass or less, and may be 90% by mass or less, 80% by mass or less, or 50% by mass or less.

[0073] Examples of the compound represented by general formula (1) include the compounds described above, and one or more of these can be used. Among these, from the viewpoint of the tensile properties of the cured product, (meth)acrylic acid alkoxyalkyl esters having an alkoxyalkyl group of 2 to 8 carbon atoms are preferred, and (meth)acrylic acid alkoxyalkyl esters having an alkoxyalkyl group of 2 to 4 carbon atoms are more preferred. The amount of (meth)acrylic acid alkoxyalkyl ester used is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more, based on the total constituent monomers of the (meth)acrylic polymer (II). The upper limit is 100% by mass or less, and may be 90% by mass or less, 80% by mass or less, or 50% by mass or less.

[0074] The (meth)acrylic polymer (II) may be copolymerized with other monomers copolymerizable with the above-mentioned monomers. Examples of the other monomers include the other monomers in the (meth)acrylic polymer (I), and one or more of these can be used.

[0075] 2-1. Method for producing (meth)acrylic polymer (II) The (meth)acrylic polymer (II) can be produced by conventional radical polymerization. Any of solution polymerization, bulk polymerization, and dispersion polymerization may be employed, and living radical polymerization may also be utilized. The reaction process may be any of batch, semi-batch, and continuous polymerization. Among these, high-temperature continuous polymerization at 100 to 350°C is preferred.

[0076] When crosslinkable silyl groups are uniformly introduced into a polymer, the curability of a curable resin composition containing the polymer and the physical properties of the resulting cured product, such as weather resistance, are improved. In this regard, using a stirred tank reactor as the reactor is preferred because it allows the production of a (meth)acrylic polymer (II) with a relatively narrow composition distribution (distribution of crosslinkable functional groups) and molecular weight distribution. Furthermore, a process using a continuous stirred tank reactor is more preferred in terms of narrowing the composition distribution and molecular weight distribution.

[0077] High-temperature continuous polymerization methods may be performed according to known methods disclosed in, for example, Japanese Patent Application Laid-Open Nos. 57-502171, 59-6207, and 60-215007. For example, a pressurizable reactor is filled with a solvent, set to a predetermined temperature under pressure, and then a monomer mixture consisting of each monomer and, if necessary, a polymerization solvent is fed to the reactor at a constant feed rate, and an amount of polymerization liquid corresponding to the amount of monomer mixture fed is withdrawn. A polymerization initiator may also be blended into the monomer mixture, if necessary. When blended, the amount is preferably 0.001 to 2 parts by mass per 100 parts by mass of the monomer mixture. The pressure depends on the reaction temperature and the boiling points of the monomer mixture and solvent used, and may be any pressure that does not affect the reaction but can maintain the reaction temperature. The residence time of the monomer mixture is preferably 1 to 60 minutes. If the residence time is less than 1 minute, the monomer may not react sufficiently, and if the unreacted monomer remains for more than 60 minutes, productivity may decrease. The preferred residence time is 2 to 40 minutes.

[0078] Furthermore, this method allows for easy production without the use of large amounts of impurities such as initiators and chain transfer agents for molecular weight control. It is preferable not to use chain transfer agents such as mercaptans, as this leads to a decrease in weather resistance. On the other hand, the upper limit of the polymerization temperature is preferably set to 350°C or less, since this eliminates the risk of coloration of the polymerization solution or a decrease in molecular weight due to decomposition reactions. By carrying out polymerization within the above temperature range, it is possible to efficiently produce a copolymer with an appropriate molecular weight, low viscosity, no coloration, and few impurities. In other words, this polymerization method requires only a trace amount of polymerization initiator, and does not require the use of chain transfer agents such as mercaptans or polymerization solvents, allowing for the production of a highly pure copolymer.

[0079] In addition, by producing the (meth)acrylic acid polymer (II) under high temperature conditions, A double bond can be introduced. For example, if the polymerization temperature is 100°C or higher, a cleavage reaction initiated by a hydrogen abstraction reaction from the polymer chain occurs due to the high-temperature polymerization, and a polymer having an ethylenically unsaturated bond represented by the following general formula (4) at the molecular end is obtained. The polymerization temperature is preferably 120°C or higher, and more preferably 150°C or higher. The higher the polymerization temperature, the higher the double bond concentration in the polymer tends to be. According to the above method, a (meth)acrylic polymer (II) having a double bond can be obtained simply and with good productivity.

[0080] [ka] (In the formula, M represents a monomer unit, and n is a natural number representing the degree of polymerization. R 1 represents a monovalent organic group.

[0081] R in the above general formula (4) 1 is an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group, an alkyl group which may have other substituents, a phenyl group, a benzyl group, a polyalkylene glycol group, a dialkylaminoalkyl group, a trialkoxysilylalkyl group, an alkyldialkoxysilylalkyl group, or a hydrogen atom.

[0082] Examples of polymerization initiators used to obtain the (meth)acrylic polymer (II) include any initiator that generates radicals at a predetermined reaction temperature. Specific examples include organic peroxides such as di-t-butyl peroxide, di-t-hexyl peroxide, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, cumene hydroperoxide, and t-butyl hydroperoxide, and azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), azobiscyclohexacarbonitrile, azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-amidinopropane) dihydrochloride, and 4,4'-azobis(4-cyanovaleric acid). These polymerization initiators may be used alone or in combination. When a polymerization initiator with high hydrogen abstraction ability is used, the double bond concentration of the resulting polymer tends to be high. For example, the use of an organic peroxide rather than an azo compound tends to result in a polymer with a high double bond concentration. The amount of polymerization initiator used can be adjusted appropriately depending on the types of polymerization initiator and monomer, the desired molecular weight, polymerization conditions, etc., but is generally 0.001 to 10 parts by mass per 100 parts by mass of the monomer used. When a polymer of the same molecular weight is obtained, the double bond concentration in the obtained polymer tends to increase as the amount of polymerization initiator used decreases.

[0083] When an organic solvent is used to produce the (meth)acrylic polymer (II), an organic hydrocarbon compound is suitable. Examples include cyclic ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbons such as benzene, toluene, and xylene; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and alcohols such as methanol, ethanol, and isopropanol. One or more of these can be used. Solvents that do not dissolve the (meth)acrylic acid ester copolymer well tend to cause scale growth on the reactor walls, leading to production problems during cleaning processes, etc. Furthermore, when an organic solvent with high chain transfer capacity, such as isopropanol, is used, the double bond concentration in the resulting polymer tends to be low. The amount of solvent used is preferably 80 parts by mass or less relative to 100 parts by mass of the total vinyl monomers. By using 80 parts by mass or less, a high conversion rate can be obtained in a short time. More preferably, it is 1 to 50 parts by mass. In addition, a dehydrating agent such as trimethyl orthoacetate or trimethyl orthoformate can also be added.

[0084] A known chain transfer agent may be used in the production of the (meth)acrylic polymer (II). When a chain transfer agent is used, the double bond concentration in the resulting polymer tends to be low. In addition, the double bond concentration generally decreases as the amount of the chain transfer agent used increases.

[0085] The reaction liquid withdrawn from the reactor can be directly used in the next step, or the polymer can be isolated by removing volatile components such as unreacted monomers, solvent, and low-molecular-weight oligomers by distillation, etc. A portion of the volatile components such as unreacted monomers, solvent, and low-molecular-weight oligomers distilled off from the reaction liquid can be returned to the raw material tank or directly to the reactor and reused in the polymerization reaction. Recycling the unreacted monomers and solvent is an economically preferable method. When recycling, it is necessary to determine the mixing ratio of the newly fed monomer mixture so as to maintain the desired monomer ratio and the desired amount of solvent in the reactor.

[0086] The concentration of double bonds introduced into the (meth)acrylic acid-based polymer (II) can be reduced, if necessary, by adding a radical generator and treating under heating conditions as a post-treatment of the production of the (meth)acrylic acid-based polymer (II). The amount of the radical generator added is about 0.1 to 10 parts by mass per 100 parts by mass of the polymer, and the larger the amount added, the greater the effect of reducing the double bond concentration. The heating temperature during the heat treatment is about 50 to 130°C, but the lower the temperature, the greater the effect of reducing the double bond concentration. The heating temperature is preferably in the range of 50 to 110°C, and more preferably in the range of 50 to 100°C. The heat treatment time is not particularly limited, but is preferably set so that the amount of the remaining radical generator is less than 1 mass % relative to the polymer. Those skilled in the art can calculate the amount of the remaining radicals from the activation energy, frequency factor, and reaction temperature of the radical generator used.

[0087] Furthermore, the concentration of double bonds introduced into the (meth)acrylic acid-based polymer (II) can also be reduced, if necessary, by carrying out hydrogenation as a post-treatment of the production of the (meth)acrylic acid-based polymer (II). For hydrogenation, a conventionally known method can be used. Specifically, after adding a homogeneous or heterogeneous catalyst to the polymer reaction solution, the system is conditioned with a hydrogen atmosphere, heated to a pressure of atmospheric pressure to 10 MPa and a temperature of approximately 20 to 180°C, and reacted for approximately 2 to 20 hours. Specific examples of homogeneous catalysts include rhodium complexes such as chlorotris(triphenylphosphine)rhodium, ruthenium complexes such as dichlorotris(triphenylphosphine)ruthenium and chlorohydrocarbonyltris(triphenylphosphine)ruthenium, platinum complexes such as dichlorobis(triphenylphosphine)platinum, and iridium complexes such as carbonylbis(triphenylphosphine)iridium. On the other hand, heterogeneous catalysts include solid catalysts in which transition metals such as nickel, rhodium, ruthenium, palladium, and platinum are supported on carbon, silica, alumina, fibers, organic gels, and the like. Heterogeneous catalysts are preferred because they can be easily removed by filtration or other methods, resulting in stable quality and allowing expensive catalysts to be reused. The amount of catalyst added is about 10 to 1,000 ppm relative to the vinyl polymer in the case of a homogeneous catalyst, and about 1,000 to 10,000 ppm in the case of a heterogeneous catalyst.

[0088] 3.Curable resin composition The present curable resin composition contains the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II). With respect to the respective contents, when the total of the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II) is taken as 100% by mass, the content of the (meth)acrylic polymer (I) is preferably 25 to 80% by mass, more preferably 35 to 60% by mass, and the content of the (meth)acrylic polymer (II) is preferably 20 to 75% by mass, more preferably 40 to 65% by mass. When the content of (meth)acrylic polymer (I) is 25% by mass or more, the cured product has excellent weather resistance, and when it is 80% by mass or less, good fluidity and coatability can be ensured. Also, when the content of (meth)acrylic polymer (II) is 20% by mass or more, the elongation at break of the cured product can be improved, and when it is 75% by mass or less, the cured product has excellent weather resistance.

[0089] The curable resin composition of the present invention can be used alone as an adhesive, a sealant, a paint, a coating agent, a molding material, a rubber sheet, or the like, but may also be in the form of a curable resin composition blended with other polymers having a crosslinkable silyl group, a curing accelerator, known additives, or the like, as necessary.

[0090] 3-1. Other polymers having crosslinkable silyl groups Other polymers having a crosslinkable silyl group include polyoxyalkylene polymers having a crosslinkable silyl group, (meth)acrylic polymers having a crosslinkable silyl group (however, different from the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II)), polyester polymers having a crosslinkable silyl group, polyurethane polymers having a crosslinkable silyl group, polybutadiene polymers having a crosslinkable silyl group, hydrogenated polybutadiene polymers having a crosslinkable silyl group, and polyisobutylene polymers having a crosslinkable silyl group. Among these, when the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II) each contain a (meth)acrylic acid ester compound as a main constituent monomer, a polyoxyalkylene polymer (III) having a crosslinkable silyl group is preferred from the viewpoints of excellent compatibility, excellent tensile properties of the cured product, and excellent weather resistance.

[0091] The polyoxyalkylene polymer (III) having a crosslinkable functional group is not particularly limited as long as it contains a repeating unit represented by the following general formula (5). -OR 1 - (5) (In the formula, R 1 is a divalent hydrocarbon group. R in the above general formula (5) 1 Examples of such are as follows: (CH2) n (n is an integer between 1 and 10) CH(CH3)CH2 CH(C2H5)CH2 C(CH3)2CH2 The polyoxyalkylene polymer (III) may contain one or a combination of two or more of the repeating units. Among these, CH(CH3)CH2 is preferred from the viewpoint of excellent workability.

[0092] The crosslinkable silyl group contained in the polyoxyalkylene polymer (III) is not particularly limited, and examples thereof include an alkoxysilyl group, a halogenosilyl group, a silanol group, etc., but an alkoxysilyl group is preferred in terms of ease of controlling reactivity. Specific examples of the alkoxysilyl group include a trimethoxysilyl group, a methyldimethoxysilyl group, a dimethylmethoxysilyl group, a triethoxysilyl group, a methyldiethoxysilyl group, and a dimethylethoxysilyl group.

[0093] The method for producing the polyoxyalkylene polymer (III) is not particularly limited, and examples thereof include a polymerization method using an alkali catalyst such as KOH, a polymerization method using a transition metal compound-porphyrin complex catalyst, a polymerization method using a composite metal cyanide complex catalyst, and a polymerization method using phosphazene, using a corresponding epoxy compound or diol as a raw material. The polyoxyalkylene polymer may be either a linear polymer or a branched polymer, or a combination of these may be used.

[0094] The average number of crosslinkable silyl groups contained in one molecule of the polyoxyalkylene polymer (III) is preferably in the range of 1 to 4, more preferably 1.5 to 3, from the viewpoints of the tensile properties and adhesiveness of the cured product. The position of the crosslinkable silyl group contained in the polyoxyalkylene polymer (III) is not particularly limited, and it can be located in the side chain and / or at the end of the polymer. The polyoxyalkylene polymer (III) may be either a linear polymer or a branched polymer, or a combination of these may be used.

[0095] The number average molecular weight (Mn) of the polyoxyalkylene polymer (III) is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 15,000 or more, from the viewpoint of tensile properties. Mn may be 18,000 or more, 22,000 or more, or even 25,000 or more. From the viewpoint of workability (viscosity) during application of the curable resin composition, the upper limit of Mn is preferably 60,000 or less, more preferably 50,000 or less, and even more preferably 40,000 or less. The range of Mn can be set by combining the above upper and lower limits, and may be, for example, 5,000 or more and 60,000 or less, 15,000 or more and 60,000 or less, 18,000 or more and 50,000 or less, or 22,000 or more and 50,000 or less.

[0096] Commercially available products may be used as the polyoxyalkylene polymer (III). Specific examples include "MS Polymer S203," "MS Polymer S303," "MS Polymer S810," "Silyl SAT200," "Silyl SAT350," "Silyl EST280," and "Silyl SAT30" manufactured by Kaneka Corporation, and "Excestar ES-S2410," "Excestar ES-S2420," and "Excestar ES-S3430" (all trade names) manufactured by AGC.

[0097] 3-2.Curing accelerator In order to produce a cured product using the curable resin composition of the present invention, a curing accelerator (a component that accelerates the moisture curing reaction) is usually blended. Examples of the curing accelerator include organic tin compounds, organic titanium compounds, organic aluminum compounds, organic zirconium compounds, organic iron compounds, organic vanadium compounds, amine compounds, acidic phosphate esters, reaction products of acidic phosphate esters and amine compounds, saturated or unsaturated polycarboxylic acids and their acid anhydrides, and reaction products (salts, etc.) of carboxylic acid compounds and amine compounds. Among these, organic tin compounds are preferred. The curable resin composition of the present invention may contain only one type of curing accelerator, or two or more types.

[0098] Examples of organic tin compounds include dibutyltin dicarboxylates such as dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate, dioctyltin maleate, dibutyltin phthalate, and dibutyltin bis(alkylmaleate); divalent tin carboxylates such as tin octoate, tin oleate, tin stearate, tin naphthenate, tin stearate, and tin versatate; alkoxide derivatives of dialkyltin such as dibutyltin dimethoxide and dibutyltin diphenoxide; intramolecularly coordinating derivatives (chelate compounds) of dialkyltin such as dibutyltin diacetylacetonate and dibutyltin acetoacetate; reaction products of dibutyltin oxide and an ester compound, such as the reaction product of dibutyltin oxide and a phthalate ester; and reaction products of dibutyltin oxide and a silicate compound.

[0099] Examples of organic titanium compounds include titanium alkoxides such as tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and tetra(2-ethylhexyl titanate); chelate compounds such as titanium tetraacetylacetonate and titanium ethylacetoacetate; and triethanolamine titanate.

[0100] Examples of the organoaluminum compound include aluminum alkoxides such as aluminum isopropylate, monosec-butoxyaluminum diisopropylate, and aluminum sec-butylate; and chelate compounds such as aluminum trisacetylacetonate, aluminum trisethylacetoacetate, and diisopropoxyaluminum ethylacetoacetate.

[0101] Examples of organic zirconium compounds include zirconium alkoxides such as zirconium tetraisopropoxide and zirconium tetrabutoxide; and chelate compounds such as zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium tetraacetylacetonate, zirconium acetylacetonate bisethylacetoacetate, and zirconium acetate.

[0102] Examples of organic iron compounds include iron carboxylates such as iron 2-ethylhexanoate (divalent), iron 2-ethylhexanoate (trivalent), iron neodecanoate (divalent), iron neodecanoate (trivalent), iron oleate (divalent), iron oleate (trivalent), iron naphthenate (divalent), and iron naphthenate (trivalent).

[0103] Examples of the amine compound include butylamine, octylamine, laurylamine, dibutylamine, monoethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, oleylamine, cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, dibutylamine-2-ethylhexoate, guanidine, diphenylguanidine, 2,4,6-tris(dimethylaminomethyl)phenol, morpholine, N-methylmorpholine, 2-ethyl-4-methylimidazole, and 1,8-diazabicyclo(5,4,0)undecene-7 (DBU).

[0104] The content of the curing accelerator in the curable resin composition of the present invention is not particularly limited, and the content of the curing accelerator is preferably 0.25 to 2.5 parts by mass, more preferably 0.5 to 1.5 parts by mass, based on 100 parts by mass of the total of the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II). The content of the curing accelerator is preferably 0.16 to 1.6 parts by mass, more preferably 0.3 to 1.0 part by mass, when the total of the (meth)acrylic polymer (I), the (meth)acrylic polymer (II), and the oxyalkylene polymer (III) having a crosslinkable silyl group is taken as 100 parts by mass.

[0105] 3-3.Additives The curable resin composition of the present invention may contain conventionally known additives depending on the purpose, application, etc. Examples of additives include fillers, plasticizers, antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, flame retardants, antifoaming agents, lubricants, weather resistance stabilizers, tackifiers, anti-sagging agents, anti-tacking agents, dehydrating agents, conductivity imparting agents, antistatic agents, water repellents, oil repellents, preservatives, colorants (pigments, dyes, etc.), and fluorescent brighteners.

[0106] Examples of fillers include light calcium carbonate (average particle size of about 0.02 to 2.0 μm), heavy calcium carbonate (average particle size of about 1.0 to 5.0 μm), titanium oxide, carbon black, synthetic silicic acid, talc, zeolite, mica, silica, calcined clay, kaolin, bentonite, aluminum hydroxide, barium sulfate, glass balloons, silica balloons, and polymethyl methacrylate balloons.

[0107] Examples of plasticizers include liquid polyurethane resins, polyester-based plasticizers obtained from dicarboxylic acids and diols; etherified or esterified products of polyalkylene glycols such as polyethylene glycol and polypropylene glycol; polyether-based plasticizers such as sugar-based polyethers obtained by addition polymerization of alkylene oxides such as ethylene oxide and propylene oxide to a sugar polyhydric alcohol such as sucrose, followed by etherification or esterification; polystyrene-based plasticizers such as poly-α-methylstyrene; and poly(meth)acrylates without crosslinkable functional groups. Among these, poly(meth)acrylates without crosslinkable functional groups are preferred in terms of durability, such as weather resistance, of the cured product. Among these, those with an Mw in the range of 1,000 to 7,000 and a glass transition temperature of −30° C. or lower are more preferred. The amount of the plasticizer used is preferably in the range of 0 to 100 parts by mass, may be in the range of 0 to 80 parts by mass, or may be in the range of 0 to 50 parts by mass, relative to 100 parts by mass of the total amount of the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II).

[0108] Examples of fillers include light calcium carbonate with an average particle size of about 0.02 to 2.0 μm, heavy calcium carbonate with an average particle size of about 1.0 to 5.0 μm, titanium oxide, carbon black, synthetic silicic acid, talc, zeolite, mica, silica, calcined clay, kaolin, bentonite, aluminum hydroxide, barium sulfate, glass balloons, silica balloons, and polymethyl methacrylate balloons. These fillers improve the mechanical properties of the cured product, and can increase its breaking strength and breaking elongation. Among these, light calcium carbonate, heavy calcium carbonate, and titanium oxide are preferred, as they are highly effective in improving physical properties, and a mixture of light calcium carbonate and heavy calcium carbonate is more preferred. The amount of filler added is preferably 20 to 300 parts by mass, more preferably 50 to 200 parts by mass, per 100 parts by mass of the polyoxyalkylene polymer and the present block copolymer combined. When a mixture of light calcium carbonate and heavy calcium carbonate is used as described above, the mass ratio of light calcium carbonate to heavy calcium carbonate is preferably in the range of 90 / 10 to 50 / 50.

[0109] Examples of the antioxidant include hindered phenol compounds, monophenol compounds, bisphenol compounds, and polyphenol compounds. Examples of ultraviolet absorbers include benzophenone compounds, benzotriazole compounds, salicylate compounds, substituted tolyl compounds, and metal chelate compounds. Examples of the light stabilizer include benzotriazole compounds, hindered amine compounds, and benzoate compounds. In the present invention, an antioxidant, an ultraviolet absorber, and a light stabilizer or a heat stabilizer can be used in appropriate combination as an antiaging agent.

[0110] Examples of adhesion promoters include alkoxysilanes having an amino group or a substituted amino group, such as 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, γ-(N-trimethylsilyl)-3-aminopropyltrimethoxysilane, and 1,1-dimethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane. Commercially available alkoxysilanes may be used, including, for example, aminosilanes (all trade names) manufactured by Shin-Etsu Silicones Co., Ltd., such as "KBM602," "KBM603," "KBE602," "KBE603," "KBM902," and "KBM903."

[0111] Examples of the dehydrating agent include methyl orthoformate, methyl orthoacetate, vinyltrimethoxysilane, vinylmethyldimethoxysilane, tetraethoxysilane, and tetramethoxysilane.

[0112] Other thermoplastic resins may be added to the curable resin composition for the purpose of adjusting its performance, coatability, processability, etc. Specific examples of thermoplastic resins include polyolefin resins such as polyethylene and polypropylene, styrene resins such as polystyrene, vinyl resins such as polyvinyl chloride, polyester resins, polyamide resins, etc. Also, known elastomers may be added and mixed.

[0113] 3-4. Use of the curable resin composition The viscosity at 25°C of the curable resin composition used to form a cured product is preferably 10 to 400 Pa·s, more preferably 10 to 250 Pa·s, even more preferably 15 to 200 Pa·s, and still more preferably 20 to 160 Pa·s. The viscosity can be measured by the method described in the examples. The curable resin composition of the present invention exhibits good fluidity at room temperature (25°C), and can be applied to a variety of coating processes as well as molding processes using various methods such as extrusion molding, injection molding, and slip casting.

[0114] In the present invention, the curable resin composition containing a curing accelerator can be easily cured at a sufficient rate by atmospheric moisture or the like. A three-dimensional crosslinked structure is formed, and a cured product having rubber-like elasticity can be obtained. Therefore, the curable resin composition of the present invention is useful as an adhesive, a sealant, a paint, a coating agent, a molding material, a rubber sheet, or the like that forms such a cured product in the fields of architecture, civil engineering, electrical and electronics, and vehicles. When the curable resin composition of the present invention is used as it is to form a cured product, it can be used as a one-component type in which all components are mixed in advance and stored in a sealed container, which is opened when used, and after application, the composition is cured by absorbing moisture in the air. Alternatively, it can be used as a two-component type in which a curing agent composition containing a curing accelerator and the like is prepared separately from the (meth)acrylic polymer (I), the (meth)acrylic polymer (II), and the oxyalkylene polymer (III) having a crosslinkable silyl group, and all components are mixed when used.

[0115] The sealant composition of the present invention can have the configuration of the curable resin composition of the present invention described above, and can be used, for example, in a method of filling a gap between one adherend (hereinafter also referred to as a "first adherend") and another adherend (hereinafter also referred to as a "second adherend") placed adjacent to the first adherend with a gap therebetween. The constituent materials of the first adherend and the second adherend may be the same or different and may be, for example, ceramics, metal, concrete, glass, etc. The cured product obtained by the present invention has excellent weather resistance and is therefore suitable for applications in which it will be exposed outdoors for long periods of time. [Example]

[0116] The present disclosure will be specifically described below based on examples. However, the present disclosure is not limited to these examples. In the following, "parts" and "%" mean parts by mass and % by mass unless otherwise specified. The analytical methods for the (meth)acrylic polymers obtained in the Synthesis Examples, Comparative Synthesis Examples, Production Examples and Comparative Production Examples are described below.

[0117] <Molecular weight measurement> The resulting (meth)acrylic polymer was subjected to gel permeation chromatography (GPC) under the conditions described below to obtain the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene. The molecular weight distribution (Mw / Mn) was calculated from the obtained values. Measurement conditions Device: Tosoh Corporation, model name "HLC-8320" Column: Tosoh TSKgel SuperMultiporeHZ-M x 4 Solvent: tetrahydrofuran Column temperature: 40℃ Detector: RI Flow rate: 600μL / min

[0118] <Gas chromatography (GC) measurement> Measurement conditions Columns: Capillary columns Agilent CP-Wax52CB (60 m × 0.32 mm ID, df = 0.5 μm) and Agilent DB-1 (30 m × 0.32 mm ID, df = 1.0 μm) Solvent: tetrahydrofuran Column temperature: 50°C (5 min), 7°C / min, 230°C (5 min)

[0119] <Viscosity measurement> The E-type viscosity was measured using a TVE-20H viscometer (cone / plate type, manufactured by Toki Sangyo Co., Ltd.) under the following conditions. Measurement conditions Cone shape No. 1: Angle 1°34′, radius 24 mm (less than 10,000 mPa·s) No.7: Angle 3°, radius 7.7mm (10,000mPa s or more) ·Temperature: 25℃±0.5℃ Rotation speed: No.1: 1.0 rpm No. 7: If the viscosity is 100,000 mPa·s or more, run at 1.5 rpm If the viscosity is 100,000 mPa·s or less, 10 rpm

[0120] <Average number of crosslinkable silyl groups per (meth)acrylic polymer molecule> The average number of crosslinkable silyl groups (alkoxysilyl groups) (hereinafter also referred to as "f(Si)") was calculated using the following formula from the parts by mass of monomers having crosslinkable silyl groups when the total number of constituent monomers was taken as 100 parts by mass. f(Si) = {parts by mass of crosslinkable silyl group-containing monomer / (molecular weight of crosslinkable silyl group-containing monomer × 100 / Mn)}

[0121] <Preparation and Evaluation Methods of Curable Resin Compositions in Examples and Comparative Examples> Each component was blended according to the blending ratio shown in Table 1 below, and a curable resin composition was prepared according to a conventional method.

[0122] [Table 1]

[0123] The abbreviations for the compounds in Table 1 have the following meanings. Polyoxyalkylene polymer: Branched modified silicone Exestar ES-S3430 (AGC) UP-1110: Acrylic plasticizer, ARUFON (registered trademark) UP-1110 (manufactured by Toagosei Co., Ltd.) Precipitated calcium carbonate: Hakuenka CCR (Shiraishi Calcium Co., Ltd.) Heavy calcium carbonate: Super SS (Maruo Calcium Co., Ltd.) R820: Titanium oxide R-820 (manufactured by Ishihara Sangyo Kaisha) B75: Anti-aging agent, Tinuvin B75 (manufactured by Ciba Specialty Co., Ltd.) SH6020: 3-(2-aminoethylamino)propyltrimethoxysilane, SH6020 (manufactured by Dow Corning Toray Co., Ltd.) S340: N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)propanamine, SilaAce S340 (JNC Corporation) SZ6300: Vinyltrimethoxysilane, SZ6300 (manufactured by Dow Corning Toray Co., Ltd.) U-220H: Tin catalyst (dibutyltin diacetylacetonate), Neostan U-220H (manufactured by Nitto Kasei Co., Ltd.) In addition, the abbreviations Wx and Wy in Table 1 represent the number of parts of triblock copolymer X and copolymer Y, respectively.

[0124] <Tensile test> Each curable resin composition was applied to a Teflon (registered trademark) sheet at room temperature (25°C) to a thickness of 2 mm, and cured for one week under conditions of 23°C and 50% RH to prepare a cured sheet. Test pieces were punched out from the cured sheets using a tensile dumbbell (JIS K 6251 No. 3), and the breaking strength (MPa) and breaking elongation (%) were measured using a tensile tester (Autograph AGS-J, manufactured by Shimadzu Corporation) at a temperature of 23°C and a humidity of 50% at a tension speed of 200 mm / min.

[0125] <Weather resistance test> Each curable resin composition was applied to a Teflon (registered trademark) sheet at room temperature (25°C) to a thickness of 2 mm, and cured for one week under conditions of 23°C and 50% RH to prepare a cured sheet. The cured sheet was placed in a metaling weather meter (DAIPLA METAL WEATHER KU-R5NCI-A manufactured by Daipla Wintes) and subjected to an accelerated weathering test under irradiation conditions of 63°C, 70% RH, and 80 mW / cm irradiance. 2 The test was conducted with a two-minute shower once every two hours. The time when abnormalities such as cracks and bleeding began to appear on the exterior was recorded, and the weather resistance was evaluated.

[0126] <<Production of (meth)acrylic polymer (triblock copolymer X in Table 1)>> <Production of polymer block (A)> (Synthesis Example 1: Production of Polymer a-1) A 1 L flask equipped with a stirrer and thermometer was charged with S,S-dibenzyl trithiocarbonate (hereinafter also referred to as "DBTTC") (6.4 parts), 2,2'-azobis(2,4-dimethylvaleronitrile) (hereinafter also referred to as "V-65") (0.28 parts), n-butyl acrylate (hereinafter also referred to as "nBA") (56 parts), ethyl acrylate (hereinafter also referred to as "EA") (4.0 parts), tetradecyl acrylate (hereinafter also referred to as "TDA") (15 parts), methyldimethoxysilylpropyl methacrylate (25 parts), ethyl acetate (85 parts), and trimethyl orthoacetate (hereinafter also referred to as "MOA") (21 parts), thoroughly degassed with nitrogen bubbling, and heated to 58 ° C to initiate polymerization. After 2 hours, the temperature was raised to 70 ° C over 1 hour, and the reaction was continued for another 4 hours at 70 ° C. Thereafter, the reaction was stopped by cooling to room temperature, and a solution containing polymer a-1 was obtained. The molecular weight of the obtained polymer a-1 was Mn 4,600, Mw 6,800, and Mw / Mn 1.48 as measured by GPC (gel permeation chromatography) (based on polystyrene). The reaction rates of each monomer measured by gas chromatography (GC) were nBA: 80%, EA: 89%, TDA: 83%, and methyldimethoxysilylpropyl methacrylate: 100%.

[0127] (Synthesis Examples 2 to 10 and Comparative Synthesis Examples 1 to 3: Production of Polymers a-2 to a-10 and a'-1 to a'-3) Polymers a-2 to a-10 and a'-1 to a'-3 were obtained in the same manner as in Synthesis Example 1, except that the raw materials used were as shown in Table 2. The molecular weight of each polymer and the reaction rate of each monomer were measured and are shown in Table 2.

[0128] [Table 2]

[0129] In Table 2, the abbreviations other than those described in Synthesis Example 1 refer to the following compounds. MMA: Methyl methacrylate

[0130] <Production of triblock copolymer> (Synthesis Example 11: Production of triblock copolymer b-1) A 1 L flask equipped with a stirrer and a thermometer was charged with the solution containing polymer a-1 obtained in Synthesis Example 1 (8.7 parts), nBA (68.3 parts), EA (4.6 parts), TDA (18.4 parts), ABN-E (0.21 parts), ethyl acetate (42 parts) and MOA (11 parts), and the mixture was thoroughly degassed by nitrogen bubbling, and polymerization was initiated in a thermostatic bath at 70 ° C. Six hours after the start of polymerization, the reaction was stopped by cooling to room temperature, and a solution containing triblock copolymer b-1 was obtained. The molecular weight of the obtained triblock copolymer b-1 was Mn 45,000, Mw 51,000, and Mw / Mn 1.13. The reaction rates of each monomer measured by gas chromatography (GC) were nBA: 91%, EA: 90%, and TDA: 88%.

[0131] (Synthesis Examples 12, 15 to 20 and Comparative Synthesis Examples 4 to 5: Production of Triblock Polymers b-2, b-5 to b-10, b'-1 and b'-2) Triblock copolymers b-2 to b-10 and b'-1 and b'-2 were obtained by the same procedure as in Synthesis Example 11, except that the raw materials used were as shown in Table 3. The molecular weight of each polymer and the reaction rate of each monomer were measured and are shown in Table 3.

[0132] Synthesis Example 13: Preparation of triblock copolymer b-3 A 1 L flask equipped with a stirrer and thermometer was charged with a solution containing polymer a-3 (2.8 parts) obtained in Synthesis Example 3, nBA (22.2 parts), MMA (1.47 parts), TDA (5.89 parts), ABN-E (0.064 parts), ethyl acetate (14 parts), and MOA (3.58 parts). The mixture was thoroughly degassed by nitrogen bubbling, and polymerization was initiated in a thermostatic bath at 70 ° C. A monomer mixture solution obtained by stirring and mixing nBA (44.4 parts), MMA (2.93 parts), and TDA (11.8 parts), and polymer a-3 (8.5 parts) obtained in Synthesis Example 3 were continuously fed into the flask over 240 minutes, starting 30 minutes after the start of polymerization. After the continuous feed was completed, a mixed solution of ABN-E (0.056 parts) and ethyl acetate (1.0 part) was fed, and the internal temperature was raised to 60 ° C. over 30 minutes. Seven hours after the start of polymerization, the reaction was stopped by cooling to room temperature, and a solution containing triblock copolymer b-3 was obtained. The molecular weight of the obtained triblock copolymer b-3 was Mn 61,000, Mw 88,000, and Mw / Mn 1.44. The reaction rates of each monomer measured by gas chromatography (GC) were nBA: 92%, MMA: 100%, and TDA: 93%.

[0133] Synthesis Example 14: Preparation of triblock polymer b-4 The same procedure as in Synthesis Example 13 was carried out to obtain a triblock copolymer b-4, except that the raw materials used were as shown in Table 3. The molecular weight of each polymer and the reaction rate of each monomer were measured and are shown in Table 3.

[0134] Comparative Synthesis Example 6: Preparation of Triblock Copolymer b'-3 A 1 L flask equipped with a stirrer and thermometer was charged with a solution containing polymer a'-3 (2.8 parts) obtained in Synthesis Example 3, nBA (22.2 parts), MMA (1.47 parts), TDA (5.83 parts), ABN-E (0.064 parts), ethyl acetate (14 parts), and MOA (3.58 parts). The mixture was thoroughly degassed by nitrogen bubbling, and polymerization was initiated in a thermostatic bath at 70 ° C. Thirty minutes after the start of polymerization, a monomer mixture solution obtained by stirring and mixing nBA (44.6 parts), MMA (2.93 parts), and TDA (11.7 parts) and polymer a'-3 (8.5 parts) obtained in Synthesis Example 3 were continuously fed into the flask over 480 minutes. After the completion of the continuous feed, a mixed solution of ABN-E (0.056 parts) and ethyl acetate (1.0 part) was fed, and the internal temperature was raised to 60 ° C. over 30 minutes. After 11 hours from the start of polymerization, the reaction was stopped by cooling to room temperature to obtain a solution containing triblock copolymer b'-3. The molecular weights of the obtained triblock copolymer b'-3 were Mn 76,000, Mw 174,000, and Mw / Mn 2.29. The conversion rates of each monomer measured by gas chromatography (GC) were nBA: 83%, MMA: 99%, and TDA: 86%.

[0135] [Table 3]

[0136] In Table 3, the abbreviations other than those described in Synthesis Example 1 refer to the following compounds. MMA: Methyl methacrylate

[0137] <Production of Pentablock Copolymer> Synthesis Example 21: Preparation of pentablock copolymer c-1 To the solution (98.9 parts) containing the triblock copolymer b-1 obtained in Synthesis Example 11, methyldimethoxysilylpropyl methacrylate (1.1 parts), ABN-E (0.038 parts), and MOA (0.21 parts) were added, thoroughly degassed by nitrogen bubbling, and the temperature was raised to 60 °C to initiate polymerization. After 7 hours, the reaction was stopped by cooling to room temperature, yielding a solution containing pentablock copolymer c-1. The molecular weight of the pentablock copolymer c-1 was Mn 50,000, Mw 60,000, and Mw / Mn 1.20. The conversion rates of each monomer measured by gas chromatography (GC) were nBA: 81%, EA: 89%, TDA: 86%, and methyldimethoxysilylpropyl methacrylate: 99%. The obtained pentablock copolymer c-1 had a polymer block (A) consisting of nBA, EA, TDA, and methyldimethoxysilylpropyl methacrylate, and a polymer block (B) consisting of nBA, EA, and TDA, and was a pentablock copolymer with a block structure of (A)-(B)-(A)-(B)-(A). Based on the polymerization rate, the composition ratio of polymer block (A) to polymer block (B) was (A) / (B) / (A) / (B) / (A) = 1.7 / 43.6 / 9.4 / 43.6 / 1.7 (wt%), which means that (A) / (B) was approximately 13 / 87 (wt%).

[0138] (Synthesis Examples 22 to 30 and Comparative Synthesis Examples 7 to 9: Preparation of Pentablock Copolymers c-2 to c-10 and c'-1 to c'-3) Pentablock copolymers c-2 to c-10 and c'-1 to c'-3 were obtained by the same procedure as in Synthesis Example 21, except that the raw materials used were as shown in Table 3. The molecular weights of the polymers were measured and are shown in Table 4. The composition ratios of polymer block (A) and polymer block (B) were calculated and are shown in Table 4.

[0139] [Table 4]

[0140] <Post-treatment step of pentablock copolymers c-1 to c-10 and c'-1 to c'-3> (Production Example 1: Production of triblock copolymer d-1) The solution containing block copolymer c-1 obtained in Synthesis Example 21 was thoroughly degassed by bubbling with nitrogen, and then n-propylamine (5 molar equivalents relative to the thiocarbonylthio groups of block copolymer c-1) was added, and the decomposition reaction of the thiocarbonyl groups was initiated in a thermostatic bath at 40° C. After 5 hours, the reaction was stopped by cooling to room temperature, yielding a solution containing block copolymer d-1. The solution was decompressed to 20 kPa and volatile components such as unreacted monomers and solvents were continuously distilled off using a thin-film evaporator maintained at 120°C, and the non-volatile component, block copolymer d-1, was recovered. The block copolymer d-1 obtained as the (meth)acrylic polymer (I) is a triblock copolymer having an (A)-(B)-(A) structure, consisting of polymer blocks (A) - a copolymer block of n-butyl acrylate, tetradecyl acrylate, ethyl acrylate, and methyldimethoxysilylpropyl methacrylate, and (B) - a copolymer block of n-butyl acrylate, tetradecyl acrylate, and ethyl acrylate, and is a Michael adduct of a thiol formed by decomposition of the thiocarbonylthio group of the block copolymer c-1 with an amine and the remaining acrylate compound contained in the block copolymer c-1. 1 From the H-NMR measurement, it was confirmed that the peak (4.8 ppm) of hydrogen bonded to the carbon adjacent to the thiocarbonylthio group, which was observed in the block copolymer c-1, disappeared in the block copolymer d-1, and peaks (3.3 ppm, 2.9 ppm) derived from a Michael adduct with the remaining acrylate compound (terminal molecular structure represented by the above general formula (3)) appeared. The molecular weight of block copolymer d-1 was Mn 32,000, Mw 40,000, and Mw / Mn 1.25. The average number of crosslinkable silyl groups per molecule in block (A) was calculated to be 5.0 from the amount of dimethoxysilylpropyl methacrylate introduced per RAFT agent. Furthermore, the E-type viscosity was 190 Pa·s.

[0141] (Production Examples 2 to 10 and Comparative Examples 1 to 3: Production of Triblock Copolymers d-2 to d-10 and d'-1 to d'-3) The raw materials used were as shown in Table 5, and the same procedure as in Production Example 1 was carried out except that the desolvation temperature was appropriately adjusted, to obtain block copolymers d-2 to d-10 and d'-1 to d'-3. Table 5 shows the molecular weight and polymer composition of each block copolymer, the average number of crosslinkable silyl groups per molecule contained in block (A), and the E-type viscosity.

[0142] [Table 5]

[0143] The abbreviations of the compounds shown in Table 5 represent the following compounds. PAm: n-propylamine

[0144] <<Production of (meth)acrylic polymer (copolymer Y in Table 1)>> (Production Example 11: Production of Copolymer Y-1) The temperature of a 1000 mL oil-jacketed pressurized stirred tank reactor was maintained at 192°C. Next, while maintaining the pressure of the reactor constant, a monomer mixture consisting of 75.8 parts nBA, 20 parts TDA, 4.2 parts vinyldimethoxysilane (hereinafter also referred to as "VDMS"), 3.0 parts isopropyl alcohol (hereinafter also referred to as "IPA"), 3.0 parts MOA, 4.0 parts methyl ethyl ketone (hereinafter also referred to as "MEK"), and 0.02 parts di-t-hexyl peroxide (NOF Corp., trade name "Perhexyl D", hereinafter also referred to as "DTHP") as a polymerization initiator was continuously fed from a raw material tank to the reactor at a constant feed rate (48 g / min, residence time: 12 min), and a reaction liquid equivalent to the amount of the monomer mixture fed was continuously withdrawn from the outlet. Immediately after the start of the reaction, the reaction temperature dropped once, and then a temperature rise due to the heat of polymerization was observed, but the reaction temperature was maintained at 191 to 193°C by controlling the temperature of the oil jacket. The point at which the temperature stabilized after the start of the monomer mixture supply was designated as the start point for collecting the reaction solution, and the reaction was continued for 25 minutes from this point. As a result, 1.2 kg of the monomer mixture was supplied and 1.2 kg of the reaction solution was collected. The reaction solution was then introduced into a thin-film evaporator, and volatile components such as unreacted monomers were separated to obtain copolymer Y-1 as a (meth)acrylic polymer (II).

[0145] <Calculation of the composition of copolymer Y> The volatile components were measured by gas chromatography (GC) to calculate the content of each component. The composition of copolymer Y was determined by subtracting the amount of the volatile components from the amount of each component supplied.

[0146] (Production Examples 12 to 19 and Comparative Production Examples 4 to 7) The polymers were synthesized in the same manner as in Production Example 11, except that the raw materials were charged as shown in Table 6 and the temperature inside the reactor was appropriately adjusted. The molecular weight and polymer composition of each polymer, the average number of crosslinkable silyl groups per molecule, and the E-type viscosity are shown in Table 6.

[0147] [Table 6]

[0148] <Preparation and Evaluation of Curable Resin Composition> (Examples 1 to 22 and Comparative Examples 1 to 9) Using the triblock copolymers X obtained in Production Examples 1 to 10 and Comparative Production Examples 1 to 3, and the copolymers Y obtained in Production Examples 11 to 19 and Comparative Production Examples 1 to 3 as base resins, curable resin compositions were prepared according to the above-mentioned recipes (Table 1) and Tables 7 to 9, and cured sheets were produced from each of the compositions. The cured sheets obtained from each curable resin composition were subjected to a tensile test and a weather resistance test. The results are shown in Tables 7-9.

[0149] [Table 7]

[0150] [Table 8]

[0151] [Table 9]

[0152] <Evaluation Results> As is clear from the results of Examples 1 to 22, the cured products of the curable resin compositions of the present invention had excellent coatability, high elongation at break, excellent tensile properties, and excellent weather resistance. Among these, when focusing on the content of (meth)acrylic polymer (I), the higher the content, the better the weather resistance of the cured product (Examples 3, 11 to 14).Furthermore, when focusing on the content of (meth)acrylic polymer (II), the higher the content, the higher the elongation at break of the cured product and the more excellent the tensile properties (Examples 3, 11 to 14).

[0153] In contrast to these, when the (meth)acrylic polymer (II) was not contained (Comparative Example 1), and when the average number of crosslinkable silyl groups per molecule of the (meth)acrylic polymer (II) was 1.8 or more (Comparative Example 9), the breaking elongation was low. Furthermore, when no (meth)acrylic polymer (I) was contained (Comparative Example 2), when the average number of crosslinkable silyl groups per molecule of the (meth)acrylic polymer (I) was less than 1.8 (Comparative Example 3), when the number average molecular weight of the (meth)acrylic polymer (I) was less than 30,000 (Comparative Example 4), when the weight average molecular weight of the (meth)acrylic polymer (II) was less than 10,000 (Comparative Example 6), and when the average number of crosslinkable silyl groups per molecule of the (meth)acrylic polymer (II) was less than 0.50 (Comparative Example 8), the weather resistance was significantly poor and the composition was not suitable for practical use. Furthermore, when the (meth)acrylic polymer (II) was not contained (Comparative Example 1), when the molecular weight distribution of the (meth)acrylic polymer (I) was 2.2 or more (Comparative Example 5), and when the weight average molecular weight of the (meth)acrylic polymer (II) was more than 50,000 (Comparative Example 7), the viscosity of the composition exceeded 400 Pa s, resulting in poor coatability. [Industrial Applicability]

[0154] The curable resin composition of the present invention has excellent coatability, and can give a cured product having high elongation at break, excellent tensile properties, and excellent weather resistance. Therefore, the composition can be used as an adhesive, a sealant, a paint, a coating agent, a molding material, a rubber sheet, etc., and is particularly suitable for use as a sealant because of its excellent weather resistance.

Claims

1. The polymer comprises a (meth)acrylic polymer (I) having a number average molecular weight of 30,000 or more and 80,000 or less, a molecular weight distribution (Mw / Mn) of 2.2 or less, and an average number of crosslinkable silyl groups per molecule of 1.8 or more, and a (meth)acrylic polymer (II) having a weight average molecular weight of 10,000 or more and 50,000 or less, and an average number of crosslinkable silyl groups per molecule of 0.50 or more and less than 1.8, the (meth)acrylic polymer (I) is a block copolymer having a structural unit consisting of polymer block (A) / polymer block (B) / polymer block (A), At least one polymer block of the block copolymer contains a structural unit derived from an acrylic acid ester compound, At least one terminal structure of the block copolymer is a structure represented by the following general formula (3): 【Chemistry 1】 (In the formula, R represents a residue obtained by removing an acryloyloxy group from an acrylic ester compound contained in the monomer that constitutes the block polymer.)

2. 2. The curable resin composition according to claim 1, wherein the (meth)acrylic polymer (I) contains a structural unit derived from a (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms.

3. 3. The curable resin composition according to claim 1, wherein the (meth)acrylic polymer (II) contains a structural unit derived from a (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms.

4. 4. The curable resin composition according to claim 1, wherein the content of the (meth)acrylic polymer (I) is 25 to 80 mass% and the content of the (meth)acrylic polymer (II) is 20 to 75 mass%, where the total of the (meth)acrylic polymer (I) and the (meth)acrylic polymer (II) is 100 mass%.

5. The curable resin composition according to any one of claims 1 to 4, further comprising an oxyalkylene polymer (III) having a crosslinkable silyl group.

6. The curable resin composition according to any one of claims 1 to 5, having a viscosity at 25°C of 100 to 400 Pa·s.

7. A sealant composition comprising the curable resin composition according to any one of claims 1 to 6.

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