Method for producing vinyl polymer

Abstract

To provide a method for producing a vinyl polymer, which can produce a vinyl polymer having a sufficiently narrow molecular weight distribution.SOLUTION: A method for producing a vinyl polymer comprises: a polymerization step of obtaining a polymer solution (S1) containing a vinyl polymer (P1) having thiocarbonylthio groups by polymerizing a monomer(s) in a polymerization solvent by a reversible addition-cleavage chain transfer-type living radical polymerization method; and a reaction step of obtaining a polymer solution (S2) containing a vinyl polymer (P2) by reacting the thiocarbonylthio groups which the vinyl polymer (P1) has and an amine compound in the polymer solution (S1). In the polymerization step, a vinyl polymer is produced by a method where polymerization is carried out by using, as the polymerization solvent, a solvent (S3) containing a recovered solvent which is recovered from the polymer solution (S2) after a reaction between the vinyl polymer (P1) and the amine compound, where a content of the amine compound in the solvent (S3) is 0.025 mmol / g or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a vinyl polymer, and more particularly to a technique for producing a vinyl polymer by a reversible addition-fragmentation chain transfer living radical polymerization method. [Background technology]

[0002] Known living radical polymerization methods include reversible addition-fragmentation chain transfer polymerization (RAFT), nitroxy radical (NMP), atom transfer radical polymerization (ATRP), polymerization using organotellurium compounds (TERP), polymerization using organoantimony compounds (SBRP), polymerization using organobismuth compounds (BIRP), and iodine transfer polymerization. Among these, the RAFT, NMP, and ATRP methods are industrially used from the viewpoints of polymerization controllability and ease of implementation. In particular, the RAFT method is attracting attention as a metal-free polymerization method that can be applied to the widest range of vinyl monomers.

[0003] Vinyl polymers obtained by the RAFT method (hereinafter also referred to as "RAFT polymers") may have a problem of coloration due to thiocarbonylthio groups derived from the RAFT agent. Thus, studies have been conducted on post-treatment of the RAFT polymer to remove the thiocarbonylthio groups derived from the RAFT agent from the RAFT polymer (see, for example, Patent Documents 1 to 3).

[0004] Patent Document 1 discloses that sponge nickel is brought into contact with a RAFT polymer, and the thiocarbonylthio group of the RAFT polymer is replaced with a hydrogen atom to remove the thiocarbonylthio group of the RAFT polymer. Patent Document 2 discloses that the thiocarbonylthio group derived from the RAFT agent is removed by treating the RAFT polymer with an azo compound or a peroxide. Patent Document 3 discloses that the thiocarbonylthio group of the RAFT polymer is removed by treating the RAFT polymer with an amine compound. Of these, the method using an amine compound can be easily and quantitatively treated, and is industrially useful. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-197649 A [Patent Document 2] International Publication No. 2011 / 093401 [Patent Document 3] International Publication No. 2013 / 086585 Summary of the Invention [Problem to be solved by the invention]

[0006] In industrial production of polymers, it is common to recover the solvent used in polymerization and reuse the recovered solvent as a polymerization solvent. However, the present inventors have found that when a vinyl polymer is produced by the RAFT method, the obtained vinyl polymer is reacted with an amine compound to remove thiocarbonylthio groups, and the solvent recovered after the treatment is reused as a polymerization solvent, the molecular weight distribution of the obtained vinyl polymer becomes broad.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a vinyl polymer, which can produce a vinyl polymer having a sufficiently narrow molecular weight distribution when a vinyl polymer obtained by a RAFT method is reacted with an amine compound and the solvent recovered thereafter is reused for polymerization. [Means for solving the problem]

[0008] The present inventors have speculated that the reason why the molecular weight distribution of the vinyl polymer obtained by polymerization becomes broad when the solvent recovered after the reaction of a vinyl polymer having a thiocarbonylthio group obtained by the RAFT method with an amine compound is reused is due to the amine compound remaining unreacted in the recovered solvent. Based on this speculation, the present inventors have conducted extensive research and have completed the present invention. Specifically, the present invention provides the following means.

[0009] [1] A method for producing a vinyl polymer, comprising: a polymerization step of polymerizing monomers in a polymerization solvent by reversible addition-fragmentation chain transfer living radical polymerization to obtain a polymer solution (S1) containing a vinyl polymer (P1) having a thiocarbonylthio group; and a reaction step of reacting the thiocarbonylthio group of the vinyl polymer (P1) with at least one amine compound selected from the group consisting of primary amines and secondary amines in the polymer solution (S1) to obtain a polymer solution (S2) containing a vinyl polymer (P2), wherein in the polymerization step, polymerization is carried out using as the polymerization solvent a solvent (S3) containing a recovered solvent recovered from the polymer solution (S2) after the reaction of the vinyl polymer (P1) with the amine compound, and the content of the amine compound in the solvent (S3) is 0.025 mmol / g or less.

[0010] [2] The method for producing a vinyl polymer according to the above [1], wherein the vinyl polymer (P2) has a crosslinkable silyl group. [3] The method for producing a vinyl polymer according to [2] above, wherein the content of alcohol in the solvent (S3) is 5,000 ppm or less. [4] The method for producing a vinyl polymer according to any one of the above [1] to [3], wherein the recovered solvent is obtained by heating a solvent remaining after separating the vinyl polymer (P2) from the polymer solution (S2). [5] The method for producing a vinyl polymer according to [4] above, wherein the recovered solvent is a residue obtained by simple distillation of the solvent remaining after separating the vinyl polymer (P2) from the polymer solution (S2). [6] The method for producing a vinyl polymer according to any one of the above [1] to [5], wherein the vinyl polymer (P2) has a molecular weight distribution (Mw / Mn) of 1.9 or less. [7] The method for producing a vinyl polymer according to any one of the above [1] to [6], wherein the vinyl polymer (P1) is a block copolymer having two or more polymer blocks. Effect of the Invention

[0011] According to the present invention, even when the solvent recovered after the vinyl polymer obtained by the RAFT method is reacted with an amine compound is reused for polymerization, a vinyl polymer having a sufficiently narrow molecular weight distribution can be obtained. Therefore, according to the present invention, the productivity in the production of a vinyl polymer having a narrow molecular weight distribution can be increased. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in detail below. In this specification, "(meth)acrylic" means acrylic and / or methacrylic. "(meth)acrylate" means acrylate and / or methacrylate.

[0013] The method for producing a vinyl polymer of the present invention (hereinafter also referred to as "the present production method") produces a vinyl polymer by reversible addition-fragmentation chain transfer living radical polymerization (RAFT) and specifically includes the following polymerization and reaction steps: A polymerization step of obtaining a polymer solution (S1) containing a vinyl polymer (P1) having a thiocarbonylthio group by polymerizing a monomer in a polymerization solvent. A reaction step of reacting, in a polymer solution (S1), a thiocarbonylthio group contained in the vinyl polymer (P1) with at least one amine compound selected from the group consisting of primary amines and secondary amines to obtain a polymer solution (S2) containing a vinyl polymer (P2).

[0014] In this production method, in the polymerization step, polymerization is carried out using a solvent (S3) containing a recovered solvent recovered after the reaction of a thiocarbonylthio group of the vinyl polymer (P1) with an amine compound as a polymerization solvent. The content of the amine compound in the solvent (S3) is 0.025 mmol / g or less. The polymerization step and the reaction step in this production method will be described in detail below.

[0015] <Polymerization process> This process is a process for obtaining a polymer solution (S1) containing a vinyl polymer (P1) by the RAFT method. In the RAFT method, polymerization proceeds via a reversible chain transfer reaction in the presence of a polymerization control agent (RAFT agent) and a radical polymerization initiator.

[0016] As the RAFT agent, various known RAFT agents such as dithioester compounds, xanthate compounds, trithiocarbonate compounds, and dithiocarbamate compounds can be used. Among these, trithiocarbonate compounds can be preferably used in terms of excellent polymerization control of (meth)acrylic acid ester compounds, and specific examples thereof include S,S-dibenzyltrithiocarbonate, bis[4-(2,3-dihydroxypropoxycarbonyl)benzyl]trithiocarbonate, bis[4-(2-hydroxyethoxycarbonyl)benzyl]trithiocarbonate, and 1,4-bis(n-dodecylsulfanylthiocarbonylsulfanylmethyl)benzene. The amount of the RAFT agent used is appropriately adjusted depending on the type of monomer and RAFT agent used, etc.

[0017] In the polymerization by the RAFT method, known free radical polymerization initiators such as azo compounds, organic peroxides and persulfates can be used as the radical polymerization initiator. Among these, azo compounds are preferred because they are safe and easy to handle, and side reactions during radical polymerization are unlikely to occur. Specific examples of azo compounds include 2,2'-azobis(isobutyronitrile), 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], 2,2'-azobis(N-butyl-2-methylpropionamide), and the like. The radical polymerization initiator may be used alone or in combination of two or more kinds.

[0018] The amount of radical polymerization initiator used is not particularly limited, but from the viewpoint of obtaining a polymer with a narrower molecular weight distribution, it is preferably 0.5 mol or less, more preferably 0.4 mol or less, per 1 mol of the RAFT agent. Also, from the viewpoint of stably carrying out the polymerization reaction, the lower limit of the amount of radical polymerization initiator used is preferably 0.01 mol or more, more preferably 0.05 mol or more, per 1 mol of the RAFT agent. The amount of radical polymerization initiator used per 1 mol of the RAFT agent is preferably 0.01 to 0.5 mol, more preferably 0.05 to 0.4 mol.

[0019] In the case of the RAFT method, the polymerization reaction may be carried out in the presence of a chain transfer agent such as an alkylthiol compound having 2 to 20 carbon atoms, if necessary. In addition, a dehydrating agent such as trimethyl orthoacetate or triethyl orthoacetate may be mixed into the reaction system, if necessary. By adding a dehydrating agent to the reaction system, it is possible to suppress the progress of the crosslinking reaction during polymerization.

[0020] The monomer used for polymerization is not particularly limited, and various vinyl monomers can be used. The monomer used for polymerization preferably contains a (meth)acrylic monomer, because vinyl polymers can be produced relatively easily by the RAFT method and the monomers can be selected with a high degree of freedom.

[0021] As the (meth)acrylic monomer, at least one selected from the group consisting of (meth)acrylic acid alkyl ester compounds, (meth)acrylic acid aliphatic cyclic ester compounds, (meth)acrylic acid aromatic ester compounds, and compounds represented by the following formula (1) can be preferably used. CH2=CR 1 -C(=O)O-(R 2 O) n -R 3 …(1) (In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a linear or branched alkylene group having 2 to 6 carbon atoms; R 3 represents a hydrogen atom, 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.

[0022] (Meth)acrylic acid alkyl ester compounds 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, decyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and icosyl (meth)acrylate.

[0023] Considering the fluidity of the vinyl polymer obtained by this production method, among these, the (meth)acrylic acid alkyl ester compound can preferably be a (meth)acrylic acid alkyl ester compound in which the alkyl group (R) in the alkyl ester portion (-COOR) has 1 to 20 carbon atoms. When a (meth)acrylic acid alkyl ester compound is used as the monomer, the (meth)acrylic acid alkyl ester compound is more preferably a (meth)acrylic acid alkyl ester compound having an alkyl group with 2 to 20 carbon atoms, even more preferably a (meth)acrylic acid alkyl ester compound having an alkyl group with 2 to 18 carbon atoms, and even more preferably includes a (meth)acrylic acid alkyl ester compound having an alkyl group with 4 to 18 carbon atoms.

[0024] Aliphatic cyclic ester compounds of (meth)acrylic acid Specific examples of the aliphatic cyclic ester compounds of (meth)acrylic acid include 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.

[0025] Aromatic ester compounds of (meth)acrylic acid Specific examples of the aromatic ester compounds of (meth)acrylic acid include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, and 3-phenoxypropyl (meth)acrylate.

[0026] A compound represented by formula (1) Regarding the compound represented by the above formula (1), when n in the above formula (1) is 1, the compound represented by the above formula (1) has an oxyalkylene structure such as an oxyethylene chain, an oxypropylene chain, and an oxybutylene chain. Specific examples of the compound in which n in the above formula (1) is 1 (i.e., an (meth)acrylic acid alkoxyalkyl ester compound) 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.

[0027] When n in the above formula (1) is 2 or more, the compound represented by the above formula (1) has a polyoxyalkylene structure such as a polyoxyethylene chain, a polyoxypropylene chain, or a polyoxybutylene chain.2 may be the same or different from each other. Therefore, the compound in which n in the above formula (1) is 2 or more may have different types of polyoxyalkylene structures in one molecule, such as a block structure consisting of polyoxyethylene / polyoxypropylene.

[0028] Specific examples of the compound in which n in the above formula (1) is 2 or more include polyoxyethylene (meth)acrylate, polyoxypropylene (meth)acrylate, polyoxybutylene (meth)acrylate, polyoxyethylene-polyoxypropylene (meth)acrylate, 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.

[0029] For example, when a vinyl polymer having high fluidity is produced by the present production method, the (meth)acrylic monomer used is preferably a (meth)acrylic acid alkyl ester compound, more preferably contains a (meth)acrylic acid alkyl ester compound having an alkyl group having 2 to 18 carbon atoms, and even more preferably contains a (meth)acrylic acid alkyl ester compound having an alkyl group having 4 to 18 carbon atoms. Moreover, the (meth)acrylic monomer constituting the present polymer preferably contains at least an acrylic monomer, and more preferably contains an acrylic acid alkyl ester compound in that a polymer having excellent mechanical strength and fluidity can be obtained.

[0030] The amount of the (meth)acrylic acid alkyl ester compound used is, for example, 40 mass% or more, preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, still more preferably 80 mass% or more, and even more preferably 90 mass% or more, based on the total amount of monomers used in the polymerization.

[0031] As the monomer, a vinyl monomer (hereinafter also referred to as "other monomer") other than the above-mentioned (meth)acrylic monomer and copolymerizable therewith may be further used. Examples of the other monomer include a styrene compound, a maleimide compound, an amide group-containing vinyl compound, and a vinyl monomer having a crosslinkable functional group. The other monomer may be one or more of these.

[0032] Styrene-based compounds Specific examples of styrene-based compounds include styrene, α-methylstyrene, β-methylstyrene, vinylxylene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, pn-butylstyrene, p-isobutylstyrene, pt-butylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol, o-isopropenylphenol, o-vinylbenzoic acid, m-vinylbenzoic acid, p-vinylbenzoic acid, divinylbenzene, and vinylnaphthalene.

[0033] The amount of the styrene-based compound used is, for example, 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total amount of monomers used in the polymerization.

[0034] Maleimide compounds Specific examples of the maleimide compound include maleimide and N-substituted maleimide compounds. Examples of the N-substituted maleimide compound include N-alkyl-substituted maleimide compounds such as N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N-pentylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, and N-stearylmaleimide; N-cyclopentylmaleimide; imide, and N-cycloalkyl-substituted maleimide compounds such as N-cyclohexylmaleimide; and N-aryl-substituted maleimide compounds such as N-phenylmaleimide, N-(4-hydroxyphenyl)maleimide, N-(4-acetylphenyl)maleimide, N-(4-methoxyphenyl)maleimide, N-(4-ethoxyphenyl)maleimide, N-(4-chlorophenyl)maleimide, N-(4-bromophenyl)maleimide, and N-benzylmaleimide.

[0035] The amount of the maleimide compound used is, for example, 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total amount of monomers used in the polymerization.

[0036] Amide group-containing vinyl compounds Specific examples of the amide group-containing vinyl compound include (meth)acrylamide, (meth)acrylamide derivatives, and N-vinylamide monomers. Specific examples of the (meth)acrylamide derivatives include tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and (meth)acryloylmorpholine. Specific examples of the N-vinylamide monomers include N-vinylacetamide, N-vinylformamide, and N-vinylisobutylamide.

[0037] The amount of the amide group-containing vinyl compound used is, for example, 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, based on the total amount of monomers used in the polymerization.

[0038] · Vinyl monomers with crosslinkable functional groups Examples of the crosslinkable functional group include a crosslinkable silyl group, a silanol group, a carboxyl group, a hydroxyl group, an epoxy group, an oxazoline group, an isocyanate group, and a polymerizable unsaturated group. Of these, the crosslinkable functional group to be introduced into the vinyl polymer (P1) is preferably a crosslinkable silyl group. Since the vinyl polymer having a crosslinkable silyl group forms a crosslinked structure by dehydration condensation between the crosslinkable silyl groups, it is preferable in that the polymerization reaction during the production of the vinyl polymer (P1) and the subsequent crosslinking reaction can be efficiently carried out.

[0039] Specific examples of the crosslinkable silyl group include, for example, an alkoxysilyl group, a halogenosilyl group, etc. Among these, an alkoxysilyl group is preferred in terms of ease of controlling reactivity, and examples thereof include a trimethoxysilyl group, a methyldimethoxysilyl group, a dimethylmethoxysilyl group, a triethoxysilyl group, a methyldiethoxysilyl group, and a dimethylethoxysilyl group.

[0040] Examples of vinyl monomers having a crosslinkable functional group include crosslinkable silyl group-containing vinyl compounds, unsaturated carboxylic acids, unsaturated acid anhydrides, hydroxy group-containing vinyl compounds, epoxy group-containing vinyl compounds, primary or secondary amino group-containing vinyl compounds, oxazoline group-containing vinyl compounds, and isocyanate group-containing vinyl compounds.

[0041] Examples of the crosslinkable silyl group-containing vinyl compound 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.

[0042] Examples of the unsaturated carboxylic acid include (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamic acid, and further, monoalkyl esters of unsaturated dicarboxylic acids (monoalkyl esters of maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.), etc. Examples of the unsaturated acid anhydrides include maleic anhydride, itaconic anhydride, citraconic anhydride, etc.

[0043] Examples of the hydroxy group-containing vinyl compound include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, mono(meth)acrylic acid esters of polyalkylene glycols (e.g., polyethylene glycol, polypropylene glycol, etc.); styrene-based compounds such as o-hydroxystyrene, m-hydroxystyrene, and p-hydroxystyrene; maleimide compounds such as N-(4-hydroxyphenyl)maleimide, etc. Among the compounds represented by the above formula (1), R 3 The compound in which is a hydrogen atom is also a vinyl monomer having a crosslinkable functional group.

[0044] Examples of the epoxy group-containing vinyl compound include glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and 3,4-epoxycyclohexylmethyl (meth)acrylate.

[0045] The amount of the vinyl monomer having a crosslinkable functional group used is not particularly limited, but from the viewpoint of obtaining a vinyl polymer having excellent mechanical strength, it can be, for example, 0.01% by mass or more, and preferably 0.5% by mass or more, based on the total amount of monomers used in polymerization. The upper limit of the amount of the vinyl monomer having a crosslinkable functional group used is, for example, 40% by mass or less, and preferably 30% by mass or less, based on the total amount of monomers used in polymerization, from the viewpoint of ensuring the flexibility of the obtained vinyl polymer.

[0046] When a block copolymer having two or more polymer blocks is obtained as the vinyl polymer (P1) by this polymerization step, a polymer having a thiocarbonylthio group may be used as a raw material together with the monomer. For example, when a block copolymer having a polymer block (A) and a polymer block (B) is produced, a polymer (hereinafter also referred to as "polymer (a)") that constitutes polymer block (A) together with a monomer that constitutes polymer block (B) and has a thiocarbonylthio group can be used as a raw material. In this case, by making the polymer (a) a polymer obtained by using a monofunctional RAFT agent, an (A)-(B) diblock material consisting of polymer block (A) / polymer block (B) can be obtained. In addition, by making the polymer (a) a polymer obtained by using a bifunctional RAFT agent such as S,S-dibenzyltrithiocarbonate, an (A)-(B)-(A) triblock material consisting of polymer block (A) / polymer block (B) / polymer block (A) can be obtained. Furthermore, in the above, by using a block copolymer having two or more polymer blocks as the polymer (a), a block copolymer of a higher order can be obtained.

[0047] The polymerization reaction is carried out in a polymerization solvent known in living radical polymerization. As the polymerization solvent, various solvents can be used, such as saturated hydrocarbon compounds, aromatic compounds, ester compounds, ketone compounds, ether compounds, nitrile compounds, water, etc.

[0048] Specific examples of the polymerization solvent include saturated hydrocarbon compounds such as hexane, heptane, and cyclohexane; aromatic compounds such as benzene, toluene, xylene, and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl formate, and methyl propionate; ketone compounds such as acetone, methyl ethyl ketone, and cyclohexanone; ether compounds such as tetrahydrofuran; and nitrile compounds such as acetonitrile. Other polymerization solvents include dimethylformamide, dimethylsulfoxide, and water. As the polymerization solvent, it is preferable to use a solvent capable of dissolving the monomer. The polymerization solvent may be used alone or in combination of two or more.

[0049] In this production method, the polymerization is carried out by reusing the recovered solvent recovered after the reaction of the vinyl polymer (P1) having a thiocarbonylthio group with the amine compound. The recovered solvent will be described in detail later.

[0050] The amount of the polymerization solvent used is preferably 5 to 200 parts by mass, more preferably 10 to 100 parts by mass, relative to 100 parts by mass of the total amount of the monomers used in the polymerization. When the amount of the polymerization solvent used is 100 parts by mass or less, it is preferable in that the chain transfer to the polymerization solvent can be sufficiently suppressed and a high polymerization rate can be achieved in a short time. In addition, when the amount of the polymerization solvent used is 10 parts by mass or more, it is preferable in that the polymerization heat can be efficiently removed and an increase in the reaction temperature can be suppressed.

[0051] In the polymerization, the reaction temperature and reaction time can be appropriately set according to the type of monomer and polymerization solvent used. The reaction temperature is, for example, 40°C or more and 100°C or less, preferably 45°C or more and 90°C or less, and more preferably 50°C or more and 80°C or less. A reaction temperature of 40°C or more is preferable in that the polymerization reaction can proceed smoothly, and a reaction temperature of 100°C or less is preferable in that side reactions can be suppressed and restrictions on the initiator and polymerization solvent that can be used are relaxed. The reaction time is, for example, 1 hour or more and 48 hours or less, and preferably 2 hours or more and 24 hours or less. By such polymerization, a polymer solution (S1) containing a vinyl polymer (P1) having a thiocarbonylthio group is obtained.

[0052] <Reaction process> In this step, the polymer solution (S1) containing the vinyl polymer (P1) obtained by the polymerization step is used, and the thiocarbonylthio group of the vinyl polymer (P1) is reacted with an amine compound as a nucleophilic agent in the polymer solution (S1), thereby removing the thiocarbonylthio group of the vinyl polymer (P1) derived from the RAFT agent.

[0053] When the thiocarbonylthio group of the vinyl polymer (P1) is reacted with an amine compound, a thiol group is generated from the thiocarbonylthio group of the vinyl polymer (P1) by this reaction, and the generated thiol group reacts with the monomer remaining unreacted in the polymer solution (S1) (more specifically, a Michael addition reaction). When an acrylic acid ester compound is used as a monomer in the above polymerization step, a vinyl polymer having a terminal structure represented by the following formula (2) can be obtained as the vinyl polymer (P2). [ka] (In formula (2), R represents a residue obtained by removing an acryloyloxy group from an acrylic ester compound contained in a monomer constituting the molecular chain of a vinyl polymer.)

[0054] For example, in the above polymerization step, when S,S-dibenzyl trithiocarbonate is used as a RAFT agent to obtain a triblock copolymer as the vinyl polymer (P1), the vinyl polymer (P2) can be obtained as a diblock copolymer. In addition, in the above polymerization step, when S,S-dibenzyl trithiocarbonate is used as a RAFT agent to obtain a pentablock copolymer as the vinyl polymer (P1), the vinyl polymer (P2) can be obtained as a triblock copolymer. In addition, when 1,4-bis(alkylsulfanylthiocarbonylsulfanylmethyl)benzene is used as a RAFT agent to obtain a tetrablock copolymer as the vinyl polymer (P1), the vinyl polymer (P2) can be obtained as a tetrablock copolymer.

[0055] In this step, at least one amine compound selected from the group consisting of primary amines and secondary amines (hereinafter also referred to as "amine compound (A)") is used as the nucleophile. As the amine compound (A), known primary amines and / or secondary amines can be used, and examples thereof include primary amines such as methylamine, ethylamine, n-propylamine, n-butylamine, n-hexylamine, n-octylamine, and benzylamine; and secondary amines such as N-ethylmethylamine, N-methylpropylamine, and piperidine. The molecular weight of the amine compound (A) is preferably 150 or less, more preferably 110 or less, and even more preferably 60 or less, in terms of ease of removing unreacted nucleophile.

[0056] The amount of the amine compound (A) used is preferably 2 to 90 molar equivalents relative to the thiocarbonylthio group derived from the RAFT agent in the vinyl polymer (P1). From the viewpoint of reaction efficiency, the amount of the amine compound (A) used is preferably 2.5 molar equivalents or more relative to the thiocarbonylthio group derived from the RAFT agent, more preferably 3 molar equivalents or more, and even more preferably 3.5 molar equivalents or more. The amount of the amine compound (A) used is preferably 75 molar equivalents or less relative to the thiocarbonylthio group derived from the RAFT agent, more preferably 60 molar equivalents or less, and even more preferably 50 molar equivalents or less. By setting the amount of the amine compound (A) to 75 molar equivalents or less, it is preferable that the influence of odor due to the unreacted amine compound (A) can be reduced, and that the molecular weight distribution of the vinyl polymer obtained can be prevented from becoming broad when the recovered solvent is reused for polymerization.

[0057] The reactor used in the reaction of the thiocarbonylthio group with the amine compound (A) may be a known reactor such as a batch reactor or a tubular reactor. Of these, a batch reactor is preferred because there is less risk of clogging, which is a problem in tubular reactors. The reaction temperature is preferably 10°C or higher, more preferably 15°C or higher, and even more preferably 25°C or higher, from the viewpoint of reaction efficiency. In addition, in order to prevent side reactions (e.g., nucleophilic reactions to the polymer main chain, etc.), the reaction temperature is preferably 80°C or lower, more preferably 60°C or lower, and even more preferably 50°C or lower. The reaction pressure may usually be normal pressure, but may be increased or reduced as necessary. The reaction time is preferably 1 hour or more, more preferably 2 hours or more, and even more preferably 3 hours or more, from the viewpoint of reaction efficiency. In addition, in order to suppress side reactions such as nucleophilic reactions to the polymer main chain, the reaction time is preferably 48 hours or less, more preferably 36 hours or less, and even more preferably 24 hours or less.

[0058] According to this production method, since the RAFT method is adopted as the polymerization method, the synthesis of a block copolymer can be performed relatively easily, and a block copolymer having a narrow molecular weight distribution can be obtained. When the vinyl polymer (P2) obtained by this production method is a block copolymer having two or more polymer blocks, the number of blocks, block structure, etc. are not particularly limited.

[0059] <Solvent recovery and reuse> The above reaction step causes the reaction of the thiocarbonylthio group of the vinyl polymer (P1) with the amine compound (A) to give a polymer solution (S2) containing the vinyl polymer (P2). By subjecting the obtained polymer solution (S2) to a known solvent removal treatment, the vinyl polymer (P2) can be isolated and the solvent can be recovered. In this production method, the recovered solvent recovered after the reaction of the thiocarbonylthio group of the vinyl polymer (P1) with the amine compound (A) is reused, and the recovered solvent is used as at least a part of the polymerization solvent in a new polymerization step to be carried out thereafter.

[0060] The content of the amine compound (A) in the recovered solvent is preferably 0.025 mmol / g or less. When the content of the amine compound (A) in the recovered solvent is within the above range, the inhibition of polymer elongation due to the reaction of the thiocarbonylthio group derived from the RAFT agent in the elongated polymer with the amine compound (A) during polymerization or the reaction of the monomer with the amine compound (A) during polymerization using the recovered solvent can be suppressed. This is preferable in that the molecular weight distribution of the vinyl polymer (P2) obtained by the present production method can be sufficiently narrowed. From this viewpoint, the content of the amine compound (A) in the recovered solvent is more preferably 0.022 mmol / g or less, even more preferably 0.020 mmol / g or less, and even more preferably 0.018 mmol / g or less. In this specification, the content of the amine compound (A) in the solvent is a value measured by gas chromatography (GC). For details of the measurement method, follow the method described in the examples below.

[0061] The solvent obtained by separating the vinyl monomer (P2) from the polymer solution (S2) (hereinafter also referred to as "separated solvent") may be reused as a recovered solvent as it is as a polymerization solvent for a subsequent polymerization reaction. In addition, the separated solvent may be subjected to a treatment for reducing the content of the amine compound (A) (hereinafter also referred to as "amine reduction treatment") and then reused as a recovered solvent as a polymerization solvent for a subsequent polymerization reaction. Among these, when the polymerization solvent is reused to perform polymerization, it is preferable to reuse the separated solvent after the amine reduction treatment as a recovered solvent, in that the amount of the amine compound (A) in the reaction system can be reduced as much as possible.

[0062] The specific method of the amine reduction treatment is not particularly limited, but it is preferable to use a method of heating the separation solvent. The heating method is preferable because it can reduce the amount of the amine compound (A) in the separation solvent easily and in a short time. The separation solvent can be heated, for example, using a heating jacket or a heat exchanger provided outside the treatment vessel. The content of the amine compound (A) in the separation solvent can be adjusted by adjusting the temperature and time during heating. The temperature during the heating treatment is, for example, 30 to 65°C, preferably 35 to 60°C, depending on the type of solvent, etc. The heating treatment time is, for example, 12 to 120 hours, preferably 24 to 72 hours.

[0063] As a method for reducing the amount of the amine compound (A) by heating the separation solvent, a method for subjecting the separation solvent to simple distillation may be adopted. In the case of simple distillation, the content of the amine compound (A) in the separation solvent can be adjusted by adjusting the distillation rate or the number of times the simple distillation is performed.

[0064] Here, the recovered solvent may contain, for example, alcohol generated by hydrolysis from unreacted monomers or alcohol generated by hydrolysis from ester bonds in the copolymer. In order to reduce the influence of the presence of alcohol in the reaction system, the content of alcohol in the recovered solvent is preferably 5,000 ppm or less. If the content of alcohol in the recovered solvent is within the above range, it is preferable in that the influence of the presence of alcohol, for example, the reduction in the dehydration effect of the dehydrating agent mixed in the reaction system, can be effectively suppressed. From this viewpoint, the content of alcohol compounds in the recovered solvent is more preferably 3,000 ppm or less, even more preferably 2,000 ppm or less, even more preferably 1,500 ppm or less, and even more preferably 1,000 ppm or less. In this specification, the content of alcohol in the solvent is a value measured by gas chromatography (GC). For details of the measurement method, follow the method described in the Examples below.

[0065] In the polymerization step in which the recovered solvent is reused, a solvent containing the recovered solvent (hereinafter also referred to as "solvent (S3)") may be used as at least a part of the polymerization solvent, and the proportion of the recovered solvent contained in the polymerization solvent is not particularly limited. That is, when the polymerization is carried out by reusing the recovered solvent, the polymerization may be carried out using a part of the polymerization solvent used in the polymerization as the recovered solvent, or the polymerization may be carried out using the entire polymerization solvent as the recovered solvent. From the viewpoint of increasing the productivity of the vinyl polymer by reusing the polymerization solvent, the proportion of the recovered solvent contained in the solvent (S3) is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and even more preferably 60% by mass or more.

[0066] The content of the amine compound (A) in the solvent (S3) is 0.025 mmol / g or less. If the amount of the amine compound (A) contained in the solvent (S3) exceeds 0.025 mmol / g, the polymer elongation is easily inhibited by the reaction between the thiocarbonylthio group in the elongated polymer and the amine compound (A) or the reaction between the monomer and the amine compound (A), and the molecular weight distribution of the vinyl polymer (P2) tends to become broad. From this viewpoint, the content of the amine compound (A) in the solvent (S3) is more preferably 0.022 mmol / g or less, even more preferably 0.020 mmol / g or less, even more preferably 0.018 mmol / g or less, even more preferably 0.016 mmol / g or less, and even more preferably 0.015 mmol / g or less.

[0067] Furthermore, the alcohol content in the solvent (S3) is preferably 5,000 ppm or less, more preferably 3,000 ppm or less, even more preferably 2,000 ppm or less, even more preferably 1,500 ppm or less, even more preferably 1,000 ppm or less, and even more preferably 800 ppm or less.

[0068] According to this production method, even when a block copolymer having two or more polymer blocks is produced using a recovered solvent, a polymer having a sufficiently narrow molecular weight distribution can be obtained. For example, in the polymerization step, a (A)-(B)-(A)-(B)-(A) pentablock consisting of polymer block (A) / polymer block (B) / polymer block (A) / polymer block (B) / polymer block (A) is produced as a vinyl polymer (P1) by a RAFT method using a bifunctional RAFT agent, and then in the reaction step, a (A)-(B)-(A) triblock consisting of polymer block (A) / polymer block (B) / polymer block (A) is produced as a vinyl polymer (P2) by reacting the pentablock as the vinyl polymer (P1) with an amine compound (A). The vinyl polymer can be produced by a method including the following three steps (first to third polymerization steps) to efficiently obtain the target product.

[0069] That is, first, in the first polymerization step, a polymer block (A) is obtained using a monomer constituting the polymer block (A). Then, in the second polymerization step, a monomer constituting the polymer block (B) is polymerized to obtain an (A)-(B)-(A) triblock body consisting of polymer block (A) / polymer block (B) / polymer block (A). Furthermore, in the third polymerization step, a monomer constituting the polymer block (A) is polymerized to obtain an (A)-(B)-(A)-(B)-(A) pentablock body consisting of polymer block (A) / polymer block (B) / polymer block (A) / polymer block (B) / polymer block (A). When the vinyl polymer (P1) is produced by such a three-step process, the polymerization can be carried out using the recovered solvent as at least a part of the polymerization solvent in any of the first to third polymerization steps. At this time, the polymerization may be carried out using the recovered solvent in any one or two steps of the first to third polymerization steps, or the polymerization may be carried out using the recovered solvent in all steps.

[0070] <Molecular weight characteristics of polymers produced using recovered solvent> When a vinyl polymer (P2) is obtained by polymerization using the recovered solvent as at least a part of the polymerization solvent according to the present production method, the polystyrene-equivalent number average molecular weight (Mn) of the obtained vinyl polymer (P2) measured by gel permeation chromatography (GPC) is, for example, in the range of 2,000 to 300,000. The Mn of the vinyl polymer (P2) may be 3,000 to 200,000, 4,000 to 150,000, or 5,000 to 100,000.

[0071] In addition, according to the present production method, even when polymerization is performed using a recovered solvent, a polymer having a sufficiently narrow molecular weight distribution (Mw / Mn) can be obtained as the vinyl polymer (P2). Specifically, when polymerization is performed using at least a part of the recovered solvent as the polymerization solvent to obtain a vinyl polymer (P2) according to the present production method, the molecular weight distribution (Mw / Mn) of the vinyl polymer (P2) obtained, which is expressed by the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of polystyrene measured by GPC, is, for example, 2.0 or less, may be 1.9 or less, may be 1.8 or less, or may be 1.7 or less. According to the present production method, even when polymerization is performed by reusing the recovered solvent, a vinyl polymer having a molecular weight distribution (Mw / Mn) of less than 2.0, preferably 1.9 or less, can be obtained.

[0072] The vinyl polymer obtained by this production method can be used in a wide range of applications. Specifically, it can be used in a variety of applications, such as sealing materials, adhesives, pressure sensitive adhesives, paints, dispersants, industrial rubber, binders, coating agents, surfactants, etc. In addition, application fields include civil engineering and construction materials, packaging materials, automobile parts, home appliance and office automation equipment parts, medical equipment parts, electric wires, miscellaneous goods, etc. EXAMPLES

[0073] The present disclosure will be specifically described below based on examples, but the present disclosure is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified. The details of the analysis method for the polymers obtained in the synthesis examples, production examples, examples, and comparative examples are as follows.

[0074] <Molecular weight measurement> The resulting 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 Column: Tosoh TSKgel SuperMultiporeHZ-M x 4 Solvent: Tetrahydrofuran Temperature: 40℃ Detector: RI Flow rate: 600μL / min

[0075] <Measurement of the content of amine compounds and alcohol in recovered solvent> The obtained polymer was subjected to gas chromatography (GC) measurement under the conditions described below to obtain the n-propylamine content and methanol content in the recovered solvent. Measurement conditions Equipment: Shimadzu GC-1700 Column: InterCap for Amines 0.32mmID x 30m Inlet temperature: 180℃ Detector temperature: 250℃ Column temperature: 50℃ (5 min) → 10℃ / min → 260℃ (5 min) Detector: FID Solvent: Tetrahydrofuran

[0076] 1. Synthesis example (Synthesis Example 1: Production of Polymer a) In a 250 mL flask equipped with a stirrer, thermometer, and condenser, S,S-dibenzyl trithiocarbonate (hereinafter, also referred to as "DBTTC") (7.1 g) as a RAFT agent, 2,2'-azobis(2-methylbutyronitrile) (hereinafter, also referred to as "ABN-E") (0.47 g), n-butyl acrylate (hereinafter, also referred to as "nBA") (62 g), ethyl acrylate (hereinafter, also referred to as "EA") (4.2 g), tetradecyl acrylate (hereinafter, also referred to as "TDA") (17 g), methyldimethoxysilylpropyl methacrylate (17 g), and trimethyl orthoacetate (hereinafter, also referred to as "MOA") (5.2 g) as a dehydrating agent were charged, thoroughly degassed by nitrogen bubbling, and polymerization was initiated in a thermostatic bath at 60 ° C. After 7 hours, the reaction was stopped by cooling to room temperature (25 ° C.). The molecular weights of the obtained polymer a, as measured by GPC (gel permeation chromatography) (converted into polystyrene), were Mn 4,200, Mw 6,800, and Mw / Mn 1.62.

[0077] 2. Manufacturing Example (Production Example 1: Production of triblock copolymer b-1) In a 2L flask equipped with a stirrer, a thermometer, and a condenser, polymer a (62 g) obtained in Synthesis Example 1, nBA (706 g), EA (47 g), TDA (188 g), ABN-E (0.64 g), ethyl acetate (197 g) as a polymerization solvent, and MOA (49 g) as a dehydrating agent were charged, and the mixture was thoroughly degassed by nitrogen bubbling, and polymerization was initiated in a thermostatic bath at 60° C. After 7 hours, the mixture was cooled to room temperature to stop the reaction, and a solution containing triblock copolymer b'-1 was obtained. Methyldimethoxysilylpropyl methacrylate (9.3 g), ABN-E (0.76 g), and MOA (1.5 g) were charged into the solution containing the triblock copolymer b'-1, and the solution was thoroughly degassed by nitrogen bubbling, and polymerization was started in a thermostatic bath at 60 ° C. Copolymerization of unreacted monomers (nBA, EA, and TDA) during the production of the triblock copolymer b'-1 and newly added methyldimethoxysilylpropyl methacrylate proceeded. After 7 hours, the reaction was stopped by cooling to room temperature, and a solution containing the pentablock copolymer c-1 was obtained. The pentablock copolymer c-1 is a mixture of nBA, EA, TDA and Methyldi The copolymer has a polymer block (A) made of methoxysilylpropyl methacrylate and a polymer block (B) made of nBA, EA and TDA, and has a block structure of (A)-(B)-(A)-(B)-(A). From the reaction rate, the composition ratio (mass ratio) of the polymer block (A) and the acrylic polymer block (B) was (A) / (B) / (A) / (B) / (A)=2.4 / 43.7 / 7.8 / 43.7 / 2.4 (wt%), which means that (A) / (B) was ≒ 13 / 87 (wt%). After that, the solution containing the pentablock copolymer c-1 was thoroughly degassed by bubbling with nitrogen, and n-propylamine (3.1 g) was added, and the decomposition reaction of the trithiocarbonate group was started in a thermostatic bath at 40 ° C. After 5 hours, the reaction was stopped by cooling to room temperature, and a solution containing the triblock copolymer b-1 was obtained. This solution was vacuum dried, and the triblock copolymer b-1 and the distillate c were collected. The obtained triblock copolymer b-1 has a polymer block (A) consisting of nBA, EA, TDA, and methyldimethoxysilylpropyl methacrylate, and a polymer block (B) consisting of nBA, EA, and TDA, and is a triblock copolymer having a block structure of (A)-(B)-(A). 1 From the H-NMR measurement, it was confirmed that the peak (4.8 ppm) of hydrogen bonded to the carbon adjacent to the trithiocarbonate group observed in the pentablock copolymer c-1 disappeared in the triblock copolymer b-1, and peaks (3.3 ppm, 2.9 ppm) derived from the Michael adduct with the residual acrylate compound (terminal molecular structure represented by the above formula (2)) appeared. From this result, it can be said that the obtained triblock copolymer is a Michael adduct of the thiol formed by decomposing the trithiocarbonate group of the pentablock copolymer c-1 with n-propylamine and the residual acrylate compound contained in the block copolymer c-1. The molecular weight of the triblock copolymer b-1 was Mn 40,100, Mw 54,900, and Mw / Mn 1.37.

[0078] 3. Examples and Comparative Examples (Example 1: Production of triblock copolymer b-2) (1) Simple distillation of the distillate The distillate c (100 g) obtained in Production Example 1 was charged into a flask equipped with a stirrer, a thermometer, and a condenser, and stored at an internal temperature of 50° C. for 52 hours. Then, a simple distillation apparatus was installed, and simple distillation was performed with the external temperature kept constant at 90° C. When the distillation rate reached 32%, it was cooled to room temperature and terminated. The residue remaining in the flask was analyzed by gas chromatography, and the n-propylamine concentration was 0.0016 mmol / g and the methanol concentration was 800 ppm. The residue remaining in the flask was used as the recovered solvent d-1 for the production of the following triblock copolymer b-2.

[0079] (2) Production of triblock copolymers using recovered solvent In a 250 mL flask equipped with a stirrer, a thermometer, and a condenser, the polymer a (6.2 g) obtained in Synthesis Example 1, nBA (70 g), EA (4.7 g), TDA (19 g), ABN-E (0.06 g), and ethyl acetate (7.5 g) and recovered solvent d-1 (18 g) were charged as solvents, and the mixture was thoroughly degassed by nitrogen bubbling, and polymerization was started in a thermostatic bath at 60 ° C. After 7 hours, the reaction was stopped by cooling to room temperature, and a solution containing triblock copolymer b'-2 was obtained. The n-propylamine concentration in the polymerization solvent (a mixture of 7.5 g of ethyl acetate and 18 g of recovered solvent d-1) was 0.0011 mmol / g, and the methanol concentration was 565 ppm. Next, methyldimethoxysilylpropyl methacrylate (0.93 g), ABN-E (0.076 g), and MOA (0.15 g) were charged into the solution containing the triblock copolymer b'-2, and the solution was thoroughly degassed by nitrogen bubbling, and polymerization was started in a thermostatic bath at 60 ° C. Copolymerization of unreacted monomers (nBA, EA, and TDA) during the production of the triblock copolymer b'-2 and newly added methyldimethoxysilylpropyl methacrylate proceeded. After 7 hours, the reaction was stopped by cooling to room temperature, and a solution containing the pentablock copolymer c-2 was obtained. After that, the solution containing the pentablock copolymer c-2 was thoroughly degassed by nitrogen bubbling, and n-propylamine (0.31 g) was charged, and the decomposition reaction of the trithiocarbonate group was started in a thermostatic bath at 40 ° C. After 5 hours, the reaction was stopped by cooling to room temperature, and a solution containing the triblock copolymer b-2 was obtained. This solution was vacuum dried to recover the triblock copolymer b-2. The obtained triblock copolymer b-2 has a polymer block (A) consisting of nBA, EA, TDA, and methyldimethoxysilylpropyl methacrylate, and a polymer block (B) consisting of nBA, EA, and TDA, and is a triblock copolymer having a block structure of (A)-(B)-(A). The molecular weight of the triblock copolymer b-2 was Mn 41,000, Mw 55,600, and Mw / Mn 1.36.

[0080] (Example 2: Production of triblock copolymer b-3) (1) Heating the distillate The distillate c (100 g) obtained in Production Example 1 was charged into a flask equipped with a stirrer, a thermometer, and a condenser, and stored at an internal temperature of 50° C. for 4 days. The solvent remaining in the flask was analyzed by gas chromatography, and the n-propylamine concentration was 0.014 mmol / g and the methanol concentration was 4,900 ppm. The solvent remaining in the flask was used as recovered solvent d-2 for the production of triblock copolymer b-3.

[0081] (2) Production of triblock copolymers using recovered solvent In a 250 mL flask equipped with a stirrer, a thermometer, and a condenser, polymer a (6.2 g) obtained in Synthesis Example 1, nBA (70 g), EA (4.7 g), TDA (19 g), ABN-E (0.06 g), MOA (0.3 g) as a dehydrating agent, and recovered solvent d-2 (25 g) as a solvent were charged, thoroughly degassed by nitrogen bubbling, and polymerization was initiated in a thermostatic bath at 60° C. After 7 hours, the reaction was stopped by cooling to room temperature to obtain a solution containing triblock copolymer b'-3. Methyldimethoxysilylpropyl methacrylate (0.93 g), ABN-E (0.076 g), and MOA (0.15 g) as a dehydrating agent were charged into the solution containing the triblock copolymer b'-3, and the solution was thoroughly degassed by nitrogen bubbling, and polymerization was started in a thermostatic bath at 60 ° C. Copolymerization of unreacted monomers (nBA, EA, and TDA) during the production of the triblock copolymer b'-3 and newly added methyldimethoxysilylpropyl methacrylate proceeded. After 7 hours, the solution was cooled to room temperature to stop the reaction, and a solution containing the pentablock copolymer c-3 was obtained. After that, the solution containing the pentablock copolymer c-3 was thoroughly degassed by nitrogen bubbling, and n-propylamine (0.31 g) was added, and the decomposition reaction of the trithiocarbonate group was started in a thermostatic bath at 40 ° C. After 5 hours, the reaction was stopped by cooling to room temperature, and a solution containing the triblock copolymer b-3 was obtained. This solution was vacuum dried, and the triblock copolymer b-3 was recovered. The obtained triblock copolymer b-3 has a polymer block (A) consisting of nBA, EA, TDA, and methyldimethoxysilylpropyl methacrylate, and a polymer block (B) consisting of nBA, EA, and TDA, and is a triblock copolymer having a block structure of (A)-(B)-(A). The molecular weight of the obtained triblock copolymer b-3 was Mn 41,600, Mw 67,500, and Mw / Mn 1.62.

[0082] (Comparative Example 1: Production of triblock copolymer b-4) (1) Heating the distillate The distillate c (100 g) obtained in Production Example 1 was charged into a flask equipped with a stirrer, a thermometer, and a condenser, and stored at 50° C. for 52 hours. Analysis by gas chromatography showed that the n-propylamine concentration was 0.027 mmol / g and the methanol concentration was 5,400 ppm. The solvent remaining in the flask was used as recovered solvent d-3 for the production of a triblock copolymer.

[0083] (2) Production of triblock copolymers using recovered solvent In a 250 mL flask equipped with a stirrer, a thermometer, and a condenser, polymer a (6.2 g) obtained in Synthesis Example 1, nBA (70 g), EA (4.7 g), TDA (19 g), ABN-E (0.06 g), MOA (0.3 g) as a dehydrating agent, and recovered solvent d-3 (25 g) as a solvent were charged, and the mixture was thoroughly degassed by nitrogen bubbling, and polymerization was initiated in a thermostatic bath at 60° C. After 7 hours, the mixture was cooled to room temperature to stop the reaction, and a solution containing triblock copolymer b'-4 was obtained. Methyldimethoxysilylpropyl methacrylate (0.93 g), ABN-E (0.076 g), and MOA (0.15 g) as a dehydrating agent were charged into the solution containing the triblock copolymer b'-4, and the solution was thoroughly degassed by nitrogen bubbling, and polymerization was started in a thermostatic bath at 60 ° C. Copolymerization of unreacted monomers (nBA, EA, and TDA) during the production of the triblock copolymer b'-4 and newly added methyldimethoxysilylpropyl methacrylate proceeded. After 7 hours, the solution was cooled to room temperature to stop the reaction, and a solution containing the pentablock copolymer c-4 was obtained. After that, the solution containing the pentablock copolymer c-4 was thoroughly degassed by bubbling with nitrogen, and n-propylamine (0.31 g) was added, and the decomposition reaction of the trithiocarbonate group was started in a thermostatic bath at 40 ° C. After 5 hours, the reaction was stopped by cooling to room temperature, and a solution containing the triblock copolymer b-4 was obtained. This solution was vacuum dried, and the triblock copolymer b-4 was recovered. The obtained triblock copolymer b-4 has a polymer block (A) consisting of nBA, EA, TDA, and methyldimethoxysilylpropyl methacrylate, and a polymer block (B) consisting of nBA, EA, and TDA, and is a triblock copolymer having a block structure of (A)-(B)-(A). The molecular weight of the triblock copolymer b-4 was Mn 42,500, Mw 88,900, and Mw / Mn 2.09.

[0084] 4.Results In the production of triblock copolymers by the RAFT method in Examples 1 and 2, solvents with sufficiently low n-propylamine concentrations of 0.0011 mmol / g and 0.014 mmol / g were used as polymerization solvents in the polymerization process in which the recovered solvent was reused, thereby enabling the production of triblock copolymers with sufficiently narrow molecular weight distributions of 1.36 and 1.62, respectively.

[0085] On the other hand, in Comparative Example 1, a recovered solvent having an n-propylamine concentration of 0.027 mmol / g was used as the polymerization solvent, and the resulting triblock copolymer b-4 had a broader molecular weight distribution of 2.09 than the triblock copolymer b-1 obtained in Production Example 1. In addition, the results of measuring the molecular weight distribution by GPC showed that the triblock copolymer b-4 obtained in Comparative Example 1 contained two types of polymers: a polymer having a lower molecular weight than the triblock copolymer b-1 obtained in Production Example 1, and a polymer having a higher molecular weight than the triblock copolymer b-1.

[0086] In Comparative Example 1, a polymer having a lower molecular weight than the triblock copolymer b-1 obtained in Production Example 1 was obtained. This is believed to be because the primary amine (n-propylamine) in the recovered solvent reacted with the trithiocarbonate group in the polymer a, and polymer elongation did not occur sufficiently in some polymer chains. On the other hand, the trithiocarbonate group that remained without reacting with the primary amine in the recovered solvent reacted with the monomer, which caused the polymer chain to elongate. In Comparative Example 1, the ratio of the monomer to the RAFT agent was higher than the designed ratio, and this is believed to have resulted in a polymer having a higher molecular weight than the triblock copolymer b-1. Therefore, it is believed that the molecular weight distribution was broadened due to the combination of a low molecular weight polymer and a high molecular weight polymer.

Claims

1. a polymerization step of polymerizing a monomer in a polymerization solvent by a reversible addition-fragmentation chain transfer living radical polymerization method to obtain a polymer solution (S1) containing a vinyl polymer (P1) having a thiocarbonylthio group; a reaction step of reacting, in the polymer solution (S1), a thiocarbonylthio group contained in the vinyl polymer (P1) with at least one amine compound selected from the group consisting of primary amines and secondary amines to obtain a polymer solution (S2) containing a vinyl polymer (P2); Including, In the polymerization step, polymerization is carried out using, as the polymerization solvent, a solvent (S3) containing a recovered solvent recovered from the polymer solution (S2) after the reaction of the vinyl polymer (P1) with the amine compound, The method for producing a vinyl polymer, wherein the content of the amine compound in the solvent (S3) is 0.025 mmol / g or less.

2. The method for producing a vinyl polymer according to claim 1, wherein the vinyl polymer (P2) has a crosslinkable silyl group.

3. 3. The method for producing a vinyl polymer according to claim 1, wherein the solvent (S3) has an alcohol content of 5,000 ppm or less.

4. The method for producing a vinyl polymer according to any one of claims 1 to 3, wherein the recovered solvent is obtained by heating a solvent remaining after separating the vinyl polymer (P2) from the polymer solution (S2).

5. The method for producing a vinyl polymer according to claim 4, wherein the recovered solvent is a residue obtained by simple distillation of the solvent remaining after separating the vinyl polymer (P2) from the polymer solution (S2).

6. The method for producing a vinyl polymer according to any one of claims 1 to 5, wherein the molecular weight distribution (Mw / Mn) of the vinyl polymer (P2) is 1.9 or less.

7. The method for producing a vinyl polymer according to any one of claims 1 to 6, wherein the vinyl polymer (P1) is a block copolymer having two or more polymer blocks.

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