Method for producing polymer

Abstract

To provide a method for producing a polymer capable of obtaining a polymer having a precisely controlled molecular weight by mild temperature conditions.SOLUTION: There is produced a polymer by polymerizing a monomer comprising at least one selected from the group consisting of compounds represented by formulas (1) to (4) in a solvent in the presence of an anionic polymerization initiator and a compound represented by the formula (5), wherein the solvent is at least one specific solvent selected from the group consisting of an ether compound, an ester compound, a ketone compound, a nitrile compound and an amide compound, which has no anionic polymerizability. Wherein, R1 represents a hydrocarbyl group having 1 to 20 carbon atoms, which may be substituted with a heteroelement-containing group and Ar1 represents a monovalent group bonded to an oxygen atom by a benzene ring, in which a secondary carbon atom or a tertiary carbon atom is respectively bonded to the carbon atoms at the 2- and 6-positions of the benzene ring and a hydrogen atom, a chlorine atom, a hydrocarbyl group having 1 to 6 carbon atoms or the like are bonded to the carbon atom at the 4-position.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polymer, and more particularly to a technique for polymerizing an acrylic monomer in a solvent. [Background technology]

[0002] Living polymerization is a polymerization reaction consisting of an initiation reaction and a propagation reaction, without side reactions such as chain transfer reactions or termination reactions. By using living polymerization, it is possible to control the length of the polymer chain and also to produce block copolymers or polymers with introduced terminal groups (see, for example, Non-Patent Document 1). This makes it possible to impart high functionality to polymers or products manufactured using such polymers, and to freely design polymers with unique terminal structures to impart new functions. In fact, living polymerization is also useful industrially as a method for producing functional polymers (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-152983 [Patent Document 2] Japanese Patent Application Publication No. 2019-043883 [Patent Document 3] Japanese Patent Publication No. 2020-111624 [Non-patent literature]

[0004] [Non-Patent Document 1] D.Baskaran,Prog. Polym.Sci.28,2003,521-581 Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in Non-Patent Document 1, for example, anionic polymerization of acrylic monomers, such as (meth)acrylates, is known to behave as living polymerization when the anionic polymerization initiator, solvent, and temperature are appropriately selected. However, various restrictions on the reaction conditions for anionic polymerization of acrylic monomers exist, and these restrictions pose a technical barrier to the industrialization of anionic polymerization of acrylic monomers. Furthermore, constructing new polymerization systems is considered effective as a means of developing novel polymeric materials and increasing productivity. For example, regarding temperature, a low temperature of −15°C or below is a typical polymerization condition for achieving living polymerization in order to suppress side reactions. However, from an industrial perspective, a technology that enables polymerization under as mild a temperature condition as possible is desired.

[0006] The present invention has been made in view of the above-mentioned problems, and a main object of the present invention is to provide a method for producing a polymer by which a polymer having a precisely controlled molecular weight can be obtained under mild temperature conditions. [Means for solving the problem]

[0007] In order to solve the above problems, in one embodiment of the present invention, there is provided a compound represented by the following formulas (1) to (4): [ka] (In formulas (1) to (4), R 1 represents a hydrocarbyl group having 1 to 20 carbon atoms, which may be substituted with a heteroatom-containing group having at least one element selected from the group consisting of nitrogen, oxygen, sulfur, and halogen. 2 , R 3 and R 6 R each independently represents a hydrogen atom, a halogen atom, or a substituent having one or more carbon atoms. 4 and R 5 are each independently a hydrogen atom or a substituent having one or more carbon atoms, or R 4 and R 5 are combined together, R 4 and R 5represents a ring structure formed together with the nitrogen atom to which R is attached. 7 represents a divalent linking group. In a solvent, a monomer containing at least one selected from the group consisting of compounds represented by the following formula (5): [ka] (In formula (5), Ar 1 represents a monovalent group bonded to the oxygen atom in the formula via a benzene ring, in which a secondary carbon or a tertiary carbon is bonded to the carbon at the 2nd and 6th positions of the benzene ring, respectively, and a hydrogen atom, a chlorine atom, a fluorine atom, a hydrocarbyl group having 1 to 6 carbon atoms, or a hydrocarbyloxy group having 1 to 6 carbon atoms is bonded to the carbon at the 4th position. 10 represents an alkyl group having 2 to 10 carbon atoms. wherein the solvent contains a specific solvent that is at least one selected from the group consisting of ether compounds, ester compounds, ketone compounds, nitrile compounds, and amide compounds and does not have anionic polymerizability. [Effects of the Invention]

[0008] According to the present invention, a polymer with a precisely controlled molecular weight can be obtained under mild temperature conditions. DETAILED DESCRIPTION OF THE INVENTION

[0009] Matters related to the embodiments of the present disclosure will be described in detail below. In this specification, a numerical range indicated using "to" means that the numerical values ​​before and after "to" are included as the lower and upper limits. Unless otherwise specified, each component may be used singly or in combination of two or more. In this specification, "(meth)acrylic" is a term that encompasses "acrylic" and "methacrylic." Molecular weight distribution refers to a value (Mn / Mw) expressed as the ratio of number average molecular weight (Mn) to weight average molecular weight (Mw).

[0010] <Polymer manufacturing method> The method for producing a polymer according to the present disclosure (hereinafter also referred to as "the present production method") includes a step of polymerizing an acrylic monomer as a monomer in a solvent in the presence of an anionic polymerization initiator and an organoaluminum compound. In the polymerization system according to the present disclosure, it is believed that the organoaluminum compound used together with the anionic polymerization initiator functions as a Lewis acid catalyst, thereby causing the polymerization reaction (specifically, anionic polymerization reaction) to proceed.

[0011] In the anionic polymerization of acrylic monomers, the initiation reaction must generate the corresponding enolate species of the acrylic monomer. Therefore, initiators and initiator systems typically use highly nucleophilic reactants, such as alkyllithiums or Grignard reagents. At the same time, it is necessary to suppress side reactions in which the initiator and initiator system attacks the functional groups of the acrylic monomer, specifically the carbonyl and cyano groups. Therefore, bulky initiators, such as tert-butyllithium, are typically used. Furthermore, to achieve homogeneous polymerization, the solvent used must be selected taking into account the solubility of the monomer and polymer. Furthermore, the solvent and temperature affect the polymerization rate. In particular, the anionic polymerization of acrylic monomers involves side reactions in which the initiator and initiator system or propagating species add to the carbonyl and cyano groups of the acrylic monomer. Suppressing these side reactions is a key requirement for achieving living polymerization. Furthermore, since side reactions are more likely to occur at higher temperatures, anionic polymerization is usually carried out at low temperatures of -15°C or lower.

[0012] The above-mentioned constraints on reaction conditions are a technical barrier to the industrialization of anionic polymerization of acrylic monomers. Furthermore, constructing new polymerization systems is considered effective as a means to develop novel polymeric materials and increase productivity. For example, regarding temperature, as mentioned above, a low temperature of −15°C or lower is a typical polymerization condition for achieving living polymerization. However, from an industrial perspective, a technology that enables polymerization under as mild a temperature condition as possible is required. In this regard, the present production method allows for the production of polymers with precisely controlled molecular weights under mild temperature conditions. The details of this production method are described below.

[0013] <Monomer> The monomer used in the present production method includes at least one acrylic monomer selected from the group consisting of compounds represented by the following formulas (1) to (4). [ka] (In formulas (1) to (4), R 1 represents a hydrocarbyl group having 1 to 20 carbon atoms, which may be substituted with a heteroatom-containing group having at least one element selected from the group consisting of nitrogen, oxygen, sulfur, and halogen. 2 , R 3 and R 6 R each independently represents a hydrogen atom, a halogen atom, or a substituent having one or more carbon atoms. 4 and R 5 are each independently a hydrogen atom or a substituent having one or more carbon atoms, or R 4 and R 5 are combined together, R 4 and R 5 represents a ring structure formed together with the nitrogen atom to which R is attached. 7 represents a divalent linking group.

[0014] In the above formulas (1) to (4), R 2 or R 3Examples of the substituent having 1 or more carbon atoms represented by R include a hydrocarbyl group having 1 to 6 carbon atoms and a halogenated hydrocarbyl group having 1 to 6 carbon atoms. 2 or R 3 From the viewpoint of polymerizability, is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0015] R 1 Examples of the hydrocarbyl group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent saturated or unsaturated chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. In this specification, the chain hydrocarbon group includes a straight chain and a branched chain. The alicyclic hydrocarbon group is not limited to being composed solely of an alicyclic hydrocarbon structure, and may have a chain structure as part of it. Furthermore, the aromatic hydrocarbon group is not limited to being composed solely of an aromatic ring structure, and may have a chain structure or an alicyclic hydrocarbon structure as part of it.

[0016] R 1 may be a group in which any hydrogen atom of a hydrocarbyl group having 1 to 20 carbon atoms has been substituted with a hetero element-containing group (hereinafter simply referred to as a "hetero element-containing group") having at least one element selected from the group consisting of nitrogen, oxygen, sulfur, and halogen. Examples of the hetero element-containing group include an oxetanyl group, an oxiranyl group, an amino group, a thiol group, a hydroxy group, a halo group (such as a fluoro group, a chloro group, a bromo group, or an iodo group), and a cyano group.

[0017] R 4 or R 5 Examples of the substituent having 1 or more carbon atoms represented by the formula (R) include a monovalent substituted or unsubstituted hydrocarbyl group having 1 to 20 carbon atoms. 4 or R 5 When has a substituent, examples of the substituent include the hetero element-containing groups described above. R 4 and R 5 are combined together, R 4 and R 5Examples of the ring structure formed together with the nitrogen atom to which the ring is bonded include a piperidine ring structure and a morpholine ring structure.

[0018] R 6 Examples of the substituent having 1 or more carbon atoms represented by R include a hydrocarbyl group having 1 to 6 carbon atoms and a halogenated hydrocarbyl group having 1 to 6 carbon atoms. 6 From the viewpoint of polymerizability, is preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms.

[0019] R 7 The divalent linking group represented by the following formula is preferably a linear or branched alkanediyl group having 1 to 6 carbon atoms, more preferably a linear or branched alkanediyl group having 1 to 4 carbon atoms.

[0020] Specific examples of the compound represented by the above formula (1) ((meth)acrylic acid ester compound) include (meth)acrylic acid alkyl esters, (meth)acrylic acid alkenyl esters, alkylene glycol (meth)acrylic acid esters, (meth)acrylic acid esters having an alicyclic structure, and (meth)acrylic acid esters having an aromatic ring structure, and one or more hydrogen atoms of these compounds may be substituted with a hetero element-containing group.

[0021] Further specific examples of the compound represented by the above formula (1) include alkyl (meth)acrylates or alkenyl (meth)acrylates which may be substituted with a heteroatom-containing group, such as methyl (meth)acrylate, ethyl (meth)acrylate, vinyl (meth)acrylate, allyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, and (meth)acrylate. Examples of the copolymer include n-stearyl (meth)acrylate, glycidyl (meth)acrylate, hydroxyethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 2-bromoethyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, perfluoroethyl (meth)acrylate, cyanomethyl (meth)acrylate, 1-cyanoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, 2-cyanopropyl (meth)acrylate, 3-cyanopropyl (meth)acrylate, 4-cyanobutyl (meth)acrylate, 6-cyanohexyl (meth)acrylate, and 2-ethyl-6-cyanohexyl (meth)acrylate.

[0022] Specific examples of alkylene glycol (meth)acrylic acid esters which may be substituted with a heteroatom-containing group include polyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, and polyethylene glycol-polypropylene glycol (meth)acrylate.

[0023] Examples of the (meth)acrylic acid ester having an alicyclic structure which may be substituted with a heteroatom-containing group include cyclohexyl (meth)acrylate, 2-methylcyclohexyl (meth)acrylate, tricyclo[5.2.1.0](meth)acrylate, and the like.2,6 ] decan-8-yl, (meth)acrylic acid tricyclo[5.2.1.0 2,5 ] decan-8-yloxyethyl, isobornyl (meth)acrylate, adamantyl (meth)acrylate, (perfluorocyclohexyl)methyl (meth)acrylate, and (3,4-epoxycyclohexyl)methyl (meth)acrylate.

[0024] Examples of the (meth)acrylic acid ester having an aromatic ring structure which may be substituted with a heteroatom-containing group include phenyl (meth)acrylate, benzyl (meth)acrylate, and pentafluorophenyl (meth)acrylate.

[0025] Examples of the compound represented by the above formula (2) (amide group-containing vinyl compound) include tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, (meth)acryloylmorpholine, and N-vinylacetamide.

[0026] Examples of the compound represented by the above formula (3) (cyano group-containing vinyl compound) include acrylonitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-fluoroacrylonitrile, and α-chloroacrylonitrile.

[0027] Specific examples of the compound represented by the above formula (4) (α-methylene lactone compound) include α-methylene-γ-butyrolactone and α-methylene-δ-valerolactone.

[0028] The monomer used in this production method preferably contains a compound represented by the above formula (1), and more preferably contains a (meth)acrylic acid alkyl ester, in terms of being able to increase the reaction rate of the monomer and being able to obtain a polymer with a narrower molecular weight distribution (Mw / Mn). The (meth)acrylic acid alkyl ester is preferably a compound represented by the above formula (1), and more preferably contains a (meth)acrylic acid alkyl ester. 1is preferably a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and more preferably a substituted or unsubstituted alkyl group having 1 to 16 carbon atoms. 1 When has a substituent, examples of the substituent include the functional groups exemplified as the hetero element-containing group.

[0029] Of the monomers used in this production method, the amount of the compound represented by the above formula (1) (i.e., the (meth)acrylic acid ester compound) used is preferably 50 mol % or more, more preferably 60 mol % or more, even more preferably 70 mol % or more, and even more preferably 80 mol % or more, from the viewpoint of improving controllability of the molecular weight and molecular weight distribution.

[0030] <Anionic polymerization initiator> As the anionic polymerization initiator, from the viewpoint of sufficiently proceeding with the polymerization reaction of the monomer, a salt of an anion of a conjugate acid having an acidity constant (pKa) of 10 or less in water at 25°C and an ammonium or phosphonium cation can be preferably used.

[0031] Specific examples of the anion contained in the anionic polymerization initiator include a carboxylate ion, an azide ion, a thiol, a phenol, a 2,4-dinitrophenol ion, etc. From the viewpoint of easy availability of the anionic polymerization initiator, the anion contained in the anionic polymerization initiator is preferably a carboxylate ion or an azide ion, and more preferably a carboxylate ion.

[0032] When the anionic polymerization initiator is a salt of a carboxylate ion and an ammonium cation (hereinafter also referred to as a "carboxylate compound"), the carboxylate compound may be any compound that can function as a polymerization initiator by generating a carboxylate ion in the polymerization system. Specific examples of the carboxylate compound include "R 4 COO - N(R 5 )4 + " (wherein R 4 and R 5are each independently a hydrocarbyl group having 1 to 20 carbon atoms. 5 are the same or different.

[0033] Carboxylic acid (R) gives ammonium carboxylate 4 Examples of the carboxylic acid (R —COOH) include aliphatic carboxylic acids and aromatic carboxylic acids. Specific examples of these include saturated fatty acids such as acetic acid, propionic acid, butyric acid, isobutyric acid, pivalic acid, valeric acid, caproic acid, enanthic acid, caprylic acid, lauric acid, myristic acid, and stearic acid as aliphatic carboxylic acids; and unsaturated fatty acids such as oleic acid, linoleic acid, arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid as aliphatic carboxylic acids. Examples of aromatic carboxylic acids include benzoic acid and phthalic acid. Of these, saturated fatty acids or aromatic carboxylic acids are preferred as the carboxylic acid that gives the ammonium carboxylate. 4a -COOH" (where R 4a is a linear or branched alkyl group having 1 to 12 carbon atoms or a phenyl group.) is more preferred.

[0034] Ammonium (N(R 5 )4 + ) about R 5 is preferably a linear or branched alkyl group having 1 to 12 carbon atoms or a phenyl group. Specific examples of ammonium include tetramethylammonium, tetraethylammonium, diethyldimethylammonium, tetrapropylammonium, tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, tetraheptylammonium, tetraoctylammonium, tetradecylammonium, and tetradodecylammonium.

[0035] Specific examples of the carboxylate compound include compounds formed by any combination of the carboxy anions derived from the carboxylic acids listed above and ammonium, including the compounds represented by the following formulas (6-1) to (6-6). [ka]

[0036] During polymerization, the amount of anionic polymerization initiator used can be appropriately set depending on the desired molecular weight of the polymer obtained by this production method. From the viewpoint of sufficiently progressing the polymerization reaction, the amount of anionic polymerization initiator used is preferably 0.001 molar parts or more, more preferably 0.002 molar parts or more, and even more preferably 0.003 molar parts or more, relative to a total of 100 molar parts of the monomers used in polymerization. Furthermore, from the viewpoint of avoiding excessive addition, the amount of anionic polymerization initiator used is preferably 10 molar parts or less, more preferably 5 molar parts or less, and even more preferably 3 molar parts or less, relative to a total of 100 molar parts of the monomers used in polymerization.

[0037] <Organoaluminum compounds> In this production method, polymerization of monomers is carried out in the presence of an organoaluminum compound represented by the following formula (5) (hereinafter also simply referred to as "organoaluminum compound"). [ka] (In formula (5), Ar 1 represents a monovalent group bonded to the oxygen atom in the formula via a benzene ring, in which a secondary carbon or a tertiary carbon is bonded to the carbon at the 2nd and 6th positions of the benzene ring, respectively, and a hydrogen atom, a chlorine atom, a fluorine atom, a hydrocarbyl group having 1 to 6 carbon atoms, or a hydrocarbyloxy group having 1 to 6 carbon atoms is bonded to the carbon at the 4th position. 10 represents an alkyl group having 2 to 10 carbon atoms.

[0038] In the above formula (5), Ar 1 The carbon atoms at the 2nd and 6th positions of the benzene ring of the monovalent group represented by the formula (1) are bonded to a secondary carbon or a tertiary carbon, respectively. 1A group having a secondary carbon or a tertiary carbon (hereinafter also referred to as a "specific carbon-containing group") is bonded to the 2-position and the 6-position of the benzene ring of the monovalent group represented by the formula (5). The specific carbon-containing groups in the formula (5) may be the same or different. For example, the specific carbon-containing group bonded to the 2-position of the benzene ring may be a group having a secondary carbon, and the specific carbon-containing group bonded to the 6-position may be a group having a tertiary carbon.

[0039] The specific carbon-containing group is preferably a hydrocarbyl group (more specifically, a hydrocarbyl group having a secondary or tertiary carbon and bonded to a benzene ring via the secondary or tertiary carbon), and specific examples thereof include a monovalent chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The specific carbon-containing group is preferably a monovalent chain hydrocarbon group, and more preferably a secondary alkyl group or a tertiary alkyl group. Specific preferred examples of the specific carbon-containing group include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group.

[0040] Here, "secondary carbon" refers to a carbon that is bonded to two hydrocarbon groups, excluding the bond to the benzene ring. "Tertiary carbon" refers to a carbon that is bonded to three hydrocarbon groups, excluding the bond to the benzene ring.

[0041] Ar 1 The carbon atom at the 4-position of the benzene ring of the monovalent group represented by the following formula is bonded to a hydrogen atom, a chlorine atom, a fluorine atom, a hydrocarbyl group having 1 to 6 carbon atoms, or a hydrocarbyloxy group having 1 to 6 carbon atoms. Examples of the hydrocarbyl group having 1 to 6 carbon atoms and the hydrocarbyl group in the hydrocarbyloxy group having 1 to 6 carbon atoms include a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Of these, the hydrocarbyl group is preferably a chain hydrocarbon group, and more preferably an alkyl group.

[0042] R 10 The alkyl group having 2 to 10 carbon atoms represented by the formula (R) may be linear or branched. 10Specific examples of the alkyl group include an ethyl group, an n-propyl group, an isopropyl group, an -butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 1,1-dimethylbutyl group, an n-pentyl group, an isopentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group.

[0043] A preferred example of the organoaluminum compound is a compound represented by the following formula (5A). [ka] (In formula (5A), R 11 and R 12 R each independently represent a hydrocarbyl group having a secondary or tertiary carbon and bonded to the benzene ring at the secondary or tertiary carbon. 13 represents a hydrogen atom, a chlorine atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 10 represents an alkyl group having 2 to 10 carbon atoms.

[0044] R 11 and R 12 is preferably a hydrocarbyl group having a tertiary carbon and bonded to the benzene ring at the tertiary carbon, and more preferably an alkyl group having a tertiary carbon and bonded to the benzene ring at the tertiary carbon.

[0045] Specific examples of the organoaluminum compound include compounds represented by the following formulas (5-1) to (5-8), in which "Et" represents an ethyl group, "iBu" represents an isobutyl group, and "Oc" represents an n-octyl group. [ka]

[0046] In the polymerization, the amount of the organoaluminum compound used is desirably 1 part by mol or more, preferably 2 to 10 parts by mol, and more preferably 3 to 5 parts by mol, relative to the anionic polymerization initiator.

[0047] <Polymerization solvent> In this production method, a solution polymerization method is used as the polymerization method, in which the monomers are polymerized in a solvent containing at least one solvent selected from the group consisting of ether compounds, ester compounds, ketone compounds, nitrile compounds, and amide compounds, which is not anionically polymerizable (hereinafter also referred to as a "specific solvent").

[0048] The specific solvent is preferably an organic solvent that is a compound that does not have anionic polymerization properties and can dissolve or disperse each component contained in the polymerization system without reacting with each component. Specific examples of the specific solvent include ether compounds such as chain ethers such as diethyl ether, diisopropyl ether, dibutyl ether, tert-butyl methyl ether, diethoxymethane, dimethoxyethane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol dimethyl ether (diglyme), diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol butyl methyl ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ether (triglyme), triethylene glycol butyl methyl ether, and tetraethylene glycol dimethyl ether (tetraglyme); Cyclic ethers such as tetrahydrofuran, tetrahydropyran, 4-methyltetrahydropyran, 2-methyltetrahydrofuran, methoxycyclopentane, 1,3-dioxolane, 1,4-dioxane, cyclopentyl methyl ether, and furan; and the like.

[0049] Specific examples of the ester compound include chain esters such as ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, methoxybutyl acetate, amyl acetate, methyl lactate, ethyl lactate, butyl lactate, methyl isobutyrate, ethyl isobutyrate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and methyl-3-methoxypropionate; and cyclic esters such as γ-butyrolactone.

[0050] Specific examples of the ketone compound include chain ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, benzophenone, and acetophenone; Cyclic ketones such as cyclobutanone, cyclopentanone, cyclohexanone, and isophorone; and the like.

[0051] Specific examples of the nitrile compound include chain nitriles such as acetonitrile, propionitrile, butanenitrile, isobutyronitrile, and valeronitrile; Cyclic nitriles such as cyclopentanecarbonitrile and cyclohexanecarbonitrile; and the like.

[0052] Specific examples of the amide compound include formamide, acetamide, benzamide, N,N-diethylformamide, N,N-diethylacetamide, and acetanilide.

[0053] The specific solvent preferably contains at least one compound selected from the group consisting of ether compounds and ester compounds, which does not have anionic polymerizability. Of these, at least one selected from the group consisting of cyclic ethers having 3 to 6 carbon atoms, chain ethers having 3 to 12 carbon atoms, and chain esters having 3 to 8 carbon atoms can be preferably used as the specific solvent. Specifically, at least one selected from the group consisting of compounds represented by the following formula (4-1), compounds represented by the following formula (4-2), and compounds represented by the following formula (4-3) can be mentioned. [ka] (In formula (4-1), m1 is 2 or 3. m2 is 0 or 1. In formula (4-2), R 9 is an alkyl group having 1 to 3 carbon atoms. 10 is an ethylene group, a 1,2-propanediyl group, or a 1,3-propanediyl group. 11 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. m3 is an integer of 1 to 4. However, R 9 The number of carbon atoms and R 10 m3 times the number of carbon atoms and R 11 The total number of carbon atoms in the R is 12 or less. When m3 is 2 or more, multiple R 10 are the same or different. In formula (4-3), R 12 and R 13 are each independently an alkyl group having 1 to 6 carbon atoms, provided that R 12 The number of carbon atoms and R 13 The total number of carbon atoms is 7 or less.)

[0054] In the above formula (4-1), m2 is preferably 0. In the above formula (4-2), R 11 is preferably an alkyl group having 1 to 4 carbon atoms. m3 is preferably an alkyl group having 2 to 4 carbon atoms. In the above formula (4-3), R 12 R preferably has 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group. 13 The carbon number is preferably 1 to 5, and more preferably 2 to 5.

[0055] Among the above, the specific solvent is preferably at least one selected from the group consisting of tetrahydrofuran, furan, diisopropyl ether, dibutyl ether, tert-butyl methyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether (diglyme), diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ether (triglyme), triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether (tetraglyme), ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, amyl acetate, methyl isobutyrate, and ethyl isobutyrate.

[0056] In the present production method, the specific solvent may be used alone as the polymerization solvent, or an organic solvent different from the specific solvent (hereinafter also referred to as "other solvent") may be used in combination. As the other solvent, a hydrocarbon compound having 3 to 8 carbon atoms can be preferably used.

[0057] Specific examples of hydrocarbon compounds having 3 to 8 carbon atoms include saturated or unsaturated chain hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, n-heptane, isooctane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, and 2-hexene; alicyclic hydrocarbons such as cyclohexane, cyclopentane, methylcyclopentane, methylcyclohexane, ethylcyclohexane, and cyclohexene; and aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene. Of these, aromatic hydrocarbons having 3 to 8 carbon atoms can be preferably used as the other solvent.

[0058] The proportion of the specific solvent in the polymerization solvent is preferably 0.2% by mass or more relative to the total amount of the polymerization solvent. By setting the proportion of the specific solvent within the above range, the polymerization reaction of the monomer having an ethylenically unsaturated bond can be sufficiently progressed in the presence of the anionic polymerization initiator and the organoaluminum compound. From the viewpoint of sufficiently progressing the polymerization reaction of the monomer, the proportion of the specific solvent is more preferably 0.3% by mass or more, and even more preferably 0.4% by mass or more, relative to the total amount of the polymerization solvent. There is no particular limitation on the upper limit of the proportion of the specific solvent in the polymerization solvent. The polymerization reaction of the monomer having an ethylenically unsaturated bond may be carried out in the presence of the anionic polymerization initiator and the organoaluminum compound using only the specific solvent as the polymerization solvent.

[0059] In order to maintain a balance between productivity and ease of polymerization control, the amount of solvent used in the polymerization is preferably 200 to 3,000 parts by mass per 100 parts by mass of the total of the monomers used in the polymerization.

[0060] The polymerization temperature is preferably within the range of -10°C to 50°C. According to the present production method, a polymer with a precisely controlled molecular weight can be obtained even when the polymerization temperature is set at a relatively high temperature of -10°C to 50°C. From the viewpoint of carrying out polymerization under as mild a temperature condition as possible while precisely controlling the molecular weight, the polymerization temperature is preferably -5°C or higher, more preferably -2°C or higher. From the viewpoint of suppressing side reactions and increasing the reaction rate, the polymerization temperature is preferably 40°C or lower, more preferably 30°C or lower, and even more preferably 25°C or lower. The polymerization reaction is preferably carried out under a pressure sufficient to maintain the monomers substantially in a liquid phase. The polymerization method may be either a batch method or a continuous method.

[0061] The number average molecular weight (Mn) of the polymer obtained by this production method is preferably 20,000 or more. A number average molecular weight (Mn) of 20,000 or more tends to result in a polymer with excellent strength, heat resistance, and processability. The number average molecular weight (Mn) of the polymer is preferably 22,000 or more, more preferably 24,000 or more. Furthermore, from the viewpoint of improving the flowability, processability, and flexibility of the polymer, the number average molecular weight (Mn) of the polymer obtained by this production method is preferably 3,000,000 or less, more preferably 1,000,000 or less. In this specification, the molecular weight of the polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0062] The molecular weight distribution (Mw / Mn) of the polymer obtained by the present production method is preferably 1.0 to 3.0. From the viewpoint of more precisely controlling the molecular weight and obtaining a polymer exhibiting high functionality, the molecular weight distribution (Mw / Mn) is preferably 2.7 or less, more preferably 2.3 or less, even more preferably 2.0 or less, still more preferably 1.8 or less, and even more preferably 1.7 or less.

[0063] The polymer obtained by the above-described production method has a highly controlled molecular weight, and such polymer can be used in a wide range of applications, such as optical components, electrical equipment, automotive components, construction components, and medical devices.

[0064] The present disclosure described above includes the following aspects [1] to [8]. [1] A method for producing a polymer, comprising polymerizing a monomer containing at least one compound selected from the group consisting of the compounds represented by the above formulas (1) to (4) in a solvent in the presence of an anionic polymerization initiator and a compound represented by the above formula (5), wherein the solvent contains a specific solvent which is at least one compound selected from the group consisting of ether compounds, ester compounds, ketone compounds, nitrile compounds, and amide compounds and does not have anionic polymerization properties. [2] The method for producing a polymer according to [1], wherein the specific solvent contains at least one compound selected from the group consisting of ether compounds and ester compounds, and the compound does not have anionic polymerization properties. [3] The method for producing a polymer according to [1] or [2], wherein the content of the specific solvent is 0.2 mass % or more based on the total amount of the solvent. [4] The method for producing a polymer according to any one of [1] to [3], wherein the anionic polymerization initiator is a salt of an anion of a conjugate acid having an acidity constant (pKa) of 10 or less in water at 25°C and an ammonium cation or a phosphonium cation. [5] The method for producing a copolymer according to [4], wherein the anion contained in the anionic polymerization initiator is a carboxylate ion, an azide ion, or a 2,4-dinitrophenol ion. [6] The method for producing a polymer according to any one of [1] to [5], wherein the polymerization temperature is in the range of -10 to 50°C. [7] The method for producing a polymer according to any one of [1] to [6], wherein the specific solvent is at least one selected from the group consisting of cyclic ethers having 3 to 6 carbon atoms, chain ethers having 3 to 12 carbon atoms, and chain esters having 3 to 8 carbon atoms. [8] The method for producing a polymer according to any one of [1] to [7], wherein the monomer comprises a compound represented by the above formula (1). [Example]

[0065] The present invention will be described in detail below based on examples, but is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified. The method for measuring the molecular weight of the polymer is as follows.

[0066] [Measurement of molecular weight of polymer]: Using a gel permeation chromatograph (trade name: HLC-8420GP, manufactured by Tosoh Corporation) and a differential refractometer as a detector, measurements were carried out under the following conditions, and the molecular weight was calculated as a standard polystyrene equivalent value. Column: 2 units of "GMHXL-SP" (manufactured by Tosoh Corporation), column temperature: 40°C Mobile phase: tetrahydrofuran, flow rate: 1.0 mL / min Sample concentration: 10mg / 20mL

[0067] 1. Preparation of anionic polymerization initiator (carboxylate compound) (Preparation of initiator 1) A dry recovery flask was charged with 19.9 g of a 10% methanol solution of tetrabutylammonium hydroxide (ammonium salt) and 0.79 g of pivalic acid, followed by heating at 50°C for 1 hour. Then, 10 mL of toluene was added and azeotropic dehydration was carried out. After three cycles of azeotropic dehydration, the atmosphere was purged with nitrogen, and 28 mL of dehydrated toluene was added. Activated molecular sieves were then placed inside, resulting in an approximately 0.25 M dehydrated toluene solution.

[0068] (Preparation of initiator 2) In a dry recovery flask, 19.9 g of a 10% methanol solution of tetrabutylammonium hydroxide as an ammonium salt and 0.48 g of acetic acid were added, and the same procedure as for initiator 1 was carried out to prepare an approximately 0.25 M dehydrated toluene solution.

[0069] (Preparation of initiator 3) In a dry recovery flask, 19.9 g of a 10% methanol solution of tetrabutylammonium hydroxide as an ammonium salt and 0.71 g of isobutyric acid were added, and the same procedure as for initiator 1 was carried out to prepare an approximately 0.25 M dehydrated toluene solution.

[0070] (Preparation of initiator 4) In a dry recovery flask, 28.5 g of a 10% methanol solution of tetrabutylammonium hydroxide as an ammonium salt and 0.98 g of benzoic acid were placed, and the same procedure as for initiator 1 was carried out to prepare an approximately 0.25 M dehydrated toluene solution.

[0071] 2. Preparation of aluminum catalyst (organoaluminum compound) (Preparation of Al catalyst 1) A dried Schlenk tube was purged with nitrogen, and 16.5 g of 2,6-di-tert-butylphenol was placed in it. After evacuating, anhydrous toluene was added to prepare a 2 M toluene solution. A separate dried Schlenk tube was charged with 18 mL of a 1.0 mol / L toluene solution of triisobutylaluminum, cooled to 0°C, and then a solution of 2,6-di-tert-butylphenol (2 molar equivalents of aluminum) was added dropwise. The mixture was left overnight at room temperature with stirring to prepare a 0.5 M dehydrated toluene solution of the Al catalyst.

[0072] (Preparation of Al catalyst 2) A dried Schlenk flask was purged with nitrogen, and 18.9 g of 2,6-di-tert-butyl-4-methoxyphenol was placed in it. The same procedure as for Al catalyst 1 was carried out to prepare a 0.5 M dehydrated toluene solution of the Al catalyst.

[0073] (Preparation of Al catalyst 3) A dried Schlenk flask was purged with nitrogen, and 17.6 g of 2,6-di-tert-butyl-4-methylphenol was placed in it. The same procedure as for Al catalyst 1 was carried out to prepare a 0.5 M dehydrated toluene solution of the Al catalyst.

[0074] (Preparation of Al catalyst 4) A dried Schlenk tube was purged with nitrogen, and 7.1 g of 2,6-di-tert-butylphenol was placed in it. After evacuating, anhydrous toluene was added to prepare a 2 M toluene solution. A separate dried Schlenk tube was charged with 15 mL of a 1.0 mol / L toluene solution of triethylaluminum, cooled to 0°C, and then a solution of 2,6-di-tert-butylphenol (2 molar equivalents of aluminum) was added dropwise. The mixture was left overnight at room temperature with stirring to prepare a 0.5 M dehydrated toluene solution of the Al catalyst.

[0075] 3. Polymer production Example 1 After purging the air in a dried two-neck flask with nitrogen, 13.0 g of dehydrated toluene (referred to as "TL" in Table 1), 0.05 g of dehydrated tetrahydrofuran (THF), and 1.5 g of ethyl acrylate were added and stirred. After cooling to 0 °C, 0.3708 g of Al catalyst 1 was added. While stirring, 0.515 g of initiator 1 was added and polymerization was initiated at 0 °C. After 5 min, 1.0 mL of a 20 vol% ethanol / toluene solution was added to terminate the reaction, yielding poly(ethyl acrylate). After polymerization, the reaction solution was analyzed by gas chromatography, and the conversion rate was calculated from the residual monomer. The reaction solution was also reprecipitated with methanol to extract the polymer, which was then redissolved in tetrahydrofuran and its molecular weight was calculated by gel permeation chromatography (GPC).

[0076] Example 2 Polyethyl acrylate was obtained in the same manner as in Example 1, except that the amount of tetrahydrofuran was changed to 0.11 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1. Example 3 Polyethyl acrylate was obtained in the same manner as in Example 1, except that the amount of tetrahydrofuran was changed to 0.22 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0077] Example 4 Polyethyl acrylate was obtained in the same manner as in Example 1, except that the amount of tetrahydrofuran was changed to 0.43 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1. Example 5 Polyethyl acrylate was obtained in the same manner as in Example 1, except that toluene was not used and the amount of tetrahydrofuran was changed to 13.3 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0078] Example 6 After replacing the air in a dried two-neck flask with nitrogen, 13.3 g of dehydrated tetrahydrofuran and 1.5 g of ethyl acrylate were added and stirred. After cooling to 0°C, 0.3708 g of Al catalyst 1 was added and, while stirring, 0.026 g of initiator 1 was added, and polymerization was initiated at 0°C. After 5 minutes, 1.0 mL of a 20 vol% ethanol solution in toluene was added to terminate the reaction, yielding poly(ethyl acrylate). After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0079] Example 7 Polyethyl acrylate was obtained in the same manner as in Example 6, except that the polymerization temperature was changed to 25° C. After the polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1. Example 8 Polyethyl acrylate was obtained in the same manner as in Example 6, except that the amount of initiator 1 added was 0.017 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0080] Example 9 Polyethyl acrylate was obtained in the same manner as in Example 8, except that the polymerization temperature was changed to 25° C. After the polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1. Example 10 Polyethyl acrylate was obtained in the same manner as in Example 1, except that tetrahydrofuran was replaced with dehydrated methyl isobutyrate (referred to as "MIB" in Table 1) and the amount of methyl isobutyrate used was 0.61 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0081] Example 11 Polyethyl acrylate was obtained in the same manner as in Example 10, except that toluene was not used and the amount of methyl isobutyrate was 13.4 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1. Example 12 Polyethyl acrylate was obtained in the same manner as in Example 1, except that tetrahydrofuran was replaced with dehydrated ethyl acetate (denoted as "EA" in Table 1) and the amount of ethyl acetate used was 0.26 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0082] Example 13 Polyethyl acrylate was obtained in the same manner as in Example 12, except that the amount of ethyl acetate was changed to 0.53 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0083] Example 14 Polyethyl acrylate was obtained in the same manner as in Example 12, except that the amount of ethyl acetate was changed to 1.32 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0084] Example 15 Polyethyl acrylate was obtained in the same manner as in Example 1, except that tetrahydrofuran was changed to diethylene glycol dimethyl ether (referred to as "DGDE" in Table 1) and the amount of diethylene glycol dimethyl ether used was 0.81 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0085] Example 16 Polyethyl acrylate was obtained in the same manner as in Example 1, except that tetrahydrofuran was changed to tetraethylene glycol dimethyl ether (referred to as "TGDME" in Table 1) and the amount of tetraethylene glycol dimethyl ether used was 1.33 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0086] Example 17 After replacing the air in a dried two-neck flask with nitrogen, 15.0 g of dehydrated diisopropyl ether (referred to as "DIPE" in Table 1) and 1.5 g of ethyl acrylate were added and stirred. After cooling to 0°C, 0.3708 g of Al catalyst 1 was added and, while stirring, 0.515 g of initiator 1 was added, and polymerization was initiated at 0°C. After 5 minutes, 1.0 mL of a 20 vol% ethanol solution in toluene was added to terminate the reaction, yielding poly(ethyl acrylate). After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0087] Example 18 Polyethyl acrylate was obtained in the same manner as in Example 4, except that initiator 1 was changed to initiator 2 and the amount of initiator 2 used was 0.452 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1. Example 19 Polyethyl acrylate was obtained in the same manner as in Example 4, except that initiator 1 was changed to initiator 3 and the amount of initiator 3 used was 0.494 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0088] Example 20 Polyethyl acrylate was obtained in the same manner as in Example 4, except that initiator 1 was changed to initiator 4 and the amount of initiator 4 used was 54.5 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1. Example 21 A polyethyl acrylate polymer was obtained in the same manner as in Example 4, except that Al catalyst 1 was changed to Al catalyst 2 and the amount of Al catalyst 2 used was 0.4161 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0089] Example 22 Polyethyl acrylate was obtained in the same manner as in Example 4, except that Al catalyst 1 was changed to Al catalyst 3, the amount of Al catalyst 3 used was 0.3921 g, and the polymerization temperature was 25° C. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1. Example 23 Polyethyl acrylate was obtained in the same manner as in Example 4, except that Al catalyst 1 was changed to Al catalyst 4 and the amount of Al catalyst 4 used was 0.3500 g. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0090] Example 24 Polyhexyl acrylate was obtained in the same manner as in Example 4, except that hexyl acrylate was used as the monomer instead of ethyl acrylate. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0091] Example 25 Polybutyl acrylate was obtained in the same manner as in Example 4, except that butyl acrylate was used as the monomer instead of ethyl acrylate. After polymerization, the reaction rate and molecular weight were calculated in the same manner as in Example 1.

[0092] (Comparative Example 1) Polymerization was carried out in the same manner as in Example 1, except that the amount of tetrahydrofuran was changed to 0.60 g and no Al catalyst was used. However, under these conditions, the polymerization reaction did not proceed, and the target polymer (polyethyl acrylate) could not be obtained.

[0093] The polymerization conditions in Examples 1 to 25 and Comparative Example 1, as well as the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the polymers obtained by polymerization, are shown in Table 1. In Comparative Example 1, the polymerization reaction did not proceed, so "-" is entered in the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) columns.

[0094] [Table 1]

[0095] In Table 1, the abbreviations for the monomers have the following meanings. M1: Ethyl acrylate M2: hexyl acrylate M3: Butyl acrylate

[0096] As can be seen from the results shown in Table 1, according to Examples 1 to 25, even when the polymerization of the monomers was carried out under mild temperature conditions, the number average molecular weight (Mn) increased depending on the amount of the anionic polymerization initiator, and polymers with sufficiently narrow molecular weight distributions were obtained.

Claims

1. The following formulas (1) to (4): 【Chemical 1】 (In formulas (1) to (4), R １ represents a hydrocarbyl group having 1 to 20 carbon atoms, which may be substituted with a heteroatom-containing group having at least one element selected from the group consisting of nitrogen, oxygen, sulfur, and halogen. ２ , R ３ and R ６ R each independently represents a hydrogen atom, a halogen atom, or a substituent having one or more carbon atoms. ４ and R ５ are each independently a hydrogen atom or a substituent having one or more carbon atoms, or R ４ and R ５ are combined together, R ４ and R ５ represents a ring structure formed together with the nitrogen atom to which R is bonded. ７ represents a divalent linking group. A monomer containing at least one selected from the group consisting of compounds represented by the following formula (5): 【Chemistry 2】 (In formula (5), Ar １ represents a monovalent group bonded to the oxygen atom in the formula via a benzene ring, in which a secondary carbon or a tertiary carbon is bonded to the carbon at the 2nd and 6th positions of the benzene ring, respectively, and a hydrogen atom, a chlorine atom, a fluorine atom, a hydrocarbyl group having 1 to 6 carbon atoms, or a hydrocarbyloxy group having 1 to 6 carbon atoms is bonded to the carbon at the 4th position. １０ represents an alkyl group having 2 to 10 carbon atoms. Polymerization is carried out in the presence of a compound represented by the formula: A method for producing a polymer, wherein the solvent contains a specific solvent that is at least one selected from the group consisting of ether compounds, ester compounds, ketone compounds, nitrile compounds, and amide compounds and does not have anionic polymerizability.

2. The method for producing a polymer according to claim 1 , wherein the specific solvent comprises at least one compound selected from the group consisting of ether compounds and ester compounds, the compound not being anionically polymerizable.

3. The method for producing a polymer according to claim 1 or 2, wherein the content of the specific solvent is 0.2 mass% or more based on the total amount of the solvent.

4. 3. The method for producing a polymer according to claim 1 or 2, wherein the anionic polymerization initiator is a salt of an anion of a conjugate acid having an acidity constant (pKa) of 10 or less in water at 25°C with an ammonium cation or a phosphonium cation.

5. 5. The method for producing a copolymer according to claim 4, wherein the anion contained in the anionic polymerization initiator is a carboxylate ion, an azide ion, or a 2,4-dinitrophenol ion.

6. The method for producing a polymer according to claim 1 or 2, wherein the polymerization temperature is in the range of -10 to 50°C.

7. 3. The method for producing a polymer according to claim 1, wherein the specific solvent is at least one selected from the group consisting of cyclic ethers having 3 to 6 carbon atoms, chain ethers having 3 to 12 carbon atoms, and chain esters having 3 to 8 carbon atoms.

8. The method for producing a polymer according to claim 1 or 2, wherein the monomer comprises a compound represented by the formula (1).

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