Method for producing vinyl polymer

Abstract

A vinyl polymer is produced by a method that includes a step for obtaining a polymer (P) having a halogen atom at a molecular terminal and containing a structural unit derived from a vinyl monomer and a step for reacting the polymer (P) with a carboxylate having an organic cation. The carboxylate is a quaternary ammonium salt, or a neutralization product of a carboxylic acid and an organic base having a boiling point of 200°C or lower.

Description

Method for producing vinyl polymers

[0001] [Cross-reference of related applications] This application claims priority under Japanese Patent Application No. 2024-207090, filed on 28 November 2024, which is incorporated herein by reference in its entirety. This disclosure relates to a method for producing vinyl polymers.

[0002] For industrial applications, vinyl polymers with crosslinkable functional groups are known. Recently, living radical polymerization, a polymerization method consisting of an initiation reaction and a growth reaction with no side reactions, has become widely used as a method for producing vinyl polymers, as it allows for the synthesis of polymers with well-controlled molecular weight distribution and molecular structure.

[0003] Vinyl polymers having crosslinkable functional groups at their molecular ends are widely used as curable resin compositions for producing cured products in various fields, such as paints, adhesives, sealants, molded articles, and rubber sheets. For example, Patent Document 1 discloses that a vinyl polymer having bromine ends is synthesized by atom transfer radical polymerization (ATRP), and the obtained vinyl polymer is reacted with potassium methacrylate in dimethylacetamide to obtain a vinyl polymer having (meth)acryloyl groups at its molecular ends.

[0004] Japanese Patent Publication No. 2000-72815

[0005] However, when vinyl polymers with bromine-terminated groups were treated with potassium methacrylate in a solvent other than dimethylacetamide, maintaining a high rate of introduction of the desired group at the molecular ends sometimes required a long time for the end modification treatment. In this case, there was concern that the productivity of vinyl polymers would decrease. Furthermore, when vinyl polymers with iodine atoms at the molecular ends were treated with potassium methacrylate to obtain modified products, discoloration of the resulting modified products sometimes became a problem.

[0006] This disclosure has been made in view of these circumstances, and its main purpose is to provide a method for producing a vinyl polymer that can shorten the processing time while maintaining a high introduction rate when modifying the molecular ends by introducing a desired group to the end of the molecule, and that can produce a vinyl polymer with less discoloration.

[0007] The present inventors have conducted diligent research and found that the above problems can be solved by using a specific compound as a modifying agent that acts on vinyl polymers having halogen atoms at their molecular ends. Specifically, the present disclosure provides the following vinyl polymer.

[0008] [1] A method for producing a vinyl polymer, comprising the steps of: obtaining a polymer (P) having halogen atoms at its molecular ends and containing structural units derived from vinyl monomers; and reacting the polymer (P) with a carboxylate salt having an organic cation, wherein the carboxylate salt is either a quaternary ammonium salt or a neutralized product of a carboxylic acid and an organic base having a boiling point of 200°C or less. [2] The method for producing a vinyl polymer according to [1], wherein the halogen atom is an iodine atom. [3] The method for producing a vinyl polymer according to [1] or [2], wherein the organic base has a nitrogen atom. [4] Polar component δ in the Hansen solubility parameter ｐ 1.0 (cal / cm) ０．５ A method for producing a vinyl polymer according to any one of [1] to [3], comprising reacting the polymer (P) and the carboxylate in the above solvent.

[0009] According to this disclosure, when modifying molecular ends by introducing a desired group, it is possible to shorten the processing time while maintaining a high introduction rate. Furthermore, it is possible to obtain vinyl polymers with less coloration.

[0010] The following provides a detailed explanation of this disclosure. In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate. "(meth)acrylo" means acrylo and / or methacrylo.

[0011] 《Method for Producing Vinyl Polymers》 The method for producing vinyl polymers according to this disclosure (hereinafter also simply referred to as "this manufacturing method") includes the following first and second steps. First step: A step to obtain a polymer (P) having halogen atoms at the molecular ends and containing structural units derived from vinyl monomers. Second step: A step to react the polymer (P) with a carboxylate salt having an organic cation. Each step of this manufacturing method will be described in detail below.

[0012] <First Step> In the first step, the method of obtaining the polymer (P) is not particularly limited, as long as a vinyl polymer having halogen atoms at its molecular ends can be obtained. When obtaining the polymer (P) in the first step by polymerizing vinyl monomers, any known polymerization method can be used as appropriate. Living radical polymerization, which involves precision polymerization in the presence of a control agent containing halogen atoms, is preferred because it can produce polymers with a narrow molecular weight distribution and can easily produce polymers with halogen atoms introduced at their molecular ends. Specifically, among living radical polymerization methods, atom transfer radical polymerization (ATRP method), reversible transfer catalytic polymerization (RTCP method), reversible coordination-mediated polymerization (RCMP method), and iodine transfer polymerization are preferred, with iodine transfer polymerization being more preferred because it is an inexpensive yet highly safe controlled radical polymerization method and is highly practical.

[0013] Examples of halogen atoms (hereinafter also referred to as "terminal halogens") that polymer (P) may have at its molecular ends include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Of these, bromine atoms or iodine atoms are preferred, and iodine atoms are particularly preferred, because they allow for a higher rate of introduction of groups derived from the anionic portion of the carboxylate salt when the terminal halogens of polymer (P) are used to modify the ends of polymer (P) in the subsequent second step.

[0014] The vinyl monomer constituting the polymer (P) is not particularly limited, and various vinyl monomers having radical polymerizability can be used. Examples of vinyl monomers include (meth)acrylic acid ester compounds, aromatic vinyl compounds, unsaturated carboxylic acids, unsaturated acid anhydrides, hydroxyl group-containing vinyl compounds, amino group-containing vinyl compounds, amide group-containing vinyl compounds, alkoxy group-containing vinyl compounds, nitrile group-containing vinyl compounds, maleimide compounds, and the like. One of these vinyl monomers may be used alone, or two or more may be used in combination.

[0015] Specific examples of vinyl monomers include the following compounds: (meth)acrylate ester compounds include alkyl (meth)acrylate ester compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, amyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-dodecyl (meth)acrylate, and n-octadecyl (meth)acrylate; Examples include aliphatic cyclic ester compounds of (meth)acrylic acid such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; and aromatic ester compounds of (meth)acrylic acid such as phenyl methacrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, and 3-phenoxypropyl (meth)acrylate.

[0016] As the aromatic vinyl compound, styrene-based compounds such as styrene, α-methylstyrene, β-methylstyrene, vinylxylene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, p-n-butylstyrene, p-isobutylstyrene, p-t-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, and divinylbenzene, and vinylnaphthalene, etc. can be mentioned.

[0017] As the unsaturated carboxylic acid, (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamic acid, monoalkyl esters of unsaturated dicarboxylic acids (monoalkyl esters of maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.) and the like can be mentioned. As the unsaturated acid anhydride, for example, maleic anhydride, itaconic anhydride, citraconic anhydride and the like can be mentioned.

[0018] As the vinyl compound containing a hydroxy group, hydroxyalkyl (meth)acrylate compounds such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; polyalkylene glycol mono(meth)acrylate compounds such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate and polyethylene glycol-polypropylene glycol mono(meth)acrylate; unsaturated alcohols such as allyl alcohol; N-substituted maleimide compounds such as N-(4-hydroxyphenyl)maleimide; and hydroxyl group-containing styrene-based compounds such as o-hydroxystyrene, m-hydroxystyrene and p-hydroxystyrene and the like can be mentioned.

[0019] Examples of the amino group-containing vinyl compound include dimethylaminomethyl (meth)acrylate, diethylaminomethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 2-(di-n-propylamino)ethyl (meth)acrylate, 2-dimethylaminopropyl (meth)acrylate, 2-diethylaminopropyl (meth)acrylate, 2-(di-n-propylamino)propyl (meth)acrylate, 3-dimethylaminopropyl (meth)acrylate, 3-diethylaminopropyl (meth)acrylate, 3-(di-n-propylamino)propyl (meth)acrylate, and the like.

[0020] Examples of the amide group-containing vinyl compound include (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N-methylol (meth)acrylamide, and the like. Examples of the alkoxy group-containing vinyl compound include, for example, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(n-propoxy)ethyl (meth)acrylate, 2-(n-butoxy)ethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 2-(n-propoxy)propyl (meth)acrylate, 2-(n-butoxy)propyl (meth)acrylate, and the like.

[0021] Examples of the nitrile group-containing vinyl compound include 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, 2-ethyl-6-cyanohexyl (meth)acrylate, 8-cyanooctyl (meth)acrylate, (meth)acrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile, and the like.

[0022] Examples of maleimide compounds include maleimides and N-substituted maleimide compounds. Examples of N-substituted maleimide compounds include N-methylmaleimide, N-ethylmaleimide, N-n-propylmaleimide, N-isopropylmaleimide, N-n-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N-pentylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, and N-stearylmaleimide, which are N-alkyl-substituted maleimide compounds; N-cyclopentylmaleimide and N Examples include N-cycloalkyl-substituted maleimide compounds such as cyclohexylmaleimide; N-aralkyl-substituted maleimide compounds such as N-benzylmaleimide; 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, and N-(4-bromophenyl)maleimide. In addition to the above compounds, dialkyl esters of unsaturated dicarboxylic acids, vinyl ester compounds, vinyl ether compounds, etc., can also be used as monomers constituting the polymer (P).

[0023] The polymer (P) and the final product, a vinyl polymer, are preferably (meth)acrylic polymers because they can be produced relatively easily by living radical polymerization methods such as iodine transfer polymerization and ATRP, they offer a high degree of freedom in monomer selection, and they have excellent properties such as flexibility and weather resistance, making them applicable to a wide range of uses. When the polymer (P) (and by extension, the vinyl polymer obtained by this production method) is a (meth)acrylic polymer, the amount of (meth)acrylic compound among the monomers constituting the polymer is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, relative to the total amount of monomers constituting the polymer.

[0024] When the polymer (P) is a (meth)acrylic polymer, from the viewpoint of ease of application of the living radical polymerization method, it is more preferable that the polymer (P) contains a structural unit derived from a compound represented by the following general formula (1). CH ２ =CR １ -C(=O)-O-(R ２ O) ｎ -R ３ …(1) (In the general 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, and R ３ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 100.)

[0025] Specific examples of the compound represented by the above general formula (1) include the (meth)acrylic ester compounds, alkoxy group-containing vinyl compounds, (meth)acrylic acid hydroxyalkyl compounds, and polyalkylene glycol mono(meth)acrylate compounds exemplified above. Among these, it is more preferable to contain a (meth)acrylic ester compound in that a vinyl polymer having good various properties such as heat resistance can be obtained.

[0026] The polymer (P) may be a homopolymer obtained by polymerizing one kind of monomer, or may be a copolymer obtained by polymerizing two or more kinds of monomers. The type of the copolymer is not particularly limited, and examples include a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

[0027] When polymer (P) is obtained by iodine transfer polymerization, polymer (P) can be obtained by polymerizing vinyl monomers (specifically, by living radical polymerization) in the presence of an iodine-based polymerization controller and a radical polymerization initiator. In iodine transfer polymerization, an iodine compound (i.e., an iodine-based polymerization controller) acts as an exchange chain transfer agent for radicals generated by a free radical polymerization initiator, and polymerization proceeds. At this time, the iodine-based polymerization controller functions as a living radical polymerization controller that precisely controls the molecular weight of the polymer in the vinyl monomer polymerization system. This makes it possible to obtain a polymer with a narrow molecular weight distribution.

[0028] The iodine-based polymerization control agent is not particularly limited, as long as it functions as a living radical polymerization control agent that precisely controls the molecular weight and molecular weight distribution of the polymer (P). Examples of iodine-based polymerization control agents include monofunctional control agents having one iodine group in one molecule; difunctional control agents having two iodine groups in one molecule; and polyfunctional control agents having three or more iodine groups in one molecule. For example, by performing polymerization in the presence of a monofunctional control agent, a polymer having an iodine group at one end of the polymer chain can be obtained, and by performing polymerization in the presence of a difunctional control agent, a polymer having iodine groups at both ends of the polymer chain (telechelic polymer) can be obtained. Furthermore, by performing polymerization in the presence of a polyfunctional control agent, a branched polymer can be obtained.

[0029] Specific examples of monofunctional iodine-based polymerization regulators include α-iodoester compounds such as ethyl 2-iodoethyl, ethyl 2-iodopropionate, ethyl 2-iodobutyrate, and ethyl 2-iodoisobutyrate; α-iodocarboxylic acids such as 2-iodoacetic acid, 2-iodopropionic acid, 2-iodobutyrate, and 2-iodoisobutyrate; α-iodlactone compounds such as α-iodo-γ-butyrolactone; α-iodoamide compounds such as 2-iodopropionamide; α-iodonitrile compounds such as 2-iodoacetonitrile and 2-iodopropionitrile; α-iodoketone compounds such as 2-iodoacetophenone; and benzyl iodide compounds such as benzyl iodide, (1-iodoethyl)benzene, and 4-nitrobenzyl iodide.

[0030] Specific examples of bifunctional control agents include 1,4-bis(iodomethyl)benzene, diethyl 2,5-diiodoadipate, 1,4-bis(1'-iodoethyl)benzene, and ethylene glycol bis(2-iodoisobutyrate). Specific examples of polyfunctional control agents include glycerol tris(2-iodoisobutyrate) and 1,3,5-tris(1'-iodoethyl)benzene. As iodine-based polymerization control agents, one of these may be used alone, or two or more may be used in combination.

[0031] The amount of iodine-based polymerization control agent used can be appropriately set according to the molecular weight of the desired vinyl polymer. The amount of iodine-based polymerization control agent used is, for example, 0.001 to 0.5 parts by mass per 100 parts by mass of the total amount of monomers used for polymerization.

[0032] As radical polymerization initiators, known radical polymerization initiators such as azo compounds, organic peroxides, and persulfates can be used. Among these, azo compounds are preferred because they are easy to handle safely and less likely to cause side reactions during radical polymerization. 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-carbonitride), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], and 2,2'-azobis(N-butyl-2-methylpropionamide). One type of radical polymerization initiator may be used, or two or more types may be used in combination.

[0033] The amount of radical polymerization initiator used is not particularly limited, but from the viewpoint of obtaining polymers with a smaller molecular weight distribution, it is preferable to use 0.5 mol or less, and more preferably 0.2 mol or less, per mol of iodine-based polymerization regulator. Furthermore, 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, and more preferably 0.05 mol or more, per mol of iodine-based polymerization regulator. The amount of radical polymerization initiator used per mol of iodine-based polymerization regulator is preferably 0.01 to 0.5 mol, and more preferably 0.05 to 0.2 mol.

[0034] The polymerization reaction is preferably carried out in a polymerization solvent using a polymerization solvent known for living radical polymerization. In the case of solution polymerization, the solvent, monomer and iodine-based polymerization control agent are charged into the reactor, a radical polymerization initiator is added, and polymerization is carried out by heating as needed to obtain the target polymer (P). The method of charging each raw material may be a batch-type initial batch charging in which all raw materials are charged at once, a semi-continuous charging in which at least some of the raw materials are continuously supplied into the reactor, or a continuous polymerization method in which all raw materials are continuously supplied and the product is continuously withdrawn from the reactor at the same time. In the continuous polymerization method, a tubular type, a tower type, a continuous stirring tank type (CSTR), or a combination thereof may be used. Of these, the tubular type and the tower type are preferred in that they can narrow the molecular weight distribution of the resulting vinyl polymer.

[0035] When polymerization is carried out in a polymerization solvent, the polymerization solvent used is preferably an organic solvent capable of dissolving monomers. Examples of organic solvents used for polymerization include aromatic compounds such as benzene, toluene, xylene, and anisole; esters such as methyl acetate, propyl acetate, and butyl acetate; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and nitriles such as acetonitrile. The polymerization solvent may be used alone or in combination of two or more. When hydrophilic monomers are used in polymerization, alcohols, water, etc., can be used as the polymerization solvent. The amount of polymerization solvent used is preferably 5 to 200 parts by mass, and more preferably 10 to 100 parts by mass, per 100 parts by mass of the total amount of monomers used for polymerization. Using 100 parts by mass or less of polymerization solvent is preferable because it allows for a high polymerization rate in a short time.

[0036] In the polymerization reaction by living radical polymerization, the reaction temperature is preferably 40°C to 100°C, more preferably 45°C to 90°C, and even more preferably 50°C to 80°C. A reaction temperature of 40°C or higher is preferable because it allows the polymerization reaction to proceed smoothly, and a reaction temperature of 100°C or lower is preferable because it suppresses the thermal decomposition of iodine-based polymerization control agents and side reactions, as well as relaxing the restrictions on the polymerization initiators and solvents that can be used. The reaction time can be appropriately set depending on the monomers used, but is preferably 1 hour to 48 hours, and more preferably 2 hours to 24 hours.

[0037] The solution containing the polymer (P) obtained by the above polymerization may be used as is in the next second step, or the polymer (P) may be isolated and / or purified from the solution containing the polymer (P) before being used in the next second step. The isolation and purification of polymer (P) can be carried out by employing known methods as appropriate.

[0038] <Step 2> In Step 2, a carboxylate salt containing an organic cation is used as a modifying agent, and the polymer (P) obtained in Step 1 is reacted with the carboxylate salt containing the organic cation. Through this reaction, a modified product can be obtained in which the anionic portion of the carboxylate salt is introduced to the molecular ends of polymer (P) by utilizing the terminal halogen of polymer (P). Furthermore, according to this manufacturing method including Step 2, a modified product with less coloration can be obtained. Moreover, there are fewer restrictions on the solvents that can be used when modifying the ends of vinyl polymers, and general-purpose solvents can be used as appropriate.

[0039] In the second step, the carboxylate salt reacted with the polymer (P) (hereinafter also referred to as the "specific carboxylate salt") is a quaternary ammonium salt, or a neutralized product of a carboxylic acid and an organic base with a boiling point of 200°C or lower. The specific carboxylate salt can preferably be a compound represented by the following general formula (2): R-COO － Z ＋ …(2) (In general formula (2), R is a monovalent organic group, Z ＋ (This is an organic cation derived from a quaternary ammonium ion or an organic base with a boiling point of 200°C or lower.)

[0040] The quaternary ammonium ion constituting the specific carboxylate is not particularly limited, and the general formula is: N ＋ (R Ａ ) ４ Polyatomic ions represented by and polyatomic ions having nitrogen-containing heterocycles can be used. Here, R Ａ Examples include alkyl groups, aryl groups, and aralkyl groups. Note that the four R groups in the formula... Ａ These may be the same or different. Specific examples of quaternary ammonium ions include, for example, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, benzyltrimethylammonium ion, benzyltriethylammonium ion, and hexadecyltrimethylammonium ion, dimethylpiperidinium ion, cetylpyridinium ion, and the like.

[0041] As organic bases with a boiling point of 200°C or lower, basic compounds containing a nitrogen atom can be preferably used. Examples of such organic bases include primary amines such as monoethylamine, monobutylamine, ethanolamine, ethylenediamine, and aniline; secondary amines such as diethylamine and dibutylamine; tertiary amines such as trimethylamine, triethylamine, tripropylamine, tetramethylethylenediamine, and N-methylmorpholine; nitrogen-containing aromatic heterocyclic compounds such as pyridine; and guanidines such as guanidine and tetramethylguanidine (TMG). As organic bases with a boiling point of 200°C or lower, one of these may be used, or two or more may be used in combination.

[0042] From the viewpoint of obtaining a vinyl polymer with sufficiently reduced discoloration, the boiling point of the organic base is preferably 190°C or lower, more preferably 180°C or lower, and even more preferably 175°C or lower. The lower limit of the boiling point of the organic base is not particularly limited. The boiling point of the organic base may be, for example, 5°C or higher, or 10°C or higher. The boiling point range of the organic base is preferably 5 to 190°C, and more preferably 5 to 180°C. In this specification, the boiling point of the compound is the value at 1 atmosphere.

[0043] Furthermore, as the organic base constituting the specific carboxylate, a compound having an acid dissociation constant (pKa) of 10.5 or higher in water at 25°C can preferably be used. From the viewpoint of sufficiently suppressing the coloration of vinyl polymers, the pKa of the organic base constituting the specific carboxylate is more preferably 11.0 or higher, even more preferably 12.0 or higher, even more preferably 12.5 or higher, even more preferably 13.0 or higher, and particularly preferably 13.5 or higher. Regarding the acid dissociation constant (pKa), if two or more dissociation steps are possible for the target organic base, the first dissociation should be considered. Therefore, for organic bases where two or more dissociation steps are possible, an electrically neutral molecule (B) with one hydrogen ion (H) ＋ ) accepts a monovalent cation (BH ＋ This is the acid dissociation constant (pKa) at the stage where ) occurs.

[0044] Anions (R-COO) possessed by specific carboxylate salts －The organic group R in the general formula (2) above is not particularly limited, as long as it can be a counterion of a quaternary ammonium ion or an organic cation derived from an organic base with a boiling point of 200°C or less. Specific examples of the monovalent organic group represented by R in the general formula (2) above include monovalent hydrocarbon groups which may have substituents, and groups which have a heterocyclic structure. Examples of monovalent hydrocarbon groups include saturated or unsaturated chain hydrocarbon groups, saturated or unsaturated alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. Examples of heterocyclic structures include piperazine structures, pyridine structures, tetrahydrofuran structures, purine structures, and thiophene structures. Examples of substituents include hydroxyl groups, amino groups, thiol groups, epoxy groups, oxazoline groups, silanol groups, crosslinkable silyl groups (alkoxysilyl groups, etc.), cyano groups, alkoxy groups, and isocyanate groups.

[0045] Specific examples of carboxylic acids that constitute the anion of a particular carboxylate include, for example, saturated chain carboxylic acids such as acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid; unsaturated chain carboxylic acids such as (meth)acrylic acid, 2-methyl-3-butenoic acid, 4-pentenoic acid, 5-hexenoic acid, 8-nonenic acid, 9-decenoic acid, and 10-undecenoic acid; alicyclic carboxylic acids such as cyclopentaneic acid, cyclohexanecarboxylic acid, and 4-methylcyclohexanecarboxylic acid; aromatic carboxylic acids such as phenylacetic acid, o-tolylacetic acid, m-tolylacetic acid, p-tolylacetic acid, 4-methoxyphenylacetic acid, and 2-phenylbutyric acid; substituent-containing carboxylic acids such as glycolic acid, β-hydroxy acid, γ-hydroxy acid, δ-hydroxy acid, lactic acid, glyceric acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, and 2-aminoacetic acid; heterocyclic carboxylic acids such as isonicotinic acid; and the like.

[0046] Quaternary ammonium salts are particularly preferred as specific carboxylate salts because they can shorten the time required for polymer terminal modification while maintaining a high rate of introduction of terminal groups using terminal halogens of the polymer (P).

[0047] In the reaction between polymer (P) and a specific carboxylate, the amount of specific carboxylate used is preferably 0.5 mol equivalent or more relative to the terminal halogen of polymer (P). By setting the amount of specific carboxylate within the above range, terminal modification of polymer (P) by the specific carboxylate can be efficiently carried out. From this viewpoint, the amount of specific carboxylate used is more preferably 1.0 mol equivalent or more, and even more preferably 1.2 mol equivalent or more, relative to the terminal halogen of polymer (P). Furthermore, from the viewpoint of minimizing the amount of unreacted specific carboxylate remaining in the final product, the amount of specific carboxylate used is preferably 30 mol equivalent or less, more preferably 25 mol equivalent or less, and even more preferably 20 mol equivalent or less, relative to the terminal halogen of polymer (P).

[0048] The preferred range for the amount of specific carboxylate used can be set by appropriately combining the preferred upper and lower limits described above. The preferred range for the amount of specific carboxylate used is, for example, 0.5 to 30 mol equivalents, and more preferably 1.0 to 25 mol equivalents.

[0049] The reaction between the polymer (P) and the specific carboxylate salt is preferably carried out in a solvent. Examples of solvents used in the reaction between the polymer (P) and the specific carboxylate salt (hereinafter also referred to as the "reaction solvent") include nitriles such as acetonitrile; esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ethers such as methyl orthoformate, trimethyl orthoacetate, anisole, tetrahydrofuran, and dioxane; aromatic hydrocarbons such as benzene, toluene, and xylene; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and the like.

[0050] From the viewpoint of rapidly advancing the reaction between the polymer (P) and a specific carboxylate salt, and shortening the time required for polymer terminal modification, the reaction solvent is selected based on the polar component δ in the Hansen solubility parameter. ｐ 0.5 (cal / cm) ０．５It is preferable to use the solvents described above. Here, the Hansen solubility parameter is defined as the Hildebrand solubility parameter (SP value: δ) with the dispersion force term (δ). d ), polar term (δ ｐ ) and hydrogen bonding term (δ h ) is an index that takes into account the polarity of physical properties by dividing it into three components, and is "δ ２ = (δ d ) ２ + (δ ｐ ) ２ + (δ h ) ２ There is a relationship between the two. In this specification, the polar component δ in the Hansen solubility parameter of the solvent is defined as follows. ｐ This value was calculated using the method described in the document "C. M. Hansen, 'The three-dimensional solubility parameter.' Danish Technical: Copenhagen 14 (1967)."

[0051] Polarity component δ in the Hansen solubility parameter of the reaction solvent ｐ This method has a high effect in shortening the time required for polymer end modification, with a value of 1.0 (cal / cm). ０．５ The above is more preferable, 1.5 (cal / cm) ０．５ The above is even more preferable, 1.8 (cal / cm) ０．５ The above is even more preferable, 2.0 (cal / cm) ０．５ The above is even more preferable, 2.5 (cal / cm) ０．５ The above is particularly preferred. The polar component δ in the Hansen solubility parameter of the reaction solvent. ｐ There is no particular upper limit; for example, 12.0 (cal / cm³) ０．５ The following applies:

[0052] The reaction solvent may be used alone or as a mixture of two or more. When a mixture of two or more reaction solvents is used, the polar component δ of the Hansen solubility parameter of the mixture solvent is also considered. ｐ This is the polar component δ of each solvent contained in the mixed solvent. ｐIt is preferable that the summation average of the values ​​falls within the above preferred range. The polar component δ in the Hansen solubility parameter of the reaction solvent ｐ A preferred range is, for example, 1.0 to 12.0 (cal / cm). ０．５ The range is 1.5 to 12.0 (cal / cm). ０．５ It is preferable that it be so.

[0053] Since it is highly effective in shortening the time required for polymer end modification, at least one selected from the group consisting of nitriles, esters, and ethers can be preferably used as the reaction solvent. Among these, at least one selected from the group consisting of nitriles, esters, and ethers, which has a polar component δ in the Hansen solubility parameter, is preferable. ｐ 1.0 (cal / cm) ０．５ The solvents mentioned above can be used with particular preference. Furthermore, this manufacturing method, which modifies the end of the polymer (P) using a specific carboxylate, is advantageous because it allows the use of various organic solvents as the solvent for modification, thus limiting the constraints on the reaction solvent used.

[0054] The amount of reaction solvent used is preferably 5 to 800 parts by mass, and more preferably 10 to 500 parts by mass, per 100 parts by mass of polymer (P), from the viewpoint of increasing the reaction efficiency between polymer (P) and the specific carboxylate. The reaction temperature when reacting polymer (P) and the specific carboxylate is, for example, 20°C to 100°C, and preferably 30 to 95°C, from the viewpoint of retaining the end groups introduced into polymer (P) and suppressing discoloration of vinyl polymers. The reaction time is, for example, 0.1 to 24 hours, and preferably 0.1 to 12 hours. According to this manufacturing method in which the end groups of polymer (P) are modified using the specific carboxylate, even when the reaction time between polymer (P) and the specific carboxylate is, for example, 6 hours or less, or for example, 3 hours or less, the end groups of polymer (P) can be modified with a high introduction rate. Therefore, when modifying the end groups of vinyl polymers, it is possible to sufficiently shorten the time required for end group modification of the polymer while maintaining a high introduction rate of end groups. Furthermore, discoloration of the modified product can be suppressed.

[0055] These reactions can yield vinyl polymers in which terminal groups derived from specific carboxylates are introduced at the molecular ends. When isolating and / or purifying the vinyl polymer obtained from the reaction in the second step, known methods can be appropriately employed for these processes.

[0056] The modified vinyl polymer may have end groups derived from a specific carboxylate at some of its molecular ends, or at all of its molecular ends. For example, if the vinyl polymer is a linear polymer, it may have end groups derived from a specific carboxylate at only one end, or at both ends. For the vinyl polymer, the average number of end groups derived from a specific carboxylate per molecule is, for example, 0.3 or more, and may range from 0.3 to 4.0.

[0057] To reduce the discoloration of vinyl polymers, it is preferable to keep the content of transition metal atoms in the vinyl polymer as low as possible. Specifically, the transition metal atom content in the vinyl polymer is preferably 1000 ppm or less, more preferably 100 ppm or less, even more preferably 10 ppm or less, and particularly preferably 2 ppm or less. In this specification, "transition metal atom content" refers to the total amount of transition metal atoms contained in the vinyl polymer, which can be quantified by ICP emission spectrometry.

[0058] The number-average molecular weight (Mn) of the vinyl polymer obtained by this manufacturing method, measured by gel permeation chromatography (GPC) in terms of polystyrene, is, for example, in the range of 2,000 to 1,000,000. When Mn is 2,000 or more, it is easier to express the desired properties in the vinyl polymer. Furthermore, when Mn is 1,000,000 or less, it is preferable in that it is possible to sufficiently ensure processability such as coating properties and handling properties. The Mn of the vinyl polymer is preferably 5,000 or more, and more preferably 8,000 or more. The upper limit of Mn for the vinyl polymer is preferably 800,000 or less, and more preferably 600,000 or less. The preferred range of Mn for the vinyl polymer can be determined by appropriately combining the upper and lower limits described above. The Mn of the vinyl polymer is preferably 5,000 to 800,000, and more preferably 8,000 to 600,000.

[0059] The weight-average molecular weight (Mw) of the vinyl polymer, measured by GPC in terms of polystyrene, is, for example, in the range of 2,000 to 1,000,000. The Mw of the vinyl polymer is preferably 5,000 or more, and more preferably 8,000 or more. The upper limit of the Mw of the vinyl polymer is preferably 800,000 or less, and more preferably 700,000 or less. The range of Mw for the vinyl polymer is preferably 5,000 to 800,000, and more preferably 8,000 to 600,000.

[0060] The molecular weight distribution (Mw / Mn) of the vinyl polymer is preferably 3.0 or less, as this facilitates the expression of desired properties in the vinyl polymer. More preferably, the molecular weight distribution (Mw / Mn) is 2.5 or less, and even more preferably 2.0 or less. The lower limit of the molecular weight distribution (Mw / Mn) is not particularly limited, but from the viewpoint of ease of manufacture, it is, for example, 1.01 or more.

[0061] The vinyl polymers obtained by the manufacturing method of this disclosure can be used in a wide range of applications. Specifically, they can be applied to various uses such as sealants, adhesives, sealants, paints, dispersants, industrial rubbers, binders, and coatings. Application fields include civil engineering and construction materials, automotive parts, home appliance and office automation equipment parts, medical equipment parts, packaging materials, daily necessities, electric wires, and general merchandise.

[0062] The present invention will be described in detail below based on the following examples. However, the present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass," respectively, unless otherwise specified.

[0063] The measurement and evaluation methods for each property of vinyl polymers are shown below. (1) Molecular weight measurement For the vinyl polymers obtained in each example and comparative example, gel permeation chromatography (GPC) was performed under the conditions described below to obtain the number-average molecular weight (Mn) and weight-average molecular weight (Mw) in polystyrene equivalent. The molecular weight distribution (Mw / Mn) was also calculated from the obtained values. ○ Measurement conditions Column: TSKgel SuperMultiporeHZ-M manufactured by Tosoh × 4 Solvent: Tetrahydrofuran Temperature: 40℃ Detector: RI Flow rate: 600 μL / min

[0064] (2) Average number of terminal groups of vinyl polymers For the vinyl polymers obtained in each example and comparative example, １ The average number of end groups was calculated using the following formula based on the integral values ​​measured by 1H-NMR spectroscopy and the number-average molecular weight (Mn) obtained from GPC measurements: Average number of end groups of vinyl polymer = (number-average molecular weight) / [(integral value derived from constituent monomers) / (integral value derived from end groups) × (molecular weight of constituent monomers)]

[0065] (3) Appearance of vinyl polymers The degree of coloration of the vinyl polymers obtained in each example and comparative example was visually confirmed.

[0066] [Synthesis Example 1 (Synthesis of 1,4-bis(iodomethyl)benzene (Bz-II))] Under a nitrogen atmosphere, p-xylene-α,α'-diol (62.5 mmol, 8.64 g) and NaI (250 mmol, 37.5 g) were added and dissolved in anhydrous acetonitrile (500 mL). BF was added at room temperature. ３ The ether complex (250 mmol, 30.8 mL) was slowly added dropwise. After the addition was complete, the mixture was allowed to react at room temperature for 30 minutes. The reaction mixture was poured into ice water (250 g) and stirred, and 20% sodium thiosulfate (250 mL) was added and the mixture was transferred to a separatory funnel. The mixture was extracted with toluene (3 × 500 mL), and the organic layer was washed in the order of distilled water (2 × 200 mL) and saturated brine (200 mL). The mixture was dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated using a rotary evaporator. The resulting crude product was purified by column chromatography.

[0067] [Synthesis Example 2 (Synthesis of Tetrabutylammonium Acrylate (hereinafter also referred to as "TBAA"))] Acrylic acid (22.98 g) was added dropwise to a 40% methanol solution of tetrabutylammonium hydroxide (206 g) and stirred at room temperature for 2 hours. The reaction mixture was dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated using a rotary evaporator. The concentrated solution was vacuum-dried to obtain a white solid of TBAA.

[0068] ≪Production and Evaluation of Vinyl Polymers≫ (1) Production of Polymer (P) [Synthesis Example 3 (Production of Polymer 1)] Bz-II (17.90 g), 2,2'-azobis-2-methylbutyronitrile (hereinafter also referred to as "ABN-E") (0.24 g), n-butyl acrylate (500 g), and anisole (47.3 g) were charged into a 1 L flask equipped with a stirrer and thermometer. The mixture was thoroughly degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 70°C. After 4 hours, the mixture was cooled to room temperature to stop the reaction. After reprecipitation and purification of the obtained solution using methanol, polymer 1 was obtained by vacuum drying (first step). The molecular weight of the obtained polymer 1 was Mn 11,000, Mw 16,100, and Mw / Mn 1.45, as measured by GPC (gel permeation chromatography) (polystyrene equivalent).

[0069] (2) Modification of polymer (P) [Example 1] As shown in Table 1, polymer 1 (100 g) and acetonitrile (25.0 g) were placed in a 1 L flask equipped with a stirrer and thermometer, and polymer 1 was dissolved. After dissolving polymer 1, a pre-mixed mixture of acrylic acid (13.1 g), tetramethylguanidine (hereinafter also referred to as "TMG") (10.5 g), and acetonitrile (41.7 g) was added to the flask containing the polymer 1 solution, and the mixture was heated in a 70°C constant temperature bath for 2.1 hours (second step). Ethyl acetate (166.7 g) was added to the obtained solution to dilute it. Then, pure water (350.0 g) was added and stirred for 30 minutes. After stirring, it was allowed to stand for 30 minutes and the lower aqueous layer was removed. Further pure water (350.0 g) was added and stirred for 30 minutes. After stirring, it was allowed to stand for 30 minutes and the lower aqueous layer was removed. The obtained solution was vacuum-dried at 90°C for 16 hours to obtain a vinyl polymer (hereinafter also referred to as "modified polymer 1"). The molecular weight of modified polymer 1 was Mn 11,100, Mw 16,300, and Mw / Mn 1.46. The average number of terminal groups in modified polymer 1 was 2.0 (i.e., the rate of acryloyl group introduction to the terminals was 100%). Visual inspection of the degree of coloration of modified polymer 1 revealed that it was colorless.

[0070] [Examples 2-7 and Comparative Examples 2 and 3] As shown in Table 1, the same procedure as in Example 1 was carried out except that the type and amount of carboxylic acid, organic base and solvent, and the reaction time were changed to obtain modified compounds 2-7, modified compound 12, and modified compound 13. The molecular weight, average number of terminal groups, and degree of coloration of each modified compound are shown in Table 1.

[0071] [Examples 8-10 and Comparative Example 1] Polymer 1 and acetonitrile were placed in a 1 L flask equipped with a stirrer and thermometer, according to the amounts listed in Table 1, and Polymer 1 was dissolved. After dissolution, TBAA or potassium acrylate (AK) was added according to the amounts listed in Table 1, and the mixture was heated in a constant temperature bath at the temperature and time listed in Table 1. The resulting solution was diluted with ethyl acetate (166.7 g). Then, pure water (350.0 g) was added and the mixture was stirred for 30 minutes. After stirring, the mixture was allowed to stand for 30 minutes, and the lower aqueous layer was removed. Further, pure water (350.0 g) was added and the mixture was stirred for 30 minutes. After stirring, the mixture was allowed to stand for 30 minutes, and the lower aqueous layer was removed. The resulting solution was vacuum-dried at 90°C for 16 hours to obtain vinyl polymers (hereinafter also referred to as "modified polymers 8-11"). The molecular weight, average number of end groups, and degree of coloration of each modified polymer are shown in Table 1.

[0072]

[0073] The details of the compounds used in Table 1 are shown below. • AA: Acrylic acid • 4PA: 4-Pentenoic acid • GLA: Glycolic acid • OTA: o-Tolylacetic acid • TMG: Tetramethylguanidine (boiling point: 163°C) • DBU: 1,8-Diazabicyclo[5.4.0]-7-Undecene (boiling point: 261°C) • TPP: Triphenylphosphine (boiling point: 377°C) • TBAA: Tetrabutylammonium acrylate synthesized in Synthesis Example 2 • AK: Potassium acrylate

[0074] Furthermore, the polar component of the Hansen solubility parameter of each solvent used in the examples and comparative examples (hereinafter referred to as "δ") ｐ The δ of each solvent was calculated using the method described in the reference "C. M. Hansen "The three-dimensional solubility parameter." Danish Technical: Copenhagen 14 (1967)". ｐ This is shown in Table 1.

[0075] ≪Evaluation Results≫ As is clear from the results of Examples 1 to 12, by reacting vinyl polymers having terminal halogens with a quaternary ammonium salt of a carboxylic acid, or a neutralized product of a carboxylic acid and an organic base with a boiling point of 200°C or lower, vinyl polymers with high productivity, a high rate of terminal group introduction, and low coloration could be obtained. Among these, when a quaternary ammonium salt was used (Examples 8 to 10), a high rate of terminal group introduction into the vinyl polymer could be achieved with a shorter reaction time. Also, δ ｐ 1.0 (cal / cm) ０．５ In Examples 1 to 3 using the above solvents, δ ｐ 0.7 (cal / cm) ０．５ Compared to Example 4, which used a different solvent, a higher rate of terminal group introduction was achieved in a shorter reaction time.

[0076] In contrast, when a vinyl polymer having terminal halogens was reacted with a carboxylate salt containing an inorganic cation (Comparative Example 1), the rate of introduction of terminal groups into the vinyl polymer could not be sufficiently high with the same reaction time as in the Examples (3.0 hours), and furthermore, the degree of discoloration of the modified product was also high. In addition, when a neutralized product of a carboxylic acid and an organic base with a boiling point exceeding 200°C was used as a modifying agent (Comparative Examples 2 and 3), the degree of discoloration of the modified product was also high.

[0077] The present invention is not limited to the embodiments described above, and encompasses various modifications and variations within the scope of equivalents, without departing from the spirit of the invention. Therefore, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of these elements, should be understood to fall within the scope and conceptual range of the present invention in light of the above teachings.

Claims

1. A method for producing a vinyl polymer, comprising the steps of: obtaining a polymer (P) having halogen atoms at its molecular ends and containing structural units derived from vinyl monomers; and reacting the polymer (P) with a carboxylate salt having an organic cation, wherein the carboxylate salt is either a quaternary ammonium salt or a neutralized product of a carboxylic acid and an organic base having a boiling point of 200°C or less.

2. The method for producing a vinyl polymer according to claim 1, wherein the halogen atom is an iodine atom.

3. A method for producing a vinyl polymer according to claim 1 or 2, wherein the organic base has a nitrogen atom.

4. Polarity component δ in Hansen solubility parameters ｐ 1.0 (cal / cm) ０．５ A method for producing a vinyl polymer according to claim 1 or 2, comprising reacting the polymer (P) and the carboxylate in the solvent described above.

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