Method for manufacturing vinyl polymers

Abstract

This invention provides a highly versatile method for producing vinyl polymers, which allows for the efficient and simple removal of tellurium compounds from polymers synthesized by the TERP method, thereby obtaining vinyl polymers with a tellurium content reduced by 90% or more compared to those before purification. [Solution] A method for producing a vinyl polymer, comprising the steps of: (i) obtaining a polymer by living radical polymerization of a vinyl monomer using an organic tellurium compound; (ii) reacting the polymer with a reducing agent to obtain a first mixture containing an organic ditellium compound and a vinyl polymer; (iii) reacting the first mixture with an organic peroxide represented by general formula (1) to obtain a second mixture containing a vinyl polymer and a tellurium compound; and (iv) washing the second mixture with a solvent to remove the tellurium compound. TIFF2026144449000017.tif12170(X represents -CO- or -COO-, and R1 and R2 independently represent an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 20 carbon atoms)

Description

[Technical Field]

[0001] This invention relates to a method for producing vinyl polymers. [Background technology]

[0002] Living radical polymerization is a polymerization method that can produce polymers with precisely controlled molecular structures and polymers with uniform compositions, which was difficult to achieve with conventional radical polymerization methods. Various methods have been reported as living radical polymerization methods. Among them, the TERP (organotelurium-mediated living radical polymerization) method, which uses organotelurium compounds, is a polymerization method that has attracted particular attention due to its versatility in being applicable to the polymerization of various types of vinyl monomers, its simplicity in being able to polymerize under mild reaction conditions, and its precision in being able to highly control the molecular weight and molecular weight distribution of the polymer (Patent Documents 1-4).

[0003] The growth ends of polymers obtained by living radical polymerization are usually referred to as dormant ends, where the radicals are reversibly protected with appropriate protecting groups. In the TERP method, organotellurium functional groups are used as these protecting groups. However, organotellurium compounds have been noted to be biotoxic and environmentally polluting (Non-Patent Documents 1 and 2). Therefore, there is a need to develop a method for efficiently removing organotellurium compounds from polymers obtained by the TERP method.

[0004] For example, a method has been proposed in which a reducing agent is reacted with an organic tellurium functional group at the dormant terminus to form an organic ditellulose compound, and then the polymer and the organic ditellulose compound are separated by liquid-liquid extraction and washing (Patent Document 5). Another method has been proposed in which a polymer obtained by using an organic tellurium functional group with a fluorine-containing alkyl group introduced as a protecting group at the dormant terminus is reacted with an organic tellurol compound having a fluorine-containing alkyl group as a reducing agent, and then washed with a fluorine-based solvent (Patent Document 6).

[0005] Furthermore, a method has been proposed in which a polymer obtained by emulsion polymerization by the TERP method is treated with a reducing agent having hydrophilic functional groups to produce an organic tellurium compound into which hydrophilic functional groups have been introduced, and then subjected to solid-liquid separation (Patent Document 7). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2004 / 014848 [Patent Document 2] International Publication No. 2004 / 014962 [Patent Document 3] International Publication No. 2004 / 072126 [Patent Document 4] International Publication No. 2004 / 096870 [Patent Document 5] Japanese Patent Publication No. 2017-200961 [Patent Document 6] Japanese Patent Publication No. 2017-200882 [Patent Document 7] International Publication No. 2021 / 230253 [Non-patent literature]

[0007] [Non-Patent Document 1] Environ.Sci.Technol.,2017,51,5859-6610 [Non-Patent Document 2] EFSA Journal,2020,EU-FORA Series3,e181101 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present inventors verified the method proposed in Patent Document 5. As a result, it was found that the removal rate of organic ditellurium compounds only remains at 90% or lower. In addition, the method proposed in Patent Document 6 requires complicated synthesis steps and the use of organofluorine compounds, which raise concerns about biotoxicity and environmental pollution, so practical application is difficult.

[0009] Note that the method proposed in Patent Document 7 requires the use of a special reducing agent. For example, reducing agents such as aminoethanethiol and sodium borohydride cannot impart water solubility to tellurium compounds, so they cannot be applied to the method proposed in Patent Document 7. Further, even when thiophenols are used, it is difficult to obtain organic tellurium compounds introduced with hydrophilic functional groups in high yield. The only thiophenol recognized as usable in Patent Document 7 is 4-mercaptobenzoic acid. Since thiophenols introduced with various functional groups other than 4-mercaptobenzoic acid cannot be used, the method proposed in Patent Document 7 has a problem in versatility. Furthermore, obtaining a reducing agent having a hydrophilic functional group requires a complicated synthesis step, so there is a problem in versatility.

[0010] The present invention has been made in view of the above problems of the prior art. An object of the present invention is to provide a highly versatile method for producing a vinyl polymer, which enables highly efficient and simple removal of tellurium compounds from a polymer synthesized by the TERP method to obtain a vinyl polymer having a tellurium content reduced by 90% or more compared to that before purification. [Means for Solving the Problems]

[0011] That is, according to the present invention, the following method for producing a vinyl polymer is provided. [1] A process for producing a vinyl polymer, comprising: step (i) of obtaining a polymer by living radical polymerization of a vinyl monomer using an organic tellurium compound; step (ii) of obtaining a first mixture containing an organic ditellurium compound and a vinyl polymer by allowing at least one reducing agent selected from the group consisting of a thiol compound, a borohydride compound, an aluminum hydride compound, and an organic tellurol to act on the polymer; step (iii) of obtaining a second mixture containing the vinyl polymer and a tellurium compound by allowing an organic peroxide represented by the following general formula (1) to act on the first mixture; and step (iv) of removing the tellurium compound from the second mixture by washing the second mixture with a solvent.

[0012] TIFF2026144449000001.tif12170 (In the general formula (1), X represents -CO- or -COO-, and R1 and R2 each independently represent an alkyl group having 1 to 20 carbon atoms, an aryl group, or an aromatic heterocyclic group)

[0013] [2] The method for producing a vinyl polymer according to [1], wherein the solvent used in the step (iv) is a solvent that dissolves the tellurium compound in the second mixture but does not dissolve the vinyl polymer.

Effect of the Invention

[0014] According to the present invention, there can be provided a method for producing a vinyl polymer that is excellent in versatility, which can highly efficiently and simply remove a tellurium compound from a polymer synthesized by a TERP method, to obtain a vinyl polymer having a tellurium content reduced by 90% or more compared to that before purification.

Mode for Carrying Out the Invention

[0015] <Method for producing vinyl polymer and vinyl polymer> The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described below. One embodiment of the method for producing a vinyl polymer of the present invention is a method that can produce a vinyl polymer with a low tellurium content and high purity, comprising the following steps (i) to (iv). The details of the method for producing a vinyl polymer of this embodiment will be described below. Step (i): A step to obtain a polymer by living radical polymerization of a vinyl monomer using an organotellurium compound. Step (ii): A step of reacting a polymer with at least one reducing agent selected from the group consisting of thiol compounds, boron hydride compounds, aluminum hydride compounds, and organotellurol to obtain a first mixture containing an organoditellurol compound and a vinyl polymer. Step (iii): A step of reacting the first mixture with an organic peroxide represented by the following general formula (1) to obtain a second mixture containing a vinyl polymer and a tellurium compound. Step (iv): Wash the second mixture with a solvent to remove the tellurium compound from the second mixture.

[0016] TIFF2026144449000002.tif12170 (In the above general formula (1), X represents -CO- or -COO-, and R1 and R2 independently represent an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 20 carbon atoms)

[0017] (Step (i)) Step (i) is a polymerization step in which vinyl monomers are subjected to living radical polymerization using an organotellurium compound to obtain a polymer, i.e., a polymerization step using the TERP method. The TERP method is described, for example, in International Publications 2004 / 014848, 2004 / 014962, 2004 / 072126, and 2004 / 096870.

[0018] In step (i), specifically, a polymer is obtained by living radical polymerization of a vinyl monomer using one of the following methods (a) to (d). (a) Organic tellurium compounds represented by the following general formula (4) (b) A mixture containing an organotellurium compound represented by the following general formula (4) and an azo polymerization initiator. (c) A mixture containing an organotellurium compound represented by the following general formula (4) and an organoditellurium compound represented by the following general formula (2). (d) A mixture comprising an organotellurium compound represented by the following general formula (4), an azo polymerization initiator, and an organoditellurium compound represented by the following general formula (2).

[0019] TIFF2026144449000003.tif25170 (In the above general formula (4), R3 represents an alkyl group having 1 to 8 carbon atoms, an aryl group, or an aromatic heterocyclic group. R5 and R6 independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R7 represents an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amide group, an oxycarbonyl group, a cyano group, an allyl group, or a propargyl group.)

[0020] TIFF2026144449000004.tif12170 (In the above general formula (2), R3 represents an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 8 carbon atoms)

[0021] In general formulas (2) and (4), the C1-C8 alkyl group represented by R3 can be a linear or branched alkyl group such as a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, and octyl group; a cyclic alkyl group such as a cyclohexyl group; and the like. Among these, a linear or branched alkyl group having C1-C4 is preferred, and a methyl group or an ethyl group is even more preferred.

[0022] Examples of the aryl group represented by R3 in general formulas (2) and (4) include the phenyl group and the naphthyl group.

[0023] Examples of aromatic heterocyclic groups represented by R3 in general formulas (2) and (4) include pyridyl groups, furyl groups, and thienyl groups.

[0024] In general formula (4), examples of C1-C8 alkyl groups represented by R5 and R6 include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, and octyl groups; and cyclic alkyl groups such as cyclohexyl groups. Among these, linear or branched alkyl groups having C1-C4 are preferred, and methyl or ethyl groups are even more preferred.

[0025] In general formula (4), the C1-C8 alkyl group represented by R7 can be a linear or branched alkyl group such as a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, and octyl group; a cyclic alkyl group such as a cyclohexyl group; and the like. Among these, a linear or branched alkyl group having C1-C4 is preferred, and a methyl group or an ethyl group is even more preferred.

[0026] In general formula (4), the aryl group represented by R7 can be a phenyl group or a naphthyl group, among others. A phenyl group is preferred.

[0027] Examples of substituted aryl groups represented by R7 in general formula (4) include substituted phenyl groups and substituted naphthyl groups. Substituents include halogen atoms, hydroxyl groups, alkoxy groups, amino groups, nitro groups, cyano groups, and -COR groups. 71 A carbonyl-containing group represented by (R 71 Examples of substituents include alkyl groups, aryl groups, alkoxy groups, or allyloxy groups having 1 to 8 carbon atoms, sulfonyl groups, and trifluoromethyl groups. The number of substituents is preferably 1 or 2 per aryl group.

[0028] In general formula (4), examples of the aromatic heterocyclic group represented by R7 include a pyridyl group, a furyl group, and a thienyl group.

[0029] In general formula (4), the alkoxy group represented by R7 is preferably a group in which an alkyl group having 1 to 8 carbon atoms is bonded to an oxygen atom, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, and an octyloxy group.

[0030] In general formula (4), examples of the acyl group represented by R7 include an acetyl group, a propionyl group, and a benzoyl group.

[0031] In general formula (4), the amide group represented by R7 is -CONR 721 R 722 a group represented by (R 721 , R 722 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group), and the like.

[0032] In general formula (4), the oxycarbonyl group represented by R7 is -COOR 73 a group represented by (R 73 is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group), and examples thereof include a carboxy group, a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an n-butoxycarbonyl group, a sec-butoxycarbonyl group, a tert-butoxycarbonyl group, an n-pentoxycarbonyl group, and a phenoxycarbonyl group. Among these, a methoxycarbonyl group or an ethoxycarbonyl group is preferable.

[0033] In general formula (4), the allyl group represented by R7 is -CR 741 R 742 -CR 743 =CR 744 R 745 a group represented by (R741 , R 742 R is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R is independent of each other. 743 , R 744 , and R 745 Examples include the following: each is independently a hydrogen atom, a C1-C8 alkyl group, or an aryl group, and the substituents may be bonded together to form a cyclic structure.

[0034] In general formula (4), the propargyl group represented by R7 is -CR 751 R 752 -C≡CR 753 The group represented by (R 751 and R 752 R is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R is independent of each other. 753 Examples include hydrogen atoms, alkyl groups having 1 to 8 carbon atoms, aryl groups, or silyl groups.

[0035] Examples of organic tellurium compounds represented by general formula (4) include (methylteranylmethyl)benzene, (methylteranylmethyl)naphthalene, methyl-2-methyl-2-methylteranyl-propionate, ethyl-2-methyl-2-methylteranyl-propionate, ethyl-2-methyl-2-n-butylteranyl-propionate, (2-trimethylsiloxyethyl)-2-methyl-2-methylteranyl-propinate, (2-hydroxyethyl)-2-methyl-2-methylteranyl-propinate, and (3-trimethylsilylpropargyl)-2-methyl-2-methylteranyl-propinate.

[0036] Examples of organic ditellurium compounds represented by general formula (2) include dimethyl ditelluride, diethyl ditelluride, di-n-propyl ditelluride, diisopropyl ditelluride, dicyclopropyl ditelluride, di-n-butyl ditelluride, di-s-butyl ditelluride, di-t-butyl ditelluride, dicyclobutyl ditelluride, diphenyl ditelluride, bis-(p-methoxyphenyl) ditelluride, bis-(p-aminophenyl) ditelluride, bis-(p-nitrophenyl) ditelluride, bis-(p-cyanophenyl) ditelluride, bis-(p-sulfonylphenyl) ditelluride, dinaphthyl ditelluride, and dipyridyl ditelluride.

[0037] As an azo polymerization initiator, any azo polymerization initiator commonly used in radical polymerization can be used without particular restrictions. Examples of azo initiators include 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2-methylbutyronitrile) (AMBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (V65), 1,1'-azobis(cyclohexane-1-carbonnitrile) (V40), dimethyl-2,2'-azobisisobutyrate (MAIB), 4,4'-azobis(4-cyanovaleric acid) (ACVA), 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobis(2-methylbutylamide), and 2,2'-azobis(4- Examples include methoxy-2,4-dimethylvaleronitrile) (V70), 2,2'-azobis(2-methylamidinopropane) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(2,4,4-trimethylpentane), 2-cyano-2-propylazoformamide, 2,2'-azobis(N-butyl-2-methylpropionamide), and 2,2'-azobis(N-cyclohexyl-2-methylpropionamide).

[0038] As for vinyl monomers, any those capable of radical polymerization can be used without particular limitations. The vinyl polymer produced by the manufacturing method of this embodiment may be a copolymer obtained by copolymerizing multiple vinyl monomers. In this specification, "vinyl monomer" means a monomer having a radically polymerizable carbon-carbon double bond in its molecule. "(meth)acrylic" means "at least one of acrylic and methacrylic," "(meth)acrylic acid" means "at least one of acrylic acid and methacrylic acid," and "(meth)acrylate" means "at least one of acrylate and methacrylate."

[0039] Specific examples of vinyl monomers include the following: (meth)acrylates having aliphatic alkyl groups such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0040] (Meth)acrylates having an alicyclic alkyl group, such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, bornyl (meth)acrylate, and isobornyl (meth)acrylate.

[0041] (Meth)acrylates having aromatic ring groups, such as benzyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate.

[0042] (Meth)acrylates having hydroxyl groups, such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0043] (Meth)acrylates having polyethylene glycol structural units, such as diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate.

[0044] Aromatic vinyl monomers such as styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene, and 1-vinylnaphthalene.

[0045] Vinyl monomers having a carboxyl group, such as monomers obtained by reacting (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, and hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate with acid anhydrides such as maleic anhydride, succinic anhydride, or phthalic anhydride.

[0046] Vinyl monomers having a sulfonic acid group, such as styrene sulfonic acid, dimethylpropyl sulfonic acid (meth)acrylamide, ethyl sulfonate (meth)acrylate, ethyl sulfonate (meth)acrylamide, and vinyl sulfonic acid.

[0047] Vinyl monomers having a phosphate group, such as methacryloyloxyethyl phosphate ester.

[0048] (meth)acrylamides such as (meth)acrylamide, N-methyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N,N-dimethyl(meth)acrylamide.

[0049] Unsaturated monomers containing tertiary amines such as N,N-dimethylaminopropyl(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylamide, 2-(dimethylamino)ethyl(meth)acrylate, and N,N-dimethylaminopropyl(meth)acrylate.

[0050] Quaternary ammonium base-containing unsaturated monomers such as N-2-hydroxy-3-acryloyloxypropyl-N,N,N-trimethylammonium chloride and N-methacryloylaminoethyl-N,N,N-dimethylbenzylammonium chloride.

[0051] Epoxy group-containing unsaturated monomers such as glycidyl (meth)acrylate.

[0052] Heterocyclic unsaturated monomers such as 2-vinylthiophene, N-methyl-2-vinylpyrrole, 1-vinyl-2-pyrrolidone, 2-vinylpyridine, and 4-vinylpyridine.

[0053] Vinylamides such as N-vinylformamide, N-vinylacetamide, and N-vinyl-ε-caprolactam.

[0054] Vinyl carboxylates such as vinyl acetate, vinyl pivalate, and vinyl benzoate.

[0055] Alpha-olefins such as 1-hexene, 1-octene, and 1-decene.

[0056] Dienes such as butadiene, isoprene, 4-methyl-1,4-hexadiene, and 7-methyl-1,6-octadiene.

[0057] Among these, preferred vinyl monomers are (meth)acrylates having an aliphatic alkyl group, (meth)acrylates having an alicyclic alkyl group, (meth)acrylates having a hydroxyl group, aromatic vinyl monomers, (meth)acrylamides, tertiary amine-containing unsaturated monomers, heterocyclic-containing unsaturated monomers, and vinylamide monomers.

[0058] In step (i), the vinyl monomer and the organic tellurium compound are mixed in a container preferably purged with an inert gas, along with an azo polymerization initiator and an organic ditellurium compound represented by general formula (2), which are used as needed for purposes such as reaction acceleration and molecular weight control, depending on the type of vinyl monomer. Examples of inert gases include nitrogen, argon, and helium. Among these, argon and nitrogen are preferred, and nitrogen is more preferred.

[0059] The amount of vinyl monomer used can be adjusted as appropriate depending on the desired properties of the vinyl polymer. Typically, 5 to 10,000 moles of vinyl monomer can be used per mole of organic tellurium compound.

[0060] When using an organic tellurium compound represented by general formula (4) in combination with an azo polymerization initiator, the amount of azo polymerization initiator used can usually be 0.01 to 10 moles per mole of the organic tellurium compound represented by general formula (4).

[0061] When using an organic tellurium compound represented by general formula (4) and an organic ditellulium compound represented by general formula (2) in combination, the amount of organic ditellulium compound represented by general formula (2) used can usually be 0.01 to 100 moles per mole of the organic tellurium compound represented by general formula (4).

[0062] When using an organic tellurium compound represented by general formula (4), an organic ditellulium compound represented by general formula (2), and an azo polymerization initiator in combination, the amount of azo polymerization initiator used can usually be 0.01 to 100 mol per 1 mol total of the organic tellurium compound represented by general formula (4) and the organic ditellulium compound represented by general formula (2).

[0063] Step (i) can be carried out without a solvent. However, it may also be carried out with stirring in the presence of a solvent commonly used in radical polymerization (aprotic solvent or protic solvent).

[0064] Examples of aprotic solvents include benzene, toluene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, 2-butanone (methyl ethyl ketone), dioxane, hexafluoroisopropaol, chloroform, dichloromethane, carbon tetrachloride, tetrahydrofuran (THF), ethyl acetate, propyl acetate, butyl acetate, trifluoromethylbenzene, propylene glycol monomethyl ether acetate, and methylcyclohexane.

[0065] Examples of protic solvents include water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol, 1-propoxy-2-propanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diacetone alcohol.

[0066] The amount of solvent used can be adjusted as appropriate. For example, the amount of solvent used is usually 0.01 to 50 mL per 1 g of vinyl monomer, preferably 0.05 to 10 mL, and more preferably 0.1 to 1 mL.

[0067] The reaction temperature and reaction time should be adjusted as appropriate according to the molecular weight and molecular weight distribution of the target vinyl polymer. The reaction temperature is typically 0 to 150°C, and the reaction time is typically 1 minute to 100 hours.

[0068] The growth ends of the polymer formed in step (i) are bonded to functional groups containing tellurium (Te) derived from the organic tellurium compound. For example, when an organic tellurium compound represented by general formula (4) is used, a "-TeR3" group (hereinafter also referred to as the "tellurium group" for convenience) derived from the organic tellurium compound represented by general formula (4) is bonded. Therefore, the polymer formed in step (i) can be used as a macro-living radical polymerization initiator. That is, by using the polymer formed in step (i) as a macro-living radical polymerization initiator, AB block copolymers, ABA triblock copolymers, and ABC triblock copolymers can be produced.

[0069] (Step (ii)) In step (ii), a reducing agent is applied to the polymer obtained in step (i). The reducing agent acts on the tellurium groups present at the growth ends of the polymer. As a result, the tellurium groups are removed from the growth ends of the polymer, and an organic ditellurium compound is generated, yielding a first mixture containing the organic ditellurium compound and the vinyl polymer.

[0070] The resulting organic ditellurium compound has a structure represented by, for example, the following general formula (2). The formation of an organic ditellurium compound represented by general formula (2), etc., can be confirmed by analysis, for example, proton nuclear magnetic resonance spectroscopy (NMR) or gas chromatography-mass spectrometry.

[0071] TIFF2026144449000005.tif12170 (In the above general formula (2), R3 represents an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 8 carbon atoms)

[0072] The polymer isolated from the polymer (polymerization solution containing the polymer) obtained in step (i) may be dissolved in a solvent before being treated with a reducing agent, or the reducing agent may be added to the polymer obtained in step (i) and then treated. From the viewpoint of shortening the process, it is preferable to add the reducing agent to the polymer (polymerization solution) obtained in step (i) and then treat it.

[0073] As a reducing agent, at least one selected from the group consisting of thiol compounds, boron hydride compounds, aluminum hydride compounds, and organic tellurols is used. These reducing agents are compounds that exhibit reducing properties towards tellurium groups present at the growth ends of polymers.

[0074] Examples of thiol compounds include thiophenol, p-aminothiophenol, m-aminothiophenol, o-aminothiophenol, p-hydroxythiophenol, m-hydroxythiophenol, o-hydroxythiophenol, p-mercaptobenzoic acid, m-mercaptobenzoic acid, o-mercaptobenzoic acid, 2-aminoethanethiol, 1-thioglycerol, 1-heptanethiol, 1-dodecanethiol, 3-mercaptopropionic acid, thioglycolic acid, and 2-mercaptoethanol. Among these, thiophenol, p-aminothiophenol, o-aminothiophenol, and 2-aminoethanethiol are preferred.

[0075] Examples of boron hydride compounds include borane complexes (borane-dimethyl sphide complex, borane-tetrahydrofuran complex, etc.), diborane, lithium borohydride, sodium borohydride, potassium borohydride, calcium borohydride, sodium triacetoxyborohydride, sodium cyanoborohydride, lithium tri(sec-butyl)borohydride, potassium tri(sec-butyl)borohydride, lithium triethylborohydride, zinc borohydride, tetramethylammonium borohydride, tetraethylammonium borohydride, tetrabutylammonium borohydride, trimethyloctylammonium borohydride, and trimethylbenzylammonium borohydride. Among these, sodium borohydride and lithium triethylborohydride are preferred from the viewpoints of safety, economy, and ease of handling.

[0076] Examples of aluminum hydride compounds include lithium aluminum hydride and sodium bis(2-methoxyethoxy)aluminum hydride.

[0077] Examples of organotelrol compounds include those represented by the following general formula (5).

[0078] TIFF2026144449000006.tif12170 (In the above general formula (5), R3 represents an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 8 carbon atoms)

[0079] In general formula (5), R3 is the same as R3 in general formulas (2) and (4) mentioned above. Examples of organotelrol compounds represented by general formula (5) include methyltelrol, ethyltelrol, n-propyltelrol, isopropyltelrol, n-butyltelrol, s-butyltelrol, t-butyltelrol, phenyltelrol, p-methoxyphenyltelrol, p-aminophenyltelrol, p-nitrophenyltelrol, p-cyanophenyltelrol, p-sulfonylphenyltelrol, and naphthyltelrol, pyridyltelrol, and the like.

[0080] In step (ii), for example, a reducing agent is added to the polymer (polymerization solution) obtained in step (i) and stirred. The reaction time can be set appropriately according to the reaction temperature, and is usually 5 minutes to 24 hours, preferably 10 minutes to 3 hours. The reaction temperature is usually 0 to 100°C, preferably room temperature (25°C) to 70°C.

[0081] The amount of solvent used can be adjusted as appropriate. For example, the amount of solvent used is usually 0.01 to 100 mL per 1 g of polymer, preferably 0.1 to 10 mL.

[0082] The amount of reducing agent used is typically 1.0 to 5.0 moles, preferably 1.0 to 3.0 moles, per 1.0 mole of the organic tellurium compound.

[0083] The reducing agent may be used in the form of a solution dissolved in a solvent. Any solvent capable of dissolving the reducing agent can be used. Examples of solvents include methanol, dimethylformamide (DMF), tetrahydrofuran (THF), toluene, xylene, hexane, dimethoxyethane, methyl ethyl ketone, and propylene glycol monomethyl ether acetate.

[0084] (Step (iii)) In step (iii), the first mixture obtained in step (ii) is reacted with an organic peroxide represented by the following general formula (1) to obtain a second mixture containing a vinyl polymer and a tellurium compound. By reacting with the organic peroxide represented by the following general formula (1), the organic ditellurium compound in the first mixture is oxidized to produce a tellurium compound that has affinity for the washing solvent.

[0085] TIFF2026144449000007.tif12170 (In the above general formula (1), X represents -CO- or -COO-, and R1 and R2 independently represent an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 20 carbon atoms.)

[0086] Tellurium compounds produced by the oxidation of organic ditellurium compounds have a structure represented by, for example, the following general formula (3). The formation of tellurium compounds represented by general formula (3), etc., can be confirmed by analysis, for example, NMR, gas chromatography-mass spectrometry, or liquid chromatography-mass spectrometry.

[0087] TIFF2026144449000008.tif12170 (In the above general formula (3), Y represents -CO-, -COO-, -OCO-, or -OCOO-, R3 is equivalent to R3 in the above general formula (2), and R4 represents the same group as R1 or R2 in the above general formula (2))

[0088] In general formula (1), the C1-C20 alkyl groups represented by R1 and R2 include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, tert-hexyl, 2-ethylhexyl, heptyl, octyl, lauryl, and dodecyl groups; and cyclic alkyl groups such as cyclohexyl groups. Among these, linear or branched alkyl groups having 10-C20 carbon atoms are preferred, and lauryl groups are even more preferred.

[0089] Examples of aryl groups represented by R1 and R2 in general formula (1) include phenyl groups, naphthyl groups, and cumyl groups.

[0090] Examples of aromatic heterocyclic groups represented by R1 and R2 in general formula (1) include pyridyl groups, furyl groups, and thienyl groups.

[0091] C1-C20 alkyl groups, aryl groups, and aromatic heterocyclic groups may have substituents. Examples of substituents include carboxyl groups, hydroxyl groups, amide groups, and amino groups.

[0092] Examples of substituted alkyl groups include carboxyethyl group, 3-carboxypropyl group, hydroxyethyl group, and aminoethyl group. Among these, the 3-carboxypropyl group is preferred.

[0093] Examples of substituted aryl groups include carboxyphenyl groups, hydroxyphenyl groups, and aminophenyl groups.

[0094] Examples of substituted aromatic heterocyclic groups include hydroxypyridyl groups, aminoethylpyridyl groups, aminoethylthienyl groups, and carboxythienyl groups.

[0095] It has been reported that when diphenyl diterlide, a type of organic ditellurium compound, is treated with benzoyl peroxide, the reaction represented by formula (6) below proceeds, producing benzeneterrenyl benzoates, a type of compound represented by general formula (3) (Journal of the Chemical Society of Japan, 1987, 7, 1479-1484).

[0096] TIFF2026144449000009.tif39170

[0097] Based on the above report, the present inventors hypothesized that (i) reacting an organic peroxide having a highly hydrophilic functional group with an organic ditellurium compound produces a highly hydrophilic tellurium compound that can be efficiently washed and removed in a highly polar solvent; and (ii) reacting an organic peroxide having a highly hydrophobic functional group with an organic ditellurium compound produces a highly hydrophobic tellurium compound that can be efficiently washed and removed in a low-polarity solvent. Based on these hypothesis, the inventors further investigated and arrived at the present invention.

[0098] As the organic peroxide, at least one selected from the group consisting of peroxyesters, diacyl peroxides, and peroxydicarbonates can be used. Examples of organic peroxides include benzoyl peroxide, lauroyl peroxide, di-2-ethylhexyl peroxydicarbonate, (2-ethylhexanoyl)(tert-butyl) peroxide, bis(3,5,5-trimethylhexanoyl) peroxide, dicumyl peroxide, and bis(3-carboxypropionyl) peroxide. When producing a highly hydrophobic vinyl polymer, it is preferable to use bis(3-carboxypropionyl) peroxide having a hydrophilic functional group as the organic peroxide in order to generate a highly hydrophilic tellurium compound represented by general formula (3), etc. On the other hand, when producing a highly hydrophilic vinyl polymer, it is preferable to use lauroyl peroxide having a hydrophobic functional group as the organic peroxide in order to generate a highly hydrophobic tellurium compound represented by general formula (3), etc.

[0099] Organic peroxides represented by general formula (1) may be used in the form of a solution dissolved in a solvent. Any solvent capable of dissolving organic peroxides can be used. Examples of solvents include methanol, dimethylformamide (DMF), tetrahydrofuran (THF), toluene, xylene, hexane, dimethoxyethane, methyl ethyl ketone, and propylene glycol monomethyl ether acetate. When using highly hydrophilic organic peroxides such as bis(3-carboxypropionyl) peroxide, methanol and DMF are preferred. On the other hand, when using highly hydrophobic organic peroxides such as lauroyl peroxide, DMF, THF, methyl ethyl ketone, toluene, and propylene glycol monomethyl ether acetate are preferred. The amount of solvent used is usually 1 to 100 mL, preferably 1 to 10 mL, per 1 g of organic peroxide.

[0100] In step (iii), for example, the organic peroxide solution is added dropwise to the first mixture (solution) obtained in step (ii) and stirred. The reaction time can be set according to the reaction temperature, and is usually 5 minutes to 24 hours, preferably 10 minutes to 3 hours. The reaction temperature is usually 0 to 100°C, preferably 60 to 100°C.

[0101] The amount of solvent used can be adjusted as appropriate. For example, the amount of solvent used is usually 0.01 to 100 mL per 1 g of polymer, preferably 0.1 to 10 mL.

[0102] The organic peroxide reacts not only with the organic ditellurium compound represented by general formula (2) but also with the reducing agent used in step (ii). Therefore, the amount of organic peroxide used should be appropriately adjusted according to the sum of the amount of the organic ditellurium compound represented by general formula (2) and the amount of the reducing agent used in step (ii). Specifically, it is preferable to use 1.0 to 5.0 mol of organic peroxide per 1.0 mol of the organic ditellurium compound represented by general formula (2) in the first mixture, plus 1.0 to 5.0 mol per 1.0 mol of the reducing agent used in step (ii). Furthermore, it is even more preferable to use 1.0 to 3.0 mol of organic peroxide per 1.0 mol of the organic ditellurium compound represented by general formula (2) in the first mixture, plus 1.0 to 3.0 mol per 1.0 mol of the reducing agent used in step (ii).

[0103] (Step (iv)) In step (iv), the second mixture obtained in step (iii) is washed with a solvent to remove the tellurium compound from the second mixture. This allows the desired vinyl polymer to be obtained. The second mixture can be washed according to known washing methods. For example, it is preferable to combine precipitation of the vinyl polymer with a poor solvent and filtration washing. Alternatively, a solution obtained by dissolving the vinyl polymer isolated from the second mixture (solution) after step (iii) in a suitable solvent may be used, or the second mixture (solution) after step (iii) may be used.

[0104] While stirring the washing solvent (washing solvent) with a homomixer, a second mixture (solution) containing the tellurium compound and vinyl polymer is slowly added dropwise. This dissolves the tellurium compound in the washing solvent and precipitates the vinyl polymer. The tellurium compound can then be separated by filtration, and the precipitated vinyl compound can be recovered. Furthermore, by redissolving the recovered vinyl polymer in a suitable solvent and repeating the above washing operation, an even higher purity vinyl polymer with a further reduced tellurium (Te) content can be obtained.

[0105] As the washing solvent, it is preferable to use a solvent that is easily miscible with the solvent that dissolves the vinyl polymer. Furthermore, as the washing solvent, it is preferable to use a solvent that dissolves the tellurium compound but does not dissolve the vinyl polymer. Examples of washing solvents include water, methanol, ethanol, ethyl acetate, and hexane. In step (iii), if a highly hydrophilic tellurium compound is produced using an organic peroxide having a hydrophilic group such as bis(3-carboxypropionyl) peroxide, it is preferable to use water and methanol as the washing solvent. On the other hand, in step (iii), if a highly hydrophobic tellurium compound is produced using an organic peroxide having a hydrophobic group such as lauroyl peroxide, it is preferable to use ethyl acetate and hexane as the washing solvent.

[0106] The washing solvent may contain an acid or an alkali. If an organic peroxide having a basic substituent is used in step (iii), the efficiency of removing the tellurium compound can be improved by using a washing solvent containing an acid. On the other hand, if an organic peroxide having an acidic substituent is used in step (iii), the efficiency of removing the tellurium compound can be improved by using a washing solvent containing an alkali. Examples of acids include acetic acid, hydrochloric acid, and sulfuric acid. Examples of alkalis include sodium hydroxide, potassium hydroxide, lithium hydroxide, and ammonia.

[0107] The amount of washing solvent used can be adjusted as appropriate. Typically, 1 to 200 mL of washing solvent is used per 1 mL of the vinyl polymer solution, preferably 5 to 50 mL. The washing operation is usually carried out at 10 to 70°C, preferably at room temperature (25°C) to 60°C.

[0108] (Vinyl polymer) The molecular weight of the vinyl polymer produced by the manufacturing method of this embodiment can be appropriately adjusted by the reaction time in step (i) and the amount of organotellurium compound used. Specifically, a vinyl polymer with a number average molecular weight (Mn) of 500 to 1,000,000, preferably 1,000 to 50,000, can be obtained. The number average molecular weight (Mn) of the vinyl polymer can be measured by gel permeation chromatography (GPC).

[0109] According to the manufacturing method of this embodiment, a vinyl polymer with a molecular weight distribution (PDI = weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of 1.5 or less can be obtained. Furthermore, the tellurium (Te) content of the vinyl polymer produced by the manufacturing method of this embodiment, as measured by inductively coupled plasma (ICP) emission spectroscopy, is usually 1,000 ppm or less, preferably 500 ppm or less, and more preferably 100 ppm or less.

[0110] The vinyl polymer produced by the manufacturing method of this embodiment has a low tellurium (Te) content and can therefore be suitably used in applications such as optical, medical, electrical and electronic, and energy materials. [Examples]

[0111] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0112] <Manufacturing of vinyl polymers> (Preparation of each component (material)) The following components (materials) were prepared.

[0113] [Organotellurium compounds] MMMTP: Methyl-2-methyl-2-methylteranyl propionate

[0114] [Azo polymerization initiators] AIBN: 2,2'-Azobis(isobutyronitrile) · V40: 1,1'-Azobis(cyclohexane-1-carbonitride)

[0115] [Vinyl monomer] IBXA: Isobornyl acrylate • 4VP: 4-vinylpyridine

[0116] [Polymerization solvent] DMF: Dimethylformamide

[0117] [Reducing agent] • APhSH: p-aminothiophenol NaBH4: Sodium borohydride

[0118] [Organic peroxide] • PSA: Bis(3-carboxypropionyl)peroxide (trade name "Perloyl SA", manufactured by NOF Corporation) • LPO: Lauroyl peroxide (product name "Perloyl L", manufactured by NOF Corporation)

[0119] (Outline of each process) [Process (i)] The types of organotellurium compounds, azo polymerization initiators, vinyl monomers, and polymerization solvents shown in Tables 1 and 4 were used, and the vinyl monomers were subjected to living radical polymerization according to the polymerization conditions shown in Tables 1 and 4. In Tables 1, 2, 4, and 5, the "equivalent" of each component refers to the "molar equivalent" based on the organotellurium compound.

[0120] [Step (ii)] The solution obtained after polymerization in step (i) was treated by adding the types and equivalent amounts of reducing agents shown in Tables 2 and 5, and then processing according to the treatment conditions shown in Tables 2 and 5.

[0121] [Step (iii)] The solution obtained after processing in step (ii) was treated with the types and equivalent amounts of organic peroxides shown in Tables 2 and 5, and the mixture (second mixture) was obtained by processing according to the treatment conditions shown in Tables 2 and 5.

[0122] [Step (iv)] The mixture obtained in step (iii) was washed using the types of washing solvents shown in Tables 2 and 5. The washing cycle shown in Tables 2 and 5 was repeated to obtain the target polymer. When washing the filtered polymer again, the polymer was redissolved using the same polymerization solvent used in step (i). Details of the obtained polymer are shown in Tables 3 and 6. The polymer recovery rate (%) is the mass ratio of the polymer based on the amount of vinyl monomer used. The tellurium (Te) content (ppm) is the content of tellurium (Te) in the obtained polymer. The tellurium (Te) removal rate (%) is the ratio of the removed tellurium compound based on the total amount of tellurium compound used throughout the entire process.

[0123] (Measurement methods for various physical properties, etc.) [Number-average molecular weight (Mn) and molecular weight distribution (PDI) of polymers] The number-average molecular weight (Mn) of the polymer was measured using GPC, and the molecular weight distribution (PDI) was calculated. The GPC conditions are shown below.

[0124] [Example 1, Comparative Examples 1-3] • Eluent: Tetrahydrofuran (THF) • GPC: Product name "Shodex GPC-104" (manufactured by Resonaq, column: Shodex LF-404, 2 pieces) • Standard material: Polystyrene standard sample (product name "Shodex Standard M-75", manufactured by Resonaq Corporation)

[0125] [Example 2, Comparative Examples 4-6] • Eluent: DMF (10mM lithium bromide solution) • GPC: Product name "Agilent 1260 InfinityII" (manufactured by Agilent Technologies, column: Agilent Polargel-M 300×75mm, 2 tubes) • Reference material: Polymethyl methacrylate standard sample (product name "Agilent MM-10", manufactured by Agilent Technologies)

[0126] [Tellurium (Te) content and removal rate] 0.5 g of precisely weighed polymer was added to nitric acid-hydrochloric acid, decomposed by microwave heating, and then diluted with ultrapure water. Further dilution with 1% hydrochloric acid aqueous solution was performed to prepare the sample for analysis. The prepared sample was analyzed using an inductively coupled plasma atomic emission spectrometer (ICP-OES, trade name "Agilent 5110", manufactured by Agilent Technologies) to measure and calculate the tellurium (Te) content (ppm) and removal rate (%). Tellurium standard solution (trade name "Te1000", manufactured by Kanto Chemical Co., Ltd.) was used as the standard substance. Each sample was measured twice and the average value was calculated.

[0127] [Proton Nuclear Magnetic Resonance Spectroscopy (NMR Spectroscopy)] Using NMR spectroscopy, the formation of the organic diterlide compound in step (ii) and its disappearance in step (iii) were observed, confirming the completion of the reaction in each step. The conditions for the NMR spectroscopy are shown below. ·FT-NMR device: Product name “NMR spectrometer ECZ Luminous JNM-ECZL S series” (manufactured by JASCO Corporation, 400MHz)

[0128] [Example 1, Comparative Examples 1-3] • Deuterated solvent: Chloroform-d1, containing 0.05% tetramethylsilane (CDCl3) The analysis was performed using the tetramethylsilane peak (0.00 ppm) as the reference point.

[0129] [Example 2, Comparative Examples 4-6] • Deuterated solvent: Dimethyl sulfoxide-d6 (DMSO-d6) The analysis was performed using the dimethyl sulfoxide peak (2.50 ppm) as the reference point.

[0130] (Example 1) [Process (i)] 43.0 μL (0.25 mmol) of MMMTP, 10.4 g (50 mmol, 200 equivalents) of IBXA, 41.1 mg (0.25 mmol, 1.0 equivalent) of AIBN, and 5.6 g of toluene were placed in a Schlenk tube. The mixture was stirred at 60°C for 4 hours under a nitrogen atmosphere to obtain a polymer (polyisobornyl methacrylate) with organotellurium groups bonded to the ends. The Mn of the polymer, measured by GPC, was 21,500, and the PDI (=Mw / Mn) was 1.19. The monomer conversion rate, calculated from the residue after heating at 180°C, was 100%. The theoretical tellurium (Te) content per polymer solid at this stage was 3,000 ppm.

[0131] [Step (ii)] A solution prepared by dissolving 62.6 mg (0.50 mmol, 2.0 equivalents) of APhSH in 4.85 g of toluene was added to the obtained polymer. The mixture was stirred at 60°C for 2 hours to obtain a solution (first mixture) containing the organic ditellurium compound and the polymer. The sampled first mixture was dissolved in CDCl3 and analyzed by NMR. The presence of a peak originating from Te-CH3 at 2.66 ppm confirmed the formation of dimethyl diterlide, an organic ditellurium compound.

[0132] [Step (iii)] To the obtained solution, a solution prepared by dissolving 0.293 g (1.25 mmol, 5.0 equivalents) of PSA in 2.6 g of DMF, and 7.9 g of toluene were added. The mixture was stirred at 90°C for 2 hours to obtain a solution (second mixture) containing the tellurium compound and polymer. The sampled second mixture was dissolved in CDCl3 and analyzed by NMR. The disappearance of the peak originating from 2.66 ppm Te-CH3 confirmed that the dimethyl diterlide was consumed by the organic peroxide.

[0133] [Step (iv)] A mixture of 225 g of methanol and 25 g of 5% sodium hydroxide aqueous solution was stirred using a homomixer, and the resulting solution was added dropwise. After stirring for 10 minutes, the precipitate was filtered using a Buchner funnel and washed with 200 g of methanol to recover the polymer. The recovered polymer was dissolved in 30 mL of toluene, and the same precipitation and filtration procedure was repeated a total of three times. The Mn of the polymer measured by GPC was 21,000, and the PDI (=Mw / Mn) was 1.20. The polymer recovery rate calculated from the measured mass was 95%. The tellurium (Te) content of the polymer measured and calculated by ICP analysis was 61 ppm, and the tellurium (Te) removal rate was 98.0%.

[0134] (Comparative Examples 1-3) The polymer was obtained in the same manner as in Example 1 described above, except that steps (ii) to (iv) were carried out under the conditions shown in Table 2. The physical properties of the obtained polymer are shown in Table 3.

[0135] TIFF2026144449000010.tif62170

[0136] TIFF2026144449000011.tif61170

[0137] TIFF2026144449000012.tif47170

[0138] As shown in Table 3, the removal rate of tellurium (Te) in Comparative Examples 1-3 was 90% or less, while in Example 1, the removal rate was as high as 98.0%. In Example 1, dimethyl diterlide reacted with PSA to convert it into a tellurium compound with a carboxyl group introduced, which improved its polarity and alkali solubility, as well as its affinity for the washing solvent, thus leading to a higher removal rate.

[0139] (Example 2) [Process (i)] 137 μL (0.80 mmol) of MMMTP, 8.4 g (80 mmol, 100 equivalents) of 4VP, 195 mg (0.80 mmol, 1.0 equivalent) of V40, and 8.4 g of DMF were placed in a Schlenk tube. The mixture was stirred at 85°C for 4 hours under a nitrogen atmosphere to obtain a polymer (poly-4-vinylpyridine) with organotellurium groups bonded to the ends. The Mn of the polymer, measured by GPC, was 9,400, and the PDI (=Mw / Mn) was 1.25. The monomer conversion rate calculated from the residue after heating at 180°C was 98%. The theoretical tellurium (Te) content per polymer solid at this stage was 11,400 ppm.

[0140] [Step (ii)] A solution prepared by dissolving 200 mg (1.60 mmol, 2.0 equivalents) of APhSH in 1.0 g of DMF was added to the obtained polymer. The mixture was stirred at 60°C for 2 hours to obtain a solution (first mixture) containing the organic ditellurium compound and the polymer. The sampled first mixture was dissolved in DMSO-d6 and analyzed by proton NMR. The presence of a peak originating from Te-CH3 at 2.66 ppm confirmed that the generated organic ditellurium compound was dimethyl diterlide.

[0141] [Step (iii)] To the obtained solution, a solution prepared by dissolving 1.59 g (4.0 mmol, 5.0 equivalents) of LPO in 5.9 g of DMF was added. The mixture was stirred at 90°C for 2 hours to obtain a solution (second mixture) containing the tellurium compound and polymer. The sampled second mixture was dissolved in DMSO-d6 and analyzed by NMR. The disappearance of the peak originating from 2.66 ppm Te-CH3 confirmed that the dimethyl diterlide was consumed by the organic peroxide.

[0142] [Step (iv)] The resulting solution was added dropwise to 250 g of ethyl acetate while stirring with a homomixer. After stirring for 10 minutes, the precipitate was filtered using a Buchner funnel and washed with 200 g of ethyl acetate to recover the polymer. The recovered polymer was dissolved in 30 mL of DMF, and the same precipitation and filtration procedure was repeated a total of two times. The Mn of the polymer measured by GPC was 9,500, and the PDI (=Mw / Mn) was 1.29. The polymer recovery rate calculated from the measured mass was 90%. The tellurium (Te) content of the polymer measured and calculated by ICP analysis was 308 ppm, and the tellurium (Te) removal rate was 97.3%.

[0143] (Comparative Examples 4-6) The polymer was obtained in the same manner as in Example 2 described above, except that steps (ii) to (iv) were carried out under the conditions shown in Table 5. The physical properties of the obtained polymer are shown in Table 6.

[0144] TIFF2026144449000013.tif60170

[0145] TIFF2026144449000014.tif54170

[0146] TIFF2026144449000015.tif47170

[0147] As shown in Table 6, the removal rate of tellurium (Te) in Comparative Examples 4-6 was 90% or less, while in Example 2, the removal rate was as high as 97.3%. In Example 2, it is thought that the removal rate increased because dimethyl diterlide reacted with LPO to convert it into a tellurium compound with a lauryl group introduced, which reduced its polarity and increased its affinity for the washing solvent. [Industrial applicability]

[0148] The present invention's method for producing vinyl polymers is useful as a method for producing high-purity vinyl polymers with low tellurium content, suitable for applications such as optical, medical, electrical and electronic, and energy material applications.

Claims

1. (i) A step of obtaining a polymer by living radical polymerization of a vinyl monomer using an organotellurium compound, (ii) A step of reacting the polymer with at least one reducing agent selected from the group consisting of thiol compounds, boron hydride compounds, aluminum hydride compounds, and organotellurol to obtain a first mixture containing an organoditellurol compound and a vinyl polymer, Step (iii) of reacting the first mixture with an organic peroxide represented by the following general formula (1) to obtain a second mixture containing the vinyl polymer and the tellurium compound, A method for producing a vinyl polymer, comprising the step (iv) washing the second mixture with a solvent to remove the tellurium compound from the second mixture. (In the above general formula (1), X represents -CO- or -COO-, R １ and R ２ (Each of these independently represents an alkyl group, aryl group, or aromatic heterocyclic group having 1 to 20 carbon atoms.)

2. The method for producing a vinyl polymer according to claim 1, wherein the solvent used in step (iv) dissolves the tellurium compound in the second mixture but does not dissolve the vinyl polymer.

Images