Method for producing polymer particles, method for obtaining a mixed liquid containing polymer particles and an organotellurium compound, method for recovering tellurium, and dispersion of polymer particles

Abstract

The polymer particle production method according to the present invention comprises: (i) a step for causing a dispersion A5 of polymer particles A3, containing the polymer particles A3 formed from a polymer which is synthesized through emulsion polymerization using a first organotellurium compound as a polymerization control agent and in which a structure including an organotellurium group 1 at a growth terminal is controlled and containing a first solvent 4 in which the polymer particles A3 are to be dispersed, to be mixed with a reactant soluble to the first solvent 4, and removing the organotellurium group 1 from the growth terminal of the polymer, to obtain a liquid mixture 8 containing a second organotellurium compound 6 generated from a reaction between the reactant and the organotellurium group 1 and containing polymer particles B7 having less of the organotellurium group 1 than that in the polymer particles A3; and (ii) a step for separating the liquid mixture 8 into the polymer particles B7 and a solution 9 in which the second organotellurium compound 1 is dissolved.

Description

[Technical Field]

[0001] The present invention relates to a method for producing polymer particles composed of a polymer with a controlled structure, a method for obtaining a mixed liquid containing polymer particles and an organotellurium compound, a method for recovering tellurium, and a dispersion of polymer particles. [Background technology]

[0002] Living radical polymerization, also known as reversible deactivation radical polymerization, is an excellent polymerization method that combines the versatility of radical polymerization with the controllability of the molecular weight and molecular weight distribution of the synthesized polymer. Therefore, living radical polymerization has attracted considerable attention in recent years, and various living radical polymerization methods have been proposed. TERP (organotellurium-mediated living radical polymerization), a living radical polymerization method that uses organotellurium compounds as polymerization control agents, is particularly useful among living radical polymerization methods because of its versatility, being applicable to a variety of monomers, and its ability to precisely control the molecular weight and molecular weight distribution of the polymer.

[0003] Emulsion polymerization is a widely used method in conventional radical polymerization to easily obtain polymer particles with controlled particle size. The resulting polymer particles and dispersions of polymer particles are useful as polymer materials in many fields. However, controlling the structure of the polymer chains that make up the polymer particles has been difficult. In recent years, a very useful method has been proposed that extends the TERP method to emulsion polymerization in water, i.e., heterogeneous synthesis, which allows for precise control of the molecular weight and molecular weight distribution of the synthesized polymer as well as the particle size of the synthesized polymer particles (Non-Patent Documents 1 and 2).

[0004] Polymers synthesized by the TERP method have organotellurium groups attached to their growing ends. However, due to potential concerns about the toxicity of tellurium compounds, an effective method for removing and isolating the organotellurium groups from the polymer is needed. Furthermore, tellurium is a rare element, and its utility as a material for solar cells has recently increased. Therefore, it is desirable to not only separate and remove the organotellurium groups from the polymer, but also to recover them.

[0005] For polymers synthesized in a homogeneous solution by the TERP method, methods have been proposed for removing organotellurium groups attached to the growing ends of the polymers (Patent Documents 1 and 2). In this method, an organotellurol compound is used as a reducing agent to reduce the synthesized polymer, and the resulting ditelluride compound is separated by liquid-liquid extraction to remove the organotellurium groups from the polymer. Another proposed method utilizes solid-liquid extraction, in which the organotellurium groups are cleaved from the polymer using a thiol or the like, and the polymer is coagulated by adding a solvent with low affinity for the polymer, followed by separation and recovery of the organotellurium groups (Non-Patent Document 3). However, it is not possible to produce polymer particles with controlled particle size, as can be obtained by emulsion polymerization, from the polymers isolated by these methods. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-200882 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-200961 [Non-patent literature]

[0007] [Non-Patent Document 1] Fan, W., Tosaka, M., Yamago, S., Cunnigham, MF “Living ab initio Emulsion Polymerization of Methyl Methacrylate in Water Using a Water Soluble Organotellurium Chain Transfer Agent under Thermal and Photochemical Conditions”, Angew. Chem. Int. Ed. 2018, 57, 962-966 [Non-patent document 2] Sugihara, Y., Yamago, S., Zetterlund, Per B. “An Innovative Approach to Implementation of Organotellurium-Mediated Radical Polymerization (TERP) in Emulsion Polymerization”, Macromolecules 2015, 48,4312-4318 [Non-patent document 3] Yamago, S., Matsumoto, A., “Arylthiols as Highly Chemoselective and Environmentally Benign Radical Reducing Agents”, J. Org. Chem. 2008, 73, 7300-7304 Summary of the Invention [Problem to be solved by the invention]

[0008] Even in polymer particles composed of polymers with controlled structures synthesized by emulsion polymerization using the TERP method, organotellurium groups are bound to the growing ends of the polymers. Therefore, from the perspective of effective utilization of polymer particles and tellurium, an effective method for removing organotellurium groups from polymer particles composed of polymers synthesized by emulsion polymerization using the TERP method while maintaining the shape of the polymer particles is required. Note that a controlled-structure polymer refers to a polymer with a molecular weight dispersity of 1 to 2, preferably 1 to 1.5, for linear polymers, and a molecular weight dispersity of 1 to 4, preferably 1 to 2, for branched polymers.

[0009] However, there is no effective method yet for separating and recovering organotellurium groups from polymer particles obtained by emulsion polymerization using the TERP method without losing the useful characteristics of emulsion polymerization, i.e., without losing the controlled polymer particle shape. For example, when applying the methods described in Patent Documents 1 and 2 and Non-Patent Documents 1 and 2, which are used for polymers synthesized using the TERP method in a homogeneous solution system, it is necessary to dissolve the polymer particles in a solvent. Once the polymer particles are dissolved, it is difficult to re-form polymer particles with a controlled particle size, making it impossible to maintain the shape of the polymer particles, which is one of the useful characteristics obtained by emulsion polymerization.

[0010] Therefore, an object of the present invention is to provide a method for producing polymer particles that can separate organotellurium groups from polymer particles made of a polymer having organotellurium groups bonded to its growing terminal while maintaining the particle shape, thereby obtaining polymer particles with a sufficiently reduced amount of organotellurium groups. Another object of the present invention is to provide a method for obtaining a mixed solution containing polymer particles and an organotellurium compound, which enables such a method for producing polymer particles. Another object of the present invention is to propose a tellurium recovery method that can recover tellurium from polymer particles made of a polymer having organotellurium groups bonded to its growing terminal. Another object of the present invention is to provide a dispersion of polymer particles with a reduced tellurium concentration and controlled particle shape, which can be obtained by the above method for producing polymer particles. [Means for solving the problem]

[0011] The method for producing polymer particles according to the first aspect of the present invention includes: (i) a step of mixing polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at its growing ends, synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent, a dispersion A of the polymer particles A containing the polymer particles A and a first solvent for dispersing the polymer particles A, with a reactant soluble in the first solvent, and removing the organotellurium groups from the growing ends of the polymer to obtain a mixed solution containing a second organotellurium compound produced by a reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A; (ii) separating the mixture into the polymer particles B and a solution in which the second organotellurium compound is dissolved; Includes.

[0012] Here, in this specification, the "second organotellurium compound" includes all organotellurium compounds that may be present in the mixed solution after the reaction between the reactant and the organotellurium group. Therefore, for example, the second organotellurium compound also includes an organotellurium compound that is present in the mixed solution as a result of further reaction of an organotellurium compound produced by the reaction between the reactant and the organotellurium group.

[0013] A method for producing polymer particles according to a second aspect of the present invention includes: (i) a step of mixing polymer particles A made of a polymer with a controlled structure containing organotellurium groups at its growing ends, a dispersion A of the polymer particles A containing the polymer particles A and a solvent for dispersing the polymer particles A, with a reactant soluble in the solvent, and removing the organotellurium groups from the growing ends of the polymer to obtain a mixed solution containing an organotellurium compound produced by the reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A; (ii) separating the mixed solution into the polymer particles B and a solution in which the organotellurium compound is dissolved; Includes.

[0014] In a third aspect of the present invention, a method for obtaining a mixture containing polymer particles and an organotellurium compound includes mixing polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at its growing end, synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent, a dispersion A of the polymer particles A containing a solvent for dispersing the polymer particles A, and a reactant soluble in the solvent, and removing the organotellurium groups from the growing end of the polymer to obtain a mixture containing a second organotellurium compound produced by the reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced compared to the polymer particles A.

[0015] A method for recovering tellurium according to a fourth aspect of the present invention comprises: (I) a step of mixing polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at its growing terminals, synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent, a dispersion A of the polymer particles A containing a solvent for dispersing the polymer particles A, and a reactant soluble in the solvent to remove the organotellurium groups from the growing terminals of the polymer, thereby obtaining a mixed solution containing a second organotellurium compound produced by a reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A; (II) separating the mixture into the polymer particles B and a solution in which the second organotellurium compound is dissolved; and (III) recovering tellurium from the solution containing the second organotellurium compound obtained in step (II); Includes.

[0016] The dispersion of polymer particles according to the fifth aspect of the present invention comprises: the polymer constituting the polymer particles has a molecular weight dispersity of 1 or more and 2 or less when the polymer is a linear polymer, and a molecular weight dispersity of 1 or more and 4 or less when the polymer is a branched polymer; the tellurium concentration in the polymer particles is greater than 0 ppm by mass and less than or equal to 1000 ppm by mass; The particle diameter polydispersity index of the polymer particles is 0.7 or less. [Effects of the Invention]

[0017] According to the methods for producing polymer particles according to the first and second aspects of the present invention, the organotellurium groups can be separated from polymer particles made of a polymer with a controlled structure in which organotellurium groups are bonded to the growing ends while maintaining the particle shape, thereby obtaining polymer particles with a reduced amount of organotellurium groups.

[0018] According to the method for obtaining a mixed solution containing polymer particles and an organotellurium compound, which relates to the third aspect of the present invention, it is possible to obtain a mixed solution containing polymer particles and an organotellurium compound, which makes it possible to obtain the method for producing polymer particles, which is the invention according to the first and second aspects described above.

[0019] According to the method for recovering tellurium according to the fourth aspect of the present invention, tellurium can be recovered from polymer particles made of a polymer having an organotellurium group bonded to a growing end.

[0020] According to the polymer particle dispersion liquid of the fifth aspect of the present invention, it is possible to provide a polymer particle dispersion liquid in which the tellurium concentration is reduced and the particle shape is controlled. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram illustrating an embodiment of a method for producing polymer particles of the present invention. [Figure 2] 1H NMR chart of the product obtained in Experimental Example 4 using 2-aminoethanethiol as a reactant is shown. DETAILED DESCRIPTION OF THE INVENTION

[0022] (First embodiment) Hereinafter, an embodiment of the method for producing polymer particles of the present invention will be described.

[0023] The method for producing polymer particles of the present embodiment includes the steps of: (i) a step of mixing polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at its growing ends, synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent, a dispersion A of the polymer particles A containing the polymer particles A and a first solvent for dispersing the polymer particles A, with a reactant soluble in the first solvent, and removing the organotellurium groups from the growing ends of the polymer to obtain a mixed solution containing a second organotellurium compound produced by a reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A; (ii) separating the mixture into the polymer particles B and a solution in which the second organotellurium compound is dissolved; Includes.

[0024] According to the method for producing polymer particles of this embodiment, polymer particles A are synthesized by emulsion polymerization and consist of a polymer with a controlled structure in which organotellurium groups are bonded to the growing ends. The organotellurium groups are separated from the polymer particles A while maintaining the particle shape, thereby obtaining polymer particles B in which the organotellurium groups are reduced compared to polymer particles A.

[0025] For example, in step (i), polymer particles B are desirably obtained by removing organotellurium groups from the growing ends of the polymer constituting polymer particles A while maintaining the particle size and particle size distribution of polymer particles A. Generally, polymer particles made of a polymer obtained by emulsion polymerization have a highly controlled particle size and particle shape, as indicated by the particle size and the polydispersity index of the particle size. In the production method of this embodiment, it is possible to obtain polymer particles B having fewer organotellurium groups than polymer particles A by separating organotellurium groups from the growing ends of the polymer constituting polymer particles A while substantially maintaining the highly controlled particle shape of the polymer particles A. Therefore, polymer particles B can be obtained as a particle group with extremely high particle size uniformity. Here, "polymer particles B substantially maintain the shape of polymer particles A" means, for example, that the rate of change in the average particle size of the finally obtained polymer particles B relative to the average particle size of polymer particles A is within ±30%, preferably within ±20%, more preferably within ±15%, and that the rate of change in the polydispersity index of the particle size of polymer particles A relative to the polydispersity index of the particle size of polymer particles B is within ±50%, preferably within ±30%.

[0026] FIG. 1 is a schematic diagram illustrating a method for producing polymer particles according to this embodiment. As shown in FIG. 1, a dispersion 5 (dispersion A) is prepared, containing polymer particles 3 (polymer particles A) composed of a polymer 2 having organotellurium groups 1 at its growing ends and a first solvent 4 for dispersing the polymer particles 3. A reactant soluble in the first solvent 4 is mixed with the dispersion 5. Even after the reactant is mixed, the polymer particles 3 remain dispersed in a particle state. The reactant reacts with the organotellurium groups 1 contained in the polymer particles 3 to produce organotellurium compounds 6 (second organotellurium compounds), which are reaction products. The organotellurium groups 1 are separated from the polymer particles 3, resulting in polymer particles 7 (polymer particles B). This results in a mixture 8 containing the organotellurium compounds 6 and the polymer particles 7. Next, the mixture 8 is separated into the polymer particles 7 and a solution 9 in which the organotellurium compound 6 is dissolved. While the final polymer particles 7 are shown in a solid state in FIG. 1, the polymer particles 7 obtained through the separation process may be in a dispersion state in a solvent. Furthermore, although FIG. 1 shows a state in which all of the organotellurium groups 1 have been removed from the polymer particles 3 and the polymer particles 7 do not contain any organotellurium groups 1, the polymer particles 7 may contain trace amounts of the organotellurium groups 1 remaining or may contain trace amounts of organotellurium compounds produced from the separated organotellurium groups 1.

[0027] The method for producing polymer particles of this embodiment may further include a step (iii) of washing the polymer particles B (polymer particles 7 shown in FIG. 1) obtained in step (ii) with a second solvent, and in step (iii), the second organotellurium compound may be further separated from the polymer particles B. By including the washing step (iii) in the method for producing polymer particles of this embodiment, the second organotellurium compound that is mixed in trace amounts into the polymer particles B obtained by separation in step (ii) is separated from the polymer particles B by the washing in step (iii). This makes it possible to obtain polymer particles B with a higher purity in which the amount of mixed organotellurium compound is further reduced. The tellurium concentration in polymer particles B is, for example, 1000 ppm by mass or less, desirably 500 ppm by mass or less, more desirably 100 ppm by mass or less, and even more desirably 50 ppm by mass or less, or the tellurium concentration relative to the initial tellurium concentration in polymer particles A is 70% by mass or less, desirably 60% by mass or less, more desirably 50% by mass or less, even more desirably 20% by mass or less, and even more desirably 5% by mass or less.

[0028] Each of the steps (i) to (iii) will be explained in more detail below.

[0029] [Process (i)] Dispersion A is prepared, containing polymer particles A and a first solvent for dispersing the polymer particles A. The polymer particles A are typically composed of a polymer with a controlled structure synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent. Therefore, the first solvent may be the solvent used during emulsion polymerization. In other words, the dispersion of polymer particles A obtained by emulsion polymerization can be used as is as dispersion A.

[0030] The first organotellurium compound is not particularly limited as long as it can be used as a polymerization inhibitor in emulsion polymerization. For example, the first organotellurium compound can be an organotellurium compound represented by the following general formula (1): [ka]

[0031] In the above formula (1), R 1 R represents an alkyl group having 1 to 12 carbon atoms which may be branched (hereinafter, an alkyl group which may be branched will be simply referred to as an "alkyl group"), an aryl group, or an aromatic heterocyclic group. 1 The alkyl group, aryl group, or aromatic heterocyclic group may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group.

[0032] In the above formula (1), R 2 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amido group, an oxycarbonyl group, a cyano group, an allyl group, or a propargyl group, and each group may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxy group, and a sulfo group.

[0033] R 4 is an alkyl group having 1 to 12 carbon atoms, an aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amido group, an oxycarbonyl group, a cyano group, an allyl group, or a propargyl group, and each of these groups may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxy group, and a sulfo group.

[0034] As mentioned above, R 1 The group represented by the formula (I) is an alkyl group having 1 to 12 carbon atoms, an aryl group, or an aromatic heterocyclic group, and examples thereof include the following groups.

[0035] Examples of alkyl groups having 1 to 12 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl, and cyclic alkyl groups such as cyclohexyl. Each of these groups may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group. The alkyl group having at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group, and its structure is not limited. The ether group and amino group of the alkyl group may be a polyether group and a polyamino group. For example, a polyethylene glycol group (-(CHCHO) n Furthermore, there are also polyethylene glycol groups in which the hydrogen atom at the end of the group is substituted with an alkyl group (-(CH2CH2O) n R (R: alkyl group)). Also, NH is used instead of O in the polyethylene glycol group, and the terminal is H (-(CHCHNH) n H) or those with an alkyl group at the end (-(CH2CH2NH) n R (R: alkyl group)) may also be used.

[0036] The aryl group includes a phenyl group, a naphthyl group, and the like, and each group may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group.

[0037] Examples of aromatic heterocyclic groups include pyridyl, furyl, and thienyl groups, each of which may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group.

[0038] R2 ~R 4 Examples of the alkyl group, aryl group, substituted aryl group, aromatic heterocyclic group, alkoxy group, acyl group, amido group, oxycarbonyl group, cyano group, allyl group, or propargyl group having 1 to 12 carbon atoms represented by the following formula include the following groups.

[0039] Examples of the alkyl group having 1 to 12 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups, and cyclic alkyl groups such as cyclohexyl groups, and each of these groups may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group.

[0040] The aryl group includes a phenyl group, a naphthyl group, and the like, and each group may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group.

[0041] Examples of aromatic heterocyclic groups include pyridyl, furyl, and thienyl groups, each of which may have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group.

[0042] The alkoxy group is preferably a group in which an alkyl group having 1 to 12 carbon atoms is bonded to an oxygen atom, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tet-butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an undecyloxy group, or a dodecyloxy group, and may further have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxy group, and a sulfo group on each carbon chain.

[0043] The acyl group may be an acetyl group, a propionyl group, a benzoyl group, or the like, and may further have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group on each carbon chain.

[0044] The amide group is -CONR 41 R 42 (R 41 , R 42 are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group, and may further have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group on each carbon chain.

[0045] The oxycarbonyl group is -COOR 43 (R 43 is preferably a group represented by (wherein R is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group), such as 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, or a phenoxycarbonyl group, and each of the carbon chains may further have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxy group, and a sulfo group. The oxycarbonyl group may be a salt of a carboxy group.

[0046] The aryl group is -CR 44 R 45 -CR 46 =CR 47 R 48 (R 44 , R 45 are each independently a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, R 46 , R 47 , R 48are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group, and each substituent may be connected in a cyclic structure), and each may further have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxyl group, and a sulfo group on its carbon chain.

[0047] The propargyl group is -CR 49 R 50 -C≡CR 51 (R 49 , R 50 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, R 51 is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, or a silyl group), and may further have at least one functional group selected from the group consisting of an ether group, a hydroxyl group, an amino group, a carboxy group, and a sulfo group on each carbon chain.

[0048] The first organotellurium compound used as a polymerization inhibitor in emulsion polymerization is not particularly limited, and may be appropriately selected depending on the type of polymer synthesized by emulsion polymerization, etc. When the solvent used in emulsion polymerization is a first solvent, a compound that dissolves in the first solvent is used as the first organotellurium compound. In this case, in the case of oil-in-water emulsion polymerization using water as the first solvent, it is preferable that the first organotellurium compound has a highly hydrophilic group, and in the case of water-in-oil emulsion polymerization using an organic solvent as the first solvent, it is preferable that the first organotellurium compound has a highly hydrophobic group.

[0049] The first solvent may be any solvent that can dissolve the reactants but does not dissolve the polymer particles A. For example, the first solvent may be selected arbitrarily depending on the conditions, such as oil-in-water emulsion polymerization using water as the first solvent or water-in-oil emulsion polymerization using an organic solvent as the first solvent.

[0050] The reactant is not particularly limited as long as it is a compound that is soluble in the first solvent and can react efficiently with the organotellurium group. Here, in this specification, "a reactant is soluble in a solvent" means that the reactant is soluble to the extent that it can react as a solute, and does not necessarily have to be completely dissolved. The reactant preferably has, for example, a first substituent that reacts with the organotellurium group contained in the growing end of the polymer particle A and at least one second substituent that has affinity with the first solvent. The second substituent preferably has a higher affinity with the first solvent. By having such a first substituent and second substituent, the reactant is soluble in the first solvent and can react with the organotellurium group contained in the growing end of the polymer particle A to cleave the organotellurium group from the polymer.

[0051] The reactant may be, for example, a reducing agent. Examples of the first substituent that reacts with tellurium include a thiol group, a selenol group, and a tellurol group.

[0052] For example, when the first solvent contains water, the second substituent is preferably at least one selected from the group consisting of a carboxyl group and its salt, an amino group and its salt, an amide group, a hydroxyl group, a sulfo group and its salt, and an ether group. By containing such a second substituent, the reactant is easily dissolved in the first solvent containing water, and can react efficiently with the organotellurium group contained in the growing end of the polymer particle A.

[0053] The thiol may be represented, for example, by the following formula (2): R 5 -SH...(2) In the above formula (2), R 5R is an aryl group having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group, or an alkyl group having 1 to 12 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms) and having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group. 5 In the formula (I), the aryl group having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group is not limited in structure as long as it has at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group. 5 Examples of thiols having an aryl group in R include p-mercaptobenzoic acid, m-mercaptobenzoic acid, and o-mercaptobenzoic acid. 5 In the above, the alkyl group having at least one functional group selected from the group consisting of an ether group, a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, and a sulfo group and its salts is not limited in structure as long as it has at least one functional group selected from the group consisting of an ether group, a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, and a sulfo group and its salts. The ether group and amino group of the alkyl group may be a polyether group and a polyamino group. As an example, a polyethylene glycol group (-(CH2CHO) n Furthermore, there are also polyethylene glycol groups in which the hydrogen atom at the end of the group is substituted with an alkyl group (-(CH2CH2O) n R (R: alkyl group)). Also, NH is used instead of O in the polyethylene glycol group, and the terminal is H (-(CHCHNH) n H) or those with an alkyl group at the end (-(CH2CH2NH) nR (R: alkyl group) may also be used. This thiol is suitable when the first solvent contains water.

[0054] Tellurol may be represented by, for example, the following formula (3): R 6 -Te-H …(3) In the above formula (3), R 6 R is an aryl group having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group, or an alkyl group having 1 to 12 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms) and having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group. 6 In the formula (I), the aryl group having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group is not limited in structure as long as it has at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group. 6 In the above, the alkyl group having at least one functional group selected from the group consisting of an ether group, a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, and a sulfo group and its salts is not limited in structure as long as it has at least one functional group selected from the group consisting of an ether group, a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, and a sulfo group and its salts. The ether group and amino group of the alkyl group may be a polyether group and a polyamino group. As an example, a polyethylene glycol group (-(CH2CHO) n Furthermore, there are also polyethylene glycol groups in which the hydrogen atom at the end of the group is substituted with an alkyl group (-(CH2CH2O) nR (R: alkyl group)). Also, NH is used instead of O in the polyethylene glycol group, and the terminal is H (-(CHCHNH) n H) or those with an alkyl group at the end (-(CH2CH2NH) n R (R: alkyl group)) may also be used. This tellurol is suitable when the first solvent contains water.

[0055] When the first solvent contains water, the selenol may be represented, for example, by the following formula (4): R 7 -Se-H …(4) In the above formula (4), R 7 R is an aryl group having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group, or an alkyl group having 1 to 12 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms) and having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group. 7 In the formula (I), the aryl group having at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group is not limited in structure as long as it has at least one functional group selected from the group consisting of a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, a sulfo group and its salts, and an ether group. 7In the above, the alkyl group having at least one functional group selected from the group consisting of an ether group, a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, and a sulfo group and its salts is not limited in structure as long as it has at least one functional group selected from the group consisting of an ether group, a carboxy group and its salts, a hydroxyl group, an amino group and its salts, an amide group, and a sulfo group and its salts. The ether group and amino group of the alkyl group may be a polyether group and a polyamino group. As an example, a polyethylene glycol group (-(CH2CHO) n Furthermore, there are also polyethylene glycol groups in which the hydrogen atom at the end of the group is substituted with an alkyl group (-(CH2CH2O) n R (R: alkyl group)). Also, NH is used instead of O in the polyethylene glycol group, and the terminal is H (-(CHCHNH) n H) or those with an alkyl group at the end (-(CH2CH2NH) n R (R: alkyl group)) may also be used. This selenol is suitable when the first solvent contains water.

[0056] The amount of reactant to be mixed with dispersion A of polymer particles A can be determined taking into consideration the amount of organotellurium groups contained in the growing ends of the polymers constituting polymer particles A. For example, the reactant may be mixed in an amount of 1.0 to 10.0 mol, and preferably 1.0 to 2.0 mol, per 1 mol of organotellurium groups contained in the growing ends of the polymers contained in dispersion A of polymer particles A.

[0057] After the reactant reacts with the organotellurium group 1 contained in the polymer particles 3 to produce the reaction product, organotellurium compound 6 (second organotellurium compound), an appropriate reactant that reacts with the second substituent derived from the reactant may be added to increase the solubility of the organotellurium compound 6 in the first solvent. This allows for efficient separation of the reactant from the organotellurium group. For example, when water is used as the first solvent, if the second substituent derived from the reactant is a carboxyl group, a base such as sodium hydroxide may be added to the mixture, or if the second substituent derived from the reactant is an amino group, an acid such as hydrochloric acid may be added to the mixture. In this example, the hydrophilicity of the reactant is improved by the salt produced by the reaction with the second substituent derived from the reactant by adding a base or acid.

[0058] The reaction temperature and reaction time for reacting the organotellurium group at the growing end of the polymer with the reactant are not particularly limited, and can be appropriately adjusted depending on the organotellurium group and the reactant used. For example, the reaction is carried out at a reaction temperature in the range of 0°C to 100°C for a reaction time in the range of 0.1 to 24 hours while stirring the mixture. Light irradiation may be performed to promote the reaction.

[0059] Step (i) in the method for producing polymer particles of this embodiment can be considered as "a method for obtaining a mixture containing polymer particles and an organotellurium compound." In other words, step (i) can be described as "a method for obtaining a mixture containing polymer particles and an organotellurium compound, comprising: polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at the growing end, synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent; a dispersion A of the polymer particles A, which includes a solvent for dispersing the polymer particles A; and a reactant soluble in the solvent, to remove the organotellurium groups from the growing end of the polymer, thereby obtaining a mixture containing a second organotellurium compound produced by the reaction between the reactant and the organotellurium groups; and polymer particles B, in which the organotellurium groups are reduced compared to the polymer particles A." Details of the method for obtaining a mixture containing polymer particles and an organotellurium compound are the same as those described above in detail for step (i), and therefore will not be described here.

[0060] [Step (ii)] The mixture obtained in step (i), which contains the second organotellurium compound produced by the reaction between the reactant and the organotellurium groups, and polymer particles B, which have fewer organotellurium groups than polymer particles A, is separated into polymer particles B and a solution in which the second organotellurium compound is dissolved. In this step (ii), any method can be used as long as it can separate the mixture into polymer particles B and a solution in which the second organotellurium compound is dissolved, but for example, solid-liquid separation can be used for separation.

[0061] Known solid-liquid separation methods can be applied to the solid-liquid separation method used in the polymer particle production method of this embodiment. Therefore, an appropriate method can be selected from known solid-liquid separation methods, taking into account the particle size of the polymer particles B, etc. For example, centrifugal sedimentation or filtration can be used. Filtration methods include pressure filtration, which applies pressure to the liquid, suction (vacuum) filtration, centrifugal filtration, etc., and cross-flow filtration and dead-end filtration, etc., depending on the direction of the liquid flow relative to the membrane. Any of these methods can be used. Among these, centrifugal filtration and cross-flow filtration are particularly preferred because they can separate the mixed liquid into polymer particles, or a solution in which the polymer particles are dispersed, and a solution in which the second organotellurium compound is dissolved, in a short period of time. The filter material used is not particularly limited, and an appropriate filter material can be selected from known filter materials, taking into account the particle size of the polymer particles B, etc.

[0062] In step (ii), when separating the polymer particles B from the solution in which the second organotellurium compound is dissolved, a solvent may be added to the mixture, for example, as a diluent. The solvent used as a diluent is preferably a solvent that has affinity with the first solvent and does not dissolve the polymer particles B. For example, when the first solvent contains water, the solvent used as a diluent in step (ii) is preferably a solvent that is infinitely dilutable with water and does not dissolve the polymer particles B. Examples of such solvents include one solvent selected from the group consisting of water, alcohols, amides, ketones, and alkyl sulfoxides, or a mixed solvent of two or more thereof.

[0063] The polymer particles B obtained in step (ii) may be in the form of a dispersion B in which the polymer B is dispersed in, for example, the first solvent or a mixed solvent containing the first solvent and the solvent added as a diluent in the separation step.

[0064] [Step (iii)] As described above, the method for producing polymer particles of this embodiment may further include step (iii) of washing the polymer particles B obtained in step (ii) with a second solvent. The second solvent used in this washing step is a solvent that has affinity with the first solvent and does not dissolve the polymer particles B. The solvent that does not dissolve the polymer particles B may be any solvent that does not dissolve the polymer particles B to the extent that, when the solvent and the polymer particles B are mixed, the rate of change in the average particle size and polydispersity index of the polymer particles B does not change by more than ±30% and more than ±50%, respectively.

[0065] When the first solvent contains water, the second solvent is preferably a solvent that is infinitely dilutable with water and does not dissolve polymer particles B. In this case, the second solvent is preferably one solvent selected from the group consisting of water, alcohols, amides, ketones, and alkyl sulfoxides, or a mixture of two or more solvents. By washing polymer particles B with such a second solvent, the organotellurium compound in the polymer particle B dispersion solution can be further reduced.

[0066] The washing step of step (iii) may be repeated multiple times. In this case, the same type of solvent may be used as the second solvent each time, or multiple types of solvents may be used as the second solvent. For example, washing using water as the second solvent and washing using an alcohol such as methanol as the second solvent may both be performed. In this way, washing polymer particles B using different types of second solvents can further reduce the amount of organotellurium compounds from the polymer particle dispersion solution, and the purity of the resulting polymer particles B can sometimes be further improved.

[0067] According to the method for producing polymer particles of this embodiment, the tellurium concentration in the finally obtained polymer particles B is reduced compared to that in the polymer particles A, and the tellurium concentration can be reduced to 70% by mass or less, preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 20% by mass or less, and even more preferably 5% by mass or less relative to the initial tellurium concentration in the polymer particles A. This allows the tellurium concentration in the polymer particles B to be reduced to 1000 ppm by mass or less, preferably 500 ppm by mass or less, and more preferably 50 ppm by mass or less.

[0068] In this embodiment, a method for producing polymer particles has been described in which organotellurium groups are separated from polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at its growing ends, which polymer particles A have been synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent. However, the method of the present invention for separating organotellurium groups contained at the growing ends of a polymer from the polymer is not limited to polymers synthesized by emulsion polymerization, but can also be applied as a method for separating organotellurium groups from polymers containing organotellurium groups at their growing ends, regardless of the polymerization method of the polymer.

[0069] That is, in another embodiment, the method for producing polymer particles of the present invention comprises the steps of: (i) a step of mixing polymer particles A made of a polymer with a controlled structure containing organotellurium groups at its growing ends, a dispersion A of the polymer particles A containing the polymer particles A and a solvent for dispersing the polymer particles A, with a reactant soluble in the solvent, and removing the organotellurium groups from the growing ends of the polymer to obtain a mixed solution containing an organotellurium compound produced by the reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A; (ii) separating the mixed solution into the polymer particles B and a solution in which the organotellurium compound is dissolved; The method may also include a method for producing polymer particles, comprising:

[0070] The type of polymer obtained by the method for producing polymer particles of this embodiment is typically a polymer that can be synthesized by emulsion polymerization, but is not limited to this and can also be applied to, for example, suspension polymerization or dispersion polymerization.

[0071] (Second embodiment) Hereinafter, an embodiment of the tellurium recovery method of the present invention will be described.

[0072] The tellurium recovery method of this embodiment includes the steps of: (I) a step of mixing polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at its growing terminals, synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent, a dispersion A of the polymer particles A containing a solvent for dispersing the polymer particles A, and a reactant soluble in the solvent to remove the organotellurium groups from the growing terminals of the polymer, thereby obtaining a mixed solution containing a second organotellurium compound produced by a reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A; (II) separating the mixture into the polymer particles B and a solution in which the second organotellurium compound is dissolved; and (III) recovering tellurium from the solution containing the second organotellurium compound obtained in step (II); Includes.

[0073] In the tellurium recovery method of this embodiment, the above steps (I) and (II) are the same as steps (i) and (ii), respectively, in the polymer particle production method described in the first embodiment, and therefore detailed explanations thereof will be omitted here.

[0074] The tellurium recovery method of this embodiment further includes a step (III) of recovering tellurium from the solution containing the second organotellurium compound obtained in the step (II). As a method for recovering tellurium from a solution, any known method for recovering tellurium from a solution can be appropriately selected and used. One example is a method in which an inorganic iodine compound is added to the solution containing the second organotellurium compound, sulfur oxide is further supplied to precipitate the tellurium in the solution, and then solid-liquid separation is performed to recover the tellurium.

[0075] (Third embodiment) Hereinafter, embodiments of the polymer particle dispersion of the present invention will be described.

[0076] The polymer particle dispersion of this embodiment is, for example, a dispersion of polymer particles made of a polymer with a controlled structure synthesized by emulsion polymerization using an organotellurium compound as a polymerization control agent, and is subjected to a process for separating organotellurium groups contained in the growing ends of the polymer, thereby reducing the tellurium concentration compared to polymer particles made of a polymer immediately after synthesis. In the polymer particle dispersion of this embodiment, the tellurium concentration of the polymer particles exceeds 0 ppm by mass and is 1000 ppm by mass or less, preferably 500 ppm by mass or less, and more preferably 50 ppm by mass or less. In this embodiment, it is also possible to realize polymer particles with a tellurium concentration reduced to 10 ppm by mass or less. When the tellurium concentration of the polymer particles in the dispersion of this embodiment is expressed as a ratio to the tellurium concentration in the polymer particles before treatment to separate the organic tellurium groups contained in the growing ends of the polymer (initial tellurium concentration), the tellurium concentration of the polymer particles in the dispersion of this embodiment is 70 mass% or less, preferably 60 mass% or less, more preferably 50 mass% or less, more preferably 20 mass% or less, and even more preferably 5 mass% or less, of the initial tellurium concentration in the polymer particles.

[0077] In the dispersion of polymer particles of this embodiment, the polydispersity index of the particle diameter of the polymer particles is 0.7 or less, preferably 0.5 or less.

[0078] In the polymer particle dispersion finally obtained in this embodiment, the particle size polydispersity index of the polymer particles is controlled to 0.7 or less, and the tellurium concentration is very low, at 1000 mass ppm or less. A polymer particle dispersion in which the particle size polydispersity index is controlled in such a range is generally considered to be synthesized by the production method described in the first embodiment. In the polymer particle dispersion finally obtained in this embodiment, the particle size distribution is narrowly controlled, but the concentration of the organotellurium compound is very low. Therefore, the polymer particle dispersion of this embodiment is an extremely useful polymer particle dispersion in which the particle size polydispersity index is highly controlled and the concentration of the organotellurium compound is very low, which could not be achieved by conventional methods.

[0079] In the polymer particle dispersion finally obtained in this embodiment, the average particle size of the polymer particles is, for example, 1 nm or more and 100 μm or less, preferably 1 μm or less. In this way, in the polymer particle dispersion finally obtained in this embodiment, the average particle size of the polymer particles can be set to 1 nm or more and 100 μm or less. Therefore, the polymer particle dispersion of this embodiment is an extremely useful polymer particle dispersion in that the average particle size is controlled and the concentration of the organotellurium compound is very low, which could not be achieved by conventional methods.

[0080] In this specification, the polydispersity index and average particle size of polymer particles are determined by photon correlation spectroscopy of dynamic light scattering. This measurement can be performed using a measuring instrument described below.

[0081] The polymer constituting the dispersion of polymer particles of this embodiment described here satisfies the following conditions: for linear polymers, the molecular weight dispersity is 1 or more and 2 or less, more preferably 1 or more and 1.5 or less; for branched polymers, the molecular weight dispersity is 1 or more and 4 or less, more preferably 1 or more and 2 or less. The polymer constituting the dispersion of polymer particles of this embodiment preferably exhibits monodispersity in molecular weight. The polymer constituting the dispersion of polymer particles of this embodiment preferably exhibits unimodal molecular weight dispersity. Here, the molecular weight dispersity is determined by the number average molecular weight M n Weight average molecular weight M w Ratio of M w / M n and represents the molecular weight distribution. A polymer having a molecular weight dispersity that satisfies the above range is a polymer having a very uniform molecular weight. Therefore, a dispersion of polymer particles made of a polymer that satisfies the above range of dispersity has a uniform molecular weight and is therefore potentially applicable to a variety of uses and is extremely useful.

[0082] The polymer constituting the polymer particles of this embodiment is not particularly limited as long as it can be synthesized by emulsion polymerization using the TERP method. Examples of such polymers include homopolymers, random copolymers, sequence-controlled copolymers, and block copolymers, and polymers with different structures such as linear and branched structures. The molecular weight is not limited to suit the application, but the molecular weight distribution is characterized by a unimodal distribution. [Example]

[0083] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples.

[0084] <Reactant study> First, we investigated the reagents used to separate organotellurium groups from the growing ends of polymers. Specifically, we clarified how the structure of the thiol used to reduce the growing ends of polymers, expressed by the above formula (2), relates to its reactivity, and we also investigated whether the molecules of the organotellurium compound (corresponding to the second organotellurium compound) produced by reduction can be solubilized in water using the following model experiments.

[0085] As a model small molecule that generates acrylate radicals, an organotellurium compound (corresponding to the first organotellurium compound) that can be used as a polymerization control agent during polymer polymerization in the present invention was used. As a specific example, an organotellurium compound represented by the following formula (5) was used. [ka]

[0086] To improve the water solubility of the resulting organotellurium compound, thiols with carboxyl groups and thiols with amino groups were selected as examples of reactants. As thiols with carboxyl groups, o-mercaptobenzoic acid (Experimental Example 1) represented by the following formula (6), m-mercaptobenzoic acid (Experimental Example 2) represented by the following formula (7), and p-mercaptobenzoic acid (Experimental Example 3) represented by the following formula (8) were used. As thiol with amino groups, 2-aminoethanethiol (HSCH2CH2NH2) (Experimental Example 4) was used.

[0087] [ka]

[0088] [ka]

[0089] [ka]

[0090] The organotellurium compound represented by formula (5) above and mercaptobenzoic acid (1.3 equivalents) represented by any of formulas (6) to (8) above were dissolved in dimethyl sulfoxide-D6 (DMSO-d6), and then reduced under irradiation at 65°C using a 6W white light-emitting diode (LED) lamp until the conversion rate of the organotellurium compound reached 100%. The o-mercaptobenzoic acid of formula (6) above was completely consumed beyond the equivalence relationship, but the other thiols (m-mercaptobenzoic acid and p-mercaptobenzoic acid) were consumed in an equivalence relationship with the organotellurium compound.

[0091] Products that can be produced by the reaction of the above-mentioned organotellurium compound with mercaptobenzoic acid or 2-aminoethanethiol include an ester compound (product 1) represented by the following formula (9), a reduction product (product 2) represented by the following formula (10), a ditelluride (product 3) represented by the following formula (11), and a compound (product 4) represented by the following formula (12).

[0092] (CH3)2CHCOOC2H5…(9) RS-TeCH3…(10) (TeCH3)2…(11) RSSR...(12) Here, in the above formulas (10) and (12), R is a 2-carboxyphenyl group (Experimental Example 1), a 3-carboxyphenyl group (Experimental Example 2), a 4-carboxyphenyl group (Experimental Example 3), or a 2-aminoethyl group (Experimental Example 4).

[0093] Table 1 below shows the yields of products 1 to 4 in Experimental Examples 1 to 4.

[0094] [Table 1]

[0095] In Experiments 1 and 2, using o-mercaptobenzoic acid and m-mercaptobenzoic acid as reactants, respectively, the yield of the ester compound (Product 1) was approximately 85%, demonstrating the high reduction efficiency of these reactants. The ditelluride (Product 3) produced here was water-insoluble. The formation of ditelluride (Product 3) indicates that the reduction product (Product 2) is unstable and gradually decomposes into ditelluride (Product 3) and the compound represented by formula (12) (Product 4). In Experiment 3, using p-mercaptobenzoic acid with a para-carboxyl group, the ester compound (Product 1) was obtained in high yield, and the yield of the reduction product (Product 2) was also over 90%. This result indicates the stability of the reduction product (Product 2). Therefore, using p-mercaptobenzoic acid as a reactant is considered advantageous for recovering tellurium compounds separated from polymers by reduction reactions.

[0096] When 2-aminoethanethiol having an amino group was used as the reactant (Experimental Example 4), the reaction was completed immediately after mixing it with the organotellurium compound represented by the above formula (5) in a solvent. 1 This was confirmed by the peak of the TeMe group in H NMR. The yield of the ester compound (product 1) was 95%. On the other hand, the peak of the reduction product (product 2) disappeared in less than 10 minutes, and the peaks of the ditelluride (product 3) and the compound represented by formula (12) (product 4) were observed. These two compounds were extracted in the post-treatment and then purified using CDCl3 as the solvent. 1 The structure was determined by H NMR (see Figure 2). This result indicates that the reduction product (product 2) generated from a thiol with an amino group is unstable and spontaneously decomposes to generate ditelluride (product 3). When an organotellurium compound represented by formula (5) above is used, a hydrophobic ditelluride is obtained. However, when an organotellurium compound with a hydrophilic substituent bonded to the tellurium is used, a ditelluride that can be separated and recovered as a water-soluble compound can be directly obtained, which is expected to be an effective method for recycling tellurium.

[0097] <Example> Example 1 [Synthesis of polymers by emulsion polymerization] In a nitrogen atmosphere, a polymerization inhibitor (1.5 mg, 5.0 μmol) and hexadecyltrimethylammonium bromide (CTAB, 260 mg, 4.3 mass % relative to water) were added to a glass tube. The polymerization inhibitor used was an organotellurium compound represented by the following formula (13). [ka]

[0098] In the glass tube, add degassed deionized water (6.0 mL) and an aqueous solution of sodium hydroxide (10 μL, 0.51 mol L). -1 Further addition of styrene (0.58 mL, 5.0 mmol) as a monomer resulted in a homogeneous solution. This solution was mixed with styrene (0.58 mL, 5.0 mmol) as a monomer to obtain a mixture. The resulting mixture was heated at 80°C for 6 hours while stirring under a 6 W white light-emitting diode (LED) lamp. A small amount (approximately 100 μL) of the reaction mixture was periodically removed, and the organic matter was extracted from the removed reaction mixture with deuterated chloroform. After separating and drying the deuterated chloroform phase, 1 The degree of monomer conversion was measured by H NMR. The degree of styrene conversion reached 90% after 6 hours. The final reaction mixture was a dispersion of polymer particles in water (corresponding to the first solvent).

[0099] A small amount (approximately 100 μL) of the dispersion was taken out of the reaction mixture, and the polymer was extracted with chloroform. The resulting polymer was analyzed by size exclusion chromatography (SEC). As a result, the number average molecular weight M nThe results indicated the formation of polystyrene with a molecular weight of 91,200 and a molecular weight dispersity of 1.26. A separate portion of this dispersion (approximately 10 μL) was diluted with deionized water (approximately 5.0 mL) to prepare a sample for measuring polymer particles. The average particle size and particle size polydispersity index of the polymer particles in this sample were measured using a light scattering device (Otsuka Electronics Co., Ltd., ELSZ-1000ZSY). The polymer particles had an average particle size of 200.4 nm and a particle size polydispersity index of 0.50.

[0100] Table 2 shows the results of measuring the above-mentioned physical properties of the polymer particles made of the polymer synthesized in this example.

[0101] [Separation of organotellurium groups from the growing ends of polymers] As a reactant soluble in water, which is the first solvent, p-mercaptobenzoic acid represented by the above formula (8) was used.

[0102] This p-mercaptobenzoic acid (7.5 μmol) and an aqueous solution of sodium hydroxide (15 μL, 0.51 mol L -1 An aqueous solution was prepared by dissolving 7.5 μmol of PEG-100 in 2.0 mL of degassed deionized water. This aqueous solution was mixed with 6 mL of the dispersion, and the resulting mixture was heated at 80°C for 4 hours while stirring under a 6 W white LED lamp.

[0103] After heating, degassed deionized water (approximately 52 mL) was added to the mixture to make a total volume of 60 mL. The resulting mixture was transferred to a plastic container (Pall, Jumbosep) equipped with a membrane filter for centrifugal filtration (Pall, Membrane Inserts 300K). This container was placed in a centrifuge (As One, Violamo 444315-100), and the mixture was centrifuged at G = 1,500. This concentrated the mixture to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and an aqueous solution separated from the mixture.

[0104] Next, the polymer particles contained in the mixture concentrated to approximately 8 mL were washed. Specifically, first, degassed deionized water (approximately 52 mL) was added to the concentrated mixture (8 mL) to make a total volume of 60 mL, and this mixture was concentrated to approximately 8 mL using the same centrifugal filtration method as above. This procedure was repeated twice. Next, degassed methanol (approximately 52 mL) was added to the concentrated mixture (8 mL) to make a total volume of 60 mL, and the resulting mixture was concentrated to approximately 8 mL using the same centrifugal filtration method as above. This procedure was repeated twice.

[0105] The aqueous solution or methanol solution separated by the nth centrifugal filtration is referred to as aqueous solution n or methanol solution n. The aqueous solution separated by the first centrifugal filtration is referred to as aqueous solution 1. The tellurium concentrations in the separated aqueous solutions 1, 2, 3, 4, and 5 (a total of five samples) were measured using ICP-AES, as described below. The tellurium recovery rate determined from the results was 96.3%. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium concentration in the resulting polymer sample was determined to be 47.4 ppm (3.7% residual). The residual tellurium rate was calculated using a theoretical initial tellurium concentration of 1,280 ppm. Table 3 shows the tellurium recovery rate and the residual tellurium concentration and rate in the polymer sample.

[0106] Example 2 [Synthesis of polymers by emulsion polymerization] In a nitrogen atmosphere, a polymerization inhibitor (1.6 mg, 5.0 μmol) and CTAB (260 mg, 4.3 mass % relative to water) were added to a glass tube. The polymerization inhibitor used was an organotellurium compound represented by the following formula (14). [ka]

[0107] In the glass tube, add degassed deionized water (6.0 mL) and an aqueous solution of sodium hydroxide (10 μL, 0.51 mol L). -1Further addition of styrene (0.58 mL, 5.0 mmol) as a monomer resulted in a homogeneous solution. This solution was mixed with styrene (0.58 mL, 5.0 mmol) as a monomer to obtain a mixture. The resulting mixture was heated at 80°C for 3 hours while stirring under a 6 W white light-emitting diode (LED) lamp. A small amount (approximately 100 μL) of the reaction mixture was then removed, and the organic matter was extracted from the removed reaction mixture with deuterated chloroform. The deuterated chloroform phase was separated and dried, and then 1 The degree of monomer conversion was measured by H NMR. The degree of styrene conversion reached 95% after 3 hours. The final reaction mixture was a dispersion of polymer particles in water (corresponding to the first solvent).

[0108] A small amount (about 100 μL) of the dispersion was taken out from the above dispersion, and the polymer was extracted from the reaction mixture with chloroform. The number average molecular weight M n The number average molecular weight M and the polydispersity of the molecular weight were analyzed by SEC in the same manner as in Example 1. Another portion (about 10 μL) of this dispersion was diluted with deionized water (about 5.0 mL) to prepare a sample for measuring the polymer particles. This sample was used to measure the average particle size and the polydispersity index of the polymer particles using the same light scattering device as in Example 1. For the polymer synthesized in Example 2, the number average molecular weight M n The molecular weight dispersity, average particle size, and particle size polydispersity index are shown in Table 2.

[0109] [Separation of organotellurium groups from the growing ends of polymers] p-Mercaptobenzoic acid, which was used in Example 1, was used as the reactant soluble in water, the first solvent. This thiol (7.5 μmol) was dissolved in 2.0 mL of degassed deionized water to obtain an aqueous solution, which was then added to 6 mL of the dispersion to obtain a mixed solution. Next, an aqueous sodium hydroxide solution (15 μL, 0.51 mol L) was added to this mixed solution. -1 The resulting mixture was heated at 80° C. for 4 hours with stirring under a 6 W white LED lamp.

[0110] Degassed deionized water (approximately 50 mL) was added to the heated mixture to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and an aqueous solution separated from the mixture.

[0111] Next, the polymer particles contained in the mixture concentrated to about 8 mL were washed. Specifically, degassed deionized water (about 50 mL) was added to the concentrated mixture (8 mL), and the resulting mixture was concentrated to about 8 mL by centrifugal filtration in the same manner as in Example 1. This procedure was repeated twice.

[0112] As in Example 1, the aqueous solution separated by the nth centrifugal filtration is referred to as aqueous solution n. The tellurium concentrations in the separated aqueous solutions 1, 2, and 3 (a total of three samples) were measured by ICP-AES, as described below. The tellurium recovery rates calculated from the tellurium concentration measurements in aqueous solutions 1, 2, and 3 were as shown in Table 3. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium rate in the obtained polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual tellurium concentration and residual rate in the polymer sample are shown in Table 3.

[0113] In Example 2, a portion (approximately 10 μL) of the concentrated mixture obtained after washing the polymer particles by centrifugal filtration was diluted with degassed deionized water (approximately 5.0 mL) to prepare a sample for measuring the polymer particles. Using this sample, the average particle size and particle size polydispersity index of the polymer particles were measured using the same light scattering device as in Example 1. The results are shown in Table 4. Table 4 also shows the rate of change in the average particle size and the particle size polydispersity index of the final polymer particles (polymer particles B) obtained after washing the polymer particles compared to the polymer particles (polymer particles A) before separation of the organotellurium groups and washing the polymer particles.

[0114] Example 3 [Synthesis of polymers by emulsion polymerization] In Example 3, a polymer was synthesized in the same manner as in Example 2. The number average molecular weight M n The molecular weight dispersity, average particle size, and particle size polydispersity index were measured. The measurement results are shown in Table 2.

[0115] [Separation of organotellurium groups from the growing ends of polymers] As the reactant soluble in water, which was the first solvent, p-mercaptobenzoic acid, which was used in Example 1, was used. This thiol (7.5 μmol) and an aqueous solution of sodium hydroxide (15 μL, 0.51 mol / L) were mixed. -1 An aqueous solution was prepared by dissolving 7.5 μmol of PEG-100 in 2.0 mL of degassed deionized water. This aqueous solution was mixed with 6 mL of the dispersion, and the resulting mixture was heated at 80°C for 4 hours while stirring under a 6 W white LED lamp.

[0116] Degassed deionized water (approximately 50 mL) was added to the heated mixture to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and an aqueous solution separated from the mixture.

[0117] Next, the polymer particles contained in the mixed solution concentrated to about 8 mL were washed as follows: First, degassed deionized water (about 50 mL) was added to the concentrated mixed solution (8 mL), and the resulting mixed solution was concentrated to about 8 mL by centrifugal filtration in the same manner as in Example 1. This procedure was repeated twice.

[0118] As in Example 1, the aqueous solution separated by the nth centrifugal filtration is referred to as aqueous solution n. The tellurium concentrations in the separated aqueous solutions 1, 2, and 3 (a total of three samples) were measured by ICP-AES, as described below. The tellurium recovery rates calculated from the tellurium concentration measurements in aqueous solutions 1, 2, and 3 were as shown in Table 3. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium rate in the obtained polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual tellurium concentration and residual rate in the polymer sample are shown in Table 3.

[0119] In Example 3, a portion (approximately 10 μL) of the concentrated mixture obtained after washing the polymer particles by centrifugal filtration was diluted with degassed deionized water (approximately 5.0 mL) to prepare a sample for measuring the polymer particles. Using this sample, the average particle size and particle size polydispersity index of the polymer particles were measured using the same light scattering device as in Example 1. The results are shown in Table 4. Table 4 also shows the rate of change in the average particle size and the particle size polydispersity index of the final polymer particles (polymer particles B) after washing the polymer particles compared to the polymer particles (polymer particles A) before separation of the organotellurium groups and washing the polymer particles.

[0120] Example 4 [Synthesis of polymers by emulsion polymerization] In Example 4, a polymer was synthesized in the same manner as in Example 2. The number average molecular weight M n The molecular weight dispersity, average particle size, and particle size polydispersity index were measured. The measurement results are shown in Table 2.

[0121] [Separation of organotellurium groups from the growing ends of polymers] As the reactant soluble in water, which was the first solvent, p-mercaptobenzoic acid, which was used in Example 1, was used. This thiol (7.5 μmol) and an aqueous solution of sodium hydroxide (15 μL, 0.51 mol / L) were mixed.-1 An aqueous solution was prepared by dissolving 7.5 μmol of PEG-100 in 2.0 mL of degassed deionized water. This aqueous solution was mixed with 6 mL of the dispersion, and the resulting mixture was heated at 80°C for 4 hours while stirring under a 6 W white LED lamp.

[0122] Degassed methanol (approximately 50 mL) was added to the heated mixture to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and a methanol solution separated from the mixture.

[0123] Next, the polymer particles contained in the mixed solution concentrated to about 8 mL were washed as follows: First, degassed methanol (about 50 mL) was added to the concentrated mixed solution (8 mL), and the resulting mixed solution was concentrated to about 8 mL by centrifugal filtration in the same manner as in Example 1. This procedure was repeated twice.

[0124] As in Example 1, the methanol solution separated by the nth centrifugal filtration is referred to as methanol solution n. The tellurium concentrations in the separated methanol solutions 1, 2, and 3 (a total of three samples) were measured by ICP-AES, as described below. The tellurium recovery rates calculated from the tellurium concentration measurements in methanol solutions 1, 2, and 3 were as shown in Table 3. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium percentage in the obtained polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual tellurium concentration and percentage in the polymer sample are shown in Table 3.

[0125] Example 5 [Synthesis of polymers by emulsion polymerization] In a nitrogen atmosphere, a polymerization inhibitor (1.6 mg, 5.0 μmol) and CTAB (260 mg, 4.3 mass % relative to water) were added to a glass tube. The organotellurium compound represented by the structural formula (14) used in Example 2 was used as the polymerization inhibitor.

[0126] In the glass tube, add degassed deionized water (6.0 mL) and an aqueous solution of sodium hydroxide (10 μL, 0.51 mol L). -1 Further addition of styrene (0.58 mL, 5.0 mmol) as a monomer resulted in a homogeneous solution. This solution was mixed with styrene (0.58 mL, 5.0 mmol) as a monomer to obtain a mixture. The resulting mixture was heated at 80°C for 4 hours while stirring under a 6 W white light-emitting diode (LED) lamp. After that, a small amount (approximately 100 μL) of the reaction mixture was removed, and the organic matter was extracted from the removed reaction mixture with deuterated chloroform. After separating and drying the deuterated chloroform phase, 1 The degree of monomer conversion was measured by H NMR. The degree of styrene conversion reached 93% after 4 hours. The final reaction mixture was a dispersion of polymer particles in water (corresponding to the first solvent).

[0127] A small amount (about 100 μL) of the dispersion was taken out from the above dispersion, and the polymer was extracted from the reaction mixture with chloroform. The number average molecular weight M n The number average molecular weight M and the polydispersity of the molecular weight were analyzed by SEC in the same manner as in Example 1. Another portion (about 10 μL) of this dispersion was diluted with deionized water (about 5.0 mL) to prepare a sample for measuring the polymer particles. This sample was used to measure the average particle size and the polydispersity index of the polymer particles using the same light scattering device as in Example 1. For the polymer synthesized in Example 5, the number average molecular weight M n The molecular weight dispersity, average particle size, and particle size polydispersity index are shown in Table 2.

[0128] [Separation of organotellurium groups from the growing ends of polymers] 2-Aminoethanethiol (HSCH2CH2NH2) was used as the first solvent, a water-soluble reactant. This 2-aminoethanethiol (7.5 μmol) was dissolved in 2.0 mL of degassed deionized water to prepare an aqueous solution. This aqueous solution was mixed with 6 mL of the above dispersion, and the resulting mixture was heated at 80°C for 4 hours while stirring under a 6W white LED lamp.

[0129] Degassed methanol (approximately 50 mL) was added to the heated mixture to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and a methanol solution separated from the mixture.

[0130] Next, the polymer particles contained in the mixture concentrated to about 8 mL were washed as follows: Degassed methanol (about 50 mL) was added to the concentrated mixture (8 mL), and the resulting mixture was concentrated to about 8 mL by centrifugal filtration in the same manner as in Example 1. This procedure was repeated twice.

[0131] Example 6 [Synthesis of polymers by emulsion polymerization] Under a nitrogen atmosphere, a polymerization inhibitor (1.5 mg, 5.0 μmol) and polyoxyethylene (20) oleyl ether (Brij98, 120 mg, 2% by mass relative to water) were added to a glass tube. The organotellurium compound represented by the structural formula (13) used in Example 1 was used as the polymerization inhibitor.

[0132] In the glass tube, add degassed deionized water (6.0 mL) and an aqueous solution of sodium hydroxide (10 μL, 0.51 mol L). -1Further addition of butyl acrylate (0.69 mL, 5 mmol) as a monomer resulted in a homogeneous solution. This solution was mixed with butyl acrylate (0.69 mL, 5 mmol) as a monomer to obtain a mixture. The resulting mixture was heated at 65°C for 12 hours while stirring under a 3W white light-emitting diode (LED) lamp. A small amount (approximately 100 μL) of the reaction mixture was then removed, and the organic matter was extracted from the removed reaction mixture with deuterated chloroform. The deuterated chloroform phase was separated and dried, and then the mixture was thawed. 1 The degree of monomer conversion was measured by H NMR. The degree of conversion of butyl acrylate reached 81% after 12 hours. The final reaction mixture was a dispersion of polymer particles in water (corresponding to the first solvent).

[0133] A small amount (about 100 μL) of the dispersion was taken out from the above dispersion, and the polymer was extracted from the reaction mixture with chloroform. The number average molecular weight M n The number average molecular weight M of the polymer synthesized in Example 6 was measured using SEC. The number average molecular weight M of the polymer synthesized in Example 6 was measured using a light scattering device similar to that used in Example 1 ... n The molecular weight dispersity, average particle size, and particle size polydispersity index are shown in Table 2.

[0134] [Separation of organotellurium groups from the growing ends of polymers] p-Mercaptobenzoic acid, which was used in Example 1, was used as the reactant soluble in water, the first solvent. This thiol (7.5 μmol) was dissolved in 2.0 mL of degassed deionized water to obtain an aqueous solution, which was then added to 6 mL of the dispersion to obtain a mixed solution. Next, an aqueous sodium hydroxide solution (15 μL, 0.51 mol L) was added to this mixed solution. -1 The resulting mixture was heated at 80° C. for 4 hours with stirring under a 6 W white LED lamp.

[0135] Degassed deionized water (approximately 52 mL) was added to the heated mixture to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and an aqueous solution separated from the mixture.

[0136] Next, the polymer particles contained in the mixed solution concentrated to about 8 mL were washed as follows: First, degassed deionized water (about 52 mL) was added to the concentrated mixed solution (8 mL), and the resulting mixed solution was concentrated to about 8 mL by centrifugal filtration in the same manner as in Example 1. This procedure was repeated twice.

[0137] As in Example 1, the aqueous solution separated by the nth centrifugal filtration is referred to as aqueous solution n. The tellurium concentrations in the separated aqueous solutions 1, 2, and 3 (a total of three samples) were measured by ICP-AES, as described below. The tellurium recovery rates calculated from the tellurium concentration measurements in aqueous solutions 1, 2, and 3 were as shown in Table 3. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium rate in the obtained polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual tellurium concentration and residual rate in the polymer sample are shown in Table 3.

[0138] Example 7 [Synthesis of polymers by emulsion polymerization] In a nitrogen atmosphere, a polymerization inhibitor (1.6 mg, 5.0 μmol) and Brij 98 (120 mg, 2% by mass based on water) were added to a glass tube. The organotellurium compound represented by the structural formula (14) used in Examples 2 to 4 was used as the polymerization inhibitor.

[0139] In the glass tube, add degassed deionized water (6.0 mL) and an aqueous solution of sodium hydroxide (10 μL, 0.51 mol L). -1, 5.0 mol) was further added to obtain a homogeneous solution. This solution was mixed with butyl acrylate (0.69 mL, 5 mmol) as a monomer to obtain a mixture. The resulting mixture was heated at 65°C for 12 hours while stirring under a 3W white light-emitting diode (LED) lamp. After that, a small amount (approximately 100 μL) of the reaction mixture was taken out, and the organic matter was extracted from the reaction mixture with deuterated chloroform. After separating and drying the deuterated chloroform phase, 1 The degree of monomer conversion was measured by H NMR. The conversion rate of butyl acrylate reached 91% after 12 hours. The final reaction mixture was a dispersion of polymer particles in water (corresponding to the first solvent).

[0140] A small amount (about 100 μL) of the dispersion was taken out from the above dispersion, and the polymer was extracted from the reaction mixture with chloroform. The number average molecular weight M n The number average molecular weight M of the polymer synthesized in Example 7 was measured using SEC. The number average molecular weight M of the polymer synthesized in Example 7 was measured using a light scattering device similar to that used in Example 1 ... n The molecular weight dispersity, average particle size, and particle size polydispersity index are shown in Table 2.

[0141] [Separation of organotellurium groups from the growing ends of polymers] As the reactant soluble in water, which was the first solvent, p-mercaptobenzoic acid, which was used in Example 1, was used. This thiol (7.5 μmol) and an aqueous solution of sodium hydroxide (15 μL, 0.51 mol / L) were mixed. -1 An aqueous solution was prepared by dissolving 7.5 μmol of PEG-100 in 2.0 mL of degassed deionized water. This aqueous solution was mixed with 6 mL of the dispersion, and the resulting mixture was heated at 80°C for 4 hours while stirring under a 6 W white LED lamp.

[0142] Degassed deionized water (approximately 52 mL) was added to the heated mixture to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and an aqueous solution separated from the mixture.

[0143] Next, the polymer particles contained in the mixed solution concentrated to about 8 mL were washed as follows: First, degassed deionized water (about 52 mL) was added to the concentrated mixed solution (8 mL), and the resulting mixed solution was concentrated to about 8 mL by centrifugal filtration in the same manner as in Example 1. This procedure was repeated twice.

[0144] As in Example 1, the aqueous solution separated by the nth centrifugal filtration is referred to as aqueous solution n. The tellurium concentrations in the separated aqueous solutions 1, 2, and 3 (a total of three samples) were measured by ICP-AES, as described below. The tellurium recovery rates calculated from the tellurium concentration measurements in aqueous solutions 1, 2, and 3 were as shown in Table 3. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium rate in the obtained polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual tellurium concentration and residual rate in the polymer sample are shown in Table 3.

[0145] Example 8 [Synthesis of polymers by emulsion polymerization] A polymerization inhibitor (5.0 μmol) and CTAB (5% by mass relative to water) were added to a glass tube under a nitrogen atmosphere. An organotellurium compound represented by the following formula (15) was used as the polymerization inhibitor. The organotellurium compound represented by the following formula (15) had the most hydrophilic substituent among the polymerization inhibitors used in the examples. [ka]

[0146] In the glass tube, add degassed deionized water (6.0 mL) and an aqueous solution of sodium hydroxide (10 μL, 0.51 mol L). -1 Further addition of styrene (0.58 mL, 5.0 mmol) as a monomer resulted in a homogeneous solution. This solution was mixed with styrene (0.58 mL, 5.0 mmol) as a monomer to obtain a mixture. The resulting mixture was heated at 80°C for 5 hours while stirring under a 6 W white light-emitting diode (LED) lamp. After that, a small amount (approximately 100 μL) of the reaction mixture was removed, and the organic matter was extracted from the removed reaction mixture with deuterated chloroform. After separating and drying the deuterated chloroform phase, 1 The degree of monomer conversion was measured by H NMR. The degree of styrene conversion reached 98% after 5 hours. The final reaction mixture was a dispersion of polymer particles in water (corresponding to the first solvent).

[0147] A small amount (about 100 μL) of the dispersion was taken out from the above dispersion, and the polymer was extracted from the reaction mixture with chloroform. The number average molecular weight M n The number average molecular weight M and the polydispersity of the molecular weight were analyzed by SEC in the same manner as in Example 1. Another portion (about 10 μL) of this dispersion was diluted with deionized water (about 5.0 mL) to prepare a sample for measuring the polymer particles. This sample was used to measure the average particle size and the polydispersity index of the polymer particles using the same light scattering device as in Example 1. For the polymer synthesized in Example 2, the number average molecular weight M n The molecular weight dispersity, average particle size, and particle size polydispersity index are shown in Table 2.

[0148] [Separation of organotellurium groups from the growing ends of polymers] As the reactant soluble in water, which was the first solvent, p-mercaptobenzoic acid, which was used in Example 1, was used. This thiol (7.5 μmol) and an aqueous solution of sodium hydroxide (15 μL, 0.51 mol / L) were mixed. -1An aqueous solution was prepared by dissolving 7.5 μmol of PEG-100 in 2.0 mL of degassed deionized water. This aqueous solution was mixed with 6 mL of the dispersion, and the resulting mixture was heated at 80°C for 4 hours while stirring under a 6 W white LED lamp.

[0149] Degassed deionized water (approximately 52 mL) was added to the heated mixture to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and an aqueous solution separated from the mixture.

[0150] Next, the polymer particles contained in the mixture concentrated to about 8 mL were washed. Specifically, degassed deionized water (about 52 mL) was added to the concentrated mixture (8 mL), and the resulting mixture was concentrated to about 8 mL by centrifugal filtration in the same manner as in Example 1. This procedure was repeated twice.

[0151] As in Example 1, the aqueous solution separated by the nth centrifugal filtration is referred to as aqueous solution n. The tellurium concentrations in the separated aqueous solutions 1, 2, and 3 (a total of three samples) were measured by ICP-AES, as described below. The tellurium recovery rates calculated from the tellurium concentration measurements in aqueous solutions 1, 2, and 3 were as shown in Table 3. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium rate in the obtained polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual tellurium concentration and residual rate in the polymer sample are shown in Table 3.

[0152] Example 9 [Synthesis of polymers by emulsion polymerization] In Example 9, the heat treatment time during polymerization was changed from 5 hours to 3 hours, but otherwise the polymer was synthesized in the same manner as in Example 8. The degree of styrene conversion reached 95% after 3 hours. The number average molecular weight M nThe molecular weight dispersity, average particle size, and particle size polydispersity index were measured. The measurement results are shown in Table 2.

[0153] [Separation of organotellurium groups from the growing ends of polymers] 2-Aminoethanethiol (HSCH2CH2NH2) was used as the first solvent, a water-soluble reactant. This 2-aminoethanethiol (7.5 μmol) was dissolved in 2.0 mL of degassed deionized water to prepare an aqueous solution. This aqueous solution was mixed with 6 mL of the above dispersion, and the resulting mixture was heated at 80°C for 4 hours while stirring under a 6W white LED lamp.

[0154] Degassed deionized water (approximately 52 mL) was added to the heated mixture to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and an aqueous solution separated from the mixture.

[0155] Next, the polymer particles contained in the mixture concentrated to about 8 mL were washed. Specifically, degassed deionized water (about 52 mL) was added to the concentrated mixture (8 mL), and the resulting mixture was concentrated to about 8 mL by centrifugal filtration in the same manner as in Example 1. This procedure was repeated twice.

[0156] As in Example 1, the aqueous solution separated by the nth centrifugal filtration is referred to as aqueous solution n. The tellurium concentrations in the separated aqueous solutions 1, 2, and 3 (a total of three samples) were measured by ICP-AES, as described below. The tellurium recovery rates calculated from the tellurium concentration measurements in aqueous solutions 1, 2, and 3 were as shown in Table 3. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium rate in the obtained polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual tellurium concentration and residual rate in the polymer sample are shown in Table 3.

[0157] Example 10 [Synthesis of polymers by emulsion polymerization] In Example 10, a polymer was synthesized in the same manner as in Example 6. That is, poly(n-butyl acrylate) was synthesized, and a dispersion liquid in which particles of this polymer were dispersed in water (corresponding to the first solvent) was obtained.

[0158] [Separation of organotellurium groups from the growing ends of polymers] As in Example 6, p-mercaptobenzoic acid was used as the first solvent, a water-soluble reactant. This thiol (7.5 μmol) was dissolved in 2.0 mL of degassed deionized water to obtain an aqueous solution, which was then added to 6 mL of the dispersion to obtain a mixed solution. Next, an aqueous solution of sodium hydroxide (15 μL, 0.51 mol L) was added to this mixed solution. -1 The resulting mixture was heated at 80° C. for 4 hours with stirring under a 6 W white LED lamp.

[0159] After heating, a mixed solvent (approximately 52 mL) of degassed deionized water and methanol in a water:methanol ratio of 1:1 (volume ratio) was added to the heated mixture to make a total volume of 60 mL. The resulting mixture was centrifuged in the same manner as in Example 1. This concentrated the mixture to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and a solution separated from the mixture. Note that the filter for centrifugal filtration became clogged during this first filtration. This is believed to be due to the dissolution of poly(n-butyl acrylate) in the methanol. Therefore, in Example 10, no subsequent cleaning was performed. The tellurium concentration in the solution was measured by ICP-AES, as described below, using the concentrated mixture and solution containing polymer particles obtained by this first filtration. The tellurium recovery rate was as shown in Table 3. The concentrated mixture was freeze-dried to obtain a polymer sample. The tellurium residual rate in the resulting polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual concentrations and percentages of tellurium in the polymer samples are shown in Table 3.

[0160] Example 11 [Synthesis of polymers by emulsion polymerization] In Example 11, a polymer was synthesized in the same manner as in Example 6. That is, poly(n-butyl acrylate) was synthesized, and a dispersion liquid in which particles of this polymer were dispersed in water (corresponding to the first solvent) was obtained.

[0161] [Separation of organotellurium groups from the growing ends of polymers] As in Example 6, p-mercaptobenzoic acid was used as the first solvent, a water-soluble reactant. This thiol (7.5 μmol) was dissolved in 2.0 mL of degassed deionized water to obtain an aqueous solution, which was then added to 6 mL of the dispersion to obtain a mixed solution. Next, an aqueous solution of sodium hydroxide (15 μL, 0.51 mol L) was added to this mixed solution. -1 The resulting mixture was heated at 80° C. for 4 hours with stirring under a 6 W white LED lamp.

[0162] To the heated mixture, a mixed solvent (approximately 52 mL) of degassed deionized water and methanol in a water:methanol ratio of 9:1 (volume ratio) was added to make a total volume of 60 mL, and the resulting mixture was centrifuged in the same manner as in Example 1. As a result, the mixture was concentrated to approximately 8 mL. That is, the centrifugal filtration yielded a concentrated mixture containing polymer particles and a solution separated from this mixture.

[0163] Next, the polymer particles contained in the mixed solution concentrated to about 8 mL were washed as follows: First, the above-mentioned mixed solvent (about 52 mL) of water:methanol = 9:1 (volume ratio) was added to the concentrated mixed solution (8 mL), and the resulting mixed solution was concentrated to about 8 mL by centrifugal filtration similar to Example 1. This procedure was repeated twice.

[0164] As in Example 1, the solution separated by the nth centrifugal filtration is referred to as Solution n. The tellurium concentrations in the separated Solutions 1, 2, and 3 (a total of three samples) were measured by ICP-AES, as described below. The tellurium recovery rates calculated from the tellurium concentration measurements in Solutions 1, 2, and 3 were as shown in Table 3. The final concentrated mixture was freeze-dried to obtain a polymer sample. The residual tellurium rate in the obtained polymer sample was calculated using a theoretical initial tellurium concentration of 1,280 ppm. The residual tellurium concentration and residual rate in the polymer sample are shown in Table 3.

[0165] (Measurement of tellurium by ICP-AES) [Cleaning the sample container] For sample preparation for ICP-AES analysis, containers made of polytetrafluoroethylene (PTFE) or copolymers of perfluorovinylpropyl ether (PFA) were used. These containers were previously filled with 3 mol L of a liquid detergent solution, Scat®. -1 After immersing each in a hydrochloric acid solution for one day, they were finally washed with Milli-Q water and stored in a sealable plastic bag.

[0166] To prepare samples for tellurium concentration measurement, the target samples were heated and decomposed using nitric acid and hydrogen peroxide. They were then dried and dissolved in an accurately weighed amount of aqueous nitric acid. The characteristic tellurium emission intensities at 214 nm and 238 nm were measured using an ICP-AES measurement device (Spectro Blue, manufactured by Spectro Corporation), and the concentration in the samples was determined using a calibration curve prepared using a tellurium standard solution.

[0167] [Preparation of sample for tellurium concentration measurement from filtrate] The filtrate (aqueous or methanolic solution) obtained by centrifugal filtration of the polymer particle dispersion was collected in a PFA container and its mass was precisely measured. The amount of filtrate collected was determined based on the expected tellurium concentration in the sample. For example, if a tellurium concentration of approximately 10 ppm was expected, 10 mL of filtrate was collected. The PFA container was placed on a hot plate and the filtrate was dried at 100 °C for 6 hours. After cooling to room temperature, concentrated nitric acid (2.0 mL) was added and the container was heated again at 100 °C for 30 minutes to completely dissolve the solids. The solution was then rinsed with concentrated nitric acid (3.0 mL) and quantitatively transferred to a PTFE cylindrical container for decomposition, to which 30% hydrogen peroxide (0.5 mL) was added. The cylindrical container was sealed and heated at 200 °C or higher for 2 hours using a microwave heating device (Speed ​​Wave MWS-3, manufactured by Analytik Jena) to completely decompose the sample. After cooling to room temperature, the sample solution was quantitatively transferred to a PFA container by rinsing with Milli-Q water and then dried on a hot plate at 160 °C for 6 hours. An accurately weighed amount of aqueous nitric acid solution (10 mL, 3% solution) was added to the solid, and the solid was heated at 80 °C overnight to completely dissolve it. If any solid remained, it was again subjected to microwave heating treatment using nitric acid and hydrogen peroxide. The solution was cooled to room temperature and analyzed by ICP-AES.

[0168] [Preparation of samples for tellurium concentration measurement from polymer samples] The dried polymer sample was directly placed in a PTFE cylindrical container and its mass was measured. The amount of polymer to be collected was determined based on the expected tellurium concentration in the sample. For example, if the tellurium concentration was expected to be approximately 10 ppm, approximately 0.1 g of polymer was collected. Concentrated nitric acid (5.0 mL) and 30% by weight hydrogen peroxide solution (0.5 mL) were added, and the cylindrical container was sealed. Complete decomposition and dissolution were achieved by heating for 4 hours using the same treatment as above.

[0169] [Calculation of tellurium concentration by ICP-AES measurement] The characteristic luminescence intensity of tellurium at 214 nm and 238 nm was measured using an ICP-AES measuring device (Spectro Blue, manufactured by Spectro Corporation), and the concentration in the sample was determined using a calibration curve prepared using a tellurium standard solution.

[0170] [Results of Examples 1 to 11] [Table 2]

[0171] [Table 3]

[0172] [Table 4]

[0173] In Examples 1 to 11, a dispersion was used in which polymer particles composed of a polymer containing organotellurium groups at its growing terminals, synthesized by emulsion polymerization using an organotellurium compound as a polymerization inhibitor, were dispersed in water as the first solvent. In Examples 1 to 11, this dispersion was mixed with a water-soluble thiol, and the resulting mixture was heated at 80°C for 4 hours. Then, the mixture was centrifuged to separate a concentrated dispersion containing polymer particles and a filtrate solution. As shown in Table 3, in Examples 1 to 11, tellurium was contained in the filtrate obtained by centrifugal filtration. This tellurium is believed to be derived from the organotellurium groups contained in the growing terminals of the polymer. In other words, the method performed in Examples 1 to 11 appears to have successfully separated the organotellurium groups from polymer particles composed of a polymer containing organotellurium groups at its growing terminals, synthesized by emulsion polymerization. Furthermore, as confirmed in Examples 2 and 3, the polymer maintained its particle shape even after the organotellurium groups were separated. These results demonstrate that the method for producing polymer particles of the present invention makes it possible to separate organotellurium groups from polymer particles made of a polymer having organotellurium groups bonded to its growing ends while maintaining the particle shape, thereby obtaining polymer particles with a reduced amount of organotellurium groups.

[0174] In Examples 1 and 4, methanol was used as the second solvent for separating the polymer particles from the solution containing the organotellurium compound formed by the reaction of the organotellurium group attached to the growing end of the polymer forming the polymer particles with thiol, and for washing the polymer particles. The tellurium recovery rate in Examples 1 and 4, in which methanol was used, was higher than that in Examples 2 and 3, in which only water was used. These results demonstrate that when the synthesized polymer is polystyrene, tellurium can be recovered at a higher recovery rate by using alcohol during separation and washing than when water is used.

[0175] The organotellurium compound represented by formula (15) used as a polymerization inhibitor in Examples 8 and 9 has high water solubility due to the hydroxyl group at the terminal ethylene oxide bonded to the tellurium. Therefore, UV-VIS analysis confirmed that the ditelluride generated from this organotellurium compound was also water soluble. In Example 9, 2-aminoethanethiol (HSCH2CH2NH2) was used as the reactant, and the reduction product (Product 2) was converted almost quantitatively to ditelluride, which was then separated from the polystyrene. When water was used as the solvent, the proportion of tellurium transferred to the aqueous phase in each washing step was measured by ICP-AES, and the results were better than those in Examples 1 to 5 and 8. Furthermore, in Example 9, the remaining tellurium content in the final polymer sample was 34.6 ppm (2.7%). These results demonstrate that the method used in Example 9 enables highly efficient separation and recovery of tellurium.

[0176] In Examples 6, 7, 10, and 11, poly(n-butyl acrylate), a highly polar polymer, was used as the polymer, and organotellurium was separated and recovered from this polymer. In Examples 6 and 7, water was used as the solvent for washing. In contrast, in Examples 10 and 11, a mixed solvent of water and methanol was used for washing. As can be seen from the results shown in Table 3, the residual tellurium concentrations in the polymer samples in Examples 10 and 11 were lower than the residual tellurium concentrations in the polymer samples in Examples 6 and 7. This demonstrates that by using a mixed solvent of water and methanol for washing, this method exhibits good versatility for use with various polymer samples. [Industrial Applicability]

[0177] The polymer particles obtained by the method for producing polymer particles of the present invention have an extremely low tellurium concentration, and the particle shape, such as particle size, can be highly controlled. Therefore, the polymer particles obtained by the present invention can be used in a variety of applications, including applications with high added value in biomaterials, etc.

Claims

1. (i) a step of mixing polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at its growing ends, synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent, a dispersion A of the polymer particles A containing the polymer particles A and a first solvent for dispersing the polymer particles A, with a reactant soluble in the first solvent, and removing the organotellurium groups from the growing ends of the polymer to obtain a mixed solution containing a second organotellurium compound produced by a reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A; (ii) separating the mixed solution into the polymer particles B and a solution in which the second organotellurium compound is dissolved; Including, the reacting agent is a reducing agent having, as a first substituent that reacts with the organotellurium group, at least one selected from the group consisting of a thiol group, a tellurol group, and a selenol group; Method for producing polymer particles.

2. In the step (i), the polymer particles B are obtained by removing the organotellurium groups from the growing ends of the polymer constituting the polymer particles A while substantially maintaining the shape of the polymer particles A. The method for producing the polymer particles according to claim 1 .

3. the reactant further comprises at least one second substituent having an affinity for the first solvent; The method for producing the polymer particles according to claim 1 or 2.

4. the first solvent comprises water; the second substituent is at least one selected from the group consisting of a carboxy group and a salt thereof, an amino group and a salt thereof, an amide group, a hydroxyl group, a sulfo group and a salt thereof, and an ether group; The method for producing the polymer particles according to claim 3 .

5. The tellurium concentration of the polymer particles B is 1000 ppm by mass or less, and / or the tellurium concentration of the polymer particles B is 70 mass% or less relative to the tellurium concentration of the polymer particles A; The method for producing polymer particles according to any one of claims 1 to 4.

6. The method further includes a step (iii) of washing the polymer particles B obtained in the step (ii) with a second solvent, In the step (iii), the second organotellurium compound is further separated from the polymer particles B. The method for producing polymer particles according to any one of claims 1 to 5.

7. the second solvent has an affinity for the first solvent and does not dissolve the polymer particles B; The method for producing polymer particles according to claim 6 .

8. the first solvent comprises water; the second solvent is infinitely dilutable with water and does not dissolve the polymer particles B; The method for producing polymer particles according to claim 6 or 7.

9. the second solvent is one solvent selected from the group consisting of water, alcohols, amides, ketones, and alkyl sulfoxides, or a mixed solvent of two or more solvents; The method for producing polymer particles according to claim 8 .

10. In the step (ii), the mixed solution is separated into the polymer particles B and a solution in which the second organotellurium compound is dissolved by a solid-liquid separation method. The method for producing polymer particles according to any one of claims 1 to 9.

11. (i) a step of mixing polymer particles A made of a polymer with a controlled structure containing organotellurium groups at its growing ends, a dispersion A of the polymer particles A containing the polymer particles A and a solvent for dispersing the polymer particles A, with a reactant soluble in the solvent, and removing the organotellurium groups from the growing ends of the polymer to obtain a mixed solution containing an organotellurium compound produced by the reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A; (ii) separating the mixed solution into the polymer particles B and a solution in which the organotellurium compound is dissolved; Including, the reactant is a reducing agent having at least one selected from the group consisting of a thiol group, a tellurol group, and a selenol group; Method for producing polymer particles.

12. a step of mixing polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at a growing end, the polymer particles A being synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent, a dispersion A of the polymer particles A containing a solvent for dispersing the polymer particles A, and a reactant soluble in the solvent to remove the organotellurium groups from the growing end of the polymer, thereby obtaining a mixed solution containing a second organotellurium compound produced by a reaction between the reactant and the organotellurium groups, and polymer particles B in which the organotellurium groups have been reduced in number compared to the polymer particles A, the reactant is a reducing agent having at least one selected from the group consisting of a thiol group, a tellurol group, and a selenol group; A method for obtaining a mixture containing polymer particles and an organotellurium compound.

13. (I) a step of mixing polymer particles A composed of a polymer with a controlled structure containing organotellurium groups at its growing terminals, synthesized by emulsion polymerization using a first organotellurium compound as a polymerization control agent, a dispersion A of the polymer particles A containing a solvent for dispersing the polymer particles A, and a reactant soluble in the solvent to remove the organotellurium groups from the growing terminals of the polymer, thereby obtaining a mixed solution containing a second organotellurium compound produced by a reaction between the reactant and the organotellurium groups, and polymer particles B in which the amount of the organotellurium groups has been reduced compared to the polymer particles A; (II) separating the mixture into the polymer particles B and a solution in which the second organotellurium compound is dissolved; and (III) recovering tellurium from the solution containing the second organotellurium compound obtained in step (II); Including, the reactant is a reducing agent having at least one selected from the group consisting of a thiol group, a tellurol group, and a selenol group; Tellurium recovery methods.

14. A dispersion of polymer particles, comprising: the polymer constituting the polymer particles has a molecular weight dispersity of 1 or more and 2 or less when the polymer is a linear polymer, and a molecular weight dispersity of 1 or more and 4 or less when the polymer is a branched polymer; the tellurium concentration in the polymer particles is greater than 0 ppm by mass and 1000 ppm by mass or less; The particle size polydispersity index of the polymer particles is 0.7 or less. Dispersion of polymer particles.

15. The average particle size of the polymer particles is 1 nm or more and 100 μm or less. A dispersion of polymer particles according to claim 14.

Images