Polymer manufacturing method

Abstract

To provide a method for producing a polymer which can obtain a polymer that has a small content of a volatile component containing a solvent and is sufficiently reduced in odor.SOLUTION: A polymer is produced by a method including a first step of treating a mixed liquid containing a polymer and a solvent using a thin film evaporator at a temperature of 80-130°C and a pressure of 40-100 Torr, reducing an amount of a volatile component in the mixed liquid, and thereby obtaining a first concentrated liquid containing the polymer, and a second step of treating the first concentrated liquid using a thin film evaporator or a flash evaporator at a temperature of 80-130°C and a pressure lower than the pressure at the time of distillation in the first step, reducing an amount of the volatile component in the first concentrated liquid, and thereby obtaining a second concentrated liquid containing a polymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polymer, and more particularly to a technique for purifying a mixed liquid containing a polymer and a solvent to recover the polymer. [Background technology]

[0002] Various methods have been proposed for removing a solvent from a mixture containing a polymer and the solvent to obtain a highly pure polymer (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses that a mixture containing a styrene-acrylic copolymer and volatile components is purified using a single-screw thin-film evaporator at a temperature of 150 to 210°C to remove the volatile components and obtain a styrene-acrylic copolymer. Patent Document 2 also discloses that a mixture containing an acrylic block copolymer and an organic solvent is heated to 100 to 200°C, supplied to a thin-film evaporator while flashing, and distilled at a pressure of 10 to 300 Torr during distillation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-41123 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-352744 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have conducted studies and found that when a mixed liquid containing a polymer and a solvent is purified using the method described in Patent Document 1, the distillation temperature is too high, which can cause deterioration of the polymer and lead to a strong odor of the polymer.

[0005] Furthermore, in the case of the method described in Patent Document 2, depending on the properties of the mixed liquid, foaming may occur when the mixed liquid is supplied to the thin-film evaporator while being flashed, which may result in the mixed liquid being entrained in the vacuum system. On the other hand, if a temperature and pressure that do not cause foaming are selected as purification conditions, there is a concern that the solvent may not be sufficiently removed.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a polymer by which a polymer having a low content of volatile components, including solvents, and having a sufficiently reduced odor can be obtained. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems and have focused on performing a purification procedure twice under different conditions. Based on this finding, the present invention has been completed. Specifically, the present invention provides the following means.

[0008] [1] A method for producing a polymer, comprising: a first step of treating a mixed liquid containing a polymer and a solvent using a thin-film evaporator at a temperature of 80 to 130°C and a pressure of 40 to 100 Torr to reduce the amount of volatile components in the mixed liquid, thereby obtaining a first concentrated liquid containing the polymer; and a second step of treating the first concentrated liquid using a thin-film evaporator or a flash evaporator at a temperature of 80 to 130°C and a pressure lower than the pressure during distillation in the first step, thereby reducing the amount of volatile components in the first concentrated liquid, thereby obtaining a second concentrated liquid containing the polymer.

[0009] [2] The method for producing a polymer according to [1] above, wherein in the second step, the first concentrated liquid is treated at a pressure of 30 Torr or less. [3] The method for producing a polymer according to [1] or [2] above, wherein the polymer is a (meth)acrylic polymer. [4] The method for producing a polymer according to the above [3], wherein the (meth)acrylic polymer is a block copolymer having two or more polymer blocks. [5] The method for producing a polymer according to any one of the above [1] to [4], wherein the viscosity of the mixture is 500 to 100,000 mP·s at 25°C. [6] The method for producing a polymer according to any one of the above [1] to [5], wherein the treatment temperature in the first step and the treatment temperature in the second step are 100 to 130°C. [Effects of the Invention]

[0010] According to the present invention, it is possible to obtain a polymer having a low content of volatile components including solvents and having a sufficiently reduced odor. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of a schematic configuration of a distillation system in which pre-purification and post-purification are performed using a thin-film evaporator. [Figure 2] FIG. 1 is a diagram showing an example of the schematic configuration of a distillation system in which pre-purification is performed using a thin-film evaporator and post-purification is performed using a flash evaporator. DETAILED DESCRIPTION OF THE INVENTION

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

[0013] The method for producing a polymer of the present invention (hereinafter also referred to as "the present production method") is a method for producing a polymer by a method including the following first and second steps. First step: A step of treating a mixed liquid containing a polymer and a solvent (hereinafter also referred to as "raw material mixed liquid") using a thin-film evaporator at a temperature of 80 to 130°C and a pressure of 40 to 100 Torr to reduce the amount of volatile components in the raw material mixed liquid, thereby obtaining a first concentrated liquid containing the polymer. Second step: A step of treating the first concentrated liquid obtained in the first step using a thin film evaporator or a flash evaporator at a temperature of 80 to 130°C and at a pressure lower than the pressure during distillation in the first step, thereby reducing the amount of volatile components in the first concentrated liquid, thereby obtaining a second concentrated liquid containing the above-mentioned polymer. The details of this manufacturing method will be described below.

[0014] (raw material mixture) The raw material mixture used in this production method contains a polymer and a solvent. There are no particular limitations on the type of polymer contained in the raw material mixture, but vinyl polymers are preferred because of their high versatility. Among these, (meth)acrylic polymers are preferred because of their high weather resistance and ease of adjusting physical properties, and (meth)acrylic block copolymers having two or more polymer blocks are particularly preferred. When the polymer contained in the raw material mixture is a block copolymer, there are no particular limitations on the number of blocks or block structure of the block copolymer.

[0015] The polymer content in the raw material mixture is not particularly limited, but from the viewpoint of improving purification efficiency, it is preferably 65% by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more, based on the total amount of the raw material mixture. The polymer content in the raw material mixture is a value calculated by heating a sample (here, the raw material mixture) at 150°C for 1 hour and using the mass of the sample before heating (M0) and the mass of the sample after heating (M1) according to the following mathematical formula (1). Details of the calculation method follow the method described in the Examples below. Polymer content (mass%) = (M1 / M0) × 100 ... (1)

[0016] The raw material mixture contains a solvent as a volatile component (hereinafter also simply referred to as a volatile component) that volatilizes during the purification operations in Steps 1 and 2. The "volatile component" contained in the raw material mixture is a component that volatilizes more easily than the polymer contained in the raw material mixture, and is preferably liquid at room temperature (25°C).

[0017] The solvent contained in the raw material mixture is preferably an organic solvent capable of dissolving the polymer in the raw material mixture. Various solvents can be used as such an organic solvent, and examples thereof include saturated hydrocarbon compounds, aromatic compounds, ester compounds, ketone compounds, alcohol compounds, ether compounds, and nitrile compounds. The raw material mixture may contain one type of solvent or two or more types of solvents.

[0018] From the viewpoint of improving purification efficiency, the boiling point at atmospheric pressure of the solvent contained in the raw material mixture is preferably 200° C. or lower, more preferably 150° C. or lower, and even more preferably 110° C. or lower. There are no particular restrictions on the lower limit of the boiling point, but it is, for example, 50° C. or higher, preferably 55° C. or higher. When the raw material mixture contains two or more solvents, it is preferable that the boiling points of the respective solvents be within the above range.

[0019] The raw material mixture may contain only a solvent as a volatile component, or may further contain components other than the solvent. Examples of components other than the solvent include unreacted monomers and additives used in polymer synthesis. Each component contained as a volatile component in the raw material mixture is preferably a liquid organic compound having a boiling point of 260°C or less at atmospheric pressure. The boiling point of the volatile component at atmospheric pressure is more preferably 230°C or less, even more preferably 200°C or less, and even more preferably 180°C or less. When the raw material mixture contains two or more compounds as volatile components, it is preferable that the boiling points of each compound be within the above range.

[0020] The amount of volatile components contained in the raw material mixture (when components other than the solvent are contained, the total amount of the solvent and the components other than the solvent) is preferably 0.5 to 35 mass %, more preferably 1.0 to 30 mass %, and even more preferably 1.0 to 25 mass %, relative to the total amount of the raw material mixture. The amount of volatile components in the raw material mixture is a value obtained by subtracting the amount (mass %) of polymer contained in the raw material mixture from the total amount (100 mass %) of the raw material mixture. The amount (mass %) of polymer contained in the raw material mixture can be calculated using the above formula (1).

[0021] The viscosity of the raw material mixture supplied to the thin film evaporator in the first step is preferably 100 mPa·s or more, more preferably 300 mPa·s or more, even more preferably 500 mPa·s or more, even more preferably 800 mPa·s or more, and even more preferably 1,000 mPa·s or more, from the viewpoint of forming a thin film on the heated surface of the thin film evaporator and efficiently recovering the polymer. The upper limit of the viscosity of the raw material mixture is preferably 200,000 mPa·s or less, more preferably 150,000 mPa·s or less, even more preferably 100,000 mPa·s or less, and even more preferably 80,000 mPa·s or less, from the viewpoint of preventing abnormal vibrations during purification using the thin film evaporator and ensuring fluidity on the heated surface. Note that when performing the purification process, a thin film evaporator that can accommodate the viscosity of the raw material mixture is used.

[0022] A preferred range of the viscosity of the raw material mixture can be set by appropriately combining the above-mentioned upper and lower limits. The viscosity of the raw material mixture is preferably 100 to 200,000 mPa·s, more preferably 300 to 150,000 mPa·s, even more preferably 500 to 100,000 mPa·s, and still more preferably 800 to 100,000 mPa·s. In this specification, the viscosity of the raw material mixture is a value measured at 25°C using an E-type viscometer.

[0023] Examples of the raw material mixture include (1) a polymer-containing solution obtained by a solution polymerization method (i.e., a solution in which a polymer, which is a reaction product, is dissolved in the solvent used in the polymerization reaction), and (2) a polymer-containing solution in which a polymer obtained by synthesis using any polymerization method is dissolved in a solvent. Among these, when the polymer-containing solution of (1) above is used as the raw material mixture, the amounts of polymerization solvent, unreacted monomer, etc. contained in the polymer-containing solution can be sufficiently reduced, and a polymer with high purity can be obtained by a simple operation, which is industrially advantageous.

[0024] - Polymer manufacturing The polymerization method for producing the polymer contained in the raw material mixture (hereinafter also simply referred to as polymer) is not particularly limited, but a radical polymerization method is preferred because it can be applied to the polymerization of various vinyl monomers.

[0025] When producing a polymer by radical polymerization, a method of polymerizing monomers can be applied, employing a known polymerization method such as solution polymerization, suspension polymerization, emulsion polymerization, or bulk polymerization. For example, when producing a vinyl polymer by solution polymerization, a polymerization solvent and monomers are charged into a reactor, a polymerization initiator is added to the reactor, and the reaction mixture is heated as necessary to polymerize, thereby obtaining the desired vinyl polymer. The method of charging each raw material is not particularly limited, and examples thereof include batchwise initial lump-sum charging in which all raw materials are charged at once, semi-continuous charging in which at least some raw materials are continuously fed into a reactor, and continuous polymerization in which all raw materials are continuously fed and the product is continuously withdrawn from the reactor at the same time.

[0026] When the polymer contained in the raw material mixture is to be a block copolymer, examples of methods for producing the block copolymer include methods utilizing various controlled polymerization methods such as living radical polymerization, methods of coupling polymers having functional groups together, etc. Among these, living radical polymerization is preferred because it is easy to operate and can be applied to a wide range of monomers.

[0027] When producing a vinyl polymer by living radical polymerization, known polymerization methods can be used as the living radical polymerization method. Specific examples of living radical polymerization methods include living radical polymerization methods using an exchange chain mechanism, living radical polymerization methods using a bond-dissociation mechanism, and living radical polymerization methods using an atom transfer mechanism. Among these, living radical polymerization methods using an exchange chain mechanism are preferred because they can be applied to the widest range of vinyl monomers and have excellent controllability over polymerization. From the viewpoint of ease of implementation, reversible addition-fragmentation chain transfer polymerization (RAFT) is particularly preferred.

[0028] In the RAFT method, polymerization proceeds via a reversible chain transfer reaction in the presence of a polymerization control agent (RAFT agent) and a polymerization initiator. Various known RAFT agents can be used as the RAFT agent, such as dithioester compounds, xanthate compounds, trithiocarbonate compounds, and dithiocarbamate compounds. Among these, trithiocarbonate compounds are preferred because of their excellent ability to control the polymerization of (meth)acrylic acid esters. The amount of the RAFT agent used is adjusted appropriately depending on the type of monomer and RAFT agent used, etc.

[0029] In particular, polymers obtained by the RAFT method have a sulfur-containing structure derived from the RAFT agent, so if the temperature during purification is too high, the polymer is likely to deteriorate due to heat, and the polymer after purification is likely to have a strong odor. Therefore, when the present production method is applied to the purification of polymers obtained by the RAFT method, the odor is significantly reduced, making it preferable.

[0030] In radical polymerization, known radical polymerization initiators such as azo compounds, organic peroxides, and persulfates can be used as polymerization initiators. Among these, azo compounds are preferred because they are safe to handle and less likely to cause side reactions during radical polymerization. Specific examples of azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], and 2,2'-azobis(N-butyl-2-methylpropionamide). The polymerization initiator may be used alone or in combination of two or more kinds.

[0031] The amount of polymerization initiator used is not particularly limited and can be appropriately set depending on the polymerization method used. For example, in the case of the RAFT method, from the viewpoint of obtaining a polymer with a narrower molecular weight distribution, the amount of polymerization initiator used per 1 mol of RAFT agent is preferably 0.5 mol or less, more preferably 0.4 mol or less. Furthermore, from the viewpoint of stably carrying out the polymerization reaction, the lower limit of the amount of polymerization initiator used is preferably 0.01 mol or more, more preferably 0.05 mol or more, per 1 mol of RAFT agent. The amount of polymerization initiator used per 1 mol of RAFT agent is preferably 0.01 to 0.5 mol, more preferably 0.05 to 0.4 mol.

[0032] In the case of the RAFT method, the polymerization reaction may be carried out, if necessary, in the presence of a chain transfer agent such as an alkylthiol compound having 2 to 20 carbon atoms. Furthermore, if necessary, a dehydrating agent such as trimethyl orthoacetate or triethyl orthoacetate may be mixed into the reaction system.

[0033] The monomers for obtaining the polymer constituting the raw material mixture are not particularly limited. The monomers used for polymerization preferably include (meth)acrylic monomers, in that vinyl polymers can be produced relatively easily, there is a wide range of monomers to choose from, and the physical properties of the polymer can be easily adjusted.

[0034] In the above polymerization, at least one selected from the group consisting of (meth)acrylic acid alkyl ester compounds, (meth)acrylic acid aliphatic cyclic ester compounds, (meth)acrylic acid aromatic ester compounds, and compounds represented by the following formula (2) can be preferably used as the (meth)acrylic monomer. CH2=CR 1 -C(=O)O-(R 2 O) n -R 3 …(2) (In formula (2), R 1 represents a hydrogen atom or a methyl group, and R 2 represents a linear or branched alkylene group having 2 to 6 carbon atoms, and R 3represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. n represents an integer of 1 to 100.

[0035] (Meth)acrylic acid alkyl ester compounds Specific examples of the (meth)acrylic acid alkyl ester compound include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and icosyl (meth)acrylate.

[0036] Considering the fluidity of the vinyl polymer constituting the raw material mixture, it is preferable to use, among these, a (meth)acrylic acid alkyl ester compound in which the alkyl group (R) in the alkyl ester moiety (-COOR) has 1 to 20 carbon atoms. The (meth)acrylic acid alkyl ester compound constituting the polymer is more preferably a (meth)acrylic acid alkyl ester compound having an alkyl group having 2 to 20 carbon atoms, even more preferably a (meth)acrylic acid alkyl ester compound having an alkyl group having 2 to 18 carbon atoms, and even more preferably a (meth)acrylic acid alkyl ester compound having an alkyl group having 4 to 18 carbon atoms.

[0037] Aliphatic cyclic ester compounds of (meth)acrylic acid Specific examples of the aliphatic cyclic ester compounds of (meth)acrylic acid include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.

[0038] Aromatic ester compounds of (meth)acrylic acid Specific examples of aromatic ester compounds of (meth)acrylic acid include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, and 3-phenoxypropyl (meth)acrylate.

[0039] A compound represented by formula (2) Regarding the compound represented by the formula (2), when n in the formula (2) is 1, the compound represented by the formula (2) has an oxyalkylene structure such as an oxyethylene chain, an oxypropylene chain, or an oxybutylene chain. Specific examples of the compound in which n in the formula (2) is 1 (i.e., a (meth)acrylic acid alkoxyalkyl ester compound) include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, n-propoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, n-propoxypropyl (meth)acrylate, n-butoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxybutyl (meth)acrylate, n-propoxybutyl (meth)acrylate, and n-butoxybutyl (meth)acrylate.

[0040] When n in the above formula (2) is 2 or more, the compound represented by the above formula (2) has a polyoxyalkylene structure such as a polyoxyethylene chain, a polyoxypropylene chain, or a polyoxybutylene chain. When n is 2 or more, two or more R2 may be the same or different from each other. Therefore, a compound in which n in the above formula (2) is 2 or more may have different types of polyoxyalkylene structures in one molecule, such as a block structure consisting of polyoxyethylene / polyoxypropylene.

[0041] Specific examples of compounds in which n in the above formula (2) is 2 or more include polyoxyethylene (meth)acrylate, polyoxypropylene (meth)acrylate, polyoxybutylene (meth)acrylate, polyoxyethylene-polyoxypropylene (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, lauroxypolyethylene glycol (meth)acrylate, stearoxypolyethylene glycol (meth)acrylate, octoxypolyethylene glycol polypropylene glycol (meth)acrylate, nonylphenoxypolypropylene glycol (meth)acrylate, and phenoxypolyethylene glycol polypropylene glycol (meth)acrylate.

[0042] When producing a vinyl polymer with high fluidity, the (meth)acrylic monomer used is preferably a (meth)acrylic acid alkyl ester compound, more preferably a (meth)acrylic acid alkyl ester compound having an alkyl group with 2 to 18 carbon atoms, and even more preferably a (meth)acrylic acid alkyl ester compound having an alkyl group with 4 to 18 carbon atoms. Furthermore, the (meth)acrylic monomer constituting the polymer contained in the raw material mixture preferably contains at least an acrylic monomer, and more preferably contains an acrylic acid alkyl ester compound, since this allows for the production of a polymer with excellent mechanical strength and fluidity.

[0043] When producing a polymer, the amount of the (meth)acrylic acid alkyl ester compound used is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount of monomers used in the polymerization.

[0044] In producing the polymer, a vinyl monomer (hereinafter also referred to as "other monomer") other than the above-mentioned (meth)acrylic monomers and copolymerizable therewith may be further used. Examples of the other monomer include styrene compounds, maleimide compounds, amide group-containing vinyl compounds, and vinyl monomers having crosslinkable functional groups. The other monomer may be one of these, or two or more of these.

[0045] Styrene-based compounds Specific examples of styrene-based compounds include styrene, α-methylstyrene, β-methylstyrene, vinylxylene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, p-n-butylstyrene, p-isobutylstyrene, pt-butylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol, o-isopropenylphenol, o-vinylbenzoic acid, m-vinylbenzoic acid, p-vinylbenzoic acid, divinylbenzene, and vinylnaphthalene.

[0046] The amount of the styrene-based compound used is, for example, 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total amount of monomers used in the polymerization reaction.

[0047] Maleimide compounds Specific examples of the maleimide compound include maleimide and N-substituted maleimide compounds. Examples of the N-substituted maleimide compound include N-alkyl-substituted maleimide compounds such as N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N-pentylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, and N-stearylmaleimide; N-cyclopentylmaleimide; and N-cyclopentylmaleimide. N-cycloalkyl-substituted maleimide compounds such as dicyclohexylmaleimide; N-aryl-substituted maleimide compounds such as N-phenylmaleimide, N-(4-hydroxyphenyl)maleimide, N-(4-acetylphenyl)maleimide, N-(4-methoxyphenyl)maleimide, N-(4-ethoxyphenyl)maleimide, N-(4-chlorophenyl)maleimide, and N-(4-bromophenyl)maleimide; and N-aralkyl-substituted maleimide compounds such as N-benzylmaleimide.

[0048] The amount of the maleimide compound used is, for example, 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total amount of monomers used in the polymerization reaction.

[0049] Amide group-containing vinyl compounds Specific examples of amide group-containing vinyl compounds include (meth)acrylamide, (meth)acrylamide derivatives, and N-vinylamide monomers. Specific examples of (meth)acrylamide derivatives include tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and (meth)acryloylmorpholine. Specific examples of N-vinylamide monomers include N-vinylacetamide, N-vinylformamide, and N-vinylisobutylamide.

[0050] The amount of the amide group-containing vinyl compound used is, for example, 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, based on the total amount of monomers used in the polymerization reaction.

[0051] · Vinyl monomers with crosslinkable functional groups Examples of crosslinkable functional groups include crosslinkable silyl groups, silanol groups, carboxyl groups, hydroxyl groups, epoxy groups, oxazoline groups, isocyanate groups, and polymerizable unsaturated groups. Examples of crosslinkable silyl groups include alkoxysilyl groups and halogenosilyl groups. Among these, alkoxysilyl groups are preferred in terms of ease of control of reactivity, and examples thereof include trimethoxysilyl groups, methyldimethoxysilyl groups, dimethylmethoxysilyl groups, triethoxysilyl groups, methyldiethoxysilyl groups, and dimethylethoxysilyl groups.

[0052] Examples of vinyl monomers having a crosslinkable functional group include crosslinkable silyl group-containing vinyl compounds, unsaturated carboxylic acids, unsaturated carboxylic acid anhydrides, hydroxy group-containing vinyl compounds, epoxy group-containing vinyl compounds, primary or secondary amino group-containing vinyl compounds, oxazoline group-containing vinyl compounds, and isocyanate group-containing vinyl compounds.

[0053] Examples of crosslinkable silyl group-containing vinyl compounds include vinyl silanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinyldimethylmethoxysilane; alkoxysilyl group-containing (meth)acrylic acid esters such as trimethoxysilylpropyl (meth)acrylate, triethoxysilylpropyl (meth)acrylate, methyldimethoxysilylpropyl (meth)acrylate, and dimethylmethoxysilylpropyl (meth)acrylate; alkoxysilyl group-containing vinyl ethers such as trimethoxysilylpropyl vinyl ether; and alkoxysilyl group-containing vinyl esters such as vinyl trimethoxysilylundecanoate. Crosslinkable silyl group-containing vinyl compounds form crosslinked structures by dehydration condensation between crosslinkable silyl groups, making them suitable for efficient polymerization reactions during polymer production and subsequent crosslinking reactions.

[0054] Examples of unsaturated carboxylic acids include (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamic acid, and monoalkyl esters of unsaturated dicarboxylic acids (monoalkyl esters of maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.). Examples of unsaturated carboxylic acid anhydrides include maleic anhydride, itaconic anhydride, citraconic anhydride, etc.

[0055] Examples of the hydroxy group-containing vinyl compound include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, mono(meth)acrylic acid esters of polyalkylene glycols (e.g., polyethylene glycol, polypropylene glycol, etc.); styrene compounds such as o-hydroxystyrene, m-hydroxystyrene, and p-hydroxystyrene; maleimide compounds such as N-(4-hydroxyphenyl)maleimide; and the like. Among the compounds represented by the above formula (2), R 3The compound in which is a hydrogen atom is also a vinyl monomer having a crosslinkable functional group.

[0056] Examples of the epoxy group-containing vinyl compound include glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and 3,4-epoxycyclohexylmethyl (meth)acrylate.

[0057] The amount of the vinyl monomer having a crosslinkable functional group used is not particularly limited, but from the viewpoint of obtaining a vinyl polymer having excellent mechanical strength, it can be, for example, 0.01% by mass or more, and preferably 0.5% by mass or more, based on the total amount of monomers used in the polymerization reaction. The upper limit of the amount of the vinyl monomer having a crosslinkable functional group used is, for example, 40% by mass or less, and preferably 30% by mass or less, based on the total amount of monomers used in the polymerization reaction, from the viewpoint of ensuring the flexibility of the resulting vinyl polymer.

[0058] When a block copolymer having polymer block (A) and polymer block (B) is produced by the RAFT method as the polymer constituting the raw material mixture, a polymer (hereinafter also referred to as "polymer (a)") constituting polymer block (A) and having a thiocarbonylthio group may be used as the raw material together with the monomer constituting polymer block (B). By using a monofunctional RAFT agent to prepare polymer (a), an (A)-(B) diblock copolymer consisting of polymer block (A) / polymer block (B) can be obtained. By using a bifunctional RAFT agent to prepare polymer (a), an (A)-(B)-(A) triblock copolymer consisting of polymer block (A) / polymer block (B) / polymer block (A) or a (B)-(A)-(B) triblock copolymer consisting of polymer block (B) / polymer block (A) / polymer block (B) can be obtained. In the above, using a block copolymer having two or more polymer blocks as polymer (a) allows for the production of even higher-order block copolymers.

[0059] In the solution polymerization method, the polymerization reaction is carried out using a known polymerization solvent. Various solvents can be used as the polymerization solvent, and examples thereof include saturated hydrocarbon compounds, aromatic compounds, ester compounds, ketone compounds, alcohol compounds, ether compounds, nitrile compounds, and water. As the polymerization solvent, it is preferable to use a solvent capable of dissolving the monomer, and it is more preferable to use an organic solvent capable of dissolving the monomer. Note that one type of polymerization solvent may be used alone, or two or more types may be used in combination.

[0060] Specific examples of polymerization solvents include saturated hydrocarbon compounds such as hexane, heptane, and cyclohexane; aromatic compounds such as benzene, toluene, xylene, and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl formate, and methyl propionate; ketone compounds such as acetone, methyl ethyl ketone, and cyclohexanone; alcohol compounds such as methanol, ethanol, and 2-propanol; ether compounds such as tetrahydrofuran; and nitrile compounds such as acetonitrile. Other polymerization solvents that may be used include dimethylformamide, dimethyl sulfoxide, and water. It is preferable to use a solvent capable of dissolving the monomer as the polymerization solvent. One polymerization solvent may be used alone, or two or more polymerization solvents may be used in combination.

[0061] From the viewpoint of improving purification efficiency, the boiling point of the polymerization solvent at atmospheric pressure is preferably 200° C. or lower, more preferably 150° C. or lower, and even more preferably 110° C. or lower. There are no particular restrictions on the lower limit of the boiling point of the polymerization solvent, but it is, for example, 50° C. or higher, preferably 55° C. or higher. When two or more polymerization solvents are used, it is preferable that the boiling points of the respective solvents be within the above range.

[0062] The amount of polymerization solvent used is preferably 5 to 200 parts by mass, more preferably 10 to 100 parts by mass, per 100 parts by mass of the total amount of monomers used in the polymerization reaction. Using 100 parts by mass or less of the polymerization solvent is preferred because a high polymerization rate can be achieved in a short time. Using 10 parts by mass or more of the polymerization solvent is also preferred because the heat of polymerization can be efficiently removed and an increase in the reaction temperature can be suppressed.

[0063] The reaction temperature and reaction time in the polymerization reaction can be appropriately set depending on the type of polymerization method used, the types of monomers and polymerization solvents used, etc. For example, in the case of the RAFT method, the reaction temperature is preferably 40°C or higher and 100°C or lower, more preferably 45°C or higher and 90°C or lower, and even more preferably 50°C or higher and 80°C or lower. A reaction temperature of 40°C or higher is preferred because it allows the polymerization reaction to proceed smoothly, while a reaction temperature of 100°C or lower is preferred because it can suppress side reactions and alleviates restrictions on the initiators and polymerization solvents that can be used. The reaction time is, for example, 1 hour or higher and 48 hours or lower, and preferably 2 hours or higher and 24 hours or lower.

[0064] The polymerization produces a polymer-containing solution containing a vinyl polymer and a polymerization solvent. In this production method, the polymer-containing solution obtained by polymerization may be used as is as a raw material mixture. Alternatively, the polymer-containing solution obtained by polymerization may be subjected to a known solvent removal treatment to isolate the polymer, and the isolated polymer may be dissolved in a solvent to prepare a polymer-containing solution. Furthermore, after carrying out the following reaction steps as necessary, the resulting polymer-containing solution may be used as is, or a solution obtained by isolating the polymer and dissolving it in a solvent may be used as a raw material mixture.

[0065] When the vinyl polymer obtained by the polymerization step has a thiocarbonylthio group derived from the RAFT agent, a step of reacting the vinyl polymer with a nucleophilic agent (hereinafter also referred to as the "reaction step") may be carried out to produce a polymer constituting the raw material mixture. According to this reaction step, a thiol group is generated from the thiocarbonylthio group possessed by the vinyl polymer, and the generated thiol group reacts with unreacted monomer remaining in the polymerization system to obtain a vinyl polymer from which the thiocarbonylthio group has been removed.

[0066] Examples of the nucleophilic agent include ammonia, primary and / or secondary amine compounds, alkali metal alkoxides, hydroxides, thiols, etc. Among these, from the viewpoint of reactivity, primary and / or secondary amine compounds are preferably used as the nucleophilic agent.

[0067] The number average molecular weight (Mn) of the polymer constituting the raw material mixture is, for example, in the range of 2,000 to 300,000. The Mn of the polymer is preferably 2,000 to 200,000, more preferably 2,500 to 150,000, and even more preferably 2,500 to 100,000. The molecular weight distribution (Mw / Mn), expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is, for example, 5.0 or less, preferably 4.0 or less, and more preferably 3.0 or less.

[0068] (Distillation system) In this production method, pre-purification is performed by thin-film distillation in the first step, followed by post-purification by thin-film distillation or flash distillation in the second step to recover the polymer, which is the target product of purification, from the raw material mixture. An example of the schematic configuration of a distillation system applicable to this production method is shown in Figures 1 and 2.

[0069] First, a distillation system 10 shown in Fig. 1 will be described. The distillation system 10 shown in Fig. 1 is applied when both pre-purification and post-purification are performed by thin-film distillation. As shown in Fig. 1, the distillation system 10 includes a raw material tank 11, a thin-film evaporator 12, a retentate receiver 13, a condenser 14, a distillate receiver 15, and a vacuum pump 26.

[0070] The raw material tank 11 is a container that contains the raw material mixture. A pipe 16 is connected to the raw material tank 11 to supply the raw material mixture to the thin film evaporator 12. The raw material mixture contained in the raw material tank 11 is supplied to the thin film evaporator 12 through the pipe 16 by driving a gear pump 17 provided in the pipe 16. A valve 18 that controls the flow and cut-off of the raw material mixture in the pipe 16 is provided upstream of the gear pump 17 in the pipe 16.

[0071] The thin-film evaporator 12 is an apparatus for performing thin-film distillation and includes a cylindrical or tubular main vessel 19, a heating surface 21 provided on the inner wall of the main vessel 19, and a wiper (stirring blade) 22 that rotates along the heating surface 21. The thin-film evaporator 12 shown in FIG. 1 is a vertical apparatus, and is arranged so that the axial direction of the main vessel 19 is the up-down direction (i.e., the direction in which the liquid flows downward). The heating surface 21 is heated by a heating means such as a circulating heat medium or a heater. Specific examples of the thin-film evaporator 12 include, but are not limited to, thin-film distillation apparatuses manufactured by Kobelco Eco-Solutions Co., Ltd. (product names: Exeba, Wiplen), thin-film evaporators manufactured by VTA, and short-stage evaporators.

[0072] The raw material mixture supplied to the thin film evaporator 12 is applied to the heating surface 21 by the rotation of the wiper 22, forming a liquid film on the heating surface 21. Furthermore, as the liquid film is heated on the heating surface 21, at least a portion of the volatile components contained in the liquid film evaporates and is discharged from the upper discharge port 23. On the other hand, the residual liquid that does not evaporate on the heating surface 21 and flows down from the heating surface 21 is discharged from the lower discharge port 24 and recovered in the residual liquid receiver 13 through the pipe 25. The recovered residual liquid contains the polymer contained in the raw material mixture in a state of increased purity (i.e., in a concentrated state). The rotation speed of the wiper 22 can be set appropriately depending on the viscosity of the raw material mixture, the supply speed, etc.

[0073] A condenser 14 is disposed downstream of the thin-film evaporator 12, and an upper outlet 23 is connected to the condenser 14 through a pipe. The volatile components discharged from the upper outlet 23 are condensed by the condenser 14 and recovered as a distillate in a distillate receiver 15. When a solution containing a polymer synthesized by solution polymerization and a polymerization solvent is used as the raw material mixture, the distillate recovered in the distillate receiver 15 by pre-purification can be reused as the polymerization solvent.

[0074] A cold trap 31 and a vacuum pump 26 are disposed downstream of the condenser 14. The internal pressures of the thin-film evaporator 12 (more specifically, the main vessel 19), the retentate receiver 13, and the distillate receiver 15 are reduced and controlled by a pressure control valve (not shown) under the operation of the vacuum pump 26.

[0075] Although FIG. 1 shows a vertical thin-film evaporator 12, it may also be configured to include a horizontal thin-film evaporator in which the axial direction of the main vessel 19 is horizontal. Furthermore, while FIG. 1 shows an external condenser type thin-film evaporator 12 in which the condenser 14 is provided outside the thin-film evaporator 12, it is also possible to use an internal condenser type thin-film evaporator in which the condenser 14 is provided inside the thin-film evaporator 12. The internal condenser type is preferable because it can quickly reduce the vapor partial pressure and increase the degree of saturation of the volatile component vapor. The raw material tank 11, retentate receiver 13, distillate receiver 15, and each pipe may be provided with a temperature-adjustable jacket around each component to heat, cool, or keep warm the liquid inside.

[0076] The retentate liquid receiver 13 is provided with a return pipe 27 that supplies the retentate liquid stored in the retentate liquid receiver 13 to the raw material tank 11. The return pipe 27 is provided with a gear pump 34 that supplies the retentate liquid in the retentate liquid receiver 13 to the raw material tank 11, and a return valve 28 that controls the flow and cut-off of the retentate liquid to the raw material tank 11. By operating the gear pump 34 with the valve 18 closed and the return valve 28 open, the retentate liquid in the retentate liquid receiver 13 is supplied to the raw material tank 11 through the return pipe 27. When returning the retentate liquid from the retentate liquid receiver 13 to the raw material tank 11, the pressure in the retentate liquid receiver 13 is temporarily returned to normal pressure. After the entire amount of the retentate liquid in the retentate liquid receiver 13 has been supplied to the raw material tank 11, the gear pump 34 is stopped, and with the return valve 28 closed, the retentate liquid is supplied from the raw material tank 11 to the thin-film evaporator 12 according to the same procedure as in pre-purification. As a result, pre-purification by the thin film evaporator 12 is followed by post-purification by the thin film evaporator 12, and a residual liquid with a further increased polymer purity is obtained.

[0077] Here, the residual liquid stored in the residual liquid receiver 13 from the thin film evaporator 12 by pre-purification corresponds to the first concentrated liquid, and the residual liquid stored in the residual liquid receiver 13 from the thin film evaporator 12 by post-purification corresponds to the second concentrated liquid. Hereinafter, the viscous liquid in which the polymer concentration has been increased by the distillation treatment will also be referred to as the "purified product," the first concentrated liquid as the "pre-purified product," and the second concentrated liquid as the "post-purified product."

[0078] The configuration of the distillation system when both pre-purification and post-purification are performed by thin-film distillation is not limited to that shown in Figure 1. For example, Figure 1 illustrates a configuration in which pre-purification and post-purification are performed using the same thin-film evaporator 12, but the distillation system 10 may be provided with multiple thin-film evaporators (a first thin-film evaporator and a second thin-film evaporator), with pre-purification performed using the first thin-film evaporator located upstream and post-purification performed using the second thin-film evaporator located downstream. Furthermore, Figure 1 illustrates a configuration in which a gear pump 34 is provided in the return pipe 27 and the residual liquid is returned to the raw material tank 11 by driving the gear pump 34. However, a tank for storing the residual liquid may be provided separately from the raw material tank 11, and post-purification may be performed by supplying the residual liquid from that tank to the thin-film evaporator 12.

[0079] Next, the distillation system 100 in Figure 2 will be described, focusing on the differences from Figure 1. The distillation system 100 in Figure 2 is applied when pre-purification is performed by thin film distillation and post-purification is performed by flash distillation.

[0080] 1, the distillation system 100 includes a raw material tank 11 and a thin-film evaporator 12 on the upstream side of the system. A first residual liquid receiver 13a is connected to a lower outlet 24 of the thin-film evaporator 12 through a pipe 25. The residual liquid that flows down from the heating surface 21 of the thin-film evaporator 12 is temporarily stored in the first residual liquid receiver 13a.

[0081] A flash tank 29 is connected downstream of the first retentate receiver 13a via piping 32. The flash tank 29 is a device that performs flash evaporation within a tank. The retentate stored in the first retentate receiver 13a is supplied to the flash tank 29 as the gear pump 33 is driven, and the supplied retentate is distilled in the flash tank 29. When the retentate is supplied from the first retentate receiver 13a to the flash tank 29, the pressure within the first retentate receiver 13a is temporarily returned to atmospheric pressure. The retentate after distillation in the flash tank 29 is recovered in the second retentate receiver 13b. This recovered retentate contains the polymer contained in the raw material mixture in a state of increased purity.

[0082] 1, the distillation system 100 is also provided with a condenser 14, a cold trap 31, and a vacuum pump 26. The internal pressures of the thin-film evaporator 12, the second retentate receiver 13b, and the distillate receiver 15 are reduced and controlled by a pressure control valve (not shown) under the operation of the vacuum pump 26.

[0083] In the distillation system 100, the raw material mixture contained in the raw material tank 11 is supplied to the thin film evaporator 12 by the gear pump 17, and pre-purification is carried out by the thin film evaporator 12, as in the distillation system 10. As a result, a retentate (corresponding to a first concentrated liquid) is obtained as a pre-purified product in the first retentate receiver 13a. The retentate recovered in the first retentate receiver 13a is then supplied to the flash tank 29 through the piping 32 by the gear pump 33. The flash tank 29 is controlled to a predetermined temperature and a predetermined pressure, and post-purification is carried out in the flash tank 29 whose temperature and pressure are controlled. The retentate (second concentrated liquid) recovered in the second retentate receiver 13b by post-purification contains a high concentration of the polymer that was contained in the raw material mixture.

[0084] (Purification conditions) In the pre-purification and post-purification of this production method, specific purification operations are performed under predetermined high-temperature and reduced-pressure conditions to reduce the amount of volatile components contained in the raw material mixture and obtain a viscous liquid (i.e., purified product) with an increased polymer concentration. In particular, in this production method, by setting specific temperature and pressure conditions in each of the pre-purification and post-purification operations, it is possible to obtain a polymer with high purity and sufficiently reduced odor while maintaining a high recovery rate of volatile components. The specific purification conditions for pre-purification and post-purification are as follows.

[0085] · First step (pre-purification) The supply rate of the raw material mixture when supplying the raw material mixture to the thin film evaporator 12 can be set appropriately depending on the viscosity of the raw material mixture and the scale of the thin film evaporator 12. For example, 2 In the case of a distillation system using a thin-film evaporator of about 1000 to 20000 g / h (hereinafter also referred to as "small-scale"), the feed rate of the raw material mixture is usually 500 to 30000 g / h, preferably 1000 to 20000 g / h, and more preferably 1000 to 15000 g / h.

[0086] Here, in the case of a distillation system using a full-scale thin-film evaporator (hereinafter also referred to as "large-scale"), the supply rate of the raw material mixture in the first step can be calculated using the following formula based on the heat transfer area of the thin-film evaporator. (Large-scale feed rate) = (Small-scale feed rate) × {(Large-scale heat transfer area) ÷ (Small-scale heat transfer area)} For example, the heat transfer area of a thin film evaporator is 0.11 m 2 The actual scale (heat transfer area: 2.5 m) was used to demonstrate the small-scale implementation with a raw material mixture feed rate of 10 kg / h. 2 When scaling up to 227 kg / h, the feed rate of the raw material mixture is calculated to be 227 kg / h.

[0087] The raw material mixture supplied to thin film evaporator 12 may be at room temperature, but is preferably preheated in order to reduce the viscosity of the raw material mixture and the load on gear pump 17. Specifically, the temperature of the raw material mixture supplied to thin film evaporator 12 (hereinafter also referred to as "raw material temperature") is, for example, 10 to 70°C, preferably 20 to 65°C, and more preferably 40 to 65°C.

[0088] In the purification operation (pre-purification) in the first step, the distillation temperature (more specifically, the internal temperature of the main vessel 19) is controlled within the range of 80 to 130°C. If the distillation temperature is below 80°C, the amount of volatile components in the raw material mixture may not be sufficiently reduced. For this reason, the distillation temperature during pre-purification is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher. On the other hand, if the distillation temperature is higher than 130°C, the polymer may deteriorate due to the thermal history applied to the polymer, and the odor may become stronger. From this perspective, the upper limit of the distillation temperature is preferably 125°C or lower, more preferably 120°C or lower.

[0089] The preferred range of the distillation temperature during pre-purification can be set by appropriately combining the above-mentioned upper and lower limits. The distillation temperature during pre-purification is preferably 90 to 130°C, more preferably 100 to 130°C, even more preferably 110 to 130°C, and still more preferably 110 to 120°C.

[0090] Furthermore, in the pre-purification, the pressure (more specifically, the internal pressure of the main vessel 19) is controlled within a range of 40 to 100 Torr. If the pressure is higher than 100 Torr, the amount of volatile components in the raw material mixture may not be sufficiently reduced. Furthermore, if an attempt is made to sufficiently reduce the amount of volatile components in the raw material mixture while setting the pressure high, it becomes necessary to set the evaporation temperature high, which raises concerns about increasing the thermal history of the polymer. From this perspective, the pressure during pre-purification is preferably 95 Torr or less, and more preferably 90 Torr or less. On the other hand, if the pressure is less than 40 Torr, it becomes necessary to lower the cooling water temperature of the condenser 14 to a lower temperature (for example, −5°C or less) in order to sufficiently recover the volatile components removed from the raw material mixture as a condensate, which results in an excessively high load on the refrigerator, and is therefore economically disadvantageous. From the viewpoint of increasing the recovery efficiency of volatile components (mainly solvents) and reducing the load on the refrigerator, the pressure during pre-purification is preferably 50 Torr or more, more preferably 60 Torr or more, even more preferably 65 Torr or more, and still more preferably 70 Torr or more.

[0091] The preferred pressure range during pre-purification can be set by appropriately combining the above-mentioned upper and lower limits. The pressure range during pre-purification is preferably 50 to 100 Torr, more preferably 60 to 100 Torr, even more preferably 65 to 100 Torr, still more preferably 70 to 100 Torr, even more preferably 70 to 95 Torr, and even more preferably 70 to 90 Torr.

[0092] The polymer content in the residual liquid (first concentrated liquid) obtained by pre-purification is preferably 97.0% by mass or more, more preferably 97.5% by mass or more, and even more preferably 98.0% by mass or more, based on the total amount of the first concentrated liquid. The polymer content in the first concentrated liquid is a value calculated using the above mathematical formula (1). Details of the calculation method follow the method described in the Examples below.

[0093] In the first concentrate, the content of volatile components calculated from the content of polymer converted to solid content (hereinafter also referred to as the "NV standard amount") is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and even more preferably 2.0% by mass or less, based on the total amount of the first concentrate. The lower limit of the NV standard amount in the first concentrate is not particularly limited, but is preferably 0.50% by mass or more, based on the total amount of the first concentrate. In the first step, by allowing some volatile components to remain in the first concentrate, pre-purification can be performed under relatively mild purification conditions that can minimize the thermal history of the polymer. The NV standard amount (mass%) is a value calculated by subtracting the content (mass%) of polymer contained in the first concentrate from the total amount (100% by mass) of the first concentrate. The content (mass%) of polymer contained in the first concentrate can be calculated using the above formula (1).

[0094] Furthermore, the content of volatile components in the first concentrate as measured by gas chromatography (GC) (hereinafter also referred to as "GC standard amount") is preferably 2.5 mass% or less, more preferably 2.0 mass% or less, and even more preferably 1.8 mass% or less, based on the total amount of the first concentrate. From the same viewpoint as the NV standard amount, the lower limit of the GC standard amount in the first concentrate is preferably 0.40 mass% or more based on the total amount of the first concentrate. Details of the method for measuring the GC standard amount follow the method described in the Examples below.

[0095] From the viewpoint of increasing purification efficiency, the polymer recovery rate by pre-purification is preferably 70% or more, more preferably 75% or more, and even more preferably 80% or more. In this specification, the polymer recovery rate is a value expressed as the ratio of the amount of recovered purified product to the total amount of the recovered purified product (hereinafter also referred to as "amount of recovered purified product") and the amount of condensed liquid of volatile components (hereinafter also referred to as "amount of volatile component condensed liquid"). The details of the calculation method follow the method described in the Examples below.

[0096] · Second process (post-purification) As in the first step, the supply rate of the raw material mixture in the second step can be set appropriately depending on the viscosity of the raw material mixture and the scale of the thin-film evaporator 12. In the case of a small-scale operation, the supply rate of the raw material mixture in the second step is usually 500 to 30,000 g / h, preferably 1,000 to 20,000 g / h, and more preferably 1,000 to 15,000 g / h. In the case of a large-scale operation, the supply rate of the raw material mixture in the second step can be calculated in the same manner as in the first step, based on the heat transfer area of the thin-film evaporator.

[0097] The raw material temperature in the second step is, for example, 10 to 70° C., and preferably 20 to 65° C. The raw material mixture supplied to the thin-film evaporator 12 is preferably preheated in the same manner as in the first step, from the viewpoint of lowering the viscosity of the raw material mixture and reducing the load on the pump, and is particularly preferably 40° C. or higher.

[0098] In the purification operation in the second step (post-purification), the distillation temperature is controlled within the range of 80 to 130°C, as in the purification operation in the first step (pre-purification). If the distillation temperature is lower than 80°C, the amount of volatile components in the first concentrated liquid tends to be insufficiently reduced. On the other hand, if the distillation temperature is higher than 130°C, the polymer tends to deteriorate due to the thermal history applied to the polymer, resulting in a stronger odor. Therefore, the distillation temperature in post-purification is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher. The upper limit of the distillation temperature is preferably 125°C or lower, more preferably 120°C or lower, from the viewpoint of suppressing deterioration of the polymer.

[0099] A preferred range of the distillation temperature during post-purification can be set by appropriately combining the above-mentioned upper and lower limits. The distillation temperature range during post-purification is preferably 90 to 130°C, more preferably 100 to 130°C, even more preferably 110 to 130°C, and still more preferably 110 to 120°C. In particular, from the viewpoint of simultaneously reducing the amount of volatile components in the purified product and reducing odor, it is preferred to set the distillation temperature during pre-purification and post-purification to preferably 90 to 130°C, more preferably 100 to 130°C, and even more preferably 110 to 130°C.

[0100] In addition, in post-purification, distillation is performed at a pressure lower than that in pre-purification. Here, in the pre-purification in the first step, thin-film distillation is performed at a moderately high vacuum level within a predetermined range (more specifically, 40 to 100 Torr), thereby suppressing thermal degradation of the polymer and improving the solvent recovery efficiency while reducing the load on the refrigerator. This first step allows the recovery of most of the volatile components contained in the raw material mixture before purification. However, it is difficult to completely remove the volatile components contained in the raw material mixture by pre-purification in the first step, and a small amount of these components will remain in the residual liquid (i.e., the first concentrated liquid).

[0101] Therefore, in the post-purification step in the second process, the distillation temperature is controlled within the same temperature range as in the pre-purification step to suppress thermal degradation of the polymer, and the pressure during distillation is set lower than in the pre-purification step to change the equilibrium state reached, thereby minimizing the amount of volatile components in the first concentrated liquid.

[0102] Specifically, the pressure during post-purification is preferably 30 Torr or less, more preferably 25 Torr or less, even more preferably 20 Torr or less, still more preferably 15 Torr or less, and even more preferably 10 Torr or less. There is no particular lower limit to the pressure during post-purification, but in order to suppress the power load on the capacitor 14, it is preferably 0.5 Torr or more, more preferably 1 Torr or more.

[0103] The preferred range of pressure during post-purification can be set by appropriately combining the above-mentioned upper and lower limits. The pressure range during post-purification is preferably 0.5 to 30 Torr, more preferably 0.5 to 25 Torr, even more preferably 1 to 20 Torr, and still more preferably 1 to 15 Torr.

[0104] In this production method, most of the volatile components contained in the raw material mixture before purification are recovered in the pre-purification process, so in the post-purification process, there is no need to consider the efficiency of recovering the volatile components in the raw material mixture as a condensate, and therefore there is no need to consider the load on the refrigerator. Therefore, in this production method, by setting the post-purification process under conditions of reduced pressure compared to the pre-purification process, in the post-purification process, priority is given to removing as many volatile components as possible from the first concentrated liquid rather than recovering them as a condensate. This allows for the production of a purified product with higher purity.

[0105] The residual liquid (second concentrate) obtained by post-purification preferably has a polymer content of 98.5% by mass or more, more preferably 98.8% by mass or more, and even more preferably 99.0% by mass or more, based on the total amount of the second concentrate. The polymer content in the second concentrate is a value calculated using the above mathematical formula (1), and details are given in accordance with the method described in the Examples below.

[0106] In the second concentrate, the content of volatile components (NV standard amount) calculated from the content of polymer converted to solid content is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.98% by mass or less, based on the total amount of the second concentrate. The NV standard amount (mass%) of the second concentrate is a value calculated by subtracting the content (mass%) of polymer contained in the second concentrate from the total amount (100% by mass) of the second concentrate. The content (mass%) of polymer contained in the second concentrate can be calculated using the above formula (1).

[0107] The content of volatile components in the second concentrate as measured by GC (GC standard amount) is preferably 1.2% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.90% by mass or less. The details of the method for measuring the GC standard amount follow the method described in the Examples below.

[0108] The purified product obtained by the purification operations of the first and second steps has a sufficiently reduced content of volatile impurities, and the purified polymer (hereinafter also referred to as "purified polymer") has a low odor. Therefore, the purified polymer obtained by this production method can be used in a wide range of applications. Specifically, it can be used in a variety of applications, such as sealants, adhesives, pressure-sensitive adhesives, paints, dispersants, industrial rubber, binders, coating agents, and surfactants. Other application fields include civil engineering and construction materials, packaging materials, automobile parts, home appliance and office equipment parts, medical equipment parts, electrical wires, and miscellaneous goods. [Example]

[0109] The present disclosure will be specifically described below based on examples, but the present disclosure is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Details of the analysis methods for the polymers obtained in the synthesis examples, production examples, examples, and comparative examples are as follows.

[0110] <Molecular weight measurement> The resulting polymer was subjected to gel permeation chromatography (GPC) under the conditions described below to obtain the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene. The molecular weight distribution (Mw / Mn) was calculated from the obtained values. GPC measurement conditions Column: Tosoh TSKgel SuperMultiporeHZ-M x 4 Solvent: tetrahydrofuran Temperature: 40℃ Detector: RI Flow rate: 600μL / min

[0111] <Measurement of polymer recovery rate and condensate recovery rate> The recovery rate (%) was calculated using the following formula: Polymer recovery rate = [Q1 ÷ (Q1 + Q2)] × 100 Condensate recovery rate = [Q2 ÷ (Q1 + Q2)] × 100 where Q1 represents the amount of purified product recovered, and Q2 represents the amount of condensed liquid of volatile components.

[0112] <Solid content (NV) measurement> 2 g of sample was placed in a pre-weighed aluminum cup, and after accurately weighing the aluminum cup, the sample was placed in a windless dryer and dried for 1 hour at 150° C. After drying, the weight of the aluminum cup was measured, and the NV (mass%) in the sample was calculated using the following formula: NV = [(W1-B) / (W0-B)] × 100 In the formula, B represents the weight (g) of the aluminum cup, W0 represents the total weight (g) of the sample and aluminum cup before drying in the airless dryer, and W1 represents the total weight (g) of the sample and aluminum cup after drying in the airless dryer.

[0113] <Measurement of residual monomer amount and residual solvent amount> The purified product thus obtained was subjected to gas chromatography (GC) measurement under the conditions described below, and the amounts of residual monomer and residual solvent were calculated. GC measurement conditions Equipment: GL Science GC-390B Column: CP-WAX 52CB (length 60 m x inner diameter 0.32 mm, film thickness 0.5 μm) DB-1 (length 30m x inner diameter 0.32mm, film thickness 1.0μm) Inlet temperature: 220℃ Detector temperature: 230℃ Column temperature: 40°C (5 min) → 7°C / min → 230°C (5 min) Detector: FID Preparation of measurement sample: 1.0 g of sample, tetrahydrofuran and acetone as dilution solvents, 0.02g of isobutyl acrylate as a standard substance

[0114] <Odor intensity> The odor intensity of the polymer was measured by the following method. 1 g of the purified product was placed in a test tube, and a scent bag (manufactured by AS ONE Corporation) was attached to the test tube. After heating at 60°C for 30 minutes, the scent intensity in the scent bag was evaluated by sensory evaluation. The sensory evaluation panel consisted of five members, each of whom prepared a separate odorless bag and compared it with the sample (smell bag) to evaluate it. The evaluation was based on the following criteria, with a score of 6 points between 0 and 5, and the average score was used to determine the odor intensity of the sample. A break of at least 3 minutes was taken between evaluations of each sample. 0 points: Odorless 1 point: barely detectable odor 2 points: A weak odor that is easy to identify 3 points: Easily detectable odor 4 points: Strong odor 5 points: Strong odor

[0115] 1. Synthesis example (Synthesis Example 1: Production of Polymer a) A 100 L reactor equipped with a stirring blade, thermometer, and condenser was charged with 2.0 kg of S,S-dibenzyltrithiocarbonate (DBTTC) as a RAFT agent, 85 g of 2,2'-azobis(2,4-dimethylvaleronitrile) as a polymerization initiator, 17 kg of n-butyl acrylate (nBA), 1.2 kg of ethyl acrylate (EA), 4.7 kg of tetradecyl acrylate (TDA), and 4.7 kg of methyldimethoxysilylpropyl methacrylate as monomers, 24 kg of ethyl acetate as a polymerization solvent, and 6.0 kg of trimethyl orthoacetate (MOA). The mixture was thoroughly degassed with nitrogen bubbling and heated to 58 °C to initiate polymerization. After 2 hours, the mixture was heated to 70 °C over 1 hour and then continued at 70 °C for an additional 4 hours. Thereafter, the mixture was cooled to room temperature to stop the reaction, thereby obtaining polymer a. The molecular weight of polymer a was Mn 4,300, Mw 6,000, and Mw / Mn 1.40 as measured by GPC (gel permeation chromatography) (in terms of polystyrene).

[0116] (Synthesis Example 2: Production of Triblock Copolymer b) A 400 L reactor equipped with a stirrer, thermometer, condenser, and monomer mixing vessel and capable of reducing the pressure inside the vessel was charged with Polymer a (26 kg) obtained in Synthesis Example 1, nBA (57 kg), EA (3.8 kg), TDA (15 kg), 2,2'-azobis(2-methylbutyronitrile) (hereinafter also referred to as "ABN-E") (97 g), ethyl acetate (136 kg), and MOA (9.4 kg). The reactor was thoroughly degassed by nitrogen bubbling, and the temperature was raised to 70°C. When the internal temperature reached approximately 60°C, the pressure inside the reactor was reduced to 43 kPa. When the internal temperature reached approximately 70°C, it was confirmed that reflux became intense. The polymerization was initiated when the internal temperature reached 70°C, and the external temperature was kept constant at 40°C. The degree of vacuum was adjusted, and the internal temperature was kept constant at 70°C by refluxing. Separately, a monomer mixture solution was prepared by stirring and mixing nBA (113 kg), EA (7.6 kg), and TDA (30 kg) in a monomer mixing tank equipped with the reactor. Thirty minutes after the start of polymerization, this prepared monomer mixture solution was continuously fed into the reactor over 4 hours. Three hours after the start of polymerization, the reduced pressure was released and the reactor was returned to atmospheric pressure. After the continuous feed of the monomer mixture solution was completed, a mixed solution of ABN-E (57 g) and ethyl acetate (1.0 kg) was fed into the reactor, and the internal temperature was raised to 60°C over 30 minutes. Eight hours after the start of polymerization, the polymer solution containing triblock copolymer b in the reactor was cooled to room temperature to terminate the reaction. The molecular weight of triblock copolymer b was determined by GPC measurement (polystyrene equivalent) to be Mn 70,200, Mw 84,900, and Mw / Mn 1.21.

[0117] (Synthesis Example 3: Production of Pentablock Polymer c) Methyldimethoxysilylpropyl methacrylate (2.1 kg), ABN-E (199 g), and MOA (316 g) were added to the solution containing triblock copolymer b obtained by polymerization in Synthesis Example 2, and the mixture was thoroughly degassed by bubbling nitrogen. The temperature was raised to 60°C to initiate polymerization. After 7 hours, the mixture was cooled to room temperature to terminate the reaction, yielding a solution containing pentablock copolymer c (hereinafter also referred to as "solution e"). The molecular weight of the resulting pentablock copolymer c was Mn 76,500, Mw 98,100, and Mw / Mn 1.28, as determined by GPC measurement (polystyrene equivalent). Pentablock copolymer c has a polymer block (A) consisting of nBA, EA, TDA, and methyldimethoxysilylpropyl methacrylate, and a polymer block (B) consisting of nBA, EA, and TDA, and is a pentablock copolymer with a block structure of (A)-(B)-(A)-(B)-(A). Based on the polymerization rate, the composition ratio of polymer block (A) to polymer block (B) was (A) / (B) / (A) / (B) / (A) = 2.4 / 43.7 / 7.8 / 43.7 / 2.4 (wt%), which means that (A) / (B) is approximately 13 / 87 (wt%).

[0118] 2. Manufacturing example (Production Example 1: Production of polymer-containing solution A) Solution e obtained in Synthesis Example 3 was bubbled with nitrogen and thoroughly degassed, after which n-propylamine (880 g, 5 molar equivalents relative to the thiocarbonylthio groups of pentablock copolymer c) was added and heated to 40°C to initiate the decomposition reaction of the thiocarbonylthio groups. After 5 hours, the reaction was stopped by cooling to room temperature, and a solution containing triblock copolymer d (hereinafter also referred to as "polymer-containing solution A") was obtained. The obtained triblock copolymer d is a triblock copolymer having a polymer block (A) consisting of nBA, EA, TDA, and methyldimethoxysilylpropyl methacrylate, and a polymer block (B) consisting of nBA, EA, and TDA, and has an (A)-(B)-(A) block structure. 1 H-NMR measurements confirmed that the peak (4.8 ppm) of hydrogen bonded to the carbon adjacent to the thiocarbonylthio group observed in pentablock copolymer c disappeared in triblock copolymer d, and peaks (3.3 ppm, 2.9 ppm) derived from the molecular structure resulting from the Michael addition with the residual acrylate compound (terminal molecular structure represented by the following formula (3)) appeared. From these results, it can be said that triblock copolymer d is a Michael adduct of the thiol formed by decomposition of the trithiocarbonate group of pentablock copolymer c with n-propylamine and the residual acrylate compound contained in solution e. The molecular weights of triblock copolymer d were Mn 44,600, Mw 59,500, and Mw / Mn 1.33 as determined by GPC (polystyrene equivalent). The average number of crosslinkable functional groups per molecule of polymer block (A) was calculated from the amount of methyldimethoxysilylpropyl methacrylate introduced per RAFT agent, and was found to be 3.0. The viscosity of polymer-containing solution A was 5,200 mPa s, the NV was 79.6 mass%, the amount of residual monomer was 1.4 mass% (breakdown: BA: 1.1 mass%, EA: less than 0.1 mass%, TDA: 0.3 mass%), and the amount of residual solvent (total amount of polymerization solvent and dehydrating agent; the same applies hereinafter) was 19.0 mass% (breakdown: ethyl acetate: 14.1 mass%, MOA: 4.9 mass%). [ka] (In formula (3), R represents a residue obtained by removing an acryloyloxy group from an acrylic ester compound contained in a monomer that constitutes the molecular chain of the polymer.)

[0119] (Production Example 2: Production of polymer-containing solution B) The temperature of a 1,000 mL oil-jacketed pressurized stirred tank reactor was maintained at 200°C. Next, while maintaining the pressure in the reactor constant, an operation was started to continuously supply a mixture consisting of nBA (85 parts by mass), TDA (10 parts by mass), and trimethoxysilylpropyl methacrylate (hereinafter also referred to as "TMS") (5 parts by mass) as monomers, 2-propanol (hereinafter also referred to as "IPA") (5 parts by mass) and methyl ethyl ketone (hereinafter also referred to as "MEK") (5 parts by mass) as polymerization solvents, MOA (3 parts by mass) as a dehydrating agent, and di-t-hexyl peroxide (NOF Corporation, trade name "Perhexyl D") (0.1 part by mass) as a polymerization initiator (i.e., a mixture of monomers, polymerization solvent, dehydrating agent, and polymerization initiator; hereinafter also referred to as "monomer mixture") from a raw material tank to the reactor at a constant supply rate (48 g / min, residence time: 12 minutes), and a reaction liquid equivalent to the amount of the monomer mixture supplied was continuously withdrawn from the outlet. Immediately after the start of the reaction, the reaction temperature dropped once, and then a temperature rise due to the heat of polymerization was observed, but the reaction temperature was maintained at 199 to 201°C by controlling the temperature of the oil jacket. The point at which the temperature stabilized after the start of the monomer mixture supply was designated as the start point for collecting the reaction solution, and the reaction was continued for 2 hours from the start point. As a result, 5.76 kg of the monomer mixture was supplied and 5.76 kg of the reaction solution was collected, yielding a solution containing polymer e (hereinafter also referred to as "polymer-containing solution B"). The obtained polymer e had Mn of 3,400, Mw of 7,600, and Mw / Mn of 2.24 as determined by GPC (polystyrene equivalent). The viscosity of polymer-containing solution B was 3,700 mPa s, the NV was 78.8 mass%, the amount of residual monomer was 9.7 mass% (breakdown: BA: 8.2 mass%, TDA: 1.0 mass%, TMS: 0.5 mass%), and the amount of residual solvent was 11.5 mass% (breakdown: IPA: 4.4 mass%, MEK: 4.4 mass%, MOA: 2.7 mass%). Furthermore, the number of crosslinkable functional groups per molecule contained in polymer e was calculated from the amount of residual TMS monomer and Mn of polymer e, and was found to be 0.69 on average.

[0120] 3. Examples and Comparative Examples Example 1 External condenser type horizontal thin film evaporator (VTA VDL-70-4, heat transfer area 0.04 m) 2 Using a stirring blade (RSS type), the polymer-containing solution A obtained in Production Example 1 was purified by the following pre-purification and post-purification. First, polymer-containing solution A was heated to 60°C in a jacketed tank. The heated polymer-containing solution A was then fed from the jacketed tank (raw material tank) to a thin-film evaporator using a gear pump at a feed rate of 1,330 g / hr, and pre-purification was performed. The pre-purification conditions were an evaporator temperature (distillation temperature) of 120°C, a vacuum of 75 Torr, a blade rotation speed of 1,000 rpm, and a condenser cooling temperature of 0°C. The pre-purified product and volatile component condensate were continuously discharged from the apparatus and collected in tanks (residue liquid receiver and distillate receiver), respectively. The polymer recovery rate from pre-purification was 83.2%, and the volatile component condensate recovery rate was 16.8%. GC analysis confirmed that the pre-purified product contained nonvolatile components (solvents) such as ethyl acetate and MOA, and that no decomposition of the solvent had occurred. The content of volatile components remaining in the pre-purified product based on NV was 1.93% by mass (NV: 98.07% by mass), the content of volatile components based on GC was 1.16% by mass (residual monomer amount: 0.70% by mass, residual solvent amount: 0.46% by mass), and the odor intensity was 2.2 (see Table 1). Next, the pre-purified product was heated to 60°C, and post-purification was carried out using a thin-film evaporator under the same conditions as for pre-purification, except that the degree of vacuum was changed to 15 Torr and the feed rate was changed to 1180 g / hr, to obtain a viscous liquid (post-purified product) containing a purified polymer. No volatile component condensate was recovered in the post-purification, and the recovery rate of the volatile component condensate was 0.0%. The content of volatile components remaining in the post-purification product based on NV was 0.94% by mass (NV: 99.06% by mass), the content of volatile components based on GC was 0.54% by mass (residual monomer: 0.42% by mass, residual solvent: 0.12% by mass), and the odor intensity was 2.2 (see Table 1).

[0121] <Examples 2 and 3> Pre-purification was carried out in the same manner as in Example 1 to obtain a pre-purified product, and post-purification was carried out in the same manner as in Example 1 to obtain a viscous liquid (post-purified product), except that the pre-purified product was heated to 60°C and then the degree of vacuum was set to the value shown in Table 1. Table 1 shows the NV, GC analysis results (amount of residual monomer, amount of residual solvent), content of residual volatile components based on NV, content of residual volatile components based on GC, and odor intensity for the purified products of each Example.

[0122] Example 4 Internal condenser type vertical thin film evaporator (VTA VKL70-4, heat transfer area 0.04 m) 2 Using a stirring blade: SKR type block wiper) and a flash tank (flash evaporator), the polymer-containing solution A obtained in Production Example 1 was purified by the following pre-purification and post-purification. First, polymer-containing solution A was heated to 60°C in a jacketed tank. The heated polymer-containing solution A was then fed from the jacketed tank to a thin-film evaporator using a gear pump at a feed rate of 1,050 g / hr, and pre-purification was performed. The pre-purification conditions were an evaporator temperature (distillation temperature) of 120°C, a vacuum of 75 Torr, a blade rotation speed of 400 rpm, and a condenser cooling temperature of 0°C. The pre-purified product and volatile component condensate were continuously discharged from the apparatus and collected in tanks (residue liquid receiver and distillate receiver), respectively. The polymer recovery rate from pre-purification was 82.3%, and the volatile component condensate recovery rate was 17.7%. GC analysis confirmed that the pre-purified product contained nonvolatile components (solvents) such as ethyl acetate and MOA, and that no decomposition of the solvent had occurred. The content of volatile components remaining in the pre-purified product based on NV was 1.05% by mass (NV: 98.95% by mass), the content of volatile components based on GC was 0.56% by mass (residual monomer amount: 0.46% by mass, residual solvent amount: 0.10% by mass), and the odor intensity was 2.0 (see Table 1). The pre-purified product was then heated to 60°C and fed to a flash tank at a feed rate of 1,030 g / hr, where it was flash evaporated to give a viscous liquid (post-purified product). The post-purification conditions were a jacket temperature (distillation temperature) of 120°C and a vacuum of 1 Torr. No volatile component condensate was recovered in the post-purification, and the recovery rate of the volatile component condensate was 0.0%. In the post-purification product, the content of residual volatile components based on NV was 0.90% by mass (NV: 99.10% by mass), the content of residual volatile components based on GC was 0.47% by mass (residual monomer amount: 0.41% by mass, residual solvent amount: 0.06% by mass), and the odor intensity was 2.0 (see Table 1).

[0123] <Example 5> External condenser type vertical thin film evaporator (Kobe Eco-Solutions Co., Ltd., Exeba EX-02 type, heat transfer area 0.2 m) 2 ) was used to purify the polymer-containing solution A obtained in Production Example 1 by the following pre-purification and post-purification. First, polymer-containing solution A was charged into a jacketed tank. While maintaining the temperature at room temperature (25°C), polymer-containing solution A was fed from the jacketed tank to a thin-film evaporator using a gear pump at a feed rate of 10,000 g / hr, and pre-purification was performed. The pre-purification conditions were an evaporator temperature (distillation temperature) of 120°C, a vacuum of 70 Torr, a blade rotation speed of 800 rpm, and a condenser cooling temperature of 5°C. The pre-purified product and volatile component condensate were continuously discharged from the apparatus (more specifically, the lower screw section rotating at 100 rpm for the pre-purified product) and collected in tanks (residue receiver and distillate receiver), respectively. The polymer recovery rate from pre-purification was 85.3%, and the volatile component condensate recovery rate was 14.7%. GC analysis confirmed that the pre-purified product contained nonvolatile components (solvents) such as ethyl acetate and MOA, and that no decomposition of the solvent had occurred. The content of volatile components remaining in the pre-purified product based on NV was 1.80% by mass (NV: 98.20% by mass), the content of volatile components based on GC was 1.00% by mass (residual monomer amount: 0.36% by mass, residual solvent amount: 0.64% by mass), and the odor intensity was 2.2 (see Table 1). Next, the pre-purified product was heated to 50°C, and post-purification was carried out under the same conditions as pre-purification, except that the vacuum level was changed to 10 Torr and the feed rate was changed to 8000 g / hr, to obtain a viscous liquid (post-purified product). No volatile component condensate was recovered in the post-purification, and the recovery rate of the volatile component condensate was 0.0%. In the post-purification product, the content of residual volatile components based on NV was 0.82% by mass (NV: 99.18% by mass), the content of residual volatile components based on GC was 0.31% by mass (residual monomer amount: 0.23% by mass, residual solvent amount: 0.08% by mass), and the odor intensity was 2.0 (see Table 1).

[0124] Example 6 External condenser type vertical thin film evaporator (Kobe Eco Solutions Co., Ltd., Wiplen 6-1 type, heat transfer area 0.11 m) 2 ) was used to purify the polymer-containing solution A obtained in Production Example 1 by the following pre-purification and post-purification. First, polymer-containing solution A was placed in a jacketed tank. While maintaining the temperature at room temperature (25°C), polymer-containing solution A was fed from the jacketed tank to a thin-film evaporator using a gear pump at a feed rate of 10,000 g / hr, and pre-purification was performed. The pre-purification conditions were an evaporator temperature (distillation temperature) of 120°C, a vacuum of 70 Torr, a blade rotation speed of 450 rpm, and a condenser cooling temperature of 5°C. The pre-purified product and condensed volatile components were continuously discharged from the apparatus and collected in tanks (residue liquid receiver and distillate receiver), respectively. The polymer recovery rate from pre-purification was 85.2%, and the volatile component condensed liquid recovery rate was 14.8%. GC analysis confirmed that the pre-purified product contained non-volatile components (solvents) such as ethyl acetate and MOA, and that no decomposition of the solvent had occurred. The content of volatile components remaining in the pre-purified product based on NV was 1.90% by mass (NV: 98.10% by mass), the content of volatile components based on GC was 0.97% by mass (residual monomer amount: 0.36% by mass, residual solvent amount: 0.61% by mass), and the odor intensity was 2.0 (see Table 1). Next, the pre-purified product was heated to 80°C, and post-purification was carried out under the same conditions as pre-purification, except that the vacuum level was changed to 10 Torr and the feed rate to 20,000 g / hr, to obtain a viscous liquid (post-purified product). No volatile component condensate was recovered in the post-purification, and the recovery rate of the volatile component condensate was 0.0%. In the post-purification product, the content of residual volatile components based on NV was 0.87% by mass (NV: 99.13% by mass), the content of residual volatile components based on GC was 0.58% by mass (residual monomer amount: 0.19% by mass, residual solvent amount: 0.39% by mass), and the odor intensity was 2.0 (see Table 1).

[0125] Example 7 Internal condenser type vertical thin film evaporator (VTA VKL70-4, heat transfer area 0.04 m) 2 Using a stirring blade: SKR type block wiper) and a flash tank, the polymer-containing solution B obtained in Production Example 2 was purified by the following pre-purification and post-purification. First, polymer-containing solution B was heated to 60°C in a jacketed tank and then fed from the jacketed tank to a thin-film evaporator using a gear pump at a feed rate of 1,050 g / hr for pre-purification. The pre-purification conditions were an evaporator temperature (distillation temperature) of 120°C, a vacuum of 75 Torr, an impeller rotation speed of 400 rpm, and a condenser cooling temperature of 0°C. The pre-purified product and condensed volatile components were continuously discharged from the apparatus and collected in tanks (residue liquid receiver and distillate receiver), respectively. The polymer recovery rate from pre-purification was 79.9%, and the volatile component condensed liquid recovery rate was 20.1%. GC analysis confirmed that the pre-purified product contained nonvolatile components (solvents) such as IPA, MOA, and MEK, and that no decomposition of the solvent had occurred. The content of volatile components remaining in the pre-purified product based on NV was 1.38% by mass (NV: 98.62% by mass), the content of volatile components based on GC was 0.68% by mass (residual monomer amount: 0.61% by mass, residual solvent amount: 0.07% by mass), and the odor intensity was 1.6 (see Table 1). The pre-purified product was then heated to 60°C and fed to a flash tank at a feed rate of 1050 g / hr, where it was flash evaporated to give a viscous liquid (post-purified product). The post-purification conditions were a jacket temperature (distillation temperature) of 120°C and a vacuum of 1 Torr. No volatile component condensate was recovered in the post-purification, and the recovery rate of the volatile component condensate was 0.0%. In the post-purification product, the content of residual volatile components based on NV was 0.84% by mass (NV: 99.16% by mass), the content of residual volatile components based on GC was 0.45% by mass (residual monomer amount: 0.45% by mass, residual solvent amount: less than the detection limit (0.01% by mass)), and the odor intensity was 1.4 (see Table 1).

[0126] <Comparative Example 1> External condenser type horizontal thin film evaporator (VTA VDL-70-4, heat transfer area 0.04 m) 2 Using a stirring blade (RSS type), the polymer-containing solution A obtained in Production Example 1 was purified by the following procedure. First, polymer-containing solution A was heated to 60°C in a jacketed tank. The heated polymer-containing solution A was then fed from the jacketed tank to a thin-film evaporator using a gear pump at a feed rate of 1,330 g / hr for purification (single purification). The purification conditions were evaporator temperature (distillation temperature) 120°C, vacuum 75 Torr, impeller rotation speed 1,000 rpm, and condenser cooling temperature 0°C. The viscous liquid purified product and volatile component condensate were continuously discharged from the apparatus and collected in tanks (residue liquid receiver and distillate receiver), respectively. The polymer recovery rate from purification was 82.9%, and the volatile component condensate recovery rate was 16.7%. GC analysis confirmed that the purified product contained nonvolatile components (solvents) such as ethyl acetate and MOA, and that no decomposition of the solvent had occurred. In the purified product, the content of residual volatile components based on NV was 1.93% by mass (NV: 98.07% by mass), the content of residual volatile components based on GC was 1.16% by mass (residual monomer amount: 0.70% by mass, residual solvent amount: 0.46% by mass), and the odor intensity was 2.2 (see Table 2).

[0127] <Comparative Examples 2 to 8> Polymer-containing solution A was heated to 60°C in a jacketed tank, and then purification (single purification) was carried out in the same manner as in Comparative Example 1, except that the feed rate, evaporator temperature (distillation temperature), degree of vacuum, and impeller rotation speed were set to the values shown in Table 2, to obtain a viscous liquid purified product. The NV, GC analysis results (amount of residual monomer, amount of residual solvent), content of residual volatile components based on NV, content of residual volatile components based on GC, and odor intensity of the purified product of each Comparative Example are shown in Table 2. Note that for Comparative Examples 2 and 3, GC analysis and odor intensity measurement were not carried out because the NV was low and devolatilization was insufficient.

[0128] <Comparative Example 9> Internal condenser type vertical thin film evaporator (VTA VKL70-4, heat transfer area 0.04 m) 2 Using a stirring blade: SKR type block wiper, the polymer-containing solution A obtained in Production Example 1 was purified (single purification) by the following procedure. First, polymer-containing solution A was heated to 60°C in a jacketed tank. The heated polymer-containing solution A was then purified by feeding it from the jacketed tank to a thin-film evaporator using a gear pump at a feed rate of 1050 g / hr. The purification conditions were evaporator temperature (distillation temperature) 120°C, vacuum level 75 Torr, impeller rotation speed 400 rpm, and condenser cooling temperature 0°C. The viscous liquid purified product and volatile component condensate were continuously discharged from the apparatus and collected in tanks (residue liquid receiver and distillate receiver), respectively. The polymer recovery rate after purification was 82.3%, and the volatile component condensate recovery rate was 17.7%. GC analysis confirmed that the purified product contained nonvolatile components (solvents) such as ethyl acetate and MOA, and that no decomposition of the solvent had occurred. In the purified product, the content of residual volatile components based on NV was 1.05% by mass (NV: 98.95% by mass), the content of residual volatile components based on GC was 0.56% by mass (residual monomer amount: 0.46% by mass, residual solvent amount: 0.10% by mass), and the odor intensity was 1.8 (see Table 2).

[0129] <Comparative Example 10> External condenser type vertical thin film evaporator (Kobe Eco-Solutions Exeba EX-02 type, heat transfer area 0.2 m) 2 ) was used to purify the polymer-containing solution A obtained in Production Example 1 (purification twice) by the following procedure. First, polymer-containing solution A was placed in a jacketed tank. While maintaining room temperature (25°C), polymer-containing solution A was fed from the jacketed tank to a thin-film evaporator using a gear pump at a feed rate of 10,000 g / hr for pre-purification. The pre-purification conditions were an evaporator temperature (distillation temperature) of 120°C, a vacuum of 70 Torr, a blade rotation speed of 800 rpm, and a condenser cooling temperature of 5°C. The pre-purified product and volatile component condensate were continuously discharged from the apparatus (the pre-purified product was, more specifically, the lower screw section rotating at 100 rpm) and collected in tanks (a retentate receiver and a distillate receiver), respectively. The polymer recovery rate from pre-purification was 85.3%, and the volatile component condensate recovery rate was 14.7%. GC analysis confirmed that the pre-purified product contained nonvolatile components (solvents) such as ethyl acetate and MOA, and that no decomposition of the solvent had occurred. In the pre-purified product, the amount of residual monomer was 0.36% by mass, the amount of residual solvent was 0.64% by mass, the NV was 98.20% by mass, and the odor intensity was 2.2. Next, the pre-purified product was heated to 50°C, and post-purification was carried out under the same conditions as pre-purification, except that the feed rate was changed to 8000 g / hr, to obtain a viscous liquid post-purified product. The recovery rate of the volatile component condensate after post-purification was 0.0%. In the post-purification product, the content of residual volatile components based on NV was 1.27% by mass (NV: 98.73% by mass), the content of residual volatile components based on GC was 0.63% by mass (residual monomer amount: 0.28% by mass, residual solvent amount: 0.35% by mass), and the odor intensity was 2.2 (see Table 2).

[0130] <Comparative Example 11> External condenser type vertical thin film evaporator (Kobe Eco-Solutions Wiplen 6-1 type, heat transfer area 0.11 m) 2 ) was used to purify the polymer-containing solution A obtained in Production Example 1 (single purification) by the following procedure. First, polymer-containing solution A was charged into a jacketed tank. While maintaining the temperature at room temperature (25°C), polymer-containing solution A was fed from the jacketed tank to an evaporator using a gear pump at a feed rate of 10,000 g / hr, and purified. The purification conditions were evaporator temperature (distillation temperature) of 120°C, vacuum of 70 Torr, impeller rotation speed of 450 rpm, and condenser cooling temperature of 5°C. The viscous liquid purified product and volatile component condensate were continuously discharged from the apparatus and collected in tanks (residue liquid receiver and distillate receiver), respectively. The polymer recovery rate after purification was 85.2%, and the volatile component condensate recovery rate was 14.8%. GC analysis confirmed that the purified product contained nonvolatile components (solvents) such as ethyl acetate and MOA, and that no decomposition of the solvent had occurred. In the purified product, the content of residual volatile components based on NV was 1.90% by mass (NV: 98.10% by mass), the content of residual volatile components based on GC was 0.97% by mass (residual monomer amount: 0.36% by mass, residual solvent amount: 0.61% by mass), and the odor intensity was 2.0 (see Table 2).

[0131] [Table 1]

[0132] [Table 2]

[0133] <Manufacturing results> As is clear from the results of Examples 1 to 7, this production method enabled the content of volatile components remaining in the post-purification product, the final target, to be 1.0 mass% or less, based on both the NV standard and GC standard of the polymer. Furthermore, this production method enabled the production of a polymer with little odor. Furthermore, the polymer, the target of purification, could be recovered while suppressing decomposition of volatile components during the purification process.

[0134] On the other hand, when the polymer-containing solutions A and B were purified only in the manner equivalent to the first step of this production method, the content of residual volatile components determined based on the NV standard of the polymer exceeded 1.0% by mass in Comparative Examples 1 to 5, 9, and 11, and the amount of volatile components remaining in the final target product was not sufficiently reduced. Furthermore, in Comparative Examples 6 to 8, the odor intensity was 3 or higher, and the odor could not be sufficiently reduced. Even when purification was performed twice, in Comparative Example 10, where the degree of vacuum in the second step of this production method was the same as that in the first step, the content of residual volatile components based on the NV standard in the obtained purified product exceeded 1.0% by mass, and the content of volatile components could not be sufficiently reduced. [Explanation of symbols]

[0135] 10,100...Distillation system, 11...raw material tank, 12...thin film evaporator, 13...residue receiver, 13a...first residue receiver, 13b...second residue receiver, 14...condenser, 15...distillate receiver, 17,33,34...gear pump, 21...heating surface, 22...wiper, 29...flash tank, 31...cold trap

Claims

1. a first step of treating a mixed liquid containing a polymer and a solvent using a thin-film evaporator at a temperature of 80 to 130°C and a pressure of 60 to 100 Torr to reduce the amount of volatile components in the mixed liquid, thereby obtaining a first concentrated liquid containing the polymer; a second step of treating the first concentrated liquid using a thin film evaporator or a flash evaporator at a temperature of 80 to 130°C and at a pressure lower than the pressure during distillation in the first step to reduce the amount of volatile components in the first concentrated liquid, thereby obtaining a second concentrated liquid containing the polymer; Including, the polymer is a (meth)acrylic polymer obtained by a RAFT method, In the second step, the first concentrated liquid is treated at a pressure of 15 Torr or less.

2. 2. The method for producing a polymer according to claim 1, wherein in the second step, the first concentrated liquid is treated at a pressure of 10 Torr or less.

3. The method for producing a polymer according to claim 1 or 2, wherein the (meth)acrylic polymer is a block copolymer having two or more polymer blocks.

4. The method for producing a polymer according to any one of claims 1 to 3, wherein the mixture has a viscosity of 500 to 100,000 mP·s at 25°C.

5. The method for producing a polymer according to any one of claims 1 to 4, wherein the treatment temperature in the first step and the treatment temperature in the second step are 100 to 130°C.

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