Method for producing copolymers

Abstract

To provide a copolymer that allows adequate control of its molecular weight and molecular weight distribution, with the molecular weight being sufficiently large and the molecular weight distribution being small, and a method for producing the same.SOLUTION: A method for producing a copolymer includes a step for polymerizing a polymerizable composition containing a vinyl polymer (A), a vinyl monomer (B) and a polymerization catalyst (C). The vinyl polymer (A) has in each molecule 0.8-2.9 iodine atoms and the number average molecular weight, Mn(A), is 3,000-100,000. The vinyl monomer (B) comprises a monomer having two or more vinyl groups in each molecule, of 30 mol% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing copolymers and copolymers. [Background technology]

[0002] Vinyl polymers obtained by polymerizing vinyl monomers are used in a variety of applications, and in particular, there is a demand for vinyl polymers with high molecular weight and controlled molecular weight distribution to meet mechanical property requirements. Methods for simultaneously controlling the molecular weight and molecular weight distribution of polymers include living anionic polymerization and living radical polymerization. While these polymerization methods can produce polymers with high molecular weight and narrow molecular weight distribution, they require the use of special compounds or metal catalysts. Therefore, a process to remove these compounds or catalysts is necessary, which poses a challenge in terms of industrial complexity.

[0003] Therefore, in recent years, reversible transfer catalytic polymerization (RTCP) (Patent Document 1) and reversible complex formation-mediated polymerization (RCMP) (Patent Documents 2 and 3) have been developed as living radical polymerization methods that do not use special compounds or metal catalysts. These polymerization methods are known to have a low burden on the removal process and to provide excellent polymerization control because they use organic iodine compounds or iodide salts with low toxicity as catalysts. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2008 / 139980 [Patent Document 2] International Publication No. 2011 / 016166 [Patent Document 3] International Publication No. 2013 / 027419 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in the methods described in Patent Documents 1 to 3, it was difficult to synthesize polymers having a high molecular weight with a number average molecular weight of 100,000 or more. In particular, the synthesis of polymers having a high molecular weight and a small molecular weight distribution, which are necessary to meet the mechanical property requirements, has not been reported so far.

[0006] An object of the present invention is to provide a copolymer in which the molecular weight and the molecular weight distribution can be sufficiently controlled, the molecular weight is sufficiently large, and the molecular weight distribution is small, and a method for producing the same.

Means for Solving the Problems

[0007] The present invention has the following constitution. [1] A method for producing a copolymer, comprising a step of polymerizing a polymerizable composition containing a vinyl polymer (A), a vinyl monomer (B) and a polymerization catalyst (C), wherein the vinyl polymer (A) has 0.8 to 2.9 iodine atoms in the molecule, and when the number average molecular weight of the vinyl polymer (A) is Mn(A), Mn(A) is 3,000 to 100,000, and the vinyl monomer (B) contains 30 mol% or more of a monomer having two or more vinyl groups in the molecule. [2] The method for producing a copolymer according to [1], wherein the vinyl polymer (A) has a functional group containing an iodine atom. [3] The method for producing a copolymer according to [2], wherein the functional group containing an iodine atom is a group represented by the following formula (I).

[0008]

Chemical formula

[0009] (In formula (I), R 1 represents a hydrogen atom or a methyl group, and R 2 represents -OC(O)R<第 3 , -CONH2, -CN, -COOR<第 3 or an aryl group. R<第 3 represents an alkyl group or an aryl group.) [4] The method for producing a copolymer according to any one of [1] to [3], wherein the polymerization catalyst (C) is at least one selected from a compound having a nitrogen-containing functional group and an iodide salt. [5] The method for producing a copolymer according to any one of [1] to [4], wherein when the number average molecular weight of the copolymer is Mn and the weight average molecular weight is Mw, Mn is 100,000 or more and Mw / Mn is 1.1 to 3.0. [6] The method for producing a copolymer according to [5], wherein Mn is 250,000 or more. [7] The method for producing a copolymer according to any one of [1] to [6], wherein the average particle diameter of the copolymer determined by the dynamic light scattering method is 10 to 150 nm. [8] The method for producing a copolymer according to any one of [1] to [7], wherein the vinyl monomer (B) contains 30 mol% or more of a divinyl monomer or a trivinyl monomer. [9] The method for producing a copolymer according to any one of [1] to [8], wherein the vinyl monomer (B) contains 30 mol% or more of a divinyl monomer.

[10] A copolymer having three or more block polymer chains containing a block segment composed of a constitutional unit (a), wherein the constitutional unit (a) is a constitutional unit derived from a monomer having two or more vinyl groups in the molecule, and the block segment composed of the constitutional unit (a) forms a crosslinked structure at the center of the copolymer and has an iodine end in the crosslinked structure.

[11] The copolymer according to

[10] , wherein the block polymer chain has a main chain and a branched chain in at least one block segment, and the branched chain consists of the same constitutional unit as the constitutional unit of the main chain at the portion where the branching occurs. [Advantages of the Invention]

[0010] According to the present invention, a copolymer having a sufficiently large molecular weight and a small molecular weight distribution can be obtained by sufficiently controlling the molecular weight and the molecular weight distribution. [Embodiments for Carrying Out the Invention]

[0011] The embodiments for carrying out the present invention will be described in detail below, but the present invention is not limited to the following description and can be implemented in various ways within the scope of its gist.

[0012] [Explanation of terms] The following definitions of terms apply throughout this specification and the claims. "Constituent unit" refers to a constituent unit derived from a monomer, that is, a constituent unit formed by the polymerization of monomers, or a constituent unit in which a part of the constituent unit is transformed into a different structure by processing the polymer. A "vinyl monomer" refers to a compound that contains at least one vinyl group (carbon-carbon unsaturated double bond). "(Meth)acrylate" refers to either "acrylate" or "methacrylate." "(Meth)acrylonitrile" refers to either "acrylonitrile" or "methacrylonitrile". "(Meth)acrylic acid" refers to "acrylic acid" or "methacrylic acid." "(Meth)acryloyl" refers to either "acryloyl" or "methacryloyl".

[0013] [Method for producing copolymers] The method for producing a copolymer according to the present invention comprises the step of polymerizing a polymerizable composition containing a vinyl polymer (A), a vinyl monomer (B), and a polymerization catalyst (C). Furthermore, the vinyl polymer (A) has 0.8 to 2.9 iodine atoms in its molecule, and when the number average molecular weight of the vinyl polymer (A) is Mn(A), Mn(A) is 3,000 to 100,000, and the vinyl monomer (B) contains 30 mol% or more of monomers having two or more vinyl groups in its molecule.

[0014] <Polymerizable composition> The polymerizable composition comprises a vinyl polymer (A), a vinyl monomer (B), and a polymerization catalyst (C). The polymerizable composition may optionally contain a solvent and other additives. Each component is described in detail below.

[0015] ((Vinyl polymer (A)) The vinyl polymer (A) is a polymer having structural units derived from vinyl monomers and has 0.8 to 2.9 iodine atoms in the molecule. Thereby, a copolymer having a sufficiently large molecular weight and a small molecular weight distribution can be obtained. The lower limit of the number of iodine atoms is preferably 0.9 or more, and the upper limit is preferably 2.1 or less.

[0016] The number of iodine atoms that the vinyl polymer (A) has in the molecule is taken as the value obtained by the following formula (II), where x (%) is the ratio (mass%) of the total iodine atoms of the vinyl polymer (A) determined by elemental analysis, and y (g / mol) is the number average molecular weight Mn(A) of the vinyl polymer (A) determined by GPC measurement. The number of iodine atoms that the vinyl polymer (A) has in the molecule = (x / 126.9) × y / 100 ···(II)

[0017] The position of the iodine atoms in the vinyl polymer (A) is not particularly limited, but it is preferably included in the functional groups at the ends of the vinyl polymer (A). The functional group containing an iodine atom is not particularly limited, and examples thereof include a group represented by the following formula (I).

[0018]

Chemical formula

[0019] In formula (I), R 1 represents a hydrogen atom or a methyl group, and R 2 represents -OC(O)R 3 , -CONH2, -CN, -COOR 3 ​​​​​​​​​​​​​​​​Examples of alkyl groups include branched or linear alkyl groups having 1 to 20 carbon atoms. Specifically, examples include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, t-butyl group, i-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group.

[0021] R 3 Examples of aryl groups include aryl groups having 6 to 18 carbon atoms. Specifically, phenyl, benzyl, or naphthyl groups can be cited. Note R 3 The alkyl or aryl group may have substituents. Examples of substituents include alkyl groups, aryl groups, carboxyl groups, alkoxycarbonyl groups, carbamoyl groups, cyano groups, hydroxyl groups, amino groups, amide groups, halogen atoms, allyl groups, epoxy groups, alkoxy groups, and hydrophilic or ionic groups. Examples of hydrophilic or ionic groups include alkali salts of carboxyl groups or sulfoxyl groups, poly(alkylene oxide) groups such as polyethylene oxide groups and polypropylene oxide groups, and cationic substituents such as quaternary ammonium bases.

[0022] The Mn(A) of vinyl polymer (A) is between 3,000 and 100,000. A Mn(A) of 3,000 or higher improves the mechanical properties, particularly the elastic modulus, of the resulting copolymer. A Mn(A) of 100,000 or lower allows for a uniform increase in the molecular weight of the copolymer.

[0023] When the weight-average molecular weight of the vinyl polymer (A) is denoted as Mw(A), the ratio Mw(A) / Mn(A) is preferably between 1.0 and 3.0. This results in a copolymer with a small molecular weight distribution. Mn(A) and Mw(A) are calculated using gel permeation chromatography (GPC) from the calibration curve of polymethyl methacrylate (PMMA).

[0024] The vinyl polymer (A) may have one or more constituent units derived from vinyl monomers. Examples of vinyl monomers used in vinyl polymer (A) include styrene monomers, (meth)acrylate monomers, carboxyl group-containing vinyl monomers, acid anhydride group-containing vinyl monomers, amide group-containing vinyl monomers, (meth)acrylonitrile, vinyl chloride, vinyl acetate, vinyl propionate, and the like.

[0025] Examples of styrene monomers include styrene, α-methylstyrene, o-, m- or p-methylstyrene, o-, m- or p-methoxystyrene, o-, m- or pt-butoxystyrene, o-, m- or p-chloromethylstyrene, o-, m- or p-chlorostyrene, o-, m- or p-hydroxystyrene, o-, m- or p-styrenesulfonic acid and its derivatives, sodium o-, m- or p-styrenesulfonate, o-, m- or p-styreneboronic acid and its derivatives.

[0026] Examples of (meth)acrylate monomers include methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate, isoamyl(meth)acrylate, hexyl(meth)acrylate, octyl(meth)acrylate, lauryl(meth)acrylate, dodecyl(meth)acrylate, stearyl(meth)acrylate, phenyl(meth)acrylate, benzyl(meth)acrylate, glycidyl(meth)acrylate, glycidylα-ethylacrylate, 3,4-epoxybutyl(meth)acrylate, dimethylaminoethyl(meth)acrylate, diethylaminoethyl(meth)acrylate, 2-ethyl(meth)acrylate. Examples include hydroxyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 3-hydroxybutyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, polyethylene glycol(meth)acrylate and its alkyl ethers, polypropylene glycol(meth)acrylate and its alkyl ethers, methoxyethyl(meth)acrylate, ethoxyethyl(meth)acrylate, n-butoxyethyl(meth)acrylate, isobutoxyethyl(meth)acrylate, t-butoxyethyl(meth)acrylate, phenoxyethyl(meth)acrylate, nonylphenoxyethyl(meth)acrylate, 3-methoxybutyl(meth)acrylate, and the like.

[0027] Examples of carboxyl group-containing vinyl monomers include (meth)acrylic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleic acid, monomethyl itaconic acid, and the like.

[0028] Examples of vinyl monomers containing acid anhydride groups include maleic anhydride and itaconic anhydride. Examples of amide group-containing vinyl monomers include (meth)acrylamide, Nt-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone acrylamide, maleic acid amide, and maleimide.

[0029] From the viewpoint of availability, styrene, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol (meth)acrylate and its alkyl ether or methoxyethyl (meth)acrylate are preferred as vinyl monomers to be used in vinyl polymer (A).

[0030] The structural form of the vinyl polymer (A) is not particularly limited and includes linear polymers, AB block polymers, ABA block polymers, branched polymers, graft polymers, star polymers, and the like.

[0031] The content of vinyl polymer (A) in the polymerizable composition is arbitrary, but it is preferably 0.01 to 50 mol% relative to the total of vinyl polymer (A) and vinyl monomer (B). This increases the molecular weight of the resulting copolymer. The lower limit of the vinyl polymer (A) content is preferably 0.1 mol% or more, and the upper limit is preferably 30 mol% or less.

[0032] Vinyl polymer (A) can be produced by known methods, such as (reverse) iodine transfer polymerization ((R)ITP method), reversible transfer catalytic polymerization (RTCP method), and reversible complex formation-mediated polymerization (RCMP method). These polymerization methods can include, for example, aqueous dispersion polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization.

[0033] Specifically, a vinyl polymer (A) can be produced by polymerizing a polymethyl methacrylate (PMMA) macromonomer synthesized using a cobalt chain transfer agent (U.S. Patent No. 4680352) and n-butyl acrylate (BA) using the RCMP method. In this case, 2-iodo-2-cyanopropane (CP-I) may be used as a polymerization initiator, and tetra-n-butylammonium iodide (BNI) may be used as a polymerization catalyst. This makes it possible to produce a vinyl polymer (A) having one iodine atom in its molecule.

[0034] In addition to the methods described above, vinyl polymer (A) can also be produced by introducing iodine-containing functional groups into iodine-free vinyl polymers through chemical reactions such as end-to-end changes or end-to-end introductions. For example, PMMA containing one bromine atom can be produced by atom transfer radical polymerization (ATRP) and then reacted with sodium iodide to replace the bromine atom with an iodine atom.

[0035] (Vinyl monomer (B)) Vinyl monomer (B) contains 30 mol% or more of monomers having two or more vinyl groups in the molecule (hereinafter also referred to as "monomer (B1)"). This increases the molecular weight of the resulting copolymer. Preferably, vinyl monomer (B) contains 50 mol% or more of monomer (B1). Furthermore, vinyl monomer (B) preferably contains 30 mol% or more of divinyl monomer or trivinyl monomer, and more preferably contains 30 mol% or more of divinyl monomer.

[0036] Examples of monomers (B1) include divinylbenzene, dibromodivinbenzene, dimethoxydivinylbenzene, diethoxydivinylbenzene, dipropoxydivinylbenzene, dibutoxydivinylbenzene, dipentyloxydivinylbenzene, dihexyloxydivinylbenzene, diheptyloxydivinylbenzene, dioctyloxydivinylbenzene, dinonyloxydivinylbenzene, didedyloxydivinylbenzene, di(2-ethylhexyl)oxydivinylbenzene, ethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and diethylene glycol di(meth)acrylate. Examples include triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, allyl(meth)acrylate, N,N'-methylenebis(meth)acrylamide, glycerol tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, diurethane di(meth)acrylate, bis(2-methacryloyl)oxyethyl disulfide, bis(2-acryloyl)oxyethyl disulfide, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, etc.

[0037] From the viewpoint of availability, divinylbenzene, ethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate are preferred as monomers (B1). These may be used individually or in combination of two or more.

[0038] The vinyl monomer (B) may contain a monomer having one vinyl group in its molecule (hereinafter also referred to as "monomer (B2)"). Examples of monomer (B2) include the same vinyl monomer that gives the constituent units of the vinyl polymer (A) described above. These may be used individually or in combination of two or more.

[0039] From the viewpoint of polymerization control, monomer (B2) is preferably at least one selected from the group consisting of styrene monomers and (meth)acrylate monomers. Styrene is preferred as the styrene monomer. Preferred (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol (meth)acrylate and its alkyl ether or methoxyethyl (meth)acrylate.

[0040] The content of vinyl monomer (B) in the polymerizable composition is arbitrary, but it is preferably 50 to 99.99 mol% relative to the total amount of vinyl polymer (A) and vinyl monomer (B). This increases the molecular weight of the resulting copolymer. It is more preferable that the lower limit of the vinyl monomer (B) content is 70 mol% or more, and the upper limit is 99.9 mol% or less.

[0041] (Polymerization catalyst (C)) Polymerization catalyst (C) is used to abstract the iodine atom from the carbon-iodine bond in the vinyl polymer (A). The polymerizable composition containing polymerization catalyst (C) promotes the homogeneous dissociation reaction of the iodine atom from the carbon-iodine bond, thereby improving the polymerization rate. Polymerization catalyst (C) is preferably at least one selected from compounds having nitrogen-containing functional groups and iodide salts. Note that compounds having nitrogen-containing functional groups also include polymer compounds having nitrogen-containing functional groups.

[0042] Examples of compounds containing nitrogen-containing functional groups include trialkylamines (triethylamine, tributylamine, etc.), tetrakisdimethylaminoethene (TDAE), 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecanetributylphosphine (TDME), phthalimides, pyridines, bipyridines, N,N,N',N”,N”-pentamethyldiethylenetriamine (PMDETA), ethylenediamine, dimethylethylenediamine, tetramethylethylenediamine, tetramethyldiaminomethane, tris(2-aminoethyl)amine, tris(2-(methylamino)ethyl)amine, hematoporphyrin, and their derivatives; succinimide, 2,2-dimethylsuccinimide, α,α Examples include -dimethyl-β-methylsuccinimide, 3-ethyl-3-methyl-2,5-pyrrolidinidione, cis-1,2,3,6-tetrahydrophthalimide, α-methyl-α-propylsuccinimide, 5-methylhexahydroisoindole-1,3-dione, 2-phenylsuccinimide, α-methyl-α-phenylsuccinimide, 2,3-diacetoxysuccinimide, maleimide, phthalimide, 4-methylphthalimide, N-chlorophthalimide, N-bromophthalimide, 4-nitrophthalimide, 2,3-naphthalenecarboxyimide, pyromellidiimide, 5-bromoisoindole-1,3-dione, N-chlorosuccinimide, N-bromosuccinimide, and N-iodosuccinimide (NIS). Among these, triethylamine, tributylamine, TDAE, TDME, PMDETA, succinimide, phthalimide, N-chlorosuccinimide, N-bromosuccinimide, or NIS are preferred in terms of availability and solubility. These nitrogen-containing functional group compounds may be used individually or in combination of two or more.

[0043] Examples of iodide salts include imidazole salt compounds such as 1-methyl-3-methylimidazolium iodide (EMIZI) and 1-ethyl-3-methylimidazolium bromide (EMIZBr); pyridine salt compounds such as 2-chloro-1-methylpyridinium iodide (CMPI); quaternary amine salt compounds such as tetra-n-butylammonium iodide (BNI), tetra-n-butylammonium triiodide (BNI3), tetra-n-butylammonium bromodiodide (BNBrI2), and tetra-n-octylammonium iodide (ONI); and methyltributylphosphonium. Examples include phosphonium salt compounds such as iodide (BMPI); tetraphenylphosphonium iodide (PPI) and its derivatives; tributylsulfonium iodide (BSI) and its derivatives; diphenyliodonium iodide (PII); hexaphenyldiphosphazenium chloride (PPNCl) and its derivatives; alkali metal iodides such as sodium iodide, potassium iodide, and cesium iodide; and alkaline earth metal iodides such as magnesium iodide and calcium iodide. Among these, BNI, ONI, BNPI, sodium iodide, or potassium iodide are preferred due to their availability. These iodide salts may be used individually or in combination of two or more.

[0044] Furthermore, the polymerization catalyst (C) may include a radical polymerization initiator. This improves the polymerization rate of the copolymer. Examples of radical polymerization initiators include organic peroxides or azo compounds. Examples of organic peroxides include 2,4-dichlorobenzoyl peroxide, t-butyl peroxypivalate, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, t-butyl peroxy-2-ethylhexanoate, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, and di-t-butyl peroxide. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile). Among these, benzoyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile) are preferred. These radical polymerization initiators may be used alone or in combination of two or more.

[0045] The content of polymerization catalyst (C) in the polymerizable composition is preferably 0.1 to 2000 mmol per liter of polymerizable composition. This sufficiently improves the polymerization rate of the copolymer and allows for the production of a copolymer with a small molecular weight distribution. The lower limit of the content of polymerization catalyst (C) is preferably 0.5 mmol or more, and the upper limit is more preferably 1500 mmol or less.

[0046] When the polymerization catalyst (C) contains a radical polymerization initiator, the content of the radical polymerization initiator in the polymerizable composition is arbitrary, but it is preferably 0.001 to 0.05 moles per mole of vinyl monomer (A). This improves the polymerization rate of the copolymer. The lower limit of the radical polymerization initiator content is preferably 0.002 moles or more, and the upper limit is more preferably 0.02 moles or less.

[0047] (solvent) Examples of solvents include hydrocarbon solvents such as toluene; ether solvents such as diethyl ether, tetrahydrofuran, and diglyme; halogenated hydrocarbon solvents such as dichloromethane and chloroform; ketone solvents such as acetone; alcohol solvents such as methanol; nitrile solvents such as acetonitrile; vinyl ester solvents such as ethyl acetate; carbonate solvents such as ethylene carbonate; and supercritical carbon dioxide. These may be used individually or in combination of two or more. The solvent content in the polymerizable composition is preferably 20 to 90% by mass.

[0048] (Other additives) Other additives include, for example, chain transfer agents such as mercaptans and iodine.

[0049] <Polymerization of polymerizable compositions> The method for polymerizing the polymerizable composition is not particularly limited and includes methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Polymerization of polymerizable compositions may be carried out in the presence of air, but from the viewpoint of polymerization efficiency, it is preferable to carry out the polymerization under conditions in which the air is replaced with an inert gas such as nitrogen or argon.

[0050] The temperature of the polymerizable composition during polymerization is preferably 0 to 150°C, with a lower limit of 20°C or higher and a higher limit of 120°C or lower, from the viewpoint of polymerization rate and polymerization control. Furthermore, it is preferable to maintain the temperature of the polymerizable composition constant from the start of polymerization until the conversion rate of vinyl monomer (B) reaches 50%. This facilitates polymerization to proceed to the region where the conversion rate of vinyl monomer (B) is high. The temperature after the conversion rate of vinyl monomer (B) exceeds 50% is not particularly limited and may be further increased.

[0051] The polymerization time is not particularly limited, but is generally preferably 0.5 to 72 hours, and more preferably 0.5 to 60 hours.

[0052] [Copolymer] The copolymer produced by the copolymer production method according to the present invention has three or more block polymer chains, each containing a block segment made of a constituent unit (a). The constituent unit (a) is a constituent unit derived from a monomer (monomer (B1)) having two or more vinyl groups in its molecule, and the block segment made of the constituent unit (a) forms a crosslinked structure in the center of the copolymer, with an iodine terminus in the crosslinked structure. In this specification, the block segment located at the center of the copolymer is also referred to as the core structure, and the block segments connected to the core structure are also referred to as the arm structure. A copolymer having such a core structure and arm structure is also referred to as a star polymer. In the copolymer according to the present invention, the core structure has a crosslinked structure formed by block segments consisting of the aforementioned constituent unit (a). The arm structure consists of block segments that do not contain the aforementioned constituent unit (a), and three or more arm structures are connected to the core structure to form a star polymer.

[0053] Furthermore, the block polymer chains of the copolymer may have a main chain and branched chains within at least one block segment. In this case, it is preferable that the branched chains consist of the same structural units as the main chain in the portion where the branching occurs.

[0054] The branched structure of the copolymer can be confirmed by GPC-TDA measurement using a viscometer or GPC-MALS measurement using a multi-angle light scattering detector. Unreacted vinyl groups in the crosslinked structure can be identified by NMR measurement. The presence of iodine atoms can be confirmed by elemental analysis, and the location of iodine atoms can be determined by X-ray photoelectron spectroscopy (XPS) measurement of a section of the copolymer. The copolymer according to the present invention allows for the decomposition of the crosslinked structure formed in the center of the copolymer by a hydrolysis reaction or a transesterification reaction, and allows for the recovery of only the polymer corresponding to the arm structure of the copolymer. The structure of the recovered polymer can be identified by NMR measurement to determine the unreacted vinyl groups in the crosslinked structure that were present in the core structure of the copolymer before the decomposition reaction was carried out. Similarly, if the block polymer chains of the copolymer have a main chain and branched chains within at least one block segment, and the branched chains consist of the same constituent units as the main chain at the point where branching occurs, the polymer recovered by the decomposition reaction of the copolymer can also be identified by NMR measurement. These findings allow us to confirm the structure of the copolymer produced by the copolymer production method according to the present invention.

[0055] The copolymer produced by the copolymer production method according to the present invention preferably has a number-average molecular weight of 100,000 or more and a weight-average molecular weight of 1.1 to 3.0, where Mn is 100,000 or more and Mw / Mn is 1.1 to 3.0. This improves the mechanical properties, particularly the elastic modulus, of the resulting copolymer. The Mn of the copolymer is more preferably 200,000 or more, and even more preferably 250,000 or more. The Mw / Mn of the copolymer is more preferably 1.1 to 2.5.

[0056] The average particle size of the copolymer, as determined by dynamic light scattering (DLS) method, is preferably 10 to 150 nm. This reduces light scattering when the copolymer is used as an additive.

[0057] The applications of the copolymer according to the present invention are not particularly limited and include, for example, dispersants, resin additives, paint compositions, and polymers for lithography. [Examples]

[0058] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following description.

[0059] [Number of iodine atoms in the molecule of vinyl polymer (A)] The number of iodine atoms contained within the vinyl polymer (A) was determined by the following formula (II), where x (%) is the total percentage (mass%) of iodine atoms in vinyl polymer (A) determined by elemental analysis, and y (g / mol) is the number-average molecular weight Mn(A) of vinyl polymer (A) determined by GPC measurement. The number of iodine atoms in the molecule of vinyl polymer (A) = (x / 126.9) × y / 100 ... (II) The GPC measurement conditions were as follows: Column: TSK GUARD COLUMN SUPER HZ-L (4.6mm x 35mm) and TSK-GEL SUPER HZM-N (6.0mm x 150mm) connected in series. Measuring device: Tosoh Corporation "HLC-8220", Eluent: Tetrahydrofuran (THF), Measurement temperature: 40℃, Flow rate: 0.6mL / min.

[0060] [Number-average molecular weight and weight-average molecular weight] The number-average molecular weight (Mn(A)) and weight-average molecular weight (Mw(A)) of the vinyl polymer (A), and the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the copolymer were calculated from the PMMA calibration curve using GPC. The GPC was measured under the same conditions as described above.

[0061] [Conversion rate of monomers] The conversion rate of each monomer was calculated as the ratio of the amount of polymer produced to the sum of the amount of residual monomer and the amount of polymer produced, using an NMR analyzer (Bruker, "BBF0400", 400 MHz).

[0062] [Conversion rate of vinyl polymer (A)] The conversion rate of vinyl polymer (A) was calculated by determining the peak area of ​​vinyl polymer (A) before and after polymerization using GPC measurement, and then calculating the rate of decrease in the peak area after polymerization. The GPC was measured under the same conditions as described above.

[0063] [Average particle size of copolymer] The average particle size of the copolymer was measured by dynamic light scattering (DLS) using a light scattering instrument (Malvern Panalytical, "Zetasizer Nano ZSP"). DLS measurements were performed at room temperature with a measurement angle of 173° on a solution prepared by dissolving 5 mg of solid sample in 2 mL of THF. The average particle size was defined as the particle size at the highest frequency on the obtained particle size distribution curve.

[0064] [Abbreviation] The abbreviations used in this embodiment are as follows:

[0065] <Vinyl monomer (B)> BA: n-butyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) BMA: n-butyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) St: Styrene (manufactured by Tokyo Chemical Industry Co., Ltd.) LA: Lauryl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) AN: Acrylonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) PEGA: Polyethylene glycol acrylate (manufacturer unknown) EGDMA: Ethylene glycol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) DGDA: Diethylene glycol diacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0066] <Polymerization catalyst (C)> BNI: Tetra-n-butylammonium iodide (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0067] <Polymerization initiator> CP-I: 2-iodine-2-cyanopropane (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0068] <Macromonomers> PMMA-MM: Polymethyl methacrylate macromonomer (manufactured by Mitsubishi Chemical Corporation, Mn=3,800)

[0069] [Synthesis Example 1] BA and PMMA-MM were mixed using CP-I as a polymerization initiator and BNI as a polymerization catalyst to obtain the composition shown in Table 1. The resulting mixture was then transferred to a glass reaction vessel, the gas phase was replaced with argon gas, and the polymerization temperature was raised to 110°C while stirring. The reaction was carried out for the polymerization time shown in Table 1, and then reprecipitation was performed using a mixed solvent of methanol and water in a weight ratio of 7:3 as a poor solvent to obtain vinyl polymer (A1). The number of iodine atoms in the molecule of the obtained vinyl polymer (A1), Mn(A), and Mw(A) / Mn(A) are shown in Table 1. The vinyl polymer (A1) has a functional group containing an iodine atom, as R in formula (I). 1 is a hydrogen atom, and R 2 ga-COOR 3 And R 3 It has a group at its terminal end that is an n-butyl group.

[0070] [Synthesis Examples 2-4] Vinyl polymers (A2) to (A4) were obtained by the same method as in Synthesis Example 1, except that the compositions of BA, PMMA-MM, CP-I, and BNI, and the polymerization time were changed as shown in Table 1. The number of iodine atoms, Mn(A), and Mw(A) / Mn(A) of the obtained vinyl polymers (A2) to (A4) are shown in Table 1. The vinyl polymers (A2) to (A4) have iodine atoms as functional groups, and R in formula (I) 1 is a hydrogen atom, and R 2 ga-COOR 3 And R 3 It has a group at its terminal end that is an n-butyl group.

[0071] [Synthesis Examples 5-8] Vinyl polymers (A5) to (A8) were obtained in the same manner as in Synthesis Example 1, except that the type and content of vinyl monomer, CP-I, BNI, and solvent, the use of 2,2'-azobis(isobutylnitrile) (AIBN), polymerization temperature, and polymerization time were changed as shown in Table 1. The number of iodine atoms, Mn(A), and Mw(A) / Mn(A) of the obtained vinyl polymers (A5) to (A8) are shown in Table 1. The vinyl polymer (A5) has a functional group containing an iodine atom, R in formula (I). 1 is a hydrogen atom, and R 2 The group has a phenyl group at its terminal end. The vinyl polymer (A6) has a functional group containing an iodine atom, as in formula (I) R 1 is a hydrogen atom, and R 2 ga-COOR 3 And R 3 The group has an n-lauryl group at its terminal end. The vinyl polymer (A7) has a functional group containing an iodine atom, as in formula (I) R 1 is a hydrogen atom, and R 2 The group has a -CN group at its terminal end. The vinyl polymer (A8) has a functional group containing an iodine atom, as in formula (I) R 1 is a methyl group, R 2 ga-COOR 3 And R 3It has a methyl group at its terminal end.

[0072] [Synthesis Example 9] Vinyl polymer (A9) was obtained in the same manner as in Synthesis Example 1, except that vinyl polymer (A8) synthesized in Synthesis Example 8 was used as the polymerization initiator, and the types and contents of monomers, CP-I, and BNI were changed as shown in Table 1. The number of iodine atoms, Mn(A), and Mw(A) / Mn(A) of the obtained vinyl polymer (A9) are shown in Table 1. The vinyl polymer (A9) has a functional group containing an iodine atom, as shown in formula (I) R 1 is a hydrogen atom, and R 2 It has a group at its terminal end that is a polyethylene glycol group.

[0073] In Table 1, "eq" indicates "molar equivalents". The columns [Vinyl Monomer] / [PMMA-MM] / [Polymerization Initiator] / [BNI] / [AIBN] show the molar equivalents of vinyl monomer, PMMA-MM, polymerization initiator (CP-I or vinyl polymer (A8)), BNI, and AIBN in the mixture used for polymerization of vinyl polymer (A).

[0074] [Table 1]

[0075] [Example 1] A polymerizable composition was prepared using the vinyl polymer (A1) obtained in Synthesis Example 1 as the vinyl polymer (A), EGDMA as the vinyl monomer (B), BNI as the polymerization catalyst (C), and butyl acetate as the solvent, with the composition shown in Table 2. In Table 2, "eq" indicates the number of molar equivalents. The obtained polymerizable composition was transferred to a glass reaction vessel, the gas phase was replaced with argon gas, and polymerization was carried out with stirring at a polymerization temperature of 110°C for 24 hours to obtain a copolymer. The Mn, Mw / Mn, and average particle size of the obtained copolymer are shown in Table 3. In Table 3, the solvent content represents the amount of solvent (mass%) when the total amount including the solvent is taken as 100% by mass. Furthermore, the copolymer is a copolymer having three or more block polymer chains, each containing a block segment made of a constituent unit (a), wherein the block segment made of the constituent unit (a) forms a crosslinked structure in the center of the copolymer, and the crosslinked structure has an iodine terminus.

[0076] [Examples 2-16] Copolymers were obtained in the same manner as in Example 1, except that the type and content of the vinyl polymer (A), vinyl monomer (B), polymerization catalyst (C), and solvent, as well as the polymerization time, were changed as shown in Table 2. The Mn, Mw / Mn, and average particle size of the obtained copolymers are shown in Table 3. Furthermore, the copolymer is a copolymer having three or more block polymer chains, each containing a block segment made of a constituent unit (a), wherein the block segment made of a constituent unit (a) forms a crosslinked structure in the center of the copolymer, and the crosslinked structure has an iodine terminus. In addition, the copolymers obtained in Examples 6 to 10 and 12 have a main chain and a branched chain within at least one block segment, and the branched chain consists of the same constituent units as the main chain in the portion where the branching occurs.

[0077] [Comparative Example 1] A polymerizable composition was prepared using PMMA-MM, which does not contain iodine atoms in its molecule, instead of vinyl polymer (A). BA was used as the vinyl monomer (B), and BNI and CP-I were used as polymerization catalysts (C) in the compositions shown in Table 2. The obtained polymerizable composition was transferred to a glass reaction vessel, the gas phase was replaced with argon gas, and polymerization was carried out with stirring at a polymerization temperature of 110°C for 24 hours to obtain a copolymer. The Mn, Mw / Mn, and average particle size of the obtained copolymer are shown in Table 3.

[0078] [Comparative Example 2] A copolymer was obtained using the same method as in Comparative Example 1, except that the type and content of vinyl monomer (B) were changed as shown in Table 2. The obtained copolymer was gelled, and it was not possible to evaluate Mn, Mw / Mn, and average particle size.

[0079] [Comparative Examples 3-4] Copolymers were obtained in the same manner as in Example 1, except that the type and content of the vinyl polymer (A), vinyl monomer (B), polymerization catalyst (C), and solvent, as well as the polymerization time, were changed as shown in Table 2. The Mn, Mw / Mn, and average particle size of the obtained copolymers are shown in Table 3.

[0080] [Table 2]

[0081] [Table 3]

[0082] As shown in Table 3, in Examples 1 to 16, in which polymerizable compositions containing a predetermined vinyl polymer (A), vinyl monomer (B), and polymerization catalyst (C) were polymerized, copolymers with sufficiently large molecular weights and a small molecular weight distribution were obtained in all cases.

[0083] On the other hand, in Comparative Example 1, which used PMMA-MM that does not contain iodine atoms in its molecule instead of vinyl polymer (A), and in Comparative Examples 3 and 4, where the proportion of monomer (B1) in vinyl monomer (B) was smaller than the specified value, the molecular weight of the resulting copolymer was smaller compared to the example. Furthermore, in Comparative Example 2, which used PMMA-MM that does not contain iodine atoms in its molecule instead of vinyl polymer (A) and where the proportion of monomer (B1) in vinyl monomer (B) was smaller than the specified value, the resulting copolymer gelled.

Claims

1. A method for producing a copolymer, comprising the step of polymerizing a polymerizable composition containing a vinyl polymer (A), a vinyl monomer (B), and a polymerization catalyst (C) (excluding a radical polymerization initiator), The polymerization catalyst (C) is at least one selected from compounds having nitrogen-containing functional groups and iodide salts. The vinyl polymer (A) has 0.8 to 2.9 iodine atoms in its molecule, and when the number-average molecular weight of the vinyl polymer (A) is Mn(A), Mn(A) is 3,000 to 100,000. A method for producing a copolymer, wherein the vinyl monomer (B) contains 30 mol% or more of a monomer having two or more vinyl groups in its molecule.

2. The method for producing the copolymer according to claim 1, wherein the vinyl polymer (A) has a functional group containing an iodine atom.

3. The method for producing a copolymer according to claim 2, wherein the functional group containing the iodine atom is a group represented by the following formula (I). 【Chemistry 1】 (In formula (I), R １ R represents a hydrogen atom or a methyl group. ２ Ha-OC(O)R ３ , -CONH ２ , -CN, -COOR ３ Alternatively, it represents an aryl group. R ３ (This represents an alkyl group or aryl group.)

4. A method for producing a copolymer according to any one of claims 1 to 3, wherein, when the number average molecular weight of the copolymer is Mn and the weight average molecular weight is Mw, Mn is 100,000 or more and Mw / Mn is 1.1 to 3.

0.

5. The method for producing the copolymer according to claim 4, wherein the Mn is 250,000 or more.

6. A method for producing the copolymer according to any one of claims 1 to 5, wherein the average particle size of the copolymer, as determined by dynamic light scattering, is 10 to 150 nm.

7. A method for producing a copolymer according to any one of claims 1 to 6, wherein the vinyl monomer (B) contains 30 mol% or more of a divinyl monomer or a trivinyl monomer.

8. A method for producing a copolymer according to any one of claims 1 to 7, wherein the vinyl monomer (B) contains 30 mol% or more of a divinyl monomer.

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