JP7672121B2 - Method for producing polymer using disulfide compound - Google Patents

Description

The present invention relates to a method for producing a polymer using a disulfide compound. More specifically, the present invention relates to a method for producing a polymer of a desired molecular weight by using a sequential feeding method in which a specific disulfide compound is pretreated with a radical initiator and then polymerized by adding a monomer.

It is known that disulfide compounds can be used as reversible addition-fragmentation chain transfer (RAFT) agents (Patent Documents 1 and 2). Polymerization methods using RAFT agents are living radical polymerizations, and are characterized by the fact that they are easy to control the number-average molecular weight and weight-average molecular weight, and produce polymers with narrow molecular weight distributions. However, in the polymerization methods described in prior art documents in which disulfide compounds are used as RAFT agents (herein referred to as the batch-feed method), polymers are obtained that have a designed molecular weight determined by the molar ratio of the monomer and the RAFT agent, i.e., a molecular weight that is about twice the desired molecular weight, and there is a problem that the disulfide compounds do not function sufficiently as polymerization control agents (Non-Patent Document 1).

International Publication No. WO1999/05099 Patent Application No. 2007-235324

Polymer Preprints, Japan Vol. 64, No. 2 (2015)

The objective of the present invention is to provide a production method for obtaining a polymer having a designed molecular weight, i.e., a desired molecular weight, determined by the molar ratio of monomer and RAFT agent, in a polymerization method using a disulfide compound as a RAFT agent.

As a result of intensive research, the inventors discovered that a polymer having a designed molecular weight determined by the molar ratio of monomer and RAFT agent, that is, a desired molecular weight, can be obtained by a polymer production method using a disulfide compound pretreated with a radical initiator as a polymerization control agent, and thus completed the present invention.

［式中、Ｒ_１およびＲ_２は相互に独立して、置換または無置換の芳香族炭化水素基、または式：－Ｓ－Ｘ－Ａ（ここで、Ｘは、可能な場合は酸素原子がアルキレン基の炭素結合の間に存在してもよい炭素数１～２０の置換または無置換の直鎖状または分枝鎖状のアルキレン基、または置換または無置換の炭素数３～１２の環状アルキレン基を表し、Ａは、水素、アルキルアミノ基、エステル基、ビニル基、または置換または無置換の芳香族炭化水素基を表す）を表す]
で表されるジスルフィド化合物をラジカル開始剤であらかじめ溶媒中または無溶媒中で処理した後、その処理物に少なくとも１種のラジカル重合性単量体を加えてラジカル重合させる重合体の製造方法が提供される。 Thus, according to the present invention, a compound represented by the general formula (1):

[In the formula, R ₁ and R ₂ each independently represent a substituted or unsubstituted aromatic hydrocarbon group, or a group represented by the formula: -S-X-A (wherein X represents a substituted or unsubstituted linear or branched alkylene group having 1 to 20 carbon atoms in which an oxygen atom may be present between the carbon bonds of the alkylene group, if possible, or a substituted or unsubstituted cyclic alkylene group having 3 to 12 carbon atoms, and A represents a hydrogen atom, an alkylamino group, an ester group, a vinyl group, or a substituted or unsubstituted aromatic hydrocarbon group)]
The present invention provides a method for producing a polymer, comprising treating a disulfide compound represented by the following formula (I) with a radical initiator in a solvent or without a solvent, and then adding at least one radically polymerizable monomer to the treated product to carry out radical polymerization.

The present invention also provides a method for producing a polymer, which comprises pretreating 0.1 to 50 parts by mass of a disulfide compound with 0.1 to 50 parts by mass of a radical initiator with 1 to 200 parts by mass of a solvent, at a temperature of -20 to 200°C, and for a treatment time of 0.1 to 100 hours, and then adding at least one radical polymerizable monomer to the treated product and radically polymerizing the product at a polymerization temperature of 5 to 200°C and for a polymerization time of 0.1 to 100 hours, to obtain a polymer having a number average molecular weight Mn of 500 to 1,000,000, a ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw/Mn) of 1.0 to 5.0, and a ratio of the number average molecular weight Mn to the design molecular weight M(th) (Mn/M(th)) of 0.7 to 1.3.

The present invention also provides a method for producing the above-mentioned polymer, which uses two or more types of radically polymerizable monomers to obtain a random copolymer or a block copolymer.

According to the present invention, a polymer having a desired molecular weight can be provided by pretreating a disulfide compound with a radical initiator and then polymerizing a radically polymerizable monomer.

The present invention will be described in detail below.

［式中、Ｒ_１およびＲ_２は相互に独立して、置換または無置換の芳香族炭化水素基、または式：－Ｓ－Ｘ－Ａ（ここで、Ｘは、可能な場合は酸素原子がアルキレン基の炭素結合の間に存在してもよい炭素数１～２０の置換または無置換の直鎖状または分枝鎖状のアルキレン基、または置換または無置換の炭素数３～１２の環状アルキレン基を表し、Ａは、水素、アルキルアミノ基、エステル基、ビニル基、または置換または無置換の芳香族炭化水素基を表す）を表す]
で表されるジスルフィド化合物をラジカル開始剤であらかじめ溶媒中または無溶媒中で処理した後、その処理物に少なくとも１種のラジカル重合性単量体を加えてラジカル重合させて重合体を製造することを特徴とする。 The production method of the present invention comprises the steps of:

[In the formula, R ₁ and R ₂ each independently represent a substituted or unsubstituted aromatic hydrocarbon group, or a group represented by the formula: -S-X-A (wherein X represents a substituted or unsubstituted linear or branched alkylene group having 1 to 20 carbon atoms in which an oxygen atom may be present between the carbon bonds of the alkylene group, if possible, or a substituted or unsubstituted cyclic alkylene group having 3 to 12 carbon atoms, and A represents a hydrogen atom, an alkylamino group, an ester group, a vinyl group, or a substituted or unsubstituted aromatic hydrocarbon group)]
The present invention is characterized in that a disulfide compound represented by the formula (I) is previously treated with a radical initiator in a solvent or without a solvent, and then at least one radically polymerizable monomer is added to the treated product to carry out radical polymerization to produce a polymer.

The phrase "treating a disulfide compound with a radical initiator in advance in a solvent or without a solvent, and then adding at least one type of radical polymerizable monomer to the treated product to polymerize" has the same meaning as "reacting a disulfide compound with a radical initiator in advance in a solvent or without a solvent, and then adding at least one type of radical polymerizable monomer to polymerize."

In the present invention, the "aromatic hydrocarbon group" is a monovalent aromatic hydrocarbon group, and suitable examples thereof include, but are not limited to, phenyl, naphthyl, anthryl, and phenanthryl, with phenyl being more preferred. These may be substituted with an appropriate substituent (e.g., alkyl, alkoxy, halogen, etc.).

Preferable examples of the "straight-chain or branched alkylene group having 1 to 20 carbon atoms" in the present invention include methylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, undecamethylene, dodecamethylene, tridecamethylene, tetradecamethylene, pentadecamethylene, hexadecamethylene, heptadecamethylene, octadecamethylene, nonadecamethylene, icosamethylene, ethylethylene, and dimethylethylene, with methylene, ethylene, and dodecamethylene being more preferable. These may be substituted with an appropriate substituent (e.g., alkoxy, halogen, etc.).

In the term "a straight-chain or branched-chain alkylene group having 1 to 20 carbon atoms in which an oxygen atom may be present between carbon bonds of the alkylene group, if possible," the alkylene group has 2 to 20 carbon atoms in the case where an oxygen atom is present between carbon bonds of the alkylene group.
Therefore, suitable examples of "straight-chain or branched-chain alkylene groups having 2 to 20 carbon atoms in which an oxygen atom is present between the carbon bonds of the alkylene groups" include, but are not limited to, diethylene oxide, di(trimethylene) oxide, dipropylene oxide, di(tetramethylene) oxide, di(pentamethylene) oxide, di(hexamethylene) oxide, di(heptamethylene) oxide, di(octamethylene) oxide, di(nonamethylene) oxide, di(decamethylene) oxide, ethylenemethylene oxide, triethylenedioxide, tripropylenedioxide, tri(trimethylene)dioxide, tetraethylenetrioxide, tetrapropylenetrioxide, pentaethylenetetraoxide, and hexaethylenepentoxide, with ethylenemethyleneoxide being more preferred. These may be substituted with an appropriate substituent (e.g., alkoxy, halogen, etc.).

Suitable examples of the "cyclic alkylene group having 3 to 12 carbon atoms" in the present invention include, but are not limited to, cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptalene, and decahydronaphthylene, which may be substituted with an appropriate substituent (e.g., alkoxy, halogen, etc.).

Suitable examples of alkyl in the suitable substituents include, but are not limited to, linear or branched alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, and hexyl.

Suitable examples of alkoxy in the suitable substituents include, but are not limited to, linear or branched alkyloxy groups having 1 to 6 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, pentyloxy, and hexyloxy.

Halogen in the suitable substituents above includes fluorine, chlorine, bromine and iodine.

Suitable examples of "straight-chain or branched-chain alkyl groups having 1 to 20 carbon atoms" in the present invention include, but are not limited to, straight-chain alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl, as well as branched-chain alkyl groups that are structural isomers of these.

The "alkylamino group" in the present invention includes an amino group mono- or di-substituted with a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms, where the alkyl groups in the dialkyl may be the same or different.
Preferred examples of the "alkylamino group" include, but are not limited to, methylamino, ethylamino, propylamino, isopropylamino, butylamino, pentylamino, neopentylamino, hexylamino, heptylamino, octylamino, nonylamino, decylamino, dimethylamino, diethylamino, dipropylamino, diisopropylamino, dibutylamino, dipentylamino, dineopentylamino, dihexylamino, diheptylamino, dioctylamino, dinonylamino, didecylamino, ethylmethylamino, methylpropylamino, and ethylpropylamino, and among these, diethylamino is more preferred.

In the present invention, the "ester group" is represented by -COOR', where R' is the above-mentioned linear or branched alkyl group having 1 to 20 carbon atoms. Among the alkyl groups, methyl, ethyl, propyl and butyl are preferred, and butyl is more preferred.

Radically polymerizable monomers that can be used in the method for producing a polymer of the present invention can be selected from substituted or unsubstituted styrene, substituted or unsubstituted alkyl acrylate, substituted or unsubstituted alkyl methacrylate, acrylonitrile, N-alkyl alkyl amide, N-alkyl methacrylamide, N,N-dialkyl acrylamide, N,N-dialkyl methacrylamide, isoprene, butadiene, ethylene, vinyl acetate, and combinations thereof.

Specific examples of radical polymerizable monomers include methyl methacrylate, ethyl methacrylate, propyl methacrylate (including all isomers), butyl methacrylate (including all isomers), 2-ethylhexyl methacrylate, isobornyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, α-methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate (including all isomers), butyl acrylate (including all isomers), 2-ethylhexyl acrylate, isobornyl acrylate, acrylic acid, benzyl acrylate, phenyl acrylate, and acrylonitrile. styrene, glycidyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate (including all isomers), hydroxybutyl methacrylate (including all isomers), N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, triethylene glycol methacrylate, itaconic anhydride, itaconic acid, glycidyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate (including all isomers), hydroxybutyl acrylate (including all isomers), N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, triethylene glycol methacrylate, triethylene glycol acrylate, methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide, N-t-butyl methacrylamide, N-n-butyl methacrylamide, N-methylolacrylamide, N-ethylolacrylamide, 4-acryloylmorpholine, vinylbenzoic acid (including all isomers), diethylaminostyrene (including all isomers), α-methylvinylbenzoic acid (including all isomers), diethylamino α-methylstyrene (including all isomers), p-vinylbenzenesulfonic acid, p-vinylbenzenesulfonic acid sodium salt, trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate Examples of the acrylate include, but are not limited to, tributoxysilylpropyl methacrylate, dimethoxymethylsilylpropyl methacrylate, diethoxymethylsilylpropyl methacrylate, dibutoxymethylsilylpropyl methacrylate, diisopropoxymethylsilylpropyl methacrylate, dimethoxysilylpropyl methacrylate, diethoxysilylpropyl methacrylate, dibutoxysilylpropyl methacrylate, diisopropoxysilylpropyl methacrylate, trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, tributoxysilylpropyl acrylate, diisopropoxysilylpropyl acrylate, maleic anhydride, N-phenylmaleimide, N-butylmaleimide, butadiene, isoprene, chloroprene, ethylene, vinyl acetate, and combinations thereof.

Preferred radical polymerizable monomers in the method for producing a polymer of the present invention include those selected from substituted or unsubstituted styrene, substituted or unsubstituted alkyl acrylate, substituted or unsubstituted alkyl methacrylate, N-alkyl acrylamide, N-alkyl methacrylamide, N,N-dialkyl acrylamide, N,N-dialkyl methacrylamide, and combinations thereof.

In the method for producing a polymer of the present invention, homopolymers, random copolymers, and block copolymers can be produced by controlling the type and addition method of the radical polymerizable monomer.

In the method for producing a polymer of the present invention, a solvent may be further added. Examples of the solvent used in the polymerization include alcohols (alkyl alcohols such as ethanol, propanol, isopropanol, butanol, and isobutanol, glycols such as ethylene glycol and propylene glycol, etc.), hydrocarbons (aliphatic hydrocarbons such as hexane, alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as toluene and xylene, etc.), halogenated hydrocarbons (methylene chloride, chloroform, etc.), ethers (chain ethers such as dimethyl ether and diethyl ether, cyclic ethers such as dioxane and tetrahydrofuran, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, ethyl butyrate, etc.), ketones (acetone, ethyl methyl ketone, methyl isobutyl ketone, cyclohexanone, N-methyl-2-pyrrolidone, etc.), cellosolves (methyl cellosolve, ethyl ... Examples of organic solvents include organic solvents such as methyl carbitol, ethyl carbitol, butyl carbitol, propylene glycol monoalkyl ethers (propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono n-butyl ether, etc.), glycol ether esters (ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, butyl carbitol acetate, etc.), amides (N,N-dimethylformamide, N,N-dimethylacetamide, etc.), sulfoxides (dimethyl sulfoxide, etc.), nitriles (acetonitrile, benzonitrile, etc.), and N-methylpyrrolidone. The organic solvent can be used alone or as a mixed solvent. From the viewpoint of the solubility of the disulfide compound, toluene, ethyl acetate, and tetrahydrofuran are preferred.

In the process for producing the polymer of the present invention, a radical initiator is an essential component.
The radical initiator is not particularly limited, and various types can be used. The radical initiator may be a thermal polymerization initiator (thermal radical generator) or a photopolymerization initiator (photoradical generator).

Thermal polymerization initiators (thermal radical generators) include organic peroxides such as dialkyl peroxides (di-t-butyl peroxide, dicumyl peroxide, etc.), diacyl peroxides [dialkanoyl peroxides (lauroyl peroxide, etc.), diaroyl peroxides (benzoyl peroxide, benzoyl toluyl peroxide, toluyl peroxide, etc.)], peroxyesters [percarboxylic acid alkyl esters such as t-butyl peracetate, t-butyl peroxy octoate, t-butyl peroxy benzoate, etc.], ketone peroxides, peroxycarbonates, and peroxyketals; azonitrile compounds or azo compounds [2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methyl ... Bis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 1,1'-azobis(cyclohexane-1-carbonitrile), 4,4'-azobis(4-cyanovaleric acid), etc.], azoamide compounds {2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, etc.}, azoamidine compounds Examples of the thermal polymerization initiator include azo compounds such as {2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, etc.}, azoalkane compounds [2,2'-azobis(2,4,4-trimethylpentane), 4,4'-azobis(4-cyanopentanoic acid), etc.], and azo compounds having an oxime skeleton [2,2'-azobis(2-methylpropionamidoxime), etc.]. The thermal polymerization initiator may be used alone or in combination of two or more kinds.

Examples of photopolymerization initiators (photoradical generators) include benzoins (benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether); acetophenones (acetophenone, p-dimethylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-phenyl-2-hydroxy-acetophenone, 1,1-dichloroacetophenone, and 1-hydroxycyclohexyl phenyl ketone); propiophenones (p-dimethylaminopropiophenone, 2-hydroxy-2-methyl-propiophenone, and 2,2-dimethoxy-1,2-diphenylethane-1-one); butyrylphenones [1-[4- (2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methyl-propan-1-one, etc.]; aminoacetophenones [2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-dimethylamino-2-methyl-1-phenylpropan-1-one, 2-diethylamino-2-methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino-1-phenylpropan-1-one, 2-dimethylamino-2-methyl-1-(4-methylphenyl)propan-1-one, 1-(4-butylphenyl)-2-dimethyl 2-methylamino-2-methylpropan-1-one, 2-dimethylamino-1-(4-methoxyphenyl)-2-methylpropan-1-one, 2-dimethylamino-2-methyl-1-(4-methylthiophenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-dimethylaminophenyl)-butan-1-one, etc.; benzophenones (benzophenone, N,N'-bis(dimethylamino)benzophenone (Michler's ketone), 3,3-dimethyl-4-methoxybenzophenone, N,N'-dialkylaminobenzophenones such as benzyl); ketals (acetophenone dimethyl ketal, benzyl dimethyl ketal, etc.); thioxanthenes (thioxanthene, 2-chlorothioxanthene, 2,4-diethylthioxanthene, etc.); anthraquinones (2-ethylanthraquinone, 1-chloroanthraquinone, 1,2-benzanthraquinone, 2,3-diphenylanthraquinone, etc.); (Thio)xanthones (thioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, etc.); acridines (1,3-bis-(9-acridinyl)propane, 1,7-bis-(9-acridinyl)heptane, 1,5-bis-(9-acridinyl)pentane, etc.); triazines (2,4,6-tris(trichloromethyl)-s-tolylthioxanthone, etc.); Examples include triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis-trichloromethyl-6-(3-bromo-4-methoxy)styrylphenyl-s-triazine, etc.; sulfides (benzyl diphenyl sulfide, etc.); acylphosphine oxides (2,4,6-trimethylbenzoyldiphenylphosphine oxide, etc.); titanocene photopolymerization initiators; oxime esters, etc. These photopolymerization initiators can be used alone or in combination of two or more.

In terms of polymerization temperature, 2,2'-azobis(isobutyronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 1,1'-azobis(cyclohexane-1-carbonitrile), and 4,4'-azobis(4-cyanovaleric acid) are preferred.

The composition of the present invention may contain various additives, if necessary. Examples of additives include thermal polymerization inhibitors (hydroquinone, hydroquinone monoethyl ether, etc.), defoamers, coatability improvers, thickeners, lubricants, stabilizers (antioxidants, heat stabilizers, light resistance stabilizers, etc.), plasticizers, surfactants, dissolution promoters, colorants, fillers, antistatic agents, silane coupling agents, leveling agents, dispersants, dispersion aids, etc. The additives may be used alone or in combination of two or more.

The production conditions of the production method of the present invention for producing a polymer, which comprises treating the disulfide compound of the formula (1) with a radical initiator in advance in a solvent or without a solvent, and then adding at least one kind of radically polymerizable monomer to the treated product to carry out radical polymerization, will be described.
All treatments and polymerizations are preferably carried out under an inert gas atmosphere (eg, nitrogen, etc.).

The conditions for treating the disulfide compound with a radical initiator are as follows.
The disulfide compound is used in an amount of preferably 0.1 to 50 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the radical polymerizable monomer.

When a solvent is used, the solvent is preferably used in an amount of 1 to 200 parts by mass, more preferably 30 to 100 parts by mass, based on 100 parts by mass of the radical polymerizable monomer. The radical initiator is preferably used in an amount of 0.1 to 50 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the radical polymerizable monomer.
In this treatment, the radical initiator may be used in excess, in which case the excess radical initiator may act as a radical polymerization initiator in the polymerization with the radically polymerizable monomer following this treatment.

The treatment temperature is preferably from -20 to 200°C, more preferably from 50 to 90°C.
The treatment time is preferably 0.1 to 100 hours, more preferably 1 to 5 hours.

Following the above treatment, the polymerization conditions for polymerizing at least one radically polymerizable monomer are as follows:
The polymerization is preferably carried out using a radical polymerization initiator, and examples of the radical polymerization initiator include the radical initiators described above.
The radical polymerization initiator is used in an amount of preferably 0.1 to 10 parts by mass, more preferably 0.4 to 1 part by mass, based on 100 parts by mass of the radical polymerizable monomer.
The polymerization temperature is preferably from 5 to 200°C, more preferably from 50 to 130°C.
The polymerization time is preferably 0.1 to 100 hours, more preferably 1 to 20 hours.

The above polymerization method can produce a polymer with a number average molecular weight Mn of 500 to 1,000,000 and a ratio of weight average molecular weight Mw to number average molecular weight Mn (Mw/Mn) of 1.0 to 5.0.

The method of the present invention in which a disulfide compound is previously treated with a radical initiator and then a radically polymerizable monomer is added to the treated product to carry out radical polymerization can set the ratio [Mn/M(th)] of the number average molecular weight Mn to the design molecular weight M(th) of a polymer obtained by a conventional method in which a disulfide compound, a radical initiator, and a radically polymerizable monomer are added all at once to polymerize the polymer to be less than 1.7, or even 1.5 or less, and particularly 0.7 to 1.3.
This means that it is possible to obtain a polymer of the desired molecular weight.

The reason why it is possible to obtain a polymer with the desired molecular weight is believed to be that when a disulfide compound is treated in advance with a radical initiator as shown in the following general formula (2), the radical (I.) generated from the radical initiator does not contain a radical polymerizable monomer and reacts only with the disulfide compound to generate two molecules of a compound that acts as a RAFT agent, and then the two molecules of the RAFT agent react with the radical polymerizable monomer (M) to obtain a polymer with the desired designed molecular weight.

In contrast, when a disulfide compound, a radical initiator, and a radical polymerizable monomer are added all at once and polymerized, as shown in the following general formula (3), the growing end radical (Pn.) formed by the reaction of the radical (I.) generated from the radical initiator with the radical polymerizable monomer (M) reacts with the disulfide compound, and the resulting compound (a) acts as a RAFT agent, but the resulting thiocarbonylthio radical (b) does not act as a RAFT agent even when it reacts with the radical polymerizable monomer. As a result, one molecule of a compound that acts as a RAFT agent is generated from one molecule of the disulfide compound, and it is thought that a polymer with a molecular weight twice the designed molecular weight is produced.

The present invention will be described in detail below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to these synthesis examples, examples, and comparative examples. The following devices were used to measure the physical properties in each synthesis example, example, and comparative example.

[Molecular Weight Measurement]
Using a gel permeation chromatograph (LC-20A, manufactured by Shimadzu Corporation), the number average molecular weight (Mn) and weight average molecular weight (Mw) were measured in terms of polystyrene under the following conditions. The molecular weight distribution (Mw/Mn) was calculated from the obtained values.
Measurement conditions Column: Tosoh Corporation TSKgel SuperMultiporeHZ-M x 1 Column temperature: 40°C
Eluent: Tetrahydrofuran Detector: RI

[Liquid Chromatography (LC) Measurement]
The measurement was carried out using a liquid chromatography apparatus (GL-7480, manufactured by GL Sciences) under the following conditions.
Measurement conditions Column: Inertsil ODS-2
Column temperature: 40°C
Eluent: tetrahydrofuran/acetonitrile 20/80 (v/v) 1 ml/min Detector: UV, 300 nm

[Gas Chromatography (GC) Measurement]
The measurement was carried out using a gas chromatography apparatus (GC-2014, manufactured by Shimadzu Corporation) under the following conditions.
Measurement conditions: Column: HP-1 10 m, inner diameter 0.530 mm, film thickness 2.65 μm
Oven: 80°C 1 min, 10°C/min, 300°C 5 min Injection temperature: 280°C
Detector: Hydrogen flame ionization detector Detector temperature: 300°C

[Synthesis Example 1]
Synthesis of bis(n-dodecylmercapto-thiocarbonyl) disulfide

A reaction solution was prepared by adding 101 g of n-dodecyl mercaptan, 46 g of carbon disulfide, and 200 g of tetrahydrofuran to a 1 L flask equipped with a reflux condenser, a thermometer, and a stirrer. 58 g of 48% potassium hydroxide aqueous solution was added dropwise using a dropping funnel. During the dropwise addition, the mixture was cooled in a water bath so that the internal temperature was below 40°C. After the dropwise addition, the mixture was stirred and reacted for 1 hour. A solution of 64 g of iodine dissolved in 22 g of tetrahydrofuran was added dropwise. This time, the mixture was also cooled in a water bath to adjust the internal temperature to below 40°C. After the dropwise addition, the mixture was reacted for 1 hour, and then 100 g of water and 100 g of toluene were added and the mixture was separated. The upper layer was further washed with 81 g of 2% sodium sulfite water, and then washed twice with 80 g of water. After the separation, the toluene was removed from the upper layer using an evaporator, and 250 g of methylmethanol and 60 g of toluene were added thereto and stirred for 4 hours under cooling at 5°C to precipitate crystals. The precipitated crystals were filtered and dried under reduced pressure at 30°C or less to obtain 127 g of the titled bis(n-dodecylmercapto-thiocarbonyl) disulfide (yield 91%). The purity determined by liquid chromatography analysis was 97%.

[Synthesis Example 2] Synthesis of bis(thiobenzoyl)disulfide

4.9 g of magnesium was placed in a 1 L flask equipped with a reflux condenser, a thermometer, a nitrogen-filled tube, and a stirrer, and a mixture of 31 g of phenyl bromide and 140 g of tetrahydrofuran was dripped into the flask using a dropping funnel under a nitrogen atmosphere. At this time, the internal temperature was adjusted to 40-50°C using a water bath or air cooling. After the dripping was completed, the mixture was stirred and reacted for 2 hours. A mixture of 15 g of carbon disulfide and 10 g of tetrahydrofuran was dripped into the flask. At this time, the mixture was cooled in a water bath and the internal temperature was adjusted to 40°C or less. After stirring and reacting for 1 hour, a solution of 25 g of iodine dissolved in 35 g of tetrahydrofuran was dripped into the flask. After stirring and reacting for 1 hour, 120 g of water and 115 g of toluene were added and the mixture was separated. The upper layer was washed with 120 g of water, washed twice with 100 g of 5% sodium sulfite, and washed twice with 100 g of water. Toluene was removed from the upper layer using an evaporator, 47 g of ethyl acetate was added, and the mixture was cooled to 5°C to precipitate crystals. The precipitated crystals were filtered and dried under reduced pressure at 30°C to obtain 21 g of the title bis(thiobenzoyl)disulfide (yield 69%). The purity determined by liquid chromatography analysis was 85%.

[Example 1]
A 200 ml flask equipped with a reflux condenser, a thermometer, a nitrogen inlet tube and a stirrer was replaced with nitrogen, and 4.3 parts by mass of bis(n-dodecylmercapto-thiocarbonyl) disulfide, 50 parts by mass of toluene and 1.5 parts by mass of azobisisobutyronitrile were placed in the flask as a disulfide compound, and reacted at 90° C. for 2 hours. Then, 100 parts by mass of butyl acrylate as a polymerization component, 0.4 parts by mass of azobisisobutyronitrile as a radical initiator and 50 parts by mass of toluene were added to the reaction liquid to obtain a composition for radical polymerization. Next, the flask containing the composition for polymerization was heated at 75° C. for 2 hours using an oil bath while stirring under a nitrogen stream, and radical polymerization was performed. After the polymerization reaction was completed, the mixture was returned to room temperature and analyzed. The conversion of butyl acrylate determined by gas chromatography (GC) was 94%, and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) was 7,700 and the polydispersity (Mw/Mn) was 1.08.

[Example 2]
As in Example 1, a composition consisting of 5.6 parts by mass of bis(n-dodecylmercapto-thiocarbonyl) disulfide, 50 parts by mass of toluene, and 2 parts by mass of azobisisobutyronitrile was reacted at 90°C for 2 hours, and then 100 parts by mass of methyl methacrylate, 0.5 parts by mass of azobisisobutyronitrile, and 50 parts by mass of toluene were added to the reaction liquid to prepare a composition for radical polymerization. The composition was heated at 75°C for 6 hours to carry out radical polymerization. After the polymerization reaction was completed, the mixture was returned to room temperature and analyzed. The conversion rate of methyl methacrylate determined by GC was 84%, Mn determined by GPC was 5,600, and Mw/Mn was 1.18.

[Example 3]
As in Example 1, 3.1 parts by mass of bis(thiobenzoyl)disulfide, 50 parts by mass of toluene, and 2 parts by mass of azobisisobutyronitrile were reacted at 90°C for 2 hours, and then 100 parts by mass of methyl methacrylate, 0.5 parts by mass of azobisisobutyronitrile, and 50 parts by mass of toluene were added to the reaction solution to obtain a composition for radical polymerization. The composition was heated at 75°C for 9 hours to carry out radical polymerization. After the polymerization reaction was completed, the mixture was returned to room temperature and analyzed. The conversion rate of methyl methacrylate determined by GC was 85%, Mn determined by GPC was 5,100, and Mw/Mn was 1.14.

[Example 4]
As in Example 1, 2.4 parts by mass of bis(thiobenzoyl) disulfide, 50 parts by mass of toluene, and 1.5 parts by mass of azobisisobutyronitrile were reacted at 90°C for 2 hours, and then 100 parts by mass of butyl acrylate, 0.4 parts by mass of azobisisobutyronitrile, and 50 parts by mass of toluene were added to the reaction solution to obtain a composition for radical polymerization. The composition was heated at 75°C for 20 hours to carry out radical polymerization. After the polymerization reaction was completed, the mixture was returned to room temperature and analyzed. The conversion rate of butyl acrylate determined by GC was 88%, and the Mn determined by GPC was 6,700, and the Mw/Mn was 1.15.

[Comparative Example 1]
A 200 ml flask equipped with a reflux condenser, a thermometer, a nitrogen inlet tube and a stirrer was replaced with nitrogen, and 4.3 parts by mass of bis(n-dodecylmercapto-thiocarbonyl) disulfide as a disulfide compound, 100 parts by mass of toluene as a polymerization solvent, 100 parts by mass of butyl acrylate as a polymerization component and 0.4 parts by mass of azobisisobutyronitrile as a radical initiator were placed in the flask to obtain a composition for radical polymerization. Next, under a nitrogen stream, the flask containing the composition for polymerization was heated at 75° C. for 4 hours using an oil bath while stirring, and radical polymerization was performed. After the polymerization reaction was completed, the mixture was returned to room temperature and analyzed. The conversion rate of butyl acrylate determined by GC was 94%, Mn determined by GPC was 17,200, and Mw/Mn was 1.15.

[Comparative Example 2]
As in Comparative Example 1, a composition for radical polymerization consisting of 5.5 parts by mass of bis(n-dodecylmercapto-thiocarbonyl) disulfide, 100 parts by mass of toluene, 100 parts by mass of methyl methacrylate, and 0.5 parts by mass of azobisisobutyronitrile was heated at 75°C for 6 hours to carry out radical polymerization. After the polymerization reaction was completed, the mixture was returned to room temperature and analyzed. The conversion rate of methyl methacrylate determined by GC was 90%, Mn determined by GPC was 9,500, and Mw/Mn was 1.11.

[Comparative Example 3]
As in Comparative Example 1, a composition for radical polymerization consisting of 3.1 parts by mass of bis(thiobenzoyl)disulfide, 100 parts by mass of toluene, 100 parts by mass of methyl methacrylate, and 1.3 parts by mass of azobisisobutyronitrile was heated at 75°C for 9 hours to carry out radical polymerization. After the polymerization reaction was completed, the mixture was returned to room temperature and analyzed. The conversion rate of methyl methacrylate determined by GC was 83%, and the Mn determined by GPC was 7,600, with the Mw/Mn being 1.30.

[Comparative Example 4]
As in Comparative Example 1, a composition for radical polymerization consisting of 2.4 parts by mass of bis(thiobenzoyl)disulfide, 100 parts by mass of toluene, 100 parts by mass of butyl acrylate, and 1.6 parts by mass of azobisisobutyronitrile was heated at 75°C for 20 hours to carry out radical polymerization. After the polymerization reaction was completed, the mixture was returned to room temperature and analyzed. The conversion rate of butyl acrylate determined by GC was 90%, and the Mn determined by GPC was 11,500, and the Mw/Mn was 1.23.

※逐次とはジスルフィド化合物とラジカル開始剤とをあらかじめ反応させ、続いてラジカル重合性単量体を加え重合することをいう。一括とはジスルフィド化合物、ラジカル開始剤、ラジカル重合性単量体を一括で重合することをいう。
＊設計分子量Ｍ（ｔｈ）とは［（ラジカル重合性単量体とジスルフィド化合物との仕込モル比）×（ラジカル重合性単量体の分子量）×０．５×（モノマー転化率）］＋（実効ＲＡＦＴ剤の分子量）より計算される値である。
§Ｍｎ／Ｍ（ｔｈ）とはＧＰＣ測定より求められた数平均分子量Ｍｎと設計分子量Ｍ（ｔｈ）との比である。 The blending formulations of the polymer compositions and the polymerization results of the above Examples and Comparative Examples are summarized in Table 1 below.

* "Sequential" refers to reacting a disulfide compound with a radical initiator in advance, and then adding a radical polymerizable monomer to polymerize. "All at once" refers to polymerizing a disulfide compound, a radical initiator, and a radical polymerizable monomer all at once.
*The designed molecular weight M(th) is a value calculated from [(charge molar ratio of radical polymerizable monomer to disulfide compound) × (molecular weight of radical polymerizable monomer) × 0.5 × (monomer conversion rate)] + (molecular weight of effective RAFT agent).
Mn/M(th) is the ratio of the number average molecular weight Mn determined by GPC measurement to the designed molecular weight M(th).

The results in Table 1 show that in Examples 1 to 4, in which the disulfide compound, radical initiator, and monomer were reacted successively, the number average molecular weight Mn and the designed molecular weight M(th) were almost the same, and the ratio [Mn/M(th)] was 1.1 to 1.2. In contrast, in Comparative Examples 1 to 4, in which the disulfide compound, radical initiator, and monomer were reacted all at once, the Mn/M(th) was 1.7 to 2.7, and a polymer with a molecular weight 2 to 3 times higher than the desired molecular weight was obtained. This shows that in the polymerization method of the comparative examples, in which the disulfide compound is charged all at once, half of the disulfide compound does not function as a RAFT agent.

The method for producing a polymer of the present invention can be widely applied in the field of free radical polymerization of radically polymerizable monomers such as methacrylates, acrylates, and styrenes. For example, it can be suitably used in the field of adhesives such as adhesives for protective sheets, or as photoresist polymers and sealants. Furthermore, block, star, and branched polymers can be used as thermoplastic elastomers, pigment dispersants for paints, rheology modifiers, etc.

Claims (2)

Relative to 100 parts by mass of a radical polymerizable monomer, a compound represented by the following general formula (1):
[In the formula, R ₁ and R ₂ each independently represent a substituted or unsubstituted aromatic hydrocarbon group, or a group represented by the formula: -S-X-A (wherein X represents a substituted or unsubstituted linear or branched alkylene group having 1 to 20 carbon atoms in which an oxygen atom may be present between the carbon bonds of the alkylene group, if possible, or a substituted or unsubstituted cyclic alkylene group having 3 to 12 carbon atoms, and A represents a hydrogen atom, an alkylamino group, an ester group, a vinyl group, or a substituted or unsubstituted aromatic hydrocarbon group)]
and 0.1 to 50 parts by mass of a disulfide compound represented by the formula (I) and 0.1 to 50 parts by mass of a radical initiator are reacted in advance in 1 to 200 parts by mass of a solvent under conditions of a temperature of −20 to 200° C. and a treatment time of 0.1 to 100 hours , and then at least one radically polymerizable monomer is added to the reaction liquid and radically polymerized under conditions of a polymerization temperature of 5 to 200° C. and a polymerization time of 0.1 to 100 hours (excluding the purification of the RAFT agent from the reaction liquid),
A method for producing a polymer, which obtains a polymer having a number average molecular weight Mn of 500 to 1,000,000, a ratio of weight average molecular weight Mw to number average molecular weight Mn (Mw/Mn) of 1.0 to 5.0, and a ratio of number average molecular weight Mn to design molecular weight M(th) (Mn/M(th)) of 0.7 to 1.3 . 2. The method for producing a polymer according to claim 1 , wherein a random copolymer or a block copolymer is obtained by using two or more kinds of radically polymerizable monomers.