Polymer, resin composition for coating, and film

Abstract

To provide a polymer having a low viscosity even if having a high molecular weight, a resin composition for coating containing the polymer, and a film using the resin composition for coating.SOLUTION: A polymer having a structural unit derived from a styrenic monomer (A), a structural unit derived from a methacrylic monomer (B), and a structure derived from a chain transfer agent (C) represented by the following general formula (1): Wherein R ' is hydrogen, halogen, - OC (= O) R ", - C (= O) NH2, - CN, - C (= O) OR ", or aryl, and Y is - SR ", halogen, - SO2R ", - P (= O) (OR ") 2, - SnR " 3, - SiR " 3, or - C (= O) OR ". Each R " independently represents an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group. ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polymer, a resin composition for coating, and a film. [Background technology]

[0002] Polymers obtained by copolymerizing styrene-based monomers and methacrylic monomers are widely used in a variety of applications, including moldings and coatings. Polymers are required to have various properties such as elastic modulus, mechanical strength, and durability, and physical properties such as molecular weight must be controlled to obtain properties suitable for the application. When a general polymer is used as a molded body or a coating film, the polymer is often dissolved by heat or in a solvent to reduce viscosity. However, since the viscosity of a polymer is proportional to the molecular weight, increasing the molecular weight depending on the application tends to increase the viscosity. Therefore, when a polymer with a high molecular weight is used, it may be necessary to dissolve the polymer at a higher temperature or use a larger amount of solvent. Polymers are classified into linear and hyperbranched polymers, and hyperbranched polymers have lower viscosity than linear polymers with similar molecular weights. Therefore, hyperbranched polymers can be melt-molded at low temperatures and do not require or require small amounts of solvents, which is expected to be effective in saving energy and reducing harmful volatile organic compounds (VOCs).

[0003] Known methods for synthesizing such hyperbranched polymers include, for example, a method using catalytic chain transfer with cobalt (Patent Document 1) and a method using an addition-fragmentation chain transfer (AFCT) agent (Non-Patent Document 1). Although the polymers obtained by the production methods described in Patent Document 1 and Non-Patent Document 1 have been suggested to have branched structures, the synthesis of high molecular weight polymers has not been achieved. Patent Document 2 describes a production method in which a polyacrylate having a high molecular weight and a branched structure can be obtained by appropriately designing the molecular structure of the AFCT agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2000-506189 [Patent Document 2] Japanese Patent Publication No. 2022-147513 [Non-patent literature]

[0005] [Non-Patent Document 1] Seiya Kobatake, Bunichiro Yamada, "Radical polymerization of a trimer of methyl acrylate as polymerizable α-substituted acrylate," Macromolecular Chemistry and Physics, September 1997, Vol. 198, No. 9, pp. 2825-2837 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the viscosity of a polymer is proportional to the molecular weight, and therefore, as the molecular weight increases, the viscosity increases, and the moldability of the polymer and the coatability when using the polymer as a coating agent tend to decrease. An object of the present invention is to provide a polymer that has a high molecular weight but a low viscosity, a coating resin composition containing the polymer, and a film using the coating resin composition. [Means for solving the problem]

[0007] The present invention has the following aspects. [1] A polymer having a structural unit derived from a styrene-based monomer (A), a structural unit derived from a methacrylic monomer (B), and a structure derived from a chain transfer agent (C) represented by the following general formula (1):

[0008] [ka]

[0009] In formula (1), R' is a hydrogen atom, a halogen atom, -OC(=O)R", -C(=O)NH2, -CN, -C(=O)OR" or an aryl group; Y is -SR", a halogen atom, -SOR", -P(=O)(OR")2, -SnR"3, -SiR"3 or -C(=O)OR". Each R" is independently an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group.

[0010] [2] The polymer according to [1], wherein the content of the structural units derived from the styrene-based monomer (A) is 10% by mass or more when the total content of the structural units derived from the styrene-based monomer (A) and the structural units derived from the methacrylic monomer (B) is 100% by mass. [3] The polymer according to [1] or [2] above, wherein the weight-average molecular weight of the polymer is 20,000 or more. [4] The polymer according to any one of [1] to [3] above, wherein the polymer has a branched structure. [5] A resin composition for coating, comprising the polymer according to any one of [1] to [4] above. [6] The coating resin composition according to [5] above, further comprising a solvent. [7] A film using the coating resin composition according to [5] or [6]. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a polymer that has a high molecular weight but a low viscosity, a coating resin composition containing the polymer, and a film using the coating resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to these embodiments. The present invention can be implemented in various forms without departing from the spirit of the present invention. In this specification and claims, a numerical range expressed as "to" means a numerical range that includes the numbers before and after "to" as the lower and upper limits. For example, A to B is equivalent to A or more and B or less. The numerical ranges of the contents, various physical property values, and property values ​​disclosed in this specification can be arbitrarily combined with the lower and upper limits to form new numerical ranges.

[0013] In addition, in the present invention and this specification, the following terms have the following meanings. "(Meth)acrylonitrile" is a general term for "acrylonitrile" and "methacrylonitrile." "(Meth)acrylamide" is a general term for "acrylamide" and "methacrylamide." "(Meth)acrylate" is a general term for "acrylate" and "methacrylate." A "vinyl monomer" is a compound that has a polymerizable double bond. The term "structural unit" refers to a unit that constitutes a polymer derived from a monomer, i.e., a structural unit formed by polymerization of a monomer, or a structural unit in which a portion of the structural unit has been converted into a different structure by modifying a polymer.

[0014] [Polymer] The polymer according to this embodiment (hereinafter also referred to as "polymer (P)") has a structural unit derived from a styrene-based monomer (A), a structural unit derived from a methacrylic monomer (B), and a structure derived from a chain transfer agent (C) shown below. In addition to the chain transfer agent (C), the polymer (P) may optionally contain a chain transfer agent other than the chain transfer agent (C) (hereinafter also referred to as "another chain transfer agent (D)") within a range that does not impair the effects of the present invention. That is, the polymer (P) may further have a structure derived from the other chain transfer agent (D) in addition to the structure derived from the chain transfer agent (C). Furthermore, the polymer (P) may further contain, if necessary, structural units derived from monomers other than the styrene-based monomer (A), the methacrylic monomer (B), the chain transfer agent (C), and the other chain transfer agent (D) (hereinafter also referred to as "other monomers (E)"), as long as the effects of the present invention are not impaired.

[0015] <Styrene-based monomer (A)> Examples of the styrene monomer (A) include α-methylstyrene, vinyltoluene, pt-butoxystyrene, p-acetoxystyrene, p-(1-ethoxyethoxy)styrene, 2-vinylnaphthalene, 3-vinylnaphthalene, 2-t-butoxy-6-vinylnaphthalene, p-chlorostyrene, and styrene, etc. Among these, styrene is preferred in terms of easy availability of the monomer. These styrene-based monomers (A) can be used alone or in combination of two or more.

[0016] <Methacrylic monomer (B)> Examples of the methacrylic acid ester (B) include alkyl methacrylates having an alkyl group having 1 to 30 carbon atoms, hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, glycerol methacrylate, methacrylic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, 2-methacryloyloxypropyl hexahydrophthalic acid, 2-methacryloyloxyethyl phthalic acid, 2-methacryloyloxypropyl phthalic acid, 2-methacryloyloxyethyl maleic acid, and 2-methacryloyloxypropyl maleic acid. Examples include leic acid, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxypropyl succinic acid, glycidyl methacrylate, 3,4-epoxybutyl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, ethoxyethoxyethyl methacrylate, polyethylene glycol methacrylate and its alkyl ethers, benzyl methacrylate, phenyl methacrylate, 3-(triethoxysilyl)propyl methacrylate, and 2-(dimethylamino)ethyl methacrylate and its quaternary alkylammonium salts. Among these, methyl methacrylate, butyl methacrylate, and methacrylic acid are preferred in terms of easy availability of the monomers. These methacrylic monomers (B) can be used singly or in combination of two or more.

[0017] <Chain transfer agent (C)> The chain transfer agent (C) is a compound represented by the following general formula (1).

[0018] [ka]

[0019] In formula (1), R' is a hydrogen atom, a halogen atom, -OC(=O)R", -C(=O)NH2, -CN, -C(=O)OR" or an aryl group; Y is -SR", a halogen atom, -SOR", -P(=O)(OR")2, -SnR"3, -SiR"3 or -C(=O)OR". Each R" is independently an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group.

[0020] Examples of the halogen atom in R' include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a chlorine atom or a bromine atom is preferred. When R' is a halogen atom, the compound exhibits an appropriate chain transfer constant in the step (i) described below.

[0021] The aryl group for R' includes, for example, an aryl group having a carbon number of 6 to 18. Specific examples of the aryl group having a carbon number of 6 to 18 include a phenyl group, a benzyl group, and a naphthyl group. The aryl group may have a substituent. Examples of the substituent include an alkyl group, an aryl group, a carboxy group, an alkoxycarbonyl group, a carbamoyl group, a cyano group, a hydroxy group, an amino group, an amide group, a halogen atom, an allyl group, an epoxy group, an alkoxy group, and a group exhibiting hydrophilicity or ionicity. Examples of the hydrophilic or ionic group include an alkali salt of a carboxy group, an alkali salt of a sulfoxy group, a poly(alkylene oxide) group such as a polyethylene oxide group or a polypropylene oxide group, and a cationic substituent such as a quaternary ammonium base.

[0022] Examples of the halogen atom for Y include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a chlorine atom or a bromine atom is preferred. When Y is a halogen atom, the compound exhibits an appropriate chain transfer constant in the step (i) described below.

[0023] Examples of the alkyl group for R" include linear or branched alkyl groups having 1 to 20 carbon atoms. Specific examples of the linear or branched alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, an i-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an icosyl group.

[0024] Examples of the cycloalkyl group for R" include a cycloalkyl group having 3 to 20 carbon atoms. Specific examples of the cycloalkyl group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and an adamantyl group.

[0025] The aryl group in R" includes, for example, an aryl group having 6 to 18 carbon atoms. Specific examples of the aryl group having 6 to 18 carbon atoms include a phenyl group, a benzyl group, and a naphthyl group.

[0026] Examples of the heterocyclic group for R" include heterocyclic groups having 5 to 18 carbon atoms and containing an oxygen atom, a nitrogen atom, or a sulfur atom as a heteroatom. Specific examples of the heterocyclic group include a γ-lactone group, an ε-caprolactone group, and a morpholine group.

[0027] The alkyl group, cycloalkyl group, aryl group and heterocyclic group in R″ may have a substituent. Examples of the substituent include an alkyl group, an aryl group, a carboxy group, an alkoxycarbonyl group, a carbamoyl group, a cyano group, a hydroxy group, an amino group, an amide group, a halogen atom, an allyl group, an epoxy group, an alkoxy group, and a group exhibiting hydrophilicity or ionicity. Examples of the hydrophilic or ionic group include an alkali salt of a carboxy group, an alkali salt of a sulfoxy group, a poly(alkylene oxide) group such as a polyethylene oxide group or a polypropylene oxide group, and a cationic substituent such as a quaternary ammonium base.

[0028] R" is preferably an alkyl group or a cycloalkyl group, more preferably an alkyl group, further preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and particularly preferably a linear alkyl group having 1 to 6 carbon atoms.

[0029] Examples of the chain transfer agent (C) include 2-(halomethyl)acrylic esters in which R″ in R′ is a linear alkyl group having 1 to 6 carbon atoms, such as methyl 2-(bromomethyl)acrylate, ethyl 2-(bromomethyl)acrylate, and propyl 2-(bromomethyl)acrylate; and 2-(arylsulfonylmethyl)acrylic esters in which R″ in R′ is a linear alkyl group having 1 to 6 carbon atoms, such as methyl 2-(phenylsulfonylmethyl)acrylate, ethyl 2-(phenylsulfonylmethyl)acrylate, and propyl 2-(phenylsulfonylmethyl)acrylate. Among these, 2-(halomethyl)acrylates and 2-(arylsulfonylmethyl)acrylates, in which R" in R' is a linear alkyl group having 1 to 6 carbon atoms, are preferred; 2-(bromomethyl)acrylates and 2-(phenylsulfonylmethyl)acrylates, in which R" in R' is a linear alkyl group having 1 to 6 carbon atoms, are more preferred; 2-(bromomethyl)methyl acrylate, ethyl 2-(bromomethyl)acrylate, propyl 2-(bromomethyl)acrylate, methyl 2-(phenylsulfonylmethyl)acrylate, propyl 2-(phenylsulfonylmethyl)acrylate, ethyl 2-(phenylsulfonylmethyl)acrylate, and methyl 2-(phenylsulfonylmethyl)acrylate are even more preferred; and 2-(bromomethyl)ethyl acrylate and methyl 2-(phenylsulfonylmethyl)acrylate are particularly preferred. These chain transfer agents (C) can be used alone or in combination of two or more.

[0030] <Other chain transfer agents (D)> As the other chain transfer agent (D), a chain transfer agent in which a growing terminal radical of the polymer abstracts a hydrogen atom in the chain transfer agent molecule to generate a radical is preferred, and examples thereof include -OH, -SH, -C(=O)OH, -NH2, -NHR 1d A chain transfer agent having at least one group selected from the group consisting of —SO3H is more preferred. 1d is an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group.

[0031] Other chain transfer agents (D) include mercapto group-containing chain transfer agents such as n-dodecyl mercaptan and t-dodecyl mercaptan; and secondary hydroxyl group-containing chain transfer agents such as isopropyl alcohol. These other chain transfer agents (D) can be used alone or in combination of two or more.

[0032] <Other Monomers (E)> The other monomer (E) is not particularly limited as long as it is a monomer other than the styrene-based monomer (A), the methacrylic-based monomer (B), the chain transfer agent (C), and the other chain transfer agent (D), and examples thereof include acrylate-based compounds and vinyl monomers other than acrylate-based compounds (hereinafter also referred to as "other vinyl monomers"). Among these, acrylate-based compounds are preferred. These other monomers (E) can be used singly or in combination of two or more.

[0033] Examples of the acrylate compounds include alkyl acrylates having an alkyl group having 1 to 30 carbon atoms, hydroxyethyl acrylate, hydroxypropyl acrylate, glycidyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, ethoxyethoxyethyl acrylate, polyethylene glycol acrylate and its alkyl ethers, benzyl acrylate, phenyl acrylate, 3-(triethoxysilyl)propyl acrylate, and 2-(dimethylamino)ethyl acrylate and its quaternary alkylammonium salts. As the alkyl acrylate having an alkyl group having 1 to 30 carbon atoms, an alkyl acrylate having a linear or branched alkyl group having 1 to 10 carbon atoms is preferred, an alkyl acrylate having a linear or branched alkyl group having 1 to 10 carbon atoms is more preferred, an alkyl acrylate having a linear alkyl group having 1 to 6 carbon atoms and an alkyl acrylate having a branched alkyl group having 3 to 10 carbon atoms are particularly preferred, and n-butyl acrylate and 2-ethylhexyl acrylate are most preferred. These acrylate compounds can be used alone or in combination of two or more.

[0034] The other vinyl monomers are not particularly limited as long as they are capable of radical polymerization, and examples thereof include vinyl ether monomers such as methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether; fumaric acid, monoalkyl esters and dialkyl esters of fumaric acid; maleic acid, monoalkyl esters and dialkyl esters of maleic acid; itaconic acid, monoalkyl esters and dialkyl esters of itaconic acid; (meth)acrylonitrile, (meth)acrylamide, butadiene, isoprene, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl ketone, vinylpyridine, and vinylcarbazole. These other vinyl monomers can be used alone or in combination of two or more.

[0035] <Content> The content of the structural units derived from the styrene-based monomer (A) in the polymer (P) is preferably 10% by mass or more, more preferably 10 to 80% by mass, even more preferably 15 to 70% by mass, and particularly preferably 20 to 60% by mass, when the total content of the structural units derived from the styrene-based monomer (A) and the structural units derived from the methacrylic monomer (B) is taken as 100% by mass. When the content of the structural units derived from the styrene-based monomer (A) is equal to or greater than the above-mentioned lower limit, properties such as hydrophobicity and low moisture absorption derived from the styrene-based monomer (A) can be sufficiently obtained. When the content of the structural units derived from the styrene-based monomer (A) is equal to or less than the above-mentioned upper limit, sufficient solubility can be ensured.

[0036] The content of the structure derived from the chain transfer agent (C) in the polymer (P) is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.2 to 3 parts by mass, relative to 100 parts by mass of the total of the content of the structural units derived from the styrene-based monomer (A) and the content of the structural units derived from the methacrylic monomer (B). When the content of the structure derived from the chain transfer agent (C) is equal to or greater than the above-mentioned lower limit, the polymer (P) is likely to have an appropriate branched structure. When the content of the structure derived from the chain transfer agent (C) is equal to or less than the above-mentioned upper limit, the properties of the polymer (P), such as elastic modulus, mechanical strength, and durability, can be sufficiently obtained.

[0037] The total content of the structural units derived from the styrene-based monomer (A), the structural units derived from the methacrylic monomer (B), and the structure derived from the chain transfer agent (C) in the polymer (P) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total mass of all structural units constituting the polymer (P).

[0038] The content of the structure derived from the other chain transfer agent (D) in the polymer (P) is preferably 0 to 3 parts by mass, more preferably 0.2 to 2 parts by mass, and even more preferably 0.3 to 1.5 parts by mass, relative to 100 parts by mass of the total of the content of the structural units derived from the styrene-based monomer (A) and the content of the structural units derived from the methacrylic monomer (B).

[0039] The content of the structural units derived from the other monomer (E) in the polymer (P) is preferably 0 to 20 parts by mass, more preferably 0 to 15 parts by mass, and even more preferably 0 to 10 parts by mass, relative to 100 parts by mass of the total of the content of the structural units derived from the styrene-based monomer (A) and the content of the structural units derived from the methacrylic monomer (B).

[0040] <Structure of polymer (P)> The polymer (P) preferably has a structure represented by the following general formula (2).

[0041] [ka]

[0042] The meanings of the symbols in formula (2) are as follows: R is a hydrogen atom, a halogen atom, —OC(═O)R″, —C(═O)NH2, —CN, —C(═O)OR″, or an aryl group. Each R″ is independently an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group. R 1 ~R n are each independently —C(═O)OW or an aryl group. W is each independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group, and may have a substituent. Z is a group derived from a radical polymerization initiator, a group derived from a chain transfer agent (C), or a group derived from another chain transfer agent (D). X 1 ~X n are each independently a hydrogen atom, a methyl group, or a structure represented by the following general formula (3), and X 1 ~X n At least one of the above has a structure represented by the following general formula (3). R n and X n In this equation, n is a natural number between 2 and 10,000.

[0043] [ka]

[0044] The meanings of the symbols in formula (3) are as follows: R is a hydrogen atom, a halogen atom, —OC(═O)R″, —C(═O)NH2, —CN, —C(═O)OR″, or an aryl group. Each R″ is independently an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group. R 1 ~R n are each independently —C(═O)OW or an aryl group. W is each independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group, and may have a substituent. Z is a group derived from a radical polymerization initiator, a group derived from a chain transfer agent (C), or a group derived from another chain transfer agent (D). X 1 ~X n are each independently a hydrogen atom, a methyl group, or a structure represented by the general formula (3). R n and X n In the above formula, n is a natural number between 2 and 10,000. The wavy lines in formula (3) represent the bonding positions to adjacent groups.

[0045] R and R in formula (2) 1 ~R n and R in equation (3) 1 ~R n are independent of each other, and X in formula (2) 1 ~X n and X in equation (3) 1 ~X n are independent of each other.

[0046] R in equation (2) 1 ~R n and R in formula (3) 1 ~R n At least one of them is —C(═O)OW and at least one of them is an aryl group.

[0047] X in equation (2) 1 ~X nAt least one of these has a structure represented by general formula (3), and therefore the polymer (P) having a structure represented by general formula (2) has a branched structure.

[0048] The polymer (P) having the structure represented by the general formula (2) and the general formula (3) is 1 In H-NMR measurement, it has peaks with chemical shift values ​​of 5.5 to 5.6 ppm and 6.1 to 6.2 ppm, and 13 This can be confirmed by the presence of a peak with a chemical shift value of 38 to 41 ppm in C-NMR measurement. where: 1 The peaks having chemical shift values ​​of 5.5 to 5.6 ppm and 6.1 to 6.2 ppm in H-NMR measurement indicate the presence of a terminal double bond in the polymer (P) represented by general formula (2). 13 A peak having a chemical shift value of 38 to 41 ppm in C-NMR measurement means that the polymer (P) has a branched structure represented by general formula (3).

[0049] The polymer (P) preferably has a terminal double bond introduced therein, as shown in general formula (2). This terminal double bond is polymerizable and is useful because it allows for the easy synthesis of a graft polymer by copolymerizing it with a vinyl monomer.

[0050] The polymer (P) preferably has structural units derived from a methacrylic monomer and a styrene monomer, and a structure derived from the chain transfer agent (C), as shown in general formula (2) and general formula (3).

[0051] In the polymer (P), in the general formula (2) and the general formula (3), R 1 ~R n When the ratio of the number of moles of aryl groups to the total number of moles of —C(═O)OW and aryl groups contained in the formula (I) is x, x is preferably 10 mol % or more, more preferably 20 mol % or more, and even more preferably 30 mol % or more. When x is 10 mol % or more, the polymer (P) has a high degree of branching. Note that x is a value determined from the charge ratio of the styrene-based monomer (A) and the methacrylic monomer (B) that are raw materials.

[0052] <Physical properties of polymer (P)> The weight-average molecular weight of the polymer (P) is not particularly limited, but is preferably at least 20,000, more preferably at least 30,000, and is preferably at most 1,000,000, more preferably at most 500,000. By using such a polymer (P) as a raw material, molded articles and films excellent in elastic modulus and mechanical strength can be obtained. The weight average molecular weight of the polymer (P) is a value calculated by converting the value measured by gel permeation chromatography (GPC) into that of standard polymethyl methacrylate (PMMA).

[0053] The viscosity of a solution obtained by dissolving polymer (P) in propylene glycol monomethyl ether (PGME) to a concentration of 33.3 mass % (hereinafter also referred to as "solution viscosity of polymer (P)") is preferably 100 to 30,000 mPa·s, more preferably 150 to 10,000 mPa·s, and even more preferably 200 to 2,500 mPa·s. When the solution viscosity of the polymer (P) is equal to or less than the upper limit, low viscosity can be achieved, resulting in excellent handleability.When the solution viscosity of the polymer (P) is equal to or more than the lower limit, process suitability for producing a coating film and the like is improved. The solution viscosity of the polymer (P) is the viscosity at 25° C., and can be measured by the method described in the examples.

[0054] <Method for producing polymer (P)> The method for producing the polymer (P) includes, for example, a method including the following step (i): Step (i): A step of subjecting a polymerizable composition containing a styrene-based monomer (A), a methacrylic monomer (B), a chain transfer agent (C) represented by the general formula (1), and a polymerization initiator (F) to polymerization. The polymerizable composition may contain, as necessary, any one or two or more of other chain transfer agents (D), other monomers (E), organic solvents and other additives.

[0055] The polymerization initiator (F) is not particularly limited, and any known compound can be used, but a radical polymerization initiator is preferred. Examples of the radical polymerization initiator include azo-based radical polymerization initiators and peroxide-based radical polymerization initiators.

[0056] Specific examples of the azo-based radical polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile). Specific examples of the peroxide-based radical polymerization initiator include 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-hexyl peroxypivalate, 2,4-dichlorobenzoyl peroxide, t-butyl peroxypivalate, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, t-butylperoxy-2-ethylhexanoate, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, and di-t-butyl peroxide. These radical polymerization initiators can be used alone or in combination of two or more.

[0057] The organic solvent is not particularly limited, but examples thereof include alcohol-based solvents such as methanol and ethanol; aromatic hydrocarbon-based solvents such as toluene, ethylbenzene, xylene, and anisole; ketone-based solvents such as acetone, methyl isobutyl ketone, and methyl ethyl ketone; and ester-based solvents such as butyl acetate and ethyl acetate. These organic solvents can be used alone or in combination of two or more.

[0058] Examples of other additives include pigments, ultraviolet absorbers, release agents, antifoaming agents, plasticizers, viscosity modifiers, etc. Known compounds can be used as these additives. These other additives may be used alone or in combination of two or more.

[0059] The content of the styrene-based monomer (A) in the polymerizable composition is preferably 10% by mass or more, more preferably 10 to 80% by mass, even more preferably 15 to 70% by mass, and particularly preferably 20 to 60% by mass, when the total of the styrene-based monomer (A) and the methacrylic monomer (B) is taken as 100% by mass. When the content of the styrene-based monomer (A) is equal to or greater than the above-mentioned lower limit, a polymer (P) having sufficient properties derived from the styrene-based monomer (A), such as hydrophobicity and low moisture absorption, can be obtained. When the content of the styrene-based monomer (A) is equal to or less than the above-mentioned upper limit, a polymer (P) having sufficient solubility can be obtained.

[0060] The content of the chain transfer agent (C) in the polymerizable composition is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.2 to 3 parts by mass, relative to 100 parts by mass of the total content of the styrene-based monomer (A) and the methacrylic monomer (B). When the content of the chain transfer agent (C) is equal to or greater than the above-mentioned lower limit, a branched structure can be appropriately introduced into the resulting polymer (P). When the content of the chain transfer agent (C) is equal to or less than the above-mentioned upper limit, the properties of the polymer (P), such as elastic modulus, mechanical strength, and durability, can be sufficiently obtained.

[0061] The content of the polymerization initiator (F) in the polymerizable composition is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and even more preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of the total content of the styrene-based monomer (A) and the methacrylic monomer (B). When the content of the polymerization initiator (F) is within the above range, an appropriate polymerization rate can be obtained in step (i).

[0062] The content of the organic solvent in the polymerizable composition is preferably 0 to 300 parts by mass, more preferably 0 to 200 parts by mass, and even more preferably 0 to 150 parts by mass, relative to 100 parts by mass of the total content of the styrene-based monomer (A) and the methacrylic monomer (B). When the content of the organic solvent is within the above range, an appropriate polymerization rate can be obtained in step (i), and the viscosity of the solution after the production of the polymer (P), i.e., the reaction solution containing the polymer (P), is reduced, resulting in excellent handleability.

[0063] The content of the other chain transfer agent (D) in the polymerizable composition is preferably 0 to 3 parts by mass, more preferably 0.2 to 2 parts by mass, and even more preferably 0.3 to 1.5 parts by mass, relative to 100 parts by mass of the total of the content of the styrene-based monomer (A) and the content of the methacrylic monomer (B).

[0064] The content of the other monomer (E) in the polymerizable composition is preferably 0 to 20 parts by mass, more preferably 0 to 15 parts by mass, and even more preferably 0 to 10 parts by mass, relative to 100 parts by mass of the total of the content of the styrene-based monomer (A) and the content of the methacrylic monomer (B).

[0065] By polymerizing the polymerizable composition described above in the step (i), a graft polymer, which is a polymer (P) having a branched chain or a polymer (P) having a graft chain, can be easily produced. In this specification, a "graft polymer" refers to a polymer compound having one or more types of blocks connected as side chain polymer structures to a main chain polymer structure. In a polymer (P) having a branched chain, the structures of the main chain polymer and the side chain polymer may be different or the same. On the other hand, in a graft polymer, the structures of the main chain polymer and the side chain polymer differ in the type (structure) of the monomer unit, or, even if they contain the same monomer unit, differ in composition or sequence distribution.

[0066] Conventional methods for producing graft polymers include, for example, a method in which a macromonomer having a terminal radically polymerizable double bond is produced as a side chain polymer structure, followed by radical polymerization with a monomer that will become a structural unit of the main chain polymer; a method in which a main chain polymer having a reactive site and a macromonomer having a reactive site are produced in advance, followed by reaction thereof; and a method in which, after the main chain polymer is produced, a radical is generated on the main chain polymer using an initiator having hydrogen abstraction ability, and then a monomer that will become a structural unit of the side chain polymer is reacted to produce a side chain polymer structure. Note that "macromonomer" refers to a polymer having a radically polymerizable group or an addition-reactive functional group. All of these methods require two or more polymerization stages. In contrast, according to the method for producing the polymer (P) of this embodiment, the polymer (P) having a branched chain or a graft chain can be produced by only one polymerization step, i.e., only the step (i). Note that the method for producing the polymer (P) of this embodiment may further include a second or subsequent polymerization step.

[0067] The polymerization method for the polymerizable composition is not particularly limited, and any conventionally known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization can be used. Among these, suspension polymerization is preferred. When the polymerizable composition is polymerized by suspension polymerization, water is preferred as the reaction solvent. The polymerization reaction may be carried out in the presence of air, but is preferably carried out in an inert gas atmosphere such as nitrogen or argon from the viewpoint of the efficiency of radical polymerization. Known techniques for carrying out the polymerization in an inert gas atmosphere can be used, and examples of such techniques include a technique of blowing an inert gas into the polymerizable composition and a technique of repeatedly freezing, degassing, and thawing the polymerizable composition.

[0068] The polymerization temperature is not particularly limited, but is preferably 0 to 150°C, more preferably 20 to 120°C, from the viewpoint of the polymerization rate. The polymerization time is not particularly limited, but is preferably 0.5 to 48 hours, more preferably 2 to 24 hours.

[0069] <Action and effect> The polymer (P) according to the present embodiment described above has the structural units derived from the styrene-based monomer (A), the structural units derived from the methacrylic monomer (B), and the structure derived from the chain transfer agent (C) represented by general formula (1), and therefore has a low viscosity even though it has a high molecular weight. For example, even if the weight-average molecular weight of the polymer (P) is 20,000 or more, the solution viscosity of the polymer (P) is likely to be maintained at 30,000 mPa s or less.

[0070] <Application> The polymer (P) may be used alone or as a main component, or may be used as an additive to other resins. When the polymer (P) is used alone or as a main component, it can be used as a melt-moldable molding material to produce various molded articles such as sheets and films, various housings and covers, light guides, etc. In addition, by dissolving it in a solvent and then applying it, it can be used as a paint, adhesive, pressure-sensitive adhesive, film, etc.

[0071] When the polymer (P) is used as an additive for other resins, the other resins that serve as the main component are not particularly limited as long as they are resins other than the polymer (P), and examples thereof include acrylic resins such as polymethyl methacrylate, polyolefins, polyamides, unsaturated polyesters, saturated polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, polystyrenes, ABS resins, AS resins, polyvinyl chloride, polylactic acid, and polyvinylidene fluoride. Examples of the functions that the polymer (P) imparts to other resins include flexibility, toughness, impact resistance, weather resistance, processability, mold releasability, scratch resistance, surface hardness, compatibility, crystal size control, ductility, and the like. Methods for mixing the polymer (P) with other resins include physical mixing, melt mixing, and methods in which the polymer (P) is dissolved or dispersed before polymerization or curing.

[0072] [Coating resin composition] The coating resin composition according to this embodiment (hereinafter also referred to as "coating resin composition (X)") contains the above-mentioned polymer (P). The coating resin composition (X) may be used as a solvent-free type or as a solvent-based type by blending a solvent therein. That is, the coating resin composition (X) may further contain a solvent in addition to the polymer (P). Furthermore, the coating resin composition (X) may further contain, in addition to the polymer (P), components other than the polymer (P) and the solvent (hereinafter also referred to as "optional components"), as necessary, within a range that does not impair the effects of the present invention.

[0073] The content of the polymer (P) in the coating resin composition (X) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, based on the total mass of the coating resin composition (X). The content of the polymer (P) may be 100% by mass, based on the total mass of the coating resin composition (X). That is, the coating resin composition (X) may consist solely of the polymer (P).

[0074] The solvent is not particularly limited, but examples thereof include ether-based solvents such as propylene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbon-based solvents such as toluene and xylene; alcohol-based solvents such as methanol, ethanol, and isopropyl alcohol; and ester-based solvents such as ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate. These solvents can be used alone or in combination of two or more.

[0075] The content of the solvent in the coating resin composition (X) is preferably 10 to 90 mass %, more preferably 15 to 80 mass %, and even more preferably 20 to 75 mass %, based on the total mass of the coating resin composition (X). When the content of the solvent is equal to or greater than the above lower limit, a coating film obtained by applying the coating resin composition (X) to a substrate or the like described below can have a sufficient film thickness. When the content of the solvent is equal to or less than the above upper limit, an increase in the viscosity of the coating resin composition (X) can be suppressed, and the coating resin composition (X) has excellent handleability when applied to a substrate or the like.

[0076] The optional components are not particularly limited, but examples thereof include fillers, crosslinking agents, tackifying resins, antioxidants, light stabilizers, metal deactivators, antioxidants, moisture absorbents, rust inhibitors, hydrolysis inhibitors, photoinitiators, photosensitizers, thermal initiators, adhesion promoters, and reaction catalysts.

[0077] The content of the optional components in the coating resin composition (X) is preferably 5 to 50 mass %, more preferably 10 to 40 mass %, and even more preferably 15 to 30 mass %, based on the total mass of the coating resin composition (X).

[0078] The method for producing the coating resin composition (X) is not particularly limited, and for example, the polymer (P) may be used as it is as the coating resin composition (X). Alternatively, the coating resin composition (X) may be produced by mixing the polymer (P), a solvent, and, if necessary, optional components.

[0079] [film] The film according to this embodiment (hereinafter also referred to as "film (Y)") is a film using the above-mentioned coating resin composition (X). That is, the film (Y) contains the above-mentioned polymer (P).

[0080] The content of polymer (P) in film (Y) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the total mass of film (Y). Alternatively, the content of polymer (P) may be 100% by mass, based on the total mass of film (Y). That is, film (Y) may consist solely of polymer (P).

[0081] The thickness of the film (Y) is not particularly limited and may be determined appropriately depending on the application, but is preferably 0.1 to 100 μm, more preferably 1 to 50 μm, for example.

[0082] The film (Y) can be obtained, for example, by applying the coating resin composition (X) onto a substrate and drying it as necessary. In this specification, a product comprising a substrate and a film (Y) formed on the substrate is also referred to as a "laminate."

[0083] As the substrate, a commonly used material can be used, for example, a film, a molding material other than a film, etc. Examples of the film include resin films, metal film paper, etc. Among these, resin films are preferred from the viewpoint of processability. Examples of resin films include polyester films, poly(meth)acrylate films, polyolefin films, polycarbonate films, polyimide films, triacetyl cellulose films, polystyrene films, polyvinyl chloride films, polyvinyl alcohol films, and nylon films.

[0084] The method for applying the coating resin composition (X) to a substrate is not particularly limited, and any common method can be used, such as spin coating, slit coating, spray coating, gravure coating, bar coating, and roll coating.

[0085] If the substrate is subjected to a release treatment in advance, the film (Y) can be easily peeled off from the substrate, and the film (Y) can be used alone.

[0086] The film (Y) may also be produced by molding (forming) the coating resin composition (X) into a film. Examples of the molding method include melt extrusion methods such as melt casting, T-die method and inflation method; and calendering method.

[0087] The application of the film (Y) of this embodiment is not particularly limited, and it can be used in a wide range of applications, such as building materials, paint replacements, high-brightness reflective materials, optical and electronic materials, etc. More specifically, it can be used in applications such as decorative films, scratch-resistant films, cover films, and dry film resists.

[0088] For example, when the film (Y) is used as a dry film resist, the dry film resist is produced by applying the coating resin composition (X) to a desired film thickness on a transparent resin film such as a polyethylene terephthalate film, drying it as necessary to form the film (Y), and then laminating a protective film such as a polyethylene film on the film (Y). [Example]

[0089] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples as long as it does not deviate from the gist of the present invention, and various modifications are possible as long as they do not deviate from the gist of the present invention.

[0090] [Raw materials] The abbreviations for the raw materials used in the examples and comparative examples are shown below.

[0091] <Styrene-based monomer (A)> St: Styrene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0092] <Methacrylic monomer (B)> MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "Acryester (registered trademark) M") BMA: n-butyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "Acryester (registered trademark) B") MAA: Methacrylic acid (Mitsubishi Chemical Corporation)

[0093] <Chain transfer agent (C)> ASME: methyl 2-(phenylsulfonylmethyl)acrylate (produced in Production Example 2 below, a compound in which R' in general formula (1) is -C(=O)OR" (R" is a methyl group) and Y is -SOR" (R" is an aryl group).

[0094] <Other chain transfer agents (D)> tDM: t-dodecyl mercaptan (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0095] <Polymerization initiator (F)> Perocta O: 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate (NOF Corporation)

[0096] [Measurement and evaluation methods] <Measurement of weight average molecular weight of polymer (P)> The weight average molecular weight of the polymer (P) was measured using gel permeation chromatography (GPC) (manufactured by Tosoh Corporation, product name "HLC-8320") as follows. The polymer (P) was dissolved in tetrahydrofuran to a concentration of 0.2% by mass to prepare a tetrahydrofuran solution. 10 μL of the solution was then injected into an apparatus equipped with columns manufactured by Tosoh Corporation (TSKgel SuperHZM-M (inner diameter 4.6 mm, length 15 cm), HZM-M (inner diameter 4.6 mm, length 15 cm), HZ-2000 (inner diameter 4.6 mm, length 15 cm), TSKguardcolumn SuperHZ-L (inner diameter 4.6 mm, length 3.5 cm)). Measurement was performed under the conditions of a flow rate of 0.35 mL / min, an eluent of tetrahydrofuran (stabilizer BHT), and a column temperature of 40°C, and the weight-average molecular weight (Mw) was calculated in terms of standard PMMA.

[0097] <Measurement of Solution Viscosity of Polymer (P)> The polymer (P) was dissolved in propylene glycol monomethyl ether (PGME) to a solids concentration of 33.3% by mass, and after visually confirming that no undissolved polymer (P) remained, a resin composition was obtained that was liquid at room temperature (23°C). The solution viscosity of the resin composition was measured at 25.0°C using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name "TV-25"). The obtained value was taken as the solution viscosity of the polymer (P).

[0098] <Solubility test> The test piece was immersed for 5 minutes in a 3.0% by mass aqueous sodium carbonate solution heated to 60°C. The test piece was then removed from the aqueous sodium carbonate solution and rinsed with ion-exchanged water for 2 minutes. After rinsing, the test piece was visually observed, and the dissolution rate of the film (Y) was evaluated according to the following criteria. A: It was completely dissolved. B: Some of it remained undissolved. C: Not dissolved at all.

[0099] [Production Example 1: Synthesis of Dispersant (1)] A reactor equipped with a stirrer, a cooling tube, and a thermometer was charged with 61.6 parts by mass of a 17% by mass aqueous potassium hydroxide solution, 19.1 parts by mass of MMA, and 19.3 parts by mass of deionized water. The liquid in the reactor was then stirred at room temperature, and after confirming the exothermic peak, the mixture was stirred for 4 hours. The reaction liquid in the reactor was then cooled to room temperature to obtain an aqueous solution of dispersant (1).

[0100] [Production Example 2: Synthesis of ASME] A 2.0 L separable flask was charged with 48.06 g (480.0 mmol) of methyl methacrylate and 252.8 g of methanol, and the mixture was cooled to 0°C. Then, 144.2 g (568.0 mmol) of iodine and 201.8 g (1008 mmol) of sodium benzenesulfinate dihydrate were added little by little, and the mixture was stirred at room temperature for 5 hours. Next, 800.0 mL of dichloromethane was added for dilution, and 160.0 mL of saturated aqueous sodium carbonate solution and 160.0 mL of 5% aqueous sodium hyposulfite solution were added. After separation, 30.00 g of magnesium sulfate was added to the organic layer for drying, and the solvent was then distilled off. Next, 280.0 mL of dichloromethane was added, and 97.14 g (960.0 mmol) of triethylamine was added dropwise over 30 minutes, followed by stirring at room temperature for 2 hours. Next, the solvent was distilled off, and then column chromatography was carried out using 3.000 kg of silica gel to obtain 61.00 g of ASME as a white solid.

[0101] [Example 1] In a polymerization apparatus equipped with a stirrer, a condenser, and a thermometer, 145 parts by mass of deionized water and 0.27 parts by mass of the dispersant (1) produced in Production Example 1 were added and stirred to form a uniform aqueous solution. Next, 40.0 parts by mass of St as the styrene-based monomer (A), 60.0 parts by mass of MMA as the methacrylic monomer (B), 0.50 parts by mass of ASME as the chain transfer agent (C), and 0.4 parts by mass of Perocta O as the polymerization initiator (F) were added to prepare a polymerizable composition. The atmosphere inside the polymerization apparatus was then thoroughly purged with nitrogen, and the polymerizable composition was heated to 87°C and held there for 3 hours, then heated to 95°C and held there for 30 minutes. The reaction solution was then cooled to 40°C to obtain an aqueous suspension of polymer (P). This aqueous suspension was filtered through a filter cloth, and the filtrate was washed with deionized water and dried at 40°C for 16 hours to obtain polymer (P). The weight average molecular weight and solution viscosity of the obtained polymer (P) were measured, and the results are shown in Table 1. Note that blank spaces in Table 1 mean that the component was not blended (amount blended: 0 parts by mass).

[0102] [Examples 2 to 4, Comparative Examples 1 to 4] Polymer (P) was produced in the same manner as in Example 1, except that the amounts of the monomers and chain transfer agent used were changed as shown in Table 1. The weight average molecular weight and solution viscosity of the obtained polymer (P) were measured, and the results are shown in Table 1.

[0103] [Table 1]

[0104] As shown in Table 1, the polymer (P) obtained in Example 1 had a lower solution viscosity than the polymer (P) obtained in Comparative Example 1, which had the same polymer composition and a similar weight-average molecular weight. Similarly, the polymer (P) obtained in Example 2 had a lower solution viscosity than the polymer (P) obtained in Comparative Example 2, the polymer (P) obtained in Example 3 had a lower solution viscosity than the polymer (P) obtained in Comparative Example 3, and the polymer (P) obtained in Example 4 had a lower solution viscosity than the polymer (P) obtained in Comparative Example 4. It is generally known that the solution viscosity of a polymer having the same polymer composition is proportional to the weight-average molecular weight of the polymer, and therefore, as the weight-average molecular weight increases, the solution viscosity also tends to increase. These results indicate that the polymer (P) of the present invention is likely to have a highly branched structure due to the presence of a structure derived from the chain transfer agent (C), and can have a lower viscosity than a polymer with the same composition and a similar weight-average molecular weight. Furthermore, since the polymer (P) of the present invention has a low solution viscosity even when it has a high molecular weight, improvements in moldability and handleability during application can be expected.

[0105] [Example 5, Comparative Example 5] The polymer (P) obtained in Example 4 or Comparative Example 4 was dissolved in PGME in the ratio shown in Table 2, and after visually confirming that no undissolved polymer remained, a resin composition was obtained that was liquid at room temperature (23°C). The obtained resin composition was applied to a copper plate with a thickness of 0.3 mm using an applicator and dried at 90°C for 3 minutes to form a film (Y) with a thickness of 6.25 µm. Next, the copper plate on which the film (Y) was formed was cut into strips with a width of 10 mm and a length of 20 mm to prepare test pieces. The obtained test piece was subjected to a solubility test to evaluate the dissolution rate of the film (Y). The results are shown in Table 2.

[0106] [Table 2]

[0107] As shown in Table 2, in the test piece of Example 5 using the polymer (P) having a branched structure, the film (Y) was completely dissolved after the dissolution test, and the dissolution rate was faster than that of the test piece obtained in Comparative Example 5. If the dissolution rate of the film is fast, when it is used as the main component of a resist film such as a dry film resist, the resolution will be high, and therefore finer resist patterns can be drawn.

Claims

1. A polymer having a structural unit derived from a styrene-based monomer (A), a structural unit derived from a methacrylic monomer (B), and a structure derived from a chain transfer agent (C) represented by the following general formula (1): 【Chemistry 1】 (In formula (1), R' represents a hydrogen atom, a halogen atom, -OC(=O)R", -C(=O)NH ２ , —CN, —C(═O)OR″, or an aryl group, and Y is —SR″, a halogen atom, —SO ２ R”, ​​-P (=O) (OR”) ２ , -SnR" ３ , -SiR" ３ or —C(═O)OR″, where each R″ is independently an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group.

2. 2. The polymer according to claim 1, wherein the content of the structural units derived from the styrene-based monomer (A) is 10% by mass or more when the total content of the structural units derived from the styrene-based monomer (A) and the structural units derived from the methacrylic monomer (B) is 100% by mass.

3. The polymer according to claim 1, wherein the weight average molecular weight of the polymer is 20,000 or more.

4. The polymer of claim 1 , wherein the polymer has a branched structure.

5. A coating resin composition comprising the polymer according to claim 1.

6. The coating resin composition according to claim 5 , further comprising a solvent.

7. A film using the coating resin composition according to claim 5 or 6.

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