WO2022236548A1

WO2022236548A1 - Star polymer, coating material, coating film, and method for producing star polymer

Info

Publication number: WO2022236548A1
Application number: PCT/CN2021/092688
Authority: WO
Inventors: Shizheng HOU; Hisakazu Tanaka; Chao Wang; Juyan HAN
Original assignee: Dic Corporation
Priority date: 2021-05-10
Filing date: 2021-05-10
Publication date: 2022-11-17

Abstract

A star polymer includes a core portion and an arm portion that is a polymer chain attached to the core portion. The arm portion has a functional group at a distal end thereof, the arm portion has a number average molecular weight of 10,000 or more as measured by gel permeation chromatography (GPC (RI)), and the star polymer has a number average molecular weight of 100,000 or more as measured by gel permeation chromatography (GPC (RI)).

Description

STAR POLYMER, COATING MATERIAL, COATING FILM, AND METHOD FOR PRODUCING STAR POLYMER

Technical Field

The present invention relates to a star polymer, a coating material, a coating film, and a method for producing a star polymer.

Background Art

It has been known that in various applications of polymers, in terms of heat resistance and the like, it is preferable to increase the molecular weight of a base polymer. However, in the case where the molecular weight of a polymer is increased with the molecular structure of the polymer remaining a conventional linear structure, the viscosity of the polymer solution increases. As a result, when the polymer is used, there is a problem in that the polymer solution is difficult to apply, for example.

As one object for solving such a problem, the development of a star polymer has been advanced (e.g., PTLs 1 to 2) .

As a method for preparing a star polymer, a method in which arm portions of a star polymer are first prepared using a living polymerization method, and then a copolymerization reaction is performed using a polyvinyl compound or the like, thereby giving a star polymer, is known (Arm First method) . Use of this method allows a star polymer to be obtained in a simple manner, and the molecular weight and the number of branches of the star polymer can be controlled over wide ranges. However, it is difficult to control the preparation because, for example, with an increase in the molecular weight of arm portions, there is a higher risk of causing gelation. Thus, there has been almost no adaptation example of a high-molecular-weight star polymer with the molecular weight of arm portions exceeding 10,000.

Citation List

Patent Literature

PTL 1: JA-A-2005-240048

PTL 2: JP-A-11-116606

Summary of Invention

Technical Problem

From this, although excellent functionalities are expected, under the actual conditions, the properties of coating films, etc., obtained using star polymers have hardly been examined.

Thus, an object of the invention is to provide a star polymer that allows for the formation of a coating film having excellent mechanical properties, a coating material containing the star polymer, a coating film having excellent mechanical properties, and a method for producing a star polymer, according to which the star polymer can be produced. Solution to Problem

The present inventors have conducted extensive research to solve the above problems. As a result, they have found that when each arm portion of a star-shaped polymer has a functional group at a distal end thereof, the arm portion has a number average molecular weight of 10,000 or more as measured by gel permeation chromatography (GPC (RI) ) , and further the star polymer has a number average molecular weight of 100,000 or more as measured by gel permeation chromatography (GPC (RI) ) , the above problems can be solved, and thus accomplished the invention.

That is, the invention encompasses the following aspects.

[1] A star polymer including:

a core portion; and

an arm portion that is a polymer chain attached to the core portion,

the star polymer being configured such that

the arm portion has a functional group at a distal end thereof,

the arm portion has a number average molecular weight of 10,000 or more as measured by gel permeation chromatography (GPC (RI) ) , and

the star polymer has a number average molecular weight of 100,000 or more as measured by gel permeation chromatography (GPC (RI) ) .

[2] The star polymer according to [1] , wherein the number of said arm portions in the star polymer is 10 or more.

[3] The star polymer according to [1] or [2] , wherein the functional group is a hydroxyl group or a carboxyl group.

[4]The star polymer according to any one of [1] to [3] , wherein the functional group is derived from a polymerization initiating end in living radical polymerization.

[5] The star polymer according to any one of [1] to [4] , wherein the arm portion has a first block located on a distal end side and a second block located on a core portion side and attached to the core portion.

[6] The star polymer according to [5] , wherein the glass transition temperature of the second block is lower than the glass transition temperature of the first block.

[7] The star polymer according to [6] , wherein the difference (Tg1 -Tg2) between the glass transition temperature of the first block (Tg1) and the glass transition temperature of the second block (Tg2) is 50℃ or more.

[8] The star polymer according to any one of [1] to [7] , wherein the core portion has a polyfunctional vinyl compound as a constituent component.

[9] The star polymer according to any one of [1] to [8] , wherein the arm portion has a monofunctional vinyl compound as a constituent component.

[10] A coating material including the star polymer according to any one of [1] to [9] .

[11] A coating film formed from the coating material according to [10] .

[12] A method for producing a star polymer, for producing the star polymer according to any one of [1] to [9] by living radical polymerization,

the method for producing a star polymer including:

a step in which a living polymer that serves as the arm portion is synthesized; and

a step in which a polyfunctional vinyl compound is allowed to react with the living polymer.

Advantageous Effects of Invention

According to the invention, a star polymer that allows for the formation of a coating film having excellent mechanical properties can be provided.

In addition, according to the invention, a coating material containing a star polymer can be provided.

In addition, according to the invention, a coating film having excellent mechanical properties can be provided.

Description of Embodiments

Hereinafter, the star polymer, the coating film, the coating material, and the method for producing a star polymer of the invention will be described in detail. However, the following description of constituent elements is an example as a mode for carrying out the invention, and the invention is not limited to their contents.

(Star Polymer)

The star polymer of the invention has a core portion and an arm portion.

The arm portion is attached to the core portion.

Usually, in the star polymer, a plurality of arm portions are attached to the core portion. The plurality of arm portions extend radiately from the core portion, for example.

The core portion has, as a constituent component, a polyfunctional vinyl compound having two or more polymerizable vinyl groups, for example. The core portion is a reactant of a vinyl compound having a polyfunctional vinyl compound, for example. As used herein, as polymerizable vinyl groups, for example, a vinyl group, an acryloyloxy group, a methacryloyloxy group, an allyl group, and the like can be mentioned.

As polyfunctional vinyl compounds, for example, the following compounds can be mentioned.

(1) Aromatic vinyl-based hydrocarbons

(2) Vinyl-based hydrocarbons

(3) Ester group-containing vinyl-based monomers

(4) Sulfone group-containing vinyl-based monomers, vinyl-based sulfuric acid monoesterified products, and salts thereof

(5) Phosphoric acid group-containing vinyl-based monomers

(6) Hydroxyl group-containing vinyl-based monomers

(7) Nitrogen-containing vinyl-based monomers

(8) Halogen element-containing vinyl-based monomers

(9) Carboxyl group-containing vinyl-based monomers and salts thereof

(10) Silicone-containing vinyl-based monomers

As aromatic vinyl-based hydrocarbons in (1) , for example, o-divinylbenzene, m-divinylbenzene, p-divinylbenzene, divinyltoluene, 1, 4-diisopropenylbenzene, trivinylbenzene, and the like can be mentioned.

As vinyl-based hydrocarbons in (2) , for example, isoprene, butadiene, 3-methyl-1, 2-butadiene, 2, 3-dimethyl-1, 3-butadiene, pentadiene, hexadiene, octadiene, 1, 3, 5-hexatriene, cyclopentadiene, cyclohexadiene, trivinylcyclohexane, and the like can be mentioned.

As ester group-containing vinyl-based monomers in (3) , for example, diallyl maleate, diallyl phthalate, divinyl adipate, diallyl adipate, divinyl fumarate, divinyl maleate, divinyl itaconate, vinyl cinnamate, vinyl crotonate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, 1, 2-cyclohexanediol di (meth) acrylate, 1, 3-cyclohexanediol di (meth) acrylate, 1, 4-cyclohexanediol di (meth) acrylate, vinyl (meth) acrylate, polyethylene glycol (molecular weight: 300) di (meth) acrylate, polypropylene glycol (molecular weight: 500) diacrylate, and the like can be mentioned.

As sulfone group-containing vinyl-based monomers, vinyl-based sulfuric acid monoesterified products, and salts thereof in (4) , for example, divinyl sulfide, divinyl sulfone, divinyl sulfoxide, diallyl disulfide, and the like can be mentioned.

As phosphoric acid group-containing vinyl-based monomers in (5) , for example, triallyl phosphoric acid ester, tri (4-vinylphenyl) phosphoric acid ester, tri (4-vinylbenzyl) phosphoric acid ester, diallyl methyl phosphoric acid ester, di (4-vinylphenyl) methyl phosphoric acid ester, di (4-vinylbenzyl) methyl phosphoric acid ester, diallyl phenyl phosphate, and the like can be mentioned.

As hydroxyl group-containing vinyl-based monomers in (6) , for example, divinyl glycol (1, 5-hexadiene-3, 4-diol) , 1, 2-divinyloxy-3-propanol, 1, 3-divinyloxy-2-propanol, and the like can be mentioned.

As nitrogen-containing vinyl-based monomers in (7) , for example, diallylamine, triallylamine, diallyl isocyanurate, diallyl cyanurate, 1-cyanobutadiene, methylene bisacrylamide, bismaleimide, and the like can be mentioned.

As halogen element-containing vinyl-based monomers in (8) , for example, 1, 4-divinylperfluorobutane, chloroprene, diallylamine hydrochloride, and the like can be mentioned.

As carboxyl group-containing vinyl-based monomers and salts thereof in (9) , for example, carboxyl group-containing vinyl-based monomers such as monoallyl maleate, monoallyl phthalate, monovinyl fumarate, monovinyl maleate, and monovinyl itaconate, as well as alkali metal salts and alkaline earth metal salts thereof, and the like can be mentioned. As alkali metal salts, for example, sodium salts, potassium salts, and the like can be mentioned. As alkaline earth metal salts, for example, calcium salts, magnesium salts, and the like can be mentioned.

As silicone-containing vinyl-based monomers in (10) , specifically, for example, divinyldimethylsilane, 1, 3-divinyltetramethyldisiloxane, 1, 1, 3, 3-tetramethyl-1, 3-divinyldisiloxane, and the like can be mentioned.

The polyfunctional vinyl compound may have a heteroatom other than an oxygen atom or may have no heteroatom other than an oxygen atom.

For example, the polyfunctional vinyl compound may have a nitrogen atom or may have no nitrogen atom.

For example, the polyfunctional vinyl compound may have a sulfur atom or may have no sulfur atom.

For example, the polyfunctional vinyl compound may have a halogen atom or may have no halogen atom.

The core portion may contain, as constituent components, other vinyl compounds in addition to the polyfunctional vinyl compound. As other vinyl compounds, for example, the monofunctional vinyl compounds described below can be mentioned.

The proportion of the polyfunctional vinyl compound relative to the polymerizable vinyl group-containing vinyl compound constituting the core portion is not particularly limited, but is preferably 5 to 100 mol%, more preferably 20 to 100 mol%, and particularly preferably 50 to 100 mol%. Within such a range, the core portion of the star polymer has a spherical form that is advantageous in suppressing the entanglement between molecules constituting the core portion of the star polymer; therefore, this is preferable.

The proportion of monomers constituting the core portion in the star polymer is not particularly limited, but is preferably 10 to 99 mol%based on the total monomers constituting the star polymer.

The arm portion is a polymer chain. The polymer chain is usually linear.

The arm portion has a functional group at the distal end. Here, “distal end” refers to, of both ends of an arm portion, an end on the opposite side from the core portion-side end.

The arm portion is attached to the core portion at one end of the arm portion.

The functional group is not particularly limited, and, for example, a hydroxyl group, a carboxyl group, an epoxy group, a vinyl group, an allyl group, a γ-lactone group, and the like can be mentioned.

In the star polymer, when the arm portion has a functional group at the distal end, a coating film having excellent mechanical properties is obtained. Specifically, in the case where a coating film is formed using a star polymer having a functional group at the distal end of each arm portion, as compared with the case where a coating film is formed using a star polymer having substantially the same molecular weight and having no functional group at the distal end of each arm portion, a coating film having more excellent mechanical properties can be obtained.

The functional group at the distal end of an arm portion is not a functional group derived from the monomer that is the main component of the arm portion.

The functional group is a functional group derived from the polymerization initiating end in living radical polymerization, for example.

The arm portion has, as a constituent component, a monofunctional vinyl compound having one polymerizable vinyl group.

As monofunctional vinyl compounds, for example, (meth) acrylic acid compounds, (meth) acrylamide compounds, styrenes, allyl esters, vinyl ethers, vinyl esters, crotonic acid esters, and the like can be mentioned.

As (meth) acrylic acid compounds, for example, (meth) acrylic acid and (meth) acrylic acid esters can be mentioned.

As (meta) acrylic acid esters, for example, aliphatic (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, n-octadecyl (meth) acrylate, and isooctadecyl (meth) acrylate; alicyclic (meth) acrylic acid esters such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate; aromatic (meth) acrylic acid esters such as benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and phenyl (meth) acrylate, and the like can be mentioned.

In addition, as amino group-containing (meth) acrylic acid esters, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, N-tert-butylaminoethyl (meth) acrylate, (meth) acryloxyethyl trimethyl ammonium chloride, and the like can be mentioned.

As (meth) acrylamide compounds, for example, (meth) acrylamide; (meth) acrylonitrile; N-mono-substituted (meth) acrylamide monomers such as N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, and dimethylaminopropyl (meth) acrylamide; N, N-di-substituted (meth) acrylamide monomers such as N- (meth) acryloyl morpholine, N- (meth) acryloyl pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloyl pyrrolidine, N- (meth) acryloyl-4-piperidone, N, N-dimethyl (meth) acrylamide, and N, N-diethyl (meth) acrylamide, and the like can be mentioned.

As styrenes, for example, styrene, tert-butoxystyrene, α-methyl-tert-butoxystyrene, 4- (1-methoxyethoxy) styrene, 4- (1-ethoxyethoxy) styrene, adamantyloxystyrene, 4- (2-methyl-2-adamantyloxy) styrene, 4- (1-methylcyclohexyloxy) styrene, trimethylsilyloxystyrene, dimethyl-tert-butylsilyloxystyrene, tetrahydropyranyloxystyrene, benzylstyrene, trifluoromethylstyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene, vinylnaphthalene, and the like can be mentioned.

As allyl esters, for example, allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palminate, allyl stearate, allyl benzoate, allyl acetoacetate, allyl lactate, allyloxyethanol, and the like can be mentioned.

As vinyl ethers, for example, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2, 2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxyethyl vinyl ether, diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl-2, 4-dichlorophenyl ether, vinyl naphthyl ether, vinyl anthranil ether, and the like can be mentioned.

As vinyl esters, for example, vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxy acetate, vinyl butoxy acetate, vinyl phenyl acetate, vinyl acetoacetate, vinyl lactate, vinyl-β-phenyl butyrate, vinyl cyclohexyl carboxylate, and the like can be mentioned.

As crotonic acid esters, for example, butyl crotonate, hexyl crotonate, glycerin monocrotonate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, dimethylmalate, dibutyl fumarate, maleic anhydride, maleimide, acrylonitrile, methacrylonitrile, maleilonitrile, and the like can be mentioned.

The monofunctional vinyl compound may have a heteroatom other than an oxygen atom or may have no heteroatom other than an oxygen atom.

For example, the monofunctional vinyl compound may have a nitrogen atom or may have no nitrogen atom.

For example, the monofunctional vinyl compound may have a sulfur atom or may have no sulfur atom.

For example, the monofunctional vinyl compound may have a halogen atom or may have no halogen atom.

It is preferable that the arm portion has a first block located on a distal end side and a second block located on a core portion side and attached to the core portion. Here, “distal end” refers to, of both ends of an arm portion, an end on the opposite side from the core portion-side end.

Then, it is preferable that the glass transition temperature of the second block (Tg2) is lower than the glass transition temperature of the first block (Tg1) . As a result, a coating film having more excellent mechanical properties can be obtained.

In the case where the glass transition temperature of the second block (Tg2) is lower than the glass transition temperature of the first block (Tg1) , there is no particular lower limit on the difference (Tg1 -Tg2) between the glass transition temperature of the first block (Tg1) and the glass transition temperature of the second block (Tg2) as long as it is more than 0℃, but the difference (Tg1 -Tg2) is preferably 50℃ or more, more preferably 100℃ or more, and particularly preferably 150℃ or more. There is no particular upper limit on the difference (Tg1 -Tg2) , but the difference (Tg1 -Tg2) is preferably 200℃ or less, more preferably 190℃ or less, and particularly preferably 175℃ or less.

There is no particular lower limit on Tg1 of the first block, but Tg1 is preferably 50℃ or more, more preferably 75℃or more, and particularly preferably 100℃ or more.

There is no particular upper limit on Tg1 of the first block, but Tg1 is preferably 150℃ or less, more preferably 140℃ or less, and particularly preferably 130℃ or less.

There is no particular lower limit on Tg2 of the second block, but Tg2 is preferably -100℃ or more, more preferably -85℃ or more, and particularly preferably -70℃ or more.

There is no particular upper limit on Tg2 of the second block, but Tg2 is preferably 30℃ or less, more preferably 0℃or less, and particularly preferably -30℃ or less.

The glass transition temperature (Tg) of each block can be calculated from Tg of the homopolymer of the monofunctional vinyl compound constituting each block.

For example, in the case where the monofunctional vinyl compound constituting the block is a single kind of compound, Tg of the homopolymer of the monofunctional vinyl compound is Tg of the block.

In addition, for example, in the case where the block is a random copolymer, and two or more kinds of monofunctional vinyl compounds constitute the block, Tg of the block can be obtained from differential scanning calorimetry, and can also be calculated by the following formula using Tg of the homopolymer of each monomer and its volume fraction in the polymer.

[Equation 1]

1/Tg = w1/Tg1 + w2/Tg2 + …

(In the formula, Tg represents the glass transition temperature of the block, Tg1 represents the glass transition temperature of the homopolymer of the monomer 1, Tg2 represents the glass transition temperature of the homopolymer of the monomer 2, w1 represents the volume fraction of the monomer 1, and w2 represents the volume fraction of the monomer 2. )

The mass ratio between the first block and the second block (first block: second block) is not particularly limited, but is, in terms of the balance of mechanical properties, preferably 5: 95 to 95: 5, more preferably 10: 90 to 70: 30, and particularly preferably 25: 75 to 55: 45.

The first block and the second block each independently have, as a constituent component, a monofunctional vinyl compound having one polymerizable vinyl group.

The first block and the second block may each independently have a single kind of monofunctional vinyl compound as a constituent component, or may also have two or more kinds of monofunctional vinyl compounds as constituent components.

The number average molecular weight (Mn) of the arm portion measured by gel permeation chromatography (GPC (RI) ) is 10,000 or more, preferably 12,000 or more, and more preferably 15,000 or more.

In order to obtain a coating film having excellent mechanical properties, in the star polymer, the number average molecular weight (Mn) of the arm portion is 10,000 or more. When the number average molecular weight (Mn) of the arm portion is less than 10,000, a coating film having excellent mechanical properties cannot be obtained.

There is no particular upper limit on the number average molecular weight (Mn) , and the number average molecular weight (Mn) may be 100,000 or less, 60,000 or less, or 50,000 or less.

[GPC (RI) Measurement]

The number average molecular weight (Mn) by a GPC (RI) measurement method can be determined by the following GPC (RI) measurement method.

Measuring apparatus: High-performance GPC apparatus ( “HLC-8220GPC” manufactured by Tosoh Corporation)

Column: Guard column HXL-H manufactured by Tosoh Corporation

+ TSKgel G5000HXL manufactured by Tosoh Corporation

+ TSKgel G4000HXL manufactured by Tosoh Corporation

+ TSKgel G3000HXL manufactured by Tosoh Corporation

+ TSKgel G2000HXL manufactured by Tosoh Corporation

Detector: RI (differential refractometer)

Data processing: SC-8010 manufactured by Tosoh Corporation

Measurement conditions: Column temperature: 40℃

Solvent: Tetrahydrofuran

Flow rate: 1.0 ml/min

Standard: Polystyrene

Sample: Prepared by filtering a tetrahydrofuran solution having a resin solids content of 0.5 mass%through a microfilter (100 μl)

In the star polymer, it is difficult to measure only the molecular weight of the arm portion. Thus, the number average molecular weight of the arm portion can be determined, for example, upon the synthesis of the arm portion by living radical polymerization, by subjecting the arm portion alone to the method described above.

The mass ratio between the core portion and the arm portion (core portion: arm portion) is not particularly limited, but is preferably 1: 99 to 99: 1, more preferably 1: 99 to 50: 50, still more preferably 3: 97 to 40: 60, and particularly preferably 5: 95 to 20 to 80.

The number average molecular weight (Mn) of the star polymer measured by gel permeation chromatography (GPC (RI) ) is 100,000 or more, preferably 120,000 or more, more preferably 150,000 or more, and particularly preferably 200,000 or more.

In order to obtain a coating film having excellent mechanical properties, the number average molecular weight (Mn) of the star polymer is 100,000 or more. When the number average molecular weight (Mn) of the star polymer is less than 100,000, a coating film having excellent mechanical properties cannot be obtained.

There is no particular upper limit on the number average molecular weight (Mn) , and the number average molecular weight (Mn) may be 1,000,000 or less, 800,000 or less, or 700,000 or less.

The weight average molecular weight (Mw) of the star polymer measured by gel permeation chromatography (GPC (RI) ) is not particularly limited, but is preferably 100,000 or more, more preferably 120,000 or more, still more preferably 150,000 or more, and particularly preferably 200,000 or more.

There is no particular upper limit on the weight average molecular weight (Mw) , and the weight average molecular weight (Mw) may be 2,000,000 or less, 1,500,000 or less, or 1,250,000 or less.

The polydispersity (PDI, Mw/Mn) of the star polymer is not particularly limited, and may be 1.05 or more, or may also be 1.10 or more. There is no particular upper limit on the polydispersity, and the polydispersity may be 2.50 or less, or may also be 2.25 or less.

The number of arm portions in the star polymer is not particularly limited, but it is preferable that the number of arm portions determined by the following formula is 10 or more. In addition, the number is preferably 50 or less, more preferably 40 or less, and particularly preferably 30 or less.

[Equation 2]

The method for producing a star polymer is not particularly limited, but it is preferable that the star polymer is produced by controlled radical (living radical) polymerization. It is particularly preferable that the star polymer is produced by ATRP (Atom Transfer Radical Polymerization) or RAFT polymerization (Reversible Addition/Fragmentation Chain Transfer Polymerization) . Through controlled radical (living radical) polymerization such as ATRP or RAFT polymerization, polymerization progresses linearly while preventing the recombination of growing radicals or disproportionation. As a result, a polymer with narrow molecular weight distribution can be precisely synthesized.

The distal end of the arm portion of the star polymer has, for example, a polymerization initiating end in living radical polymerization.

For example, in the case where the star polymer is produced by ATRP, the distal end of the arm portion has a residue resulting from the radical cleavage of an organic halogen compound.

In addition, for example, in the case where the star polymer is produced by RAFT polymerization, the distal end of the arm portion has a residue resulting from the thermal cleavage of a radical polymerization initiator or a residue resulting from the cleavage of a chain transfer agent. Incidentally, the “polymerization initiating end in living radical polymerization” includes not only the initiating end of a polymer chain formed by a growth reaction caused by radicals resulting from the thermal cleavage of a radical polymerization initiator, but also the initiating end of a polymer chain formed by a growth reaction caused by radicals resulting from the cleavage of a chain transfer agent. In the case where the star polymer is produced by RAFT polymerization, the functional group described above is usually derived from a chain transfer agent. In this respect, in the star polymer, the functional group at the distal end of an arm portion does not have to be present at the distal ends of all arm portions. The functional group just needs to be contained in a distal end derived from a chain transfer agent, for example, and may or may not be contained in a distal end derived from a radical polymerization initiator.

(Method for Producing Star Polymer)

The method for producing a star polymer of the invention includes a step of synthesizing a living polymer and a reaction step, and further includes other steps as necessary.

The method for producing a star polymer is a method for producing a star polymer by living radical polymerization.

In the step of synthesizing a living polymer, a living polymer that serves as an arm portion is synthesized. The living polymer that serves as an arm portion has a first block and a second block, for example.

The living polymer is synthesized by ATRP or RAFT polymerization, which is living radical polymerization, for example.

In ATRP, an organic halogen compound is used as a polymerization initiator, and a transition metal complex, such as a copper (I) complex, is used as a catalyst. In addition, as necessary, a ligand is used.

In ATRP, the carbon-halogen bond of the organic halogen compound is radically cleaved, the halogen atom moves onto the metal atom of the catalyst, and the radicals of the polymerization initiator generated are added to the double bond of a vinyl monomer. The radical active species newly generated by the addition become dormant species as a result of the abstraction of the halogen atom on the metal atom of the catalyst. Although the radical active species and the dormant species are in equilibrium, the equilibrium is skewed heavily towards to the dormant species, and the end of a radical active species, which is present at a lower concentration, is added to the vinyl monomer, whereby the polymer grows.

As organic halogen compounds serving as polymerization initiators, for example, ethyl 2-bromoisobutyrate, 2-bromo-2-methylprobionyl bromide, 2-carbobutoxy-2-bromopropane, ethyl 2-bromo-2-methylpropionate, and the like can be mentioned.

Here, when a polymerization initiator having a functional group is used, a star polymer having an arm that has a functional group at the distal end can be prepared in a simple manner.

As polymerization initiators having a functional group, for example, the following polymerization initiators can be mentioned.

As polymerization initiators having a hydroxyl group, for example, 2, 3-dihydroxypropyl 2-bromoisobutyrate and 2-hydroxyethyl 2-bromoisobutyrate can be mentioned.

As polymerization initiators having a carboxyl group, for example, 4- (2- ( (2-bromopropanoyl) (oxy) ethoxy) benzoic acid can be mentioned.

As polymerization initiators having an epoxy group, for example, oxiran-2-ylmethyl-bromopropanate can be mentioned.

As polymerization initiators having an allyl group, for example, allyl-2-bromopropanate can be mentioned.

As polymerization initiators having a vinyl group, for example, vinyl-2-chloroacetate can be mentioned.

As catalysts, for example, copper (I) chloride, copper (II) chloride, copper (I) bromide, copper (II) bromide, chloro (indenyl) bis (triphenylphosphine) ruthenium (II) (dichloromethane adduct) , chloro (indenyl) bis (η5-pentamethylcyclopentadiene) [bis (trip henylphosphine) ] ruthenium (II) , and the like can be mentioned.

Ligands are used for enhancing the catalytic activity of a copper compound, for example. As ligands, for example, 2, 2’-bipyridyl and derivatives thereof; 1, 10-phenanthroline and derivatives thereof; polyamines such as tetramethylethylenediamine, pentamethyldiethylenetriamine, and tris [2- (dimethylamino) ethyl] amine, and the like can be mentioned.

As these organic halogen compounds and catalysts, commercially available reagents manufactured by Sigma-Aldrich, Tokyo Chemical Industry Co., Ltd., FUJIFILM Wako Pure Chemical Corporation, and the like can be used.

In RAFT polymerization, a reaction involving RAFT equilibrium is added to the general free radical polymerization of a substituted monomer, and the polymerization reaction is advanced by a reversible chain transfer reaction through a chain transfer agent (RAFT agent) .

As the chain transfer agent (RAFT agent) used in RAFT polymerization, for example, it is preferable to use a thiocarbonylthio compound, such as dithioester, dithiocarbamate, trithiocarbonate, or xanthate, or a halogen compound having a chloro (Cl) group, a bromo (Br) group, or an iodo (I) group.

As chain transfer agents (RAFT agents) , for example, 4-cyano-4- (dodecylsulfanylthiocarbonyl) sulfanylpentanoic acid, 2-cyano-2-propyl benzodithioate, cyanomethyl methyl (1-phenyl) carbodithioate, 4-cyano-4- (phenylcarbonothioylthio) pentanoic acid, 2-cyano-2-propyl dodecyltrithiocarbonate, 2- (dodecylthiocarbonothioylthio) -2-methylpropionic acid, cyanomethyl dodecyl trithiocarbonate, and the like can be mentioned.

As chain transfer agents (RAFT agents) , commercially available reagents manufactured by Sigma-Aldrich, Tokyo Chemical Industry Co., Ltd., FUJIFILM Wako Pure Chemical Corporation, and the like can be used. The chain transfer agent (RAFT agent) can be suitably selected according to the monomer.

As radical polymerization initiators used in RAFT polymerization, for example, azo compound polymerization initiators such as azobisisobutyronitrile (AIBN) , 1, 1’-azobis (cyclohexanecarbonitrile) , 2, 2’-azobis (2-methylpropionitrile) , 4, 4’-azobis (4-cyanopropionate) , and (2RS, 2’RS) -azobis (4-methoxy-2, 4-dimethylvaleronitrile) , peroxide polymerization initiators such as benzoyl peroxide, and the like can be mentioned.

The polymerization initiator, which is an initiator component used in ATRP polymerization, has the functional group described above at the site that becomes a polymerization initiating end upon polymerization.

The chain transfer agent, which is an initiator component used in RAFT polymerization, has the functional group described above at the site that becomes a polymerization initiating end upon polymerization.

When a living polymer that serves as an arm portion is synthesized by living radical polymerization using such a polymerization initiator or chain transfer agent, a functional group can be introduced at the distal end of an arm portion of a star polymer.

The polymerization initiator or chain transfer agent used as an initiator component may be a synthesized product or may also be a commercially available product.

In the step of synthesizing a living polymer, for example, through the precise radical polymerization such as ATRP or RAFT polymerization described above, a monofunctional vinyl compound is heated and polymerized in the presence of a solvent, whereby a living polymer that serves as an arm portion can be obtained.

The polymerization can be performed, for example, by introducing nitrogen at room temperature to cause deoxidization, followed by heating with stirring until the temperature inside the system reaches 50 to 100℃, and then maintaining the temperature at 50 to 100℃ for 3 to 24 hours.

In the step of synthesizing a living polymer, for example, a monofunctional vinyl compound constituting a first block is polymerized, and then a monofunctional vinyl compound constituting a second block is polymerized, whereby a living polymer that serves as an arm portion can be obtained.

In the case where the step of synthesizing a living polymer is performed through ATRP, the step of synthesizing a living polymer can be performed as follows, for example. First, an organic halogen compound, a catalyst, a ligand, a monofunctional vinyl compound constituting a first block, and a solvent are added into a reactor and mixed. Subsequently, nitrogen is blown into the system to remove dissolved oxygen in the system, and then the inside of the system is heated to polymerize the monofunctional vinyl compound, thereby giving a first block. Subsequently, without the growing end of the obtained polymer being deactivated, a monofunctional vinyl compound constituting a second block is added into the reactor to add the monofunctional vinyl compound to the growing end of the polymer, and further the monofunctional vinyl compound is addition-polymerized, thereby giving a second block.

In the case where the step of synthesizing a living polymer is performed through RAFT, the step of synthesizing a living polymer can be performed as follows, for example. First, a RAFT agent, a radical polymerization agent (e.g., azo-based polymerization initiator) , a monofunctional vinyl compound constituting a first block, and a solvent are added into a reactor and mixed. Subsequently, nitrogen is blown into the system to remove dissolved oxygen in the system, and then the inside of the system is heated to polymerize the monofunctional vinyl compound, thereby giving a first block. Subsequently, without the growing end of the obtained polymer being deactivated, a monofunctional vinyl compound constituting a second block is added into the reactor to add the monofunctional vinyl compound to the growing end of the polymer, and further the monofunctional vinyl compound is addition-polymerized, thereby giving a second block.

The monofunctional vinyl compound that constitutes a first block may be a single kind of compound, or it is also possible to use two or more kinds.

The monofunctional vinyl compound that constitutes a second block may be a single kind of compound, or it is also possible to use two or more kinds.

As monofunctional vinyl compounds, for example, the monofunctional vinyl compounds mentioned as examples in the description of the star polymer of the invention can be mentioned.

In the reaction step, a polyfunctional vinyl compound is allowed to react with a living polymer.

The reaction step is performed as follows, for example. Without the growing end of the living polymer being deactivated, a polyfunctional vinyl compound is added into the reactor, and the living polymer is allowed to react with the polyfunctional vinyl compound. As a result of the polymerization of the polyfunctional vinyl compound in the presence of the living polymer, a core portion is formed, and, at the same time, the living polymer is attached to the core portion at the growing end, whereby a star polymer is obtained.

In the reaction step, due to the influence of interactions such as hydrogen bonding between the functional groups at the distal ends of arm portions, it may become difficult to increase the number of branches or adjust the molecular weight to the desired predetermined value. By adding an additive simultaneously with the addition of the polyfunctional vinyl compound for the purpose of reducing the influence of interactions between functional groups and obtaining a star polymer having a desired number of branches and molecular weight, the influence of interactions between functional groups can be reduced. As such additives, hydrophilic solvents are preferable, and, for example, butyl cellosolve, 1-methoxypropanol, 1-ethoxy-2-propanol, and the like can be mentioned.

In ATRP polymerization, the distal end of an arm portion usually contains a group derived from the organic halogen compound serving as a polymerization initiator. Such groups include the functional groups described above.

In RAFT polymerization, the distal end of an arm portion usually contains a group derived from the radical polymerization initiator or chain transfer agent (RAFT agent) . For example, groups derived from the chain transfer agent (RAFT agent) include the functional groups described above.

(Coating Material)

The coating material of the invention contains the star polymer of the invention, and further, as necessary, also contains other components such as an organic solvent.

The content of the star polymer in the coating material is not particularly limited.

The organic solvent is not particularly limited, and, for example, ketone solvents, cyclic ether solvents, ester solvents, aromatic solvents, alcohol-based solvents, glycol ether solvents, and the like can be mentioned.

As ketone solvents, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like can be mentioned.

As cyclic ether solvents, for example, tetrahydrofuran, dioxolane, and the like can be mentioned.

As ester solvents, for example, methyl acetate, ethyl acetate, butyl acetate, and the like can be mentioned.

As aromatic solvents, for example, toluene, xylene, and the like can be mentioned.

As alcohol-based solvents, for example, methanol, isopropanol, butanol, and the like can be mentioned.

As glycol ether solvents, for example, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, diethylene glycol monoethyl ether, and the like can be mentioned.

These organic solvents may be used alone, and it is also possible to use two or more kinds together.

An organic solvent is used mainly for the purpose of dissolving the star polymer and adjusting the viscosity of the coating material, but usually it is preferable to adjust the nonvolatile content within a range of 30 to 90 mass%. The coating material of the invention has a relatively low viscosity. Therefore, as compared with usual acrylic acrylate monomers having high molecular weights, for example, the amount of organic solvent used can be reduced.

The coating material may also contain, as other components, for example, additives generally used for coating materials, such as UV absorbers, antioxidants, silicone-based additives, fluorine-based additives, organic beads, antistatic agents, silane coupling agents, inorganic fine particles, inorganic fillers, rheology control agents, defoaming agents, antifogging agents, and colorants.

As UV absorbers, for example, triazine derivatives, 2- (2’-xanthenecarboxy-5’-methylphenyl) benzotriazole, 2- (2’-o-nitrobenzyloxy-5’-methylphenyl) benzotriazole, 2-xanthenecarboxy-4-dodecyloxybenzophenone, 2-o-nitrobenzyloxy-4-dodecyloxybenzophenone, and the like can be mentioned.

As triazine derivatives, for example, 2- [4- { (2-hydroxy-3-dodecyloxypropyl) oxy} -2-hydroxyphenyl] -4, 6-bis (2, 4-dimethylphenyl) -1, 3, 5-triazine, 2- [4- { (2-hydroxy-3-tridecyloxypropyl) oxy} -2-hydroxyphenyl] -4, 6-bis (2, 4-dimethylphenyl) -1, 3, 5-triazine, and the like can be mentioned.

As antioxidants, for example, hindered phenol-based antioxidants, hindered amine-based antioxidants, organic sulfur-based antioxidants, phosphoric acid ester-based antioxidants, and the like can be mentioned.

As silicone-based additives, for example, polyorganosiloxanes having an alkyl group or a phenyl group, polydimethylsiloxanes having a polyether-modified acrylic group, polydimethylsiloxanes having a polyester-modified acrylic group, and the like can be mentioned.

As polyorganosiloxanes having an alkyl group or a phenyl group, for example, dimethylpolysiloxane, methylphenylpolysiloxane, cyclic dimethylpolysiloxane, methylhydrogenpolysiloxane, polyether-modified dimethylpolysiloxane copolymers, polyester-modified dimethylpolysiloxane copolymers, fluorine-modified dimethylpolysiloxane copolymers, amino-modified dimethylpolysiloxane copolymers, and the like can be mentioned.

As fluorine-based additives, “MEGAFACE” series manufactured by DIC Corporation and the like can be mentioned.

As organic beads, for example, polymethyl methacrylate beads, polycarbonate beads, polystyrene beads, polyacrylic styrene beads, silicone beads, glass beads, acrylic beads, benzoguanamine-based resin beads, melamine-based resin beads, polyolefin-based resin beads, polyester-based resin beads, polyamide resin beads, polyimide-based resin beads, polyfluoroethylene resin beads, polyethylene resin beads, and the like can be mentioned.

The preferred value of the average particle size of these organic beads is within a range of 1 to 10 μm.

As antistatic agents, for example, pyridinium, imidazolium, phosphonium, ammonium, or lithium salts of bis(trifluoromethanesulfonyl) imide or bis(fluorosulfonyl) imide can be mentioned.

For the purpose of adjusting the viscosity or refractive index, adjusting the color tone of the coating film, or adjusting other coating material properties or coating film properties, the coating material of the invention may further have other components, such as various resins and organic or inorganic particles.

As various resins, for example, acrylic resins, phenol resins, polyester resins, polystyrene resins, urethane resins, urea resins, melamine resins, alkyd resins, epoxy resins, polyamide resins, polycarbonate resins, petroleum resins, fluorine resins, and the like can be mentioned.

As organic or inorganic particles, for example, PTFE (polytetrafluoroethylene) , polyethylene, polypropylene, carbon, titanium oxide, alumina, copper, and silica fine particles and the like can be mentioned.

Methods for producing the coating material of the invention are not particularly limited. For example, a method in which a star polymer and an organic solvent, together with other additives, resins, and the like as necessary, are mixed to give a coating material can be mentioned.

(Coating Film)

The coating film of the invention is formed from the coating material of the invention.

The coating film can be obtained, for example, by stirring a coating material containing a star polymer, an organic solvent, and the like, and then applying the coating material onto a substrate such as a PET film, followed by heat drying.

The coating film of the invention is not particularly limited in application, but is useful as a coating film in a hard coat film. In addition, the coating film of the invention is expected to be applied to soft electronic materials (organic thin-film solar cells, wearables, battery electrolytes, etc. ) , self-healing materials, surface modifiers, functional improvements of existing polymer products (UV resins for coating, binder resins for IJ printer inks, optical resins, etc. ) .

Examples

Hereinafter, the invention will be described in further detail with reference to examples. However, the scope of the invention is not limited to these examples.

[GPC (RI) Measurement]

Column: Guard column HXL-H manufactured by Tosoh Corporation

+ TSKgel G5000HXL manufactured by Tosoh Corporation

+ TSKgel G4000HXL manufactured by Tosoh Corporation

+ TSKgel G3000HXL manufactured by Tosoh Corporation

+ TSKgel G2000HXL manufactured by Tosoh Corporation

Detector: RI (differential refractometer)

Data processing: SC-8010 manufactured by Tosoh Corporation

Measurement conditions: Column temperature: 40℃

Solvent: Tetrahydrofuran

Flow rate: 1.0 ml/min

Standard: Polystyrene

[Preparation of Film, Tensile Test: Method for Measuring Maximum Point Stress and Elongation]

The solids content of each resin solution obtained in the examples and comparative examples was adjusted to 15 mass%. 6.0 g of the resin solution adjusted to 15 mass%was uniformly poured into a PFA petri dish 10 cm in diameter and dried at 120℃ to form a 0.1-mm-thick film. A specimen 5 mm in width and 5 cm in length was cut out from the obtained film, and its tension characteristics were evaluated using a tensile tester (TENSIRON RTG1310 manufactured by A&D Co., Ltd. ) to measure the maximum point stress and elongation.

(Production Example 1] <Preparation of OH Group-Containing Initiator 2, 3-Dihydroxypropyl 2-Bromoisobutyrate (hereinafter abbreviated to DHPBiB) >

Solketal (5.315 g, 0.04 mol) , distilled triethylamine (8.1 g, 0.08 mol) , and distilled THF (tetrahydrofuran) (35 ml) were placed in a 100-ml round bottom flask equipped with a magnetic stirrer, and cooled on ice to 0℃. Next, 2-bromo-2-methylpropionyl bromide (9.3 g, 0.0404 mol) was dissolved in THF (15 ml) and added dropwise to the reaction mixture (round bottom flask) in a nitrogen atmosphere. The mixture was further stirred for 3.5 hours while returning the temperature to room temperature. After the reaction, the mixture was filtered to remove the salt, THF was removed using a rotary evaporator, and then the residue was redissolved in toluene. The organic layer was first washed with 10 mass%HCl, then with a saturated solution of NaHCO ₃, and finally with brine. After toluene was removed, the crude product was isolated as a slightly yellowish oil (70%) and, without further purification, used in the following step.

3 g of the intermediate (2, 2-dimethyl-1, 3-dioxolan-4-yl) methyl 2-bromo-2-methyl propanoate (0.011 mol) , 9 ml of glacial acetic acid, 24 ml of deionized water, and a catalytic amount of 4-methoxybenzene were stirred at 80℃ for 2.5 hours in a nitrogen atmosphere. Next, the solution was cooled to room temperature and neutralized by adding a NaHCO ₃ powder little by little until saturation. Undissolved NaHCO ₃ was filtered away, then 30 mL of ethyl acetate was added for extraction, and the aqueous layer was extracted three times with ethyl acetate. The crude product was obtained from the combined organic layer, and subsequently the solvent was removed as a yellowish oil. Next, the crude product was recrystallized from toluene to give white crystals.

(Example 1] (OH-Terminated Star Polymer Preparation Example-1, MMA/BA Monomer Ratio = 33/67 (Mass Ratio) )

To a 100-ml four-necked flask equipped with a stirrer, a reflux condenser, a temperature sensor, a dropping funnel, and a nitrogen-introducing tube, a catalyst CuCl ₂·2H ₂O (4.8 mg, 0.028 mmol) , a ligand tris (dimethylaminoethyl) amine (Me6TREN) (19.4 mg, 0.084 mmol) , a monomer methyl methacrylate (hereinafter abbreviated to MMA) (5.817 g, 0.0581 mmol) , and a solvent anisole (5.817 g) were added. The mixture was bubbled with nitrogen for 1 hour to remove oxygen remaining in the flask, and then an initiator DHPBiB (0.1688 g, 0.7 mmol) was added into the flask using a syringe in a nitrogen atmosphere. In addition, in the same manner, a reducing agent tin 2-ethylhexanoate Sn (EH) ₂ (0.1134 g, 0.028 mmol) was added to the flask using a syringe in a nitrogen gas atmosphere. The flask was hermetically sealed with a glass stopper and immersed in an oil bath set at 70℃ to initiate polymerization. The mixture was sampled using a syringe at regular time intervals, and the monomer conversion and the polymer molecular weight were determined by gas chromatography (GC) and GPC measurement.

At the time when MMA conversion exceeded 85%, a mixed solution of n-butyl acrylate (hereinafter abbreviated to nBA) (11.7532 g, 0.0917 mol) and anisole (11.7532 g) was added using a syringe in a nitrogen atmosphere. The oil bath was raised to 90℃, and, in the same manner, the mixture was sampled at regular time intervals, and measurement was performed by GC and GPC.

In the same manner, at the time when the nBA conversion exceeded 85%, a mixed solution of divinylbenzene (hereinafter abbreviated to DVB) (2.2783 g, 0.0157 mol) and butyl cellosolve (hereinafter abbreviated to BCS) (30 g) was added to the reaction system, and polymerization was allowed to continue until the reactivity of DVB exceeded 95%. Finally, the reaction system was exposed to air and diluted with BCS to halt the reaction, thereby giving a star polymer composed of a block polymer of MMA and nBA.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 31,240, and the molecular weight of the star polymer was Mw = 925,750. In addition, PDI (Polydispersity, Mw/Mn) of the star polymer was 1.90.

In addition, from these results, the number of arms of the obtained star polymer was calculated by the following formula. The results are shown in Table 2.

[Equation 3]

Next, a 0.1-mm-thick film was prepared from the obtained star polymer solution by a casting method and subjected to a tensile test, and, as a result, it turned out that its film functions were excellent. The results are summarized in Table 2.

(Example 2] (OH-Terminated Star Polymer Preparation Example-2, MMA/BA Monomer Ratio = 33/67 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 1 by the same method as in Example 1.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 17,600, and the molecular weight of the star polymer was Mw = 262,110.

(Example 3] (OH-Terminated Star Polymer Preparation Example-3, MMA/BA Monomer Ratio = 33/67 (Mass Ratio) )

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 21,640, and the molecular weight of the star polymer was Mw = 1,126,660.

(Example 4] (OH-Terminated Star Polymer Preparation Example-6, Use of 2-Hydroxyethyl 2-Bromoisobutyrate (hereinafter abbreviated to HEBiB) in Place of DHPBiB, MMA/BA Monomer Ratio = 33/67 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 1 by the same method as in Example 1, except for that HEBiB (manufactured by Tokyo Chemical Industry Co., Ltd. ) was used as an initiator.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 26,304, and the molecular weight of the star polymer was Mw = 347,670.

(Example 5)

(COOH-Terminated Star Polymer Preparation Example-1, MMA/BA Monomer Ratio = 33/67 (Mass Ratio) )

To a reactor equipped with a stirrer, a reflux condenser, a temperature sensor, a dropping funnel, and a nitrogen-introducing tube, 24.2 g of MMA, 8.8 g of dimethylacrylamide, 0.64 g of a RAFT agent BM1430 (manufactured by Boron Molecular) , 0.11 g of a radical polymerization agent azobisisobutyronitrile, and 33.0 g of a solvent toluene were added, and nitrogen was blown into the system to remove dissolved oxygen from the inside of the system. After it was seen that the oxygen concentration in the system had sufficiently decreased, polymerization was performed at 60℃ for 24 hours.

Next, 77.0 g of nBA and 77.0 g of toluene were added to a dropping funnel, bubbled with nitrogen to remove dissolved oxygen, and then added into the reactor to initiate the polymerization of n-butyl acrylate. Subsequently, polymerization was performed at 60℃ for 6 hours, whereby a block polymer to serve as an arm of a star polymer was prepared.

As a result of measuring the molecular weight of the obtained arm polymer (block polymer) by GPC, Mn = 35,590.

Next, 160 g of toluene was added to a dropping funnel, bubbled with nitrogen to remove dissolved oxygen, and then added into the reactor. Subsequently, 11.0 g of trimethylolpropane triacrylate (BISCOAT 295 manufactured by Osaka Organic Chemical Industry) was added into the reactor while blowing nitrogen, taking care to avoid the introduction of air into the reactor. The reaction temperature was raised to 70℃, and the reaction was continued for 24 hours.

After polymerization, toluene was added to part of the polymerization solution, thereby preparing 50 g of a solution having a solids content of 15 mass%. In a 1-L flask, while stirring with a stirring bar, a mixed solution of 420 g of cyclohexane and 80 g of isopropanol was added to this solution, and, after the solution became homogeneous, 100 g of cyclohexane was added to give a white precipitate. This solution was filtered, then the precipitate was dried, and the precipitate was dissolved in a solution of 40 g of toluene and 5 g of isopropyl alcohol to give a star polymer solution.

As a result of measuring the molecular weight of the obtained star polymer by GPC, a peak of Mw = 479,360 and PDI = 1.35 was formed in the polymer region, indicating that the star polymer was obtained.

(Example 6] (OH-Terminated Star Polymer Preparation Example-4, MMA/BA Monomer Ratio = 50/50 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 3 by the same method as in Example 1.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 20,940, and the molecular weight of the star polymer was Mw = 283,300.

Next, a 0.1-mm-thick film was prepared from the obtained star polymer solution by a casting method and subjected to a tensile test, and, as a result, it turned out that its film functions were excellent. The results are summarized in Table 4.

(Example 7] (OH-Terminated Star Polymer Preparation Example-5, MMA/BA Monomer Ratio = 50/50 (Mass Ratio) )

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 38,360, and the molecular weight of the star polymer was Mw = 894,480.

(Example 8] (OH-Terminated Star Polymer Preparation Example-6, Use of HEBiB in Place of DHPBiB, MMA/BA Monomer Ratio = 50/50 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 3 by the same method as in Example 1, except for that HEBiB was used as an initiator.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 26,089, and the molecular weight of the star polymer was Mw = 398,510.

(Example 9] (OH-Terminated Star Polymer Preparation Example-6, Use of HEBiB in Place of DHPBiB, MMA/BA Monomer Ratio = 50/50 (Mass Ratio) )

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 26,723, and the molecular weight of the star polymer was Mw = 369,760.

(Comparative Example 1) (Comparative Example-1, Star Polymer Without Terminal Functional Group, MMA/BA Monomer Ratio =33/67 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 1 by the same method as in Example 1. As an initiator, ethyl 2-bromoisobutyrate (0.1365 g, 0.7 mmol) was used in place of DHPBiB. Other raw materials were used in the same amounts as in Example 1.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 29,600, which was almost the same as in Example 1.

Next, a 0.1-mm-thick film was prepared from the obtained star polymer solution by a casting method and subjected to a tensile test. The results are summarized in Table 2.

(Comparative Example 2) (Comparative Example-2, Star Polymer Without Terminal Functional Group, MMA/BA Monomer Ratio =33/67 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 1 by the same method as in Example 1. As an initiator, ethyl 2-bromoisobutyrate (EBiB, 0.2341 g, 1.2 mmol) was used in place of DHPBiB. Other raw materials were used in the same amounts as in Example 2.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 14,440, which was almost the same as in Example 2.

(Comparative Example 3) (Comparative Example-3, Star Polymer Without Terminal Functional Group, MMA/BA Monomer Ratio =33/67 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 1 by the same method as in Example 1. As an initiator, ethyl 2-bromoisobutyrate (EBiB, 0.1755 g, 0.9 mmol) was used in place of DHPBiB. Other raw materials were used in the same amounts as in Example 3.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 20,820, which was almost the same as in Example 3.

(Comparative Example 4) (Comparative Example of Star Polymer with Terminal Functional Group OH, MMA/BA Monomer Ratio = 33/67 (Mass Ratio) )

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 9,500, which was not more than 10,000.

(Comparative Example 5) (Comparative Example of Star Polymer with Terminal Functional Group OH, MMA/BA Monomer Ratio = 33/67 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 1 by the same method as in Example 2, except that the polymerization was stopped when the DVB reactivity was 85%. As a result of stoppage at a low DVB reactivity, the residual amount of arm polymer increased. Therefore, methanol was added to the obtained polymer solution to cause reprecipitation, thereby performing purification.

The molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 12,720. Meanwhile, the molecular weight of the obtained star polymer was Mn = 83,980, which was less than 100,000. Also, the number of arms calculated was 8, which was less than 10.

(Comparative Example 6) (Comparative Example-4, Star Polymer Without Terminal Functional Group, MMA/BA Monomer Ratio =50/50 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 1 by the same method as in Example 1. As an initiator, ethyl 2-bromoisobutyrate (EBiB, 0.1755 g, 0.9 mmol) was used in place of DHPBiB. Other raw materials were used in the same amounts as in Example 6.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 17,650, which was almost the same as in Example 6.

Next, a 0.1-mm-thick film was prepared from the obtained star polymer solution by a casting method and subjected to a tensile test. The results are summarized in Table 4.

(Comparative Example 7) (Comparative Example-5, Star Polymer Without Terminal Functional Group, MMA/BA Monomer Ratio =50/50 (Mass Ratio) )

A star polymer was prepared with the feed amounts shown in Table 1 by the same method as in Example 1. As an initiator, ethyl 2-bromoisobutyrate (EBiB, 0.1365 g, 0.7 mmol) was used in place of DHPBiB. Other raw materials were used in the same amounts as in Example 7.

As a result of molecular weight analysis by GPC, the molecular weight of the arm polymer (block polymer before adding DVB to the reaction system) was Mn = 24,310, which was almost the same as in Example 7.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

In Example 1 using a star polymer having a hydroxyl group at the distal end of an arm portion, as compared with Comparative Example 1 using a star polymer having the same level of molecular weight and having no functional group at the distal end of an arm portion, the maximum point stress and the elongation in the tensile test were higher, showing excellent mechanical properties.

In Example 2 using a star polymer having a hydroxyl group at the distal end of an arm portion, as compared with Comparative Example 2 using a star polymer having the same level of molecular weight and having no functional group at the distal end of an arm portion, the maximum point stress and the elongation in the tensile test were higher, showing excellent mechanical properties.

In Example 3 using a star polymer having a hydroxyl group at the distal end of an arm portion, as compared with Comparative Example 3 using a star polymer having the same level of molecular weight and having no functional group at the distal end of an arm portion, the maximum point stress and the elongation in the tensile test were higher, showing excellent mechanical properties.

In Example 6 using a star polymer having a hydroxyl group at the distal end of an arm portion, as compared with Comparative Example 6 using a star polymer having the same level of molecular weight and having no functional group at the distal end of an arm portion, the maximum point stress and the elongation in the tensile test were higher, showing excellent mechanical properties.

In Example 7 using a star polymer having a hydroxyl group at the distal end of an arm portion, as compared with Comparative Example 7 using a star polymer having the same level of molecular weight and having no functional group at the distal end of an arm portion, the maximum point stress and the elongation in the tensile test were higher, showing excellent mechanical properties.

In Comparative Example 4 using a star polymer in which the number average molecular weight of arm portions measured by gel permeation chromatography (GPC (RI) ) was less than 10,000, the obtained coating film was fragile and not able to be subjected to a tensile test.

In Comparative Example 5 using a star polymer whose number average molecular weight measured by gel permeation chromatography (GPC (RI) ) was less than 100,000, the maximum point stress and the elongation in the tensile test were low.

Claims

A star polymer comprising:

a core portion; and

an arm portion that is a polymer chain attached to the core portion,

the star polymer being configured such that

the arm portion has a functional group at a distal end thereof,

the arm portion has a number average molecular weight of 10,000 or more as measured by gel permeation chromatography (GPC (RI) ) , and

the star polymer has a number average molecular weight of 100,000 or more as measured by gel permeation chromatography (GPC (RI) ) .
The star polymer according to claim 1, wherein the number of the arm portions in the star polymer is 10 or more.
The star polymer according to claim 1 or 2, wherein the functional group is a hydroxyl group or a carboxyl group.
The star polymer according to any one of claims 1 to 3, wherein the functional group is derived from a polymerization initiating end in living radical polymerization.
The star polymer according to any one of claims 1 to 4, wherein the arm portion has a first block located on a distal end side and a second block located on a core portion side and attached to the core portion.
The star polymer according to claim 5, wherein the glas s transition temperature of the second block is lower than the glas s transition temperature of the first block.
The star polymer according to claim 6, wherein the difference (Tg1 -Tg2) between the glass transition temperature of the first block (Tg1) and the glass transition temperature of the second block (Tg2) is 50℃ or more.
The star polymer according to any one of claims 1 to 7, wherein the core portion has a polyfunctional vinyl compound as a constituent component.
The star polymer according to any one of claims 1 to 8, wherein the arm portion has a monofunctional vinyl compound as a constituent component.
A coating material comprising the star polymer according to any one of claims 1 to 9.
A coating film formed from the coating material according to claim 10.
A method for producing a star polymer, for producing the star polymer according to any one of claims 1 to 9 by living radical polymerization,

the method for producing a star polymer comprising:

a step in which a living polymer that serves as the arm portion is synthesized; and

a step in which a polyfunctional vinyl compound is allowed to react with the living polymer.