Vinyl polymer, curable resin composition, and cured product

Abstract

Provided is a vinyl polymer having a (meth)acryloyloxy group at a molecular terminal and having a (meth)acrylate salt content of 7% by mass or less.

Description

Vinyl polymers, curable resin compositions, and cured products

[0001] [Cross-reference of related applications] This application claims priority under Japanese Patent Application No. 2024-207089, filed on 28 November 2024, which is incorporated herein by reference in its entirety. This disclosure relates to vinyl polymers, curable resin compositions and cured products.

[0002] For industrial applications, vinyl polymers with crosslinkable functional groups are known. Recently, living radical polymerization, a polymerization method consisting of an initiation reaction and a growth reaction with no side reactions, has become widely used as a method for producing vinyl polymers, as it allows for the synthesis of polymers with well-controlled molecular weight distribution and molecular structure.

[0003] Vinyl polymers having crosslinkable functional groups at their molecular ends are widely used as curable resin compositions for producing cured products in various fields, such as paints, adhesives, sealants, molded articles, and rubber sheets. For example, Patent Document 1 discloses the synthesis of a vinyl polymer having (meth)acryloyl groups at its molecular ends by living radical polymerization, and the use of the obtained vinyl polymer as a resin component in a curable resin composition.

[0004] Japanese Patent Publication No. 2000-72815

[0005] However, the cured vinyl polymer described in Patent Document 1 tends to discolor over time, and its low transparency can be a problem.

[0006] This disclosure is made in view of these circumstances, and its main purpose is to provide a vinyl polymer that can produce a cured product with excellent color resistance and transparency.

[0007] The inventors have conducted diligent research and discovered that in vinyl polymers having (meth)acryloyloxy groups at their molecular termini, when the (meth)acrylate content exceeds a predetermined amount, the cured product obtained using such vinyl polymer tends to discolor over time and has low transparency. Specifically, the present disclosure provides the following vinyl polymer, curable resin composition, and cured product.

[0008] [1] A vinyl polymer having (meth)acryloyloxy groups at the molecular terminus and containing 7% by mass or less of (meth)acrylate salt. [2] The vinyl polymer according to [1], which is a (meth)acrylic polymer. [3] A curable resin composition containing the vinyl polymer according to [1] or [2]. [4] A cured product formed from the curable resin composition according to [3].

[0009] According to the vinyl polymer of this disclosure, a cured product with excellent color resistance and transparency can be obtained.

[0010] The following provides a detailed explanation of this disclosure. In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate. "(meth)acrylo" means acrylo and / or methacrylo.

[0011] Vinyl Polymers The vinyl polymers of this disclosure have (meth)acryloyloxy groups at their molecular ends, and the content of (meth)acrylate salts in the vinyl polymer is 7% by mass or less. The vinyl polymers of this disclosure will be described in detail below. Hereinafter, the vinyl polymers of this disclosure will also be referred to as "vinyl polymer (M)".

[0012] When the content of (meth)acrylate in the vinyl polymer (M) exceeds 7% by mass, the cured product obtained using the vinyl polymer (M) is prone to discoloration over time and has poor transparency. From the viewpoint of obtaining a cured product with superior discoloration resistance and transparency, the content of (meth)acrylate in the vinyl polymer is preferably 5.5% by mass or less, more preferably 5.0% by mass or less, even more preferably 4.0% by mass or less, even more preferably 3.0% by mass or less, even more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less. The lower limit of the content of (meth)acrylate in the vinyl polymer (M) is not particularly limited, and is 0% by mass or more.

[0013] In this specification, the content of (meth)acrylate in the vinyl polymer (M) is: １ This value is calculated from the integrated value measured by 1H-NMR spectroscopy using the following formula: (meth)acrylate content in vinyl polymer = [(integral value derived from (meth)acrylate) × (molecular weight of (meth)acrylate)] / [(integral value derived from constituent monomers) × (molecular weight of constituent monomers)]

[0014] The (meth)acrylate in the vinyl polymer (M) can be represented by the following general formula (1). Here, in general formula (1), R is a hydrogen atom or a methyl group, and Z ＋ CH is a cation. ２ =CR-COO － Z ＋ …(1)

[0015] In (meth)acrylate salts, the counterion (Z) of the (meth)acrylate anion ＋ The cation may be an inorganic cation or an organic cation. Examples of inorganic cations include alkali metal ions such as lithium ions, sodium ions, and potassium ions.

[0016] Examples of organic cations include quaternary ammonium ions and organic cations derived from organic bases. The quaternary ammonium ions constituting the (meth)acrylate are not particularly limited, and the general formula is: N ＋ (R Ａ )４ Examples include polyatomic ions represented by and polyatomic ions having a nitrogen-containing heterocyclic ring. Here, R Ａ Examples of include an alkyl group, an aryl group, and an aralkyl group. In the formula, the four Rs Ａ may be the same or different. Specific examples of quaternary ammonium ions include, for example, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, benzyltrimethylammonium ion, benzyltriethylammonium ion, and hexadecyltrimethylammonium ion, dimethylpiperidinium ion, and cetylpyridinium ion.

[0017] Examples of the organic base include basic compounds having a nitrogen atom and / or a phosphorus atom. Specific examples of the organic base include primary amines such as monoethylamine, monobutylamine, ethanolamine, ethylenediamine, aniline, and N-methylaniline; secondary amines such as diethylamine, dibutylamine, dicyclohexylamine, and diethanolamine; tertiary amines such as trimethylamine, triethylamine, tripropylamine, tetramethylethylenediamine, and N-methylmorpholine; nitrogen-containing heterocyclic amines such as pyridine, pyrrole, and 1-methylpyrrole; guanidines such as guanidine, tetramethylguanidine (TMG), and diphenylguanidine (DPG); amidines such as diazabicyclononene (DBN), diazabicycloundecene (DBU), and 6-dibutylamino-1,8-diazabicyclo[5.4.0]undec-7-ene (DBA-DBU); organic phosphines such as triphenylphosphine (TPP) and 2-tert-butylimino-2-diethylamino-1,3-dimethyl-perhydro-1,3,2-diazaphospholine (BEMP); etc.

[0018] In order to reduce the coloring of the vinyl polymer (M), it is preferable that the content of transition metal atoms derived from (meth) acrylate or the like in the vinyl polymer (M) is as small as possible. Specifically, the content of transition metal atoms in the vinyl polymer (M) is preferably 1000 ppm or less, more preferably 100 ppm or less, still more preferably 10 ppm or less, and particularly preferably 2 ppm or less. In this specification, the "content of transition metal atoms" is the total amount of transition metal atoms contained in the vinyl polymer, and can be quantified by ICP emission spectrometry.

[0019] The vinyl polymer (M) may be a homopolymer obtained by polymerizing one kind of monomer, or may be a copolymer obtained by polymerizing two or more kinds of monomers. The type of copolymer is not particularly limited, and examples include random copolymers, block copolymers, alternating copolymers, and graft copolymers.

[0020] The vinyl monomer constituting the vinyl polymer (M) is not particularly limited, and various vinyl monomers having radical polymerizability can be used. Examples of the vinyl monomer include (meth) acrylate ester compounds, aromatic vinyl compounds, unsaturated carboxylic acids, unsaturated acid anhydrides, hydroxy group-containing vinyl compounds, amino group-containing vinyl compounds, amide group-containing vinyl compounds, alkoxy group-containing vinyl compounds, nitrile group-containing vinyl compounds, maleimide compounds, and the like. As the vinyl monomer, one of these may be used alone, or two or more of them may be used in combination.

[0021] Specific examples of vinyl monomers include the following compounds: (meth)acrylate ester compounds include alkyl (meth)acrylate ester compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, amyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-dodecyl (meth)acrylate, and n-octadecyl (meth)acrylate; Examples include aliphatic cyclic ester compounds of (meth)acrylic acid such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; and aromatic ester compounds of (meth)acrylic acid such as phenyl methacrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, and 3-phenoxypropyl (meth)acrylate.

[0022] Examples of aromatic vinyl compounds include styrene compounds such as styrene, α-methylstyrene, β-methylstyrene, vinylxylene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, p-n-butylstyrene, p-isobutylstyrene, p-t-butylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol, o-isopropenylphenol, o-vinylbenzoic acid, m-vinylbenzoic acid, p-vinylbenzoic acid, and divinylbenzene, as well as vinylnaphthalene and the like.

[0023] As the unsaturated carboxylic acid, examples include (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamic acid, monoalkyl esters of unsaturated dicarboxylic acids (monoalkyl esters of maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.). Examples of the unsaturated acid anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride, etc.

[0024] As the hydroxy group-containing vinyl compound, examples include hydroxyalkyl (meth)acrylate compounds such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; polyalkylene glycol mono(meth)acrylate compounds such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and polyethylene glycol-polypropylene glycol mono(meth)acrylate; unsaturated alcohols such as allyl alcohol; N-substituted maleimide compounds such as N-(4-hydroxyphenyl)maleimide; and hydroxyl group-containing styrene compounds such as o-hydroxystyrene, m-hydroxystyrene, and p-hydroxystyrene.

[0025] As the amino group-containing vinyl compound, examples include dimethylaminomethyl (meth)acrylate, diethylaminomethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 2-(di-n-propylamino)ethyl (meth)acrylate, 2-dimethylaminopropyl (meth)acrylate, 2-diethylaminopropyl (meth)acrylate, 2-(di-n-propylamino)propyl (meth)acrylate, 3-dimethylaminopropyl (meth)acrylate, 3-diethylaminopropyl (meth)acrylate, 3-(di-n-propylamino)propyl (meth)acrylate, etc.

[0026] Examples of amide group-containing vinyl compounds include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and N-methylol(meth)acrylamide. Examples of alkoxy group-containing vinyl compounds include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(n-propoxy)ethyl (meth)acrylate, 2-(n-butoxy)ethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 2-(n-propoxy)propyl (meth)acrylate, and 2-(n-butoxy)propyl (meth)acrylate.

[0027] Examples of nitrile group-containing vinyl compounds include cyanomethyl (meth)acrylate, 1-cyanoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, 2-cyanopropyl (meth)acrylate, 3-cyanopropyl (meth)acrylate, 4-cyanobutyl (meth)acrylate, 6-cyanohexyl (meth)acrylate, 2-ethyl-6-cyanohexyl (meth)acrylate, 8-cyanooctyl (meth)acrylate, meth)acrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, and α-fluoroacrylonitrile.

[0028] Examples of maleimide compounds include maleimides and N-substituted maleimide compounds. Examples of N-substituted maleimide compounds include N-methylmaleimide, N-ethylmaleimide, N-n-propylmaleimide, N-isopropylmaleimide, N-n-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N-pentylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, and N-stearylmaleimide, which are N-alkyl-substituted maleimide compounds; N-cyclopentylmaleimide and N Examples include N-cycloalkyl-substituted maleimide compounds such as cyclohexylmaleimide; N-aralkyl-substituted maleimide compounds such as N-benzylmaleimide; and N-aryl-substituted maleimide compounds such as N-phenylmaleimide, N-(4-hydroxyphenyl)maleimide, N-(4-acetylphenyl)maleimide, N-(4-methoxyphenyl)maleimide, N-(4-ethoxyphenyl)maleimide, N-(4-chlorophenyl)maleimide, and N-(4-bromophenyl)maleimide. In addition to the above compounds, dialkyl esters of unsaturated dicarboxylic acids, vinyl ester compounds, vinyl ether compounds, etc., can also be used as monomers constituting the vinyl polymer (M).

[0029] The vinyl polymer (M) may have (meth)acryloyloxy groups at some of its molecular ends, or it may have (meth)acryloyloxy groups at all of its molecular ends. For example, if the vinyl polymer (M) is a linear polymer, it may have (meth)acryloyloxy groups at only one end, or it may have (meth)acryloyloxy groups at both ends. For the vinyl polymer (M), the number of (meth)acryloyloxy groups per molecule (average value) is, for example, 0.3 or more, and may be between 0.3 and 4.0.

[0030] <Production of Vinyl Polymers> The method for producing vinyl polymers (M) is not particularly limited, as long as a vinyl polymer having (meth)acryloyloxy groups at the molecular termini can be obtained. A method comprising the following first and second steps can be used, as it allows for a high rate of introduction of (meth)acryloyloxy groups at the molecular termini and is easy to produce. First step: A step to obtain a polymer (P) having halogen atoms at the termini and containing structural units derived from vinyl monomers. Second step: A step to react polymer (P) with a carboxylate salt.

[0031] Here, a modified vinyl polymer in which (meth)acryloyloxy groups are introduced at the molecular ends is useful as a curable resin composition for producing cured products in various fields such as paints, adhesives, sealants, molded articles, and rubber sheets. A modified polymer having (meth)acryloyloxy groups at the molecular ends can be obtained, for example, by reacting a polymer (P) with a carboxylate. On the other hand, when a modified polymer having (meth)acryloyloxy groups at the molecular ends is obtained by reacting a polymer (P) with a carboxylate, if a large amount of carboxylate that was not consumed in the reaction remains in the modified polymer as an impurity, the product obtained using that modified polymer may become easily discolored over time or have low transparency. In contrast, the vinyl polymer (M) of this disclosure has (meth)acryloyloxy groups at the molecular ends, and the content of (meth)acrylate is 7% by mass or less, thereby enabling the cured product obtained using the vinyl polymer (M) to have excellent discoloration resistance and transparency. The first and second processes will be explained in detail below.

[0032] <First Step> In the first step, the method of obtaining the polymer (P) is not particularly limited, as long as a vinyl polymer having halogen atoms at its terminals can be obtained. When obtaining the polymer (P) in the first step by polymerizing vinyl monomers, the polymerization method for obtaining the polymer (P) is not particularly limited, and known polymerization methods can be used as appropriate. It is preferable to use a living radical polymerization method, which performs precise polymerization in the presence of a control agent having halogen atoms, because it can produce polymers with a narrow molecular weight distribution and can easily produce polymers with halogen atoms introduced at their terminals. Specifically, among living radical polymerization methods, atom transfer radical polymerization (ATRP method), reversible transfer catalytic polymerization (RTCP method), reversible coordination-mediated polymerization (RCMP method), and iodine transfer polymerization are preferred, and iodine transfer polymerization is more preferred because it is an inexpensive yet highly safe controlled radical polymerization and is highly practical.

[0033] Examples of halogen atoms (hereinafter also referred to as "terminal halogens") that polymer (P) may have at its molecular ends include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Of these, bromine atoms or iodine atoms are preferred, and iodine atoms are particularly preferred, because they allow for a higher rate of introduction of (meth)acryloyloxy groups when modifying the end of polymer (P) using the terminal halogens of polymer (P) in the subsequent second step.

[0034] A (meth)acrylic polymer is preferred for polymer (P) because it can be produced relatively easily by living radical polymerization methods such as iodine transfer polymerization and ATRP, offers a high degree of freedom in monomer selection, and has excellent properties such as flexibility and weather resistance, making it applicable to a wide range of uses. When polymer (P) (and consequently vinyl polymer (M)) is a (meth)acrylic polymer, the amount of (meth)acrylic compound among the monomers constituting the polymer is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, relative to the total amount of monomers constituting the polymer.

[0035] When polymer (P) is a (meth)acrylic polymer, it is more preferable that polymer (P) contains structural units derived from the compound represented by the following general formula (2), as this facilitates the application of living radical polymerization and provides excellent properties such as flexibility and weather resistance. ２ =CR １ -C(=O)-O-(R ２ O) ｎ -R ３ ...(2) (In general formula (2), R １ R represents a hydrogen atom or a methyl group. ２ R represents a linear or branched alkylene group having 2 to 6 carbon atoms. ３ (where n represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms. n represents an integer from 0 to 100.)

[0036] Specific examples of compounds represented by the above general formula (2) include the (meth)acrylic acid ester compounds, alkoxy group-containing vinyl compounds, (meth)acrylate hydroxyalkyl compounds, and polyalkylene glycol mono(meth)acrylate compounds exemplified above. Of these, it is more preferable to include (meth)acrylic acid ester compounds in order to obtain vinyl polymers with good heat resistance and other properties.

[0037] When polymer (P) is obtained by iodine transfer polymerization, polymer (P) can be obtained by polymerizing vinyl monomers (specifically, by living radical polymerization) in the presence of an iodine-based polymerization controller and a radical polymerization initiator. In iodine transfer polymerization, an iodine compound (i.e., an iodine-based polymerization controller) acts as an exchange chain transfer agent for radicals generated by a free radical polymerization initiator, and polymerization proceeds. At this time, the iodine-based polymerization controller functions as a living radical polymerization controller that precisely controls the molecular weight of the polymer in the vinyl monomer polymerization system. This makes it possible to obtain a polymer with a narrow molecular weight distribution.

[0038] The iodine-based polymerization control agent is not particularly limited, as long as it functions as a living radical polymerization control agent that precisely controls the molecular weight and molecular weight distribution of the polymer (P). Examples of iodine-based polymerization control agents include monofunctional control agents having one iodine group in one molecule; difunctional control agents having two iodine groups in one molecule; and polyfunctional control agents having three or more iodine groups in one molecule. For example, by performing polymerization in the presence of a monofunctional control agent, a polymer having an iodine group at one end of the polymer chain can be obtained, and by performing polymerization in the presence of a difunctional control agent, a polymer having iodine groups at both ends of the polymer chain (telechelic polymer) can be obtained. Furthermore, by performing polymerization in the presence of a polyfunctional control agent, a branched polymer having branching corresponding to the number of iodine atoms in one molecule of the iodine-based polymerization control agent can be obtained.

[0039] Specific examples of monofunctional iodine-based polymerization regulators include α-iodoester compounds such as ethyl 2-iodoethyl, ethyl 2-iodopropionate, ethyl 2-iodobutyrate, and ethyl 2-iodoisobutyrate; α-iodocarboxylic acids such as 2-iodoacetic acid, 2-iodopropionic acid, 2-iodobutyrate, and 2-iodoisobutyrate; α-iodlactone compounds such as α-iodo-γ-butyrolactone; α-iodoamide compounds such as 2-iodopropionamide; α-iodonitrile compounds such as 2-iodoacetonitrile and 2-iodopropionitrile; α-iodoketone compounds such as 2-iodoacetophenone; and benzyl iodide compounds such as benzyl iodide, (1-iodoethyl)benzene, and 4-nitrobenzyl iodide.

[0040] Specific examples of bifunctional control agents include 1,4-bis(iodomethyl)benzene, diethyl 2,5-diiodoadipate, 1,4-bis(1'-iodoethyl)benzene, and ethylene glycol bis(2-iodoisobutyrate). Specific examples of polyfunctional control agents include glycerol tris(2-iodoisobutyrate) and 1,3,5-tris(1'-iodoethyl)benzene. As iodine-based polymerization control agents, one of these may be used alone, or two or more may be used in combination.

[0041] The amount of iodine-based polymerization control agent used can be appropriately set according to the molecular weight of the desired vinyl polymer. The amount of iodine-based polymerization control agent used is, for example, 0.001 to 0.5 parts by mass per 100 parts by mass of the total amount of monomers used for polymerization.

[0042] As radical polymerization initiators, known radical polymerization initiators such as azo compounds, organic peroxides, and persulfates can be used. Among these, azo compounds are preferred because they are easy to handle safely and less likely to cause side reactions during radical polymerization. Specific examples of azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitride), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], and 2,2'-azobis(N-butyl-2-methylpropionamide). One type of radical polymerization initiator may be used, or two or more types may be used in combination.

[0043] The amount of radical polymerization initiator used is not particularly limited, but from the viewpoint of obtaining polymers with a smaller molecular weight distribution, it is preferable to use 0.5 mol or less, and more preferably 0.2 mol or less, per mol of iodine-based polymerization regulator. Furthermore, from the viewpoint of stably carrying out the polymerization reaction, the lower limit of the amount of radical polymerization initiator used is preferably 0.01 mol or more, and more preferably 0.05 mol or more, per mol of iodine-based polymerization regulator. The amount of radical polymerization initiator used per mol of iodine-based polymerization regulator is preferably 0.01 to 0.5 mol, and more preferably 0.05 to 0.2 mol.

[0044] The polymerization reaction is preferably carried out in a polymerization solvent using a polymerization solvent known for living radical polymerization. In the case of solution polymerization, the solvent, monomer and iodine-based polymerization control agent are charged into the reactor, a radical polymerization initiator is added, and polymerization is carried out by heating as needed to obtain the target polymer (P). The method of charging each raw material may be a batch-type initial batch charging in which all raw materials are charged at once, a semi-continuous charging in which at least some of the raw materials are continuously supplied into the reactor, or a continuous polymerization method in which all raw materials are continuously supplied and the product is continuously withdrawn from the reactor at the same time. In the continuous polymerization method, a tubular type, a tower type, a continuous stirring tank type (CSTR), or a combination thereof may be used. Of these, the tubular type and the tower type are preferred in that they can narrow the molecular weight distribution of the resulting vinyl polymer.

[0045] When polymerization is carried out in a polymerization solvent, the polymerization solvent used is preferably an organic solvent capable of dissolving monomers. Examples of organic solvents used for polymerization include aromatic compounds such as benzene, toluene, xylene, and anisole; esters such as methyl acetate, propyl acetate, and butyl acetate; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and nitriles such as acetonitrile. The polymerization solvent may be used alone or in combination of two or more. When hydrophilic monomers are used in polymerization, alcohols, water, etc., can be used as the polymerization solvent. The amount of polymerization solvent used is preferably 5 to 200 parts by mass, and more preferably 10 to 100 parts by mass, per 100 parts by mass of the total amount of monomers used for polymerization. Using 100 parts by mass or less of polymerization solvent is preferable because it allows for a high polymerization rate in a short time.

[0046] In the polymerization reaction by living radical polymerization, the reaction temperature is preferably 40°C to 100°C, more preferably 45°C to 90°C, and even more preferably 50°C to 80°C. A reaction temperature of 40°C or higher is preferable because it allows the polymerization reaction to proceed smoothly, and a reaction temperature of 100°C or lower is preferable because it suppresses the thermal decomposition of iodine-based polymerization control agents and side reactions, as well as relaxing the restrictions on the polymerization initiators and solvents that can be used. The reaction time can be appropriately set depending on the monomers used, but is preferably 1 hour to 48 hours, and more preferably 2 hours to 24 hours.

[0047] The solution containing the polymer (P) obtained by the above polymerization may be used as is in the next second step. Alternatively, the polymer (P) may be isolated and / or purified from the solution containing the polymer (P) before being used in the next second step. The isolation and purification of the polymer (P) can be carried out by employing known methods as appropriate.

[0048] <Step 2> In Step 2, a carboxylate salt is used as a modifying agent, and the polymer (P) obtained in Step 1 is reacted with the carboxylate salt. Through this reaction, a modified product can be obtained in which the anionic portion of the carboxylate salt is introduced to the end of polymer (P) by utilizing the terminal halogen of polymer (P). Examples of carboxylate salts to be reacted with polymer (P) in Step 2 include compounds represented by the above general formula (1).

[0049] In the reaction between polymer (P) and carboxylate, the amount of carboxylate used is preferably 0.5 mol equivalent or more relative to the terminal halogen of polymer (P). By using an amount of carboxylate within the above range, terminal modification of polymer (P) by the carboxylate can be efficiently carried out. From this viewpoint, the amount of carboxylate used is more preferably 1.0 mol equivalent or more, and even more preferably 1.2 mol equivalent or more, relative to the terminal halogen of polymer (P). Furthermore, from the viewpoint of minimizing the amount of unreacted carboxylate remaining in the final product, the amount of carboxylate used is preferably 30 mol equivalent or less, more preferably 25 mol equivalent or less, and even more preferably 20 mol equivalent or less, relative to the terminal halogen of polymer (P).

[0050] The reaction between the polymer (P) and the carboxylate salt is preferably carried out in a solvent. Examples of solvents used in the reaction between the polymer (P) and the carboxylate salt (hereinafter also referred to as the "reaction solvent") include nitriles such as acetonitrile; esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ethers such as methyl orthoformate, trimethyl orthoacetate, anisole, tetrahydrofuran, and dioxane; aromatic hydrocarbons such as benzene, toluene, and xylene; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and the like.

[0051] From the viewpoint of rapidly advancing the reaction between the polymer (P) and the carboxylate salt and shortening the time required for polymer terminal modification, the reaction solvent is selected based on the polar component δ in the Hansen solubility parameter. ｐ 0.5 (cal / cm) ０．５ It is preferable to use the solvents described above. Here, the Hansen solubility parameter is defined as the Hildebrand solubility parameter (SP value: δ) with the dispersion force term (δ). d ), polar term (δ ｐ ) and hydrogen bonding term (δ h ) is an index that takes into account the polarity of physical properties by dividing it into three components, and is "δ ２ = (δ d ) ２ + (δ ｐ ) ２ + (δh ) ２ There is a relationship between the two. In this specification, the polar component δ in the Hansen solubility parameter of the solvent is defined as follows. ｐ This value was calculated using the method described in the document "C. M. Hansen, 'The three-dimensional solubility parameter.' Danish Technical: Copenhagen 14 (1967)."

[0052] Polar component δ in the Hansen solubility parameter of the reaction solvent ｐ This method has a high effect in shortening the time required for polymer end modification, with a value of 1.0 (cal / cm). ０．５ The above is more preferable, 1.5 (cal / cm) ０．５ The above is even more preferable, 1.8 (cal / cm) ０．５ The above is even more preferable, 2.0 (cal / cm) ０．５ The above is even more preferable, 2.5 (cal / cm) ０．５ The above is particularly preferred. The polar component δ in the Hansen solubility parameter of the reaction solvent. ｐ There is no particular upper limit; for example, 12.0 (cal / cm³) ０．５ The following applies:

[0053] The reaction solvent may be used alone or as a mixture of two or more. When a mixture of two or more reaction solvents is used, the polar component δ of the Hansen solubility parameter of the mixture solvent is also considered. ｐ The polar component δ of each solvent contained in the mixed solvent ｐ It is preferable that the summation average of the values ​​falls within the above preferred range.

[0054] In order to achieve a high introduction rate while shortening the time required for end modification when modifying vinyl polymers, it is preferable to use at least one selected from the group consisting of nitriles, esters, and ethers as the reaction solvent. Among these, at least one selected from the group consisting of nitriles, esters, and ethers, which has a polar component δ in the Hansen solubility parameter, is preferable.ｐ 1.0 (cal / cm) ０．５ The above solvents can be used particularly preferably.

[0055] The amount of reaction solvent used is preferably 5 to 800 parts by mass, and more preferably 10 to 500 parts by mass, per 100 parts by mass of polymer (P), from the viewpoint of increasing the reaction efficiency between polymer (P) and carboxylate. The reaction temperature when reacting polymer (P) and carboxylate is, for example, 20°C to 100°C, and preferably 30 to 95°C, from the viewpoint of retaining the end groups introduced into polymer (P) and suppressing discoloration of the vinyl polymer. The reaction time is, for example, 0.1 to 24 hours, and preferably 0.1 to 12 hours.

[0056] These reactions yield vinyl polymers in which substructures derived from the anionic portion of the carboxylate salt are introduced at the molecular ends. When isolating and / or purifying the vinyl polymer obtained from the reaction in the second step, known methods can be appropriately employed for these processes.

[0057] For vinyl polymers (M), the number-average molecular weight (Mn) in polystyrene terms, measured by gel permeation chromatography (GPC), is, for example, in the range of 2,000 to 1,000,000. A Mn of 2,000 or more makes it easier to express desired properties in the vinyl polymer. A Mn of 1,000,000 or less is preferable in that it ensures sufficient processability, such as coating properties, and handling. The Mn of vinyl polymers (M) is preferably 5,000 or more, and more preferably 8,000 or more. The upper limit of the Mn of vinyl polymers (M) is preferably 800,000 or less, and more preferably 600,000 or less. The preferred range for the Mn of vinyl polymers (M) can be determined by appropriately combining the upper and lower limits described above. The Mn content of the vinyl polymer is preferably 5,000 to 800,000, and more preferably 8,000 to 600,000.

[0058] The weight-average molecular weight (Mw) of the vinyl polymer (M), measured by GPC in terms of polystyrene, is, for example, in the range of 2,000 to 1,000,000. The Mw of the vinyl polymer (M) is preferably 5,000 or more, and more preferably 8,000 or more. The upper limit of the Mw of the vinyl polymer (M) is preferably 800,000 or less, and more preferably 700,000 or less. The range of Mw for the vinyl polymer (M) is preferably 5,000 to 800,000, and more preferably 8,000 to 600,000.

[0059] The molecular weight distribution (Mw / Mn) of the vinyl polymer (M) is preferably 3.0 or less, as this facilitates the expression of desired properties in the vinyl polymer (M). More preferably, the molecular weight distribution (Mw / Mn) is 2.5 or less, and even more preferably 2.0 or less. The lower limit of the molecular weight distribution (Mw / Mn) is not particularly limited, but from the viewpoint of ease of manufacture, it is, for example, 1.01 or more.

[0060] The vinyl polymer (M) of this disclosure can be used in a wide range of applications. Specifically, it can be applied to various uses such as sealants, adhesives, sealants, paints, dispersants, industrial rubbers, binders, and coatings. Application fields include civil engineering and construction materials, automotive parts, home appliance and office automation equipment parts, medical equipment parts, packaging materials, daily necessities, electric wires, and general merchandise.

[0061] Curable Resin Composition and Cured Product The curable resin composition of this disclosure contains the vinyl polymer (M) described above. Such a curable resin composition of this disclosure is useful as a curable resin composition for producing cured products in the various fields described above by utilizing the (meth)acryloyloxy groups at the molecular ends of the vinyl polymer (M) as crosslinkable functional groups. In particular, a curable resin composition containing the vinyl polymer (M) can be used to obtain a cured product with excellent color resistance and transparency.

[0062] The curable resin composition of this disclosure may optionally contain a vinyl polymer (M) along with components other than the vinyl polymer (M) (other components). Known components used in curable resin compositions for various applications can be appropriately used as the other components. Specific examples of other components include, for example, thermal or photopolymerization initiators, crosslinking agents, curing accelerators, other polymers, plasticizers, fillers, pigments, adhesion promoters, dehydrating agents, antioxidants, UV absorbers, oils, solvents, etc. The amounts of these components can be appropriately set according to each component.

[0063] In the curable resin composition of this disclosure, the content of the vinyl polymer (M) can be appropriately set depending on the application. Specifically, the content of the vinyl polymer (M) may be 0.1 to 100% by mass or 1 to 99% by mass, based on the total amount of components other than the solvent contained in the curable resin composition. For example, when the vinyl polymer (M) is used as the main component, the content of the vinyl polymer (M) may be 50% by mass or more or 70% by mass or more, based on the total amount of components other than the solvent contained in the curable resin composition. Also, when a small amount of the vinyl polymer (M) is used, the content of the vinyl polymer (M) may be 0.1 to 20% by mass or 1 to 10% by mass, based on the total amount of components other than the solvent contained in the curable resin composition. When the curable resin composition of this disclosure is solvent-type, the solid content concentration of the curable resin composition of this disclosure may be, for example, 1 to 95% by mass or 2 to 90% by mass.

[0064] The method for obtaining a cured product using the curable resin composition of this disclosure is not particularly limited, and known curing methods can be used as appropriate. A preferred embodiment of the curable resin composition of this disclosure is a resin composition that cures by heat or light. From the viewpoint of ensuring that the curing reaction utilizing the (meth)acryloyloxy groups at the molecular ends proceeds sufficiently, the curable composition of this disclosure may be a resin composition containing a thermal or photopolymerization initiator and / or a crosslinking agent. Known compounds that are incorporated into thermal or photopolymerization resin compositions can be used as the thermal or photopolymerization initiator and crosslinking agent as appropriate.

[0065] When a thermal or photopolymerization initiator is incorporated into the curable resin composition of this disclosure, the content of the thermal or photopolymerization initiator may be, for example, 0.1 to 30 parts by mass, or 0.2 to 20 parts by mass, based on 100 parts by mass of the total amount of vinyl polymer (M) contained in the curable resin composition of this disclosure. Furthermore, when a crosslinking agent is incorporated, the content of the crosslinking agent may be, for example, 0.1 to 30 parts by mass, or 0.2 to 20 parts by mass, based on 100 parts by mass of the total amount of vinyl polymer (M) contained in the curable resin composition of this disclosure.

[0066] The present invention will be described in detail below based on the following examples. However, the present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass," respectively, unless otherwise specified.

[0067] The measurement and evaluation methods for each property of vinyl polymers are shown below. (1) Molecular weight measurement For the vinyl polymers obtained in each example and comparative example, gel permeation chromatography (GPC) was performed under the conditions described below to obtain the number-average molecular weight (Mn) and weight-average molecular weight (Mw) in polystyrene equivalent. The molecular weight distribution (Mw / Mn) was also calculated from the obtained values. ○ Measurement conditions Column: TSKgel SuperMultiporeHZ-M manufactured by Tosoh × 4 Solvent: Tetrahydrofuran Temperature: 40℃ Detector: RI Flow rate: 600 μL / min

[0068] (2) Average number of acryloyl groups in vinyl polymers For vinyl polymers obtained in each example and comparative example, １ The average number of acryloyl groups was calculated using the following formula based on the integral values ​​measured by 1H-NMR spectroscopy and the number-average molecular weight (Mn) obtained from GPC measurements: Average number of acryloyl groups in vinyl polymers = (number-average molecular weight) / [(integral value derived from constituent monomers) / (integral value derived from acryloyl groups) × (molecular weight of constituent monomers)]

[0069] (3) Acrylate content in vinyl polymers For the vinyl polymers obtained in each example and comparative example, １The acrylate content was calculated from the integrated values ​​measured by 1H-NMR spectroscopy using the following formula: Acrylate content in vinyl polymer = [(Integral value from acrylate) × (Molecular weight of acrylate)] / [(Integral value from constituent monomer) × (Molecular weight of constituent monomer)]

[0070] [Synthesis Example 1 (Synthesis of 1,4-bis(iodomethyl)benzene (Bz-II))] Under a nitrogen atmosphere, p-xylene-α,α'-diol (62.5 mmol, 8.64 g) and NaI (250 mmol, 37.5 g) were added and dissolved in anhydrous acetonitrile (500 mL). BF was added at room temperature. ３ The ether complex (250 mmol, 30.8 mL) was slowly added dropwise. After the addition was complete, the mixture was allowed to react at room temperature for 30 minutes. The reaction mixture was poured into ice water (250 g) and stirred, and 20% sodium thiosulfate (250 mL) was added and the mixture was transferred to a separatory funnel. The mixture was extracted with toluene (3 × 500 mL), and the organic layer was washed in the order of distilled water (2 × 200 mL) and saturated brine (200 mL). The mixture was dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated using a rotary evaporator. The resulting crude product was purified by column chromatography.

[0071] [Synthesis Example 2 (Synthesis of Tetrabutylammonium Acrylate (hereinafter also referred to as "TBAA"))] Acrylic acid (22.98 g) was added dropwise to a 40% methanol solution of tetrabutylammonium hydroxide (206 g) and stirred at room temperature for 2 hours. The reaction mixture was dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated using a rotary evaporator. The concentrated solution was vacuum-dried to obtain a white solid of TBAA.

[0072] ≪Production and Evaluation of Vinyl Polymers and Curable Resin Compositions≫ [Production Example 1 (Production of Modified Form 1)] Bz-II (11.93 g), 2,2'-azobis-2-methylbutyronitrile (hereinafter also referred to as "ABN-E") (0.24 g), n-butyl acrylate (500 g), and anisole (47.3 g) were charged into a 1 L flask equipped with a stirrer and thermometer. The flask was thoroughly degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 70°C. After 4 hours, the reaction was stopped by cooling to room temperature. The obtained solution was reprecipitated and purified using methanol, and then polymer P1 was obtained by vacuum drying. The molecular weight of the obtained polymer P1 was Mn 14,000, Mw 21,100, and Mw / Mn 1.51, as measured by GPC (gel permeation chromatography) (polystyrene equivalent). Next, polymer P1 (100 g) and acetonitrile (66.7 g) were placed in a 1 L flask equipped with a stirrer and thermometer, and polymer P1 was dissolved. After dissolving polymer P1, TBAA was added to the flask containing the polymer P1 solution, and the mixture was heated in a 70°C constant temperature bath for 3 hours. The resulting solution was reprecipitated and purified using methanol, and then vacuum dried to obtain a vinyl polymer (hereinafter also referred to as "modified polymer 1"). The molecular weight of modified polymer 1 was Mn 15,500, Mw 21,300, and Mw / Mn 1.37. The average number of acryloyl groups at the molecular ends of modified polymer 1 was 2.0, and the acrylate content was 0% by mass.

[0073] [Examples 1-4 and Comparative Example 1] As shown in Table 1, modified material 1 and TBAA were thoroughly mixed to obtain polymers 2-5. In Example 1, TBAA was not added to modified material 1, and modified material 1 was used as is as a vinyl polymer. Hereinafter, modified material 1 will be referred to as polymer 1. The transition metal atom content of polymers 1-5 was 0 ppm.

[0074] Next, as shown in Table 1, a vinyl polymer, Omnirad 184 (1-hydroxycyclohexyl phenyl ketone: manufactured by iGM REGINS), and n-butyl acetate were thoroughly mixed to obtain a curable resin composition. Cosmoshine A-4300 (trade name, easy-adhesion PET film manufactured by Toyobo Co., Ltd., film thickness: 50 μm) was prepared as the base film, and the curable resin composition was applied to the surface of the base film using bar coater #18 so that the film thickness after drying was 20 μm. Next, the curable resin composition on the surface of the base film was dried at 90°C for 60 minutes using a forced-air dryer, and then a conveyor-type ultraviolet irradiation device manufactured by iGraphics (160 W / cm metal halide lamp, integrated light intensity 1,000 mJ / cm) was used. ２ Using the measurement values ​​of a Heraeus UV POWER PUCK, four passes of irradiation were performed to obtain cured products 1 to 5. The following evaluations were performed on the obtained cured products 1 to 5.

[0075] <Color Resistance of Cured Products> The degree of yellowing (YI) of each cured product was measured using a spectrochromator and haze meter (Nippon Denshoku Co., Ltd. "COH7700" (model name)). Subsequently, the cured products were heat-treated in a forced-air dryer at 90°C for 24 hours, and the YI was measured again. The color resistance of each cured product was evaluated using the following criteria, based on ΔYI, which is obtained by subtracting the YI before heat treatment from the YI after heat treatment. The results are shown in Table 1. ◎: Less than 0.1 〇: Less than 0.5, 0.1 or more △: Less than 1.5, 0.5 or more ×: 1.5 or more

[0076] <Transparency of Cured Products> The haze value of each cured product was measured using a spectrochromator and haze meter (Nippon Denshoku Co., Ltd. "COH7700" (model name)). The transparency of each cured product was evaluated from the obtained haze values ​​using the following criteria. The results are shown in Table 1. ◎: Less than 2.0% ○: Less than 3.5%, 2.0% or more △: Less than 5.0%, 3.5% or more ×: 5.0% or more

[0077]

[0078] <<Evaluation Results>> As is clear from the results of Examples 1 to 4, the cured products formed using polymers 1 to 4, in which the acrylate content in the vinyl polymer was 7% by mass or less, exhibited excellent color resistance and transparency. In contrast, the cured product formed using polymer 5, in which the acrylate content in the vinyl polymer was more than 7% by mass (Comparative Example 1), exhibited poor color resistance and transparency.

[0079] The present invention is not limited to the embodiments described above, and encompasses various modifications and variations within the scope of equivalents, without departing from the spirit of the invention. Therefore, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of these elements, should be understood to fall within the scope and conceptual range of the present invention in light of the above teachings.

Claims

1. A vinyl polymer having a (meth)acryloyloxy group at the molecular terminus and containing 7% by mass or less of (meth)acrylate salt.

2. The vinyl polymer according to claim 1, which is a (meth)acrylic polymer.

3. A curable resin composition containing the vinyl polymer described in claim 1 or 2.

4. A cured product formed from the curable resin composition described in claim 3.

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