Polymerization initiator mixture, polymerizable composition and cured product

Abstract

The objective is to provide a polymerization initiator mixture that, when incorporated into a polymerizable composition containing a radical polymerizable compound, yields a cured film with excellent curability under LED lamps and low coloration. [Solution] (a) A polymerization initiator mixture containing a photopolymerization initiator represented by the following formula (1) and a sensitizer, wherein the sensitizer is a compound having a thioxanthone skeleton, The polymerization initiator mixture is characterized in that the content of the sensitizer is 1% by mass or more and less than 30% by mass, based on 100% by mass of the polymerization initiator mixture (a). [Formula 1] JPEG2026121013000010.jpg3064

Description

[Technical Field]

[0001] This invention relates to polymerization initiator mixtures, polymerizable compositions, and cured products. [Background technology]

[0002] Radical polymerization initiators, which generate radicals through heat, light, or oxidation-reduction reactions, are widely used as polymerization initiators for synthesizing polymers and other materials. In particular, photopolymerization initiators can generate radicals through bond cleavage or hydrogen abstraction reactions by absorbing active energy rays such as light, and are used as polymerization initiators for radical polymerizable compounds. For example, α-hydroxyacetophenone derivatives, α-aminoacetophenone derivatives, acylphosphine oxide derivatives, halomethyltriazine derivatives, benzyl ketal derivatives, and thioxanthone derivatives are used.

[0003] The photopolymerization initiators described above rapidly cure radical polymerizable compounds upon light irradiation. Therefore, from the viewpoint of rapid curing and low VOC content, they are applied to curing coatings, paints, printing inks, photosensitive printing plates, adhesives, and various photoresists.

[0004] Among the above applications, in the fields of coatings, paints, printing inks, and adhesives, there is an increasing trend to use LED lamps, which utilize light-emitting diodes as the light source due to their long lifespan and excellent energy efficiency.

[0005] However, unlike conventionally used high-pressure mercury lamps and metal halide lamps, LED lamps emit light with a single wavelength (for example, a wavelength range with a central wavelength of 350-410 nm). Therefore, conventionally used photopolymerization initiators do not have corresponding absorption wavelengths, resulting in insufficient generation of radicals and poor curing performance. To address this issue, for example, Patent Document 1 proposes a polymerizable composition that can be cured with LED lamps by using a ketocoumarin compound as a photopolymerization initiator.

[0006] Furthermore, in recent years, in the field of photopolymerization technology mentioned above, there has been a demand for photopolymerization initiators due to the curing of polymerizable compositions containing a large amount of pigment. For example, in applications such as printing inks, which are typified by offset inks, highly colored inks are necessary for quality improvement. However, as the pigment content increases, the permeability of active energy rays in the polymerizable composition decreases, making it difficult to cure the ink with conventional amounts of polymerization initiators. The same applies to coatings, paints, adhesives, and various photoresists. To address these problems, curability is ensured by increasing the amount of photopolymerization initiator added or by adding sensitizers. For example, Patent Documents 2 to 5 propose polymerizable compositions with a high pigment content, and Patent Documents 6 and 7 propose polymerizable compositions that use sensitizers in combination. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2024-092674 [Patent Document 2] Japanese Patent Publication No. 2007-254694 [Patent Document 3] Japanese Patent Publication No. 2016-080728 [Patent Document 4] Japanese Patent Publication No. 2016-061939 [Patent Document 5] Japanese Patent Publication No. 2023-124822 [Patent Document 6] Japanese Patent Publication No. 2007-119685 [Patent Document 7] Japanese Patent Publication No. 2012-236885 [Overview of the project] [Problems that the invention aims to solve]

[0008] Incidentally, when using an LED lamp as a light source to ensure curability of polymerizable compositions with a high pigment content, it is necessary to increase the amount of photopolymerization initiator or add a sensitizer. However, while increasing the amount of photopolymerization initiator or adding a sensitizer increases reactivity, it also leads to the problem of strong coloration of the cured product, negatively affecting color reproducibility. Therefore, it has been difficult to achieve both low coloration and ensured curability. Specifically, the polymerizable compositions described in Patent Documents 1, 6, and 7 have the problem of coloration of the resulting cured film, and the polymerizable compositions described in Patent Documents 2 to 5 have problems with curability using an LED lamp as a light source.

[0009] The present invention aims to provide a polymerization initiator mixture that, when incorporated into a polymerizable composition containing a radical polymerizable compound, yields a cured film with excellent curability under an LED lamp and low coloration, a polymerizable composition containing the polymerization initiator mixture, and a cured product thereof. [Means for solving the problem]

[0010] In view of the above problems, the present inventors conducted diligent studies and found that the above problems can be solved by a polymerization initiator mixture containing a photopolymerization initiator represented by formula (1) and a sensitizer consisting of a specific amount of a compound having a thioxanthone skeleton, and thus completed the present invention. The present invention relates to the following [1] to [3].

[0011] [1] (a) A polymerization initiator mixture containing a photopolymerization initiator represented by the following formula (1) and a sensitizer, wherein the sensitizer is a compound having a thioxanthone skeleton. The polymerization initiator mixture is characterized in that the content of the sensitizer is 1% by mass or more and less than 30% by mass, based on 100% by mass of the polymerization initiator mixture (a). [ka] [2] A polymerizable composition comprising (a) the polymerization initiator mixture and (b) the radical polymerizable compound described in [1] above. [3] A cured product formed from the polymerizable composition described in [2] above. [Effects of the Invention]

[0012] According to the present invention, by blending into a polymerizable composition containing a radically polymerizable compound, a polymerization initiator mixture capable of obtaining a cured film excellent in curability and low in coloring in an LED lamp, a polymerizable composition containing the polymerization initiator mixture, and a cured product thereof can be provided. The photosensitizer having a thioxanthone skeleton according to the present invention functions as an optimal photosensitizer for the photopolymerization initiator represented by the formula (1). Therefore, a cured film obtained from a polymerizable composition containing a polymerization initiator mixture contained in a specific ratio has excellent curability with respect to light having a wavelength emitted from a lamp such as an LED, and coloring is suppressed.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described. In this specification, a numerical range described using the symbol "~" shall include the numerical values at both ends (lower limit and upper limit) of the symbol "~". For example, "2~5" means 2 or more and 5 or less. In this specification, (meth)acryl means acrylic and methacrylic. Further, (meth)acrylate means acrylate and methacrylate.

[0014] [Polymerization Initiator Mixture] The (a) polymerization initiator mixture of the present invention contains a photopolymerization initiator represented by the formula (1) and a photosensitizer having a thioxanthone skeleton.

[0015] [Photopolymerization Initiator] The photopolymerization initiator in the present invention can be represented by the following formula (1). [Chemical Formula]

[0016] [Production Method of Photopolymerization Initiator Represented by Formula (1)] The method for producing the photopolymerization initiator represented by formula (1) is not particularly limited, and examples include: (i) a step of synthesizing intermediate I, in which anisole is used as a starting material and the starting material and propionyl chloride are subjected to a Friedel-Crafts reaction with the action of aluminum chloride or the like to synthesize intermediate I; (ii) a step of synthesizing intermediate II, in which intermediate I and isoamyl nitrite are subsequently oxidized in the presence of a catalyst such as hydrogen chloride, sodium alkoxide, or potassium alkoxide to produce intermediate II, which is a hydroxylamine compound; and (iii) a method of synthesizing the photopolymerization initiator represented by formula (1) by subsequently esterifying intermediate II with acetyl chloride or an anhydride (acetic anhydride).

[0017] In step (i) above, for example, the starting material anisole, aluminum chloride, and organic solvent A are stirred and mixed, the temperature is cooled to 0°C, then the mixed solution of propionyl chloride and organic solution A is added dropwise, the temperature is adjusted to a range of 0 to 10°C, the mixture is added dropwise over 0.5 to 2 hours, the temperature is maintained at 0 to 30°C, and the mixture is stirred for another 0.5 to 3 hours to obtain the reaction solution. The obtained reaction solution is subjected to washing treatment, etc., to obtain a white solid intermediate I. The molar ratio of the starting material to aluminum chloride (starting material / aluminum chloride) is usually about 0.1 to 1.5, and preferably about 0.5 to 1.0. The molar ratio of the starting material to propionyl chloride (starting material / propionyl chloride) is usually about 0.1 to 1.5, and preferably about 0.5 to 1.0.

[0018] Examples of the organic solvent A include dichloroethane, dichloromethane, and carbon tetrachloride.

[0019] In step (ii), for example, a catalyst such as hydrogen chloride is added to a mixed solution of intermediate I produced in step (i), organic solvent B, and isoamyl nitrite, and the mixture is reacted at room temperature with stirring for 1 to 10 hours to obtain a reaction solution. The obtained reaction solution is subjected to washing treatment or the like to obtain intermediate II, a viscous liquid. The molar ratio of intermediate I to isoamyl nitrite (intermediate I / isoamyl nitrite) is usually about 0.2 to 0.8, and preferably about 0.4 to 0.7.

[0020] Examples of the organic solvent B include dichloroethane and tetrahydrofuran.

[0021] In step (iii), for example, the intermediate II produced in step (ii), an amine catalyst such as pyridine, and the above-mentioned organic solvent B are stirred and mixed, the temperature is cooled to 0°C, and then the solution containing acetyl chloride or anhydride and organic solvent B is added dropwise, and the mixture is added dropwise over 0.5 to 1.5 hours, followed by stirring for 1 to 4 hours to obtain a reaction solution. The obtained reaction solution is subjected to washing treatment or the like to obtain a photopolymerization initiator represented by formula (1). The molar ratio of intermediate II to acetyl chloride or anhydride (intermediate II / acetyl chloride or anhydride) is usually about 0.2 to 0.8, and preferably about 0.4 to 0.7.

[0022] <Other polymerization initiators> The polymerization initiator mixture (a) of the present invention may contain other polymerization initiators other than the photopolymerization initiator represented by formula (1) described above. By using other polymerization initiators, taking into consideration the polymerizability of the radical polymerizable compound (b) contained in the polymerizable composition, the types of light-absorbing and scattering pigments contained in the polymerizable composition, the film thickness of the cured product, etc., the surface curability, deep curability, transparency, etc. of the polymerizable composition can be improved.

[0023] Other polymerization initiators that are known can be used, for example, α-hydroxyacetophenone derivatives such as 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methylpropiophenone, 4'-(2-hydroxyethoxy)-2-hydroxy-2-methylpropiophenone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one; 2-methyl-4'-methylthio-2-morpholinopropiophenone, 2-benzyl-2-(N,N-di Alpha-aminoacetophenone derivatives such as methylamino)-1-(4-morpholinophenyl)butan-1-one and 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)butan-1-one; acylphosphine oxide derivatives such as diphenyl-2,4,6-trimethylbenzoylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and ethyl(mesitylcarbonyl)phenylphosphineate; 1-[4-(phenylthio)phenyl]octane-1,2-dione-2 -(O-benzoyl oxime), 1-[({1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethylidene}amino)oxy]ethanone, [8-[5-(2,4,6-trimethylphenyl)-11-(2-ethylhexyl)-11H-benzo[a]carbazoyl]][2-(2,2,3,3-tetrafluoropropoxy)phenyl]methanone-(O-acetyl oxime), 1-[4-[4-(2-benzofuranylcarbonyl)phenyl]thio]phenyl-4-methyl-1-pentanone-1-(O-acetyl oxime) Oxime ester derivatives such as tyloxime; halomethyltriazine derivatives such as 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(3,4-dimethoxystyryl)-4,6-bis(trichloromethyl)1,3,5-triazine, and 2-(4-ethoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine; benzyl ketal derivatives such as 2,2-dimethoxy-2-phenylacetophenone; benzophenone derivatives such as 4-(4-methylphenylthio)benzophenone;Examples include coumarin derivatives such as 3-benzoyl-7-diethylaminocoumarin and 3,3'-carbonylbis(7-diethylaminocoumarin); imidazole derivatives such as 2-(2-chlorophenyl)-1-[2-(2-chlorophenyl)-4,5-diphenyl-1,3-diazole-2-yl]-4,5-diphenylimidazole; organic peroxides such as 3,3',4,4'-tetrakis(tert-butylperoxycarbonyl)benzophenone, 2-(1-tert-butylperoxy-1-methylethyl)-9H-thioxanthene-9-one, dibenzoyl peroxide, and 2-(1-hydroperoxy-1-methylethyl)-9H-thioxanthene-9-one; azo compounds such as azobisisobutyronitrile; and camphorquinone. Among these, one or more selected from acylphosphine oxide derivatives, thioxanthone derivatives such as 2-isopropyl-9H-thioxanthene-9-one and 2-(2-hydroxypropan-2-yl)-9H-thioxan-9-one, and 1-(4-methoxyphenyl)-1,2-propanedione are preferred. Other polymerization initiators may be used alone or in combination of two or more.

[0024] When the polymerization initiator mixture (a) contains the other polymerization initiator, the proportion of the other polymerization initiator can be appropriately set according to the wavelength emitted from the lamp, etc., but examples include 50% by mass or less and 30% by mass or less in the polymerization initiator mixture (a).

[0025] <Sensitizer> The photopolymerization initiator represented by formula (1) of the present invention, when used in combination with a compound having a thioxanthone skeleton, exhibits excellent curability to light of wavelengths emitted from lamps such as LEDs, and also suppresses discoloration. Sensitizers are compounds that absorb energy from exposure to active energy rays and can transfer that energy to photopolymerization initiators. In contrast, the aforementioned photopolymerization initiators are compounds that generate radicals through bond cleavage or hydrogen abstraction reactions upon exposure to active energy rays. Therefore, sensitizers and photopolymerization initiators are functionally different.

[0026] Compounds having a thioxanthone skeleton include, specifically, thioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-dodecylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3-(2-methoxyethoxycarbonyl)thioxanthone, and 4-butoxycarbonyl Luthioxanthone, 3-butoxycarbonyl-7-methylthioxanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfurylthioxanthone, 3,4-di[2-(2-methoxyethoxy)ethoxycarbonyl]thioxanthone, 1-ethoxycarbonyl-3-(1-methyl (1,1,1-)methyl-1-morpholinoethyl)thioxanthone, 2-methyl-6-dimethoxymethylthioxanthone, 2-methyl-6-(1,1-dimethoxybenzyl)thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, n-allylthioxanthone-3,4-dicarboximide, n-octylthioxanthone-3,4-dicarboximide, N-(1,1,3,3-tetramethylbutyl)thioxanthone-3,4-dicarboximide, 1 Examples include phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-polyethylene glycol ester, and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthone-2-yloxy)-N,N,N-trimethyl-1-propaneaminium chloride, and polybutylene glycol-bis-(9-oxo-9H-thioxanthenyloxy)-acetate. Among these, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, and polybutylene glycol-bis-(9-oxo-9H-thioxanthenyloxy)-acetate are preferred from the viewpoint of curability.

[0027] Compounds having a thioxanthone skeleton may be commercially available. Examples of commercially available products include SPEEDCURE 7010, SPEEDCURE CPTX, and SPEEDCURE ITX from Lambson, Genopol TX-1 and Genopol TX-2 from Rahn AG, and Omnipol TX from iGM.

[0028] From the viewpoint of suppressing discoloration of the cured film, the content of the sensitizer is less than 30% by mass, and more preferably 25% by mass or less, relative to 100% by mass of the polymerization initiator mixture. Furthermore, from the viewpoint of efficiently absorbing light emitted from lamps such as LED lamps and efficiently generating radicals, the content is 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 20% by mass or more.

[0029] The total amount of the photopolymerization initiator represented by formula (1) and the compound having a thioxanthone skeleton as a sensitizer, relative to 100% by mass of the polymerization initiator mixture (a) of the present invention, is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0030] <Polymerizable composition> The polymerizable composition of the present invention contains (a) the polymerization initiator mixture and (b) the radical polymerizable compound.

[0031] <(b) Radical polymerizable compounds> As the (b) radical polymerizable compound, compounds having an ethylenically unsaturated group can be preferably used. Examples of the (b) radical polymerizable compound include (meth)acrylic acid esters, (meth)acrylamides, (meth)acrylic acid, styrenes, maleic acid esters, fumaric acid esters, itaconic acid esters, cinnamic acid esters, crotonic acid esters, vinyl ethers, vinyl esters, vinyl ketones, allyl ethers, allyl esters, N-substituted maleimides, N-vinyl compounds, unsaturated nitriles, olefins, and the like. Among these, it is preferable to include (meth)acrylic acid esters, which have high reactivity. The (b) radical polymerizable compound may be used alone or in combination of two or more types.

[0032] The (meth)acrylic acid esters can be monofunctional or polyfunctional compounds. Examples of monofunctional compounds include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyl oxy Ester compounds of (meth)acrylic acid with alicyclic alcohols, such as ethyl (meth)acrylate and 2-ethyl-2-adamantyl (meth)acrylate; aryl (meth)acrylates, such as phenyl (meth)acrylate and benzyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-hydroxy-1-adamantyl (meth)acrylate, polyethylene glycol mono(meth)acrylate monomers having hydroxyl groups such as phosphates, polypropylene glycol mono(meth)acrylate; methoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, 2-phenylphenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate Monomers having linear or cyclic ether links, such as phosphates and cyclic trimethylolpropaneformal (meth)acrylate; monomers having nitrogen atoms, such as N,N-dimethylaminoethyl (meth)acrylate and N-(meth)acryloyloxyethyl hexahydrophthalimide; monomers having isocyanate groups, such as 2-(meth)acryloyloxyethyl isocyanate; monomers having epoxy groups, such as glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether;Examples include monomers having a phosphorus atom, such as 2-(meth)acryloyloxy)ethyl phosphate; monomers having a silicon atom, such as 3-(meth)acryloxypropyltrimethoxysilane; monomers having a fluorine atom, such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3,3-pentafluoropropyl (meth)acrylate, and 2-(perfluorohexyl)ethyl (meth)acrylate; and monomers having a carboxyl group, such as mono(2-(meth)acryloyloxyethyl) succinate, mono(2-(meth)acryloyloxyethyl) phthalate, mono(2-(meth)acryloyloxyethyl) maleate, and ω-carboxy-polycaprolactone mono(meth)acrylate.

[0033] Examples of the aforementioned polyfunctional compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, glycerin tri(meth)acrylate, glycerin propoxy tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol di(meth)acrylate monostearate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and hydroxy Neopentyl glycol di(meth)acrylate cypivalate, tricyclodecane dimethanol di(meth)acrylate, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypolyethoxyphenyl)propane, 9,9-bis(4-(2-(meth)acryloyloxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-(2-(meth)acryloyloxyethoxy)ethoxy)phenyl) Examples include ester compounds of polyhydric alcohols such as fluorene and (meth)acrylic acid; bis(4-(meth)acryloxyphenyl) sulfide, bis(4-(meth)acryloylthiophenyl) sulfide, tris(2-(meth)acryloyloxyethyl) isocyanurate, zinc (meth)acrylate, zirconium (meth)acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, epoxy acrylate, polyester acrylate, etc.

[0034] Of the (meth)acrylic acid esters, ester compounds of the polyhydric alcohol and (meth)acrylic acid are preferred from the viewpoint of improving the sensitivity of the polymerizable composition, reducing oxygen inhibition, and improving the mechanical strength, hardness, heat resistance, durability, and chemical resistance of the cured coating film. In particular, trimethylolethane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate are preferred.

[0035] From the viewpoint of curability, the content of (a) polymerization initiator mixture in the polymerizable composition is preferably 0.1 parts by mass or more, and more preferably 1.0 part by mass or more, per 100 parts by mass of the (b) radical polymerizable compound. Furthermore, from the viewpoint of solubility in the (b) radical polymerizable compound and suppressing discoloration of the cured film, the content of (a) polymerization initiator mixture is preferably 40 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of the (b) radical polymerizable compound.

[0036] <Pigments> The polymerizable composition can be suitably used as a coating agent, paint, printing ink, photosensitive printing plate, adhesive, and various photoresists such as color resists and black resists by incorporating a pigment. The pigment can be, but is not particularly limited, yellow pigment, blue pigment, red pigment, white pigment, black pigment, carbon black, etc., which are commonly used in applications such as coating agents, paints, printing inks, photosensitive printing plates, adhesives, and various photoresists such as color resists and black resists. The pigment may be used alone or in combination of two or more types.

[0037] When using the aforementioned pigment, the proportion of the pigment is preferably about 10 to 90% by mass, and more preferably about 20 to 50% by mass, of the total solid content of the polymerizable composition. If the pigment content is too low, sufficient coloring may not be obtained, and conversely, if the pigment content is too high, it may lead to a decrease in the strength and image-forming properties of the cured film.

[0038] <Alkali-soluble resin> The polymerizable composition can be suitably used as a negative-type resist by blending it with an alkali-soluble resin. The alkali-soluble resin can be one that is commonly used for negative-type resists, and is not particularly limited as long as it is soluble in an alkaline aqueous solution, but it is preferably a resin containing a carboxyl group. The alkali-soluble resin may be used alone or in combination of two or more types.

[0039] For example, the alkali-soluble resin preferably used is a carboxyl group-containing (meth)acrylic acid ester copolymer or a carboxyl group-containing epoxy acrylate resin.

[0040] The carboxyl group-containing (meth)acrylic acid ester copolymer is a copolymer comprising at least one selected from the monofunctional compounds of the aforementioned (meth)acrylic acid esters (excluding the monomer having the carboxyl group) and at least one selected from ethylenically unsaturated group-containing carboxylic acids such as (meth)acrylic acid, (meth)acrylic acid dimers, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinylbenzoic acid, cinnamic acid, succinic acid mono(2-(meth)acryloyloxyethyl) succinate, phthalic acid mono(2-(meth)acryloyloxyethyl) phthalate, maleic acid mono(2-(meth)acryloyloxyethyl), ω-carboxy-polycaprolactone mono(meth)acrylate, and their acid anhydrides.

[0041] Examples of the carboxyl group-containing (meth)acrylic acid ester copolymer include copolymers of methyl methacrylate, cyclohexyl methacrylate, and methacrylic acid. Furthermore, styrene, α-methylstyrene, N-vinyl-2-pyrrolidone, N-methylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, diethyl fumarate, diethyl itaconate, etc., may also be copolymerized.

[0042] Furthermore, in order to achieve both the developability of the negative resist and the film properties such as heat resistance, hardness, and chemical resistance, carboxyl group-containing (meth)acrylic acid ester copolymers in which reactive groups such as ethylenically unsaturated groups are introduced into the side chains are also preferably used. As methods for introducing ethylenically unsaturated groups into the side chains, for example, a method of adding a compound having an epoxy group and an ethylenically unsaturated group in the molecule, such as glycidyl (meth)acrylate, to a part of the carboxyl group of the carboxyl group-containing (meth)acrylic acid ester copolymer; a method of adding an ethylenically unsaturated group-containing monocarboxylic acid such as methacrylic acid to an epoxy group and carboxyl group-containing (meth)acrylic acid ester copolymer; or a method of adding a compound having an isocyanate group and an ethylenically unsaturated group in the molecule, such as 2-(meth)acryloyloxyethyl isocyanate, to a hydroxyl group and carboxyl group-containing (meth)acrylic acid ester copolymer.

[0043] As the carboxyl group-containing epoxy acrylate resin, a compound obtained by further reacting an acid anhydride with an epoxy acrylate resin, which is a reaction product of an epoxy resin and an ethylenically unsaturated group-containing carboxylic acid, is preferred.

[0044] Examples of the epoxy resins include (o,m,p-)cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, trisphenolmethane type epoxy resin, and bisphenylfluorene type epoxy resin. The epoxy resin may be used alone or in combination of two or more types.

[0045] Examples of the aforementioned acid anhydrides include maleic anhydride, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, chloreindoic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, and itaconic anhydride.

[0046] Furthermore, during the synthesis of carboxyl group-containing epoxy acrylate resins, the number of carboxyl groups can be increased by hydrolyzing the acid anhydride groups remaining after the reaction using tricarboxylic acid anhydrides such as trimellitic anhydride, as needed. Additionally, the number of ethylenically unsaturated double bonds can be further increased by using maleic anhydride containing ethylenically unsaturated groups.

[0047] The acid value of the alkali-soluble resin is preferably 20 to 300 mg KOH / g, and more preferably 40 to 180 mg KOH. If the acid value is less than 20 mg KOH / g, it is undesirable because the solubility in the alkaline aqueous solution is poor, making it difficult to develop the unexposed areas. Also, if the acid value is more than 300 mg KOH / g, it is undesirable because the exposed areas tend to detach easily from the substrate during development.

[0048] The weight-average molecular weight of the alkali-soluble resin is preferably 1,000 to 100,000, and more preferably 1,500 to 30,000. If the weight-average molecular weight is less than 1,000, the heat resistance and hardness of the exposed area are poor, which is undesirable. If the weight-average molecular weight is greater than 100,000, development of the unexposed area may be difficult, which is also undesirable. The weight-average molecular weight can be measured by gel permeation chromatography (GPC). As an example, the weight-average molecular weight can be determined as polystyrene equivalent by performing chromatography under the following conditions: using an HLC-8220GPC (manufactured by Tosoh Corporation) as the GPC instrument, three TSKgelHZM-M (manufactured by Tosoh Corporation) as the columns, with tetrahydrofuran as the developing solvent, a column temperature of 40°C, a flow rate of 0.3 ml / min, an RI detector, a sample injection concentration of 0.5 mass%, and an injection volume of 10 microliters.

[0049] Furthermore, the proportion of the alkali-soluble resin is preferably 10 to 70% by mass, and more preferably 15 to 60% by mass, of the total solid content of the polymerizable composition. If the proportion is less than 10% by mass, it is undesirable because the developability is poor. If the proportion is more than 70% by mass, it is undesirable because the reproducibility of the pattern shape and heat resistance are reduced.

[0050] Furthermore, the alkali-soluble resin can be obtained by isolating and purifying the alkali-soluble resin, which is the active ingredient, after the synthesis reaction. Alternatively, the reaction solution obtained from the synthesis reaction, its dried product, etc., can be used as is.

[0051] Other components that can be added to the polymerizable composition include additives commonly used in applications such as coatings, paints, printing inks, photosensitive printing plates, adhesives, and various photoresists such as color resists and black resists. Examples of additives include sensitizers other than the thioxanthone compounds mentioned above (benzophenone derivatives such as 4,4'-bis(diethylamino)benzophenone; anthracene derivatives such as 9,10-dibutoxyanthracene; coumarin derivatives such as coumarin and ketocoumarin; acridine derivatives such as acridine orange and 9-phenylacridine; benzoic acid ester derivatives such as ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, and (2-dimethylamino)ethyl benzoate; alkylamine derivatives such as triethanolamine and methyldiethanolamine; camphorquinone, etc.), polymerization inhibitors (p-methoxyphenol, hydroquinone, 2,6-di-t-butyl-4-methylphenol, pheno Examples of additives include ultraviolet absorbers (such as thiazine), infrared absorbers, light stabilizers, antioxidants, leveling agents, surface modifiers, surfactants, thickeners, defoamers, adhesion promoters, plasticizers, epoxy compounds, thiol compounds, resins having ethylenically unsaturated bonds, saturated resins, coloring dyes, fluorescent dyes, pigments (organic pigments, inorganic pigments), carbon-based materials (carbon fibers, carbon black, graphite, graphitized carbon black, activated carbon, carbon nanotubes, fullerenes, graphene, carbon microcoils, carbon nanohorns, carbon aerogels, etc.), metal oxides (titanium oxide, iridium oxide, zinc oxide, alumina, silica, etc.), metals (silver, copper, etc.), inorganic compounds (glass powder, layered clay minerals, mica, talc, calcium carbonate, etc.), dispersants, flame retardants, etc. Additives may be used individually or in combination of two or more types.

[0052] The content of the additive is selected appropriately depending on the intended use and is not particularly limited, but is generally preferably 500 parts by mass or less, and more preferably 100 parts by mass or less, per 100 parts by mass of the radical polymerizable compound (b).

[0053] The polymerizable composition may also contain a solvent to improve viscosity, paintability, and the smoothness of the cured film. The solvent is not particularly limited as long as it can dissolve or disperse the components such as (a) the polymerization initiator mixture and (b) the radical polymerizable compound, and is volatile at the drying temperature.

[0054] Examples of the aforementioned solvents include water, alcohol-based solvents, carbitol-based solvents, ester-based solvents, ketone-based solvents, ether-based solvents, lactone-based solvents, unsaturated hydrocarbon-based solvents, cellosolve acetate-based solvents, carbitol acetate-based solvents, propylene glycol monomethyl ether acetate, and diethylene glycol dimethyl ether. The solvent may be used alone or in combination of two or more types.

[0055] The amount of solvent used is preferably 10 to 1000 parts by mass, and more preferably 20 to 500 parts by mass, per 100 parts by mass of the solid content of the polymerizable composition.

[0056] <Method for preparing polymerizable compositions> When preparing the polymerizable composition, the components (a) polymerization initiator mixture, (b) radical polymerizable compound, and optionally the pigment may be placed in a storage container and dissolved or dispersed according to conventional methods using a paint shaker, bead mill, sand grind mill, ball mill, attritor mill, two-roll mill, three-roll mill, etc. Alternatively, the mixture may be filtered through a mesh or membrane filter, if necessary.

[0057] In the preparation of the polymerizable composition, the polymerization initiator mixture (a) may be added to the radical polymerizable composition (b) from the beginning. However, if the polymerizable composition is to be stored for a relatively long period of time, it is preferable to dissolve or disperse the polymerization initiator mixture (a) in the composition containing the radical polymerizable compound (b) immediately before use.

[0058] <Method for manufacturing hardened products> The cured product of the present invention is formed from the polymerizable composition. The method for producing the cured product is a method that includes either a step of applying the polymerizable composition onto a substrate, irradiating the polymerizable composition with active energy rays, or a step of heating the polymerizable composition.

[0059] Examples of the coating methods include spin coating, bar coating, spray coating, dip coating, flow coating, slit coating, doctor blade coating, gravure coating, screen printing, offset printing, inkjet printing, and dispenser printing. The substrate can be, for example, a film or sheet of glass, silicon wafer, metal, or plastic, or a molded product in a three-dimensional shape, and the shape of the substrate is not limited.

[0060] The process of irradiating the polymerizable composition with active energy rays involves decomposing the polymerization initiator mixture by irradiation with active energy rays such as electron beams, ultraviolet rays, visible light, and radiation, thereby polymerizing the polymerizable compound and obtaining a cured product.

[0061] The active energy rays are preferably light with a wavelength of 250 to 450 nm, and more preferably light with a wavelength of 350 to 410 nm from the viewpoint of enabling rapid curing.

[0062] As the light source for the irradiation of the aforementioned light, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, ultraviolet electrodeless lamps, LED lamps, xenon arc lamps, carbon arc lamps, sunlight, solid-state lasers such as YAG lasers, semiconductor lasers, gas lasers such as argon lasers, etc. (a) When using visible light to infrared light, which has low absorption by the polymerization initiator mixture, curing can be performed by using a sensitizer that absorbs that light as the additive.

[0063] The exposure dose of the active energy rays should be appropriately set according to the wavelength and intensity of the active energy rays and the composition of the polymerizable composition. As an example, the exposure dose in the UV-A region should be 10 to 5,000 mJ / cm². 2 Preferably, the concentration is 30-1,000 mJ / cm². 2 It is preferable that it be so.

[0064] Furthermore, if the polymerization composition contains the solvent, the method for producing the cured product may include a drying step. In particular, when applying a step of irradiating with the active energy ray after coating the polymerizable composition onto a substrate, it is preferable to provide a drying step before the step of irradiating with the active energy ray.

[0065] In the drying process, methods for drying the solvent include, for example, heat drying, forced-air heat drying, and reduced-pressure drying. There are no particular limitations on the method of heat drying, but examples include ovens, hot plates, infrared irradiation, and electromagnetic wave irradiation. Examples of forced-air heat drying methods include forced-air drying ovens.

[0066] The dry film thickness (cured film thickness) of the polymerizable composition is set appropriately depending on the application, but is preferably 0.05 to 300 μm, and more preferably 0.1 to 100 μm.

[0067] <Pattern Formation Method> When the polymerizable composition contains the alkali-soluble resin, a pattern can be formed by photolithography. The polymerizable composition is applied to a substrate in the same manner as described above, and if necessary, dried to form a dried film. Then, by irradiating the dried film with active energy rays through a mask, the radical polymerizable compound polymerizes in the exposed areas, forming a cured film. Alternatively, a highly accurate pattern shape can be created without a mask by direct drawing using a laser.

[0068] After the exposure described above, the unexposed areas are developed and removed using an alkaline developer, such as a 0.3-3% by mass aqueous sodium carbonate solution, to obtain a patterned cured film. Furthermore, to improve the adhesion between the cured film and the substrate, a post-bake is performed at 180-250°C for 20-90 minutes as a post-drying step. In this way, the desired pattern based on the cured film is formed.

[0069] The polymerizable compositions of the present invention are paints and coatings such as hard coats, coatings for optical discs, coatings for optical fibers, paints for mobile devices, paints for home appliances, paints for cosmetic containers, anti-reflective coatings for internal surfaces of optical elements, high and low refractive index coatings, heat-shielding coatings, heat-dissipating coatings, and anti-fogging agents; printing inks such as offset printing inks, gravure printing inks, screen printing inks, inkjet printing inks, conductive inks, insulating inks, and inks for light guide plates; photosensitive printing plates; nanoimprint materials; resins for 3D printers; holographic recording materials; dental materials; waveguide materials; black stripes for lens sheets; and capacitors. It can be used in a variety of applications, including green sheets and electrode materials; adhesives and sealants for FPDs, HDDs, optical pickups, image sensors, organic EL sealants, touch panel OCA, touch panel OCR, etc.; FPD resists such as color resists, black resists, protective films for color filters, photospacers, black column spacers, frame resists, TFT wiring photoresists, and interlayer insulating films; printed circuit board resists such as liquid solder resists and dry film resists; and semiconductor materials such as semiconductor resists and buffer coat films. There are no particular restrictions on its use. [Examples]

[0070] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0071] <Synthesis of photopolymerization initiator represented by formula (1)> [Synthesis Example 1-(i): Synthesis of Intermediate I (Compound 1-(i))] [ka] 0.11 mol of propionyl chloride, 0.11 mol of AlCl3, and 45 mL of dichloroethane were added to a 200 mL four-necked flask and stirred. The mixture was then cooled in an ice bath until the temperature dropped to 0°C. 0.11 mol of anisole was then added over approximately 10 minutes, while maintaining the temperature below 0°C. The mixture was kept at 0°C and stirred for 30 minutes. The reaction mixture was then gradually added to 10% hydrochloric acid water at 0°C. The lower layer was separated using a separatory funnel, and the upper layer was extracted with 50 mL of dichloroethane. The extract and the lower layer were then combined. The mixture was then washed with 5% sodium bicarbonate aqueous solution, and further washed three times with 200 mL of water until the pH was neutral. After drying with 3 g of anhydrous magnesium sulfate to remove moisture, the dichloroethane was evaporated by rotary evaporation. After evaporation was complete, the crude product in the rotating evaporator was purified with ethyl acetate and hexane to obtain compound 1-(i) (yield: 17.2 g, LC purity: 98.9%, yield: 91.6%).

[0072] [Synthesis Example 1-(ii): Synthesis of Intermediate II (Compound 1-(ii))] [ka] 0.018 mol of compound 1-(i), 10 mL of tetrahydrofuran (THF), 0.6 g of concentrated hydrochloric acid, and 0.028 mol of isoamyl nitrite were added to a 50 mL round-bottom flask and stirred at room temperature for 3 hours. The reaction mixture was then transferred to a beaker, washed three times with ethyl acetate and 10% saline solution, and separated into layers using a separatory funnel. After adding 5 g of anhydrous magnesium sulfate and drying, the mixture was filtered by suction, and the filtrate was further evaporated by rotary evaporation. After evaporation, the crude product in the rotary evaporator was purified with ethyl acetate and hexane to obtain compound 1-(ii) (yield: 1.7 g, LC purity: 96.6%, yield: 48.0%).

[0073] [Synthesis Example 1-(iii): Synthesis of Compound 1] [ka] 0.005 ml of compound 1-(ii), 1 mL of tetrahydrofuran (THF), and 0.1 g of pyridine (Py) were placed in a 20 mL round-bottom flask and stirred. 0.009 ml of acetyl chloride was then added dropwise over approximately 5 minutes. After stirring for 3 hours, 5 mL of ethyl acetate and 5 mL of 5% hydrochloric acid solution were added, and the mixture was separated using a separatory funnel. Subsequently, the mixture was washed once with 5 mL of 3% sodium bicarbonate aqueous solution, followed by washing with 5 mL of 10% saline solution. The mixture was then dried over 3 g of anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation to obtain a viscous liquid. An appropriate amount of ethyl acetate and hexane were added to the viscous liquid, and the mixture was filtered and dried to obtain compound 1 (yield: 0.059 g, LC purity: 92.5%, yield: 45.7%). 1 Table 1 shows the results of the analysis using 1H-NMR.

[0074] [Synthesis Example 2: Synthesis of Compound 2] Compound 2 of the present invention was synthesized in accordance with the method described in Synthesis Example 1, except that the starting material anisole described in Synthesis Example 1 was replaced with benzene. 1 Table 1 shows the results of the analysis using 1H-NMR. [ka]

[0075] [Table 1]

[0076] [Examples 1-5, Comparative Examples 1-4] <Preparation of polymerizable compositions> The radical polymerizable compounds, photopolymerization initiators, sensitizers, and solvents shown in Table 2 were added and thoroughly stirred to prepare the polymerizable compositions of Examples 1-5 and Comparative Examples 1-4. The amounts (parts by mass) of each component in the polymerizable compositions are as shown in Table 2.

[0077] <Evaluation of curing properties> The prepared polymerizable composition was applied onto a PET film (Cosmo Shine A4300, manufactured by Toyobo Co., Ltd.) subjected to an easy adhesion treatment using a bar coater (#18), and the solvent was dried by drying treatment in a clean oven at 90 °C for 2 minutes to produce a uniform coating film with a thickness of about 10 μm. Next, using an LED lamp with a wavelength of 385 nm (UniJet E110III, manufactured by Ushio Electric Inc.), light irradiation was performed at an illuminance of 1.3 W / cm 2 , at a line speed of 6 m / min. The cured film was palpated to evaluate whether it was tack-free. The results are shown in Table 2. ◎: The cured film becomes tack-free after one light irradiation. v 〇: The cured film becomes tack-free after two light irradiations. △: The cured film becomes tack-free after three light irradiations. ×: The cured film becomes tack-free after four or more light irradiations.

[0078] <Evaluation of colorability> The cured film obtained in the above curability evaluation was used to measure the L * , a * * , b * values of the colorimetric system according to JIS-Z-8722 by the transmission method. The b * value was evaluated as an index of yellowness, and the lower the b * value, the lower the colorability was. The results are shown in Table 2. 〇: The b * value is less than 1.2. △: The b * value is 1.2 or more and less than 2.0. ×: The b * value is 2.0 or more.

[0079]

Table 2

[0080] The compounds described in Table 2 are as follows. PE4A: Pentaerythritol tetraacrylate (reagent manufactured by Sigma-Aldrich Japan K.K.) Compound 3: 1-(4-methoxyphenyl)-1,2-propanedione DETX: 2,4-Diethylthioxanthone (Reagent manufactured by Tokyo Chemical Industry Co., Ltd.) ITX: 2-Isopropylthioxanthone (Reagent manufactured by Tokyo Chemical Industry Co., Ltd.) Omnipol TX: Polybutylene glycol-bis-(9-oxo-9H-thioxanthenyloxy)-acetate (manufactured by iGM) EMK: Ethyl Michlar's ketone (reagent manufactured by Tokyo Chemical Industry Co., Ltd.)

[0081] The results in Table 2 show that the cured film obtained from the polymerizable composition containing (a) a polymerization initiator mixture, which contains a photopolymerization initiator represented by formula (1) and a sensitizer having a thioxanthone skeleton in a specific ratio, exhibits excellent curability to light of wavelengths emitted from lamps such as LEDs, and also suppresses discoloration.

Claims

1. (a) A polymerization initiator mixture containing a photopolymerization initiator represented by the following formula (1) and a sensitizer, wherein the sensitizer is a compound having a thioxanthone skeleton. The polymerization initiator mixture is characterized in that the content of the sensitizer is 1% by mass or more and less than 30% by mass, based on 100% by mass of the polymerization initiator mixture (a). 【Chemistry 1】

2. A polymerizable composition comprising (a) a polymerization initiator mixture and (b) a radical polymerizable compound according to claim 1.

3. A cured product formed from the polymerizable composition described in claim 2.

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