JP4382433B2 - Photopolymerization initiator and photocurable composition - Google Patents

Description

  The present invention relates to an aromatic sulfonium salt which is a novel compound, a photopolymerization initiator comprising the aromatic sulfonium salt, and a photocurable composition containing the photopolymerization initiator.

  Since the photocurable composition is easy to handle, it is widely used for printing plate making materials, various resists, ultraviolet curable coatings and the like.

  Conventionally, as a photocurable composition, a photocurable monomer and / or a photopolymerizable polymer and a composition of an aryldiazonium salt (Patent Document 1), a photocurable initiator added with a photopolymerization initiator such as a triarylsulfonium complex salt, etc. A composition (Patent Document 2) and the like are known.

  However, when photopolymerization initiators such as these aryldiazonium salts and triarylsulfonium complex salts are used, the maximum absorption wavelength is 300 nm or less, so that curing occurs under conditions using a light source of 300 to 400 nm in the near ultraviolet region. There is a problem that the speed decreases. Therefore, there is a need for a novel photopolymerization initiator that has high sensitivity in the near-ultraviolet region and increases the curing speed.

US Pat. No. 3,205,157 US Pat. No. 4,231,951

  An object of the present invention is to provide a photopolymerization initiator having a large molecular extinction coefficient in the near ultraviolet region of 300 to 400 nm and increasing the curing speed, and a photocurable composition containing the photopolymerization initiator.

  The present invention provides the following general formula (1);

（式中、Ｒ^１、Ｒ^２およびＲ^３は、それぞれ独立して、水素原子、ハロゲン原子、水酸基、シアノ基、炭素数１〜１０のアルキル基、炭素数１〜４のアルコキシ基またはアシル基を、Ｘ⁻は無機酸イオンまたは有機酸イオンを示す。）

Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a cyano group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an acyl group. the, X ^- represents an inorganic acid ion or an organic acid ion).

And a photopolymerization initiator comprising the aromatic sulfonium salt and a photocurable composition containing the photopolymerization initiator.

  The aromatic sulfonium salt of the present invention can provide a photopolymerization initiator having high sensitivity in the near-ultraviolet region and increasing the curing speed, and a photocurable composition containing the photopolymerization initiator.

  The aromatic sulfonium salt of the present invention is a compound represented by the general formula (1).

In the general formula (1), R ¹ , R ² and R ³ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a cyano group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy having 1 to 4 carbon atoms. A group or an acyl group, and X ⁻ represents an inorganic acid ion or an organic acid ion.

  As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned, for example.

  Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, cyclohexyl group, 4- Examples thereof include a tert-butylcyclohexyl group.

  Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group, and a methoxyethoxy group.

  Examples of the acyl group include a formyl group and an acetyl group.

  Examples of inorganic acid ions include hexafluoroantimonate ion, hexafluoroarsenate ion, hexafluorophosphate ion, pentafluorohydroxoantimonate ion, tetrafluoroborate ion, tetrakis (pentafluorophenyl) borate ion, tetrakis (Trifluoromethylphenyl) borate ion, trifluoro (pentafluorophenyl) borate ion, tetrakis (difluorophenyl) borate ion, difluorobis (pentafluorophenyl) borate ion and the like.

  Examples of organic acid ions include methanesulfonic acid ions, ethanesulfonic acid ions, propanesulfonic acid ions, butanesulfonic acid ions, octanesulfonic acid ions, trifluoromethanesulfonic acid ions, benzenesulfonic acid ions, benzene-1,3- Disulfonic acid ion, p-toluenesulfonic acid ion, anthraquinone-1-sulfonic acid ion, anthraquinone-2-sulfonic acid ion, anthraquinone-1,5-disulfonic acid ion, methanecarboxylic acid ion, ethanecarboxylic acid ion, propanecarboxylic acid Ion, butanecarboxylate ion, octanecarboxylate ion, trifluoromethanecarboxylate ion, benzenecarboxylate ion, p-toluenecarboxylate ion and the like.

  Specific examples of the aromatic sulfonium salt of the present invention include bis (4-fluorophenyl) -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate, bis (4-fluorophenyl)- 5- (5′-methyl-2,2′-bithienyl) sulfonium hexafluorophosphate, bis (4-ethylphenyl) -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate, Bis (4-fluorophenyl) -5- (5'-acetyl-2,2'-bithienyl) sulfonium trifluoromethanesulfonate, bis (4-fluorophenyl) -5- (5'-methoxy-2,2'- Bithienyl) sulfonium hexafluorophosphate and the like.

  As a method for producing the aromatic sulfonium salt of the present invention, for example, a bithiophene represented by the following general formula (2) and a substituted or unsubstituted diphenyl sulfoxide are subjected to a condensation reaction in an acid solvent using a condensing agent. Thereafter, it can be produced by reacting with an alkali metal salt of a desired inorganic acid or organic acid ion.

In the general formula (2), R ¹ represents the same group as R ^{1 in the} general formula (1).

  Specific examples of bithiophenes include 2,2′-bithiophene, 5-methyl-2,2′-bithiophene, 5-acetyl-2,2′-bithiophene, 5-cyano-2,2′-bithiophene, 5- Examples include bromo-2,2′-bithiophene, 5-methoxy-2,2′-bithiophene, 5-ethoxy-2,2′-bithiophene, and the like.

  Specific examples of the substituted or unsubstituted diphenyl sulfoxides include diphenyl sulfoxide, 4,4′-dimethyldiphenyl sulfoxide, 4,4′-diethyldiphenyl sulfoxide, 4,4′-di-n-propyldiphenyl sulfoxide, 4, 4'-diisopropyldiphenyl sulfoxide, 4,4'-di-n-butyldiphenyl sulfoxide, 4,4'-diisobutyldiphenyl sulfoxide, 4,4'-di-tert-butyldiphenyl sulfoxide, 4,4'-di-n -Pentyl diphenyl sulfoxide, 4,4'-dimethoxydiphenyl sulfoxide, 4,4'-diethoxydiphenyl sulfoxide, 4,4'-di-n-propoxy diphenyl sulfoxide, 4,4'-diisopropoxy diphenyl sulfoxide, 4, 4'-di n-butoxydiphenyl sulfoxide, 4,4′-diisobutoxydiphenyl sulfoxide, 4,4′-di-tert-butoxydiphenyl sulfoxide, 4,4′-difluorodiphenyl sulfoxide, 4,4′-dichlorodiphenyl sulfoxide, 4,4 Examples include '-dibromodiphenyl sulfoxide, 4,4'-dicyanodiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dicyclohexyldiphenyl sulfoxide, and the like.

  The amount of diphenyl sulfoxide used is 1 to 5 mol, preferably 1 to 3 mol per mol of bithiophene. If the amount of diphenyl sulfoxide used is less than 1 mol, the yield may be reduced. Moreover, when the usage-amount of diphenyl sulfoxide exceeds 5 mol, there is no effect corresponding to a usage-amount and it is not economical.

  Specific examples of the acid solvent include methanesulfonic acid, ethanesulfonic acid, trifluoromethanesulfonic acid and the like.

  The amount of the acid solvent used is 5 to 50 mol, preferably 5 to 10 mol, per 1 mol of diphenyl sulfoxides. When the usage-amount of an acid solvent is less than 5 mol, there exists a possibility that a yield may fall. Moreover, when the usage-amount of an acid solvent exceeds 50 mol, there is no effect commensurate with the usage-amount and volume efficiency deteriorates and it is not economical.

  Specific examples of the condensing agent include concentrated sulfuric acid, acetic anhydride, polyphosphoric acid, diphosphorus pentoxide and the like.

  The amount of the condensing agent used is 0.3 to 10 mol, preferably 0.3 to 3 mol, per 1 mol of diphenyl sulfoxides. When the amount of the condensing agent used is less than 0.3 mol, the yield may decrease. Moreover, when the usage-amount of a condensing agent exceeds 10 mol, there is no effect corresponding to a usage-amount and it is not economical.

  The reaction temperature is 10 to 80 ° C, preferably 20 to 50 ° C. When reaction temperature is less than 10 degreeC, reaction rate may become slow and there exists a possibility that reaction may require a long time. Moreover, when reaction temperature exceeds 80 degreeC, a side reaction tends to occur and there exists a possibility that a yield and purity may fall. While the reaction time varies depending on the reaction temperature, it is generally 1 to 24 hours, preferably 2 to 5 hours.

  Specific examples of alkali metal salts of inorganic acids include sodium hexafluoroantimonate, potassium hexafluoroantimonate, sodium hexafluoroarsenate, potassium hexafluoroarsenate, sodium hexafluorophosphate, potassium hexafluorophosphate, pentafluoro Sodium hydroxoantimonate, potassium pentafluorohydroxoantimonate, sodium tetrafluoroborate, potassium tetrafluoroborate, sodium tetrakis (pentafluorophenyl) borate, tetrakis (pentafluorophenyl) potassium borate, tetrakis (trifluoromethylphenyl) ) Sodium borate, potassium tetrakis (trifluoromethylphenyl) borate, sodium trifluoro (pentafluorophenyl) borate, Lifluoro (pentafluorophenyl) potassium borate, tetrakis (difluorophenyl) sodium borate, tetrakis (difluorophenyl) potassium borate, difluorobis (pentafluorophenyl) sodium borate, difluorobis (pentafluorophenyl) potassium borate, etc. Is mentioned.

  Examples of alkali metal salts of organic acids include sodium methanesulfonate, potassium methanesulfonate, sodium ethanesulfonate, potassium ethanesulfonate, sodium propanesulfonate, potassium propanesulfonate, sodium butanesulfonate, and potassium butanesulfonate. Sodium octanesulfonate, potassium octanesulfonate, sodium trifluoromethanesulfonate, potassium trifluoromethanesulfonate, sodium benzenesulfonate, potassium benzenesulfonate, sodium benzene-1,3-disulfonate, benzene-1,3-disulfone Potassium acetate, sodium p-toluenesulfonate, potassium p-toluenesulfonate, sodium anthraquinone-1-sulfonate, anthraquinone-1-s Potassium fonate, sodium anthraquinone-2-sulfonate, potassium anthraquinone-2-sulfonate, sodium anthraquinone-1,5-disulfonate, potassium anthraquinone-1,5-disulfonate, sodium methanecarboxylate, potassium methanecarboxylate, Sodium ethanecarboxylate, potassium ethanecarboxylate, sodium propanecarboxylate, potassium propanecarboxylate, sodium butanecarboxylate, potassium butanecarboxylate, sodium octanecarboxylate, potassium octanecarboxylate, sodium trifluoromethanecarboxylate, trifluoromethanecarboxylic acid Potassium, sodium benzenecarboxylate, potassium benzenecarboxylate, sodium p-toluenecarboxylate, potassium p-toluenecarboxylate Mention may be made of the presence or absence. Of these alkali metal salts of inorganic or organic acids, potassium hexafluoroantimonate is preferred from the viewpoint of fast curability and economy of the photopolymerization initiator, and potassium hexafluorophosphate is preferred from the viewpoint of safety. .

  The amount of the alkali metal salt of the inorganic acid or organic acid used is 1 to 5 mol, preferably 1 to 3 mol per 1 mol of diphenyl sulfoxides. When the amount of the alkali metal salt of the inorganic acid or organic acid is less than 1 mol, the yield may be reduced. Moreover, when the usage-amount of the alkali metal salt of an inorganic acid or an organic acid exceeds 5 mol, there is no effect corresponding to a usage-amount and it is not economical. In addition, the alkali metal salt of an inorganic acid or an organic acid can also be used as an aqueous solution, and the concentration is 1 to 80% by weight, preferably 5 to 20% by weight.

  After adding an alkali metal salt of an inorganic acid or an organic acid to the reaction solution after the condensation reaction, the reaction is carried out for about 1 hour. The reaction temperature at that time is 10 to 80 ° C., preferably 20 to 50 ° C. When reaction temperature is less than 10 degreeC, reaction rate may become slow and there exists a possibility that reaction may require a long time. Moreover, when reaction temperature exceeds 80 degreeC, a side reaction tends to occur and there exists a possibility that a yield and purity may fall.

  After completion of the reaction, the aromatic sulfonium salt of the present invention can be obtained by adding an organic solvent such as dichloromethane to the reaction solution for extraction and column purification.

  The photopolymerization initiator of the present invention comprises an aromatic sulfonium salt represented by the general formula (1). In addition, you may use the said aromatic sulfonium salt individually or in mixture of 2 or more types.

  The photocurable composition of the present invention contains a photopolymerizable monomer and / or photopolymerizable polymer and the photopolymerization initiator.

  Examples of the photopolymerizable monomer and / or photopolymerizable polymer include monofunctional glycidyl ether compounds such as allyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, and 2-methyloctyl glycidyl ether; Multifunctional glycidyl ether compounds such as 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether; glycidyl (meth) acrylate, diglycidyl diphthalate, diglycidyl tetrahydrophthalate, etc. Glycidyl ester compounds of bisphenol A, bisphenol F, brominated bisphenol A, biphenol, Compounds obtained by glycidyl etherification of solcin, bisphenol novolak resin, phenol novolak resin, cresol novolak resin, etc .; 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxycyclohexylethyl-3,4- Cycloaliphatic epoxy compounds such as epoxycyclohexanecarboxylate, vinylcyclohexene dioxide, allylcyclohexene dioxide, 3,4-epoxy-4-methylcyclohexyl-2-propylene oxide, bis (3,4-epoxycyclohexyl) ether; 2 -Hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate; vinyl acetate, acrylonitrile, Tacrylonitrile, vinylidene chloride, vinyl chloride, styrene, sodium styrene sulfonate, 2-methyl styrene, vinyl toluene, tert-butyl styrene, chlorostyrene, vinyl anisole, vinyl naphthalene, ethylene, propylene, isopropylene, butadiene, chloroprene, vinyl ether Vinyl compounds such as vinyl ketone and N-vinyl pyrrolidone; tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate, lysine diisocyanate methyl ester, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, hexamethylene diisocyanate, 4,4- Bis (isocyanatocyclohexyl) methane, isophorone diisocyanate Isocyanate compounds such as trimethylene oxide, 3,3-dimethyloxetane, 3,3-dichloromethyloxetane, 3-ethyl-3-phenoxymethyloxetane, tri [(3-ethyl-3-oxetanylmethoxy) methyl Benzene, bis [(3-ethyl-3-oxetanylmethoxy) methylphenyl] ether, (3-ethyl-3-oxetanylmethoxy) oligodimethylsiloxane, spiro [bicyclo [2.2.2] octane-2,3 ' -Oxetane], spiro [7-oxabicyclo [2.2.1] heptane-2,3'-oxetane], 5-methyl-2-oxaspiro [3.5] nonane, spiro [3-methylbicyclo [2. 2.1] Oxetane compounds such as heptane-2,3′-oxetane]; 2,3-epithiopropylthiol Benzene, 2,3-epithiopropylthiobutane, 2,3-epithiopropylthiohexane, 2,3-epithiopropylthiobenzene, 2,3-epithiopropyloxybenzene, 2,3-epithiopropyloxy Butane, 2,3-epithiopropyloxyhexane, 2,3-epithiopropyl (meth) acrylate, bis [4- (2,3-epithiopropylthio) phenyl] sulfide, bis [4- (2,3 And episulfide compounds such as -epithiopropylthio) phenyl] ether and bis [4- (2,3-epithiopropylthio) phenyl] methane. Among these, an epoxy compound or an oxetane compound is desirable in order to make use of the high curability of the photopolymerization initiator. These photopolymerizable monomers and / or photopolymerizable polymers may be used alone or in combination of two or more. In addition, (meth) acryl in this specification shows an acryl or a methacryl.

  The amount of the photopolymerization initiator used is 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total amount of the photopolymerizable monomer and / or photopolymerizable polymer. When the usage-amount of a photoinitiator is less than 0.01 weight%, there exists a possibility that photocuring may become inadequate. Moreover, when the usage-amount of a photoinitiator exceeds 10 weight%, there exists a possibility that the hardened | cured material obtained by photocuring may become a low molecular weight hardened | cured material.

  The photocurable composition of the present invention can be produced, for example, by stirring and mixing a photopolymerizable monomer and / or photopolymerizable polymer and a photopolymerization initiator.

  Although the temperature at the time of stirring and mixing is not specifically limited, Usually, 0-100 degreeC, Preferably it is desirable that it is 20-50 degreeC. The stirring time is 0.1 to 12 hours, preferably 0.1 to 6 hours.

  Moreover, the photocurable composition of this invention may mix an organic solvent as needed. Specific examples of the organic solvent include ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, propylene carbonate, isopropyl alcohol and the like.

  The amount of the organic solvent used is 1 to 100% by weight, preferably 5 to 50% by weight, based on the total amount of the photopolymerizable monomer and / or photopolymerizable polymer.

  Furthermore, the photocurable composition of the present invention may contain a polymerization inhibitor such as 2,6-di-tert-butyl-p-cresol, hydroquinone, and p-methoxyphenol as necessary; eosin, methylene blue, malachite green, and the like. Sensitizers such as 2,4-diethylthioxanthone and 2-ethylanthraquinone; polymerization initiators other than the photopolymerization initiator of the present invention such as benzyldimethyl ketal and benzoin isopropyl ether may be mixed.

  The blending amount of the polymerization inhibitor is 0.001 to 5% by weight, preferably 0.01 to 1% by weight, based on the total amount of the photopolymerizable monomer and / or photopolymerizable polymer. The blending amount of the polymerization initiator other than the photopolymerization initiator of the present invention is 0.01 to 10% by weight, preferably 0.01 to 3% by weight, based on the total amount of the photopolymerizable monomer and / or photopolymerizable polymer. % Is desirable.

  The photocurable composition thus obtained can be cured by irradiating energy rays such as visible light and ultraviolet rays in a state where the organic solvent is evaporated or left.

  Specifically, for example, by applying a photocurable composition on a smooth aluminum plate or glass plate so that the film thickness is 0.1 to 200 μm, and irradiating energy rays such as visible light and ultraviolet rays. A resin can be obtained.

  Examples of the light source of energy rays such as visible light and ultraviolet light include a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a xenon lamp, a germicidal lamp, and a laser beam. The irradiation time varies depending on the light source to be used, the type of polymerization initiator, and the amount used, and thus cannot be defined unconditionally, but is usually 0.1 second to 10 hours, preferably 0.1 minute to 1 hour.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

Example 1
In a 300 mL four-necked flask, 4.8 g (0.02 mol) of 4,4′-difluorodiphenyl sulfoxide and 3.3 g (0.02 mol) of 2,2′-bithiophene were charged. 7 g (0.15 mol) was added dropwise at 20 ° C. over 1 hour. Subsequently, 4.8 g (0.045 mol) of acetic anhydride was added dropwise over 1 hour while maintaining the temperature at 25 to 35 ° C., and reacted at 30 ° C. for 5 hours.

  200 g of water was charged into a 1 L four-necked flask, and the reaction solution was added dropwise at 20 ° C. over 0.5 hour, followed by reaction for 1 hour. Subsequently, 3.7 g (0.02 mol) of potassium hexafluorophosphate was added at 20 ° C., and the mixture was reacted for 1 hour with vigorous stirring. After completion of the reaction, 50 g of dichloromethane was added, insoluble matters were filtered off, and liquid separation was performed to obtain 62 g of a dichloromethane layer. The dichloromethane layer was concentrated and purified with a column (Wakogel C-200, 200 g, hexane / ethyl acetate = 2/8, Rf = 0.35), bis (4-fluorophenyl) -5- (5′-acetyl) 1.8 g of -2,2'-bithienyl) sulfonium hexafluorophosphate was obtained. The yield based on 4,4'-difluorodiphenyl sulfoxide was 15.7%. The purity of the obtained bis (4-fluorophenyl) -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate was 99.9% as measured by high performance liquid chromatography. It was.

  The obtained bis (4-fluorophenyl) -5- (5'-acetyl-2,2'-bithienyl) sulfium hexafluorophosphate could be identified from the following physical properties.

Melting point: 141.6 ° C
Elemental analysis: C; 46.5%, H; 2.6%, F; 26.0%, S; 17.0%, P; 5.4% (theoretical value: C; 46.00%, H; (2.63%, F; 26.46%, S; 16.74%, P; 5.39%)
IR (cm ⁻¹ ): 1660 (C═O)
¹ H-nuclear magnetic resonance spectrum (270 MHz, CDCl ₃ ) δ (ppm): 2.55 (s, 3H), 7.37-7.46 (m, 3H), 7.61 (d, 1H), 7 .83-7.90 (m, 3H), 7.98 (d, 1H)
Maximum absorption wavelength: 354 nm

Example 2
In a 5 mL glass container, 2 g of a compound obtained by glycidyl etherification of bisphenol A (trade name of Yuka Shell; Epicoat 828), 0.11 g of propylene carbonate, bis (4-fluorophenyl) obtained in Example 1 A photocurable composition was obtained by charging 16 mg of -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate and stirring and mixing at 25 ° C. for 30 minutes.

Example 3
Example 2 except that the amount of bis (4-fluorophenyl) -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate used in Example 2 was changed from 16 mg to 80 mg. In the same manner as above, a photocurable composition was obtained.

Example 4
Example 2 except that the amount of bis (4-fluorophenyl) -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate used in Example 2 was changed from 16 mg to 40 mg. In the same manner as above, a photocurable composition was obtained.

Example 5
Example 2 except that the amount of bis (4-fluorophenyl) -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate used in Example 2 was changed from 16 mg to 4 mg. In the same manner as above, a photocurable composition was obtained.

Comparative Example 1
In Example 2, instead of 16 mg of bis (4-fluorophenyl) -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate, tris (4-methylphenyl) sulfonium hexafluoroantimonate A photocurable composition was obtained in the same manner as in Example 2 except that 16 mg was used.

Comparative Example 2
In Example 2, instead of 16 mg of bis (4-fluorophenyl) -5- (5′-acetyl-2,2′-bithienyl) sulfonium hexafluorophosphate, 16 mg of triphenylsulfonium tetrafluoroborate was used. Obtained a photocurable composition in the same manner as in Example 2.

  The measurement of the cure rate of the obtained photocurable composition was performed according to the following measuring method. The results are shown in Table 1.

Measurement of Curing Rate 1 g of the photocurable composition obtained in Examples 2 to 5 and Comparative Examples 1 to 2 was added to bar coater No. 22 (manufactured by Nippon Cedars Co., Ltd.) was applied onto an aluminum plate so as to have a film thickness of 50 μm, and a 60 W metal halide lamp (trade name: UVL-3001M2-N1 manufactured by USHIO INC.) Was used as the light source. Light irradiation was performed for 30 seconds at a light intensity of 200 mW / cm ² . After light irradiation, the coated surface was touched with a finger, and light irradiation was repeated until the stickiness disappeared, and the number of times of light irradiation was measured to determine the curing rate. In addition, if the frequency | count of light irradiation is 3 times or less, it can be judged that a cure rate is quick.

As can be seen from Table 1, the photocurable composition of the present invention can be judged to have a high curing rate because the number of times of light irradiation is 3 or less.

Claims (3)

The following general formula (1);

Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a cyano group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an acyl group. the, X ^- represents an inorganic acid ion or an organic acid ion).
An aromatic sulfonium salt represented by A photopolymerization initiator comprising the aromatic sulfonium salt according to claim 1. A photocurable composition comprising a photopolymerizable monomer and / or a photopolymerizable polymer and the photopolymerization initiator according to claim 2.