Sulfonium salt, photoacid generator, and photocurable composition and cured body thereof

1. A sulfonium salt represented by formula (1):

wherein R 1 is a group represented by formula (2); R 2 and R 3 each represent an aryl group having 6 to 30 carbon atoms, a heterocyclic hydrocarbon group having 4 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, or an alkynyl group having 2 to 30 carbon atoms, wherein some hydrogen atoms of the aryl group, the heterocyclic hydrocarbon group, the alkyl group, the alkenyl group, or the alkynyl group may be substituted with a substituent (t); S represents a sulfur atom; and X − represents a monovalent polyatomic anion:

wherein R 4 to R 6 each represent an alkyl group, a hydroxy group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an arylthiocarbonyl group, an acyloxy group, an arylthio group, an alkylthio group, an aryl group, a heterocyclic hydrocarbon group, an aryloxy group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a hydroxy(poly)alkyleneoxy group, an amino group, a cyano group, a nitro group, or a halogen atom; k, m, and n represent the number of R 4 , the number of R 5 , and the number of R 6 , respectively; k is an integer of 0 to 4; m is an integer of 0 to 3; n is an integer of 0 to 4; A is a group represented by —S—, —O—, —SO—, —SO 2 —, or —CO—; O represents an oxygen atom; and S represents a sulfur atom.

2. The sulfonium salt according to claim 1 , wherein R 2 and R 3 are each an aryl group having 6 to 30 carbon atoms or a heterocyclic hydrocarbon group having 4 to 30 carbon atoms.

3. The sulfonium salt according to claim 1 , wherein R 2 or R 3 is a phenyl group,

A is a group represented by —S—, and k, m, and n are each 0.

4. The sulfonium salt according to claim 1 , wherein R 2 or R 3 is a thioxanthonyl group, A is a group represented by —S—, and k, m, and n are each 0.

5. The sulfonium salt according to claim 1 ,

wherein X − is an anion represented by MY a − , (Rf) b PF 6-b − , R 7 c BY 4-c − , R 7 c GaY 4-c − , R 8 SO 3 − , (R 8 SO 2 ) 3 C − , or (R 8 SO 2 ) 2 N − , wherein M represents a phosphorus atom, a boron atom, an arsenic atom, or an antimony atom; Y represents a halogen atom; Rf represents an alkyl group in which 80 mol % or more of hydrogen atoms are substituted with fluorine atoms; P represents a phosphorus atom; F represents a fluorine atom; R 7 represents a phenyl group in which at least one hydrogen atom is substituted with a halogen atom, a trifluoromethyl group, a nitro group, or a cyano group; B represents a boron atom; Ga represents a gallium atom; R 8 represents an alkyl group having 1 to 20 carbon atoms, a perfluoroalkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms; S represents a sulfur atom; 0 represents an oxygen atom; C represents a carbon atom; N represents a nitrogen atom; a represents an integer of 4 to 6; b represents an integer of 1 to 5; and c represents an integer of 1 to 4.

6. The sulfonium salt according to claim 1 , wherein X − is an anion represented by SbF 6 − , AsF 6 − , PF 6 − , BF 4 − , (CF 3 CF 2 ) 3 PF 3 − , (C 6 F 5 ) 4 B − , ((CF 3 ) 2 C 6 H 3 ) 4 B − , (C 6 F 5 ) 4 Ga − , or ((CF 3 ) 2 C 6 H 3 ) 4 Ga − .

7. A photoacid generator comprising the sulfonium salt according to claim 1 .

8. An energy ray-curable composition comprising the photoacid generator according to claim 7 and a cationically polymerizable compound.

9. A cured body obtained by curing the energy ray-curable composition according to claim 8 .