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

A sulfonium salt formed of a sulfonium cation selected from a group indicated by general formulas (1), (2), and (3) described below and a gallate anion represented by formula (a),

• wherein formula (1), R1 to R4 each independently represent an alkyl group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group, an aryl group, an aryloxy group, an optionally substituted silyl group, or a halogen atom;
• a, b, c, and d each represent the number of occurrences of each of R1 to R4;
• a represents an integer of 1 to 5;
• c and d represent an integer of 0 to 5;
• and b represents an integer of 0 to 4
• wherein formula (2), R5 to R8 each independently represent an alkyl group, or an alkoxy group;
• e, f, g, and h each represent the number of occurrences of each of R5 to R8;
• e and g represent an integer of 0 to 4;
• f represents an integer of 0 to 3;
• h represents an integer of 0 to 5;
• x represents an optionally substituted phenyl group or an optionally substituted thioxanthonyl group;
• Y represents —O—, —S—, —SO—, or —SO2—,
• wherein formula (3), n represents an integer of 1 to 3;
• R9 to R10 each independently represent an alkyl group, or an alkoxy group;
• i and j each represent the number of occurrences of each of R9 to R10;
• i and j represent an integer of 0 to 4;
• Q represents single bond, —O— or —S—;
• Ar represents a phenyl group, and some of hydrogen atoms in the phenyl group may be substituted with an alkyl group, or an alkoxy group;
• Z represents an alkylene group having 2 to 6 carbon atoms or a phenylene group or naphthylene group,
• wherein R13 to R16 each independently represent a phenyl group or a perfluoroalkyl group, and some of hydrogen atoms in these groups may be substituted with a group selected from a perfluoroalkyl group, a perfluoroalkoxy group, a nitro group, a cyano group, an acyl group and a halogen atom.