| abstract |
The composition of the present invention is excellent in compatibility, transparency and curability and give a cured coat of excellent gloss and of less smell, and cured products of excellent properties can be obtained by curing the composition. The present invention relates to an onium salt represented by the following formula (1): <IMAGE> (1) wherein Ar is a mono- to tetra-valent aromatic group, X is a bisphenylsulfonio group which may have a substituent, a is 1-4, b is 0 or 1-3, a+b is 1-4, n is 1-4, and Z is a halide represented by the following formula (3): MQm(OH)l(3) where M is a boron atom, a phosphorus atom, an arsenic atom or an antimony atom, Q is a halogen atom, m is 3-6, l is 0 or 1, and m+l is 4-6; a photopolymerization initiator containing the onium salt as an active ingredient; an energy ray-curable composition containing the initiator; and a cured product. |