Onium salts and the use thereof as photoinitiators

A composition of matter comprising a material curable by a Bronsted acid and a compound having the formula:

• ##STR15## wherein:
• R' represents one of the following chromophores:
• ##STR16## L represents one of the following linkages:
• ##STR17## wherein n represents 1 to 12;
• J, R", R'" and R"", taken together, represent one of the following groups:
• ##STR18## ##STR19## wherein Ar represents an optionally substituent aryl group;
• and W represents BF.sub.4, ClO.sub.4, AsF.sub.6, PF.sub.6, CF.sub.3 SO.sub.3, CH.sub.3 SO.sub.3, SnCl.sub.4, FeCl.sub.4, BiCl.sub.4 or SbF.sub.6.

A method of curing which comprises exposing to visible radiation (1) a material curable by a Bronsted acid and (2) a sulfonium, selenonium, arsonium, ammonium or phosphonium salt comprising:

• a chromophore which absorbs said visible radiation, said chromophore exhibiting a higher energy occupied molecular orbital than at least one other substituent attached to the S, Se, As, N or P atom of said salt;
• an insulating group which links said chromophore to the S, Se, As, N or P atom of said salt, said insulating group essentially preventing .pi. resonance between said chromophore and the other substituents in said salt;
• at least one substituent comprising an electron withdrawing group and exhibiting a lower unoccupied molecular orbital than said chromophore;
• and,
• an anion;
• said salt being capable, upon exposure to said visible radiation, of forming a Bronsted acid.

A method of curing which comprises exposing to visible radiation (1) a material curable by a Bronsted acid and (2) a compound having the formula:

• ##STR26## wherein:
• R' represents an electron donating chromophore group which absorbs said visible radiation, and which exhibits a higher energy occupied molecular orbital than at least one of R", R'" and R"";
• R" represents the same substituent as R' or R'", an optionally substituted aryl group or an optionally substituted alkyl group having from 1 to 18 carbon atoms;
• L represents a linking group which essentially prevents .pi. resonance between R' and the remainder of the compound;
• R'" represents an electron withdrawing alkyl, aryl or heterocyclic group;
• J represents an S, Se, As, N or P atom;
• and
• when J represents As, N or P, R"" represents the same substituent as R', R" or R'" and, when J represents an S or Se atom, R"" represents O or an electron pair;
• and,
• W.sup..crclbar. represents an anion capable of forming a Bronsted acid having a pKa of less than 7,
• said compound being capable, upon exposure to visible said radiation, of forming a Bronsted acid.

A composition of matter comprising a material curable by a Bronsted acid and a salt having the following formula:

• ##STR27## wherein:
• R' represents an electron donating chromophore group which absorbs visible radiation, and which exhibits a higher energy occupied molecular orbital than at least one of R", R'" and R"";
• R" represents the same substitutent as R' or R'", an optionally substituted aryl group or an optionally substituted alkyl group having from 1 to 18 carbon atoms;
• L represents orthophenylene;
• R'" represents an electron withdrawing alkyl, aryl or heterocyclic group;
• J represents an S, Se, As, N or P atom;
• and
• when J represent As, N or P, R"" represents the same substituent as R', R" or R'" and, when J represents a S or Se atom, R"" represents O or an electron pair;
• and,
• W.sup..crclbar. represents an anion capable of forming a Bronsted acid having a pKa of less than 7,
• said compound being capable, upon exposure to visible radiation of a wavelength absorbed by said chromophore, of forming a Bronsted acid.

A method of curing which comprises exposing to visible radiation (1) a material curable by a Bronsted acid and (2) a compound having the formula:

• ##STR32## wherein:
• R' represents an electron donating chromophore group which absorbs said visible radiation, and which exhibits a higher energy occupied molecular orbital than at least one of R", R'" and R"";
• R" represents the same substituent as R' or R'", an optionally substituted aryl group or an optionally substituted alkyl group having from 1 to 18 carbon atoms;
• L represents orthophenylene;
• R'" represents an electron withdrawing alkyl, aryl or heterocyclic group;
• J represents an S, Se, As, N or P atom;
• and
• when J represents As, N or P, R"" represents the same substituent as R', R" or R'" and, when J represents an S or Se atom, R"" represents O or an electron pair;
• and,
• W.sup..crclbar. represents an anion capable of forming a Bronsted acid having a pKa of less than 7,
• said compound being capable, upon exposure to visible said radiation, of forming a Bronsted acid.