US 5,470,994 A · Sulfonium salts and the use thereof as photoinitiators

Abstract

Sulfonium and oxysulfonium salts, useful as photoinitiators, have directly attached to the sulfur atom thereof: at least one aromatic or heterocyclic aromatic substituent containing at least 14 aromatic atoms and having a removable positive hydrogen ion, said substituent exhibiting a higher energy occupied molecular orbital than at least one other substituent directly attached to said sulfur atom; and at least one substituent comprising an electron withdrawing group and exhibiting a lower energy unoccupied molecular orbital than at least one other substituent directly attached to said sulfur atom; said salt being capable, upon exposure to visible radiation, of undergoing irreversible intramolecular rearrangement to form a Bronsted acid comprising the anion of said salt and said removable positive hydrogen ion.

Claims4

Dependent claims

A sulfonium salt photoinitiator which absorbs visible radiation and which has the formula:

##STR2## wherein:
R' represents an electron donating anthryl or naphthacenyl group, said group having a removable positive hydrogen ion;
R" represents a phenyl group, a naphthyl group, an alkyl group having from 1 to 18 carbon atoms or the same substituent as R' or R"';
R'" represents a cyano or halogen substituted methyl group or a cyano or halogen substituted benzyl group;
and,
w-- represents an anion capable of forming a Bronsted acid having a pKa of less than 7;
said photoinitiator being capable, upon exposure to visible radiation, of undergoing irreversible intramolecular rearrangement to form a Bronsted acid comprising w-- and said removable positive hydrogen atom of R'.

4 more elements

Dependencies are inferred from the claim text.

Sulfonium salts and the use thereof as photoinitiators

Life of this patent

Sulfonium salts and the use thereof as photoinitiators

Life of this patent

Abstract

Claims4