Method for producing bis- 4-(diphenylsulfonio)pheny! sulfide bis- M.X.sub. 6 photoinitiator

摘要

A highly effective photoinitiator for cationic polymerization of monomer formulations is prepared by reacting diphenyl sulfide with chlorine gas in a Friedel-Crafts reaction in an organic solvent to form bis- 4-(diphenylsulfonio)phenyl! sulfide dichloride. This product is recovered and then reacted in an aqueous solution with a compound having the formula T.MF.sub.6 wherein M is one of phosphorus, antimony or arsenic and T is hydrogen or a metal whose halide salt is water soluble. The two compounds react in the aqueous medium to produce a precipitate which includes at least about 50 percent by weight bis- 4- (diphenylsulfonio) phenyl! sulfide bis-MF.sub.6, and this precipitate may be recovered and dried for utilization without further purification if so desired. Purification may be effected by dissolving the dried product in an organic solvent, cooling the solvent to precipitate the impurities, and thereafter recovering relatively pure bis- 4-(diphenylsulfonio) phenyl! sulfide bis-MF.sub.6 by chilling the solvent solution to form a precipitate, and then separating and drying the precipitate. The preferred compounds are those wherein the substituent M is phosphorus so that the product comprises bis- 4-(diphenylsulfonio)phenyl! sulfide bis- hexafluorophosphate. The cationic polymerization processes utilize the photoinitiator in an amount equal to about 0.5-6.0 percent by weight of the monomer therein.