Trihalogenated hydrocarbons as co-photoinitiators

Claim 1

In an ultraviolet curable titanium dioxide pigmented protective coating composition, said coating based on the total weight of the curable composition, containing about 40 to about 100 percent, by weight, of an alpha beta ethylenically unsaturated vinyl polymerizable compound containing at least about two sites of vinyl polymerizable unsaturation, about 60 to about 0 percent of another alpha beta ethylenically unsaturated vinyl polymerizable composition containing no more than about one site of vinyl unsaturation, and up to about 15 percent, by weight of the curable composition, of an ultraviolet organo photoinitiator, the improvement of which consists essentially of utilizing as an additional photoinitiator about 25 to about 200 weight percent, based upon the standard photoinitiator, of a terminal trihalogen compound having the general formula ##STR11## wherein X is bromine, chlorine, or iodine, or mixtures thereof, A is bromine, chlorine, or iodine, a C 1 -C 12 hydrocarbon radical, a C 1 -C 12 halogenated hydrocarbon, or a C 1 -C 12 amine, carboxylic acid, alcohol, ketone, or aldehyde, and when X is iodine, A may, in addition, by hydrogen, wherein the A substituents are not interferingly reactive with the ultraviolet cure mechanism, and exposing the photoinitiator-containing coating to ultraviolet light at a power of about 200 watts for up to about 1 minute/linear foot.