Printed circuit cover coating comprising an ultraviolet radiation sensitive acrylic resin

Claim 1

Method for the preparation of photopolymerizable acrylic resin which comprises the steps of: a. esterifying castor oil with chlorendic anhydride in the presence of an amine catalyst at a temperature within the range of 120°-150° C for a time period ranging from 16-2 hours, the lower temperatures corresponding with the longer reaction times and the converse, so yielding a chlorendic anhydride half ester, b. admixing the resultant ester with a cure retardant, from 5 to 20 parts per 100 parts of resin of an acrylic functional monomer selected from the group consisting of methyl acrylate, butyl acrylate, ethyl hexyl methacrylate, alkyl acrylate, and methyl methacrylate, and a reagent having acrylic functionality, selected from the group consisting of glycidyl acrylate, glycidyl methacrylate and a mixture of glycidyl methacrylate and butyl glycidyl ether, said reagent being employed in an amount sufficient to assure that at least 50% of the carboxyl groups present in the ester system are reacted therewith, so yielding an acrylic ester, and c. exposing the acrylic ester to a source of ultraviolet radiation for a time peroid sufficient to effect curing thereof.