Maleate vinyl ether UV-cured coatings: Effects of composition on curing and properties

The effect of the composition of the maleate polyesters and vinyl ethers used on UV-curing and film properties has been investigated. Linear unsaturated polyesters were prepared from maleic anhydride with succinnic anhydride and 1,5-pentane diol. The equivalent weight and molecular weight of the unsaturated polyesters was varied. Coating formulations containing these unsaturated polyesters, triethylene glycol divinyl ether and a free radical photoinitiator were crosslinked in the presence of UV light. A. ratio of vinyl ether equivalents to maleate equivalents of 1:1 was preferred for optimal crosslinking. Photoinitiators 2-hydroxy-2-methyl propiophenone and diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide produced the fastest cure. Photoinitiator concentration had little effect on the degree of cure of the coating. Diethyl maleate and isobutyl vinyl ether were effective for reducing viscosity but reduced cure speed. A vinyl ether urethane oligomer was synthesized which enhanced flexibility and toughness of the coatings when substutited for triethylene glycol divinyl ether.