Characterization of urethane functional hindered amine light stabilizers

Abstract

New polymerizable urethane-functional monomers containing hindered-amine structures have been synthesized by reaction of m-isopropenyl-α, α-dimethylbenzyl isocyanate with hindered piperidines and their copolymers with styrene and methyl methacrylate have been prepared by free-radical initiation. The structures, thermal stabilities, solubility parameters and stabilizing effect of these new HALS have been assessed. The results show that the monomers have good photoprotecting effect. The effect of the copolymers is less good because of the lower content of the piperidine nitrogen. The extraction resistance to water at 90°C is good for the copolymers but poor for the monomers. UV and ESR experiments confirm that the photoprotecting mechanism is still due to the scavenging action of nitroxyl radicals. © 1993.