Polymerizable ultraviolet stabilizers for unsaturated polyester-based bulk molding compounds

Abstract

Monomeric compounds that protect against ultraviolet (UV) exposure, e. g. 2-hydroxy-4-acryloyloxybenzophenone (HABP), 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate (BTEM), and 4-acryloyloxy-1,2,2,6,6-pentamethylpiperidine (APMP), were used as UV stabilizers for unsaturated polyester-based bulk molding compounds (BMCs). HABP and APMP were synthesized by reacting acryloyl chloride with 2,4-dihydro-xybenzophenone and 1,2,2,6,6-pentamethyl-4-piperidinol, respectively. The molded BMC samples were obtained using actual formulations containing these UV stabilizers, and the UV stability of the samples was estimated using a color difference meter. The results showed that HABP and BTEM afforded good protection against UV light, and these compounds showed a synergistic effect. APMP also showed a synergistic effect, but only when a small amount of the compound was used. These results were compared with the results obtained when copolymers of HABP and BTEM were used as UV stabilizers. The results showed that the polymerizable UV stabilizers demonstrated better protection against UV exposure, when they were added directly to the formulation of BMC, compared to the addition of copolymers as UV stabilizers.