Lichtbeständige äthylencopolymere. Synthese und abbau durch lichteinwirkung

New photostable polyolefin systems containing controlled concentrations of covalently bound ultraviolet screening groups were prepared by copolymerization and rearrangement techniques. This chemical bonding approach, contrasted to the classical additive technique, avoids loss of ultraviolet absorber, permits relatively high concentrations of absorber to be used, and results in better weatherability. Polymers with bound o-hydroxybenzophenone units have the best ultraviolet stability of the absorbers studied. Ethylene/4-methacryloxy-2-hydroxybenzophenone copolymers were blended with high density polyethylene or isotactic polypropylene, permitting high concentrations of polymeric ultraviolet absorber to be retained in these polyolefins for the first time. Other ulraviolet absorbing comonomer units studied include allyl or acryloxy derivatives of o-hydroxyacetophenones, salicylates, 1-(o-hydroxyphenyl)-1,3-propanedione, and dibenzoylmethane.