GB786144A - Thermoplastic compositions having improved light stability - Google Patents

Abstract

Thermoplastic synthetic resins are light stabilized by incorporating in the polymer from 0.1 to 10 per cent by weight of a dibenzoyl resorcinol compound having the general formula: <FORM:0786144/IV (a)/1> wherein R1 to R5 are selected from hydrogen, chlorine, bromine, fluorine, an alkyl group having from 1 to 8 carbon atoms, and -COOR7 wherein R7 is selected from an alkyl group of from 1 to 8 carbon atoms, phenyl, monochlorophenyl, monobromophenyl, monoalkylphenyl and R6 from R1, benzoyl, benzoyl substituted with R1 and R2; and the compound does not contain more than four bromine atoms, nor more than three fluorine atoms, nor more than three -COOR7 groups and not more than one -COOR7 group attached to any benzene group. Specified compounds are 2,4-dibenzoyl and 4,6-dibenzoyl resorcinol, or 6-chlororesorcinol, 2,4-di(4-chloro-or 4-bromo- or 4-fluoro-benzoyl) resorcinol, 2,4-di(2,4-dichloro- or dibromo- or 2,4,6-trichlorobenzoyl) resorcinol, 2,4-di(4-methyl or 4-butylbenzoyl) resorcinol, 2,4-di(monomethylphthaloyl) resorcinol, and the methyl, butyl, 2-ethylhexyl, phenyl, 4-chlorophenyl, 4-bromophenyl esters of 3,5-dibenzoyl, 2,4-dihydroxybenzoic acid. The resin mixtures may also contain plasticizers, fillers, pigments and other heat and light stabilizers. The resin may be polystyrene, polyethylene, polyacrylonitrile, polyvinyl chloride and copolymers of vinyl chloride and/or vinylidene chloride. Plasticizers mentioned are acetyl triethyl citrate, acetyl trioctyl citrate, the pentaerythritol tetraesters of a mixture of saturated fatty acids, polyesters of propylene glycol and adipic and lauric acids, polyesters of propylene glycol and sebacic acid, chlorinated diphenyl and chlorinated terphenyl. The other stabilizers may be 2-hydroxy-5-chlorobenzophenone, tetrasodium pyrophosphate, sodium tripolyphosphate, or disodium lauryl phosphate.