Phosphite esters of (4,6)-dialkyl pyrogallols - used as light and heat stabilisers for plastics pref. in synergetic mixts.

摘要

New phosphite esters of 4,6-dialkyl pyrogallols have formula (I) (where R1 is 1-30C alkyl or alkylene or opt. alkyl-substd. Ph or phenylene or a naphthyl or naphthylene gp. R2 and R3 are opt. different 1-4C alkyl. X is -O- or -S- and n is 1 or 2). (I), together with standard heat- and light-stabilisers, are used for heat- and light-stabilising plastics, e.g. polyurethanes, polyesters, polyamides, polyvinylidene chloride, PVC, ABS-copolymers, impact-resistant polystyrene and esp. polyolefins. (I) have high heat- and light-stabilising activity, partic. in synergetic mixts. with standard stabilisers. E.g. in stabilising polypropylene, addn. of 0.3 wt. % (I) to standard stabiliser mixt. increased test sample life from 605 to 880 hrs. Phenolic OH vicinal to phosphite ester bond increases anti-oxidative and light-stabilising activity of (I). (I) are solid and can be admixed to plastics together with the other solid stabilisers. In an example, methyl-(4,6-di-tert. butyl)pyrogallol phosphite was prepd. from 0.7 mol 4,6-di-tert.-butyl pyrogallol and 1.5 mol. trimethyl phosphite.