| abstract |
Polyesters (I) and polyester-urethanes (II) are stabilised against discolouration or hydrolytica degradation, and proportion of isocyanate split off by (II) is reduced, through incorporation, and (I) or (II) (A) 0.5-4% (all pts. wt.) aromatic carbodimide and (B) 0.01-1.5% benzohydroquinone deriv. or naphthohydroquinone deriv.. Pref. (I) is polyethylene or polybutylene terephthalate or thermoplastic polyether-ester elastomer. (II) is urethane contg. polyether and hydrolysable polyester bonds. (A) is 2,2',6,6'-tetra- isoapropyldiphenylcarbodiimide, homopolymeric carbodi-imide from 1,3,5-triisopropyl-2,4-isocyanatobenzene (III), or heteropolymeric carbodi-imide from (III) and/or 2,6-di-isopropylphenyl isocyanate. (B) is 2-tert.butylbenzo-1,4-hydroquinone or 2,5-di-tert.butylbenzo 1,4-hydroquinone (IV). |