GB896266A - High molecular weight polycarbonates - Google Patents

Abstract

Cross-linkable aromatic polycarbonates having carboxylic acid ester groups as side-chains are made by reacting (a) an ester of a compound containing two phenolic hydroxyl groups and one or more carboxyl groups with a volatile monohydroxy compound with (b) phosgene, a bis-chlorocarbonic acid ester of a dihydroxy compound or, if mild reaction conditions are used, a dialkyl or diaryl carbonate. Specified esters are 2:2-(4:41-dihydroxydiphenyl)-butyric acid ethyl ester, 3:3-(4:41-dihydroxy-3:31-dimethyldiphenyl)-valerianic acid ethyl ester, 3:5-dihydroxybenzoic acid ethyl ester, bis-(4-hydroxy-3-carboxylic acid-phenyl ester-phenyl) methane and bis(4-hydroxy-3-carboxylic acid-ethyl ester phenyl) methane. These esters may be used in admixture with other aliphatic, cycloaliphatic and aromatic dihydroxy compounds (many specified). Monohydroxy compounds (e.g. phenol or tertiary butyl phenol) may also be included. The polycarbonates are soluble in benzene, methylene chloride, chloroform, ethylene chloride dioxane, tetrahydrofurane, ethyl acetate, dimethyl formamide and a mixture of anisole and diphenyl ether and may be worked up from solution or from the melt into foils, threads, profiles, tubes, injection moulded bodies, lacquers or coatings. During or after their working up, the polycarbonates are cross-linked by heating alone or with di-or higher polyhydroxy compounds (including hydroxyl group containing polyethers and polyesters) or their esters. Cross-linking may be accelerated by the addition of a transestification catalyst, e.g. boric acid, toluene sulphonic acid or boron phosphate, or the oxides, alcoholoates, phenolates, hydrides, carbonates or acetates of the alkali metals, the alkaline earth metals, zinc or titanium. In examples, polycarbonates are made by reacting bisphenol-A, one of the above specified esters, p-tertiary butyl phenol and phosgene in the presence of aqueous sodium hydroxide solution, methylene chloride, triethylamine and sodium isobutylnaphthalene sulphonate. The polycarbonates are made into films and subsequently crosslinked. Specification 896,265 is referred to.