Thermoplastic polycarbonate(s) - useful as a source of carbon di:oxide blowing agent for prodn. of thermoplastic polycarbonate foam

摘要

Thermoplastic polycarbonates (I) are useful for foaming thermoplastic polycarbonates. Also claimed is a process for the prodn. of polycarbonate foam prods., by mixing (I) (with Mw = 5000-50,000) with 0.01-1 mol. % transesterification catalysts and 0.1-5 mol. % aromatic polycarboxylic acids and/or 0.1-5 mol. % water and opt. with 0.1-5 mol.% aliphatic hydroxycarboxylic acids and/or aliphatic alcohols (w.r.t. mols. of carbonate units of formula -O-R-O-CO- (with R = diphenolate residuel, and injection moulding or extruding this mixt. at 210-340 deg. C, with reaction times of 0.5-5 mins. Foam prods. (II) obtd. by this process are also claimed as such. Specifically the above process is carried out with addn. of normal additive(s); additive-contg. polycarbonate foam prods. (II) are also claimed. USE/ADVANTAGE - Foam prods. (II) are useful, eg. for the prodn.of lamp covers, housings, office equipment, parts of cabinets, etc. The invention enables the prodn. of thermoplastic polycarbonate foam by using, as blowing agent, the CO2 produced by controlled partial decompsn. of (I); the prods. (II) have a light colour, uniformly fine pore structure and smooth surfac