Polycarbonates with increased crystallizability

摘要

Polycarbonates having good crystallizability and containing ester linkages are made by polycondensing a mixture of (a) bisphenol A or an alkali metal salt thereof, (b) a bischloroformate of bisphenol A and (c) a bischloroformate or bisbromoformate of a bis(hydroxyalkyl) ester of a dicarboxylic acid; the mixture containing not more than 10 mol per cent of (c) based on the sum of (b) and (c). Polycondensation is preferably effected by an interfacial process using an onium compound as catalyst. The polycarbonates may be made into films or fibres which may be crystallized by heating them to a temperature between 10 DEG C. above the glass transition temperature and 10 DEG C. below the crystalline melting point. In examples, ingredient (c) was the bischloroformate of (2)-(13) bis(b -hydroxyethyl) terephthalate; (14)-(18) bis(d -hydroxybutyl) terephthalate; (19) bis(b -hydroxyethyl) isophthalate; (20) the bis(b -hydroxyethyl) ester of pyridine-2,5-dicarboxylic acid; (21) bis(b -hydroxyethyl) adipate.