| abstract |
1341318 Polycarbonates BAYER AG 22 Dec 1971 [22 Dec 1970] 59552/71 Heading C3R A high molecular weight polycarbonate with a glass transition temperature of at least 180 C. contains only structural units of the formula in which R is CH 3 , C 2 H 5 , or CH(CH 3 ) 2 and X is a direct bond, an alkylene or alkylidene radical with 1-5 carbon atoms, a cycloalkylene or cycloalkylidene radical with 5-15 carbon atoms, an ether bond or a keto bond. The polycarbonate may be prepared (a) by reacting an alkali metal salt of the corresponding bisphenol in aqueous solution or suspension in the presence of an inert solvent with phosgene and/or a bischlorocarbonic acid ester of the bisphenol or (b) by reacting a bischlorocarbonic acid ester of the corresponding bisphenol in a mixture of an inert solvent and aqueous caustic alkali solution, both reactions being initiated by adding 10-200 mol per cent, based on the bisphenol, of a tertiary amine and the reaction carried out for 6 minutes to 5 hours. The examples describe polycarbonates derived from 2,2-bis- (3,5 - dimethyl - 4 - hydroxy - phenyl) propane, optionally with 2,6-dimethylphenol as chain stopper, bis - (3,5 - dimethyl - 4 - hydroxyphenyl)methane, a mixture of the above bisphenols, and 1,1-bis-(3,5-dimethyl-4-hydroxyphenyl) cyclohexane. |