| 摘要 |
A polycarbonate composition comprises a mixture of (a) a homopolycarbonate of 2,2-bis (4-hydroxyphenyl) propane and (b) a homopolycarbonate of 2,2-bis(3,5-dichloro-4-hydroxyphenyl) propane; the mixture comprising 40-80 mole per cent of units of polycarbonate (a) and 20-60 mole per cent of units of polycarbonate (b). Preferably the mixture is dissolved in a chlorinated hydrocarbon (e.g. methylene chloride) and cast into a film which may be used as a packaging material, an adhesive tape base, a kinescope recording tape, or a condenser dielectric or a photographic base (see Division G2). The polycarbonates may be made by reacting the bisphenol with phosgene in the presence of aqueous sodium hydroxide solution, methylene chloride and benzyltriethylammonium chloride, terminating the polycondensation by adding acetic acid, diluting the methylene chloride layer with further methylene chloride and then precipitating the polycarbonate with methanol. |
