Patent GB-1098753-A (GB)
Title: Production of polycarbonates
IPC: C08L69/00
Filed: 1965-02-08
Abstract: 1,098,753. Polycarbonate films and fibres. EASTMAN KODAK CO. Feb. 8, 1965 [Feb. 6,1964],No. 5304/65. Heading B5B. The heat distortion temperature (defined as that temperature at which 2% shrinkage or extension occurs) of a film or fibre made from a polycarbonate is increased by heating the film or fibre while under a tension of between 1 and 5 pounds per square inch to a temperature of at least the second-order transition temperature (defined as that temperature at which % shrinkage or extension occurs under a load of 5 pounds per square inch) of the polycarbonate for a time sufficient to cause appreciable shrinkage. The film or fibre preferably is heated, for example by hot air, to a temperature (previously determined by experiment) at which maximum shrinkage occurs and is held at this temperature for one minute. The polycarbonate is prepared by the reaction of one or more diols and either phosgene or a bischloroformate. The bischloroformate is prepared from phosgene and one or more aliphatic, alicyclic or aromatic diols; examples of suitable diols are listed in the Specification. At least 50 mole per cent of the total diol component used in the preparation of the polycarbonate must consist of at least one aromatic diol. Suitable aromatic diols are those in which the hydroxy functions are on the same aromatic ring, for example hydroquinone and 5,6,7,8-tetrahydro-1,4-naphthalenediol, on different fused aromatic rings, for example 2,5-naphthalenediol, or on different aromatic rings connected by aliphatic, alicyclic or aromatic radicals. Examples of the latter classes are the gem-bisphenols, for example 4,4<1>- isopropylidenediphenol (A), 4,4<1>-isopropylidenebis(2,6-dibromophenol) and 4,4<1>-ethylidenediphenol; 4,4<1> - (4 - chloro - alpha - methylbenzylidene)diphenol; and 4,4<1> - cyclohexylidenediphenol and 4,4<1> - (cyclohexylmethylene)diphenol. Other suitable gem-bisphenols include those in which the two phenol or substituted phenol groups are attached to a single carbon atom of the gem-bivalent connecting radical, which radical is saturated and contains a saturated polycyclic structure including a bicyclic member which contains at least one atomic bridge; examples of such gem-bisphenols are those which contain the norbornane ring system. The Specification lists such suitable gem-bisphenols (or polycyclic structures from which such gem-bisphenols are derived), typical examples being 4,4<1>-(2-norbornylidene)-diphenol (B), 4,41 - (2 - norbornylmethylene)diphenol (C) and 4,4<1>-(hexahydro-4,7-methanoindan-5- ylidene)diphenol (D). The aromatic diol component may consist of one or a plurality of diols; suitable aromatic diol mixtures include an equimolar mixture (E) of (A) above and a 2,5- and 2,6-norbornanediol isomer mixture, a 5 to 1 molar ratio mixture (F) of (D) above and 4,41 - isopropylidenebis(2,6 - dibromophenol), and a 1 to 2 molar ratio mixture (G) of 5,6,7,8- tetrahydro - 1,4 - naphthalenediol and (A) above. Examples describe the treatment of films formed from each of diol components (A) to (G), the increase in the heat distortion temperature (measured by a 2% film length change under a tension of 5 pounds per square inch) ranging between 25 and 54 C.