Polycarbonates containing low levels of methyl salicylate prepared by a melt polymerization in a reactive extruder

• Main Authors: DAVIS PETER, LOOIJ HANS
• Format: Patent
• Language: English
• Published: 21.06.2007
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CHEMISTRY; COMPOSITIONS BASED THEREON; MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

Polycarbonate is prepared by reactive extrusion on a reactive extruder. A method incorporates the steps of introducing a polycarbonate oligomer, an activated carbonate, and a transesterification catalyst to the extruder through a feed section. The extruder has a feed section, a polycarbonate exit section, and a reaction section between the feed section and the polycarbonate exit section. The reaction section has one or more devolatilization units, wherein each devolatilization unit incorporates an array of vent-conveying sections and conveying sections arranged in a configuration of: (C V C)x(V)n, and/or (V C V)x(C)n. (V) is a vent-conveying section, (C) is a conveying section, x is 1 or more, and n is 1 or 0. The extruder screw in the vent-conveying sections and the conveying sections in each devolatilization unit have conveying elements or conveying elements and mixing elements and no elements that create a melt seal in the devolatilization unit. The method further includes the step of extruding the reaction components at a temperature in a range between 100° C. and 500° C., wherein during the extrusion of the reaction components, activated carbonate residue is removed through the vent-conveying sections.