Patent ID: 8546522
Filing Date: 2013-10-01
Classification: B29C,B29K,C08G,C08J

Abstract:
1. A method for preparing a high molecular weight polycarbonate resin using fine round powdery polycarbonate, comprising: (A) supplying an aromatic dihydroxy compound and diarylcarbonate to stirred polymerization apparatus and melt-polymerizing an aromatic dihydroxy compound and diarylcarbonate into amorphous polycarbonate or a prepolymer thereof with a weight-average molecular weight of 20,000 g/mol or less; (B) extruding the melted amorphous polycarbonate or a prepolymer thereof into a fine round powdery amorphous polycarbonate or a prepolymer thereof without performing a separate grinding process, by an extruder with a cutter and an extrusion die having microscopic holes with a size of 100 to 900 microns; (C) surface-crystallizing the extruded fine round powdery amorphous polycarbonate or prepolymer thereof in the presence of a solvent or dispersion medium which directly contacts the extruded fine round powdery amorphous polycarbonate or prepolymer thereof after said extruding, wherein a non-solvent is used as the dispersion medium for maintaining the extruded fine round powdery amorphous polycarbonate or prepolymer thereof in a fine round powder shape; (D) drying the fine round powdery polycarbonate or prepolymer thereof and maintaining the fine round powder shape, wherein the dispersion medium is separated from the fine round powdery polycarbonate or prepolymer thereof, returned to a micro extrusion die line, and then reused; (E) conveying the dried fine round powdery polycarbonate or prepolymer thereof to a solid state polymerization apparatus; and (F) performing a solid state polymerization to continuously separate and discharge the conveyed fine round powdery polycarbonate or the prepolymer thereof, using a solid state polymerization apparatus, based on the molecular weight thereof, wherein the steps (A) to (F) are performed via a continuous single process.