摘要:
A process for the isolation of polycarbonate produced by the interfacial polymerization process is disclosed. Accordingly, the process entails (a) evaporating the organic solvent from the solution that contains solvent and polycarbonate to obtain a material system that contains 90 to 99.95% polycarbonate, the percent being relative to the weight of the system, and (b) passing the material system through inlet openings of a separating vessel to obtain a plurality of streams of polycarbonate, on entry into the inlet openings said material system being supersaturated with volatile constituents to an extent of at least 1 bar and having a temperature of 250° to 340° C. and a flow rate of 0.1 to 20 kg/hour, and (c) degassing the streams in the separating vessel wherein the pressure is 0.1 to 20 mbar to effect degassing of the polycarbonate.
摘要:
The invention describes a process for the preparation of polycarbonate. The process includes (a) transesterifying at least one aromatic dihydroxyaryl compound and a diaryl carbonate in the melt in the presence of a catalyst, (b) mixing the melt obtained in step (a) with a foaming agent (c) passing the mixture at 250 to 340° C. through inlet openings of a separating vessel at a rate of 0.1 to 20 kg/hour, to obtain a plurality of streams of foamed polycarbonate and degassing the streams of foamed polycarbonate in the separating vessel wherein the pressure is 0.1 to 20 mbar.
摘要:
The invention is directed to an extruder (10), particularly for extruding a synthetic rubber product, which comprises a barrel (24), one or several extruder elements (12, 14), particularly one or several extruder screws and/or a kneader elements (14), arranged inside the barrel (24) for conveying the product, optionally an inlet port for feeding a stripping agent into the barrel (24) and an outlet port for removing volatile compounds from the product and, where applicable, the stripping agent. According to the invention a perforated die plate (26) is fixed to the barrel (24) in flow direction before the outlet port. Since the die plate (26) is not fixed to the extruder elements (12, 14) but to the barrel (24) a circumferential clearance between the die plate (26) and the barrel (24) is prevented so that no extruded material is passing the die plate (26) radially outside. Parts of the extruded material comprising a low surface area to volume ratio are prevented so that the evaporation of volatile compounds is facilitated.
摘要:
The invention relates to an apparatus and a process for devolatilizing solvent-containing polycarbonate solutions. By employing the inventive apparatus, polycarbonates with low residual values of volatile constituents are produced from solvent-containing polymer melts, which improved optical properties, especially yellowness index, with the aid of an apparatus combination of a flash devolatilizer and a vented extruder.
摘要:
The invention relates to an apparatus and a process for devolatilizing solvent-containing polycarbonate solutions. By employing the inventive apparatus, polycarbonates with low residual values of volatile constituents are produced from solvent-containing polymer melts, which improved optical properties, especially yellowness index, with the aid of an apparatus combination of a heatable tubular devolatilizer and a vented extruder.
摘要:
A continuous process for mixing polymer melts with additives, in particular polycarbonate melts with additives in liquid form, in solution or in dispersion is described. The additives are added to a main stream of polymer melt and are then mixed, preferably directly, with the main stream in a static mixer.
摘要:
Rubber-free copolymers of unsaturated monomers selected from the group comprising styrenes and vinyl cyanides are disclosed. The copolymers that contain 65 to 80 wt. %, of styrene and 20 to 35 wt. % of acrylonitrile are characterized in their low content of residual monomers and improved physical properties. Also disclosed are a process and a device for the preparation of these copolymers.
摘要:
Apparatus for carrying out mass transfer processes with high-viscosity liquids comprising a vertically arranged vessel (1) having a feeder (4) for the liquid to be treated, an outlet (7) for volatile components and an outlet (6) for the treated liquid, the feeder means (4) being equipped with a distributor element (3) having a multiplicity of orifices (8, 10) for subdividing the high-viscosity liquid to be treated into a multiplicity of individual streams, wherein essentially vertically arranged wire loops (2) are disposed in the vicinity of the orifices (8, 10), along which wire loops the high-viscosity liquid runs off under the action of gravity.
摘要:
A process for producing a polyamide or copolyamide freed from volatile constituents by removing the volatile constituents, in particular the monomers and dimers, in at least two stages from the polymer melt by using an, in particular, gaseous entrainer is described. The invention also relates to polyamide compositions made of polyamide 6 or a copolyamide with a reduced volatile constituent content, as well as moulding compositions made of the above-mentioned polyamides, and moulded articles and fibers which are produced from these moulding compositions.
摘要:
This invention relates to a multistep process for evaporating polymer solutions of thermoplastic polymers and for removing volatile constituents from thermoplastic polymers by indirect heat exchange. The invention relates in particular to a process for evaporating volatile constituents out of polymer solutions using shell-and-tube heat exchangers having a special geometry, coiled-tube evaporators and extrusion evaporators.