Abstract: 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.

Abstract: 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.

Abstract: A continuous process for the preparation of a thermoplastic molding composition is disclosed. Accordingly a first stream containing a molten polymer and at least one additive is introduced into a second extruded stream that contains a molten polymer to produce a combined stream. The temperature of the first stream that is below that of the second stream. The additive is in either liquid form, in solution or in dispersion.

Abstract: Evaporator apparatus (1) for the treatment of viscous media comprised of at least a feed chamber (2) having a perforated tray (3), a tube-bundle heat exchanger (4) connected thereto having perpendicularly arranged tubes (8) and a devolatilization chamber (5) connected thereto, a discharge unit (6) for the product and a vapor take-off (7) for removing volatile components, the tubes (8) of the heat exchanger (4) having a rectangular cross section over the greater part of their length.

Abstract: Mixer comprising a housing having filling and emptying openings, two corotating stirrers and drivers for the stirrers, one of the stirrers being arranged centrally in the housing and having at least a drive shaft and at least one transverse beam fitted to the drive shaft and at least one stirring arm fitted at their ends to the transverse beam.

Abstract: A process for concentrating polymers by evaporation is disclosed. The process entails (i) obtaining a mixture containing a polymer and volatile component, the volatile components being present in the mixture at an amount less than 20 wt. % relative to the weight of the mixture, and (ii) introducing the mixture in a downward direction under pressure through a plurality of nozzles arranged vertically and next to one another into a degassing container to form an extrudate. The volatile component contains at least one of residual monomers, oligomers and solvents, and the throughput of the mixture per nozzle is 0.3 to 2 kg/h. The vapor pressure of the volatile component of the extrudate is more than 2.5 bar, and the absolute pressure in the degassing container is 50 to 5000 Pa. The polymer prepared by the process is characterized in that it contains volatile components in an amount of less than 300 ppm.

Abstract: A strand devolatilizer that includes a degassing container, a product inlet, a product distributor, a product outlet and a vapor outlet is disclosed. The product distributor is in the form of a tube distributor with at least one distributor tube (1) and a plurality of die tubes (2) arranged in parallel, each containing a plurality of apertures (15) in the tube wall. The die tubes (2) are preferably arranged in several planes one above the other and staggered laterally relative to one another.

Abstract: 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.

Abstract: A combination static mixer and heat exchanger having heat exchanger tubes (1) which are provided over their circumference with fins (2a, 2b) which have a static mixing effect.

Abstract: 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.

Abstract: 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 fibres which are produced from these moulding compositions.

Abstract: 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.

Abstract: A process of evaporating a viscous polymer solution is described. The process includes: (a) providing a viscous polymer solution including at least 30 wt. % of solvents and monomers; (b) introducing the viscous polymer solution into a heated helix (5), the heated helix having a vapor exit velocity of 200 to 300 m/s, (a film flow including a two-phase mixture of polymer melt, and solvent vapors and monomer vapors being formed within the helix); (c) forwarding the film flow from helix (5) into a heated vapor separator (6); (d) expanding the two-phase mixture of polymer melt, and solvent vapors and monomer vapors of the film flow within vapor separator (6) at an absolute pressure of 10 mbar to 800 mbar, (a bottom product including a concentrated melt of the polymer is formed within the vapor separator); and (e) withdrawing the bottom product from vapor separator (6).

Abstract: An apparatus for carrying out mass transfer processes with high-viscosity liquids is described, particularly for boiling down and/or devolatilizing polymer melts, comprising at least a vertically arranged vessel (1) having a feeder means (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, characterized in that 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.

Abstract: A heatable and coolable static mixer comprising at least two adjacently arranged layers of bars, wherein the bars of neighboring layers cross one another and are interconnected at the crossing points and wherein the layers of bars have heat transfer ducts passing through them at the crossing points.

Abstract: Static mixer module, consisting of a disc which is provided with a multiplicity of orifices (6) and is structured on its front side and on its rear side by means of channels (4, 5), and in which the orifices (6) are made in the flanks (8) of the inlet channels (4) and open into the flanks (9) of the mixing channels (5). Furthermore, a mixer arrangement is described, which consists of at least two static mixer elements arranged one behind the other, at least one mixer element being a disc-shaped static mixer module. The mixer module and the mixer arrangement are used in pipelines and housings through which a flow passes.

Abstract: This invention relates to a process for the production of polycarbonate agglomerate of high bulk density from polycarbonate solutions, in which the organic solvent is stripped from a solution of polycarbonate by means of steam, and which is characterised in that the resulting suspension of polycarbonate particles, condensed water and water- and solvent vapor is fed in a tube or tubular heat exchanger to a separator which is partially filled with water and which is under elevated pressure. The polycarbonate agglomerates are discharged, together with part of the water, via a pressure lock at the bottom of the separator.

Abstract: The present invention provides a process for the isolation of partially crystalline polycarbonate powder or oligocarbonate powder from solutions thereof, in which process the organic solvent of a polycarbonate solution is vaporized in a heat exchanger, optionally with incorporation of steam, or in a holding tube with incorporation of steam and the pasty mixture of concentrated solution, solvent vapor and optionally water is separated in a separator. In this process, the solvent vapor is condensed in a heat exchanger downstream from the separator. The solvent is vaporized in the heat exchanger by indirect input of heat through the heat exchanger walls and vaporization may be promoted by preheating the polycarbonate or oligocarbonate solution in an upstream heat exchanger or by introducing steam or both.

Abstract: The invention relates to a process for drying polymeric powders and polymeric agglomerates, in particular thermoplastic aromatic polycarbonate or other thermoplastic polymers such as, for example, acrylonitrile-butadiene-styrene copolymer, in the melt, whereby thermoplastic polymeric powders or polymeric agglomerates containing water or solvent or both are freed from adhering moisture and contained solvent, accompanied by melting, in an apparatus provided with rotating baffles for cleaning the walls of the apparatus and for distribution and transport of the material being dried, by heat input through the walls or through the rotating baffles or both as well as by heat input as a result of shearing action. The process of drying and that of melting for the subsequent granulation are thereby combined.

Abstract: The invention relates to a two-step melt process for the production of thermoplastic, solvent-free, low-branching polycarbonates with low --OH terminal group content using a self-cleaning high-viscosity reactor.