Bayer Aktiengesellschaft

Other

J&uuml;rgen Heuser

Christian Kords

Thomas Elsner

Klemens Kohlgr&uuml;ber

Hermann Kauth

Steffen K&uuml;hling

Clemens Casper

Gabriel Denecker

Domien Sluyts

Werner Verhoeven

Paul Viroux

J&ouml;rgen Weinschenck

Antonio Ortiz

Richard Baxendell

Lora Rand

An apparatus for degassing plastic materials, e.g., high molecular weight polycarbonate solutions, is described. The apparatus includes a double-shaft extruder having a length-to-diameter ratio of less than or equal to 40, which comprises: (i) two co-rotating and meshing shafts; (ii) an intake opening; and (iii) upstream and downstream portions relative to the intake opening. The shafts of the extruder are designed with a double lead in a degassing zone, and with a triple lead in a pressure build-up zone. Each of the degassing and the pressure build-up zones are down-stream from the intake opening, and the pressure build-up zone is further down-stream than the degassing zone. Also described is a process for degassing plastic materials, which involves providing the described double-shaft co-rotating extruder, into which plastic material is fed, processed and degassed. Entraining agents, such as nitrogen, and other processing additives may be introduced into an extruder during the process of the present invention.

Device and method for degassing plastics

A process for preparing an emulsion is disclosed. The process entails mixing an aqueous mineral acid that contains phosphorous in an organic solvent, the mixing being continuous and with the degree of intensity sufficient to form a homogeneous emulsion. The emulsion prepared by the process is useful in the process of preparing polycarbonate by the interfacial process. Accordingly the washed organic polycarbonate that has been washed without the use of a phosphorous containing mineral acid solution is mixed with the novel emulsion. The resulting polycarbonate is characterized by its improved thermal stability.

Process for the preparation of stabilized polycarbonate

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 ( ) and a plurality of die tubes ( ) arranged in parallel, each containing a plurality of apertures ( ) in the tube wall. The die tubes ( ) are preferably arranged in several planes one above the other and staggered laterally relative to one another.

Strand evaporator

Nitrate-containing (contaminated) solutions are reduced with SO gas in the presence of an at least equimolar amount of NH or ammonium salt.

Process for the reduction of concentration of nitrates and/or nitrogen-containing compounds by means of SO2

A process for producing polymer pellets is disclosed. The process that is particular suitable for making polycarbonate pellets entails extruding a polymer melt, cooling the extrudate by contacting it with a cooling fluid and pelletizing the solidified polymer. The process is characterized in that the cooling fluid has a solids particle content of at most 10 ppm.

High-purity polymer granules and method for the production thereof

A device and process for the removal of volatile constituents from polymers is disclosed. The device entails a container having an inlet for a polymer solution, an outlet for the volatile components, an outflow for the polymer from which the volatile components have been removed and a heat exchanger. The heat exchanger is characterized in that it contains a plurality of specially structured channels.

Device and method for removing volatile components from polymer solutions

The present invention provides a polycarbonate having a low particle content, a process for producing high-purity polycarbonate and polycarbonate of maximum purity and molded products made from such polycarbonate.

Method for the production of highly pure polycarbonate and ultrapure polycarbonate

A process for the production of polycarbonate is disclosed. The process, representing an improvement over the known interfacial polycondensation process entails introducing into the loop of a circulating reactor that additionally contains, a residence tank, an optional mixer, a pump, and a heat exchanger (i) an organic phase that contains a solvent for polycarbonate and phosgene and (ii) an aqueous phase that contains an aqueous lye solution, a dihydroxy compound and an optional monophenol to form an emulsion. Maintaining specified temperature and process conditions results in polycarbonate resin having good properties and in waste water that are characterized by their purity.

Process for producing polycarbonates

A process for preparing a vacuole-free polymer is disclosed. Extruded polymer resin is cooled at a rate of less than 50&deg; C./sec. to a temperature that is 1 to 20&deg; C. above the glass transition temperature of the polymer resin and the resin is then cut.

Vacuole-free polymer granulates

Described is a multi-stage, continuous process for evaporating and concentrating feed polymer solutions. In a first stage (a) of the process, the feed polymer solution is concentrated by passing it through one of (i) a combination of a tubular heat exchanger with one of a thin-film evaporator and a coiled tube evaporator, and (ii) a tubular heat exchanger. Each evaporator of (i) having a downstream separator. In a further stage (b), the intermediate polymer solution of the first stage is further concentrated and degassed to form a product polymer in a tubular heat exchanger having a downstream separator. The tubular heat exchanger of the further stage has an inside diameter of from 5 to 30 mm, and a length of from 0.5 to 4 m, and the throughput per heat exchanger tube being from 5 to 30 kg/h, based on the polymer. An entrainer is introduced into a delivery device located downstream from the separator of further stage (b). The product concentrated/degassed polymer of further stage (b) is then isolated and optionally granulated. Also described is an apparatus for evaporating and concentrating feed polymer solutions.

Method and device for evaporating polymer solutions of thermoplastic polymers, and a polycarbonate which can be obtained by evaporation

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.

Method for evaporating polymer solutions of thermoplastic polymers

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 ( ), 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 ( ) into a heated vapor separator ( ); (d) expanding the two-phase mixture of polymer melt, and solvent vapors and monomer vapors of the film flow within vapor separator ( ) 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 ( ). Each of the helix ( ) and vapor separator ( ) have a separate heating device, and each of heating device independently provides a temperature that is above the softening point of the polymer.

Method for isolating polymers from solutions

A method for removing volatile components from polymer solutions is disclosed. The method, yielding products having low content of residual volatile components and causing no thermal damage to the polymer, entails using apparatuses in which surfaces which come into contact with the product are made from materials which are low in iron content.

Methods for removing volatile components from polymer solutions

The production of polycarbonate by the phase boundary method is disclosed. In accordance with the inventive process, a solution that contains polycarbonate is repeatedly washed with a washing liquid and the washing liquid is separated from the solution that contains the polycarbonate by separating elements and the solvent is then evaporated. The process is characterized in that the organic solution that contains the polycarbonate and the washing liquid are separated from each other after the first washing stage in a coalescer that contains hydrophilic packing.

Growing community of inventors

Krefeld, Germany

Jürgen Heuser

Growing community of inventors

Krefeld, Germany

J&uuml;rgen Heuser

Jürgen Heuser