Bayer Aktiengesellschaft

Other

Gunther Weymans

Dieter Freitag

Uwe Westeppe

Claus H Wulff

Knud Reuter

Rolf Dhein

Karsten-Josef Idel

Jurgen Kirsch

Jurgen Heuser

Wolfgang Herrig

Ulrich R Grigo

Werner Waldenrath

Carl Casser

Lutz Schrader

Franz Ferdinand Rhiel

Erich Meier

Karl-Herbert Fritsch

Rolf Treckmann

Hanns-Ingolf Paul

Uwe Hucks

Reinhard Schomacker

Jurgen Kadelka

Klaus Elgeti

Bernd Pittel

Gerold Muller

Wolfgang Jilge

Manfred Schmidt

Ludwig Bottenbruch

Wolfgang Alewelt

Leo Morbitzer

Volker Eckhardt

Hermann Kauth

Klaus D Berg

Rolf Bachmann

Ernst-Ulrich Dorf

Wolfgang Russeler

Zoltan Kricsfalussy

Peter Horlacher

Heinrich Steude

Kurt Weirauch

Paul J Mayska

Alfred Jung

Konrad Hable

Said Mahiout

Lothar Lang

The invention relates to a process for the production of polycarbonates by the two-phase interfacial method in which deviations between measured and estimated variables are continuously minimized by means of a suitably selected observer or filter system on the basis of a process model with an empirical Mark-Houwink relation adapted to the process. The variables estimated by the observer/filter are converted into control variables which are used to set input streams of the production process. Product quality is kept constant, changes in load or set values are quickly intercepted and even disturbances not readily accessible to measurement are taken into account by the process control.

Process for the production of polycarbonate of constant viscosity

A method of controlling concentrations in process technology operations--preferentially in thermal separation technology--using a non-linear, pressure-compensated temperature as control signal. The method can be used flexibly within a wide operating range.

Method of controlling the concentrations of a multicomponent mixture

A method of controlling a heat exchanger wherein the enthalpy flow into the heat exchanger serves as a correcting variable. The robust and versatile control method is particularly suitable for use in endothermic reactions and for distillation.

Method of controlling heat exchangers using enthalpy flow as the

The invention relates to ultrafine suspensions of bisphenol, sodium hydroxide and water for the production of polycarbonates by the two-phase interfacial process. According to the invention, these suspensions are prepared by cooling bisphenolate concentrations near the solubility limit in aqueous sodium hydroxide with intensive mixing at relatively high temperatures and precipitating bisphenolate or more bisphenolate in the form of fine droplets during the cooling process. The ultrafine suspensions provide for a high volume/time yield in the interfacial reaction.

Production of ultrafine suspensions of bisphenol, sodium hydroxide and

A continuous process for the removal of electrolytes and catalysts from organic polycarbonate solutions is disclosed. Accordingly, a solution obtained in the course of the two-phase interfacial reaction for the preparation of polycarbonate, containing thermoplastic aromatic polycarbonate and an organic solvent and up to 10 parts by weight water as well as residues of chain terminators, branching agents and diphenols is washed with water and/or hydrochloric acid through a cascading train of centrifuges. The resulting polycarbonate resin is characteristically of extremely low iron content.

Washing of polycarbonates with cascading train of centrifuges

A process for the continuous production of a thermoplastic aromatic polycarbonate is disclosed. Accordingly, in a reactor system which includes a tube reactor and a tank equipped with a stirrer, there are reacted a preheated dialkali diphenolate aqueous solution with gaseous phosgene in CH.sub.2 Cl.sub.2 and/or in chlorobenzene solution containing excess phosgene, in a mixer to form a mixed emulsion. The emulsion is then transported at least partly against the force of gravity into the tube reactor to facilitate a polycondensation reaction and in which after a residence time of at least 10 seconds and without dissipation of the heat of reaction there is added a chain terminator. The heat of reaction is dissipated in said tank and aqueous sodium hydroxide and catalyst are added to complete the reaction. The process according to the invention leads to high yields of phosgene.

Process for the production of polycarbonate

According to the invention, a special process for isolating polycarbonate from methylene chloride at temperatures of 30.degree. to 80.degree. C. in the form of a powder with residual solvent contents below 5% by weight is started up as a continuous process by starting up in a two-component nozzle, in which CO.sub.2 -containing fluid and the polymer solution are continuously combined, with a large excess of CO.sub.2 and then allowing the polycarbonate/methylene chloride/CO.sub.2 fluid system to pass through the gel-forming range of the polycarbonate/methylene chloride/CO.sub.2 phase diagram with continuous reduction of the CO.sub.2 throughput to a ratio of CO.sub.2 to organic solution of 4:1 to 2:1. The process started up in this way has a particularly long useful life.

Isolation of polycarbonate with carbon dioxide

A process for isolating a poly(ester)carbonate resin from its methylene chloride solution is disclosed. The process entails combining a solution which contains 5 to 30% by weight resin with carbon dioxide fluid in a two-component nozzle under pressures of 90 to 180 bar and at temperatures of 50.degree. to 75.degree. C., while maintaining in said the two-component nozzle a back-pressure of 85 to 150 bar, and introducing the resin into a separation vessel with retention of dust particles. Importantly, the relative quantities of carbon dioxide fluid and polymer solution used in the two-component nozzle are between 10 and 3 parts carbon dioxide fluid per one part of polymer solution, and the carbon dioxide fluid contains 10 to 1000 ppm methylene chloride. The process avoids blockage of said nozzle.

Isolation of poly(ester)carbonates from methylene chloride using carbon

A process for the separation of multicomponent systems containing intermediate boiling substances in separating separating columns with side discharge, the temperatures T.sub.u and T.sub.o above and below the side discharge are measured on the column or inside the column and the temperature difference T.sub.u -T.sub.o is used for controlling the side discharge. The control is carried out by constantly controlling one of the two temperatures T.sub.u or T.sub.o by the output of the evaporator or the discharge from the sump or the reflux or the removal of distillate or the reflux ratio.

Process for the separation of multicomponent systems containing

An improvement to the continuous process for the production of polycarbonates by interphase polycondensation is described. Accordingly, the organic phase and the aqueous phase are combined in a tube, forming chlorocarbonic acid ester and further alkali hydroxide is added at, or shortly after, the maximum concentration of said ester is reached. The resulting emulsion is then changed to an oil-in-water emulsion which is then separated and worked up in known manner.

Continuous production of polycarbonates

A process for isolating polymers from their solvents by addition of fluids containing carbon dioxide at temperatures of 30.degree. to 280.degree. C. and under pressures of 1 to 1,000 bar is disclosed. The process is characterized in that the concentration of the polymers in their solvents is between 5% and 80% by weight and the fluid containing carbon dioxide consists of at least 50% by weight carbon dioxide.

Process for isolating polymers from their solvents using liquids

Dihydroxydiphenyl cycloalkanes corresponding to the formula ##STR1## in which R.sup.1 and R.sup.2 independently of one another represent hydrogen, halogen, C.sub.1 -C.sub.8 alkyl, C.sub.5 -C.sub.6 cycloalkyl, C.sub.6 -C.sub.10 aryl and C.sub.7 -C.sub.12 aralkyl,

Polycarbonate from dihydroxydiphenyl cycloalkane

A continuous process for the isolation of polycarbonates from a solution of polycarbonate in methylene chloride at temperatures of 30.degree. to 80.degree. C. is disclosed. The process which yields polycarbonate in powder form having residual solvent content of less than 5% by weight, is characterized in that it entails the following steps:

Process for isolating polycarbonates with CO.sub.2 under pressure

Aromatic polyether sulfones based on 5 to 90 mol-%, based on total bisphenols, of special dihydroxydiphenyl cycloalkanes and 10 to 95 mol-% based on the bisphenols of specific phthaleins, a process for their production and their use as molding compounds.

Aromatic copolyether sulfones

The new aromatic ether imides corresponding to the following formula ##STR1## may be used for the production of plastics which in turn may be worked up into moulded articles, films, sheet products and filaments. The plastics produced from the new aromatic ether imides are distinguished by their exceptional dimensional stability under heat.

Aromatic ether imides

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Leverkusen, Germany

Gunther Weymans