Basf Aktiengesellschaft

Peter Fink

Rudi W Reffert

Johann Zizlsperger

Gunter Thielen

Hans Wild

A process for removing vaporizable constituents from high-viscosity solutions or melts of thermoplastics by continuous evaporation along a heated devolatilization zone and separation of the vapor phase from the liquid phase in a downstream separating vessel. The plastic solution or melt is first heated stepwise in increments, in the devolatilization zone, while the product is in the form of thin layers from about 0.5 to 4 mm, so as to maintain a temperature difference of less than 50.degree. C. between the heat transfer medium and the plastic solution or melt until the devolatilization temperature is reached, the distribution of the solution or melt to form thin layers of product taking place while the temperature conditions still correspond to those of the feed of solution or melt, after which the vaporizable constituents are evaporated so as to form a two-phase system of vapor and melt, and the heat of evaporation absorbed is substantially returned to the product during the evaporation along the devolatilization zone. The process permits the removal of vaporizable constituents under mild conditions.

Process and apparatus for removing vaporizable constituents from viscous

A process and an apparatus for heating or cooling very viscous solutions or melts of thermoplastics in the form of thin layers. The plastic solution or melt is spread under the temperature conditions of the feed solution or melt, and the thin layers are heated stepwise so that the temperature difference between the heat transfer medium and the solution or melt is at all times less than 50.degree. C. and preferably less than 20.degree. C. Viscous solutions or melts of thermoplastics can be heated or cooled rapidly and uniformly under gentle and controlled conditions, to prepare the solutions or melts for further treatment in conventional equipment.

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Speyer, Germany

Peter Fink