Process for thermal separation of a solution consisting of thermoplastic polymer and solvent

摘要

A process for thermal separation of a solution comprised of a thermoplastic polymer and a solvent involves heating a solvent under pressure above a critical point of the solvent; decompressing the heated solvent in a first vessel, such that a polymer-rich and a low-polymer phase form; and supplying the polymer-rich phase to a second vessel. In embodiments, on entry into the second vessel, a pressure jump occurs, the pressure jump leading to a thermal flash in the second vessel such that a polymer part of the polymer-rich phase rises to at least 70%, and a resulting polymer-rich solution is provided.

主权项

1. A process for thermal separation of a solution consisting of thermoplastic polymer and solvent, whereby the solution is heated under pressure to above the critical point of the solvent and thereafter flashed inside a vessel such that a polymer-rich phase and a low-polymer phase form, wherein the polymer-rich phase is supplied to a second vessel, wherein
a) a pressure jump on entry into the second vessel leads to a thermal flash in the second vessel, the polymer part of the heavy phase rising to at least 70%, especially more than 80%; and b) the resulting polymer-rich solution is supplied—especially distributed over at least a portion of the length of a stirrer shaft—which is within the same vessel space and which heats the polymer composition by mechanical kneading energy with the effect that the polymer content rises to >70%, particularly >90%; and wherein c) a flash container is replaced by a mixer; d) the flashed solution or suspension is distributed on the hot bed over the length of the kneader and kneaded therein, which corresponds to a reconversion; e) which is implemented via one or a plurality of feed locations; f) a product space is operated at excess pressure similarly to the flash container, wherein g) a feed temperature is selected such that a product does not solidify inside the degasser, and whereby there is no granulation of the product, and wherein h) a flash kneader is used.