Continuous post-condensation of plastic granules to increase viscosity involves continuous agitation of heated granules under vacuum during passage of a reactor

摘要

Granules are conveyed from storage containers(3,4) into a reactor vessel(1) where they are subjected to continuous agitation as they pass through. Granules are heated under vacuum at least during passage through the reactor. On leaving the reactor vessel granules flow into one or more product holding tanks(13). Granules are mixed and/or conveyed continuously through the reactor vessel(1) either by a coil(2) or by movement through separate sectors of the reactor. The reactor vessel rotates either continuously or in steps. Heat transfer fluid may be passed through a twin-walled coil. Storage containers(3,4) and/or product holding tank(13) are also under vacuum and either heated or cooled. Nitrogen is passed through a storage container when vacuum pressure is increased to atmospheric. A heating system(6) for the reactor vessel comprises a heat transfer fluid(17) which flows through a double skin jacket around the reactor vessel. Different temperatures can be produced in sections along the reactor length. A heated bunker(8) between the conical outlet from the reactor and product holding tank(13) is connected to a vacuum source(10) and a condenser(11). Decomposition products produced during post-condensation are condensed under vacuum and may be further processed. All product holding tanks are connected by a common pipe to the reactor vessel. AN Independent claim is included for the process equipment which comprises a cylindrical, drum-shaped reactor vessel(1) with an end wall(20) rotating around a central axis.