Mixed polyolefin separation used for low density polyethylene and high density polyethylene in waste involves using lower alkane as solvent and different lower alkane as separation aid

摘要

Separation of mixed polyolefins by liquid-liquid separation comprises using an alkane with 4-16, preferably 5-12, especially 6 C atoms as the solvent in which the polyolefins are dissolved and where solvent contains a phase-forming aid comprising a branched polyolefin based on a 3-8 (3-4) C alkane. The temperature range used has an upper limit of 0.86 of the reduced temperature (Tr) of the pure solvent, the upper phase formed contains the aid and any branched polyolefin and the lower phase contains no branched polyolefin and below 10 wt.% of the aid. The aid is used at 0.3-10 times the amount of the branched polyolefin.