METHOD FOR FINAL TREATMENT OF POLYOLEFINS Russian patent published in 2012 - IPC C08F6/00 C08F10/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a method for final treatment of polyolefins obtained via gas-phase catalytic polymerisation of one or more α-olefins in the presence of a diluent for the polymerisation mixture. The diluent is selected from C₃-C₅-alkanes. Polyolefin granules fed into the gas-phase reactor undergo treatment at a first degassing step which is carried out in a first reservoir. Said polyolefin is brought into contact with a gas stream in counter-flow conditions, said gas stream containing at least 85 mol % washing reagent selected from C₃-C₅-alkane. The gas stream is continuously extracted from the monomer regeneration section of the polymerisation apparatus. The granules then undergo treatment at a second degassing step which is carried out in a second reservoir, where said polyolefin is brought into contact with water vapour in counter-flow conditions. The amount of water vapour ranges from 10 to 200 kg per 1000 kg polyolefin.

EFFECT: efficient removal of oligomers and heavy hydrocarbons from polyolefin granules coming out of a gas-phase polymerisation apparatus and responsible for causing smells.

19 cl, 1 dwg, 1 tbl, 4 ex