Continuous manufacture of elastic polypropylene@ by polymerisation of propylene in liquid propylene

摘要

In a process for continuous manufacture of elastic polypropylenes, propylene is polymerised in liquid propylene, possibly with an ethylene comonomer, the reaction occuring in reactors (1,2) at 50-100 deg C, preferably 60-75 deg C and 25-60 bar, preferably 10-15 bar pressure. The solids content in the polymerised mixture on leaving the reactors is 5-30 Ma%, preferably 10-20 Ma% and in a subsequent thickening stage is increased to 20-50 Ma%, preferably 30-40Ma%. Thickened polymer mixture is then decompressed to 2-25 bar, preferably 10-15 bar, causing evaporation of part of the non-converted monomer and then fed direct to the feed zone of an extruder(4) in which the polymer is separated from the non-converted monomers and after addition of additives is melted, homogenised and granulated. Preferably separation of the polymers from non-converted monomers occurs in the solids conveying zone of the extruder and the non-converted monomers are fed back into the polymerisation process. Thickening of the polymerised mixture occurs in a hydrocyclone (3). Catalyst residues from the polymerisation are deactivated with water or alcohols, preferably in the twin screw extruder (4).