GAS-PHASE METHOD OF PRODUCING HETEROPHASE PROPYLENE COPOLYMERS Russian patent published in 2012 - IPC C08L23/10 C08F297/08 C08F210/06 

FIELD: chemistry.

SUBSTANCE: polymerisation method is realised in two or more series-connected gas-phase reactors in the presence of a polymerisation catalyst containing a catalyst component based on a titanium compound, deposited on a magnesium halide. The method involves a step A) for bringing the catalyst component into contact with an organoaluminium compound, possibly an external donor compound, possibly in the presence of propylene at temperature from 5°C to 30°C, with molar ratio of propylene to the catalyst component equal ranging from 0 to 2.0. Step B) follows, where the catalyst from step A) undergoes prepolymerisation with propylene, possibly in the presence of an inert hydrocarbon solvent. Further, propylene from step C) undergoes polymerisation possibly with another α-olefin comonomer in amount of less than 15 wt % to obtain a semicrystalline polymer component and subsequent copolymerisation at step D) of two or more C₂-C₁₀ α-olefin comonomers to obtain one or more olefin copolymers, having solubility in xylene higher than 15 wt %. During polymerisation, the packed density of the semicrystalline polymer component from step C) is kept lower than 0.40 g/cm³ by selecting working conditions at step A), such as temperature and/or weight ratio of propylene to the catalyst component.

EFFECT: obtained propylene copolymers are suitable for making component parts and have a wide range of useful properties such as impact resistance, permeability, lustre, hardness and shrinkage.

1 dwg, 3 tbl, 6 ex