METHODS OF MODIFYING THE MELT FLOW RATIO AND/OR SWELL OF POLYETHYLENE RESINS Russian patent published in 2019 - IPC C08F210/16 C08F10/02 C08F4/6592 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing polyethylene resins. Described is a method of modifying the melt flow ratio and swelling characteristics of polyethylene resins. Method of modifying melt flow ratio (I₂₁/I₅) and a method of modifying the swelling by weight of polyethylene resin involves feeding a catalyst system, hydrogen, ethylene and optionally a comonomer into a polymerisation reactor. Catalyst composition contains at least two different catalytic compounds containing element 15 of group and metal and at least one metallocene catalytic compound. Catalytic compounds enable to obtain polyethylene with different molecular weights at the same ratio of hydrogen to ethylene. Ratio of hydrogen to ethylene in the reactor is controlled simultaneously in range of 10–15 ppm/mol. %. Intra-reactor molar ratio of catalytic compound is 2.5–1.8 and provides constant value of flow index I₂₁ when modifying melt flow ratio (I₂₁/I₅) and is within 30 % of target value.

EFFECT: method enables to modify the melt flow ratio and/or swelling of the polyethylene resin while maintaining a substantially constant resin fluidity index.

6 cl, 2 dwg, 4 tbl, 4 ex