NOVEL TRIMODAL POLYETHYLENE FOR USE IN BLOW MOLDING Russian patent published in 2016 - IPC B29C49/00 C08F210/16 C08L23/06 C08L23/08 B29D22/00 

FIELD: chemical industry.

SUBSTANCE: invention relates to trimodal polyethylene suitable for blow moulding articles larger than 10 l. Trimodal polyethylene has density from 0.950 to 0.958 g/cm³, flow melt index (HLMI) according to ASTM D 1238, at 190 °C and 21.6 kg, from 2 to 7 g/10 min and value of nondimensional Hostalene index of trimodal polyethylene from 6 to 18. Polyethylene consists essentially of three weight fractions A, B and C, wherein fraction A with a low molecular weight is a homopolymer having a melt index (HLMI) of 18 to 30 g/10 min, and fractions B and C with medium and high molecular weight, respectively, are copolymers of ethylene and 1-butene comonomers. Wherein mixture of polymers A and B has a melt index (HLMI) from 8 to 14 g/10 min and a mixture of polymers A, B and C has a melt index (HLMI) from 3 to 6 g/10 min. Trimodal polyethylene is prepared by stepped polymerisation in presence of a solid Ziegler catalyst component and preferably in presence of a trialkylaluminium as a cocatalyst component.

EFFECT: polyethylene according to invention has good processability, and a product after blow molding has improved stability of dimensions.

19 cl, 3 tbl, 3 ex