HIGH-DENSITY POLYETHYLENE-BASED COMPOSITIONS, METHODS FOR PRODUCTION THEREOF, ARTICLES MOULDED THEREFROM AND METHOD OF OBTAINING SAID ARTICLES Russian patent published in 2012 - IPC C08L23/08 C08F210/02 C08F255/02 

FIELD: chemistry.

SUBSTANCE: group of inventions relates to a high-density polyethylene-based bimodal composition and a method of producing said composition, as well as a bottle cap made from said composition, and a method of making said cap. The composition contains a first component which is a high-molecular weight ethylene/alpha-olefin copolymer having density ranging from 0.920 to 0.946 g/cm³ and flow melt index (I_21.6) ranging from 1 to 15 g/10 min. The composition also contains a second component which is a low-molecular weight ethylene polymer, having density ranging from 0.965 to 0.980 g/cm³ and flow melt index (I₂) ranging from 30 to 1500 g/10 min. The obtained composition has flow melt index (I₂) of at least 2 g/10 min, density ranging from 0.950 to 0.960 g/cm³ and molecular weight distribution ranging from 5 to 11. The method of producing the composition involves a step of feeding an ethylene and alpha-olefin comonomer into a first reactor and polymerisation of the ethylene and alpha-olefin comonomer in the first reactor to obtain a first component which is a high-molecular weight ethylene/alpha-olefin copolymer. The first component and additional ethylene are then fed into a second reactor and the additional ethylene is polymerised in the second reactor to obtain a second component which is a low-molecular weight ethylene polymer. The high-density polyethylene-based composition is then obtained.

EFFECT: high crack resistance and impact strength of articles made from the obtained composition.

13 cl, 7 dwg, 4 tbl, 6 ex