METHOD OF PRODUCING POLYOLEFIN FILM COMPOSITION AND FILMS OBTAINED USING SAID METHOD Russian patent published in 2020 - IPC C08F210/16 C08J5/18 C08F2/18 C08F2/34 C08L23/08 

FIELD: chemistry.

SUBSTANCE: method includes steps of: (i) copolymerising ethylene and an alpha-olefin comonomer in a first polymerisation step in the presence of a Ziegler-Natta polymerisation catalyst deposited on silicon dioxide, to obtain a first ethylene homo- or copolymer (PE1) having density of 940 to 980 kg/m³ and a melt flow index MFR₂ of 400 to 1000 g/10 min; (ii) copolymerising ethylene and an alpha-olefin comonomer at a second polymerisation step in the presence of a first ethylene copolymer to obtain a first ethylene polymer mixture (PES1) containing a first ethylene copolymer and a second ethylene copolymer (PE2), wherein said first ethylene polymer mixture has density of 940 to 980 kg/m³ and a melt flow index MFR₂ of 150 to 800 g/10 min, where MFR₂ of first ethylene copolymer (PE1) is higher than that of first ethylene polymer mixture (PES1), and (iii) copolymerisation of ethylene and the alpha-olefin comonomer at a third polymerisation step in the presence of a first ethylene polymer mixture to obtain a second ethylene polymer mixture (PES2) containing a first ethylene polymer mixture and a third ethylene copolymer, said second ethylene polymer mixture has density from 915 to 925 kg/m³ and a melt flow index MFR₅ of from 0.3 to 5 g/10 min.

EFFECT: present invention relates to a method of producing a multimodal ethylene polymer composition suitable for making films by blow moulding.

14 cl, 2 tbl