MOULDING COMPOSITION Russian patent published in 2014 - IPC C08L23/04 C08L23/08 

FIELD: chemistry.

SUBSTANCE: invention relates to a polyethylene moulding composition intended for making pipes, conduits and cables, and a method of producing said composition. The composition has a multimodal molecular-weight distribution, density in the range of 920 to 960 kg/m³, melt flow index MFI_190/2 in the range of 0.05 to 10 g/10 min and Shore hardness D, measured according to ASTM D2240-05 (15 s), of at least 56.0. The composition contains at least three ethylene polymer fractions having different molecular weight. Each of the fractions A, B and C is an ethylene homopolymer or a copolymer of ethylene with at least one C₃-C₁₀ comonomer. In the composition, one of the fractions A, B and C is an ethylene homopolymer and at least one of the other fractions is an ethylene copolymer with content of said C₃-C₁₀ comonomer of 1-15 wt %. Fraction A has weight-average molecular weight M_w in the range of 15 to 40 kg/mol, fraction B - in the range of 70 to 200 kg/mol and fraction C - in the range of 220 to 400 kg/mol.

EFFECT: obtained polyethylene moulding composition has excellent mechanical properties, hardness and wear resistance, and also has high impact resistance and slow crack growth.

13 cl, 6 dwg, 6 tbl