PROPYLENE COMPOSITION COMBINING A LOW START TEMPERATURE OF WELDING, A LOW TURBIDITY, A LOW CONTENT OF HEXANE SOLUBLE SUBSTANCES, IMPROVED TEAR RESISTANCE AND HIGH MELTING POINT Russian patent published in 2018 - IPC C08L23/12 C08F210/06 

FIELD: chemistry.

SUBSTANCE: invention relates to polypropylene composition, its preparation and use. Composition is a binary mixture comprising two fractions of the propylene polymer. First fraction is a copolymer of propylene and hexene, with a comonomer content of 0.5 to 2.5 % by weight, second fraction is a propylene terpolymer containing a hexene comonomer in an amount of 4.0 to 10.0 wt% and an ethylene comonomer in an amount of 0.1 to 1.0 wt%. Ratio of hexene content of the second polymer fraction to its content in the first polymer fraction is 2.5 to 8.0. Ratio of the total amount of hexane of the composition to the amount of hexene in the first polymer fraction is from 1.5 to 4.0. Composition is characterized by the melt flow rate MFR₂ (230 °C) from 2.0 to 15.0 g/10 min, melting point T_m from 128 °C to 145 °C, the crystallization temperature T_c from 82 °C to 110 °C and the content of substances soluble in hexane not more than 1.0 wt. %. Amount of the fraction soluble in cold xylene (XCS) is in the range of 10 to 40 % by weight.

EFFECT: composition according to the invention has a low fraction content, a wide heat sealing window at a sufficiently low temperature for the initiation of thermal welding (SIT), and also good optical properties such as low turbidity.

9 cl, 5 tbl