SOFT AND TRANSPARENT COPOLYMERS OF PROPYLENE Russian patent published in 2019 - IPC C08L23/14 C08L23/16 C08L23/08 C08F2/00 C08J5/18 

FIELD: manufacturing technology.

SUBSTANCE: invention relates to a polypropylene composition (C) which is intended for making a film, a film made from said composition, as well as a method of producing a polypropylene composition (C). Polypropylene composition contains a heterophase propylene copolymer (RAHECO) and plastomer (PL). Heterophase propylene copolymer (RAHECO) contains a matrix (M) representing a disordered propylene copolymer (R-PP) and an elastomeric propylene copolymer (E) dispersed in said matrix (M). Comonomers of random copolymer of propylene (R-PP) and elastomeric copolymer of propylene (E) are ethylene and/or C₄-C₈ olefins. Plastomer (PL) is a copolymer of ethylene and at least one C₄-C₂₀ α-olefin with density of less than 0.900 g/cm³ and melt flow rate MFR₂ (190 °C/2.16 kg) from 10.0 to 40 g/10 minutes. Method of producing polypropylene composition (C) involves first polymerisation of propylene and ethylene and/or C₄-C₈ α-olefin in first reactor (R1). First fraction of a random copolymer of propylene (R-PP1) is obtained, which is transferred to a second reactor (R2). Further, polymerisation is carried out in the presence of a first fraction of a random copolymer of propylene (R-PP1) and ethylene and/or C₄-C₈ α-olefin. Second fraction of random copolymer of propylene (R-PP2) is obtained. First fraction of the random propylene copolymer (R-PP1) and the second fraction of the random propylene copolymer (R-PP2) form a random copolymer of propylene (R-PP), which is transferred to a third reactor (R3). After that, polymerisation is carried out in the presence of random copolymer of propylene (R-PP) and/or C₄-C₈ α-olefin. Third polymer fraction is obtained, which is an elastomeric copolymer (E). Propylene copolymer (R-PP) and the propylene elastomeric copolymer (E) form a heterophase propylene copolymer (RAHECO). Then a heterophase propylene copolymer (RAHECO) is mixed in the melt with a plastomer (PL). Film is made from said polypropylene composition.

EFFECT: invention enables to obtain a polypropylene composition having improved optical and mechanical properties.

13 cl, 1 dwg, 2 tbl, 3 ex