POLYPROPYLENE-BASED COMPOSITION HAVING LOW WELDING START TEMPERATURE AND HIGH MELTING POINT Russian patent published in 2020 - IPC C08F210/06 C08F2/00 C08J5/18 B32B27/32 

FIELD: chemistry.

SUBSTANCE: invention relates to a polypropylene composition, a method for production thereof, use of the polypropylene composition and a film. Polypropylene composition is a binary mixture containing 30 to 50 wt. % of fractions of propylene polymer FPP1 and from 70 to 50 wt. % of fractions of propylene polymer FPP2. Fraction of propylene polymer FPP1 is a copolymer of propylene, which contains propylene monomers and from 1.50 to 7.00 mol. % of comonomer, which is C₄-C₁₀ alpha-olefin. Fraction of propylene polymer FPP2 is a propylene terpolymer containing propylene monomers, from 0.30 to 3.00 mol. % of ethylene comonomer and 3.50 to 12.00 mol. % of comonomer, which is C₄-C₁₀ alpha-olefin. Polypropylene composition satisfies the following equation: Delta = Tm - LWT, where Delta ranges from 30 to 43 °C, Tm is temperature, °C, melting of propylene composition and ranges from 135 to 160 °C, LWT is temperature, °C, beginning of welding of propylene composition. Amounts of FPP1 and FPP2 are calculated in terms of total content of fractions of propylene polymers FPP1 and FPP2. Method of producing the polypropylene composition involves first polymerising propylene and one C₄-C₁₀ alpha-olefin comonomer in a first reactor which is a slurry reactor R-1. Then obtained fraction of propylene polymer FPP1 and unreacted comonomers are transported from reactor R-1 to second reactor R-2, which is first gas-phase reactor-1, GPR-1. Further, propylene, ethylene and one comonomer C₄-C₁₀ alpha-olefin are polymerised in a gas-phase reactor-1, GPR-1, in the presence of a propylene polymer fraction FPP1 and a propylene polymer fraction FPP2, which is a propylene terpolymer, is obtained. Further, a polypropylene composition is removed from the reactor. Polypropylene composition is used to produce a film or a multilayer film.

EFFECT: invention enables to obtain a composition with low welding temperature (LWT) and high melting temperature (Tm).

12 cl, 2 tbl