POLYPROPYLENE SUITABLE FOR PRODUCING BOPP FILMS, COMPOSITION CONTAINING IT, METHOD FOR ITS PRODUCTION, FILM CONTAINING IT Russian patent published in 2024 - IPC C08F110/06 C08F2/06 C08L23/12 C08J5/18 

FIELD: polypropylene industry.

SUBSTANCE: polypropylene for producing films, in particular biaxially oriented polypropylene (BOPP) films, as well as a method for producing polypropylene using suspension process in a hydrocarbon solvent. Polypropylene satisfies the following characteristics: molecular weight distribution (MWD) in the range from 4.5 to 8.5; content of the crystalline fraction with a melting point of more than 178°C, determined by the method of stepwise isothermal separation SSA, no more than 3.5%; distribution of the crystalline fraction over the thickness of the lamellas – L_w/L_n from 1.25 to 1.35; melt flow index (MFI) 230°C/2.16 kg, from 3.0 to 4.0 g/10 min. The method for producing polypropylene is carried out by polymerization in a hydrocarbon solvent and includes the use of at least three reactors. This method includes a) obtaining in the first reactor the first fraction of polypropylene with a melt flow index (MFI) 230°C/2.16 kg from 2.5 g/10 min to 2.9 g/10 min; b) obtaining in the second reactor the second fraction of polypropylene with a melt flow index (MFI) 230°C/2.16 kg from 5.5 to 10.5 g/10 min; c) transferring the first and second polypropylene fractions to a third reactor; and d) mixing the first and second polypropylene fractions in a third reactor to produce polypropylene. The structural characteristics of the claimed polypropylene make it possible to obtain BOPP films at a processing speed of more than 430 m/min without the occurrence of film breaks.

EFFECT: polypropylene obtained using this method is characterized by a set of properties that are necessary to obtain BOPP films from it with improved physical and mechanical characteristics and optical properties.

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