POLYPROPYLENE FILM WITH IMPROVED SLIP PROPERTIES Russian patent published in 2023 - IPC C08J5/18 C08L23/12 C08K3/17 C08K3/36 C08K5/20 C08F4/659 C08F110/06 B29C48/00 B29C55/28 

FIELD: polypropylene film.

SUBSTANCE: invention relates to a method for producing a film containing a polypropylene composition showing improved coefficient of friction and optical properties. A method for producing a film is described, which includes the following steps: i) a propylene homopolymer (HPP) having a melting point (Tm) measured by differential scanning calorimetry (DSC) according to ISO 11357, in the range from 152 to 162°C, cold xylene soluble fraction (XCS) determined at 25°C according to ISO 16152, equal to or less than 1.5 wt.%, and the content of 2,1-erythro-regiodefects, determined using ¹³C-NMR spectroscopy, in the range from 0.01 to 1.00 mol.% polymerized in a multi-stage process in which a loop reactor is followed by a gas phase reactor, in the presence of a metallocene catalyst system comprising: (i') a metallocene catalyst complex of formula (I)

where Mt is Hf or Zr; each X is a sigma ligand, each R¹, identical or different, independently represents a CH₂-R⁷ group, where R⁷ represents H or a linear or branched C_1-6 alkyl group, C_{3- 8} cycloalkyl group, C_6-10 aryl group, each R² independently represents a -CH=, -CY=, -CH₂-, -CHY- or -CY₂ - group, where Y represents a C_1-10 hydrocarbyl group and where n is 2-6, each of R³ and R⁴, the same or different from each other, independently represents hydrogen, a linear or branched C₁-C₆ alkyl group, an OY group, or a C_7-20 arylalkyl, C_7-20 alkylaryl group or a C_6-20 aryl group, wherein at least one R³ per phenyl group and at least one R⁴ is not hydrogen, and optionally two adjacent R³ or R⁴ groups may be part of a ring, containing the carbon atoms of the phenyl group to which they are attached, R⁵ is a linear or branched C₁-C₆-alkyl group, C_7-20 arylalkyl group, C_7-20 alkylaryl group or C₆-C₂₀-aryl group, R⁶ represents a C(R⁸)₃ group, and R⁸ represents a linear or branched C₁-C₆ alkyl group, each R independently represents C₁-C₂₀ hydrocarbyl, C₆-C₂₀ aryl, C₇-C₂₀ arylalkyl, or C₇-C₂₀ alkylaryl, and (ii') a cocatalyst containing a group 13 metal compound, and ii) forming a polypropylene composition into a film containing 95.0-99.9 wt.% of propylene homopolymer (HPP) obtained at stage (i) together with 0.1-0.4 wt.% of a slip additive and 0.0-0.5 wt.% of an anti-block additive.

EFFECT: providing a method for producing films characterized by a low friction coefficient, low turbidity and high transparency.

11 cl, 2 tbl, 4 ex