MULTILAYER FILM WITH IMPROVED PROPERTIES Russian patent published in 2023 - IPC B32B27/06 B32B27/32 B29C48/08 C08L23/10 C08L23/12 C08L23/16 

FIELD: blown multilayer film.

SUBSTANCE: blown multilayer film includes at least two layers (A) and (B) and optionally one middle layer (C) located between layers (A) and (B). Layer (A) includes a heterophasic propylene copolymer (HECO) prepared in presence of a Ziegler-Natta catalyst. Layer (B) includes a propylene-based statistical copolymer (SCP) produced in presence of a metallocene catalyst. HECO in layer A includes: a) 75.0-95.0 wt.% polypropylene matrix (PP-M), having a MFI₂ equal to 0.8-10.0 g/10 min, which is a homopolymer or copolymer, wherein the alpha-olefin comonomer content is less than 2.0 wt.%; b) 5.0-25.0 wt.% elastomeric propylene-ethylene copolymer (PEC) dispersed in the specified matrix (PP-M); c) 0.0-0.5 wt.% one or more alpha-nucleating agents (NA). HECO has: (i) MFI₂ equal to 0.3-5.0 g/10 min; (ii) melting point equal to 160-170°C; (iii) a cold xylene soluble (CXS) fraction equal to 5.0-25.0 wt.%, based on the total weight of HECO; where the CXS fraction has an intrinsic viscosity (IV) equal to 0.8-2.8 dl/g, ethylene content equal to 10.0-45.0 wt.%; (iv) a total ethylene content of 1.0-10.0% by weight. The SCP in layer B is characterized in that it: (i) includes alpha-olefin comonomers selected from ethylene and/or 1-butene in a total amount of 2.0-8.0 wt.%; (ii) has a melting point of 115-140°C. The SCP is obtained in presence of a metallocene catalyst. The middle layer (C) includes either Ziegler-Natta-catalysed HECO or metallocene-catalyzed SCP. Blown multilayer film is used to produce flexible packaging for medical or pharmaceutical applications.

EFFECT: development of a blown multilayer film that has excellent sealing characteristics in combination with good optical parameters and has a high tensile modulus and high tear resistance.

15 cl, 6 tbl, 4 ex