Biaxially oriented polypropylene-based multilayer film

A biaxially oriented polypropylene-based multilayer film comprising at least a core layer (CL), a first outer layer (OL1) and a second outer layer (OL2), wherein

• the first and the second outer layers (OL1) and (OL2) comprise
• 70.0 to 100.0 wt.-%, based on the total weight of the respective outer layer, of a metallocene catalysed ethylene-propylene-1-butene terpolymer (mC2C3C4) base resin having
• an ethylene (C2) content measured by 13C-NMR analysis (as described in the experimental part) in the range of 0.7 to 2.0 wt.-% with respect to the total weight of the mC2C3C4 base resin;
• a 1-butene (C4) content measured by 13C-NMR analysis (as described in the experimental part) in the range of 4.0 to 7.8 wt.-% with respect to the total weight of the mC2C3C4 base resin;
• a propylene (C3) content measured by 13C-NMR analysis (as described in the experimental part) in the range of 90.2 to 96.0 wt.-% with respect to the total weight of the mC2C3C4 base resin;
• wherein the units derived from ethylene, propylene and butene add up to 100 wt.-%, and
• a melt flow rate MFR2 (230° C./2.16 kg) measured according to ISO 1133 in the range from 3.0 to 10.0 g/10 min;
• a xylene cold soluble (XCS) content in the range of 2.0 to 5.0 wt.-%, determined at 25° C. according ISO 16152, based on the total weight of the mC2C3C4 base resin;
• a melting temperature Tm as determined by DSC according to ISO 11357 in the range from 120 to 129° C.;
• a crystallization temperature Tc as determined by DSC according to ISO 11357 in the range from 80 to 110° C. and
• a number of 2,1 regio-defects measured by 13C-NMR analysis (as described in the experimental part) in the range of 0.10 to 1.5 mol-% and
• wherein the mC2C3C4 base resin consists of
• (i) 30.0 to 60.0 wt.-%, based on the total weight of the mC2C3C4 base resin, of a first polymer component (TERPO-1) having
• a melt flow rate MFR2 (230° C./2.16 kg) measured according to ISO 1133 in the range from 1.0 to 10.0 g/10 min;
• an ethylene (C2) content measured by 13C-NMR analysis (as described in the experimental part) in the range of 0.7 to 1.3 wt.-% with respect to the total weight of the first polymer component (TERPO-1) and
• a 1-butene (C4) content measured by 13C-NMR analysis (as described in the experimental part) in the range of 4.0 to 6.0 wt.-% with respect to the total weight of the first polymer component (TERPO-1);
• and
• (ii) 40.0 to 70.0 wt.-% based on the total weight of the mC2C3C4 base resin, of a second polymer component (TERPO-2) having
• a melt flow rate MFR2 (230° C./2.16 kg) measured according to ISO 1133 in the range from 10.0 to 20.0 g/10 min;
• an ethylene (C2) content measured by 13C-NMR analysis (as described in the experimental part) in the range of 1.3 to 2.0 wt.-% with respect to the total weight of the second polymer component (TERPO-2) and
• a 1-butene (C4) content measured by 13C-NMR analysis (as described in the experimental part) in the range of 6.0 to 10.0 wt.-% with respect to the total weight of the first polymer component (TERPO-2) and
• (iii) optionally one or more additives, selected from the group consisting of slip agents, anti-block agents, UV stabilizers, antistatic agents, alpha-nucleating agents, antioxidants and mixtures thereof;
• wherein the core layer (CL) is a polypropylene-based layer and
• wherein the biaxially oriented polypropylene-based multilayer film has
• a sealing initiation temperature measured on a 25 μm biaxially oriented test cast film as described in the experimental part in the range of 80 to 105° C.