Blown film coextrusion process comprising: supplying a core layer composition containing at least 90 wt% of an ethylene based polymer or other compatible linear olefin based polymer of which at least 5 wt% is an LDPE with a I 2.16 ldpe-core of 1.5 g/10 min or less and from 0 to 10 wt% of a balance of a heterogeneously branched ethylene based polymer other than LDPE; supplying a pair of core contact layer compositions, each containing at least 90 wt% of ethylene based polymer of which at least 75 wt% is a linear polyethylene with a I 2.16 linear pe-skin of 2.5 g/10 min or less, preferably less than 2, even more preferably 1.8, and an I 21.6 linear pe-skin/ I 2.16 linear pe-skin ratio below 30; wherein the ratio of the zero shear viscosity calculated from determinations of viscosity at different shear rates at 190°C using the Cross model of the individual ethylene based polymers in the core contact layer compositions over that of the core layer composition is less than 0.9 and wherein the core layer has an average density of ethylene based polymers as measured by ASTM D2839/D1505 equal to or higher than that of the core contact layers; and melting and extruding core and core contact adjacent both sides of the core layer through a die exit at a linear speed V o cm/s and cooling, orienting and crystallizing the multilayer film formed at a deformation rate E avg =(Vf-Vo)/ FLH > 0.6 until a frost line is reached at a distance FLH from the die exit by drawing the film at a take up speed V f in cm/s at the frost line, all I 2.16 ldpe values being determined according to ASTM D 1238 procedure A condition 190°C/2.16 kg. supplying a core layer composition containing at least 90 wt% of an ethylene based polymer or other compatible linear olefin based polymer of which at least 5 wt% is an LDPE with a I 2.16 ldpe-core of 1.5 g/10 min or less and from 0 to 10 wt% of a balance of a heterogeneously branched ethylene based polymer other than LDPE; supplying a pair of core contact layer compositions, each containing at least 90 wt% of ethylene based polymer of which at least 75 wt% is a linear polyethylene with a I 2.16 linear pe-skin of 2.5 g/10 min or less, preferably less than 2, even more preferably 1.8, and an I 21.6 linear pe-skin/ I 2.16 linear pe-skin ratio below 30; wherein the ratio of the zero shear viscosity calculated from determinations of viscosity at different shear rates at 190°C using the Cross model of the individual ethylene based polymers in the core contact layer compositions over that of the core layer composition is less than 0.9 and wherein the core layer has an average density of ethylene based polymers as measured by ASTM D2839/D1505 equal to or higher than that of the core contact layers; and melting and extruding core and core contact adjacent both sides of the core layer through a die exit at a linear speed V o cm/s and cooling, orienting and crystallizing the multilayer film formed at a deformation rate E avg =(Vf-Vo)/ FLH > 0.6 until a frost line is reached at a distance FLH from the die exit by drawing the film at a take up speed V f in cm/s at the frost line, all I 2.16 ldpe values being determined according to ASTM D 1238 procedure A condition 190°C/2.16 kg.