Blown grade showing superior stiffness, transparency and processing behaviour

摘要

Extrusion blown film comprising a polypropylene composition, said polypropylene composition comprises a random propylene copolymer, a high melt strength polypropylene, and optionally a clarifier, wherein • the random propylene copolymer comprises units derived from propylene and at least another C2 to C20 α-olefin. • the high melt strength polypropylene has a branching index g′ of less than 1.0. • the clarifier comprises at least one α-nucleating agent, and wherein further • the branching index g′ of the random propylene copolymer is higher than the branching index g′ of the high melt strength polypropylene, • the extrusion melt blown film and/or the polypropylene composition, (i) fulfill(s) the equation (I) Tm−Tc≦30 wherein Tm is the melting temperature [° C.] making up more than 50% of the total melting enthalpy Hm of the extrusion melt blown film or of the polypropylene composition measured by DSC according to ISO 11357-3; Tc is the crystallization temperature [° C.] of the extrusion melt blown film or of the polypropylene composition measured by DSC according to ISO 11357-3; and/or (ii) has (have) a melt flow rate MFR2 (230° C.) measured according to ISO 1133 of 1.0 to 5.5 g/10 min.

主权项

1. Extrusion blown film comprising a polypropylene composition, said polypropylene composition comprising a random propylene copolymer (R-PP), a high melt strength polypropylene (HMS-PP), and optionally a clarifier (C), wherein
(a) the random propylene copolymer (R-PP) comprises units derived from propylene and at least another C2 to C20 α-olefin, (b) the high melt strength polypropylene (HMS-PP) has a branching index g′ of less than 1.0, (c) the clarifier (C) comprises at least one α-nucleating agent (N), and wherein the polypropylene composition comprises 70.0 to 95.0 wt.-% of the random propylene copolymer (R-PP), 5.0 to 20.0 wt.-% of the high melt strength polypropylene (HMS-PP), and 0.01 to 5.0 wt.-% of the clarifier (C), based on the total polypropylene composition; and, wherein further (i) the branching index g′ of the random propylene copolymer (R-PP) is higher than the branching index g′ of the high melt strength polypropylene (HMS-PP), (ii) the extrusion blown film
(α) fulfills the equation (I)
Tm−Tc≦30  (I)whereinTm is the melting temperature [° C.] making up more than 50% of the total melting enthalpy Hm of the extrusion blown film measured by DSC according to ISO 11357-3;Tc is the crystallization temperature [° C.] of the extrusion blown film measured by DSC according to ISO 11357-3;and(β) has a melt flow rate MFR2 (230° C.) measured according to ISO 1133 of 1.0 to 5.5 g/10 min.