FIELD OF THE INVENTION

The present invention concerns polyethylene composition comprising a linear low-density copolymer of ethylene (LLDPE) having relatively high MIF/MIE values, i.e. of 20 or more, and a low density polyethylene (LDPE) having relatively high molecular weights.

The films obtainable from the said composition possess an excellent balance of mechanical properties and good optical properties.

BACKGROUND OF THE INVENTION

Achieving an optimal balance of mechanical properties in LLDPE films, in particular of impact resistance (Dart Drop) and tear resistance, is a very challenging goal.

The problem is well illustrated in the examples WO2012/109246, where the highest Dart Drop values are obtained in correspondence with relatively low tear resistance (Elmendorf) values, and vice versa.

It has now been found that such problem can be solved by the compositions of the present invention, which are able to provide films with high Dart Drop and Elmendorf values in combination. Moreover the Elmendorf values in the machine direction (MD) and in the transversal direction (TD) are very close each other, consequently avoiding the occurrence of a preferred tear direction.

SUMMARY OF THE INVENTION

Thus the present invention provides a polyethylene composition comprising (all percentages being by weight):A) from 90 to 99.7%, preferably from 90 to 99%, in particular from 92 to 99%, of a LLDPE having a density from 0.91 to 0.94 g/cm3, preferably from 0.91 to 0.93 g/cm3, determined according to ISO 1183 at 23° C., and a ratio MIF/MIE equal to or higher than 20, where MIF is the melt flow index at 190° C. with a load of 21.60 kg, and MIE is the melt flow index at 190° C. with a load of 2.16 kg, both determined according to ISO 1133;B) from 0.3 to 10%, preferably from 1 to 10%, in particular from 1 to 8%, of a LDPE having MIE from 0.1 to 0.6 g/10 min., preferably from 0.1 to 0.4 g/10 min.

