LINEAR POLYETHYLENE WITH HIGH MELT YIELD-TO-FILM YIELD RATIO AND FILMS MADE THEREOF BY COEXTRUSION Russian patent published in 2013 - IPC B32B27/32 C08J5/18 B29C49/04 

FIELD: process engineering.

SUBSTANCE: invention relates to packing films and method of their production by blow extrusion. Said film comprises, at least two outer layers and at least one inner layer arranged there between. Outer layers comprises at least one linear ethylene copolymer and alpha-olefin with melt yield ratio (I₂₁/I₂) over 20, density varying from 0.910 to 0.945 g/cm³, distribution of molecular weights (Mw/Mn) from 2.0 to 5.0 and composition distribution factor under 40%. Note here that linear copolymer of ethylene and alpha-olefin incorporate component soluble in xylene at 60°C or lower in amount of at least 5 wt %. Film inner layer comprises at least one polyethylene with common density of at least 0.910 g/cm³.

EFFECT: better optical and mechanical properties and manufacturability.

15 cl, 7 tbl, 2 ex