Shrink films of ethylene/α-olefin copolymers

Claim 1

In a process for making a shrink film having high optical clarity, good shrink properties, and good mechanical properties, said film being made by stretching a polymer film at least three times its original linear dimension in at least one direction, the improvement of stretching a film made of the following homogeneous composition: (1) 5-100 weight % of at least one linear copolymer of ethylene with at least one C 8 -C 18 α-olefin, said copolymer having the following characteristics: (a) melt index of 0.1-4.0 g/10 min.; (b) density of 0.900 to 0.940 g/cm 3 ; (c) stress exponent above 1.3; and (d) two distinct crystalline melting regions below 128° C. as determined by differential scanning calorimetry (DSC), the temperature difference between those regions being at least 10° C.; (e) G=[η]/[η] l ν of about 0.85 to 1.00, wherein [η] is the intrinsic viscosity of the copolymer and [η] l ν is the intrinsic viscosity of linear homopolyethylene having the same viscosity-average molecular weight; and (2) 0.95 weight % of at least one polymer selected from the group consisting of α-olefin homopolymers and copolymers with one another or with another ethylenically unsaturated comonomer, said polymer having only one crystalline melting point; with the stretching being carried out without prior crosslinking and at a temperature within the range defined by the two crystallite melting points of the ethylene copolymer with C 8 -C 18 α-olefin of the above paragraph (1) but above any temperature at which tearing may occur.