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Abstract

Heat-shrinkable coextrudate thermoplastic film packaging materials, well suited for the packaging of any one or more of a wide variety of articles, e.g., canned goods, and readily torn in a transverse direction substantially perpendicular to the machine direction thereof, include (a) at least one layer of a polyolefin; and (b) at least one layer of an ionic copolymer which comprises the copolymerizate of (1) an .alpha.-olefin of formula R--CH.dbd.CH.sub.2 wherein R is hydrogen or an alkyl radical having from 1 to 8 carbon atoms, with (2) an .alpha.,.beta.-ethylenically unsaturated carboxylic acid having from 3 to 8 carbon atoms, and, optionally, (3) at least one other monoethylenically unsaturated comonomer, with the proviso that from 10% to 90% of the carboxylic acid functional groups of said copolymer are ionized by means of metallic ions distributed over the copolymer, and such films are shaped by coextrusion of (a) the polyolefin layer and (b) the ionic copolymer layer under the following operations conditions: (i) a lengthwise stretch ratio of 2 to 25; and (ii) a frost line height of less than 160 cm; the ratio ##EQU1## being such as to provide a ratio of: ##EQU2## greater than or equal to 2.

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First Claim