Stretch packaging method employing multi-layer film
AssigneeMitsui Petrochemical Industries, Ltd.
InventorsTakashi Matsunaga, Keiichi Miura
Life of this patent
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Abstract
A film for stretch packaging comprising as a substrate a film of a linear low density polyethylene having a melt flow rate (190.degree. C.), as measured by an ASTM-D-1238E method, of 0.3 to 8 g/10 min., a density, as measured by an ASTM-D-1505 method, of 0.900 to 0.918 g/cm.sup.3, a molecular weight distribution (Mw/Mn) of 2 to 6, two or more melting points existing as measured by a differential scanning calorimeter, a maximum melting point Tm.sub.1 of 118.degree. to 125.degree. C. and a ratio of the height Tm.sub.1 H of the peak of the highest melting point Tm.sub.1 to the height Tm.sub.1 H of the melting point Tm.sub.2 adjacent thereto (i.e., Tm.sub.1 H/Tm.sub.2 H), of 1.3 or less.
Claims7
In a method for stretch packaging a plurality of articles by wrapping the articles in a stretchable film while stretching said stretchable film about said articles, the improvement comprising using as said stretchable film a multi-layer film for stretch packaging and having a non-tacky surface and a tacky surface, said multi-layer film comprising an intermediate layer of a linear low density polyethylene having a melt flow rate (190.degree. C.), as measured by an ASTM-D-1238E method, of 0.3 to 8 g/10 min., a density, as measured by an ASTM-D-1505 method, of 0.900 to 0.918 g/cm.sup.3, a molecular weight distribution (Mw/Mn) of 2 to 6, two or more melting points existing as measured by a differential scanning calorimeter, a maximum melting point Tm.sub.1 of 118.degree. to 125.degree. C. and a ratio of the height Tm.sub.1 H of the peak of the highest melting point Tm.sub.1 to the height Tm.sub.2 H of the melting point Tm.sub.2 adjacent thereto (i.e., Tm.sub.1 H/Tm.sub. 2 H), of 1.3 or less, a non-tacky surface layer on one surface of said intermediate layer and comprising a non-tacky linear low density polyethylene having a density greater than 0.918 g/cm.sup.3, and, on the opposite surface of said intermediate layer, a tacky surface layer comprising a mixture of linear low density polyethylene having a melt flow rate (190.degree. C.), as measured by an ASTM-D-1238E method, of 0.3 to 8 g/10 min., a density, as measured by an ASTM-D-1505 method, of 0.900 to 0.918 g/cm.sup.3, a molecular weight distribution (Mw/Mn) of 2 to 6, two or more melting points existing as measured by a differential scanning calorimeter, a maximum melting point Tm.sub.1 of 118.degree. to 125.degree. C. and a ratio of the height Tm.sub.1 H of the peak of the highest melting point Tm.sub.1 to the height Tm.sub.2 H of the melting point Tm.sub.2 adjacent thereto (i.e., Tm.sub.1 H/Tm.sub.2 H), of 1.3 or less and from 2 to 10% by weight of liquid polyisobutylene or liquid polybutadiene, said non-tacky surface layer having a thickness of from about 5 to 30% of the total thickness.
Dependencies are inferred from the claim text.