Package making – Methods – Conforming by stretching or shrinking of cover over contents
Patent
1997-06-11
1999-06-01
Johnson, Linda
Package making
Methods
Conforming by stretching or shrinking of cover over contents
B65B 5300
Patent
active
059079436
ABSTRACT:
A method for wrapping a multilayer, thermoplastic stretch wrap film containing at least three polymeric film layers and comprised of an inner polymeric layer. The inner polymeric layer comprises a blend of a low polydispersity polymer and either a high pressure low density polyethylene resin, a very low density polyethylene resin or a combination thereof. The low polydispersity polymer has a polydispersity of from about 1 to about 4, a melt index (I.sub.2) of from about 0.5 to about 10 g/10 min., and a melt flow ratio (I.sub.20 /I.sub.2) of from about 12 to about 22. The high pressure low density polyethylene resin has a melt index of from about 1 to about 10 g/10 min., and a density of from about 0.9 to about 0.935 g/cm.sup.3. The very low density polyethylene resin has a melt index of from about 0.5 to about 5 g/10 min., and a density of from about 0.880 to about 0.912 g/cm.sup.3. The stretch wrap film may include a first layer and a second layer. The first and second layers may comprise a polymer of two or more monomers, wherein a first monomer is ethylene, in a major amount by weight, and a second monomer is an alpha olefin of from about 3 to about 12 carbon atoms, in a minor amount by weight. If the first and second layers are outer layers, they have a cling force to each other of at least about 140 grams/inch. The stretch wrap film has a maximum stretch of at least 340% and a F-50 dart drop value of at least about 150 g/mil. It is contemplated that additional outer layers may be added such an outer high cling layer or an outer slip layer, as well as additional inner layers.
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Johnson Linda
Tenneco Packaging Inc.
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