Tenneco Packaging Inc.

Mobil Oil Corporation

George N Eichbauer

David V Dobreski

Edward M Bullard

Richard E Leone

Michael E Leach

W Mark Dutt

Robert J Silver

Beth A LeBlanc

A multilayer, thermoplastic stretch wrap film containing at least three polymeric film layers and comprised of 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 also has at least one inner polymeric layer, located between the first and second layers. The inner polymeric layer comprises a low polydispersity polymer having 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 inner layer(s) comprise(s) from about 5 wt. % to about 40 wt. % of the stretch wrap film so as to produce a film having a maximum stretch of at least 340%, a F-50 dart drop value of at least about 130 g/mil, a machine directional tear resistance of at least about 125 g/mil and a transverse directional tear resistance of at least about 500 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.

Stretch wrap films

A multilayer, thermoplastic roll wrap film containing at least three polymeric film layers and comprised of an outer cling layer, a non-cling outer layer, and at least one inner polymeric layer. The roll wrap film has at least one inner polymeric layer, located between the outer cling layer and then non-cling outer layer. The non-cling outer layer is preferably comprised of a high pressure, low density polyethylene resin having a melt index of from about 0.5 to about 6. The inner polymeric layer comprises a low polydispersity polymer. 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 roll wrap film has a transverse tear resistance of at least 400 grams/mil as measured by ASTM D1922, a machine direction tear resistance as measured by ASTM D1922 of at least 150 grams/mil and a F-50 dart drop of at least 600 grams. It is contemplated that additional layers may be added to the present invention.

Roll wrap film

The present invention provides for improved polyolefin stretch wrap films having superior cling force, load retention, tear resistance and puncture resistance properties and for the methods of using those stretch wrap films. The stretch wrap films generally have a thickness of from about 0.4 to about 3 mils, a cling force onto itself of at least 140 g/inch, an F-50 dart drop strength of at least about 150 g/mil. The stretch wrap films are constructed in a multilayer fashion having at least one outside cling polyethylene copolymer layer containing a polyethylene resin preferably produced through metallocene catalyst technology.

The present invention provides for improved polyolefin cling/slip stretch wrap films having superior load retention, elongation, tear resistance and puncture resistance properties and for the methods of using those stretch wrap films. The stretch wrap films are preferably constructed in a multilayer fashion having an outside cling layer, an outside slip layer, at least one inside puncture resistant layer comprising a metallocene-catalyzed polyethylene resin, and at least one inside transverse direction tear resistant layer.

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.

A method of stretch wrapping an item with a multilayer, thermoplastic stretch wrap film. The stretch wrap film containing at least three polymeric film layers and comprised of 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 also has at least one inner polymeric layer, located between the first and second layers. The inner polymeric layer comprises a low polydispersity polymer having 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 inner layer(s) comprise(s) from about 5 wt. % to about 40 wt. % of the stretch wrap film so as to produce a film having a maximum stretch of at least 340%, a F-50 dart drop value of at least about 130 g/mil, a machine directional tear resistance of at least about 125 g/mil and a transverse directional tear resistance of at least about 500 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.

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.

A multilayer, thermoplastic stretch wrap film containing at least four polymeric film layers and comprised of a first outer cling layer, a second outer cling layer, at least one inner polymeric layer and at least one core layer. The first and second layers have a cling force to s each other of at least about 140 grams/inch. The stretch wrap film has at least one inner polymeric layer, located between the first and second layers. The inner polymeric layer comprises a low polydispersity polymer. 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 core layer, also located between the outer cling layers, comprises either a random copolymer of propylene and ethylene, a heterophasic copolymer of propylene with domains of ethylene interspersed, a polypropylene homopolymer, or blends thereof. The random ethylene-propylene copolymer has a melt flow ratio of from about 2 to about 15 and an ethylene content in the range of from about 2 to about 6 wt. % of the propylene copolymer. The heterophasic copolymer has a melt flow ratio of about 10 to about 18 and an ethylene content in the range of from about 12 to 30 wt. % of the heterophasic propylene. The polypropylene homopolymer has a melt flow ratio of from about 2 to about 15. The multilayer stretch wrap film has a maximum stretch of at least 340% and a machine direction stress force @ 200% elongation of between about 1400 and about 1900 psi. It is contemplated that additional layers may be added to the present invention.

Multilayered Metallocene stretch wrap films

The present invention provides for improved thermoplastic stretch wrap films having superior cling force, load retention, elongation, tear resistance and puncture resistance properties and for the methods of using those stretch wrap films. The stretch wrap films generally have a thickness of from about 0.4 to about 3 mils. The stretch wrap films are preferably constructed in a multilayer fashion having outside cling layers, and at least one inside puncture resistant layer comprising a metallocene-catalyzed polyethylene resin and at least one inside transverse direction tear resistant layer comprising a polyethylene copolymer.

The present invention relates to multilayer coextruded thermoplastic stretch wrap films useful for the packaging or palletizing of goods. More particularly the films of this invention comprise at least three layers having two outer layers and at least one intermediate layer placed between the outer layers. The intermediate layer includes a low melt index linear low density copolymer of ethylene and a minor amount of at least one alpha olefin having from 4 to 10 carbon atoms, the low melt index linear low density copolymer having a melt index of between about 0.5 to about 2.5. At least one of the two outer layers includes a high melt index linear low density copolymer of ethylene and a minor amount of at least one alpha olefin having from 4 to 10 carbon atoms, the high melt index linear low density copolymer having a melt index of greater than about 2.5, the high melt index linear low density copolymer containing from about 3.5 to about 15 weight percent n-hexane extractibles. The n-hexane extractibles are present in an amount sufficient to cause the stretch wrap film to exert a cling force to itself or other surfaces when used in the stretch overwrap packaging of articles.

Multilayer coextruded linear low density polyethylene stretch wrap films

A stretch wrap film having one sided cling comprising a thermoplastic A/B film structure wherein layer A in stretched condition has a comparatively high cling force to layer B and layer B has at least substantially no cling force to a layer of itself.

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Conyers, GA, United States of America

George N Eichbauer