Stretch hood films
View Patent ↗A multi-layer film structure is made from a specific polyethylene copolymer comprising the inner layer and is useful as a stretch hood film structure. The polyethylene copolymer can be characterized by a Comonomer Distribution Constant greater than about 45.
1. A multi-layer film having a thickness of at least 3 mils comprising at least one inner layer and two exterior layers, wherein the inner layer comprises at least 50 weight percent polyethylene copolymer having a melt index less than 2 grams/10 minutes, a density less than or equal to 0.910 g/cm 3 , an overall heat of fusion less than 120 Joules/gram and a heat of fusion above 115° C. of less than 5 Joules/gram, and a total heat of fusion of the inner layer less than a heat of fusion of either of the two exterior layers, and wherein the multi-layer film has an elastic recovery of at least 40% when stretched to 100% elongation.
2. The multi-layer film of claim 1 wherein the polyethylene copolymer in the inner layer has a Mw/Mn of at least 2.5.
3. The multi-layer film of claim 1 wherein the polyethylene copolymer of the inner layer is characterized by up to about 3 long chain branches/1000 carbons.
4. The multi-layer film of claim 1 wherein the polyethylene copolymer of the inner layer comprises a single DSC melting peak.
5. The multi-layer film of claim 1 wherein the polyethylene copolymer of the inner layer is characterized by a Comonomer Distribution Constant greater than about 45 and as high as 400, and wherein the polyethylene copolymer has less than 120 total unsaturation unit/1,000,000 C.
6. The multi-layer film of claim 5 wherein the polyethylene copolymer of the inner layer is further characterized as comprising less than 20 vinylidene unsaturation unit/1,000,000 C.
7. The multi-layer film of claim 1 , wherein the exterior layers are less than 50 weight percent of the total film.
8. The multi-layer film of claim 1 wherein the film has 3 layers and is made using a blown film process.
9. A stretch hood film structure formed from a film as in claim 1 , 7 or 8 .