Peelable package

Abstract

A peelable package comprise a first sealant layer comprising low density polyethylene and a first contaminant and a second sealant layer comprising polyethylene polymer, such as high density polyethylene, low density polyethylene, ethylene alpha-olefin copolymer or blends of such, and a second contaminant. The first contaminant and the second contaminant are selected from the group consisting propylene/ethylene copolymer with ethylene content from about 0.1 mol % to about 5 mol %, polypropylene homopolymer, butene/ethylene copolymer and polybutene homopolymer. The first contaminant of the first sealant layer may be the same as or different than the second contaminant of the second sealant layer. Also described are various embodiments of the first sealant layer, the second sealant layer and the peelable seal that is formed between the first sealant layer and the second sealant layer.

What is claimed is as follows: 
     
         1 . A package comprising
 a first sealant layer comprising low density polyethylene in an amount from about 70% to about 95% by weight of the first sealant layer and a first contaminant in an amount from about 5% to about 30% by weight of the first sealant layer, wherein the first contaminant comprises propylene/ethylene copolymer with ethylene content from about 0.1 mol % to about 5 mol %, polypropylene homopolymer, butene/ethylene copolymer or polybutene homopolymer; and   a second sealant layer comprising polyethylene polymer in an amount from about 70% to about 90% by weight of the second sealant layer, wherein the polyethylene polymer comprises high density polyethylene, low density polyethylene, ethylene alpha-olefin copolymer or blends of such, and a second contaminant in an amount from about 10% to about 30% by weight of the second sealant layer, wherein the second contaminant comprises propylene/ethylene copolymer with ethylene content from about 0.1 mol % to about 5 mol %, polypropylene homopolymer, butene/ethylene copolymer or polybutene homopolymer.   
     
     
         2 . The package of  claim 1  further comprising a first film and a second film, wherein the first film comprises the first sealant layer and the second film comprises the second sealant layer. 
     
     
         3 . The package of  claim 2  wherein the first film is a sheet thermoformed into a cup and the second film is a film that is slit or die cut into a lidding film. 
     
     
         4 . The package of  claim 1  wherein the first sealant layer and the second sealant layer are adapted to be sealed together to form a peelable seal having a burst strength greater than about 7.4 psi in accordance with ASTM F2054 and having an initial opening force of less than about 2,500 g/inch in accordance with ASTM F88 or with ASTM F88 as modified for a 45-degree tray peel test. 
     
     
         5 . The package of  claim 4  wherein the peelable seal is a contour seal. 
     
     
         6 . The package of  claim 4  wherein the burst strength is between about 10 psi and 50 psi and the initial opening force is between about 0 g/inch and 2,000 g/inch. 
     
     
         7 . The package of  claim 4  wherein the first sealant layer and the second sealant layer are adapted to be sealed together (1) at a sealing temperature from about 210° C. to about 225° C. and a sealing pressure of from about 43 psi to about 87 psi or (2) at a sealing temperature from about 120° C. to about 130° C. and a sealing pressure about 50 psi or (3) at a sealing temperature from about 220° C. to about 230° C. and a sealing pressure from about 20 psi to about 25 psi. 
     
     
         8 . The package of  claim 1  wherein the first contaminant is in an amount from about 10% to about 25% by weight of the first sealant layer. 
     
     
         9 . The package of  claim 1  wherein the second contaminant is in an amount from about 15% to about 25% by weight of the second sealant layer. 
     
     
         10 . The package of  claim 1  wherein the low density polyethylene of the first sealant layer has a melt index from about 0.6 g/10 min to about 20 g/10 min (at 190° C./2.16 kg). 
     
     
         11 . The package of  claim 1  wherein the first sealant layer has a thickness from about 1 mil to about 5 mil. 
     
     
         12 . The package of  claim 1  wherein the polyethylene polymer of the second sealant layer comprises high density polyethylene. 
     
     
         13 . The package of  claim 1  wherein the polyethylene polymer of the second sealant layer comprises a blend of a first high density polyethylene and a second high density polyethylene. 
     
     
         14 . The package of  claim 1  wherein the polyethylene polymer of the second sealant layer comprises a blend of high density polyethylene and low density polyethylene. 
     
     
         15 . The package of  claim 1  wherein the polyethylene polymer of the second sealant layer comprises low density polyethylene. 
     
     
         16 . The package of  claim 1  wherein the polyethylene polymer of the second sealant layer comprises a blend of low density polyethylene and ethylene alpha-olefin copolymer. 
     
     
         17 . The package of  claim 1  wherein the package is an aseptic package. 
     
     
         18 . An aseptic package comprising
 a first film comprising a first sealant layer comprising low density polyethylene in an amount from about 75% to about 90% by weight of the first sealant layer and a random butene-1/ethylene copolymer in an amount from about 10% to about 25% by weight of the first sealant layer; and   a second film comprising a second sealant layer comprising a first high density polyethylene in an amount from about 50% to about 65% by weight of the second sealant layer, a second high density polyethylene in an amount from about 15% to about 25% by weight of the second sealant layer and a polybutene homopolymer in an amount of from about 15% to about 25% by weight of the second sealant layer.   
     
     
         19 . The package of  claim 18  wherein the first film is a sheet thermoformed into a cup and the second film is a film that is slit or die cut into a lidding film. 
     
     
         20 . The package of  claim 18  wherein the first sealant layer and the second sealant layer are adapted to be sealed together to form a peelable seal having a burst strength between about 10 psi and 50 psi in accordance with ASTM F2054 and an initial opening force between about 0 g/inch and 2,000 g/inch in accordance with ASTM F88 or with ASTM F88 as modified for a 45-degree tray peel test. 
     
     
         21 . The package of  claim 20  wherein the peelable seal is a contour seal. 
     
     
         22 . The package of  claim 20  wherein the first sealant layer and the second sealant layer are adapted to be sealed together (1) at a sealing temperature from about 210° C. to about 225° C. and a sealing pressure of from about 43 psi to about 87 psi or (2) at a sealing temperature from about 120° C. to about 130° C. and a sealing pressure about 50 psi or (3) at a sealing temperature from about 220° C. to about 230° C. and a sealing pressure from about 20 psi to about 25 psi. 
     
     
         23 . The package of  claim 18  wherein the low density polyethylene of the first sealant layer has a melt index from about 0.6 g/10 min to about 20 g/10 min (at 190° C./2.16 kg). 
     
     
         24 . The package of  claim 18  wherein the first sealant layer has a thickness from about 1 mil to about 5 mil.