Rigid Packages Having Peelable Hermetic Seals

Abstract

The disclosed principles provide for a welding technique welding the flanges of a rigid lid sealed onto a rigid tray, such that the two may be easily separated but still repeatedly reclosable such that the rigid package may be reused. For this unique and advantageous ultrasonic welding technique, the disclosed principles provide for the inclusion of a unique delamination layer between the similar rigid materials used for forming the flanges of both the lid and the tray. The disclosed principles provide for the delamination layer to be provide on one or both of the two rigid materials, but behind the seal interphase area so that the hermitic seal may still be created. This delamination layer operates such that it peels apart (i.e., delaminates) as the ultrasonically sealed rigid material of the lid flange and rigid material of the tray flange are pulled apart while opening the package initially.

What is claimed is: 
     
         1 . A hermetically sealed package, comprising:
 a first flange comprised of a rigid plastic and having a first mating surface;   a first laminated layer disposed on the first mating surface of the first flange, wherein the first laminated layer comprises a delamination layer and a sealant layer positioned as the outermost layer of the first laminated layer;   a second flange comprised of a rigid plastic and having a second mating surface configured to be ultrasonically welded to the first mating surface;   a second laminated layer disposed on the second mating surface of the second flange, wherein the second laminated layer comprises a sealant layer positioned as the outermost layer of the second laminated layer; and   wherein the first and second mating surfaces with the first and second laminated stacks interposed are ultrasonically welded to one another such that the first and second sealant layers are hermetically sealed.   
     
     
         2 . A package according to  claim 1 , wherein the delamination layer comprises ethylene propylene polymer (EP). 
     
     
         3 . A package according to  claim 1 , further comprising a barrier layer disposed between the delamination layer and the sealant layer. 
     
     
         4 . A package according to  claim 3 , wherein the barrier layer comprises ethylene-vinyl alcohol copolymer (EVOH). 
     
     
         5 . A package according to  claim 1 , further comprising an adhesive layer disposed between the delamination layer and the rigid plastic of the first flange. 
     
     
         6 . A package according to  claim 5 , wherein the adhesive layer comprises polyethylene (PE). 
     
     
         7 . A package according to  claim 1 , wherein one or both of the first and second sealant layers is comprised of ethylene vinyl acetate (EVA). 
     
     
         8 . A package according to  claim 1 , wherein the sealant layer of the first laminated layer and the sealant layer of the second laminated layer are comprised of the same material. 
     
     
         9 . A package according to  claim 1 , wherein one or both of the rigid plastic comprising the first and second flanges comprises amorphous polyethylene terephthalate (APET), crystalline polyethylene terephthalate (CPET), polyethylene terephthalate glycol (PETG), polypropylene (PP), and polystyrene (PS), or a combination of one or more of these materials. 
     
     
         10 . A package according to  claim 1 , wherein the first and second flanges comprise APET;
 wherein the first laminated layer comprises:
 a delamination layer comprising EP, 
 an adhesive layer comprising PE between the first mating surface and the delamination layer, 
 a barrier layer comprising EVOH on the delamination layer, 
 a sealant layer comprising EVA disposed on the barrier layer; and 
   wherein the second laminated layer comprises:
 a barrier layer comprising EVOH, 
 an adhesive layer comprising PE between the second mating surface and the barrier layer, 
 a sealant layer comprising EVA disposed on the barrier layer. 
   
     
     
         11 . A package according to  claim 10 , wherein the first flange is formed to a thickness of 18-28 mils and the first laminated layer is formed to a thickness of 1.5-2.5 mils, and wherein the second flange is formed to a thickness of 18-28 mils and the second laminated later is formed to a thickness of 1.5-2.5 mils. 
     
     
         12 . A package according to  claim 1 , wherein the delamination layer is configured to be peeled apart with a force in the range of 1.5 lbf to 4.0 lbf. 
     
     
         13 . A package according to  claim 1 , wherein the second laminated layer comprises a delamination layer disposed between the sealant layer and the second mating surface. 
     
     
         14 . A package according to  claim 1 , wherein the first laminated layer on the first mating surface is coextruding with the first flange. 
     
     
         15 . A method for providing a peelable hermetic seal on a rigid package, the method comprising:
 providing a first flange comprised of a rigid plastic and having a first mating surface;   forming a first laminated layer on the first mating surface of the first flange, wherein the first laminated layer comprises a delamination layer and a sealant layer positioned as the outermost layer of the first laminated layer;   providing a second flange comprised of a rigid plastic and having a second mating surface configured to be ultrasonically welded to the first mating surface;   forming a second laminated layer on the second mating surface of the second flange, wherein the second laminated layer comprises a sealant layer positioned as the outermost layer of the second laminated layer; and   ultrasonically welding the first and second mating surfaces with the first and second laminated stacks interposed therebetween such that the first and second sealant layers are hermetically sealed to one another.   
     
     
         16 . A method according to  claim 15 , wherein the delamination layer comprises ethylene propylene polymer (EP). 
     
     
         17 . A method according to  claim 15 , further comprising disposing a barrier layer between the delamination layer and the sealant layer. 
     
     
         18 . A method according to  claim 17 , wherein the barrier layer comprises ethylene-vinyl alcohol copolymer (EVOH). 
     
     
         19 . A method according to  claim 15 , further comprising disposing an adhesive layer between the delamination layer and the rigid plastic of the first flange. 
     
     
         20 . A method according to  claim 19 , wherein the adhesive layer comprises polyethylene (PE). 
     
     
         21 . A method according to  claim 15 , wherein one or both of the first and second sealant layers is comprised of ethylene vinyl acetate (EVA). 
     
     
         22 . A method according to  claim 15 , wherein the sealant layer of the first laminated layer and the sealant layer of the second laminated layer are comprised of the same material. 
     
     
         23 . A method according to  claim 15 , wherein one or both of the rigid plastic comprising the first and second flanges comprises amorphous polyethylene terephthalate (APET), crystalline polyethylene terephthalate (CPET), polyethylene terephthalate glycol (PETG), polypropylene (PP), and polystyrene (PS), or a combination of one or more of these materials. 
     
     
         24 . A method according to  claim 15 , wherein the first and second flanges comprise APET;
 wherein the first laminated layer comprises:
 a delamination layer comprising EP, 
 an adhesive layer comprising PE between the first mating surface and the delamination layer, 
 a barrier layer comprising EVOH on the delamination layer, 
 a sealant layer comprising EVA disposed on the barrier layer; and 
   wherein the second laminated layer comprises:
 a barrier layer comprising EVOH, 
 an adhesive layer comprising PE between the second mating surface and the barrier layer, 
 a sealant layer comprising EVA disposed on the barrier layer. 
   
     
     
         25 . A method according to  claim 24 , wherein the first flange is formed to a thickness of 18-28 mils and the first laminated layer is formed to a thickness of 1.5-2.5 mils, and wherein the second flange is formed to a thickness of 18-28 mils and the second laminated later is formed to a thickness of 1.5-2.5 mils. 
     
     
         26 . A method according to  claim 25 , wherein ultrasonically welding the first and second mating surfaces with the first and second laminated stacks interposed therebetween further comprising employing welding parameters of:
 350 ms-450 ms weld time;   260 J-450 J weld energy;   ˜1500 Watts weld power;   ˜210-250 lbs weld force;   ˜250 lbs trigger force; and   ˜35 um amplitude.   
     
     
         27 . A method according to  claim 25 , wherein ultrasonically welding the first and second mating surfaces with the first and second laminated stacks interposed therebetween further comprising employing welding parameters of:
 900 ms-1100 ms weld time;   305 J weld energy;   ˜1500 Watts weld power;   ˜135 lbs weld force;   ˜250 lbs trigger force; and   ˜10 um amplitude.   
     
     
         28 . A method according to  claim 15 , wherein the delamination layer is configured to be peeled apart with a force in the range of 1.5 lbf to 4.0 lbf. 
     
     
         29 . A method according to  claim 15 , wherein the second laminated layer comprises a delamination layer disposed between the sealant layer and the second mating surface. 
     
     
         30 . A method according to  claim 29 , wherein forming a first laminated layer on the first mating surface of the first flange further comprises coextruding the first laminated layer with the first flange.