Multilayer heat sealant structures, packages and methods of making the same

Abstract

The embodiments of the present invention relate to multilayer thermoplastic structures having improved sealability and tearability. More specifically, the present invention relates to a multilayer heat sealant structure having at least three layers that may be coextrusion coated or otherwise laminated to a substrate, such as metallized polymeric material, foil, or other substrates.

1 . A multilayer structure comprising: 
 a coextruded multilayer heat sealant structure comprising a first layer comprising a thermoplastic polymeric material, a second layer comprising low density polyethylene disposed adjacent to and coextruded with the first layer, and a third layer comprising a single site catalyzed polyethylene for use as a heat sealant layer wherein the third layer is disposed adjacent to the second layer and further wherein the third layer is coextruded with the first and second layers.    
     
     
         2 . The multilayer structure of  claim 1  wherein the coextruded multilayer heat sealant structure is laminated to a substrate.  
     
     
         3 . The multilayer structure of  claim 2  wherein the substrate comprises a metallized layer wherein the first layer of the coextruded multilayer heat sealant structure is laminated to the metallized layer.  
     
     
         4 . The multilayer structure of  claim 1  wherein the first layer of said coextruded multilayer heat sealant structure comprises ethylene acrylic acid copolymer.  
     
     
         5 . The multilayer structure of  claim 1  wherein the second layer comprises a blend of low density polyethylene and high density polyethylene.  
     
     
         6 . The multilayer structure of  claim 1  wherein the third layer comprises metallocene-based single site catalyzed polyethylene.  
     
     
         7 . The multilayer structure of  claim 1  wherein the third layer comprises a blend of the single site catalyzed polyethylene and low density polyethylene.  
     
     
         8 . The multilayer structure of  claim 2  wherein the coextruded multilayer heat sealant structure is coextrusion coated to the second structure.  
     
     
         9 . The multilayer structure of  claim 1  wherein the heat sealant structure is made by blown coextrusion.  
     
     
         10 . The multilayer structure of  claim 1  wherein the single site catalyzed polyethylene has a density of about 0.912 g/cc and a melt index of about 12 g/10 min at 190° C.  
     
     
         11 . The multilayer structure of  claim 1  wherein the single site catalyzed polyethylene has a density of about 0.910 g/cc and a melt index of about 15 g/10 min. at 190° C.  
     
     
         12 . A package for a product comprising: 
 a first multilayer structure comprising a coextruded multilayer heat sealant structure comprising a first layer comprising a thermoplastic polymeric material, a second layer comprising low density polyethylene disposed adjacent to and coextruded with the first layer, and a third layer comprising a single site catalyzed polyethylene for use as a heat sealant layer wherein said third layer is disposed adjacent to the second layer and further wherein the third layer is coextruded with the first and second layers; and    a second multilayer structure heat sealed to the first multilayer structure to form the package with a space therein for the product.    
     
     
         13 . The package of  claim 12  wherein the coextruded multilayer heat sealant structure is laminated to a substrate.  
     
     
         14 . The package of  claim 13  wherein the substrate comprises a metallized layer wherein the first layer is laminated to the metallized layer.  
     
     
         15 . The package of  claim 12  wherein the first layer of the coextruded multilayer heat sealant structure comprises ethylene acrylic acid copolymer.  
     
     
         16 . The package of  claim 12  wherein the second layer comprises a blend of low density polyethylene and high density polyethylene.  
     
     
         17 . The package of  claim 12  wherein the third layer comprises metallocene-based single site catalyzed polyethylene.  
     
     
         18 . The package of  claim 12  wherein the third layer comprises a blend of the single site catalyzed polyethylene and low density polyethylene.  
     
     
         19 . The package of  claim 13  wherein the coextruded multilayer heat sealant structure is coextrusion coated to the substrate.  
     
     
         20 . The package of  claim 12  wherein the coextruded multilayer heat sealant structure is made by blown coextrusion.  
     
     
         21 . The package of  claim 12  wherein the second multilayer structure is identical to the first multilayer structure.  
     
     
         22 . The package of  claim 12  wherein the single site catalyzed polyethylene has a density of about 0.912 g/cc and a melt index of about 12 g/10 min. at 190° C.  
     
     
         23 . The package of  claim 12  wherein the single site catalyzed polyethylene has a density of 0.910 g/cc and a melt index of about 15 g/10 min. at 190° C.  
     
     
         24 . A method of making a multilayer structure comprising the steps of: 
 coextruding a multilayer heat sealant structure comprising a first layer comprising a thermoplastic polymeric material, a second layer comprising low density polyethylene wherein said second layer is disposed adjacent to the first layer, and a third layer comprising a single site catalyzed polyethylene wherein the third layer is disposed adjacent to the second layer; and    laminating said first layer of said multilayer sealant structure to a substrate.    
     
     
         25 . The method of  claim 24  wherein the substrate comprises a metallized layer.  
     
     
         26 . The method of  claim 24  wherein the first layer comprises ethylene acrylic acid copolymer.  
     
     
         27 . The method of  claim 24  wherein the second layer comprises a blend of the low density polyethylene and a high density polyethylene.  
     
     
         28 . The method of  claim 24  wherein the third layer comprises a blend of the single site catalyzed polyethylene and low density polyethylene.  
     
     
         29 . The method of  claim 24  wherein the multilayer heat sealant layer is made via blown coextrusion.  
     
     
         30 . The method of  claim 24  further comprising coextrusion coating the multilayer heat sealant structure to the substrate.  
     
     
         31 . The method of  claim 24  wherein the single site catalyzed polyethylene has a density of about 0.912 g/cc and a melt index of about 12 g/10 min. at 190° C.  
     
     
         32 . The method of  claim 24  wherein the single site catalyzed polyethylene has a density of about 0.910 g/cc and a melt index of about 15 g/10 min. at 190° C.  
     
     
         33 . The method of  claim 24  wherein said multilayer heat sealant structure comprises a first coextruded substructure comprising the first layer and a first part of the second layer laminated to a second coextruded substructure comprising a second part of the second layer and the third layer, wherein the first and second parts of the second layer are laminated together to form a single layer.