Polyethylene and Polypropylene Based Tie Resin for Co-Extrusion

Abstract

A tie resin is provided that is an extrudable blend of anhydride modified polypropylene and anhydride modified polyethylene suitable for use as a tie resin in coextrusions of polypropylene, polyethylene, nylon and EVOH materials.

What is claimed: 
     
         1 . A tie resin comprising a blend of at least one polyethylene based tie resin and at least one polypropylene based tie resin. 
     
     
         2 . The tie resin according to  claim 1 , wherein the polyethylene based tie resin comprises at least a polyethylene modified by grafting with ethylenically unsaturated carboxylic anhydrides. 
     
     
         3 . The tie resin according to  claim 2 , wherein the ethylenically unsaturated carboxylic anhydrides are selected from the group consisting of maleic anhydride, Nadic anhydride, Himic anhydride, tetrahydrophthalic anhydride, methyl nadic anhydride, methyl Himid anhydride, and combinations thereof. 
     
     
         4 . The tie resin according to  claim 1 , wherein the polypropylene based tie resin comprises at least a polypropylene modified by grafting with ethylenically unsaturated carboxylic anhydrides. 
     
     
         5 . The tie resin according to  claim 4 , wherein said ethylenically unsaturated carboxylic anhydrides are selected from the group consisting of maleic anhydride, Nadic anhydride, Himic anhydride, tetrahydrophthalic anhydride, methyl nadic anhydride, methyl Himid anhydride, and combinations thereof. 
     
     
         6 . The tie resin according to  claim 1 , wherein the concentration of polyethylene based tie resin is between 10 to 90%. 
     
     
         7 . The tie resin according to  claim 1 , wherein the concentration of polypropylene based tie resin is between 10 to 90%. 
     
     
         8 . The tie resin according to  claim 2 , wherein the polyethylene based tie resin's anhydride concentration is between 0 to 2% by weight and more preferable between 0.3 to 1.5% by weight. 
     
     
         9 . The tie resin according to  claim 4 , wherein the polypropylene based tie resin's anhydride concentration is within 0 to 2% by weight and more preferably between 0.3 to 1.5% by weight. 
     
     
         10 . The tie resin according to  claim 2 , wherein the polyethylene compound of the tie resin has a melt flow index of between 0.4 to 10 g/10 min and preferably between 2.0 and 6.0 g/10 min. 
     
     
         11 . The tie resin according to  claim 4 , wherein the polypropylene compound of the tie resin has a melt flow rate of between 2 to 470 g/10 min, and preferably is between 2.0 to 32 g/10 min. 
     
     
         12 . The tie resin according to  claim 2 , wherein a density of the polyethylene compound is between 0.90 to 0.96 g/cm 3 , and preferably is between 0.91 to 0.93 g/cm 3 . 
     
     
         13 . The tie resin as defined in  claim 4 , wherein the polypropylene compound has a density of between 0.88 and 0.90 g/cm 3 .