Gas barrier coating having improved bond strength

Abstract

In order to maintain adequate bond strength of a composite in which a gas barrier coating comprising a clay dispersion and a polymer solution or dispersion of a PVA and/or EVA is positioned between two flexible plastics films using an adhesive, it is necessary that the clay dispersion and the polymer solution or dispersion should be kept separate until shortly before they are to be applied.

1 - 11 . (canceled) 
     
     
         12 . A two pack composition, one pack comprising a solution or dispersion of a PVA and/or EVOH, and the other comprising an aqueous dispersion of a clay. 
     
     
         13 . A composition according to  claim 12 , in which some or all of the clay has been intercalated or exfoliated during dispersion. 
     
     
         14 . A composition according to  claim 12 , in which the clay has an aspect ratio from 20 to 10,000. 
     
     
         15 . A composition according to  claim 12 , in which the amount of polymer is from 40 to 95% of the total solids comprising polymer and clay. 
     
     
         16 . A composition according to  claim 12 , in which the amount of polymer is from 50 to 90% of the total solids comprising polymer and clay. 
     
     
         17 . A gas barrier material comprising at least two flexible polymer films having therebetween: an adhesive layer; and a gas barrier layer comprising a clay and PVA and/or EVOH, the bond strength between said two films being at least 1.0N/15 mm, and more preferably greater than 1.5N/15 mm. 
     
     
         18 . A material according to  claim 17 , in which the clay has been intercalated or exfoliated during dispersion. 
     
     
         19 . A material according to  claim 17 , in which the clay has an aspect ratio from 20 to 10,000. 
     
     
         20 . A material according to  claim 17 , in which the amount of polymer is from 40 to 95% of the total solids comprising polymer and clay. 
     
     
         21 . A material according to  claim 17 , in which the amount of polymer is from 50 to 90% of the total solids comprising polymer and clay. 
     
     
         22 . A material according to  claim 17 , in which the thickness of the coating is from 50 nm to 3000 nm. 
     
     
         23 . A material according to  claim 22 , in which the thickness of the coating is from 200 to 2000 nm. 
     
     
         24 . A kit for preparing a gas barrier material for use with a flexible polymer and an adhesive, comprising:
 a solution dispersion of a PVA and/or EVOH; and   an aqueous dispersion of a clay adapted to be mixed with the PVA and/or EVOH,   wherein the PVA and/or EVOH and the aqueous dispersion of the clay are further adapted to coat the flexible polymer film within  24  hours of completing the mixing, and adapted to receive an adherence with a bond strength at least 1.0 N/15 mm after the adhesive has fully cured.   
     
     
         25 . A package for foodstuff, pharmaceutical or other material sensitive to oxygen, the package comprising a gas barrier material prepared by the kit of  claim 24 .