Configuration of multiple thermoformable film layers for rigid packaging requiring moisture and oxygen protection

Abstract

A four-layer film for packaging, including blister packaging, is described. Layer 1 may be a rigid film, such as a polyvinyl chloride (PVC) or polyester. Layer 2 may be a moisture barrier, such as polychlorotrifluoroethylene (PCTFE). Layer 3 may be an oxygen barrier, such as a co-extruded film having a polyethylene (PE) layer, an EVOH layer, and a second PE layer. Layer 4 may be a relatively thin layer of a rigid film, such as a PVC or polyester. In this arrangement, Layer 2 may protect the contents of the package from external or atmospheric moisture. Layer 2 may also protect Layer 3 from atmospheric moisture, thereby helping to preserve the effectiveness of Layer 3 as an oxygen barrier.

What is claimed is: 
     
         1 . A film comprising:
 a first layer that forms a base layer for the film and that is exposable directly to an ambient atmosphere;   a second layer that comprises a moisture barrier;   a third layer that comprises an oxygen barrier; and   a fourth layer that comprises a thin layer of a rigid film.   
     
     
         2 . The film of  claim 1 , wherein the first layer is attached to the second layer via lamination. 
     
     
         3 . The film of  claim 1 , wherein the fourth layer comprises a first gloss on a first side of the layer and a second gloss on a second side of the layer, wherein the first gloss has a greater gloss level than the second gloss. 
     
     
         4 . The film of  claim 3 , wherein the third layer is laminated to the first side of the fourth layer. 
     
     
         5 . An oxygen and moisture protected blister package, comprising:
 a multi-layer film forming a cavity in the blister package, the multi-layer film comprising:   a first layer forming a base layer of the multi-layer film and comprising at least one of polyvinyl chloride and polyester;   a second layer forming a moisture barrier layer and comprising ethylene vinyl alcohol copolymer;   a third layer forming an oxygen barrier layer; and   a fourth layer comprising a higher gloss side and a lower gloss side.