Multilayer structures of poly(1,3-propylene 2,6-naphthalate and poly ethylene terephthalate)

Abstract

Multilayer shaped articles, including films, preforms and containers, and method for forming the same, having at least one layer of poly(1,3-propylene 2,6-naphthalate) and at least one layer of poly(ethylene terephthalate). Poly(1,3-propylene 2,6-naphthalate) can be co-stretched with poly(ethylene terephthalate) to form oriented multilayer structures which have superior barrier properties. The poly(1,3-propylene 2,6-naphthalate) and poly(ethylene terephthalate) layers have good adhesion and do not require an adhesive tie layer.

What is claimed is:  
     
         1 . A multilayer film or preform comprising at least a first resin layer and a second resin layer wherein the first resin layer comprises poly(1,3-propylene 2,6-naphthalate) and the second resin layer comprises poly(ethylene terephthalate).  
     
     
         2 . A multilayer film according to  claim 1  wherein the film is oriented in at least one direction.  
     
     
         3 . The multilayer film of  claim 2  wherein the film is biaxially oriented.  
     
     
         4 . A multilayer hollow structure having a sidewall with an inner surface and an outer surface, the sidewall comprising at least a first resin layer and a second resin layer wherein the first resin layer comprises poly(1,3-propylene 2,6-naphthalate) and the second resin layer comprises poly(ethylene terephthalate), and at least a portion of the sidewall is oriented in at least one direction.  
     
     
         5 . The multilayer hollow structure of  claim 4  wherein at least a portion of the sidewall is biaxially oriented.  
     
     
         6 . The multilayer hollow structure of  claim 5  wherein the inner surface comprises the poly(ethylene terephthalate) layer and the outer surface comprises the poly(1,3-propylene 2,6-naphthalate) layer.  
     
     
         7 . The multilayer hollow structure of  claim 4  further comprising a third resin layer comprising poly(ethylene terephthalate) wherein the inner and outer surfaces comprise the poly(ethylene terephthalate) layers and the poly(1,3-propylene 2,6-naphthalate) forms a core layer between the inner and outer poly(ethylene terephthalate) layers.  
     
     
         8 . A process for forming a biaxially oriented multilayer film comprising the steps of: co-extruding at least first and second resin layers wherein the first resin layer comprises substantially amorphous poly(1,3-propylene 2,6-naphthalate) and the second resin layer comprises substantially amorphous poly(ethylene terephthalate); and biaxially stretching the co-extruded film at a temperature of from about 90° C. to about 115° C.  
     
     
         9 . The process of  claim 8  wherein the film is biaxially stretched at a temperature of from about 100° C. to about 110° C.  
     
     
         10 . The process of  claim 9  further comprising the step of heatsetting the film at a temperature of from about 160° C. to about 180° C. after the step of biaxial stretching.  
     
     
         11 . A process for forming a hollow container comprising the steps of: forming a multilayer preform comprising at least a first resin layer and a second resin layer wherein the first resin layer comprises substantially amorphous poly(1,3-propylene 2,6-naphthalate) and the second resin layer comprises substantially amorphous poly(ethylene terephthalate); and blow molding the preform at a temperature of from about 90° C. to about 115° C.