Multilayer tubular body with uncentered barrier layer

Claim 1

A nonflexible thick-walled tubular article with a wall thickness in excess of 0.1 inch having a heat-degradable polyvinylidene barrier layer with a marked decrease in relative volume of entrapped inclusions per given length, said article capable of being biaxially oriented into a container possessing low gas permeability comprising at least three cojoined polymeric layers with at least one intermediate polymeric layer being a polyvinylidene chloride barrier layer, said article being formed by simultaneously coextruding and bonding the polymeric layers together as a series of melted streams with the intermediate polyvinylidene chloride barrier layer being located proximate the exterior surface thereof, the outer polymeric layer being less thick than the article portion within the polyvinylidene chloride barrier layer, and quenching said series of melted streams from the outer exterior surface of said series proximate said polyvinylidene chloride barrier layer, said polyvinylidene chloride barrier layer being located within the outer about one percent to 33 percent of the total thickness and having a thickness of from about 1 percent to about 20 percent of the total thickness of the cojoined, multilayered tubular article.

Claim 10

A method of substantially reducing gaseous inclusions in coextruding a solid nonflexible tubular body having at least three polymeric layers including inner and outer layers of thermoplastic material selected from a group comprising polyolefins, polystyrenes, and polyesters, and an intermediate polyvinylidene chloride barrier layer therein, said body having a wall thickness of about 0.1 inch to about 0.5 inch and being capable of being axially oriented into a container possessing low gas permeability, which comprises forming a series of melted streams of the polymeric materials, enveloping the series of melted streams to form separate and defined cojoined tubular layers one upon the other, and introducing the polyvinylidene chloride barrier layer intermediately within said series and proximate the exterior surface of said tubular layers, said polyvinylidene chloride barrier layer being within the outer 1 percent to 33 percent of the total thickness of the cojoined tubular layers and having a thickness of from about 1 percent to about 20 percent of total thickness of the cojoined tubular layers, and thereafter quenching said series of cojoined tubular layers from their outer exterior surface proximate said barrier layer to form a cojoined multilayered solid thick-walled body.

Claim 11

A method of substantially reducing gaseous inclusions in coextruding a solid nonflexible tubular body having at least three polymeric layers including inner and outer layers of thermoplastic material selected from a group comprising polyolefins, polystyrenes, and polyesters, and an intermediate polyvinylidene chloride barrier layer therein, said body having a wall thickness of about 0.1 inch to about 0.5 inch and being capable of being axially oriented into a container possessing low gas permeability, which comprises forming a series of melted streams of the polymeric materials, enveloping the series of melted streams to form separate and defined cojoined tubular layers one upon the other, and introducing the polyvinylidene chloride barrier layer intermediately within said series and proximate the exterior surface of said tubular layers, said polyvinylidene chloride barrier layer being within the outer 1 percent to 33 percent of the total thickness of the cojoined tubular layers and having a thickness of from about 1 percent to about 20 percent of total thickness of the cojoined tubular layers, and thereafter quenching said series of cojoined tubular layers from their outer exterior surface proximate said barrier layer to form a cojoined multilayered solid thick-walled body.

Claim 15

A method of substantially reducing inclusions in coextruding a thick-walled tubular article having a wall thickness in excess of 0.1 inch with an intermediate layer of polyvinylidene chloride and being adapted to form a thick-walled parison capable of biaxial orientation into a container with low gas permeability, comprising: forming a series of melted streams of a thermoplastic material selected from a group comprising polyolefins, polystyrenes, and polyesters, forming a melted stream of polyvinylidene chloride, forming the melted streams of the thermoplastic material into at least two, thick-walled tubular, coaxial streams with the outer tubular stream being less thick than the inner tubular stream, forming the melted stream of polyvinylidene chloride into a thin-walled tubular stream coaxially arranged with the tubular streams of thermoplastic material and introducing the tubular stream of polyvinylidene chloride intermediately within the melted streams of thermoplastic material so it lies proximate the exterior surface of the cojoined streams, and quenching the cojoined tubular streams of thermoplastic material and polyvinylidene chloride at their exterior surface to reduce the degradation of the polyvinylidende chloride and the formation of entrapped inclusions in the resulting tubular article.

Claim 16

A method of substantially reducing inclusions in coextruding a thick-walled tubular article having a wall thickness in excess of 0.1 inch with an intermediate layer of polyvinylidene chloride and being adapted to form a thick-walled parison capable of biaxial orientation into a container with low gas permeability, comprising: forming a series of melted streams of a thermoplastic material selected from a group comprising polyolefins, polystyrenes, and polyesters, forming a melted stream of polyvinylidene chloride, forming the melted streams of the thermoplastic material into at least two, thick-walled tubular, coaxial streams with the outer tubular stream being less thick than the inner tubular stream, forming the melted stream of polyvinylidene chloride into a thin-walled tubular stream coaxially arranged with the tubular streams of thermoplastic material and introducing the tubular stream of polyvinylidene chloride intermediately within the melted streams of thermoplastic material so it lies proximate the exterior surface of the cojoined streams, and quenching the cojoined tubular streams of thermoplastic material and polyvinylidene chloride at their exterior surface to reduce the degradation of the polyvinylidende chloride and the formation of entrapped inclusions in the resulting tubular article.