초록 ▼

A multilayered structure is described that is useful in making containers, the structure having at least one low gas permeable layer specifically located in the multilayered structure so that there is substantial reduction in the formation of unwanted inclusions formed during coextrusion processes.

A multilayered structure is described that is useful in making containers, the structure having at least one low gas permeable layer specifically located in the multilayered structure so that there is substantial reduction in the formation of unwanted inclusions formed during coextrusion processes. In particular, the structure is a tubular body which comprises a plurality of layers of different polymeric materials united or bonded together, said structure having at least one uncentered layer of low gas permeability, said layer having an average thickness in the range of about 1 to 20 percent of the total thickness of the body. The structure may be readily made by forming a series of melted thermoplastic streams, enveloping the series of melted streams to successively form separate and defined layers one upon the other, and introducing a layer of low gas permeable material into the series proximate the exterior portion of the structure. The low gas permeable material may be polyvinylidene chloride copolymer, poly(vinyl alcohol-coethylene) or acrylonitrile-containing polymers.

대표청구항 ▼

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 possessin

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. 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.