| 摘要 |
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.
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