| abstract |
method of making a multilayer ring structure, multilayer ring article and apparatus discloses multilayer film structures having ring profiles, and methods and apparatus for making the disclosed structures. multilayer annular articles have a uniform thickness, at least four layers and comprise overlapping and non-overlapping circumferential areas; the layer structure of the non-overlapping area is folded into the overlapping layer. a method of fabricating the structure includes providing a multilayer flow stream with at least four layers of thermoplastic resinous materials; feeding the multilayer flow stream into an annular matrix distribution pipe to form a multilayer annular flow stream; and removing the annular multilayer flow stream from the annular matrix to form the annular multilayer structure. there is also disclosed an apparatus comprising: a supply block, with an optional layer multiplier, which provides a multilayer flow current comprising at least four layers for the pipe of an annular matrix; and an annular die having at least one distribution pipe that extrudes a multilayer flow stream. |