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A coextrusion die for the extrusion of plastics materials in the shape of a tubular film comprising supply means for separately supplying at least two plastics materials to said die, a distribution channel system connected to each supply means, each distribution channel system comprising at least tw

A coextrusion die for the extrusion of plastics materials in the shape of a tubular film comprising supply means for separately supplying at least two plastics materials to said die, a distribution channel system connected to each supply means, each distribution channel system comprising at least two arched channels provided in different axial planes, the ends of each arched channel being connected to the middle portion of the following arched channel and the distribution channel systems being located at different distances from the center axis of the die, collecting chambers communicating with said distribution channel systems and an annular extrusion slot communicating with the collecting chambers.

대표청구항 ▼

An extrusion die for the coextrusion of plural plastic materials into the form of a tubular film, said die comprising: (A) means for separately supplying at least two extrudable plastic materials in a fluid state; (B) a material distribution section comprising an array of annular elements providing

An extrusion die for the coextrusion of plural plastic materials into the form of a tubular film, said die comprising: (A) means for separately supplying at least two extrudable plastic materials in a fluid state; (B) a material distribution section comprising an array of annular elements providing a plurality of pairs of mutually contacting surfaces, at least one of said surfaces of each pair being recessed to define a labyrinthine distribution channel system for each such material, said system having an inlet opening connected to one of said supply means and dividing into opposite generally peripherally extending passages terminating in axially extending connecting passages which in turn divide into opposite peripherally extending passages terminating in axially extending connecting passages which in turn divide into oppositely peripherally extending passages terminating in axially connecting passages, the number of said passage divisions being sufficient to provide an array of at least eight peripherally spaced apart connecting passages for each extrudable material opening generally axially through an end wall of said distribution section, the plural distribution channel systems being arranged in radially displaced relation at different radial distances from the centre axis of the extrusion die; (C) an extrusion die section having one end wall contacting said distribution section end wall and comprising a plurality of concentric generally annular elements having generally spaced parallel concentric surfaces defining a plurality of continuous annular collecting chambers, one for each extrudable material, transition passage means communicating between the open ends of each array of said connecting passages from said distribution secton and the interior end of the corresponding collecting chamber, a common continuous annular extrusion slot axially downstream of said collecting chambers and opening through the opposite end wall of said die section, and delivery passage means merging the ends of the collecting chambers to form a common interior end of said extrusion slot spaced upstream from said slot opening; and (D) mechanical engagement means uniting the annular elements of said distribution and extrusion die sections, respectively, and connecting said sections together with said end faces in contact.