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Abstract

Apparatus for producing a tubular plastic product, for example film, has a die body with inner and outer die members defining between them an annular space, and a first inlet for feeding a first stream of resin into the annular space. The inner and outer die members define an annular chamber communicating between the first inlet and the annular space. The resin stream from the first resin inlet divides into two substreams which flow in the annular chamber in opposite directions about the longitudinal axis of the annular space and then join. A second inlet downstream of the first inlet feeds a second stream of resin into the annular space and over the weld line of the annular resin stream. The annular resin stream is expressed through an annular orifice to form the tubular film. In another embodiment, a discrete relieved area is provided in one of the inner and outer die members downstream of the inlet and defines a mixing chamber in which the two resin substreams are mixed where they join to form the annular stream of resin so as to avoid forming a distinct weld line where the substreams join.

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First Claim