Feedblock for adjusting the dimensions of a set of co-extruded layers of a multi-layer sheet

摘要

A feedblock for supplying a multi-layer stream of polymeric material to an extrusion die is provided wherein the dimension of at least some of the layers of the multi-layer stream can be precisely adjusted and/or controlled. The feedblock includes a primary flow path which is used to create a first layer and two secondary flow paths which are used to create a set of second and third layers. The secondary flow paths are positioned relative to the primary flow path such that the second and third layers are deposited on opposing sides of the primary layer in a sandwich-like configuration. Each of the secondary flow paths include a contoured slot through which a secondary fluid stream of polymeric material is deposited onto a primary stream of polymeric fluid flowing in the primary flow path. The contoured slot is geometrically shaped such that adjusting the position of the contoured slot alters the shape of the secondary fluid stream as it is deposited onto the primary flow path. A set of heaters disposed within the feedblock are positioned on either side of the combined primary and secondary flow paths adjacent to the exit port of the feedblock and are used to heat the secondary streams thereby altering the flow characteristics of the streams which, in turn, causes a corresponding change in the dimensions and profiles of the secondary fluid streams.