Method and coextrusion blowing head for manufacturing multilayered blown films

摘要

Multilayer films are produced by the blown film method, comprising producing a nine-layer film by combining at least two melt streams and at most three melt streams at each of combining locations in a blowing head. An independent claim is also included for a coextrusion blowing head for performing the inventive method, comprising a base plate (25), and ten concentric rings (11-18, 23, 24) defining nine melt channels for the nine individual melt streams. At least two of the concentric rings are respectively receiving at least one other of the rings, and the supporting rings support the at least one other of the rings being arranged on the base plate.