Die profile for extruding shallowly ribbed blown thermoplastic film - to facilitate or reduce blocking

摘要

The core land of a die for extrusion of blown thermoplastic film features a series of alternating longitudinal ribs and channels to produce a series of parallel grooves on the inner face of the film. Esp. claimed for producing polyolefin film, but applicable to others, e.g. PVC, acrylic, etc. The superifical grooves facilitate controlled splitting ('fibrillation') to produce fibres alt. for packaging purposes, the reduced contact surface area reduces longitudinal sliding friction during manipulation, and inhibits blocking during storage. Applicable to static or rotary die extrusion systems.