Blasenformende und stabilisierende Vorrichtung zum Gebrauch im kontinuierlichen Extrusionsverfahren zur Herstellung von Blasfolien.

摘要

This invention discloses a new bubble forming and stabilizing device for use in a continuous extrusion process for making a blown film and a process for using same. The apparatus comprises a bowl shaped mandrel (14) mounted subsequent to a die (6), the mandrel has an undersurface extending substantially parallel to and spaced from the path of travel of the blown film (8) from the die (6) and the undersurface (40) is contoured to guide a stream of cooling air along its surface between the undersurface and the blown film as the blown film emerges from the die. The apparatus allows for increased production rates and improved physical properties of the forming bubble by creating more efficient heat transfer from the forming bubble to the cooling air stream. The device also provides support for the molten bubble during its most unstable state.