Extrusion Casting Film
“The production line used to make thermoplastic film conventionally includes a formation section and a wind-up section. In the formation section the polymer is extruded and the film is formed; for poly(ethylene terephthalate) the formation section usually comprises extrusion onto a casting drum, biaxial orientation and heat setting. In the wind-up section the finished film is wound onto reels for despatch. The wind-up section usually comprises a series of rollers for maintaining a suitable tension in the film, a profile gauge and a turret for holding the reel of film being wound and for presenting an empty core to the winding station when the reel being wound is full.” (Benson and Mehta, US Patent 4,038,121; 7/26/1977)
“The process of extruding unsupported film, especially a composite of two or more integral resin layers formed by extruding separate molten streams into a single die assembly in which the streams are combined under pressure before they emerge from the die. Such extrusion-cast composite films possess desired properties on each of the respective sides, e.g., heat-sealability on one side and stiffness on the other side, or different slip levels.” (About.com, Extrusion Casting, 1/16/2011)
Recent US Patents
9/28/2010
7,803,292
Optical film, optical film manufacturing method and optical film manufacturing device
Keki of Konica Minolta Opto, Japan produced an optical film by extruding a melted material including a melted cellulose ester resin from a casting die; forming a film between rollers and winding up the formed film. These films are functional films such as polarizing plate protection films, retardation films and view angle expanding films used in liquid crystal display devices and antireflection films. (RDC 12/7/2010