Continuous Casting of Defect-Free Polymeric Films From Solution
Original Publication Date: 1988-Feb-01
Included in the Prior Art Database: 2005-Feb-14
Commonly-used methods of forming polyimide films, which are not readily melt extrudable, is to cast a solution of the polyimide onto either a mandril, from which it is stripped by peeling, or onto a sheet which is later removed from the film by chemical action. Replication of surface defects and inclusion of release agents in the film are unavoidable problems when using these methods. A method of casting which substantially reduces these defects in the composition of polymeric films is accomplished by a machine utilizing the defect-free surface of clean molten metal to which polymers will not adhere and on which the polymers can float. The method is described in the following. The casting is done in a machine comprised of a tray (tank) of molten metal having three different temperature zones.