PRODUCTION OF MAGNETIC RECORDING MATERIAL

摘要

PURPOSE:To improve homogenization and adhesion of a coated film by coating a hot melt resin incorporated with a magnetic material on the surface of a polyester film in the film forming process prior to completion of the crystal orientation of said film then subjecting the film to a crystallization treatment. CONSTITUTION:A magnetic coating prepd. by dispersing and mixing a magnetic material with a hot-melt resin is coated on a polyester film before the crystal orientation of the film is completed during film forming. Said coating may be made in any position where the first stretching is completed and the crystal orientation of the film is not completed yet after extrusion of the film. The film on which the magnetic coating is spread is subjected to stretching to about 1.5-4.5 times in a transverse or longitudinal direction in an atmosphere kept at about 80-118 deg.C then to a crystal orientation treatment continuously in a high temp. atmosphere of about 120-240 deg.C. The coated film having extremely uniform quality and high adhesion is formed if the magnetic coating is spread on the film particularly in the stage when the uniaxial stretching is completed during the process of forming the polyester film in the above-mentioned way.