| 摘要 |
PURPOSE:To obtain a magnetic recording medium having excellent surface properties, increased maximum residual magnetic flux density and high sensitivity at a high frequency region, by coating a binder containing specific two types of polyvinyl chloride copolymers and rubber substances on a supporter. CONSTITUTION:A magnetic coating material is obtained by dispersing the magnetic power (such as gamma-Fe2O3) to a binder containing (A) a copolymer having >=0.7 OH/CH absorption ratio of the infrared ray absorbing spectrum and obtained by giving the partial saponification to a copolymer of 50-75wt% polyvinyl chloride and 20-40wt% alkyl carboxylic acid vinylester (such as polyvinyl acetate, polyvinyl propionic acid, etc.), (B) a copolymer of 50-80wt% polyvinyl chloride, 20-40wt% alkyl carboxylic acid vinylester, and another 1.5-10wt% monomer (such as maleic acid, acrylic acid, etc.), and (C) rubber substance (acrylonitrile rubber, urethane rubber). This magnetic coating material is coated on a supporter. |
