| 摘要 |
PURPOSE:To improve the electromagnetic transducing characteristic and wear resistance of the title medium by primarily dispersing a magnetic substance with the polyurethane resin incorporated with a hydrophilic group, then secondarily dispersing the substance with nitrocellulose to obtain a magnetic paint, and then coating the magnetic paint on a nonmagnetic supporting body to form the magnetic layer. CONSTITUTION:A magnetic substance is primarily dispersed with the polyurethane resin incorporated with a hydrophilic group, and then secondarily dispersed with nitrocellulose to obtain a magnetic paint. The paint is coated on a nonmagnetic supporting body along with a binder to form a magnetic layer. Iron oxide, Co-coated iron oxide, iron nitride, etc., can be exemplified as the magnetic substance, and the BET specific surface is controlled to >=30m<2>/g. The binder is the polyurethane resin incorporated with a hydrophilic group, and has a phosphoric group or a sulfonic group or the metal salt of the group in the molecule. Nitrocellulose resin, the nitrocellulose resin having a phosphoric group or a sulfonic group in the molecule as the hydrophilic group, etc., can be used as the nitrocellulose, and lecithin, oleic acid, etc., are used as the dispersant. By this method, the electromagnetic transducing characteristic and durability are improved.
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