MAGNETIC RECORDING MEDIUM

• Main Author: SOMEZAWA MASASHI
• Format: Patent
• Language: English
• Published: 03.10.1989
• Subjects: ADHESIVES; CHEMICAL PAINT OR INK REMOVERS; CHEMISTRY; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; CORRECTING FLUIDS; DYES; FILLING PASTES; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; INKS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; PHYSICS; POLISHES; USE OF MATERIALS THEREFOR; WOODSTAINS

PURPOSE:To prevent the elimination of a binder from magnetic powder so that the magnetic powder is improved in dispersibility and is decreased in dislodgement and the electromagnetic conversion characteristics and the durability of a magnetic coated film are improved by using a polyurethane resin having a residual aminocarboxylic acid group in the molecule as the binder of the magnetic layer. CONSTITUTION:The polyurethane resin having the residual aminocarboxylic acid group in the molecule is used as the binder of the magnetic layer 2 which is provided on a nonmagnetic base 1 and consists essentially of the magnetic powder and binder. The residual aminocarboxylic acid group bonds securely to the magnetic powder by multidentate coordination on the surface of the magnetic powder and improves the dispersibility of the magnetic powder having all surface characteristics (neutral, acidic, basic) and the boundary face intensifying property of the magnetic coated film. Since the surface of the magnetic powder having the neutral and acidic surface characteristics and the residual aminocarboxylic acid group are securely adsorbed, the adsorption of various additives such as fatty acid having proton- donating atomic groups to the magnetic powder is prevented. The elimination of the binder from the magnetic powder is thereby prevented and the magnetic powder is improved in the dispersibility and decreased in the dislodgment. In addition, the electromagnetic conversion characteristics and durability are improved.