| 摘要 |
PURPOSE:To improve the affinity of a binder to magnetic powder and the viscosity characteristic of the binder and to improve durability by using a polyurethane/urea resin into the molecule of which -COOM and other specific polar groups are introduced as the binder. CONSTITUTION:The polyurethane/urea resin having at least one kind of the -SO3M group, -OSO3M group and -PO(OM')2 group as well as the -COOM group (M is H atom or alkali metal atom, M' is H atom, alkali metal atom, hydrocarbon group) is incorporated into the binder of a magnetic recording medium. The binder, therefore, exhibits the high affinity to the magnetic powder and has the good dispersibility even in the magnetic powder which is pulverized to hyper-fine particles or the magnetic powder having a large quantity of magnetization. Since the polyurethane/urea resin used for the binder has excellent heat resistance and tackiness, the thermal characteristics, blocking resistance and durability of the magnetic layer are greatly improved.
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