| 摘要 |
PURPOSE:To improve the dispersibility of magnetic powder into a binder and to obtain a recording medium having excellent running durability by specifying the mol.wt. of a high-molecular polymer to be used for the binder. CONSTITUTION:The binder is selected from a group of a vinyl chloride system and urethane resin and the weight average mol.wt. thereof is specified to 20,000-80,000. The content of the binder having <=3,000mol.wt. is confined to <=3wt.%. powder of a magnetic alloy having >=40m<2>/g specific surface area is used for a ferromagnetic material. Particularly -SO2M, -OSO3M, -COOM, -OPO(OM1)(OM2), -PO(OM1)(OM2) are incorporated at 1-50X10<-6>equiv./g into the binder and further, a polyisocyanate compd. is incorporated therein. M, M1, M2 is respective substituents are H, alkali metal atoms or -NR1R2R3R4 (where R1-R4 are H, alkyl group of 1-12C, alkenyl group, substd. alkyl group or substd. alkenyl group). The durability and surface characteristic in particular are improved if the magnetic recording medium is produced by using the binder constituted in such a manner.
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