| 摘要 |
PURPOSE:To obtain a magnetic recording medium having excellent heat resistance, durability, etc. by using a binder prepd. by bringing org. diisocyanate, long chain diol having the mol.wt. in a specific range and ester group-contg. diol having the mol.wt. below a specific value into reaction on a non-magnetic base. CONSTITUTION:The magnetic layer contg. the thermoplastic polyurethane resin formed by bringing the polyester diol which has <=500mol.wt. and expressed by formulas I, II, III (R1, R2, R5, R6, R7 are bivalent hydrocarbon groups, R1 is a trivalent hydrocarbon group, R4 is a monovalent hydrocarbon group), the long chain polyester diol, polyether diol, polycarbonate diol, etc. having the mol.wt. within a 500-8,000 range and org. diisocyanate into reaction as a binder for ferromagnetic powder is formed on the non-magnetic base. Solubility in a general- purpose org. solvent is improved by using the diol expressed by formulas I - IIIand good coatability and dryability are obtained even if the concn. of the urethane base is increased. The magnetic recording medium having excellent heat resistance, wear resistance, durability, etc. is obtd.
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