| 摘要 |
PROBLEM TO BE SOLVED: To obtain a magnetic recording medium which has an excellent traveling property and durability and is adequate for high-density recording by using a magnetic coating material of which the distortion at the time of attaining the equal values in the modulus of storage elasticity and the modulus of loss elasticity attains a specific % or above within a range of specific strain % as a magnetic coating material. SOLUTION: The characteristic that the modulus G' of storage elasticity and the moulus G'' of loss elasticity decrease according to an increase in a strainγis obtd. when the modulus G' of storage elasticity and the modulus G'' of loss elasticity when the magnitude of the strainγis changed in a range of 0.1 to 1000% are examined with the magnetic coating material. The modulus G' of storage elasticity attain the value larger than the modulus G'' of loss elasticity within the range where the strainγis small but when the distortion exceedsγc, the modulus G' of storage elasticity and the mobulus G'' of loss elasticity are inverted and the modulus G'' of loss elasticity attains the value larger than the modulus G' of storage elasticity. When the distortionγc at the time the curves of the moduli G' and G'' of elasticity intersect is regulated to >=50%, the tension in the process of the formation of the coating film and the oscillation of the coating film according to shrinkage are suppressed. Consequently, the surface roughness of the coating film is suppressed and the magnetic recording medium of a double layer constituting type having excellent traveling durability is obtd.
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