| 摘要 |
PROBLEM TO BE SOLVED: To realize high density recording through adequate adjustment in amount of lubricant at the magnetic layer surface in view of improving running stability, running durability and storage characteristic by defining thickness of a magnetic layer and containing the particular carbon black and lubricant to the magnetic layer, back coat layer and protection film. SOLUTION: A magnetic layer 3 is formed in the thickness of 0.3μm or less by dispersing ferro-magnetic powder into the binder in order to prevent distortion of an output waveform when long, short wavelength recordings are conducted adjacently. Moreover, carbon black add lubricant in the particle size of 30nm or less, DBP oil absorbing amount of 100ml/100g or more are contained in the magnetic layer 3, back coat layer 4 and protection film 5 to improve lubricating characteristic and durability of coating film by gradually releasing for a long term the lubricant. With the repeated running of tape, the lubricant is transferred from the magnetic layer 3 to the running section such as deck, etc., and even if lubricant in the magnetic layer 3 is reduced, it is supplemented from the other layers to assure the stable running. Moreover, if grooming is generated due to movement of lubricant to the surface of magnetic layer 3 as a result of long term storage, it is compensated by movement of excessive lubricant.
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