| 摘要 |
PROBLEM TO BE SOLVED: To attain stable travelling of a tape by interposing a sheet, in which the impregnation quantity of an antistatic agent is in a specific range, between one inner wall surface of upper/lower halves and a magnetic tape wound on a take-up hub, and thereby preventing the antistatic agent from transferring to the magnetic tape. SOLUTION: An upper and lower sheets 30, 32 hold and protect a magnetic tape 18 as well as smoothing rotation by lowering sliding resistance at the time of rotation of a take-up hub 16. Also, as necessary, shaped parts 30b, 32b are formed that support the take-up hub 16. With the upper and lower sheets 30, 32 made porous, the lower sheet 32 is impregnated with an antistatic agent 40 containing for example quaternary ammonium salt. The solid component of this antistatic agent 40 is prepared as 2.0×10-5 to 1.5×10-4 mg/mm2, increasing surface electrical resistance of the lower sheet 32. This prevents dust from sticking and also prevents the antistatic agent 40 impregnated in the lower sheet 32 from transferring to the magnetic tape 16, when the magnetic tape cassette is transferred, stored and used under a high temperature and high humidity.
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