| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyester film for magnetic recording medium which can be used suitably not only for a video tape few in the drop-out but also for a vapor deposition-type magnetic tape for data backup which is low in the error rate. SOLUTION: The polyester film for magnetic recording medium is characterized in that, on the one surface A of the polyester film there exist fine surface protrusions due to fine particles, the particle size of the above fine particles is 5-50 nm, in the one surface A the number of the fine surface protrusions is 3-100 millions/mm<2> , the number of the 50-120 nm high surface protrusions is <=1000/mm<2> , the number of the >120 nm high surface protrusions is <=400/100 cm<2> , and the number of the aggregated, surface-attached substances is <=30/mm<2> .
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