| 摘要 |
PURPOSE:To improve electromagnetic conversion characteristics, traveling property and long-term storage property by specifying a polyester film concerning to the arithmetical average roughness Ra, extraction amt. of oligomers in methylene chloride at 20 deg.C for 2.5 minutes, and surface crystallinity expressed by the ratio of absorption in 1386 cm<-1> band to 1370 cm<-1> band determined by refractive IR spectroscopy. CONSTITUTION:The film is formed so that it shows the arithmetical average roughness Ra of 10 - 28 nm, <=0.50mug/cm<2> extraction amt. of oligomers in methylene chloride at 20 deg.C for 2.5 minutes, surface crystallinity of >=0.38 expressed by the ratio of absorption band in 1386 cm<-1> band to 1370 cm<-1> band determined by refractive IR spectroscopy. If Ra is lower than the specified value, traveling property of the traveling side of a magnetic tape decreases, which increases friction against various guide pins and causes traveling faults, or causes dropout due to worn particles during traveling is repeated. If the Ra is higher than the specified value, the magnetic surface of a magnetic tape becomes rough to cause bad electromagnetic conversion characteristics. Thereby, by this method, the obtd. medium has excellent storage property, surface abrasion resistance and electromagnetic conversion characteristics at high temp and high humidity for a long time. |
