| 摘要 |
<p>The present invention provide a biaxially oriented polyester film for use in a floppy disc, which has a coefficient of thermal expansion ( alpha T) in film plane of (1.0 +/- 0.5)x10<-><5>mm/mm/ DEG C and a heat shrinkage of not higher than 0.09% alter treating the film for 72 hours under conditions of a temperature of 60 DEG C and a humidity of 80%RH in any directions in film plane, and simultaneously satisfies the following equations (1) to(5): 1.490 </= n alpha </= 1.500 (1) 0.155 </= DELTA P </= 0.168 (2) 1.600 </= n </= 1.603 (3) 40 </= X100 </= 60 (4) 1.385 </= rho </= 1400 (5) wherein n alpha represents a refractive index in film thickness direction, DELTA P represents a degree of planar orientation, n represents an average refractive index, X100 represents a crystal size ( ANGSTROM ) of (110) face, and rho represents a density (g/cm<3>). The biaxially oriented polyester film of the present invention has excellent dimensional stability and flatness and is suitable for use as the base film of floppy disc.</p> |
| 申请人 |
DIAFOIL HOECHST CO., LTD., TOKIO/TOKYO, JP |
发明人 |
TOMITAKA, KICHINOJO, YOKOHAMA-SHI, KANAGAWA-KEN, JP;KOIZUMI, MASUMI, KAWASAKI-SHI, KANAGAWA-KEN, JP |
