| 摘要 |
<p>AN OBJECT OF THE PRESENT INVENTION IS TO PROVIDE A BIAXIALLY ORIENTED HIGH QUALITY POLYESTER FILM EXCELLENT IN THERMAL DIMENSIONAL STABILITY AND CLARITY AND ALSO EXCELLENT IN PRODUCTIVITY, AND ALSO TO PROVIDE A PRODUCTION PROCESS THEREOF. ANOTHER OBJECT IS TO PROVIDE A BIAXIALLY ORIENTED POLYESTER FILM GREATLY IMPROVED IN THE PRACTICAL PROPERTIES RESPECTED IN VARIOUS APPLICATIONS OF THE POLYESTER FILM, SUCH AS THE RECORDING TRACK SHIFT IN MAGNETIC RECORDING TAPE APPLICATION, CURLING IN MAGNETIC RECORDING CARD APPLICATION, DIMENSIONAL CHANGE DURING PROCESS IN PRINTING PLATE APPLICATION, PRINTING SHIFT IN RIBBON APPLICATION, THERMOSTABILITY IN CAPACITOR APPLICATION, AND PERFORATION SENSITIVITY AND LOW TEMPERATURE CURLING IN HEAT-SENSITIVE MIMEOGRAPH STENCIL APPLICATION. THE OBJECTS OF THE PRESENT INVENTION CAN BE ACHIEVED BY A BIAXIALLY ORIENTED POLYESTER FILM, COMPRISING A POLYESTER (A) MAINLY COMPOSED OF ETHYLENE TEREPHTHALATE AND A POLYETHER IMIDE (B), HAVING A SINGLE GLASS TRANSITION TEMPERATURE, AND HAVING A REFRACTIVE INDEX OF 1.60 TO 1.80 AT LEAST IN EITHER THE MACHINE DIRECTION OR THE TRANSVERSE DIRECTION.</p> |
