| 摘要 |
PURPOSE:To provide excellent heat resistance, transparency and low hygroscopicity and to allow exact recording and reproducing by using specific thermoplastic arom. polyester as an essential component and confining the double refractions of a perpendicular incident single bus to <60nm. CONSTITUTION:The thermoplastic arom. polyester contg. the constitutional unit expressed by formula I is used as the essential component and the double refractions of the perpendicular incident single bus is <60nm. This polyester resin is obtd. by polycondensation of resorcinol or the reactive deriv. thereof and at least one selected from phthalic acid, telephthalic acid and isophthalic acid or the reactive deriv. thereof and contains the resorcinol as the essential component of diol. The ordinary excellent heat resistance, transparency and low hygroscopicity are obtd. in this way and the exact recording and reproducing are possible as the double refractions are <60nm and the glass transition temp. is above the prescribed temp. |
