| 摘要 |
PROBLEM TO BE SOLVED: To provide a white polyester film excellent in film forming properties, and light weight, as well as whiteness, crease resistance upon folding, and printing properties. SOLUTION: This white polyester film is composed of a polyester with a melting point Tm, containing thermoplastic resins (I-1) and (I-2) therein that are incompatible with the polyester, and containing fine gas bubbles inside. The melt viscosities MI(1) and MI(2) of the thermoplastic resins (I-1) and (I-2) at a melting temperature (Tm+20 to Tm+30 deg.C), and a shear rate of 200 s<-1> satisfy, respectively, specific relationships.
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