| 摘要 |
PROBLEM TO BE SOLVED: To improve processability and handleability by specifying wet expansion coefficient, whiteness, surface roughness and specific gravity of a biaxially oriented polyester film, thereby sufficiently setting printing density, eliminating curl, and performing excellent printing properties. SOLUTION: A biaxially oriented polyester film has its wet expansion coefficient of 18×10<-3> cm/cm/%R.H. Thus, its curl is eliminated. And, whiteness of the film is necessary in range of 60 to 130% in printing quality. Surface roughness of the film is in a range of 0.001 to 0.25μm in printing quality and processability or particularly preferable roughness is in a range of 0.01 to 0.08μm. Specific gravity of the film is necessary in a range of 1.35 to 0.6 in printing density and mechanical strength, and lowered as compared with that of normal polyester film. At least one surface of the film is coated with aqueous paint as the film for the image receiving base material. |
