To provide a biaxially oriented polyester film which is excellent in processibility into a sublimation type thermal transfer ribbon and further suitable for making the ribbon which is not creased even in printing at a high speed by a thermal transfer printer and is superior in printability.
The biaxially oriented polyester film for the sublimation type thermal transfer ribbon has properties that the difference (Nx-Ny) between a refractive index (Nx) in the longitudinal direction and a refractive index (Ny) in the lateral direction is 0.00-0.03, that a surface orientation degree (AO) defined by formula (1) expressed by AO=(Nx+Ny)/2-Nz (where Nx is the refractive index in the longitudinal direction, Ny the refractive index in the lateral direction and Nz the refractive index in the direction of thickness, is 0.160-0.170), and that the ten-point average roughness (SRz) of the surface of the film is more than 1,500 to 2,200 nm.
COPYRIGHT: (C)2007,JPO&INPIT
HASHIMOTO YOSHIHARU
MATSUOKA MIKIO
SUMINO HIROSHI
KADA SUKEKI
