| 摘要 |
PURPOSE:To prevent the generation of an erroneous optical signal due to surface scratch and to enable clear printing by laminating polyester films A contg. >=0.5wt.% titanium dioxide on both sides of a polyester film B contg. carbon black. CONSTITUTION:Polyester films A contg. >=0.5wt.% titanium dioxide are laminated on both sides of a polyester film B contg. carbon black by such an amt. that the transmissivity of the film is reduced to <=50%, preferably <=1% when the wavelength of rays of light from a light source is 9,000Angstrom . The films A are films stretched in at least one direction, preferably biaxially stretched films. When the resulting base film is used, no erroneous signal is given to an optical signal detecting part even though a magnetic layer or a coated layer of a light shielding material is peeled or scratched by repeated use. Since the surface layers are white because of the titanium dioxide, a clear printed card can be formed by one-side or both-side printing.
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