| 摘要 |
PROBLEM TO BE SOLVED: To improve the slipperiness between media without the impairment of their performance and appearance and to improve the printing grade of individual information by a thermal transfer printer to a rear surface by specifying the length, max. amplitude, average roughness and density of very small linear ruggedness formed on a front surface reverse from an incident surface of recording and reproducing light to values of respectively specific ranges. SOLUTION: A protective substrate 4 of an optical card is provided with a printing layer 12 having security information by printing on its front surface and is laminated with a transparent front surface layer 5 thereon. The card rear surface 6 on the front surface of the front surface layer 5 is subjected to a surface roughening treatment so as to have the very small linear ruggedness. The length of the very small linear ruggedness is 5 to 85 mm and the max. amplitude of the ruggedness is <=4000 Å, the average roughness Ra is 200 to 1000 Å and the density of the ruggedness is >=20 pieces/mm<2> . The optical is effective when the front surface having the linear ruggedness is printed with personal information by a thermal transfer printer. |
