| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to adhere optical disk substrates by a double coated tacky adhesive sheet while well maintaining the reproduction characteristic of an optical disk by specifying the surface roughness of the release surface of the separators of the double coated tacky adhesive sheet used for overlap adhesion of the first optical disk substrate and the second optical disk substrate. SOLUTION: The separators 21, 22 specified to <=0.7 μm, more preferably <=0.6 μm in the surface roughness Ra (center line average height) of the release surfaces (the surfaces to be affixed to the tacky adhesive surfaces of the tacky adhesive sheet 1) are affixed to both surfaces of the double coated tacky adhesive sheet 1. As a result, the ruggedness on the surfaces of the double coated tacky adhesive sheet 1 from which the separators 21, 22 are peeled may be formed as ultra-smooth surfaces of <=0.7 μm in the surface roughness Ra. The optical disk substrates are capable of preserving the light reflection characteristic of reflection layers (or recording layers) and warranting good reproduction image quality in spite of the adhesion by the double coated tacky adhesive sheet 1. |
