| 摘要 |
PURPOSE:To provide an optical information recording medium having a protective layer which is highly resistant to scratching and moisture by providing a layer consisting of water glass on the surface of a base plate opposite from the recording layer. CONSTITUTION:A transparent plastic plate or sheet of polyethylene terephthalate, polycarbonate, acrylic resin (polymethyl methacrylate, etc.), etc. is used as a plastic base plate. The thickness of the base plate is generally >=0.3mm., more particularly preferably 1.0-1.5mm. and is generally used in the form of a disc. A layer of water glass is provided according to this invention on the surface of the base plate to be formed or already formed with the recording layer on the side opposite from the recording layer. The water glass is a concd. aq. soln. of alkali silicate glass having the compsn. Na2O.nSiO2 (n=2-4) which is coated by, for example, spin coating, etc., on the base plate in the commercially marketed state or after diluting the same with water and is dried. The drying is accomplished preferably at 20-200 deg.C. |
