| 摘要 |
PURPOSE:To improve the durability of a optical disk by making the thickness of the thin film layer of inorganic glass into the range of 500-800Angstrom . CONSTITUTION:The thickness of the thin film layer of the inorganic glass of the high density information recording carrier to form the high density information recording layer through the thin film layer of the inorganic glass on the transparent plastic substrate is 500-800Angstrom . For the inorganic glass, the alkali metal is 1wt% or below by alkali metal oxide conversion, and the quantity of the alkali metal is 0.8wt% or below by the alkali metal oxide conversion. It is preferable that in the non-alkali glass, the silicic acid glass is not contained and for the inorganic glass, further, the alkaline earth metal is contained in the range of 20wt%-35wt% by the alkaline earth metal oxide conversion. It is preferable that the alkaline earth metal oxide is at least one compound or above selected out of the group composed of BaO, CaO, MgO, SrO and BeO, and especially, BaO is main. Thus, the disk with the excellent durability can be obtained.
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