| 摘要 |
PURPOSE:To enable loading of a flexible magnetic disk to a driving device always without eccentricity by providing a protective layer of a specific thickness formed by curing a compsn. contg. a compd. having a (meth)acrylate bond by radiations on the peripheral edge of the central circular hole of said disk. CONSTITUTION:A radiation polymerizable and curable protective layer 11 consisting of a compd. which has a (meth)acrylate bond in at least one of the molecular principal chain terminal and side chain, of which the number of the ester bond is 1-10 pieces for each 1,000mol.wt. and in which the skeletone of the principal chain is polyester, polyurethane, polyether, polycarbonate, epoxy, etc. or the mixed skeletone thereof is formed to the peripheral edge of the central circular hole 10a of a flexible magnetic disk 10. The thickness of the protective layer is made <=30mu and the surface roughness thereof is made 0.03mu in the average roughness (Ra) of the centerline at cut off 0.25mm.. The friction of the disk 10 with a positioning member is thus decreased and the disk is loaded to the device without eccentricity. The disk having no problem in track accuracy is obtd.
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