PRODUCTION OF THIN-TYPE DISK

PURPOSE:To obtain stably the title thin flexible disk by laminating a resin having a low heat-deflection temp. on one or both surfaces of a heat-resistant sheet directly or through another layer, heating and compressing the resinous layer to transfer a rugged signal to the layer and cooling and curing the resin. CONSTITUTION:A soln. in toluene of polymethyl methacrylate having 85 deg.C heat-deflection temp. and 80000 number average mol.wt. is uniformly coated on a polyimide film 8 having >=300 deg.C heat-deflection temp. and 25mum thickness. The film8 is dried at 100 deg.C to laminate a polymethyl methacrylate layer 7 having about 50mum thickness. A stamper 4 molded from an original disk by electrocasting is fixed to a metallic mold 2, a cushion 5 is fixed to a metallic mold 3 and the laminate is heated and compressed to transfer a rugged signal to the layer 7. The laminate is then cooled and cured. A disk is stamped 6 and the remaining material is wound. By this constitution, a flexible disk having