| 摘要 |
1,221,342. Moulding plastics substances. XEROX CORP. 20 Feb., 1968 [11 Sept., 1967], No. 8149/68. Heading B5A. [Also in Division G2] A method of making replicas of a surface deformation image comprises the steps of (a) forming a first generation negative master by applying a layer of hardenable material against the surface deformation image, hardening said layer and stripping it from said surface and (b) forming a second generation positive replica by casting a liquefied film forming material against the negative master and transferring the cast replica to a support member. The hardenable material, which must be inert to the deformation image surface is preferably a curable silicone rubber or may be a low melting point alloy, gelatine or polyvinyl alcohol. The film forming material is a plastics dissolved in a solvent, e.g. polystyrene in toluene, polymethyl methacrylate in methyl ethyl ketone or ethylene dichloride, or cellulose acetate butyrate in ethyl acetate. The surface deformation image may be formed as a frost or relief image, or preferably as a phase hologram, or a deformable, insulating, thermoplastics layer. A negative metal master may be prepared by spraying silver on to the second generation replica, electroplating the silver layer with nickel to form a supporting layer, and withdrawing the metal layers from the cast replica. This master may be used as a short run stamper, or its surface may be passivated chemically and a positive nickel replica formed thereon by electroplating. This nickel master may be used for long run hot stamping of preheated thermoplastics e.g. cellulose acetate films, the preheating temperature being about 200‹ F., the stamping pressure 400-6000 psig, the stamping master temperature 120-300‹ F., and the pressing time 1-10 seconds. |
