Abstract: Provided is a method for recovering a polycarbonate resin from a discarded optical disk and/or a recovered optical disk, which has a polycarbonate resin substrate. The following process steps (I) and (II) are applied to a chemically treated product, which is obtained by crushing a discarded optical disk and/or a recovered optical disk, and chemically treating the resulting crushed product. Process step (I): a step containing (a) removing a magnetic metal foreign matter with a magnet, and (b) identifying a colored foreign matter with an optical camera, and removing the colored foreign matter. Process step (II): a step containing detecting the presence of a metal foreign matter with a metal foreign matter detector, and removing a resin containing the metal foreign matter.

Abstract: The present invention relates to a method of removing a layer of material from a synthetic resin or an organic acid ester of cellulose comprising: washing the layer from the substrate with an aqueous alkali solution with a temperature of at least 105° C., and then washing the alkali solution from the substrate. Furthermore, the present invention relates to a pressure vessel used for the above method, comprising a longitudinal cylindrical body having a circular cross-section, an end plate connected to the top of the cylindrical body and an inverted end plate connected to the lower part of the cylindrical body in a manner such that its convex part faces upwards wherein the pressure vessel has a strainer plate and a stirring blade inside the cylindrical body.

Abstract: A process for recovering a support from a photographic film is disclosed. The photographic film comprises the support and an undercoating layer provided thereon. The support is made of cellulose triacetate film base. The undercoating layer contains gelatin and cellulose nitrate. According to the present invention, the process comprises the steps of: (I) treating the photographic film with an aqueous solution of a surfactant; and then (II) treating the photographic film with an aqueous solution of a protease to remove the undercoating layer from the support. The aqueous solution of the protease used at the step of (II) preferably further contains an anionic surfactant. It is also preferred that the process further contains the step of (III) treating the recovered support with an aqueous solution of hydrogen peroxide to bleach the support.