| 摘要 |
PURPOSE:To allow an image to disappear with lapse of time and to effectively keep secrecy of confidential documents, etc., by providing an interlayer made of an alkali-soluble resin between a decoloring layer containing a reducing or oxidizing agent and a two-component type diazo photosensitive layer. CONSTITUTION:Stannous chloride as a reducing agent, methyl cellulose, and fine silica is dissolved or dispersed in water, and this mixture is coated on a support 1, such as white paper, and dried to give a decoloring layer 3. An aqueous alginic acid solution is coated on the layer 3, and dried to form an alkali- soluble interlayer 4. Moreover, a photosensitive layer 5 is formed on the layer 4 by coating a coupling component and a diazo component to complete a two- component type diazo copying material. This material is exposed, and developed with an alkaline organic developing solution consisting of monoethanolamine, ethylene glycol, diethylene glycol, and water by a semidry method. After the image has been formed, the interlayer 4 softens, the oxidizing or reducing agent gradually intrudes from the decoloring layer into the photosensitive layer, and decolors the image. |
