| 摘要 |
PURPOSE:To enhance raw stock stability of the diazo copying material of which a copied image disappears with lapse of time, by adding an alkali-soluble resin into a precoat layer and a di--tetra-valent metal salt into a photosensitive layer. CONSTITUTION:A precoat layer containing an organic or inorganic reducing or oxidizing agent, e.g., stannous chloride and partial sodium alginate is coated on a substrate and dried. A photosensitive layer containing a salt of a di--tetra- valent metal, such as calcium chloride, a diazo compound, and when needed, a binder, a raw stock stabilizer, such as citric acid, an antioxidant, a dissolving agent, a coating performance-improving agent, an image density-enhancing agent, etc. is formed on the precoat layer. When it is kept acidic during raw storage, said metallic salt reacts with said alkali-soluble resin to harden the precoat layer, preventing the oxidizing or reducing agent from moving to the photosensitive layer. When it is kept alkaline, its movement is started, and an image gradually disappears. |
