| 摘要 |
1,207,367. 367. Thermographic processes and apparatus. GAF CORP. Dec. 19, 1967, [Dec.30, 1966], No. 57696/67. Headings G2A and G2C. A thermographic process comprises image-wise reflex exposing to heat a two-composent diazotype material containing a substance which releases water on heating, placing the material between two electrodes with the exposed layer in contact with the cathode, passing a current to electrolyse the water and produce alkali at the cathode which causes image-wise coupling of the diazonium compound and the coupler. The developed material may be fixed by uniform exposure to ultraviolet light. Specified substances which release water on heating are the hydrated salts of lithium metaborate, sodium sulphate, sodium dihydrogen phosphate, borax, sodium alginate and sugar. The invention also comprises a thermographic exposure and development apparatus for the above material comprising a source of infrared radiation, means for exposing the material to the source and means for passing an electrical current through the material using two electrodes and a source of electrical current. The infraradiation source is preferably in a rotating cylinder. As shown, the heat sensitive material C containing diazoium compound, azo coupler and a substance which releases water on heating (either one which contains water of crystallisation or a hygroscopic substance) and original D are placed in slot 9 and are passed round rotating cylinder N containing an infrared source 17 so that material C is reflex exposed. The material C and original D are held in contact with the cylinder by an endless belt 12 and after exposure the original D is separated from the material C by means 20. The material C, bearing a latent water image, passes between rollers 25 and 26, acting as anode and cathode respectively, so that the water is electrolysed and hydrogen is released at cathode 26 creating an alkaline environment and allowing coupling to occur. The material C is now uniformly exposed to ultraviolet light 27 to decompose the remaining diazonium compound and fix the image. |
