| 摘要 |
PURPOSE:To obtain a printing plate of supeiror rust preventiveness, water retention characteristic, and adhesive power between a bse material and a phtosensitive layer by forming a layer consisting of Cr and Cr oxide on the surface of an iron or steel material, and forming a photosensitive layer contg. a photosensitive diazo compd. on said layer. CONSTITUTION:After the surface of an iron or steel plate is plished, this iron plate as anode is pretreated by using electrolyte contg. CrO3 and nitric acid, after which said pretreated iron plate as cathode is electrolyzed in electrolyte contg. CrO3, Ba(NO3)2, nitric acid, NH4F, etc. at 0--5 deg.C liquid temps., etc., for a few minutes, whereby the coating layer of the construction, wherein it consists of Fe, Cr, O alone or materials bound mutually with these, the rate of Fe is higher the nearer the iron material the surface consists of Cr and oxide Cr, and has diffusion cracks and holes, and crystal Cr is exposed on the surace, is formed on the surface of the iron plate. A photosensitive layer contg. a photosensitive dizo cmpound and resin for binding is formed on said coating layer. The resultant photoreceptor is subjected to image exposure and a developing treatment, whereby the plate for lithographic printing plate which causes less dot oversizing, etc., provides many sheets of superior printed matter and will not rust is obtained. |
