| 摘要 |
1351795 Anodizing aluminium POLYCHROME CORP 26 April 1971 [3 Aug 1970] 11413/71 Addition to 1235863 Heading C7B A lithographic printing plate comprising an Al supporting base and a light-sensitive coating thereon is made by graining a surface of an Al sheet with a wet mass of hard abrasive particles, anodizing the grained surface to form a hard, dark, steel-grey, lustreless surface, and treating the anodized surface with an undercoating bonding substance prior to coating a lightsensitive composition. The abrasive may be silicate (of Al, K, Na), oxide (of Al, Si) or sulphate (of Mg), e.g. pumice or quartz. Graining may be by machine or hand rubbing using moistened abrasive particles or a slurry or suspension thereof. The Al sheet may be initially degreased and cleaned in NaOH solution. Anodizing may be effected in 8-22% H 2 SO 4 solution at 10-20 volts and C.D. of 10-20 A.S.F. The anodized layer may be sealed.. The undercoating substance may be a solution of alkali metal silicate, silicic acid, alkali metal (e.g. K 2 ) ZrF 6 or H 2 ZrF 6 . The light-sensitive composition may be a condensation product of paraformaldehyde and p-diazo-diphenylamine with tetrahydroxybenzophenone. |
