| 摘要 |
547,517. Producing planographic printing. plates. DEHN, F. B. (Toland, W. C.). Feb. 14, 1941, No. 2045. [Class 98 (ii)] [Also in Group XVI] A planographic printing plate comprises a base having a coating of a hydrophilic vinyl compound with which is incorporated filler material, the non-printing areas of the coating being waterreceptive. The base may comprise metals, plastic compositions, paper, &c. The colloid is preferably a polyvinyl alcohol resin but may comprise vinyl acetates, halides, esters, ethers, ketones or alcoholates. The filler may be china clay or calcium carbonate. The water absorbtivity of the colloid may be reduced by the addition thereto of a chromic salt such as ammonium bichromate, or a copper salt such as copper chloride with, if desired, the further addition of ferric chloride or sulphate. |
