POSITION DEVIATION PREVENTING METHOD FOR LITHOGRAPHIC PRINTING PLATE AND BLOCK COPY SHEET FOR LITHOGRAPHIC PRINTING PLATE

摘要

PROBLEM TO BE SOLVED: To prevent the deviation of position of a lithographic printing plate and use suitably a lithographic printing plate with a substrate formed of a material other than a metal applicable to the multi-color printing or the printing of a number of papers by recessing the back of a lithographic printing plate in compliance with recesses and projections when the recesses and projections of required shape are formed on the surface of a block copy sheet and brought into contact with the lithographic printing plate. SOLUTION: A block copy sheet 31 for adjusting the printing pressure is interposed between the back of a lithographic printing plate and the outer peripheral face of a plate cylinder. Recesses and projections 32 of required shape are formed on the surface of a substrate 31a of the block copy sheet 31, and a bonding layer 33 to be bonded releasably on the plate cylinder is formed on the back of the substrate 31a. The block copy sheet 31 is pressure bonded on the back of the lithographic printing plate, and the recesses and projections 32 on the surface are bitten therein to recess the back of the lithographic printing plate and the bonding layer 33 is bonded on a given position on the plate cylinder. The recesses and projections 32 are formed by a method of fixing fine particles 34 such as a glass harder than the substrate of the lithographic printing plate on the surface of the substrate 31a or the like.