Block copy sheet for lithographic printing plate

Abstract

A block copy sheet for lithographic printing plate to be interposed between a plate cylinder and a lithographic printing plate having a front surface and a back surface, at least the back surface being made of a material other than metals, wherein the block copy sheet have convex portions provided on a surface thereof, the convex portions having a predetermined shape so as to concave the back surface of the lithographic printing plate when pressed against the back surface of the lithographic printing plate, and wherein (1) the convex portions comprises a composite particle having protrusions provided on the surface thereof and having a hardness greater than that of the back surface of the lithographic printing plate and a particle diameter of from 1 μm to 100 μm, or (2) the convex portions comprises non-spherical fillers having an average length of from 1 μm to 200 μm and the contact area of the convex portions and the back surface of the lithographic printing plate is from 0.6% to 3.0% of the area of the back surface of the lithographic printing plate.

Dependencies are inferred from the claim text.