| 摘要 |
PURPOSE: To obtain a lithographic printing plate in which ink can be efficiently repelled by setting the water absorption amount of a non-printing element part made of a hydrophilic swelled layer to a specific range and setting the amount of the part to less than the amount of the non-printing element part. CONSTITUTION: In a lithographic printing plate which can be formed of a photosensitive lithographic printing plate original plate using pure water as moistening water without necessity of physical development, the water absorption amount of a non-printing element part made of a hydrophilic swelled layer is set to 1 to 50g/m<2> , and the water absorption amount of a printing element part is set to less than the amount of the non-printing element part. In this case, the thickness of the swelled layer is set to 0.2 to 10g/m<2> , and the water absorption rate of the swelled layer is set to 10 to 2000%. An active light ray is emitted to the surface of the original plate having the swelled layer to generate the difference of the amounts between the element part and the non-printing element part, and the lithographic printing plate in which ink can be efficiently repelled is manufactured. |
