| 摘要 |
PROBLEM TO BE SOLVED: To obtain a photosensitive planographic printing master plate having high ink repelling property for which pure water can be used as a dampening water by using a hydrophilic polymer essentially comprising silicone. SOLUTION: This master plate has a hydrophilic swellable layer on a substrate, and the hydrophilic swellable layer has a phase separation structure of at least two phases comprising a phase essentially comprising a hydrophilic polymer and a phase essentially comprising a hydrophobic polymer. The hydrophobic polymer essentially consists of silicone. Silicone is preferable because the hydrophilic swellable layer has both of proper swelling property with water and printing durability and silicone has rubber elasticity, ink repelling property and an effect to form a proper phase separation structure of the hydrophilic polymer. Silicone means a well-known org. silicon compd. which has siloxane bonds in a part or whole of the skeleton and org. groups directly bonded to the silicon atoms. Silicone oil, silicone rubber, silicone resin, and silicone powder can be preferably used. |
