PURPOSE: To prevent a silicone rubber layer of a planographic printing plate from peeling due to pressure desensitization in the edge of the original film and to improve contamination resistance of the base and printing durability by crosslinking specified polysiloxane and specified hydrodiene polysiloxane by additional reaction to form the silicone rubber layer.
CONSTITUTION: This waterless photosensitive planographic printing plate has a silicone rubber layer prepared by crosslinking (a) polysiloxane and (b) hydrodiene polysiloxane expressed by formula by additional reaction. The polysiloxane used has at least two alkenyl groups directly bonded to silicon atom in a molecule and is a mixture of 50-95wt.% polysiloxane satisfying 100≤1≤500 and 5-50wt.% polysiloxane satisfying 700≤1≤10000, wherein 1 is the average repetition number of -(Si(R1)(R2)-O)1- group 10 polysiloxane. By using the hydrodiene polysiloxane having high Si-H group ratio in one molecule as above described, the film strength can be increased.
TANAKA YUJI
URABE YOSHIHIKO
HIRANO TSUMORU
OBA TOSHIO
SHINETSU CHEMICAL CO