Dry pre-sensitized azide and silicone rubber containing planographic plates and methods of preparation

Claim 1

A dry presensitized positive-working planographic plate comprising a support having an ink receptive surface and having coated thereon one or two layers of (a) a silicone gum selected from the group consisting of a single package-type silicone gum, a two package-type silicone gum and a mixture thereof, (b) a photosensitive azide compound, (c) a cyclized rubber, and (d) a copolymer of vinylidene chloride and acrylonitrile wherein the molar ratio of vinylidene chloride:acrylonitrile is about 70:30 to 91:9, the uppermost layer, when said planographic plate has two layers, containing at least said components (a) and (b) and the lower layer containing at least said component (c), said components (a), (b), (c) and (d) being in a homogeneous mixture when present in a single layer, and said componets (a), (b) and (d) being present in a homogeneous mixture when present in a single layer, and said components (a) and (b) being present in a homogeneous mixture when present in a single layer, said single package-type silicone gum being a linear compound having repeating units of the following formula: ##EQU18## n = 2 - 2000 wherein R', which can be the same or different, is a monovalent alkyl group, a monovalent aryl group or a cyanoaryl group, said linear compound being terminated by acetyl, oxime, alkyl or amino groups said two package-type silicone gum being a condensation type or an addition type silicone gum, said two package addition reaction type silicone gum being formed from the following reaction (A) ##EQU19## or the following reaction (B) ##EQU20## wherein A and B represent organosiloxane residues and R' is a monovalent alkyl group, a monovalent aryl group or a cyanoaryl group; and the two package-type silicone condensation type gum being formed by the following reaction scheme ##EQU21## wherein R', A, and B are as defined in this claim and R is a 1 to 3 carbon alkyl group, in the case of (a), (b), (c) and (d) being in a single layer, the amounts of (a), (b), (c) and (d) corresponding to the application of a coating at a rate of 3 to 10 g/1000 cm 2 of a mixture prepared by dissolving uniformly in 200 to 400 parts by weight of a solvent 1 to 5 parts by weight of a solution prepared by dissolving 3 grams of (c) in 100 ml of a solvent, 1 to 5 parts by weight of (b), 1 to 2 parts by weight of (d) and 10 to 30 parts by weight of (a), in the case of said planographic plate having two layers, (a), (b), (c) and (d) are present in amounts corresponding to applying the following coatings: A. in the case of a coating of (c) and (d), the application of 1 to 4 g/1000 cm 2 of a mixture of 90 to 95 parts by weight of a solution of (c) and 10 to 15 parts by weight of a solution of (d); B. in the case of a coating of (b) and (a), 3 to 10 g/1000 cm 2 of a mixture of 2 to 5 parts by weight of (b), 2 to 10 parts by weight of a single package-type silicone gum (a) and 15 to 30 parts by weight of a two package-type silicone gum (a) in 300 to 400 parts by weight of solvent; C. in the case of coating containing (a) and (b) and (d), the above formulation B further containing 1 to 3 parts by weight of (d), said silicone gum being vulcanized into silicone rubber after application to said support.