Thermal digital lithographic printing plate

A positive-working, lithographic printing plate precursor comprising;

• A. a hydrophilic substrate;
• and
• B. a thermally sensitive composite layer structure having an inner surface contiguous to the hydrophilic substrate and an outer oleophilic, ink-receptive surface, the composite layer structure comprising:
• (a) a first layer having the inner surface, the first layer comprising a first polymeric material and photothermal conversion material, wherein the first polymeric material is soluble or dispersible in an aqueous solution, and a solubility inhibiting material which reduces the solubility of the first layer in the aqueous solution;
• and
• (b) a second layer having the outer oleophilic, ink-receptive surface, the second layer comprising a second polymeric material, wherein the second layer is insoluble in the aqueous solution;
• wherein, upon heating the composite layer structure, the heated composite layer structure has an increased rate of removal in the aqueous solution.

A method for forming a planographic printing plate comprising the steps, in the order given:

• I) providing a lithographic printing plate precursor comprising;
• A. a hydrophilic substrate;
• and
• B. a thermally sensitive composite layer structure having an inner surface contiguous to the hydrophilic substrate and an outer oleophilic surface, the composite layer structure comprising:
• (a) a first layer having the inner surface, the first layer comprising a first polymeric material, wherein the first polymeric material is soluble or dispersible in an aqueous solution, and a solubility inhibiting material which reduces the solubility of the first layer in the aqueous solution;
• and
• (b) a second layer having the outer oleophilic surface, the second layer comprising a second polymeric material, wherein the second layer is insoluble in the aqueous solution, and wherein when the first layer is free of photothermal conversion material the second layer is free of photothermal conversion material;
• II) imagewise exposing the composite layer structure to thermal energy to provide exposed portions and complimentary unexposed portions in the composite layer structure, wherein the exposed portions are selectively removable by the aqueous solution;
• and
• III) applying the aqueous solution to the outer oleophilic surface to remove the exposed portions to produce an imaged lithographic printing plate having uncovered hydrophilic areas of the hydrophilic substrate and complimentary ink receptive areas of the outer oleophilic surface.