A heat-sensitive lithographic printing plate of the present invention, which enables image recording by infrared-ray scanning exposure based on digital data and has excellent on-press developability, high resistance to scumming and a long press life, the heat-sensitive lithographic printing plate having on a support with a hydrophilic surface an image-forming layer made up of microcapsules in which a reactive group-containing hydrophobic compound is enclosed, a light-to-heat converting agent and a water-soluble compound which has a reactive group capable of reacting with the hydrophobic compound and is situated outside the microcapsules.

A heat-sensitive lithographic printing plate of the present invention, which enables image recording by infrared-ray scanning exposure based on digital data and has excellent on-press developability, high resistance to scumming and a long press life, the heat-sensitive lithographic printing plate having on a support with a hydrophilic surface an image-forming layer made up of microcapsules in which a reactive group-containing hydrophobic compound is enclosed, a light-to-heat converting agent and a water-soluble compound which has a reactive group capable of reacting with the hydrophobic compound and is situated outside the microcapsules.

Disclosed is a printing plate material comprising a support and provided thereon, a hydrophilic layer and a thermosensitive image formation layer containing a blocked isocyanate compound, which is a reaction product of an isocyanate compound, a polyol, and an isocyanate group-blocking material, wherein the thermosensitive image formation layer is formed by coating on the support an aqueous thermosensitive image formation layer coating liquid containing the blocked isocyanate compound.

Polymer materials are described that undergo a two-level three-dimensional crosslinking process. During this process, hydrophilic polymers are crosslinked at two levels, the first results in a low level of crosslinking which leads to a toughening of the layer preventing dissolution by the fountain solution but with the layer remaining hydrophilic. The second level of crosslinking is higher and is the result of exposure to a laser diode thermal imaging device. The crosslinking at this second level results in a loss of hydrophilicity and provides instead an oleophilic image capable of accepting and transferring oil-based ink. The polymer materials are particularly useful in lithographic printing systems where they may used in articles such as a printing plate comprising a substrate having coated thereon a layer that becomes less hydrophilic upon exposure to thermal energy (e.g., heat applied by a laser, other collimated light, or thermal printhead) that effects crosslinking (initial crosslinking or increased crosslinking) in the layer, the layer comprising a mixture of a crosslinked polymer and a thermally active crosslinking metal compound. The invention also provides an overcoat layer eluable in aqueous media for a printing plate precursor comprising on a substrate a layer comprising a mixture of a crosslinked polymer and a thermally active crosslinking metal compound. The overcoat layer protects the heat-sensitive crosslinked polymer layer from discoloration, contamination and scratching and reduces odor and particulate emissions.