| 摘要 |
A method to obtain a lithographic printing master comprising: a) an imaginable element is formed from a radiation sensitive coating on a base, said coating comprising: (1) anionic polymer particles; (2) cationic polymer particles; and (3) a converter substance capable of converting radiation into heat; b) the imaginable element forms a hydrophilic layer on a base but it can not be removed by water or fountain used for press after coated and dried; c) image-wise or information-wise exposing to radiation, the hydrophilic imaginable element layer becomes hydrophobic for ink under the action of thermal laser and unexposed area remains hydrophilic for water. The converter substance may be selected to have an absorption spectrum that is optimized to absorb at the wavelength of imaging radiation. The anionic polymer particles have an anionic surface and cationic polymer particles have a cationic surface. The processless lithographic printing precursor so created may be imaged using absorbed radiation that is imagewise converted to heat, resulting in areas of hydrophobic property, while unimaged areas retain their hydrophilic property. This allows the latent image so formed to be employed in creating a negative-working lithographic printing master. The negative-working lithographic printing master so created is irreversible, does not require a substrate of controlled hydrophilicity and provides great toughness in the exposed areas.
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