Abstract: Provided is a lithographic printing plate comprising a support substrate having disposed thereon a hydrophilic layer interposed between the substrate and an ink-accepting ablative-absorbing surface layer. The ink-accepting surface layer comprising a one or more polymers and a sensitizer characterized by absorption of laser radiation. The printing plate may also comprise a primer layer underlying the ink-accepting surface layer with an adhesion-promoting agent present in the primer layer. Also provided are methods of preparing such lithographic printing plates, and methods of preparing imaged lithographic printing plates from such lithographic printing plates by imagewise exposure to a laser and a subsequent cleaning step with water or with a cleaning solution.

Abstract: Provided are methods of imaging a wet positive working lithographic printing member comprising the steps of providing a positive working printing member comprising a substrate, a hydrophilic layer, an infrared-absorbing layer, and, optionally, an ink-accepting surface layer; exposing the printing member to infrared layer imaging in an imagewise pattern removing by ablation not greater than 10% by weight, and most preferably none of the infrared-absorbing layer and optional ink-accepting surface layer; and removing with water the laser-exposed areas of the infrared-absorbing layer and optional ink-accepting surface layer to reveal the underlying hydrophilic layer. These methods are advantageous in reducing airborne debris and vapors during laser imaging, in increasing the speed of laser imaging, and in providing excellent cleanability and image quality. The printing member may further comprise a primer layer underlying the infrared-absorbing layer with an adhesion-promoting agent present in the primer layer.

Abstract: Provided is a lithographic printing plate comprising a support substrate having disposed thereon an ablative-absorbing layer and, optionally, a durable, ink-accepting surface layer that is not ablative-absorbing. The ablative-absorbing layer contains a high weight percent of an organic sulfonic acid component. The printing plate may further comprise a hydrophilic polymeric layer interposed between the ablative-absorbing layer and the substrate. The printing plate may also comprise a primer layer underlying the ablative-absorbing layer with an adhesion-promoting agent present in the primer layer. Also provided are methods of preparing such lithographic printing plates, and methods of preparing imaged lithographic printing plates from such lithographic printing plates by imagewise exposure to a laser and a subsequent cleaning step with water or with a cleaning solution.

Abstract: Provided are methods of imaging a wet positive working lithographic printing member comprising the steps of providing a positive working printing member comprising a substrate, a hydrophilic layer, an infrared-absorbing layer, and, optionally, an ink-accepting surface layer; exposing the printing member to infrared radiation in an imagewise pattern removing by ablation greater than 10% by weight, and most preferably none of the infrared-absorbing layer and optional ink-accepting surface layer; and removing with water the laser-exposed areas of the infrared-absorbing layer and optional ink-accepting surface layer to reveal the underlying hydrophilic layer. These methods are advantageous in reducing airborne debris and vapors during laser imaging, in increasing the speed of laser imaging, and in providing excellent cleanability and image quality. The printing member may further comprise a primer layer underlying the infrared-absorbing layer with an adhesion-promoting agent present in the primer layer.

Abstract: Provided is a positive working, wet lithographic printing member comprising a hydrophilic metal substrate having disposed thereon a hydrophilic layer, an ablative-absorbing, ink-accepting surface layer and, optionally, an ink-accepting overcoat layer that is not ablative-absorbing. Also provided are methods of preparing such lithographic printing plates, and methods of preparing imaged lithographic printing plates from such lithographic printing plates by imagewise exposure to a laser and a subsequent cleaning step to remove residual laser-induced debris and damaged areas from the hydrophilic layer.