Heat-sensitive imaging element for making positive working printing plates
AssigneeAgfa-Gevaert
InventorsMarc Van Damme, Joan Vermeersch
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Abstract
Heat-sensitive imaging element for making positive working printing plates according to the present invention there is provided a heat-sensitive imaging element for making positive working lithographic printing plates comprising on a lithographic base a layer comprising a polymer, soluble in an aqueous alkaline solution and an IR-radiation sensitive top layer. Upon image-wise exposure the capacity of the aqueous alkaline solution to penetrate and/or solubilize the top layer is changed. Image-wise exposure can be performed with an infrared laser with a short as well as with a long pixel well time. The obtained positive working printing plates have excellent printing properties and an improved infrared sensitivity.
Claims14
A heat sensitive imaging element for making a lithographic printing plate comprising on a lithographic base having a hydrophilic surface;
- a hydrophobic layer un-sensitive to visible and UV light comprising a hydrophobic polymer soluble in an aqueous alkaline solution and
- a top layer having a decreased or increased capacity for being penetrated and/or solubilized by an aqueous alkaline solution comprising a compound sensitive to IR-radiation.
A method for making lithographic printing plates comprising the steps of image-wise exposing a heat-sensitive imaging element comprising on a lithographic base having a hydrophilic surface, an aqueous alkaline soluble layer un-sensitive to visible and UV light comprising a hydrophobic polymer and a top layer comprising an IR-sensitive compound and developing said imaging element.
Dependencies are inferred from the claim text.