Inkjet-imageable lithographic printing members and methods of preparing and imaging them

Abstract

Lithographic printing plates are imaged using an inkjet printer to imagewise apply a chemical or masking agent onto the plate surface. In some embodiments, the chemical causes an affinity change, thereby facilitating lithographic printing.

What is claimed is: 
     
         1 - 24 . (canceled) 
     
     
         25 . A method of lithographic printing, the method comprising the steps of:
 (a) providing a printing member comprising a hydrophilic layer having an exposed surface, at least the surface of the layer undergoing a phase change from a hydrophilic state to an oleophilic state in response to an imaging fluid;   (b) dispensing the imaging fluid in an imagewise pattern, the imaging fluid chemically reacting with at least the surface of the layer and inducing the phase change, thereby creating an imagewise lithographic pattern of hydrophilic and oleophilic areas on the printing member;   (c) without developing the printing member to remove portions of the hydrophilic layer, sequentially applying an aqueous fluid and ink to the printing member, whereby the ink adheres only to the oleophilic areas of the printing member; and   (d) transferring the adhered ink from the printing member to a recording medium.   
     
     
         26 . The method of  claim 25 , wherein the top layer comprises a crosslinked hydrophilic polymer. 
     
     
         27 . The method of  claim 26 , wherein the hydrophilic polymer is selected from the group consisting of polyvinyl phosphonic acid, polyvinyl alcohol comprising an amine moiety, and any polymer comprising at least one of a carboxylic acid moiety, a sulfonic acid moiety, and a phosphonic acid moiety. 
     
     
         28 . The method of  claim 25 , wherein the imaging fluid comprises an esterifying agent. 
     
     
         29 . The method of  claim 28 , wherein the esterifying agent is selected from the group consisting of tetramethylammonium hydroxide, phenyltrimethylammonium hydroxide, trimethylsulfonium hydroxide, trimethylsulfoxonium hydroxide, and 1,3-(bistripropylammonium)xylene hydroxide. 
     
     
         30 . The method of  claim 25 , wherein the imaging fluid comprises an alkylating agent. 
     
     
         31 . The method of  claim 25 , wherein the imaging fluid comprises a quaternary ammonium salt. 
     
     
         32 . The method of  claim 25 , wherein the printing member further comprises a hydrophilic substrate beneath the hydrophilic layer.