Patent ID: 8216771

Claim:
A method for making a lithographic printing plate comprising the steps of: providing a heat-sensitive lithographic printing plate precursor including a support having a hydrophilic surface or which is provided with a hydrophilic layer, and a heat-sensitive coating including an infrared absorbing agent and an alkaline soluble oleophilic resin on the support; image-wise exposing the precursor with IR-radiation or heat; and developing the image-wise exposed precursor with an alkaline developing solution including a compound having at least two onium groups such that the heat-sensitive coating is dissolved in the alkaline developing solution at a higher dissolution rate in areas which are exposed to the IR-radiation or heat than in areas which are not exposed to the IR-radiation or heat; wherein the compound having at least two onium groups has a structure according to Formula I, II, or III: Z a -L-Z b , Formula III; Q is a divalent group when e and f are 0, a trivalent group when the sum of e and f is 1, or a tetravalent group when e and f are both 1; Z a to Z d independently are onium groups; L and L a to L d independently are linking groups selected from the group consisting of an arylene group, an arylene-alkylene group, an oxy-alkylene group, an oxy-arylene group, an oxy-heteroarylene group, and a combination of two or more of these groups; Z x -L x represents a repeating unit wherein Z x and L x represent respectively an onium group and a linking group for each x-value; a, b, c, d, e, and f independently are 0 or 1; x is an integer ranging between 1 and 10; and the precursor includes a compound having a structure according to Formula I, II, or III, and during the developing step, at least a portion of the compound is removed from the precursor.