Patent ID: 7582405

Claim:
A method for preparing an image recording medium, the method comprising: providing a matrix, a radiation absorbing compound, an inorganic acid or salt thereof, and a reactant compound, wherein the inorganic acid or salt thereof is phosphovanadic acids or salts thereof, wherein the reactant compound includes an alpha amino alcohols containing NH 2 C(R1,R2)CH 2 OH, wherein R1 and R2 each is independently selected from the following: hydrogen, aryl, and alkyl groups, wherein the radiation absorbing compound absorbs radiation and initiates a reduction/oxidation reaction between the inorganic acid or salts thereof and the reactant compound to produce a color change; dissolving the radiation absorbing compound, the inorganic acid or salt thereof, and the reactant compound, in the matrix to form a matrix mixture; and disposing the matrix mixture onto a substrate, wherein the layer does not include a color former selected from a leuco dye and a phthalide color former.