Patent ID: 7591926

Claim:
A process for the production of nonuniformly intensely colored paper, comprising: a) applying by a printing method at least one surfactant or a mixture of surfactants in the form of a latent image or pattern to paper on a continuous paper web, whereby the surfactant(s) is/are mixed with at least one filler (pigment), selected from oxides of metals or semimetals, or inorganic matters, or organic matters, or combinations thereof; wherein the at least one surfactant or a mixture of surfactants are present in the form of any of solutions, emulsions, and dispersions in a concentration ranging between approximately 0.01 to 30 wt. % on the basis of the total weight of the solutions, emulsions, and dispersions; and wherein a ratio of filler to surfactant in the solutions, emulsions, and dispersions ranges approximately from 1:0.08 to 1:0.9; b) coloring of the paper by means of a dye solution; wherein the dye is present in a concentration ranging between approximately 0.1 to 30 wt. % on the basis of the total weight of the solution; and c) drying of the colored paper.