| abstract |
The present invention provides a process for the preparation of a material comprising a substrate on whose surface there is at least one pigment coating consisting of one or more pigments of the formula (I) or (II) or derivatives thereof n n A(D.sub.1)(D.sub.2).sub.x (I) n n n Pc (II) n n in which n A is the radical of a chromophore of the quinacridone, anthraquinone, perylene, indigo, azo, quinophthalone, isoindolinone, isoindoline, dioxazine, phthalocyanine or diketopyrrolopyrrole series which contains nitrogen atoms attached to D 1 and to x D 2 , each nitrogen atom present in A being able independently of the others to be attached to 0, 1 or 2 groups D 1 or D 2 , n D 1 and D 2 are hydrogen, x is an integer from 0 to 4, and n Pc is a chromophore of the phthalocyanine series, n which is applied by n (a) coating the substrate with a solution or melt of at least one latent pigment of the formula (II) or (IV), ##STR1## and (b) converting the latent pigment partially or completely into its insoluble pigment form by eliminating groups D 3 and D 4 , or by eliminating groups L 1 and L 2 . n The invention also relates to a structured material prepared in this way, to its use as a color filter or for the permanent storage of digital information, and to a method of reading out digital information stored thereon by irradiation with a light source and measurement of the intensity of the reflected or transmitted light beam. |