Blue colour filters with enhanced contrast

Abstract

The invention relates to a process for enhancing the contrast of color filters comprising α copper phthalocyanine or ε copper phthalocyanine, wherein a 1,4-diamino-anthraquinone dye or 1,9-annellated derivative thereof, of which the most bathochromic solution absorption peak in the visible spectrum is at from 575 to 615 nm, preferably at from 585 to 605 nm (as compared with around 630 nm for usual 1,4-diamino-anthraquinone dyes or 1,9-annellated derivatives thereof) is used in combination with α copper phthalocyanine or ε copper phthalocyanine. Also claimed are color filters comprising such 1,4-diamino-anthraquinone dyes or 1,9-annellated derivatives thereof, as well as a novel compound of Formula (II), wherein Ris halogen, phenyl, benzyl or C-Calkyl and Ris H, Ris H and Ris C-Calkyl, or Rand Rare both H; Ris H, halogen, C-Calkyl or SONRR; R, Rand Rare each independently from the others halogen or C-Calkyl; and Ris independently from RSONRR, with the proviso that at least one of Rand Ris SONRR, and two radicals of Formula (II) can optionally be linked together via a direct bond or a group —O—, —S—, —NR—, —CO—, —CO—, —CONR— or —CO— connecting together each a substituent R, R, R, R, R, Rand Rfrom both radicals of formula (II).