Process for the production of color-stable decors in porcelain firing and a pigment composition suitable for this

摘要

The invention relates to a process for the preparation of decorations which are colour-stable in porcelain firing (glost firing), and to a pigment composition suitable for this purpose. Most pigments are not sufficiently colour-stable in porcelain firing. There is a need for increasing the colour stability of pigments. Inclusion pigments based on sulphides and selenides of heavy metals in an oxide shell or silicate shell, in particular ZrSiO4, give more colour-stable decorations in porcelain firing, if colour-stabilising auxiliaries from the series of Zn compounds, in particular ZnO or zinc-containing glass frits, or compounds of cerium(III) or cerium(IV), especially CeO2, are employed as colour-stabilising auxiliaries in the decoration layer and/or glaze layer. The quantity employed in the decorative layer is, in the case of ZnO and CeO2, in general 5 to 50% by weight, relative to the inclusion pigment. In addition to an inclusion pigment, the pigment composition according to the invention also contains at least one of the said colour-stabilising auxiliaries.