Preparations of pteridine pigments

#The present invention relates to a novel preparation of 2,4,5,7-tetraaminopyrimido[5,4g]pteridine, to a process for the production thereof and to the use thereof for colouring high molecular weight organic material and in the production of printing colorants, printing pastes or printing inks.

#Pteridines, for example including 2,4,5,7-tetraminopyrimido[5,4g]pteridine, and their use as pigments are known. For certain applications, however, especially the colouring of specific plastics, such as polyolefins or PVC, or the use of such pigments as colour components in printing colorants, or inks, that can be used both in printing processes and in inkjet printing processes, it has been found that the commercial preparations available today do not fully meet all requirements, especially in terms of the required dispersibility and the hitherto unsatisfactory colour strength associated therewith.

#There is accordingly a need for new forms or preparations of pteridine pigments that form stable dispersions suitable for use in printing colorants, printing pastes and printing inks or ink-jet inks, that produce tinctorially strong colorations and that exhibit good allround fastness properties, as well as a need for production processes that result in those forms or preparations.

#A suspension of 6.20 g of commercial 2,4,6-triamino-5-nitrosopyrimidine (Chemie Uetikon, Germany), 5.15 g of commercial 2,4-diamino-6-hydroxypyrimidine (Fluka, Switzerland) and 11.52 g of commercial toluene-4-sulfonic acid monohydrate in 110 ml of glacial acetic acid (100%) is stirred for 20 hours at 113° C. The reaction mixture is filtered through a hard-paper filter while it is still hot. The moist filter cake, which contains approximately 31.5% by weight of the pyrimido[5,4-g]pteridine salt of formula VI

#is further processed as indicated in the following Examples.

#200.0 g of the 31.5% filter cake from Example 1 are washed with water and then dispersed in 465 g of water, and 2.92 g of sodium hexametaphosphate (Fluka, Switzerland) and 36.5 g of sorbitan monolaurate (Span 20, Fluka, Switzerland) are added thereto. The conversion to pigment form is brought about by the addition of 67 ml of an aqueous 2M NaOH solution (pH about 12), the mixture being stirred first of all for 30 minutes at room temperature and then for 18 hours at 90° C. After cooling, the suspension is filtered, washed with water until neutral and dried in vacuo at 60° C.