Preparation of granules of dyes, optical whiteners or photoactivators from an aqueous suspension of naphthalene sulfonic acid-formaldehyde condensate dispersant

摘要

Process for the preparation of granules by spray-drying of an aqueous suspension having a solids content of greater than/equal to 30% and containing at least one dye, fluorescent brightener or photoactivator and one condensation product from naphthalenesulfonic acid and formaldehyde and, if necessary, further auxiliaries and/or diluents. The spray-drying is carried out at a feed pressure of 50-150 bar, the residual moisture content of the product is less than 4%, and the granules obtained are in particular very pressure resistant and abrasion resistant.