Abstract:
Preparations of optical brighteners, for the whitening of fiber materials and coating mixtures for paper, which contain the solution of a dispersion brightener (a) in such a colourless organic liquid (b) which is immiscible with water, the boiling point of which is above 150*C and in which the brightener exhibits a minimum solubility of 0.3 g per litre at room temperature, with the solution optionally also containing an emulsifier (c); furthermore a process for the whitening of fiber materials and coating mixtures for paper wherein said solutions are applied.