PROCESS FOR THE OPTICAL BRIGHTENING OF ORGANIC FIBRE MATERIAL

A process for the non-aqueous optical brightening of organic fibre material, especially fibre material made from cellulose, natural or synthetic polyamide, by the exhaustion method, is disclosed, which comprises treating said fibre material in the solution of at least one optical brightener salt consisting of the anionic radical of an anionic optical brightener and at least one cationic radical of an inorganic or organic base, said organic base being derived from an organic nitrogen compound containing at least one nitrogen atom capable of salt formation, in a solvent mixture consisting of unsubstituted or halogenated hydrocarbon boiling between 50 DEG and 150 DEG C and liquid, water soluble organic solvent boiling below 220 DEG , at a temperature between room temperature and the boiling point of the solvent mixture, optionally under pressure, and finishing the brightened fibre material in the usual manner. By this process, excellent white-effects or brightenings having good fastness properties, such as fastness to dry cleaning and washing, are obtained on said fibre material, without any subsequent heat treatment such as steaming or thermofixing.