Optical whitening compositions and their application

An aqueous dispersion suitable for the brightening of textile materials comprises an optical whitening agent having no sulphonic or other water-solubilizing groups dissolved in a polyethylene or polypropylene wax and dispersed in water with the aid of at least one emulsifying agent. The optical whitening agents having no sulphonic or other water-solubilizing groups may be coumarin derivatives, e.g. b -methyl-umbelliferone, 4-methyl-7-diethylamino coumarin, 4,6-dimethyl-7-methylamino coumarine and derivatives of 3-phenyl-7-ureido coumarin, derivatives of amino naphthalimides, dihydrocollidine, benzthiazole, benzoxazole, benziminazole, oxdiazole, pyrrocolines, pyrimidazole or imidazo-(1,2-a)-pyrimidine, bis-(acylaminoaryl)-furano or triazole derivatives. The dispersion may be prepared by dissolving the whitening agent in the polyethylene or polypropylene wax by heating, forming the hot solution containing at least one cationic or hationic emulsifying agent into a relatively concentrated emulsion with hot water, cooling and diluting with water. Specifications 600,696, 611,510, 623,428, 653,681, 669,590, 722,791, 741,798, 746,046, 786,234, 813,543, 814,249, 823,227, 824,659, 835,892, 835,894, 835,895, 835,896, 835,897 and 835,898 are referred to.ALSO:Cellulosic materials, e.g. cotton, and textile materials of wool, nylon, polyester and polyacrylic fibres or filaments are brightened by treating them with an aqueous dispersion of an optical whitening agent, having no sulphonic or other water-solubilising groups, prepared by dissolving the optical whitening agent in a natural or synthetic wax or fat and forming an aqueous dispersion from this solution, and drying the materials. The optical whitening agents having no sulphonic or other water-solubilising groups may be coumarin derivatives, e.g. b -methyl-umbelliferone, 4-methyl-7- diethylaminocoumarin, 4,6-dimethyl-7-methlyamino-coumarin and derivatives of 3-phenyl-7-ureido coumarin, derivatives of amino-naphthalimides, dihydrocollidine, benzthiazole, benzoxazole, benziminazole, oxdiazole, pyrrocoline, pyrimidazole or imidazo-(1,2-a)-pyrimidine, bis-(acylaminoaryl)-furans or triazole derivatives. The natural and synthetic waxes and fats used may be hydrocarbons, esters, fatty acids, fatty ketones, fatty alcohols or mixtures thereof, those specified being carnauba wax, candililla wax, paraffin wax, petrolatum, lanolin, spermaceti, polyethylene and polypropylene. The whitening agent may be dissolved in the wax or fa