Optical brightening of shaped articles of synthetic polyesters and polyamides

摘要

Synthetic linear polyester or polyamide shaped articles e.g fibres and films, are brightened by treating them from aqueous liquors or by means of print pastes with an aqueous dispersion of one or more of p-bis styrylbenzene having the formula (I) derivatives thereof which bear substituents on the benzene rings A, B1 and B2 and which are soluble in water to the extent of less than 1% by weight at 25 DEG C. and then fixing the compounds on the shaped articles at a temperature of 90 DEG -225 DEG C. The substituents on the benzene rings A1, B1 and B2 may be chlorine or bromine atoms or cyano, alkyl, alkoxy, alkyloyloxy, carbalkoxy, alkyl-carbamoyl or dialkylcarbamoyl groups, the alkyl radicals preferably containing up to four carbon atoms. Provided the compounds remain soluble in water to the extent of less than 1% by weight at 25 DEG C. hydroxyl, hydroxyalkyl, amino, alkylamino, carbamoyl and sulphonamide groups may also be substituents. The optical brightening agent may be p applied by the thermosol method on a padding machine as an aqueous dispersion which may contain thickeners, the treatment with the aqueous dispersion being followed by drying and a hot air treatment at 120 DEG -220 DEG C. in the case of polyamide materials and at 120 DEG -200 DEG C. in the case of polyester materials, or a treatment with superheated steam at 100 DEG -140 DEG C. Alternatively a high-temperature exhaustion method in which the material is maintained in the aqueous dispersion in a dyeing machine at a temperature above 100 DEG C. for 30-60 minutes and then dried at 90 DEG -225 DEG C. or an exhaustion method in which the material is introduced into the treatment liquor at 60 DEG -70 DEG C. and the temperature raised to 95 DEG -100 DEG C. for 30-60 minutes may be utilized. The aqueous dispersions may also contain dispersing agents, e.g. soaps, sulphite cellulose waste liquor, polyglycol ethers of fatty alcohols or fatty amines or condensation products of naphthalenesulphonic acids, substituted napthhalenesulphonic acids and formaldehyde, and in the case of polyester materials a carrier, e.g. dichlorobenzene, trichlorobenzene, o-phenylphenol, p-phenylphenol, benzoic acid, the p-chlorophenyl monoether of glycol and esters of benzoic acid. A disperse dye may be included in print pastes. The brightening may be effected in conjunction with chemical bleaching with sodium chlorite.