Cellulosic fibrous materials, e.g. cotton, are protected against climatic influences, especially sunlight, by treating them in the presence of a light-protective pigment with an aqueous impregnation liquor in which a hardenable aminoplast of at least limited solubility in water is dispersed and which contains a reaction accelerator for the aminoplast, mechanically removing excess impregnation liquor and converting the aminoplast in and upon the fibre into the water-insoluble condition without completely drying out the water derived from the impregnation liquor and retained by the fibre until the condensation of the resin is complete, so that the condensation is carried out in the presence of water. Suitable pigments are phthalocyanine pigments, such as copper phthalocyanine or metal-free phthalacyamines, and inorganic pigments such as sienna, chromium oxides, chromium oxide hydrate green (Guignet's green), neutral or basic lead chromate, potassium-barium chromate, cadmium chromates and basic copper carbonate and mixtures thereof, which are preferably applied to the fibrous materials directly as a dispersion in an aqueous emulsion or solution of the hardenable aminoplast. Alternatively the material may be padded in succession with solution of lead acetate and a solution of potassium bichromate to form the pigment in situ or impregnated with an aqueous dispersion of the pigment, dried and then impregnated with a solution or emulsion of the hardenable aminoplast. Suitable hardenable aminoplasts of unlimited or limited solubility in water are produced by condensing formaldehyde with urea, thiourea, guanidine, acetylenediurea, cyanamide, dicyandiamide, biguanide, or aminotriazines, e.g. melamine, melam, melem, formoguanamine, acetoguanamine and benzoguanamine, and alkyl and acyl compounds thereof. Suitable reaction accelerators are hydrochloric, sulphuric and formic acids, salts of strong acids with weak bases, e.g. ammonium p chloride, sulphate, nitrate, oxalate and lactate, and esters of polyhydric alcohols or polybasic acids, e.g. diacetin, monochlorhydrin, glycol diacetate and diethyl tartrate, which hydrolyse at raised temperature to liberate acid, Additional pigment binding agents such as latices of natural and synthetic rubbers or dispersions of flexible and elastic polymerisation products and/or emulsions of hardenable aminoplasts which are insoluble in water and soluble in organic solvents may also be incorporated in the impregnation liquor. Specified polymers are those produced from vinyl esters of organic acids, vinyl alkyl ketones, vinyl halides, vinyl-aryl-compounds, e.g. styrene, esters of acrylic and methacrylic acids with aleohols and phenols, acrylonitrile acrylic, methacrylic, a -chloracrylic, crotonic, maleic and fumaric acid amides and derivatives thereof substituted on the amide nitrogen, acrylic and methacrylic acids, isobutylene, butadiene, 2-chloro-butadiene and vinyl pyridines. Emulsions may contain emulsifying agents and protective colloids, e.g. casein, gelatine and ethylene oxide condensation products of alcohols, acids and amines of high molecular weight. The impregnation liquor preferably contains a quantity of aminoplast such that 5% to 15% of aminoplast is deposited on the material and, after removal of excess impregnation liquor, the material may be stored for from a few minutes to a few days at room temperature or a raised temperature, e.g. 80 DEG C., preferably in a closed vessel, and dried after fixation of the resin. The resin fixation may be carried out by using steam, preferably at temperatures of 110 DEG C.-120 DEG C. under pressure. The material may be rendered water-repellant by subsequent impregnation with a liquor containing a condensation product of hexamethylol melamine, hexamethyl ether, stearic acid, and glycerine distearate in dispersed form, acetic acid and crystalline aluminium sulphate, followed by by drying and hardening at 150 DEG C. for 5 minutes. Cotton fabrics so treated may be used for tent cloth, shop blinds, awnings and deckchair cloth. Specification 733,428 is referred to.
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