GB496898A - Process for the manufacture of tanning agents - Google Patents

Abstract

In the manufacture of tanning-agents by treating a ligninsulphonic acid compound, e.g. sulphite cellulose lye, with a condensation product derived from an aromatic hydroxy compound and an agent known to be capable of linking aromatic nuclei, products of improved properties are obtained by splitting off a substantial proportion of sulphurous acid from the ligninsulphonic acid compound by heating it with an aqueous alkali at atmospheric or raised pressure but under such conditions that the formation of water-insoluble compounds is avoided. This treatment of the ligninsulphonic acid compound may be effected before or after its admixture with the condensation product of the aromatic hydroxy compound. Formaldehyde also may be added to the mixture. In the examples: (1) sulphite cellulose lye which has been heated with caustic soda solution is mixed with a phenol-formaldehyde condensation product prepared in the presence of hydrochloric acid; (2) sulphite cellulose lye which has been heated with aqueous ammonia is mixed with a resin prepared from phenol and chloracetone; (3) sulphite lye pretreated as in example 1 is mixed with a resin prepared from crude cresol and a , b -dichlorodiethyl ether, or (example 4) with a resin prepared from phenol and sulphur monochloride, or (example 5) with 4 : 41-dioxydiphenylsulphone and formaldehyde, or (example 6) with formaldehyde and the phenol-formaldehyde of example 1, or (example 7) with a resin prepared from crude cresol and formaldehyde in the presence of hydrochloric acid; (8) sulphite cellulose lye pretreated as in example 1 is mixed with formaldehyde and a resin prepared from crude cresol, phenol and formaldehyde; (9) sulphite cellulose lye pretreated as in example 1 is mixed with a resin prepared from crude cresol and formaldehyde in the presence of hydrochloric acid, and the product is washed with ammonium-sulphate solution; an aqueous solution of the product is mixed with a product obtained by sulphonating a condensation product prepared from phenol, crude cresol and formaldehyde in the presence of hydrochloric acid, and the whole mixture is treated with formaldehyde; (10) sulphite cellulose lye pretreated as in example 1 is mixed with a resin prepared from phenol, glucose and hydrochloric acid; (11) and (12) sulphite cellulose lye pretreated as in example 1 is mixed with the phenol formaldehyde resin of example 1, and the product is acidified with sulphuric acid to yield a solid layer containing a water-soluble tanning-agent; (13) sulphite cellulose lye is mixed with a resin prepared from crude cresol and formaldehyde, and the mixture is heated with caustic soda and then acidified with sulphuric acid. Thickened or ash-free sulphite cellulose lye may be used. The use of phenol-sulphur condensation products and sulphonated phenolic condensation products is mentioned. Specifications 443,967 and 467,998 are referred to.