Tanning agents

In a process for the production of tanning-agents, reference is made to (1) a synthetic tanning-agent obtained by sulphonating a -methylnaphthalene and dispersing in the product a liquid resin made by alkaline condensation of two mols. of phenol with one mol. of paraformaldehyde, and (2) a synthetic tanning-agent obtained by dispersing a phenolformaldehyde resin in butylnaphthalene sulphonic acid solution.ALSO:Tanning-agents are obtained by mixing (a) products obtained by sulphonating mixtures of natural resins with phenols, or phenolic esters of natural resins, and eliminating a substantial part of the adhering inorganic electrolytes from the sulphonation products, with (b) synthetic tanning agents containing aromatic residues and -SO3H groups. Suitable components of type (a) are obtainable by the process described in Specification 489,967. Suitable components of type (b) are the sulphonic acids of condensation products obtainable from aromatic compounds such as a phenol, naphthalene or aniline, with a bridge-forming reagent such as an aldehyde, sulphur or sulphur chloride. In the examples: (1) an aqueous solution of a sulphonated product obtained from pine resin and phenol, as described in Specification 489,967, is mixed with a synthetic tanning - agent obtained by sulphonating a -methylnaphthalene and dispersing in the product a liquid resin made by alkaline condensation of two mols. of phenol with one mol. of paraformaldehyde; (2) an ester prepared from colophony and tricresol is sulphonated, and the product is freed from electrolytes as described in Specification 489,967, it is then mixed with a synthetic tanning-agent obtained by dispersing a phenolformaldehyde resin in butynaphthalene sulphonic acid solution; (3) a mixture of liquid Swedish resin and b -naphthol is sulphonated, and the product is washed with sodium chloride solution of 6-7 per cent strength; an aqueous solution of the product is mixed with a synthetic tanning-agent obtained by treating naphthalene sulphonic acid with formaldehyde, and the mixture is evaporated.