METHOD OF PREPARING SYNTHETIC TANNER Russian patent published in 2001 - IPC

FIELD: leather industry. SUBSTANCE: invention relates to production of synthetic tanner used in leather industry when manufacturing sole leather. Tanner is prepared by sulfonation of beta-naphthol on heating followed by condensation of resultant sulfonation mixture with phenol and formaldehyde. Sulfonation mixture first undergoes interaction with synthetic phenol preliminarily diluted with water at 1:1 weight ratio at 55-60 C. After that, formalin is added with velocity 5 l/min at 55-70 C and process is continued at this temperature for 6 h. Mixture is then neutralized with aqueous ammonia with velocity 8-10 l/min at 60-65 C until pH 3.8-4.5 is reached. EFFECT: increased quality index (60-61%).