Phenol-formaldehyde condensates, their preparation and their use as dispersing agents, liquefaction agents and tanning agents

摘要

Polycondensates of phenols and formaldehyde which contain sulphonic acid groups and salts thereof bonded to the phenol either directly or via a methylene bridge are prepared by reacting a neutralized reaction product of phenols and sulphonating agents, which contains a mixture of the starting phenol, phenolsulphonic acid and bis-(hydroxyphenyl) sulphones, with formaldehyde and a bisulphite at a pH value of 4-8.