Process for the preparation of concentrated aqueous solutions of anionic products of melamine/phenol/formaldehyde condensation, solutions obtained and their use as additives for building materials

摘要

Anionic products of melamine/phenol/formaldehyde condensation, containing sulphonic acid groups. The invention relates particularly to a process for the preparation of stable concentrated aqueous solutions of such condensation products, which have a solids content of at least 50 % by weight, which involves a number of successive condensation stages under varied temperature, duration, proportions and pH conditions. The solutions obtained are used especially as additives for mortars.