HAERTUNGSMITTEL FUER AMINOPLASTHARZE

摘要

Aqueous effluents whose relative density at 30 DEG C is adjusted between 1.130 and 1.030, originating from the manufacture of phthalic anhydride by catalytic oxidation of ortho-xylene or naphthalene are neutralised to a pH of between 4.50 and 5.40. The hardener obtained can be employed in a proportion of 1.5 to 15 % by weight relative to the weight of solids content of the aminoplastic resin used. This manufacture of hardener makes it possible to reclaim aqueous residues the removal of which is tricky because of pollution hazards.