WERKWIJZE VOOR DE BEREIDING VAN POEDERVORMIGE CONDENSATEN VAN MELAMINE EN FORMALDEHYDE, ALSMEDE GEVORMDE VOORTBRENGSELEN VERVAARDIGD ONDER TOEPASSING VAN DEZE POEDERS.

摘要

Powders of melamine-formaldehyde condensates which are at least sparingly water-soluble are prepared by spray-drying a condensate solution. The condensate solution is obtained by condensing melamine and formaldehyde in aqueous solution in the presence of 0.01 to 0.1 mol of an alkali metal sulphite, bisulphite, dithionite or (formaldehyde)sulphoxylate, based on the melamine. Secondary amounts of a further formaldehyde-condensable substance may optionally be employed. The powders are suitable as impregnation resins or wood glues.