Melamine-urea-formaldehyde resin for plywood with increased water resistance (type Melkol® 4XX)

Urea-melamine-formaldehyde resin is obtained by reacting urea and melamine with formaldehyde in an alkaline environment. The production of the resin is a multi-stage process with a variable temperature-time profile, different molar ratios of substrates, and different pH values. Alkaline metal hydroxides are most commonly used as catalysts. The product obtained can be cured at elevated temperatures with the addition of a polycondensation catalyst. The final product has relatively low viscosity, can be cured at elevated temperatures with the addition of an acid salt-based polycondensation catalyst, and is mainly used as a binder for sealing wood chips and, after the addition of fillers, for the production of plywood with increased water resistance.