PROCESS FOR THE PRODUCTION OF UREA-BASED AMINOPLASTIC AQUEOUS RESINS, FORMOL AND MELANINE, THEIR USE AS GLUES IN THE MANUFACTURE OF MATERIALS DERIVED FROM WOOD, AND THEIR RESULTING WOOD-DERIVED MATERIALS

摘要

Such a resin is prepared with a melamine content in the final resin of 10-40% by weight by condensing urea, formalin and melamine, and adding urea to obtain a molar ratio. Final F / NH 2 of 0.25-0.85. (a) Refluxed for up to 15 min. at pH 7-8.5, an aqueous mixture of urea, formaldehyde and melamine at F / NH 2 = 0.85-1.15; (b) the first condensation step is carried out at pH 5-6, 5 and 70.degree.-100.degree. C., to a degree of condensation corresponding to a 25.degree. C. viscosity whose value depends on the active substance, and the condensation is stopped in bringing the pH to 7-8, and the temperature, to 60-80degC; (c) the second condensation step is carried out by adding formalin, urea and the remaining melamine for an F / NH 2 of 0.6-0.9, and is condensed at pH 8-10 and 70-100 degrees C, up to a degree of condensation corresponding to a 25.degree. C. viscosity whose value depends on the active ingredient, and (d) a post-addition of urea is carried out, the NH.sub.2 groups comprising the moles of urea and melamine. . / P