METHOD OF PRODUCING CARBAMIDOMELAMINOFORMALDEHYDE RESIN Russian patent published in 2013 - IPC C08G12/40 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing carbamidomelaminoformaldehyde resins which can be used in producing binding materials for chipboards and fibreboards, gluing furniture components and plywood. The method involves condensation of a carbamidoformaldehyde concentrate with carbamide, melamine and post-condensation with carbamide in a medium with variable acidity while heating. Condensation is carried out in two steps, followed by acid polycondensation and neutralisation. The first condensation step is carried out at pH=5.6-8.0, temperature 20-40°C for 20-30 minutes with addition of a viscosity regulator. The second condensation step is carried out while bringing the molar ratio of formaldehyde to carbamide to 2.3-1.98, heating to 90-92°C and holding for 10-15 minutes. Acid condensation is carried out at temperature 80-82°C and pH=4.5-5.5 until a persistent cloud forms while adding the reaction mass to cold water. Neutralisation is carried out until the reaction mass achieves pH=9.0-10.0. Condensation with melamine is carried out at temperature 80°C for 30 by bringing the molar ratio of melamine to carbamide to 0.04-0.25. Post-condensation is carried out at temperature 65-70°C for 30 minutes while bringing the molar ratio of formaldehyde to carbamide to 1.1-1.2.

EFFECT: invention enables to optimise the process and reduce content of free formaldehyde in the finished product.

5 cl, 1 tbl, 3 ex