METHOD OF PRODUCING MELAMINE CARBAMIDE FORMALDEHYDE RESIN Russian patent published in 2011 - IPC C08G12/00 C08G12/32 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing melamine carbamide formaldehyde resins used binding material for production of wood chipboard, wood fiber board, plywood, adhesives for gluing wood, components of binding materials for producing heat-insulation materials etc. The method involves condensation of carbamide formaldehyde concentrate with carbamide and melamine while heating in the presence of a pH regulator. First, condensation of carbamide formaldehyde concentrate with carbamide is carried out in a medium with variable acidity with molar ratio of formaldehyde to carbamide equal to 1.9-2.2:1 until obtaining a precondensate with relative viscosity of 15-60 s on viscosimetre VZ-246 with nozzle diameter of 4 mm at temperature 45°C. The obtained precondensate then reacts with an additional portion of carbamide formaldehyde concentrate and melamine in the presence of a pH regulator at temperature 95±2°C for 5-30 minutes and pH 8.5-9.5. Further, the condensation reaction is continued at temperature 80-85°C and pH 8.5-9.5 until obtaining a reaction mass with relative viscosity of 20-40 s on viscosimetre VZ-246 with nozzle diameter of 4 mm at temperature 45°C and followed by condensation of the obtained reaction mass with an additional amount of carbamide at temperature 60±2°C for 35±5 minutes, and then at temperature 40±2°C, followed by cooling the obtained resin to 20-30°C. Molar ratio of formaldehyde to the total number of moles of carbamide and melamine is equal to 1.02-1.50, and the ratio of the number of moles of melamine to the number of moles of carbamide is equal to 0.15-1.15.

EFFECT: obtaining melamine carbamide formaldehyde resins with high content of melamine, with reproducible quality factors and stable during storage.

1 cl, 6 ex, 1 tbl