METHOD OF OBTAINING MELAMINE-CONTAINING CARBAMIDEFORMALDEHYDE RESIN Russian patent published in 2014 - IPC C08G12/40 

FIELD: chemistry.

SUBSTANCE: method of obtaining melamine-containing carbamide formaldehyde resin includes condensation of components in three stages. At the first stage reaction mixture from carbamide formaldehyde concentrate, water and carbamide at molar ratio of carbamide to formaldehyde 1:2.05 is prepared in presence of 40% solution of caustic soda to bring pH to 7.6-8.0. Then, heating of prepared mixture to temperature (80-82)°C and self-heating by exothermal character of reaction to temperature (90-93)°C at pH (7.2-7.8) are performed. Obtained mixture is kept in neutral or alkalescent medium for 20 min after temperature 90°C is achieved at pH (7.0-8.0), and during exposure - pH (6.3-6.7). Then medium pH is reduced to 5.0-5.4 with addition of 20% solution of formic acid. Second stage of condensation process is carried out in acidic medium at pH (5.0-5.4) and temperature (93-98)°C to mixability with water which has temperature 20°C 1:(5-6). Then medium pH is increased to 8.0-8.5 by introduction of triethanolamine and mixture is cooled to temperature (82-85)°C with regulation with triethanolamine pH (8.0-8.5). At third stage water and melamine are loaded simultaneously with regulation with triethanolamine pH (8.0-8.5), kept at temperature (80-85)°C and pH (7.8-8.5). Melamine is dissolved to mixability with water 1:(2-2.5), after that, mixture is cooled to temperature (76-78)°C and then carbamide is additionally introduced to molar ratio of carbamide to formaldehyde 1:(1.13-1.14). The following condensation is carried out for 20 min at temperature (50-52)°C and pH (7.5-8.0) and resin is cooled to temperature (25-30)°C at pH (7.6-8.3). Condensation is finished at molar ratio of carbamide, melamine and formaldehyde 1.0:(0.059-0.068):(1.13-1.15).

EFFECT: invention makes it possible to reduce cost of melamine-containing carbamide formaldehyde resins by reduction of applied quantity of melamine with ensuring required ecological and physical-mechanical characteristics of resins and wood boards with their application.

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