METHOD OF PRODUCING CARBAMIDE-FORMALDEHYDE RESIN Russian patent published in 2024 - IPC C08G12/12 

FIELD: chemistry.

SUBSTANCE: invention relates to chemical industry, to production of carbamide-formaldehyde resins (CFR), particularly low-toxicity resins, which can be used in woodworking industry. Disclosed is a method of producing carbamide-formaldehyde resin, which consists in preparing a reaction mixture and condensation of formaldehyde and carbamide in an aqueous medium with variable pH while heating, additional condensation with an additional amount of carbamide. Paraformaldehyde is used as formaldehyde. Reaction mixture is prepared by mixing the calculated amount of paraformaldehyde with water, after which it is heated to 80°C, the obtained mixture is brought to pH 7.0–8.5 by adding 10% sodium hydroxide, calculated amount of carbamide is added to obtain initial molar ratio of carbamide to formaldehyde equal to 1:2, condensation is carried out at temperature of 90–92°C for at least 30 minutes, then reducing the pH of the reaction mixture to 5.0–5.2 by adding 20% ammonium chloride, continuing condensation at temperature of 90–92°C to positive sample for coagulation of reaction mixture in water, after which the pH of the reaction mixture is increased to 7.5–8.5 by adding 10 % sodium hydroxide and the temperature of the reaction mixture is reduced to 70–75°C, additional condensation of reaction mixture is carried out by adding a second portion of carbamide to obtain a final molar ratio of carbamide to formaldehyde equal to 1:1.15, held for at least 30 minutes, the reaction mixture is stabilized with 10% sodium hydroxide to pH 7.5–8.0 and cooled.

EFFECT: simplified process of producing carbamide-formaldehyde resin, high accuracy of controlling process parameters and environmental friendliness of production while maintaining the required values for low-toxicity CFR viscosity and amount of dry residue.

1 cl, 2 tbl