METHOD OF PRODUCING CARBAMIDE-FORMALDEHYDE RESIN Russian patent published in 2017 - IPC C08G12/12 C08G12/36 

FIELD: chemistry.

SUBSTANCE: process for the production of carbamide-formaldehyde resin by condensation of carbamide and low-methanol carbamide-formaldehyde concentrate in an aqueous medium with variable pH includes several stages. Prior to the condensation in a weakly alkaline carbamide-formaldehyde concentrate is introduced 55% formalin at a ratio of components, wt %: 75-90 wt % carbamide formaldehyde concentrate Formalin 25-10 wt % And allowed to stand at room temperature and stirring for 6 hours at pH 7.3-7.8. After that, carbamide is introduced and a slightly alkaline condensation is carried out at a molar ratio of carbamide to formaldehyde 1: 2, for 0.5 hours at pH 7.1-7.3 and temperature 90°C. The polycondensation step of the reaction mass is carried out in an acidic medium at a pH of 4.7-4.9 and a temperature of 96-98°C to achieve a viscosity of the reaction mass in the range of 100-130 seconds. The pre-condensation of the reaction mass with additional urea input is carried out at a temperature of 70°C and pH 7.5-8.5 to the molar ratio of carbamide to formaldehyde 1: 1.15. Then the finished resin is cooled to a temperature of 20-25°C and packed.

EFFECT: resulting carbamide-formaldehyde resin based on a low-methanol carbamide formaldehyde concentrate with a free formaldehyde content of up to 0,04 percent and methanol to 0,08 percent reduces the emission of formaldehyde from products manufactured with its use.

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