PROCESS FOR PREPARING UREA-FORMALDEHYDE RESINS Russian patent published in 1996 - IPC

FIELD: furniture industry. SUBSTANCE: urea is condensated with formaldehyde at the initial molar ratio of 1:1.8-1.9 in the presence of 0.010-0.021 mole of hexamethylene tetramine per 1 mole of formaldehyde on heating in medium having variable acidity with the pH changing from 7.0-9.0 to 3.7-4.5 till the reaction mixture reaches viscosity of 60-110 MPa*s followed by concentration till the reaction mixture reaches viscosity of 1600-2600 MPa*s and condensation with additional amount of urea till the urea to formaldehyde final molar ratio of 1:1.1-1.3 is reached to give resin having free formaldehyde content of 0.05- 0.12%, viscosity of 700-1700 MPa*s and high water miscibility. EFFECT: more efficient preparation process. 1 tbl