METHOD FOR PRODUCTION OF CARBAMIDE-FORMALDEHYDE RESIN Russian patent published in 1998 - IPC

FIELD: production of carbamide-formaldehyde resin. SUBSTANCE: resin is prepared with the help of multistage process. Initially (within two or more stages) aqueous formaldehyde solution is affected by neutralization. The process is followed by condensation of carbamide and formaldehyde which takes place by heating in the medium with alternative acidity. Then vacuum drying is carried out, hydroxyl-containing polymer as aqueous solution is added and then stepped condensation (within three and more stages) takes place, aqueous ammonia solution being added at the final stage till ratio of carbamide, formaldehyde and ammonia is 1:1.21-1.60:0.1-0.15, respectively. Thus prepared carbamide-formaldehyde resin has no polyoxymethylene content. EFFECT: decreased carbamide and formaldehyde content in resin. 3 cl, 1 tbl