METHOD FOR PREPARING CARBAMIDE-FORMALDEHYDE RESIN

FIELD: organic chemistry, chemical technology. ^ SUBSTANCE: invention relates to technology for preparing carbamide-formaldehyde resins used as binding foam plastic and other composition materials. Carbamide-formaldehyde resins are prepared by condensation of formaldehyde an aqueous solution with carbamide in medium with variable acidity at maintaining temperature 60 C, not below, in the presence of polyhydric alcohol (1.5-2.5 mas. p. per 100 mas. p. p. of carbamide) followed by additional condensation with additional amount of carbamide and addition of ammonia to the final mole ratio carbamide, formaldehyde and ammonia = 1:(1.15-1.45):(0.1-0.15), respectively, and hydroxyl-containing polymer as an aqueous solution (0.5-3.5 mas. p. per 100 mas. p. p. of carbamide). Formaldehyde an aqueous solution is heated to 60-70 C at loading stage, kept for 15-30 min and pH = 3.0-5.0. Before loading carbamide is kept under humidity condition 60-70% for 24 h. Invention provides preparing foam plastic with reduced emission of formaldehyde in the process of its preparing and exploitation. ^ EFFECT: improved preparing method. ^ 3 cl, 2 tbl, 4 ex