METHOD OF SYNTHESIS OF CARBAMIDOFORMALDEHYDE OLIGOMERIC ADDITIVE TO CARBAMIDE RESINS Russian patent published in 1995 - IPC

FIELD: chemical technology. SUBSTANCE: at first, carbamide is condensed with formaldehyde at heating at their molar ratio 1:(1.8-2.2), respectively, in the presence of ammonia taken at concentration 0.5-1.5 wt.-% of carbamide up to formation of resin-like oligomeric products of condensation. Then a mixture of sugars and/or intermediate products of their production, and/or lignosulfonates were added to neutralized reaction mixture at the dose 20-45 wt. -% of carbamide. Then additional dose carbamide is added in order to achieve the total ratio of carbamide to formaldehyde in the end product as 1:(0.4-1.0), and condensation is carried out at 55-85 C for 40-80 min. Melamine and/or guanamines (aceto- and benzoguanamines) or phenol and/or its derivatives at concentration 0.02-0.1 mole per 1 mole formaldehyde can be added in the process of condensation. EFFECT: decreased toxicity of splint-slab plates and veneer and swelling in water. 2 cl, 3 tbl