METHOD OF SYNTHESIS OF CARBAMIDOFORMALDEHYDE RESIN Russian patent published in 2002 - IPC

FIELD: chemical technology. SUBSTANCE: invention relates to a method of synthesis of carbamidoformaldehyde resins used as binding agents for production of composite materials in wood working, building and other branches of industry. Carbamidoformaldehyde resin is synthesized by dissolving carbamide in the solution of formaldehyde and ammonia at the loading stage followed by condensation of urea and formaldehyde in the presence of ammonia at the graduate decrease of pH medium value from alkaline to acidic one, at heating, in molar ratio urea : formaldehyde : ammonia = 1 : (2-2.5) : (0.25-0.4), respectively, and the following neutralization and drying. Carbamide dissolving in the solution of formaldehyde and ammonia is performed at the stage of components loading at t = 5-40 C and a modifying agent is added in the form of sodium tetraborate decahydrate taken in the amount 0.7-1% to 100% of urea and formaldehyde mass at t= 50-70 C followed by keeping for 25-30 min. The synthesized resin shows a nonlinear structure, the enhanced tenacity, fungicide properties and low toxicity. EFFECT: improved method of resin synthesis, improved properties. 2 cl, 1 tbl, 4 ex