METHOD OF PREPARING CARBAMIDOMELAMINO-FORMALDEHYDE RESINS Russian patent published in 1999 - IPC

FIELD: chemical industry, more particularly binders for wood materials. SUBSTANCE: method comprises condensation of carbamide with formaldehyde to foam precondensate and subsequent cocondensation with melamine in varying media on heating. Condensation of carbamide with formaldehyde is carried out in the presence of 0.01- 0.02 moles of monoethanolamine per 1 mole of carbamide, and after stage of cocondensation with melamine, additional condensation with carbamide is carried out to final carbamide to melamine to formaldehyde molar ratios of 1:0.04-0.25:1.0-1.3, respectively. EFFECT: high physico-chemical characteristics of carbamidomelamino- formaldehyde resin based product, e. g. splint slabs and wood-fiber slabs having, EI class of toxicity, higher water resistance (swelling ability is 11.6-13.5% and water absorption is 47-55%), good strength properties ( ultimate bending strength is 22-24 MPa and ultimate shearing strength is 4.1-4.4 MPa). 3 cl, 1 tbl