UREA-FORMALDEHYDE RESIN PRODUCTION PROCESS Russian patent published in 2004 - IPC

FIELD: polymer production. SUBSTANCE: water-soluble urea-formaldehyde resins suitable as binding substances and glues for gluing wood, in manufacture of wood chipboards and heat-insulation materials are prepared via condensation of urea-formaldehyde concentrate with urea introduced portionwise in presence of buffer agent (borax or trisodium phosphate) or aqueous methanol. Condensation is conducted at heating in variable-acidity aqueous solution followed by post-condensation with additional urea and second portion of buffer agent. Viscosity regulator is added in two steps: before the first urea charge in amount 0.5 to 30% and after termination of condensation in the resin cooling step in amount 0.1 to 35% per 100% of urea-formaldehyde concentrate. EFFECT: optimized synthesis conditions, improved quality of resins and enhanced their water-miscibility. 1 tbl, 3 ex