METHOD FOR PRODUCTION OF UREA-FORMALDEHYDE RESINS Russian patent published in 1999 - IPC

FIELD: polymer production. SUBSTANCE: resins are prepared by condensation of urea with formaldehyde in presence of modification agent in media with variable acidity at heating followed by co-condensation of product thus obtained with additional urea. Method is distinguished by that above-said modification agent is monoetanolamine in amount 0.01-0.02 mole per 1 mole of urea, condensation is conducted until medium pH lowers to 5.0- 5.8 and product with viscosity 21-28 s is formed, and co-condensation is conducted to achieve urea-formaldehyde molar ratio 1:(1.0-1.2). Free formaldehyde level in resins is not superior to 0.04% at viscosity 300-520 MPa and concentration of solid residue is 68-70%. EFFECT: improved consumer's quality. 2 tbl, 4 ex