METHOD OF PREPARING CARBAMIDOFORMALDEHYDE RESINS Russian patent published in 2001 - IPC

FIELD: manufacture of heat-insulating glass wool minerals in wood-working industry. SUBSTANCE: synthesis of resins by initial condensation in medium with variable acidity of carbamide with formaldehyde in the presence of catalyst which is hexamethylene tetramine production waste comprising, wt %: hexamethylene tetramine, 50-60; formate-ion, 7-15; formaldehyde, 0.15-0.5; and water, the balance up to 100. Amount of catalyst is 0.07-0.13 mole per mole of carbamide in terms of hexamethylene tetramine, hexamethylene tetramine is added directly after carbamide, and formaldehyde is then added in amount of 2.2-2.4 moles per 1 mole of carbamide. Product is then neutralized with alkali to pH of 8.0-9.0, cooled to 60-70 C, concentrated under vacuum, additional amount of 0.293-0.341 of initial amount of carbamide, and resins are stabilized with aqueous solutions of ammonia or alkali. As obvious from invention, resins are stable during storage, have lower content of formaldehyde and are completely miscible with water. EFFECT: more efficient preparation method. 6 cl, 5 ex, 1 tbl