| 摘要 |
FIELD: chemical industry, wood processing industry. SUBSTANCE: production of desired carbamide-formaldehyde resin is carried out in three steps. At the first step carbamide or carbamide condensate is mixed with formaldehyde till molar ratio of carbamide and formaldehyde is 1.0:1.7-2.2, then condensation within 30-60 min at pH 6.5-9.0 and at 80-98 C takes place. At the second step thus prepared solution is affected by condensation at pH 3.9-5.0 and at 88-96 C to desired viscosity. Thus obtained reaction mass is cooled if it is necessary to 60-85 C and is affected by drying in vacuum. At the third step additional portion of carbamide is added till molar ratio of carbamide and formaldehyde is 1.0:0.95-1.3, additional condensation is carried out within 25-60 min at pH 7.0-8.5 and at 40-65 C. Monohydric or multihydric alcohols (being chosen of butanol, ethylene glycol, glycerin, diethylene glycol, polyethylene glycol, pentaerytritol) are added into reaction mass, the process is carried out at the first or at the second step. Quantity of said alcohols is 0.01-0.20 weight % of mass of monomers. EFFECT: decreases toxicity of desired resin, increases content of dry residue in it, increases stability of desired resin. 11 cl, 2 tbl |
