METHOD OF SYNTHESIS OF CARBAMIDOFORMALDEHYDE RESIN Russian patent published in 1997 - IPC

FIELD: chemical industry, synthetic polymers. SUBSTANCE: at the first stage of condensation reaction a mixture of carbamide-containing substance is used as carbamide aqueous solution. This mixture is obtained by mixing carbamide and formaldehyde at their mole ratio = (0.8-2.0):1.0 in the presence of alkaline agent containing amino-compound and mixture is subjected for maturation. Obtained aqueous solution of carbamide-containing substance is mixed with formaldehyde at heating up to mole ratio carbamide : formaldehyde = 1.0:(1.75-2.1) and pH = 6.0-8.5; at the second stage condensation reaction of the obtained solution is carried out in acid medium at pH = 3.9-5.1, at 82-98 C followed by cooling and evaporation of condensation product; at the third stage additional portion of carbamide is added to the obtained product up to mole ratio carbamide : formaldehyde = 1.0:(1-2) and condensation is carried out at pH = 7.5-8.5, at 40-65 C followed by resin cooling and stabilizing. EFFECT: low toxicity of resin, enhanced stickiness, decreased net cost and energy. 5 cl, 2 tbl