METHOD OF PREPARING CARBAMIDO-FORMALDEHYDE FILLER Russian patent published in 2000 - IPC

FIELD: chemical industry. SUBSTANCE: described is method of preparing carbamidoformaldehyde polymer which includes finely dispersed particles of cross-linked carbamidoformaldehyde polymer which are used as white synthetic fillers for polymers, paper and paint materials. Carbamide is reacted with carbamidoformaldehyde concentrate containing 54-60 wt.% of formaldehyde, 20-24 wt.% of carbamide and up to 100 wt.% of aqueous phase balance comprising branched oligomer in the presence of phosphoric acid. Reaction is carried out at elevated temperature. The resulting suspension is then neutralized with mixture of chalk and stillage residue resulting from distillation of monoethanol amine spent during purification of gas being converted from carbon dioxide in ammonia production. After separation of deposit, filtrate is recycled into process for partial substitution of water. Chalk to stillage reside weight ratio is 5:1-1:5, industrial of natural chalk is used, and desalted water is used for producing aqueous medium. EFFECT: increased yield of the desired product, reduced oil absorption and lower price of the product. 4 cl, 12 ex, 3 tbl