Process for the preparation of oligomethyleneurea mixtures

摘要

In a process for the preparation of oligomethyleneurea mixtures, formaldehyde solutions and/or methylol group-containing urea/formaldehyde precondensate solutions are added to an initially introduced urea solution. The reaction is carried out in such a way that the total concentration of the reaction components after addition is complete is 50 to 75% by weight, at a urea/formaldehyde molar ratio of 1.1 to 1.6, a temperature of 5 to 50 DEG C and a pH of 2.0 to 4.0 being maintained during the reaction. The addition time is 1 to 6 hours. After the neutralisation of the reaction mixture, this is solidified directly by removal of water.