METHOD OF PREPARING CARBAMIDO AND/OR MELAMINOFORMALDEHYDE RESINS Russian patent published in 2000 - IPC

FIELD: chemical industry. SUBSTANCE: described is method of preparing carbamido-and/or melaminoformaldehyde resin by condensation of carbamide and/or melamine with formaldehyde during heating operation in variable acidity medium followed by concentration and additional condensation with additional amount of carbamide and/or melamine. In this case, process is carried out in the presence of modifying agents such as alcohol selected from group consisting of ethylene glycol, furyl alcohol, glycerol and pentaerythtrite and having temperature of higher than 100 C, and starch, alcohol being added prior to concentration stage in amount from 0.5 to 6.0 % based on weight of formaldehyde; starch is added prior to decondensation in amount from 0.5 to 5.0 wt. % based on total amount of carbamide and/or melamine and maintained at 70-90 C for 5-20 minutes, and final molar ratio of carbamide and/or melamine and formaldehyde is regulated within 1:0.95-1.1. EFFECT: high adhesive and technological properties of final resins and lower discharges of monomers into air of working zone in processing final resins. 2 tbl