Water‐soluble sulfonated amino–formaldehyde resins. IV. Melamine–urea resins: Synthesis and properties

The factors affecting the preparation and the properties of sulfonated melamine urea–for‐maldehyde resins were studied. The resins weresynthesized using a four‐step procedure previously used in preparing sulfonated melamine formaldehyde resins. The melamine–urea resins required higher hydroxymethylation and condensation temperatures as the percentage of urea increased. The molecular weight distribution of the prepared resins revealed the formation of low molecular weight species in increasing amounts with higher percentages of urea. The effectiveness of the prepared resins as dispersants for concrete mixes was found to be lower than the pure melamine resins; however, it was possible to enhance them by raising the ratio of sulfonated groups in the resins.