About Urea-Formaldehyde Resin Production Line | JCT Machinery

1. Formaldehyde Solution Preparation

Formaldehyde is usually added to the reactor in the form of a formaldehyde aqueous solution (usually a 37%-40% formaldehyde solution). If the formaldehyde concentration is low, it needs to be concentrated to a suitable concentration by heating or evaporation.

2. Formaldehyde Reaction

Urea and formaldehyde react under the action of an acidic catalyst at high temperature (about 80℃-100℃). The reaction process first generates a preliminary ures-formaldehyde intermediate. The reaction rate at this stage is relatively fast, and constant stirring is required to ensure uniform mixing.

3. Polycondensation Reaction

After the formaldehyde reaction, the generated urea-formaldehyde intermediate will further undergo a polycondensation reaction to form a resin with a larger molecular weight. Usually the reaction temperature needs to be raised to between 100℃-130℃ to promote the polycondensation reaction. The reaction is a process of gradually removing water. As the water is removed, the molecular weight of the viscosity of the resin also increases accordingly.

4. Resin Concentration and Water Removal

After the polycondensation reaction is completed, the reaction solution is usually concentrated to remove excess water. This step is usually achieved using an evaporator or vacuum concentration equipment. Residual moisture and impurities will be removed to ensure that the resin has appropriate viscosity and reactivity.

5. Resin Cooling and Viscosity Adjustment

After concentration and water removal, urea-formaldehyde resin will enter the cooling stage. After cooling to room temperature, the viscosity of the resin will be adjusted as needed. At this time, the viscosity and fluidity of the resin can be adjusted by adding appropriate amounts of thickeners, plasticizers and other additives.