Preparation method of urea-formaldehyde resin with low free formaldehyde content: by reducing the molar ratio of formaldehyde to urea and adopting the method of feeding urea for three times, the production process is simplified, the free formaldehyde content in urea-formaldehyde resin is reduced and its performance index is improved. Using polyvinyl alcohol and melamine as modifiers, the water resistance and initial adhesion of adhesive solution were obviously improved. The ratio of raw materials, reaction time and temperature, and pH value of medium will all affect the performance of the product.
See the literature: Dongxue, Development of Urea-formaldehyde Resin with Low Free Formaldehyde Content, fine and specialty chemicals, 2003,11(13): 21-22.