[ Formula ]
Molar ratio of urea to formaldehyde 1 : ( 1.05~1.2 )
Polyvinyl alcohol ( % ) 0.4~1.0
Modified starch ( % ) 1.0~2.0
20% amount of acetic acid
25% amount of ammonia
20% aqueous sodium hydroxide solution
   The above materials are all industrial products.
   [ Preparation method ] In the enamel reactor, first add 37% formaldehyde solution, start stirring, adjust the pH to 8.1 with 20% acetic acid, 25% ammonia, add the first batch of urea and polyvinyl alcohol, quickly Warm up to 85~90 °C , keep at this temperature for 1 hour, then intermittently measure the viscosity and turbidity point. After the two arrive, use 20% sodium hydroxide solution to adjust the pH to 7.5~8.0 and add the second batch of urea at 85 °C . After a half-hour reaction at ~90 °C , the turbidity point was measured intermittently. After reaching it, the pH was adjusted to 8.0 with 20% sodium hydroxide solution. The third batch of urea and the modified starch were fed to room temperature for discharge.