| 摘要 |
<p>A process for the preparation of a tack free urea/formaldehyde resin having a solids content of 64-66% and a viscosity at 25.degree.C of 150-300 cps, in which a formaldehyde source is treated with a strong organic base, urea is added to obtain a formaldehyde/urea mole ratio lying between 1.90 and 2.35 : 1, the pH is adjusted to 5.0 - 6.3 with an acid, the polymerization reaction is stopped when the product has reached the required vicosity by an inorganic base and a further amount of urea is added such that the final formaldehyde/urea mole ratio becomes 1.38 to 1.70.</p> |
