| 摘要 |
An improved process for substantially increasing the shelf-life of aqueous solutions of melamine-formaldehyde resins wherein the molar ratio of melamine to formaldehyde is from 1:1.7 to 1:3.5 by the addition of a stabilizing amount of urea after condensation, which process includes the steps of adjusting pH of the resin solution before and after the dissolution of the urea within certain narrow but easily controllable pH ranges. The properties of the resin solution can be further improved and the stabilizing effect of the addition of urea increased by adding a monohydric C1-C4 alkanol during condensation of the resin. |
