PROCESS FOR THE PREPARATION OF A UREA-FORMALDEHYDE RESIN HAVING A VERY LOW MOLAR RATIO OF FORMALDEHYDE.

摘要

Process for the preparation of a urea-formaldehyde resin having a very low ratio of formaldehyde to urea, according to which urea and formaldehyde are mixed in a molar ratio of about 1: 2 and condensed between 80 and 85 degrees C at a pH of 7.0 to 7.4, the condensation being continued with lowering of the pH then modification of the molar ratio U: F, increase in pH, final adjustment of the molar ratio U: F and final adjustment of the pH. This resin is especially suitable for plywood and particle board.