| 摘要 |
<p>1. A process for the production of co-condensates of phenol and melamine with formaldehyde in aqueous solution, wherein a) formaldehyde and phenol are condensed in a molar ratio of 4:1 to 10:1 in a conventional manner in aqueous solution at an initial pH of at least 7.5 until the condensate just exhibits unlimited dilutability with water (or limited dilutability with 5 % strength magnesium sulfate solution), and b) the aqueous condensate thus obtained is condensed with at least 0.3 mole of melamine per mole of formaldehyde at a pH of 7.5 to 10 until it exhibits limited dilutability with water, with the proviso that the amount of formaldehyde, based on the sum of the molar amounts of melamine and phenol, is at least 1.5.</p> |
