| 摘要 |
Urea-formaldehyde precursors are produced in a two-stage process. In the first stage, urea is slowly added to an acidic solution of formaldehyde at a pH of 1.0 or less, at a rate that maintains the temperature at 50 DEG C. but not in excess of 98 DEG C. When an F/U mole ratio of 3.25:1 to 2.5:1 has been attained, the pH is adjusted to the basic side, generally from about 7.2 to about 8.0. In the second stage, additional urea is added to the condensate produced in the first stage, to attain an F/U mole ratio of 3.0:1 to 2.5:1. The condensate and precursor have fertilizer applications. The precursor is useful in urea-formaldehyde resin production.
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