Process for the preparation of phenol-urea-formaldehyde resins

摘要

The invention relates to a process for the preparation of phenol-urea-formaldehyde resins by polycondensation, in which phenols or mixtures thereof are subjected to complexing with urea in the mass or in solution, and the resultant solid complexes, which contain 1 mol of urea and 2 moles of phenols, are then separated by crystallisation and subjected to polycondensation with formaldehyde in alkaline, aqueous solution at temperatures of up to 110@C.