Method of preparation of a resinant solution of fenol-resorcinol-formaldehido fusible and soluble. (Machine-translation by Google Translate, not legally binding)

摘要

Method for the preparation of a soluble and fusible phenol-resorcinol-formaldehyde resinous solution, characterized by an infinite dilution capacity, whose resin comprises 50 to 95 moles of phenol with 5 to 50 moles of resorcinol per 100 moles of total phenol and resorcinol, and from 0.55 to 0.75 moles of formaldehyde per mole of total phenol and resorcinol, which method is characterized by the steps of (a) reacting said phenol with said formaldehyde at an initial pH of 8.5 to 9, 0 and in the presence of an alkali metal sulfite catalyst in a proportion of 0.04 to 0.09 mol per mol of formaldehyde; (b) heating the reaction mixture to reflux until it has a viscosity of 4.7 to 8.8 poises; and (c) adding said resorcinol and continuing the reflux until the resin has a constant viscosity of 27.0 to 46.3 poises. (Machine-translation by Google Translate, not legally binding)