GB806273A - Production of liquid phenolic condensation products - Google Patents

Abstract

Light-coloured, stable, water-dilutable, liquid phenolic condensation products are prepared by heating a monohydric phenol, water, 0.8-3 mols. of formaldehyde and/or a substance which acts as a source thereof for each mol. of monohydric phenol and, as a catalyst, lithium or barium oxide, hydroxide or carbonate at a pH not exceeding 9, with the free formaldehyde content of the reaction mixture is less than 5 per cent by weight, cooling the resulting reaction mixture to below 30 DEG C., adjusting the pH of the cooled reaction mixture to 6-7.2 with orthophosphoric acid or a substance which in aqueous solution acts as a source thereof, and thereafter removing separated solids from the reaction mixture. The heating is normally at 30-90 DEG C., water being removed under reduced pressure. Phenols specified include phenol, cresols, xylenols, tertiary butyl phenol, phenethyl phenol and mixtures thereof. There should be sufficient water present to dissolve the phenol(s) and catalyst. Aldehydes specified are formaldehyde, formalin, paraformaldehyde and mixtures thereof. Specified catalysts are lithium hydroxide monohydrate and barium hydroxide octahydrate. Sources of orthophosphoric acid include meta-, hypo- and pyrophosphoric acids. The precipitation proceeds more favourably when the solution contains less than 50 per cent w./w. of the condensation product; to achieve this, water or a water-miscible solvent (e.g. ethanol, isopropanol, butanols with or without small quantities of liquid monocyclic aromatic hydrocarbons such as benzene or xylenes) may be added. The reaction products are dilutable with large quantities of water and may be used as binders for glass fibres and mineral wools, such as rock wool.