Improvements in the process of manufacturing phenol-aldehyde resins or products thereof

Abstract

Abstract Discolourization of phenol-aldehyde resins or products containing such resins such as lacquers, varnishes, pore-fillers or moulded objects is prevented or neutralized by reacting the liquid condensation product, in the presence or absence of a solvent, first with less than 2 per cent of nitric or nitrous acid or a nitrate or nitrite and an acid or acid salt and then with an aldehyde or amine. Colouring agents are formed which marked the discolourization. In an example, phenol, with or without cresol, is condensed with formalin in the presence of potassium or sodium carbonate or hydroxide and the liquid dehydrated condensation product dissolved in ethyl alcohol is treated first with nitric or nitrous acid and then with furfurol. The solution, together with a hardening agent used at the time of use, is used as a coating.

Inventors

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