GB574790A - Phenol-formaldehyde resins - Google Patents

Abstract

Resins are made by heating a mixture of o-cresol with less than 50 per cent of a monohydric phenol having an alkyl or cycloalkyl substituent in the o-position and having its other two reactive positions free from substituents with 0.9-1.1 mols. of formaldehyde per mol. of phenol and a strongly alkaline catalyst. The monohydric phenol may be replaced by a mixture of such a phenol with one or more monohydric phenols having an alkyl or cycloalkyl substituent in o- and/or p-positions, all of said phenols having two free reactive positions. Modifying phenols specified are o-cyclohexyl phenol, o-tertiary butyl phenol, o-ethyl phenol, p-cresol, p-ethyl phenol, p-tertiary butyl phenol, p-tertiary amyl phenol, p-tertiary octyl phenol and p-cyclohexyl phenol. Catalysts specified are caustic soda (0.5 per cent), ammonia (2 per cent), caustic potash, calcium hydroxide and quaternary ammonium hydroxides such as trimethyl benzyl ammonium hydroxide. The resins are made by heating the ingredients under reflux till an oily resole has formed, separating and dehydrating the resole by heating in carbon dioxide to 120 DEG C., and hardening if desired by heating at 120-150 DEG C. Varnishes, paints and enamels may be made by blending the resins with drying oils, such as tung oil, together with driers such as linoleates or napthenates of cobalt or lead, and pigments. In examples, resins are made from (1) o-cresol, o-cyclohexyl phenol, formaldehyde and caustic soda; (2) o-cresol, o-cyclohexyl phenol, p-cyclohexyl phenol, formaldehyde and caustic soda. Specifications 433,539 and 573,430 are referred to.