Process for the preparation of rapidly hardening castable phenol-formaldehyde resins and tension-free castings produced therefrom

摘要

Rapidly hardening castable resins are prepared by adding maleic anhydride alone or mixed with a polyvalent alcohol to an unmodified phenol-formaldehyde resin which has been precondensed in alkaline medium and then acidified. In examples: (1) phenol, formalin, ethanol and sodium hydroxide are heated, monochloroacetic acid and lactic acid added and water distilled off. Maleic anhydride is then added and the mixture moulded; (2) the resin of example (1) is completely dehydrated, a preheated mixture of glycerol and maleic anhydride added and the mixture moulded.