RESIN COATED CASTING SAND FOR SHELL MOULD

摘要

A mixt. of ammonia resol-type phenol-HCHO resin prepd. in the presence of NH3 or hexamethylenetetramine as a catalyst, and a resol-type phenol-HCHO resin prepd. in the presence of oxide or hydroxides of metals was useful as sand coating resins for shell-mold. A mixt. contg. PhOH 940g, 37% HCHO 1150g, and 25% NH4OH 150ml was heated to 80≦̸C for 50min and was kept at the temp. for 90min to obtain a resinous material and then spraydried to obtain a solid ammonia resol-type resin.