RESIN COMPOSITION FOR BINDING MOLDING SAND

摘要

PURPOSE:To prevent casting defects by mixing specific weight % of a specific orthocresol novolak type opoxy resin, etc. with a polyvalent glycidyl compd. having an isocyanuric ring then compounding specific % of dicyandiamide. CONSTITUTION:A low melt viscosity is required in a temp. range of 100-150 deg.C in the manufacture of resin-coated sand. A mixture composed of 5-40% orthocresol novolak or phenol novolak type epoxy resin having >=60 deg.C softening point and <=2,000 number average mol.wt. and the balance a glycidyl compd. having an isocyanuric ring is prepd. Dicyandiamide is compounded at 5-40% as a curing agent with 100pts.wt. resin mixture. The resin composition is added at 1- 10% to the molding sand by which the warm strength is increased, the collapsing property after casting is improved and casting defects are prevented.