PURPOSE: To produce a mold which is superior in dimensional accuracy, does not produce any defect such as cracking and permits the use of regenerated sand as well, by using the specific novolak type phenolic resin as a binder at the time of producing bindercoated sand for shell molds.
CONSTITUTION: In producing a mold used in a shell mold method, the surfaces of sand for mold are coated with a binder. As the binder, a novolak type phenolic resin mixed with 5W20% hexamine is added at 0.5W5pts. based on 100pts. snad. The novolak type phenolic resin is the modified novolak type phenolic resin modified by bisphenols and cumarone compounds, and the one of 1,500W3,000 in the weight average mol.wt. is used. Calcium stearate, waxes, salicylic acids, clay, iron oxide or urea may be used as binding assistants. Cracking of the mold owing to thermal expansion at the casting of molten metal does not occur, and the use of regenerated sand is possible as well.
SATOU TADASHI
YOSHIMI SHIGEMITSU
MIZUNO KUNIAKI
AISHIN KAKO KK