| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a mold with which the mold can stably manufactured for a short time without needing to heat the mold to a so high temp., without needing to use a harmful chemical material and moreover, without generating a harmful gas. SOLUTION: Resion coated sand 2 prepared by mixing an isocyanate compound binder with a refractory aggregate, is filled up into a mold 1. Then, steam is injected into the mold 1 to harden the isocyanate compound binder. Thus, the whole resin coated sand 2 in the mold is instantly heated with steam and the isocyanate compound binder can be hardened. As a hardening agent for this isocyanate compound binder, a compound containing active hydrogen easily reacted with the isocyanate group, e.g. water, polyol, an amine compound, a carboxyl compound or the like is blended and as a hardening catalyst, amines, organic metallic salt or the like is blended to make the resin coated sand have self-hardening property of a heat-hardening type and to be used.
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