| 摘要 |
PROBLEM TO BE SOLVED: To provide a mixed sand of a high mold strength or moisture tolerance and a mold manufacturing method using the mixed sand. SOLUTION: The component for making a mold comprises; a water-soluble saccharide wherein an equivalent dextrose obtained from a hydrolysis process of natural oligosaccharide and/or a starch is 10-50 against 100 weight portion of an aggregate composed of a silica sand, zirconic sand and the like, or a water-soluble saccaride, molecular weight of which is equivalent to a starch hydrolysis obtainable from a hydrolysis process of a natural high polymer saccaride, and one or more acid-hardening resins of a water-soluble phenol resin, urea resin, melamine resin and furore resin. 0.5-10 weight portion of a water-soluble coking additive, wherein a weight ratio of a water soluble saccaride: an acid hardening resin = 50:50-95:5, and a solid concentration is 20-75 weight %, and an acid, whose acid dissoriation constant Ka=1×10<-5> or more are added 1-30 weight portion against 100 weight portion of the acid hardening resin. The above mold making component is filled in a mold model and dry hardened by a dried gas such as an air or the like, or is dried by removing a water from the die by decompression.
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