| 摘要 |
PURPOSE:To obtain a binder compsn. which maintains the initial strength and pot life strength of a casting mold at a high level by using a phenolic resin having a specific mol. wt. and methylol group content and polyisocyanate liquid as a binder and further using a basic material as a catalyst. CONSTITUTION:Formation of the casting mold is executed by using the binder compsn. contg. the phenolic resin and polyisocyanate liquid as the binder and the basic material as the catalyst. The above-mentioned phenolic resin is preferably of a benzilic type and the resin having 240-480 number average mol. wt. of the solid component thereof and 15-29wt.% methylol group content is used. The adequate using ratio of the polyisocyanate liquid is about 50-200 parts. wt. per 100 pts. wt. phenolic resin. The casting mold formed by the molding sand using the above-mentioned binder compsn. for molding maintains the initial strength and pot life strength at a high level.
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