| 摘要 |
PROBLEM TO BE SOLVED: To obtain a binder which improves the surface stability of a casting mold and suppresses the viscosity increase of a binder compsn. while maintaining high casting mold strength by using the binder compsn. contg. a water-soluble phenolic resin for carbon dioxide curing and a cyclic urea compd. SOLUTION: The water-soluble phenolic resin for carbon dioxide curing is composed of an aq. alkaline resol phenolic resin soln. an oxyanion compd. and preferably other additives for improving the casting mold strength. The preferable and more specific cyclic urea compd. is particularly preferably ethylene urea, ethylene thiourea, propylene urea, N,N'-dimethylethylene urea, N,N'- dihydroxyethylene urea, dimethylolethyene urea, acetonitrile urea and glycolyl urea, of which the ethylene urea and N,N'-dimethylethylene urea are more particularly preferable. These cyclic urea compds. may be added in the synthesis stage of the water-soluble phenolic resin for carbon dioxide curing.
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