| 摘要 |
PURPOSE:To provide a compsn. for molding a casting mold which suppresses the urethanation reaction of film sand prior to molding and eliminates the deterioration in the quality of the sand by allowing a material which generates HCl by hydrolysis to exist in the compsn. for molding of the casting mold which uses a phenolic resin and polyisocyanate in the presence of a gaseous amine catalyst. CONSTITUTION:A compsn. compounded with 18-pts.wt. polyisocyanate (e.g.; diphenyl methane diisocyanate) and 25-125pts.wt. amine in 100pts.wt. solid of a phenolic resin (e.g.; benzyl ether type phenolic resin) is prepd. The above-described phenolic resin is used preferably by dissolving said resin uniformly in an org. solvent such as alcohol or the like and controlling the viscosity to <=10 pound/25 deg.C. It is necessary to allow 0.1-7pts.wt. material which is expressed by the formula and generates HCl when hydrolyzed (e.g., a silane compd.) based on 100pts.wt. polyisocyanate to exist in this compsn. As a result, the material existing in the compsn. is hydrolyzed by the water contained in silica sand to generate HCl during kneading with sand, and the urethanation reaction of the coating sand prior to molding is suppressed. |
