STAINPROOFING AGENT FOR COLD BOX PROCESS

摘要

PURPOSE:To provide a stainproofing agent containing a specified phosphonic acid or salt thereof as essential ingredient and preventing staining when used together with a known release agent. CONSTITUTION:The stainproofing agent for cold box process contains phosphonic acid of the formula [where Rf is perfluoroalkenyl; Ar is (substituted) aromatic group; l is 1-3; n is 1 or 2; M and M' are residues of a salt (e.g. Mg, Zn or triethanolamine)] or salt thereof as essential ingredient. For example, conventional release agents such as those based on silicon, wax or resin tend to cause staining of molding sand due to blowing when used in a cold box process. The stainproofing agent prevents staining when used in combination with these release agents. Among the phosphonic acid and salt thereof, partly neutralized salt gives best results.