| 摘要 |
PURPOSE:To prevent a shell mold from cracking by preparing a raw material consisting essentially of phenols and a by-product obtained in refining bisphenol A, in specific weight percentage, and including further a silane coupling agent and an amide of prescribed molecular weight, etc. in the material. CONSTITUTION:A raw-material phenol consists essentially of phenols of phenol or cresol, etc., a chroman compound produced as a by-product in refining bisphenol A, and a by-product containing bisphenol, etc. Further, the ratio of component between the phenols and the by-product of bisphenol A is regulated, in weight ratio, within a range of 30/70-95/5, and a silane coupling agent, an amide such as an acrylamide of <500mol.wt. and a lubricant added in <=5wt% to a phenol resin, are also included in the material. By such a method, the strength of a shell mold is improved and the generation of a crack is prevented. |
