SAND COATED WITH RESIN FOR CASTING AND ITS PREPARATION

摘要

PURPOSE:To prevent the decrease in curing speed and m.p. and to obtain resin coated sand for a casting having high strength by coating the molding sand with a binder prepd. by adding a specific amt. of amine hydrochloride in a phenolic resin. CONSTITUTION:There are a novolak type phenolic resin and a resol type phenolic resin as a phenolic resin. Said resins are produced by bringing various kinds of phenols such as phenol, cresol, bisphenol A or oligomer of bisphenol or similar material and a formaldehyde supply material such as formaldehyde, paraformaldehyde or similar material into reaction with each other. On the other hand, there are an aliphat. amine hydrochloride such as triethylamine hydrochloride and an arom. amine hydrochloride such as benzylamine hydrochloride. The binder prepd. by adding and mixing the amine hydrochloride at a ratio of 0.1- 10pts.wt. to and with 100pts.wt. the phenolic resin is coated on silica sand.