| 摘要 |
PURPOSE:To provide a resin compsn. for a self-curing mold which is improved in the collapsing property after casting by using a resin prepd. by dissolving phosphate or the like in urea and a furan phenolic resin modified with polyhydric phenols. CONSTITUTION:0.1-1.5mol polyhydric phenols, 1.1-7.5mol formaldehydes, and 0.2-20mol furfuryl alcohol are used with 1.0mol phenol, and these are caused to react in the presence of an alkali catalyst and are then dehydrated. 1-10pts.wt. urea (deriv.) is added to 100pts.wt. product of reaction obtd. by such a method to obtain a furan-modified phenolic resin. 10-50pts.wt. >=1 kinds among phosphate, phosphite, phosphonate, etc. are compounded with 100pts.wt. modified phenolic resin, whereby the resin compsn. for a self-curing mold is obtd. Such resin compsn. is easily collapsed by mechanical impact alone even without heat treatment after casting. |
