| 摘要 |
PURPOSE:To provide a titled compsn. for molds which is free from deterioration in strength in the stage of coating molds with aq. mold coating materials that cold boxes possess by consisting the same of a benzyl ether type phenolic resin incorporated and mixed with prescribed ratios of 4,4'-dihydroxy diphenyl 2,2- propane and polyisocyanate. CONSTITUTION:The above-described compsn. for cold box molds is prepd. by compounding 10-500wt% polyisocyanate with a benzyl ether type phenolic resin. As an essential requirement, 10-900pts.wt. 4,4'-dihydroxy diphenyl 2,2-propane is added and mixed with 100pts.wt. above-described resin. In this case, said propane is added by mixing the same in the stage of dissolving the resin or is added in the stage of mixing. The above-described resin is made by causing phenols (e.g.; oxybenzene) and aldehydes (e.g.; HCHO) to react under anhydrous conditions. If such compsn. is used, the generation of casting defects such as core breakage, scab, wash, etc. in the cold box mold is prevented. |
