Using the production method and phenolic resins, and it urea-modified novolac type obtained by it of the urea-modified novolac-type phenolic resin resin-coated sand obtained Te

摘要

easy handling, the urea-modified novolac-type phenolic resin having a low viscosity, stable manner and a manufacturing method that can be, and modified phenolic novolak resin with a large amount of urea, it is provided advantageously techniques can be produced. Also, whereby the resulting resin, and further, by using the resin, there is provided a resin-coated sand which can brought excellent mold properties. A phenolic compound, and an aldehyde, the allowed co-condensation and urea or methylol urea, when preparing the urea-modified novolac-type phenolic resins, while allowed to proceed the reaction of the phenolic compound and an aldehyde, urea or methylol urea , that the reaction system is continuously or intermittently added in portions and so as to engage successively co-condensation with such phenolic compounds and aldehydes.