METHOD FOR MANUFACTURING UREA-MODIFIED NOVOLAC PHENOL RESIN, UREA-MODIFIED NOVOLAC PHENOL RESIN OBTAINED THEREBY, AND RESIN-COATED SAND OBTAINED USING SAME

摘要

Provided are a method that can stably manufacture a urea-modified novolac phenol resin that is easy to handle and has low viscosity and a method that can effectively manufacture a novolac phenol resin modified by a large amount of urea. A resin obtained by this method and resin-coated sand that can actualize excellent casting properties using this resin are also provided. In the production of a urea-modified novolac phenol resin by cocondensing a phenolic compound, aldehydes, and urea or methylol urea, urea or methylol urea is added in small amounts continuously or intermittently to the reaction system while allowing the reaction of the phenolic compound and aldehydes to proceed, and the phenolic compound and the aldehydes are cocondensed sequentially.