COATING METHOD

摘要

PURPOSE:To retard temporarily solubility of a water-soluble granular material by coating the material with a coating material consisting of a polyol and a polyisocyanate while oscillating the material then forming a coating film by allowing the coating material to react and set. CONSTITUTION:A granular material consisting of a water-solution material or consisting primarily of a water-soluble material is coated with a coating material consisting essentially of a polyol and a polyisocyanate while oscillating the granular material in an oscillating mixer. A coating film for retarding the solubility of the granular material temporarily is formed on the surface of the granular material by allowing the coating material to cause reaction and setting. Another preferable method is one wherein the solubility of the surface of the granular material is retarded temporarily by allowing the coating material to cause reaction and setting, then coating the granular material with an additionally added waxy material.