PURPOSE: The titled composition capable of improving bulking properties and corrosion resistance of an epoxy resin, forming a coating film having improved transparency, corrosion resistance, etc., obtained by blending a high molecular weight epoxy resin with a coumarone resin modified by formaldehyde.

CONSTITUTION: 100pts.wt. epoxy resin is blended with 5W400pts.wt. modified coumarone resin obtained by polymerizing 100pts.wt. raw material oil (fraction at 110W230°C) for producing coumarone resin form a gas oil of coke oven of coal or tar gas oil with 5W80pts.wt. formaldehyde as a modifying agent in the presence of a catalyst (e.g., sulfuric acid, etc.). The high molecular weight epoxy resin has a molecular weight not less than 900.

EFFECT: A laminate or a cast material having more improved transparency and a coating film capable of forming a cured material having more improved corrosion resistance and weather resistance than those of a conventional material blended with coumarone resin are obtained.