PURPOSE: To prepare an epoxy resin composition having improved low-temperature curability, acid resistance and water resistance, and giving the coatings having improved adherence and wet-on-wet coating processability, by adding a hydroxyl group-containing aromatic resin and an isocyanate hardener to a hydroxyl group- containing epoxy resin.

CONSTITUTION: A new epoxy resin composition comprising (A) a hydroxyl group- containing aromatic resin having a hydroxyl value of 25 - 150 (e.g. copolymer of styrene with phenol), (B) a polyol comprsing an epoxy resin having two or more hydroxyl groups, or its derivative and (C) an isocyanate hardener (e.g. 2,4-tolylene diisocyanate). The preferable compounding ratio of (A) - (C) is 60 - 5 wt.%, 40 - 95 wt.% and 0.3 - 1.5 equivalent of isocyanate group (on the bais of 1 equivalent of hydroxyl group), respectively.

EFFECT: The excellent characteristics of epoxy resins, particularly of chemical resistance and oil resistance, are not lowered.