PURPOSE: The titled composition that contains a low-molecular modified diene polymer resulting from addition of maleic anhydride or its derivative to a specific low-molecular diene polymer and a crosslinking agent, thus forming coating films with high impact strength, heat resistance and adhesion to protect the metallic surface or the like from corrosion.

CONSTITUTION: For example, maleic anhydride or its derivative is added to a low-molecular diene polymer of 5,000W200,000 molecular weight (as the viscosity average molecular weight) and more than 75% 1,4-bond content at a molar ratio of 13W30 to 100 recurring units of the diene polymer to prepare a low-molecular moldified diene polymer. (A) 100pts.wt. of the resultant diene polymer are mixed with (B) 0.1W25pts. of a crosslinking agent, when necessary, (C) a solvent such as toluene to give the objective composition.

USE: It is used to protect the surface of slates, plastics or concrete.