A water-soluble reactive binder, characterized by a combination of at least three of the components(a) at least one halogen-free polycarboxylic acid compound;(b) at least one salt-forming substance selected from the group consisting of alkali metal, alkaline earth metal and quaternary ammonium salts, organic bases and ammonia;(c) at least one component selected from the group consisting of(c1) a polymer containing OH groups; and(c2) an epoxide compound,wherein the components (a) to (c2) are present as such or at least partially in chemically bonded form, a process for its preparation, an article coated with said binder and an adhesive containing said binder.