Abstract: The invention relates to a binder (A) which contains hydroxyl groups and carboxyl groups, the latter optionally in neutralized form, wherein the binder (A) is essentially composed of a mixture of polyalkylidenepolyphenols (B) having average degrees of condensation of 2.3 to 8.0 and average molecular weights M.sub.n of 250 to 1,000, these polyalkylidenepolyphenols (B) containing phenolic OH groups and carboxyl groups, and polyaddition products (C) containing structural units (d) which are derived from epoxide compounds (D) which on average contain at least two (1,2-)epoxide groups per molecule, the structural units (d) having an average molecular weight M.sub.n of 600 to 10,000, and containing structural units (b) which are derived from the polyalkylidenephenols (B), and these polyaddition products (C) have average molecular weights M.sub.n of at least 1,100.