Process for the preparation of dodecamethylenebismelamine and the use thereof

A process for the stabilization of aqueous formaldehyde solutions, comprising introducing a sufficient amount of dodecamethylenebismelamine into an aqueous formaldehyde solution wherein the bismelamine is a 15 to 25 weight percent solution, based on the total amount, and methoxymethanol (methyl hemiformal) is used as solvent in form of a methanolic solution with a methoxymethanol content of 70-85%, said dodecamethylenebismelamine having been prepared by a process comprising reacting 2,4-diamino-6-chloro-1,3,5-triazine with 1,12-diaminododecane as reactants in an alkaline, aqueous suspension, said 1,12-diaminododecane having been dissolved in a water-miscible, organic solvent and then added to said suspension, carrying out the reaction at reflux temperature, cooling the formed reaction mixture to room temperature and separating the resulting crystallized dodecamethylenebismelamine product.