Synthesis Process Development of Diethylene Tricarbamide as a Starting Material for Wood Composite Binder Diethylene Tricarbamide–Formaldehyde Resins

Abstract

Abstract A three-step carbamylation reaction of diethylene triamine (DA) with urea was investigated to find an efficient synthesis procedure for large-scale production of diethylene tricarbamide (D), a monomer of D-formaldehyde resin binders for wood composite boards with very low formaldehyde emission potential. n-Butanol, pyridine, and others with minor amounts of polar solvents were investigated as a reaction medium. Urea is added to the solvent in a stirred reactor and heated to the boiling point of the solvent, which is about 110°C to 130°C. This was followed by the gradual addition of DA while allowing evolved ammonia to escape through the condenser. A delicate balance exists between voluminous particles of di-substituted intermediates and the hard fine particles of tri-substituted final product, and an excessive buildup of the former often occurs, resulting in stirring difficulties, reaction stoppage, and low reaction yields, which are minimized by adding some polar solvents and also by programmed addition of DA. Free-flowing microcrystalline particles of D were obtained in yields of 90 to 98 percent based on DA in 6 to 12 hours of reaction by simple filtration, hot washing with solvents, and drying procedures. These organic solvent–based synthesis procedures appear possible to adapt to large-scale production of D. The ammonia that evolves from the reaction needs to be captured, and solvent losses should be minimized. The high current price of DA, the need to reuse ammonia, and the complexity of the reaction indicate that a company that manufactures ammonia, urea, and DA fit to adopt this technology in support of the wood composite board industry.