Abstract: This paper has reported a new method of reaction between urea and formaldehyde under low temperature and low pH value. Investigations show the different reaction mechanism between urea and formaldehyde. The process of reaction involves a relatively short cycle time. The chemical structure and skeleton of the resin are basically changed. It contains much more methylene functionality than methylene other functionality in the cured resin. The resin exhibits hydrolytic stability and the formaldehyde emission is greatly reduced. Authors suggest that the reaction resultant of urea and formaldehyde under low temperature and low pH value can be considered as a prepolymer (basic resin) to solve the difficult issues, in which the storage life of urea resin adhesive is not long and gelling systems are usually obtained since the ambient temperature variation in storage and shipping.

Key words: Urea resin, Wood adhesive, Particleboard performance, Molecuiar weight distribution