CURING BEHAVIOR OF WOOD ADHESIVES UNDER HIGH-PRESSURE STEAM .2.

The curing behavior of urea formaldehyde (UF) resin under steam-inject ion heating was studied using a fourier transform infrared spectromete r (FT-IR) and a solvent extraction test. In addition, hot-platen curin g and steam-injection curing of the resin were compared with each othe r. The results were as follows: (1) In the reaction of 1,3-dimethylolu rea as a model compound under steam-injection heating, the formations of linear or cyclic tertiary amide and cyclic ether were observed. The se were slightly observed in hot-platen heating. (2) In the reaction o f UF resin under steam injection heating, marked chemical changes took place, which were not observed in the hot-platen heating. Furthermore , the cyclic ether formed by the curing reaction was considered to be relatively stable even under steam-injection heating. (3) Compared wit h hot-platen heating, UF resin react more quickly and increase warm wa ter insoluble matter in steam-injection heating. Afterwards, however, it was shown that the reaction of UF resin apparently came to equilibr ium at lower temperature of 120 degrees C, and the hydrolysis proceede d at higher temperature of 160 degrees C.