Property of nano-SiO2/urea formaldehyde resin

In this paper, we discuss the effects of a nanometer silicon dioxide (nano-SiO₂) coupling agent, dispersal methods and the amount of nano-SiO₂/urea formaldehyde resin. The results of our study indicate that when nano-SiO₂, using KH-550 silane as a coupling agent, was added to UF resin by discontinuous ultrasonic vibration, its properties improved effectively. When the content of nano-SiO₂ was below 1.5%, the amount of free formaldehyde decreased, and the viscosity and bonding strength of resin increased with an increase in the added nano-SiO₂, which did not prolong the curing time. The performance indices of plywood, particleboard and medium density fiberboard (MDF), hot-pressed by nano-SiO2 (1%)/UF resin (F/U molar ratio=1.2), exceeded the requirements of the National Standard. Their free formaldehyde emission reached E1 grade. Finally, we analyzed the mechanism of the strengthening effects of nano-SiO₂ on UF resin by means of infrared spectrum analysis and X-ray photoelectronic spectrum (XPS). __________ Translated from Scientia Silvae Sinicae, 2005, 41(2) 译自: 林业科学, 2005, 41(2)]