Abstract:

The effects of nano-SiO₂ coupling agent, dispersing methods and its content on the properties of the urea formaldehyde (UF) resin were discussed. The test results indicated that when nano-SiO₂, incorporated with KH-550 silane coupling agent, and was put into UF resin by discontinuous ultrasonic vibration, it had the best results. When the content of nano-SiO₂ was below 1.5%,the content of free formaldehyde decreased,viscosity and bonding strength of resin increased with the nano-SiO₂ added,which would not affect the curing time. The performance index of plywood, particleboard and medium density fiberboard(MDF) , pressed by nano-SiO₂(1%)/ UF resin (F/U mole ratio=1.2), were above the demand of national standard and their dissociate formaldehyde release reached E₁ grade. Furthermore, strengthening mechanism for the effects of nano-SiO₂ on UF resin were analyzed by means of infrared (IR) spectrum analysis and X-ray photoelectronic spectrum (XPS).

Key words: nano-SiO₂, UF resin, bonding strength, free formaldehyde, XPS