Melamine Modified Low Molar Ratio Urea-formaldehyde Resin Adhesive Of Medium Density Fiberboard (MDF)

Urea-formaldehyde resin adhesive is widely used in wood-based panels of synthetic resins, urea-formaldehyde resin reaction principle determines its inherent disadvantages:free formaldehyde to produce the pollution of the environment; water resistance and resistance to aging and poor. Also face a variety of problems, such as medium density fiberboard (MDF) plate production quality varies greatly, which is mainly based on the contradiction between the formaldehyde emission and mechanical properties of the rapid development of wood-based panels. To solve this problem, this paper, melamine modified the ultra low molar ratio urea-formaldehyde resin, the development of low formaldehyde emission, excellent mechanical properties of medium density fiberboard with urea-formaldehyde resin adhesive.First, using the molar ratio to0.96:1reduce the synthesis of urea-formaldehyde resin, melamine was added during the synthesis, the primary modifier and join other modifiers such as polyvinyl alcohol, ammonia, and changing the the melamine added amount and the adding method, explore this colors of the impact of change on the physical properties of the synthetic resin, synthetic resins in the process of free formaldehyde content below0.1%; then with a synthetic resin, and select the appropriate hot-pressing process curve pressing density fiberboard, research melamine added amount and add change in the way the bond strength, formaldehyde emission medium density fiberboard, bending strength and elastic modulus,24-Hour Thickness Swelling variation. The increase of the amount within the knot with melamine strength tended to increase, formaldehyde emission, thickness swelling overall declining trend. Change the a melamine feeding mode, when the melamine pre-feeding accounts for2%of the amount of urea bond strength modified sheet effect; formaldehyde emission in early feeding amount of1%, significantly lower; feeding amount of the period more than3%when the plate thickness swelling too large. Melamine feeding amount too much the plate performance improvement is not obvious, pressed sheet performance can achieve the requirements of GB/T11718-2009.Finally, through the comparison of the experimental analysis, the suppression of medium density fiberboard best urea-formaldehyde resin adhesive formulations and hot technology curve. Derived by further experiments with low formaldehyde emission plate excellent mechanical properties of the experimental program. The conclusion that when the melamine Add accounted for6%of the amount of urea, before the feeding amount of1%using the same hot-pressing process to suppress the MDF formaldehyde emission3.7mg/100g (perforated extraction) level E0national standards, internal bond strength is0.54MPa. A good balance between the above contradictions. Control formaldehyde emission for the actual production cost savings, improve the mechanical properties of the sheet and low toxicity and environmental protection to provide a theoretical basis.