Study On Fire-retardant MDF Decorated With Fire-Retardant Carbonized Birch Veneer

Birch is widespread in plantations northeast China, and it has an exquisite structure, straight texture, high fiber content and an excellent processing performance, which makes birch popular in wood-based panel and papermaking industry. Because of the disadvantages, the application of the birch is largely limited, such as its pale color, poor dimensional stability and it is perishable. After the processing of fire retardant and carbonizing, the color of the birch was darkened, the texture was prominent and the dimensional stability was improved. The color of birch after carbonizing could imitate the valuable redwood. And it could be decorated on the fire-retardant MDF as the decorating board to make the new wood-based panel product with high additional value. Not only the application of the birch was expended, but also the additional value of the product was improved. The new product obtained excellent appearance, the fire retardant property and so on. It could be used in architectural decoration, high-class furniture and interior decoration with a broad development prospect.The method of fire-retardant steep and carbonizing treatment to the birch veneer was studied, the influence of fire-retardant steep and carbonizing treatment to the color of the birch veneer was discussed based on single factor and orthogonal test, which provided the best treatment process to obtain the well-colored birch veneer; the study discussed the wettability of fire-retardant carbonized birch veneer to water and urea-formaldehyde glue. The technology of MDF decorated with fire-retardant carbonized birch veneer was confirmed by orthogonal test and mechanical performance test; the flame retardant property of MDF decorated with fire-retardant carbonized birch veneer was analyzed by CONE. The main results of the test were as follows:(1) The steep concentration, hot pressing time and hot pressing temperature had an effect on the color parameters of the veneer. The comprehensive influence order of the there factors to the color parameters L*,a*,b*Ag* and C* were hot pressing temperature, the steep concentration and hot pressing time. The best process parameters of making fire-retardant carbonized birch veneer were 195℃ hot pressing temperature,10% steep concentration and 8 minutes time of hot pressing.(2) The hydrophobicity of the fire-retardant carbonized birch veneer was heightened compared with the untreated birch veneer, thus the wettability of fire-retardant carbonized birch veneer to urea-formaldehyde glue was reduced. The wettability of birch veneer only treated by carbonizing to water and urea-formaldehyde glue was not as well as the untreated birch veneer, but better than the fire-retardant carbonized birch veneer. The higher the steep concentration was, the higher the wettability of water and urea-formaldehyde glue of veneer.(3) The hot pressing temperature, hot pressing time and the spread glue had great influences on the bonding strength, dipping peel strength and moisture content of the material in the veneering process. Glue spread had an outstanding effect on the bonding strength, and the hot pressing time affected the dipping peel strength and the moisture content maximally. The best parameters of making the MDF decorated with fire-retardant carbonized birch veneer were 110℃ hot pressing temperature,3 minutes hot pressing time and 150g/m2 glue spread based on the mechanical properties and the production cost.(4) The flame retardant property of MDF decorated with fire-retardant carbonized birch veneer compared with the MDF decorated with the untreated birch veneer was analyzed by CONE. The experiment results showed that MDF decorated with fire-retardant carbonized birch veneer had an outstanding flame retardance, smoke suppression and less toxic gases, it could be used as the interior construction materials and the decoration material with safety performance.