| In this paper, three different kinds of processes have been tried. Determine the optimum technological conditions of fire-retardant medium density fiberboard and plywood through orthogonal test. Discuss the effects of different factors and levels of each process on flammability and physical and mechanical properties. Conclusions can be divided into three parts.First, using HTSi-01 Nano-SiO2 appropriately can enhance the internal bond strength, MOR and MOE, but slightly lower the flammability. According to the effect on internal bond strength in order, the optimum technological conditions are as follows:the amount of urea-formaldehyde resin (10 wt.%)> the amount of Nano-SiO2 (4 wt.%)> hot pressing temperature (160±5℃)> the amount of flame retardant (13 wt.%).Second, adding 4A zeolite appropriately can enhance the bonding strength of flame-retardant plywood, and 8% is best. When the addition level of zeolite is 0～8%, the oxygen index will slightly decline, with little effect. When the addition level is over 8%, the oxygen index will significantly decline. In this experiment, the optimum technological conditions are as follows:the addition level of zeolite (8 wt.%), the concentration of flame retardant (15 wt.%), glue spread (380g/m2), and hot pressing temperature (120℃).Third, in the synthetic process of modified P-N flame retardants, it is best to add 2% Nano-SiO2 and catalyst together into reaction kettle before polymerization. Bonding strength will decrease when increasing concentration of flame retardant. Only with proper hot pressing temperature can urea-formaldehyde glue fully cure. Flammability is better with longer impregnation time and higher concentration of flame retardant. Rising hot pressing temperature brings worse flammability. According to the effect on bonding strength in order, the optimum technological conditions are as follows:the concentration of flame retardant (10 wt.%)> hot pressing temperature (120℃)> impregnation time (3h)> glue spread (280g/m2). |
PDF Full Text Request