The Modification Of Poplar Plywood With Multi-functional Wood Protective Agent

Plywood is the leading product of man-made board in our country,because of its high strength,small volume weight ratio and simple processing.Plywood can maintain some advantages of natural wood such as decorative pattern,and is widely used in furniture,building and interior decoration.However,untreated plywood belongs to combustible materials which with fire hazards,as well as it will be damaged by decay fungi and mold.Therefore,the plywood treated with appropriate protective agent to improve the added value and service life has great significance.In this paper,Various protective agents were prepared with more than 10 kinds of agents such as dicyandiamide,phosphoric acid and its derivatives,borides,guanidine compounds and so on.The results were as follows:?1?Protective agent A:Composed of Mn CL₂,H₃PO₄,H₃BO₃and NH₄Cl.The protective agent has a positive effect on the flame retardant performance of plywood.The total heat release?THR?was 90.04%lower and the total smoke release?TSR?was 68.40%lower than the control group.The formaldehyde release of plywood was 14.82%lower than control.Decay resistance reached grade?level.Protective agent A had no effect against mold AV and certain control effect against to mold TV.Although the mechanical strength was seriously reduced,the treated plywood can still meet the standard requirements of GB/T 9846-2015.?2?Protective agents B and C:which were composed of C₂H₁₀N₆·H₃PO₄,Na₂B₈O₁₃·4H₂O,CN₄H₈SO₃and C₂₁H₃₈NCl in different ratios.These protective agent had good flame retardance,decreased the THR by 82.88-86.19%,and decreased the TSR by 65.73-85.95%.Protective agent B and C had certain effect of formaldehyde capture effect,reduced the formaldehyde release of plywood.Decay resistance reached grade?level.The mildew proof test showed that the protective agent C had a good resistance to AV and TV,and the prevention effect on TV was 100%.The protective agent B had no effect on AV,but its prevention effect on TV was 75%.?3?Protective agent D:which were composed with dicyandiamide?C₂H₄N₄?,phosphoric acid?H₃PO₄?,magnesium sulfate?Mg SO₄?,urea?CH₄N₂O?,boric acid?H₃BO₃?,borax?Na₂B₄O₇·10H₂O?.Compared with the control group,THR and TSR of treated plywood decreased by 91.94%and 76.81%respectively.Decay resistance of treated plywood reached grade?level,and had good resistance on the two kinds of mold with the prevention effect both were 75.00%.Protective agent D had a small negative effect on the mechanical properties of the plywood and had a strong ability to capture formaldehyde.The formaldehyde emission decreased 82.31%compared with the control group.?4?Protective agents E,F,G:which were composed of different ratio of diammonium phosphate??NH₄?₂HPO₄?,ammonium dihydrogen phosphate?NH₄H₂PO₄?,boric acid?H₃BO₃?,borax?Na₂B₄O₇·10H₂O?,tetrachloric acid disodium(Na₂B₈O₁₃·4H₂O).A three protective agents had good flame retardant effect.Their HRR,THR and EHC all reduced to a large extent and F has the best effect.Protective agents E,F,G all had a small negative impact on the mechanical properties of plywood,and F had the least impact effect.At the same time,the formaldehyde emission of plywood treated with E,F and G decreased significantly compared with that of control group K.Decay resistance of treated plywood reached grade?level,and had good mould proof effect.?5?Based on the comprehensive analysis of the indexes of all protective agent treated plywood,it was concluded that groups D,F and E had the best comprehensive performance,and group A has the lowest ranking.Although D,F and E had similar comprehensive effects,but group E had the best decay and mildew resistance.Protective agent F had the least impact on the mechanical properties of plywood and the best fire resistance.The cost relationship of each formula was:A>C>B>E>D>F>G.