Studies On Manufacture Techniques And Properties Of Preserved Plywood

Because plywood that was made of timbers was susceptible to insect and rot,plywood were treated with preservative to achieve anticorrosive, insect resistant andantimildew function and to prolong the utilization time limited. But plywood treatedwith preservative would reduce the adhesive wettability, some ingredients of thepreservative may be interact with adhesive, lead to the decrease of bonding strength,and reduce the performance of the final product. Therefore, manufacturer was inurgent to get manufacture techniques of preserved plywood. This paper studiedcomprehensively the manufacturing techniques of preserved masson pine and poplarplywood to reveal the good applicability and feasibility of the manufacturingtechniques for preserved plywood.The purpose of this study was to optimize the techniques of preserved plywood whichwere prepared with preservatives (ammoniacal copper quaternary (ACQ)、borates incooperation with additvs) and bonded with urea-formaldehyde(UF) resin or phenolicformaldehyde (PF) resin, using one-factorat-at-a-time method and Response SurfaceMethodology. It was analyzed the effect of preservatives on adhesion properties ofpreserved plywood by differential scanning calorimetry (DSC) and JC2000A dynamiccontact angle fiber tension-meter; the plywood samples were then characterized byFourier Transform Infrared Spectroscopy (FTIR). The decay resistances amongplywood samples with optimum techniques were also studied. The results of thisstudy are summarized as below:1) Research on the manufacturing techniques of ACQ preserved plywood bondedwith PF resin, ACQ preserved plywood bonded with UF resin and boric acidpreserved poplar plywood bonded with UF resin using one-factorat-at-a-time methodshowed that the optimum manufacturing techniques of ACQ preserved plywoodbonded with PF resin were as follow:2（wt%）of ACQ, dipping time of the veneersfor1.5hours, drying conditions of the masson pine veneer at80℃,6hours, dryingconditions of the poplar veneer at60℃,8hours. The average absorption dose,bonding strength and leaching rate of preserved plywood using optimum manufacturing techniques were7.80kg/m~3and9.10kg/m~3,1.42MPa and1.54MPa,0.7%and0.5%, respectively.The optimum manufacturing techniques of ACQ preserved plywood bonded with UFresin are as follow:1(wt.%) of ACQ, dipping time of the masson pine veneers for2hours, dry conditions at30℃,12hours; dipping time of the poplar veneers for1.5hours, dry conditions at60℃,4hours. The average absorption dose and bondingstrength of preserved plywood using optimum manufacturing techniques were4.21kg/m~3and4.53kg/m~3,1.15MPa and1.28MPa, respectively.The optimum manufacturing techniques of boric acid preserved poplar plywoodbonded with UF resin are as follow:2(wt.%) boric acid, dipping time of the veneers1.5hours, dry conditions at70℃,4hours. The average absorption dose and bondingstrength of preserved plywood using optimum manufacturing techniques were4.96kg/m~3and1.33MPa, respectively.2) Research on the manufacturing techniques of glyoxal/glycerol in cooperationwith boric acid preserved massion pine plywood bonded with PF resin, glyoxal/glycerol in cooperation with borax preserved poplar plywood bonded PF resin andglycerol in cooperation with boric acid preserved massion pine plywood bondedwith UF using Response Surface Methodology showed that the optimum operationparameters of glyoxal/glycerol in cooperation with boric acid preserved massionpine plywood bonded with PF were as follow:2.00(wt.%) of glyoxal inpreservatives, drying temperature at70℃, and drying time for5hours. The averagebonding strength and retention rate of massion pine preserved plywood usingoptimum manufacturing techniques were1.42MPa and45.52%, respectively.The optimum operation parameters of glyoxal/glycerol in cooperation with boraxpreserved poplar plywood bonded with PF were as follow: weight content of glyoxalin preservatives at3.00%, drying temperature at70℃, and drying time for5hours.The average bonding strength and retention rate of poplar preserved plywood usingoptimum manufacturing techniques were1.46MPa and49.38%, respectively.The optimum operation parameters of glycerol in cooperation with boric acidpreserved massion pine plywood bonded with UF were as follow: glycerol at1.91 (wt.%), drying temperature at75°C, and drying time for4hours. The Bondingstrength of preserved masson pine plywood using the optimum technique was1.38MPa.3) The results of FTIR spectra were showed as follow: The places fixation of ACQ inplywood was mainly cellulose and hemicellulose, and a small amount of lignin; Thefixation of ACQ was slowly at low temperature in plywood, thus hindering thechemical reactions between ACQ and extractives and decreasing the effects of ACQon masson pine plywood bonded by UF resin; The glyoxal/glycerol and borax orboric acid compound was reacted with wood, thus decreasing the effect of borate onPF curing and the effects of preservatives compound on the preserved plywoodbondes by PF resin, while the retention percentage of boron in plywood wasincreased; The effect on bonding strength of the preserved masson pine plywood wasnot negative because the borate ester was obtained by the reaction of boric acid andglycerol, and the negative effect of borate ester on wood structure and bondingstrength was little; the structure of poplar wood did not change due to boric acid wasnot reacted with poplar wood, which was one of the reasons the decrease for theeffect boric acid on bonding strength of UF preserved poplar plywood.4) Contact angle and DSC showed that the effect of masson pine and poplar veneerby elected preservative treated on adhesive curing was little.5) The weigh loss rate of the decay resistances among plywood samples withoptimum techniques were less than10%, which has already reached strong decayresistant.