Study On The Technology Of Wood Veneer Overlaying Wood-flour/Polyethylene Composites

As a kind of green wood-based composites,Wood plastic composites have been applied to many fields.The poor wood-like appearance of WPC limits their application in furniture and interior decoration.Decorated can not only beautify the appearance,but also can improve the performance and greatly improve its use value.If a type of excellent performance of veneer overlaying wood-plastic composites could be prepared,it would greatly increase the value of WPC and broaden its applications.But now the overlaying process study of wood plastic composites are relatively few.Veneer overlaying wood-plastic composites were prepared under the condition of hot pressing by adding the middle medium layer thermoplastic resin film,coating veneers with silane coupling agent and adding water-borne isocyanate adhesive glue agent(API).Contact angle,Fourier transform infrared(FTIR)spectroscopy,Surface bonding strength test,resistance to hot water dipping test,and scanning electron microscopy(SEM)were used to analyze the interfacial properties of the poplar veneer and the WF/HDPE composites.The feasibility of the above three kinds of WPC overlaying process were discussed.The results of the study are as follows:1)When MAPE was contained in the intermediate film,the bonding strength between the wood veneer and the WF/HDPE panel significantly improved,up to the decorative veneer of man-made board of the national standard requirements,and showing considerably higher resistance to water treatment,which can be used for wet or outdoor conditions.The flexural strength and modulus substantially improved after the WF/HDPE composites were covered with the veneer,performing almost like wood.This provides great opportunities for the application of WF/HDPE composites in building decoration and furniture.The use of an intermediate film is a feasible method to cover WF/HDPE composites with wood veneers.High performance can be achieved with no concerns regarding the emission of formaldehyde.2)The compatibility and interfacial bond strength between the modified veneer and the WPC were improved when the veneer after treated by silane coupling agent.After suitable silane coupling agent treatment,there was forming a continuous and compact layer between the veneer and WPC,which were closely linked by chemical reaction.The surface bonding strength and the resistance to water performance were significantly increased,excellent properties of coupling agent A-171 and KH-550 were screened.3)It is feasible to veneer overlaid wood plastic composites by adding aqueous polymer isocyanate adhesive(API)when the surface of WPC after mechanical polishing treatment.When the hot-pressing temperature is 80? and hot-pressing time is 15min,the interface between the different types of veneer and weak polar WPC could obtain a suitable adhesion,the surface bonding strength were above 0.4MPa,which is in accordance with "GB/T 15104-2006" requirements for decorative veneered wood-based panel.But the resistance to water is not good,which only can be used for indoor or dry conditions.4)There have differences in the surface bonding performance and water and heat resistance of the veneered WPC prepared with different process.The surface bonding strength and water resistance of the veneered WPC prepared by adding the middle medium layer thermoplastic resin film and coating veneers with silane coupling agent were better than which prepared by adding water-borne isocyanate adhesive glue agent(API).