| Abstract [eng] |
When gluing sawn wood sheets with the polychloroprene glue KLEIBERIT C114/5 in a furniture manufacturing enterprise, the following sheet bonding defect are observed: bloating between the early and late wood layers and delaminations. Therefore, it is necessary to examine the factors which cause such defects. The causes of emergence of defects after the gluing process were examined by performing such primary tests as determination of the humidity and the wettability angle of the wood, open glue retention time and effect of the type of wood on the bonding strength of the PChP glue. The bonding strength of the PChP glue was also compared with the bonding strength of the PVAc glue. This resulted in the determination of the bonding strength of the PChP glue and examination of the influence of the wood surface roughness on the bonding strength of the PChP glue. The tests were chosen for the purposes of establishing the reasons of emergence of defects when gluing maple wood with the PChP glue. It was established that the bonding strength of the PChP glue is influenced by the open retention time of the glue, the bonding pressure and the structure of the bonding material. According to the recommendations, the gluing of the sawn wood sheet and HPL should be performed under the bonding pressure of at least 0.5 Mpa. The properties of the surface of the bonded materials are one of the main indicators, which determine the bonding strength and the reasons of emergence of defects after bonding. After the sanding of the maple wood surface with a P60-type abrasive paper, the surface roughness increased by 37 %, and after the sanding with a P80-type abrasive paper – by 45 %, when compared with the control maple wood samples. Although the bonding strength decreased respectively by 9 and 6 %, the fragmentation of the wood exceeded 80 %. This result shows the reasons of emergence of defects of the maple wood after the gluing. Therefore, when gluing maple wood sheets, it is recommended to sand the surface before placing a layer of glue with a P80-type abrasive paper, and to place the layer of the glue after the removal of dust, and in order to ensure the proper bonding, to apply the bonding pressure of at least 0.5 MPa. |
