Modification of birch wood surface with silane coupling agents for adhesion improvement of UV-curable ink

UV digital inkjet printing has become a popular surface decoration method for wood-based furniture due to its high efficiency and environmental friendliness. However, the bonding interface between the UV coating and wood surface is weak and results in poor printing durability. In this study, birch wood surfaces were treated with three silane coupling agents, namely γ-methacryloxypropyl trimethoxy silane (KH570), triethoxy vinyl silane (KH151) and 3-glycidyloxypropyl trimethoxy silane (KH560), to improve surface bonding efficiency with UV coating. After saline treatments, the water contact angle of the wood substrates increased from 58° to greater than 100°. The bonding strengths between the UV coating and wood surface treated with 200 g/m 2 KH570, KH151 and KH560 were enhanced to 5.91 MPa, 5.42 MPa and 1.88 MPa, respectively, comparing with the untreated sample of 1.3 MPa. FTIR results indicated that all silane coupling agents could be grafted onto the wood fibers at the substrate surface and KH570 was able to participate in UV curing process. SEM imaging showed that a layer of KH570 was tightly attached to the wood substrate surface and seamlessly connected to the UV coating, thus the adhesion of UV ink was greatly improved.