The development of biomaterials-based adhesives is one of the main research directions for the wood-based material industry. In previous research, tannin and sucrose were used as adhesive to manufacture particleboard. However, the reaction conditions need to be optimized. In this study, sulfuric acid was added to the tannin–sucrose adhesive as a catalyst to improve the curing process. Thermal analysis, insoluble mass proportion, FT-IR, and solid state ¹³C NMR were used to investigate the effects of sulfuric acid on the curing behavior of tannin and sucrose. Thermal analysis showed weight loss and endotherm temperature reduced from 205 and 215 to 136 and 138 °C, respectively, by adding sulfuric acid. In case of the adhesive with pH = 1.0, the insoluble mass proportion achieved 81% at 160 °C, which was higher than the reference at 220 °C. FT-IR analysis of the uncured adhesives showed that adding sulfuric acid leads to hydrolysis of sucrose; then, glucose and fructose converted to 5-hydroxymehthylfurfural (HMF) and levulinic acid. Dimethylene ether bridges were observed by FT-IR analysis of the cured adhesives. The results of solid state ¹³C NMR spectrum indicated that 5-HMF participated in the curing process and formed methylene bridges with the C8 position of the resorcinol A-rings of tannin, whereas dimethylene ether bridges were detected as a major chemical chain of the polymer. Lab particleboards were produced using 20 wt % resin content at 180 °C and 10 min press time; the tannin–sucrose adhesive modified with sulfuric acid to pH = 1.0 exhibited better performance than the unmodified tannin–sucrose adhesive; the properties of the boards fulfilled the requirement of Japanese Industrial Standard (JIS) A5908 type 15.

Natural wood textures are appreciated in most forest products industries for their appealing visual characteristics including grain and color, but also their fine surface tactile sensation. The following presents an ultraviolet (UV)-curable inkjet technology printing 3D wood texture on wood-based substrate by image processing and surface treatment. The UV printing was created from scanned digital images of a real wood surface and processed in graphics software. The images were converted to grayscale graphics by selecting color range and setting the parameter of fuzziness. The grayscale images were printed as 3D texture height simulation on the substrates and coated by printing the color images as texture mapping. Based on these wood texture digital images, the marquetry art is also considered in the images processing design to increase the artistry of the printed materials. The medium-density fiberboard (MDF) coated printing marquetry surface replicate realistic natural 3D wood texture surface layers on wood-based panels and imitated the effect of handcrafted wood art works. This study proves that printing 3D texture surface material is creative and valuable with ecologically friendly, low-consumption UV-curable inkjet technology and provides a feasible and scalable approach in flooring/furniture/decorative architectural panels.

The structural properties and whiteness of the substrate surface markedly effect printing quality and are closely related to the primer coating processes. Herein, four different roller coating schemes were applied on MDF surfaces to change their structural properties and color, and the whiteness, gloss, and roughness properties of the substrate surfaces were characterized for UV inkjet printing. Data analysis was conducted to explore the effects of these variables on the color reproduction, relative contrast, and printing gloss of the MDF substrates. The results showed that, according to CMYK, L*a*b* values and spectral reflectance data, the finishing of the MDF substrate with a 40 g/m² layer of transparent primer combined with three layers of white primer at 20 g/m² per roll coating layer had the best color reproduction effect for UV inkjet printing. Regarding the effects of relative contrast, the correlation with whiteness and glossiness was significant, while the correlation with glossiness was minor. The inkjet printing gloss value was positively correlated with substrate primer surface whiteness, while it was negatively correlated with roughness. When the surface whiteness of the substrate was relatively high, the roughness was lower and the printing effects were glossier. We sought to optimize the printing effects of all aspects of the MDF substrate by primer coating. The results of this work provide a feasible application method to improve printing quality and enhance the added value of low-quality boards, as well as to further expand the application of UV inkjet printing in the wood decoration market.

Calcium carbonate (CaCO₃) is a widely used inorganic filling pigment used in coatings, and it is known for its nontoxicity, odorlessness, and environmental friendliness. The application of CaCO₃ as a filler can effectively reduce raw material costs, and optimization of the filler formula enhances the coating film performance. In this study, oak planks were prepared as substrates for water-based inkjet printing. Three composite water-based primers with different TiO₂-to-CaCO₃ ratios and a polyurethane resin primer were used to prepare the substrate for the printing surface. The properties of the water-based primer coating and the water-based inkjet printing coating were characterized and analyzed via Fourier-transform infrared spectroscopy, video-based contact angle analysis, and environmental scanning electron microscopy. The aim was to investigate the effects of the composite waterborne primer coatings on the ink absorption and coloring properties of the interface between wood substrates and waterborne inkjet coatings. Sample WDCC-3^#, with a TiO₂-to-CaCO₃ ratio of 15:35, exhibited the most comprehensive characteristics. The wood surface coated with 15 g/m² of the polyurethane resin primer and 15 g/m² of WDCC-3^# exhibited a 5.8° contact angle of the water-based ink, first-grade adhesion, 4 H hardness, 70.52 whiteness value, and a roughness of ~2.33. The surface of the printed water-based inkjet-coated substrate was uniform and smooth, featuring rounded and transparent edges of the water-based ink droplets and a small CMYK color difference value. Therefore, the composite waterborne primer, incorporating TiO₂ and CaCO₃ in specific ratios, can be effectively combined with waterborne polyurethane primer coatings. This combination significantly improves the interfacial compatibility between the oak surface and waterborne inkjet coatings, leading to enhanced ink absorption on the oak plank surface during printing. This results in a high degree of color reproduction and clearer printed images. Overall, this study provides valuable insights for the development of primer programs for the industrial application of waterborne digital inkjet technology on wood products.

Wood surface staining suffers from volatile organic gas (VOC) emissions and uneven staining at knots, and these environmental and decorative performance issues are the main restrictions in the application of wood products, indoors and outdoors. Herein, the method of wood-based panel surface staining is presented for improving environmental and decorative performance using environmentally friendly water-based inks, water-based primers, and digital inkjet coloring technology. The wood-based panels’ dye coatings were prepared with oak plank as the sample substrate, a one-component water-based primer as the interfacial adhesive, and a water-based ink as a coating agent. The application amount of water-based primer was 15 g per square meter, applied twice by a roller, and the coating thickness reached approximately 20 μm. The influence of the one-component water-based primer on the interfacial properties of water-based inkjet coatings was investigated via Fourier-transform infrared (FTIR) spectroscopy, a video contact angle analyzer, and environmental scanning electron microscopy (SEM). The results showed that the one-component water-based primer connected the plain board to the inkjet-printed coating. The addition of a water-based primer coating reduced the contact angle of the wood surface from 41.69° to 37.28° and increased wettability. This helped enhance the adhesion of the water-based inkjet coating, and the primer treatment in the semi-closed state covered the scar defects of the plain board while preserving the path of grain holes on the wood surface. With image editing and inkjet dyeing, the surface of the oak plank obtained a uniform staining effect on the primer coating while maintaining the original natural pore texture of the wood. This study proves that a one-component water-based primer pretreatment process for water-based inkjet printing coatings on wood surfaces has excellent modification ability and interface adhesion. It provides a feasible method of color modification for artificial panel surfaces.

Purpose: This study aims to propose a novel approach to address the high costs and complex processes of traditional glasses-free three-dimensional (3D) furniture decoration. It uses ultraviolet inkjet printing technology to achieve a glasses-free 3D decorative effect on furniture surfaces. Design/methodology/approach: By leveraging the microlens array principle, transparent UV ink was printed onto a transparent substrate to simulate a micro-lens matrix. In contrast, a micrographic array was printed on a secondary substrate (or the reverse side of the transparent substrate). Their superposition generates autostereoscopic depth perception via the Moiré effect. Experimental validation compared two matrix arrangements: square-arranged (with circular or square textures) and hexagonal-arranged (with hexagonal or circular textures). Each was paired with micro-text arrays in an “A” pattern. Four furniture surface design concepts were ultimately implemented, incorporating floral motifs, traditional Chinese elements, Memphis-style patterns and gradient designs. Findings: Results demonstrate that: Square-arranged matrices achieve optimal Moiré magnification at angles of 2–6°, with theoretical and experimental Moiré pattern period (M) deviations < 5 mm; Hexagonal textures outperform circular ones in image clarity and magnification efficacy; Square-textured matrices yield superior magnification quality versus circular equivalents. The printed furniture samples exhibited vibrant colors, distinct textures and dynamic 3D effects observable from multiple angles. Originality/value: This study confirms the feasibility of using UV inkjet printing to create textured matrices, integrating glasses-free 3D effects into furniture panels. This approach enables cost-effective, glasses-free 3D furniture decoration, thereby expanding possibilities for personalized surface aesthetic design.