Effects of MDF Substrate Surface Coating Process on UV Inkjet Print Quality

Abstract

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.

Effect of TiO2@CaCO3 Waterborne Primer on the Coloring Performance of Inkjet-Printed Wood Product Coatings

“…Coating roughness was assessed using a JB-C roughness tester, and the average of measurements taken at five points on each specimen was taken as the result. The whiteness of the coating, which can affect color deviation in printing [30,31], was measured on the sample's surface using a WSB-2 whiteness meter (Qiwei, Hangzhou, China). Measurements were taken at five areas for each sample, and the average value was calculated.…”

“…Table 5 demonstrates that the adhesion of the TiO2@CaCO3 composite water-based primer is excellent, achieving a level 1 rating in compliance with national coating The introduction of the TiO 2 @CaCO 3 water-based primer coating significantly reduces the color shift of the topcoat coating. However, the adhesion of the primer to the substrate is not as strong as that of the WD4500A water-based polyurethane resin primer because water-based polyurethane resin has excellent permeability and can penetrate the substrate's capillaries, thereby preventing the leakage of pigments or tannic acid [30]. When used as the initial layer in the roller-coating process, the water-based polyurethane resin primer can fully demonstrate its advantages.…”

The Effect of Water-Based Primer Pretreatment on the Performance of Water-Based Inkjet Coatings on Wood Surfaces

“…In recent years, newly developed digital inkjet printing methods have been applied in the wood industry [7,8]. This technology is a noncontact method that enables digitally controlled injections of tiny ink droplets through a printhead into a specified location onto a substrate, accurately depositing a precise amount of ink to create an image [6].…”

Adhesion of Varnish Coatings as a Background for Analogue and Digital Printing Technologies

“…In the former, the pattern carriers are engraved rollers, while in the latter, data in the digital form are transferred to the printhead [4][5][6]. UV varnish products, which are considered environmentally friendly, have been widely used in these technologies [5][6][7][8][9][10]. Their crosslinking occurs via polymerization based on a mechanism of free-radical reaction, which is initiated by UV radiation.…”