Effect of Polyurethane Non-Transparent Coating Process on Paint Film Performance Applied on Modified Poplar

Whether modified poplar can obtain a qualified or even excellent finishing effect on European and American furniture is worthy of deep study. To evaluate whether the conventional non-transparent coating process is suitable for modified poplar, a multi-level hybrid orthogonal experiment method was carried out to start research on how factors affect the paint film performance of the non-transparent coating process. The effect of experimental factors and levels on paint film performance is pointed out, and the optimal factors and levels are found. Parameter optimization of the polyurethane non-transparent finishing process based on modified poplar is carried out. An application basis was provided for the extensive use of modified poplar wood as a substrate in the European and American furniture markets. The conclusions are: (1) gloss of paint film can be improved by increasing the number of nitrocellulose (NC) lacquer transparent topcoats, (2) adhesion and thickness of paint film can be improved by polyurethane (PU) sealing primer, (3) the initial paint film’s abrasion is influenced efficiently by the coating process and coating sanding. PU sealing primer has an efficient influence on the later abrasion of paint film. The effect of modified poplar surface pretreatment on the mass loss of paint film tends to be stable.

Water-Repellent Characteristics of Beech Wood Coated with Parylene-N

In recent years, awareness regarding sustainability and the responsible usage of natural resources has become more important in our modern society. As a result, wood as a building material experiences a renaissance. However, depending on the use case, protective measures may be necessary to increase wood's durability and prolong its service life. The chemical vapor deposition (CVD) of parylene-N layers offers an interesting alternative to solvent-based and potentially environmentally harmful coating processes. The CVD process utilized in this study generated transparent, uniform barrier layers and can be applied on an extensive range of substrates without the involvement of any solvents. In this study, European beech wood samples (Fagus sylvatica L.) were coated with parylene-N using the CVD process, with paracyclophane as a precursor. The aim of the study was to analyze the water absorption of beech wood, in relation to the different layer thicknesses of parylene-N. Therefore, four different coating thicknesses from 0.5 to 40 μm were deposited, depending on the initial amount of precursor used. The deposited layers were analyzed by reflection interference spectroscopy and scanning electron microscopy, and their chemical structures and compositions were investigated by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Due to the chemical structure of parylene-N, the deposited layers led to a significantly increased water contact angle and reduced the water uptake by 25-34% compared to the uncoated reference samples. A linear correlation between layer thickness and water absorption was observed. The coating of wood with parylene-N provides a promising water barrier, even with thin layers.

Preparation of a Fast Water-Based UV Cured Polyurethane-Acrylate Wood Coating and the Effect of Coating Amount on the Surface Properties of Oak (Quercus alba L.)

A fast water-based ultraviolet light (UV) curing polyurethane-acrylate (PUA) wood coating was prepared in the laboratory, and applied on oak (Quercus alba L.) at different coating amounts. The PUA wood coating can be fast cured within 22 min, which highly improved the drying speed compared to normal water-based wood coatings (often higher than 35 min). The coating amounts affected the coating properties after curing on oak. With the increase of coating amount, the adhesion, hardness and gloss value of surface increased to different extents. Meanwhile, the surface of sample became smooth gradually because the voids of the oak were filled. Thus, higher coating amount resulted in better coating properties. However, no significant increase of penetration depth was found. During curing, the hydroxyl groups of the wood reacted with the coating. The optimal parameter in this study was the coating amount of 120 g/m², where the adhesion reached 1 (with 0–5% cross-cut area of flaking along the edges), with the hardness of 2H and the gloss of 92.56°, which met the requirement of Chinese standard GB/T 18103–2013, and could be used for engineered wood flooring.