[article]
| Titre : |
Sustainable and high performance : New biobased acrylic dispersion to prevent knot staining for wood coating |
| Type de document : |
texte imprimé |
| Auteurs : |
Ziniu Yu, Auteur |
| Année de publication : |
2023 |
| Article en page(s) : |
p. 40-47 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Catégories : |
Adhésion
Biomatériaux
Bois -- Revêtements
Charges (matériaux)
Formulation (Génie chimique)
Noeuds du bois
Polyacryliques
Primaire (revêtement)
Résistance à l'exsudation
Résistance aux taches
RessuageLe contrôle par ressuage (Penetrant Testing en anglais, d'où son abréviation officielle : PT) est une méthode de contrôle non destructif très utilisée dans l'aéronautique, l'industrie de production d'énergie, les transports et les prothèses chirurgicales.
Cette méthode permet de mettre en évidence des discontinuités débouchantes (fissure, crique, etc.) sur tout métal, de nombreuses céramiques et de nombreuses pièces composites.
Cette méthode de contrôle non destructif (CND) est utilisée dans les fonderies, les forges et les unités d'usinage.
Revêtements -- Finition
Revêtements organiques
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
Knots—the circular imperfections in the wood grain—often cause issues in coating appearance due to their high concentration of potent extractives that can degrade a coating system over time. Unfortunately, knots are unavoidable in softwood species, such as pine, which is often used for furniture and cabinetry applications. Knots occur naturally when branches die and become encapsulated as the tree grows. During the encapsulation process, extractives—the tree’s natural resins—seal off the former branch’s location and provide a biological boundary between this area and the rest of the tree. Wood typically contains up to 4 wt % extractives of total weight of the wood. However, in knots, the extractives are concentrated and can reach as high as 40 wt %. When the wood is coated, the knot area is prone to exudate the extractives and bleed through the coating. Combined with the effect of UV radiation oxidizing some of these components, the typical result is brownish discoloration bleeding through the coated surface at the knot area. Figure 1 shows the knots of pinewood, wood extractives, and the resulting knot bleeding effect through the coating. Knot bleeding effects are a problem in the wood coating industry because they can significantly impact the appearance of the coatings, as shown in Figure 1. In addition, bleeding can compromise coating performance, causing a coating to become brittle, crack, or peel. The discoloration over the knots is typically not seen immediately but can take months. The time it takes for the discoloration to appear depends on several factors, including the wood species, environment humidity, temperature, and exposure to UV radiation. |
| Note de contenu : |
- EXPERIMENTAL : Resins and formulations - Knot bleeding tests - Summary of other tests
- TESTING RESULTS AND DISCUSSION : Knot bleeding resistance - Dry-time test - Sandling capability - Adhesion - Block resistance
- Table 1 : Knot bleeding resins comparison chart
- Table 2 : Wood promer formulations
- Table 3 : Resins for topcoats
- Table 4 : Topcoat formulations
- Table 5 : Summary of tests
- Table 6 : Filler studies in primer layer
- Table 7 : Primer block resistance test |
| En ligne : |
https://drive.google.com/file/d/13w9l5CuMy2SGkgC4IX2KLt-v8SqJpRbC/view?usp=drive [...] |
| Format de la ressource électronique : |
Html |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38969 |
in COATINGS TECH > Vol. 20, N° 2 (03-04/2023) . - p. 40-47
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