New additive to eliminate pinholes for water-based coating formulations / Jim Reader in COATINGS TECH, Vol. 18, N° 3 (03/2021)  

[article]  inCOATINGS TECH > Vol. 18, N° 3 (03/2021) . - p. 30-37 Titre : New additive to eliminate pinholes for water-based coating formulations Type de document : texte imprimé Auteurs : Jim Reader, Auteur ; Jos van Oosterwijk, Auteur ; Caixuan Xu, Auteur ; Ye Dai, Auteur ; Ruediger Mertsch, Auteur ; Shauna McAuliffe, Auteur ; Jianchang Tang, Auteur Année de publication : 2021 Article en page(s) : p. 30-37 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Antimousse Automobiles -- Revêtements Couche de base Dépôt par pulvérisation Encre Formulation (Génie chimique) Piqures (défaut) Revêtements -- Défauts Revêtements en phase aqueuse -- Additifs Revêtements organiques Surfactants Tension superficielle Vernis bi-composant Viscosité Index. décimale : 667.9 Revêtements et enduits Résumé : Pinholes are a problem for formulators developing fast-drying, water-based coatings, especially in coatings cured at high temperature and applied at high wet film thickness. Pinholes are often caused by air or solvent vapor release from the film when the coating is too viscous to flow back and repair the holes. Pinholes also occur in baked coatings, as the trapped vapor regains mobility when the coating softens under heating, before crosslinking hardens the film, preventing flow back into the voids. Hydrocarbon-based defoamers help eliminate the foam and pinholes in these formulations, but their limited compatibility results in lower gloss, poor leveling and surface appearance. This paper describes a new additive that combines both deaeration of microfoam and modified surface drying for pinhole elimination. This new additive shows comparable pinhole elimination compared with hydrocarbon-based defoamers, but without compromising formulation compatibility or final coating appearance. Note de contenu : - New additive development - Fig. 1 : Pinholes in a spray applied automotive OEM basecoat - Fig. 2 : bubble release and pinhole formation in an applied film - Fig. 3 : Molecular defoamer mechanism to eliminate microfoam - Fig. 4 : Change in film fluidity of a water-based coating during drying - Fig. 5 : Influence of surfactants on open time of water-based, 2K clearcoat new anti-pinhole additive - Fig. 6 : a) Surface tension reduction with LA-W 1814 and b) Foam control in water-based primer - Fig. 7 : The "wedge" application test - Fig. 8 : Minimum film thickness for pinhole formation - Fig. 9 : Foam control and surface appearance of white basecoat sprayed with different anti-pinhole additives - Fig. 10 Panels of white basecoat containing different anti-pinhole additives - Fig. 11 : Foam and surface appearance of silver basecoat panels after clearcoat Application - Fig. 12 : a) Flop index and b) wave scan of silver basecoat panels after clearcoat application - Fig. 13 : Images of water-based plastic coating applied onto glass after high-speed stirring. (Panels are viewed from back of panel with backlighting) - Fig. 14 : Foam control in water-based packaging ink - Fig. 14 : - Table 1 : White basecoat formulation - Table 2 : Blue packaging ink formulation En ligne : https://drive.google.com/file/d/11XvghQD3eob_XhUd0fbNTfayVNfj_h-N/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35527 [article]

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