Improved facade coatings / Frank Ludwig in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 195, N° 4492 (09/2005)

[article]  inPOLYMERS PAINT COLOUR JOURNAL - PPCJ > Vol. 195, N° 4492 (09/2005) . - p. 30-34 Titre : Improved facade coatings Type de document : texte imprimé Auteurs : Frank Ludwig, Auteur Année de publication : 2005 Article en page(s) : p. 30-34 Langues : Anglais (eng) Catégories : Chlorure de polyvinyle Copolymère styrène acrylique Formulation (Génie chimique) Humidité -- Absorption:Eau -- Absorption Perméabilité Polyacryliques Polymères en émulsion Résistance à l'humidité:Résistance à l'eau Revêtements en bâtiment:Peinture en bâtiment Silicones Les silicones, ou polysiloxanes, sont des composés inorganiques formés d'une chaine silicium-oxygène (...-Si-O-Si-O-Si-O-...) sur laquelle des groupes se fixent, sur les atomes de silicium. Certains groupes organiques peuvent être utilisés pour relier entre elles plusieurs de ces chaines (...-Si-O-...). Le type le plus courant est le poly(diméthylsiloxane) linéaire ou PDMS. Le second groupe en importance de matériaux en silicone est celui des résines de silicone, formées par des oligosiloxanes ramifiés ou en forme de cage (wiki). Vapeur d'eau Index. décimale : 667.9 Revêtements et enduits Résumé : The author explains how with the addition of special emulsified silicone resins has resulted in facade coatings with an improved water vapour permeability. At all times people have been striven to protect their buildings well. In the past they mainly used silicate paints. Nowadays emulsion-based paints are commun for this purpose. During the 60s acrylic polymer emulsions appeared on the market. They are the foundation of modern coatings and have replaced silicate paints in many applications. The advantages are faster drying, good adhesion on non mneral surfaces, better pigmentation and simple handling. Standard formulations with 15-22 polymer emulsion (active matter content)lead to closed films with excellent weather resistance and very low water absorption. Their water resistance compared to silicate paints was a great progress. But there are still damages at facades - and this exhibits the system's limits. Construction defects at the roof or missing protection of the foundation can cause the migration of water into the masonry. In this situation the missing water vapour permeability becomes a great disadvantage. The coating will not allow water, to escape by diffusion. As a resukt blisters form and flaking can occur. Finally there is no more protection for the masonry and decomposition will take place. To solve this problem, facade coatings with an improved water vapour permeability have been developed. These exhibit a low film tension, achieved through a special pigmentation and a lower polymer emulsion content. The coating offers a porous structure and therefore is diffusionable. Unfortunately the water absorption increases and driving rain can cause moist masonry. To reach an additional water protection special emulsified silicone resins have to be added. The resulting silicone resin emulsion paints conbine both properties, water resistance and water vapour permeability. This is the most effective protection for buildings. Note de contenu : - Influence of pigment volume concentration and polymer emulsion - Evaluation of the water absorption - Evaluation of the water vapour diffusion - Evaluation of the dirt pick-up - Influence of hydrophobing agents - Early rain resistance and dosage of silicone resin emulsions Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=27620 [article]

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