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Article: Aluminum pigments encapsulated by inorganic-organic hybrid coatings and their stability in alkaline aqueous media.(Report)
- Article from:
- JCT Research
- Article date:
- March 1, 2008
- Author:
CopyrightCOPYRIGHT 2008 Federation of Societies for Coatings Technology. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Introduction
Lamellar aluminum pigments ("aluminum flakes") have been used in solventborne metallic paints or inks for many years (1) due to their metallic appearance and "flop-effect." (2) Recently, growing importance of environmental considerations have led the paint and coatings industry to the development of coating systems with a reduced content of volatile organic compounds (VOC). (2,3) Waterborne coatings are the preferred way to solve the problem. However, since the waterborne coatings are mostly prepared in an alkaline medium, the aluminum pigments react with water:
2Al + 6[H.sub.2]O [right arrow] 2Al(OH)[.sub.3] + 3[H.sub.2] [up arrow]