[article]
Titre : |
EnvironOxide - modifying natural processes to produce high-quality iron oxide pigments |
Type de document : |
texte imprimé |
Auteurs : |
Charles Hoover, Auteur |
Année de publication : |
2018 |
Article en page(s) : |
p. 28-29 |
Langues : |
Anglais (eng) |
Catégories : |
Oxyde de fer Pigments métalliques
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Index. décimale : |
667.2 Colorants et pigments |
Résumé : |
For centuries mankind has utilised naturally occurring iron oxides as colouring agents. It is only in the last century that people have developed ways to chemically synthesise these natural reactions. More recently, the Hoover Color Division of Cathay Industries has worked in conjunction with Won Oxide Recovery to modify a naturally occurring process to produce a series of unique iron oxide pigments. Not only is this EnvironOxide® range a good source of colour, it is also a by-product of a successful reclamation project.
Most people recognise that sulphur is a major contaminant in coal. As coal is burned, sulphur is released into the atmosphere where it combines with moisture to produce acid rain. Coal with even higher sulphur levels is unsaleable and left at the mines in overburden piles. What most people fail to recognise is that the sulphur in coal is not elemental sulphur but an iron sulphide which is more commonly referred to as the mineral Fool's Gold. When Fool's Gold comes into contact with water it dissolves, becoming sulphuric acid. A serious environmental condition is created when this acid migrates into streams and rivers, killing off both plants and animals. |
Note de contenu : |
- Sustainably sourced iron oxide
- Colour strength versus visual differences
- The environoxide process
- Fig. 1 : Just like other naturally occurring yellow iron oxides, EnvironOxide Yellow (left1 can be heat-treated or "burnt" to produce a red colour, EnvironOxide Red lright)
Fig. 2 : An example of EnvironOxide yellow and red used in a transparent metal coating
- Fig. 3 : Here, you can see various red iron oxides tinting a TiO2 base at equal loadings.All of the transparent iron oxides in the above example are weaker than a similar coloured opaque iron oxide, despite similar purity and higher surface areas
- Fig. 4 : EnvironOxide Red, transparent-synthetic red, transparent-natural red and opaque-synthetic red. The quality of the transparency between pigments can be evaluated by using a simple dE calculation, where the standard is the black substrate and the sample is the pigment in a coating at equivalent contrast ratios. In this example, the transparent - synthetic iron oxide has the smallest dE and visually the "cleanest" transparency
- Fig. 5 : While currently slightly "milkier" than synthetically produced transparent iron oxides, EnvironOxide products are "cleaner" than the traditional Umbers, Siennas and Ochres in a transparent coating. Red shades also have the heat stability needed for powder and coil coatings applications
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En ligne : |
https://drive.google.com/file/d/17vhFKO5SBd7nuFbgI3J3Vv5YZLYB5rxo/view?usp=drive [...] |
Format de la ressource électronique : |
Pdf |
Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30917 |
in POLYMERS PAINT COLOUR JOURNAL - PPCJ > Vol. 208, N° 4643 (08/2018) . - p. 28-29
[article]
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