| Résumé : |
The author discusses a new additive technology for waterborne iron oxide pigment concentrates.
In decorative coatings, the use of pigment concentrates is a modem and flexible wayto produce coloured paints. Especially in waterborne applications, these concentrates have to be suitable for a broad range of different binder technologies. Because of that, the concentrate formulations are usually free of binders and feature a broad compatibility. Furthermore, the demands in terms of storage stability, colour strength and cost efficiency are very high. These demands are addressed directly to the used additive technology. The additive has to induce outstanding viscosity reduction to achieve the highest pigment loads and the most economic grinding. It has to stabilise the pigments over a long period of time without any change in viscosity and it has to develop maximum colour strength to avoid any waste of expensive pigments.
The most important pigment class in decorative coatings are the iron oxides. Iron oxides are not difficult to wet because of their shape. Iron oxide yellow tends to give dilatant rheology, which can be a disaster when it comes to automatically dosing in a dispensing machine. Iron oxide red, on the other hand, tends to increase the viscosity of pigment concentrates over time.
This paper elucidates to different structures of wetting and dispersing additives, which could be used in waterborne, binder-free pigment concentrates for iron oxides and their performance. It is focused on the stability and the wetting of the pigments, which are reflected by the viscosity reduction, the storage stability of the pigment concentrates and the colouristic properties. For the characterisation of the wetting behaviour and the dispersing efficiency, the zeta potential has been used. In the end, advice and guidelines for formulating iron oxide pigment concentrates will be given. |
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The best for red and yellow in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 210, N° 4663 (08/2020)
