| Résumé : |
Pigments are materials that change the colour of transmitted or reflected light by reflecting a specific wavelength of light while absorbing other wavelengths. In other words, they separate light into different fractions, rejecting only the fraction of the specific colour of the pigment.
Most pigments used are dry colourants, usually ground into a fine powder. The partiale size distribution (PSD) plays a very important role in how light reacts alter hitting a pigment.
Due to their special characteristics, pigments are used as colouring in many different applications. For example, they are usect in paint, fabric and textiles, ink, food, plastics, cosmetics and many other applications. Pigments are milled very fine as the colouration intensity depends on the fineness of the materials.
Hosakawa Alpine has a large variety of milling equipment to process pigments based on the relevant task. The process may be an effective size reduction (milling) if the pigment is, for example, a mineral pigment coming from a mine. It may also be a 'simple' de-agglomeration if the pigment comes from a chemical crystallisation process. It is also possible that the pigment already has the desired PSD and the milling equipment is only used to guarantee a final fineness.
In the selection of the right milling equipment other factors also have to be considered, such as the material characteristics : tendency to stick, abrasiveness, hazard class and others. Hosakawa Alpine has developed the fluidised bed opposed jet mill AFG for ail of these challenges.
The AFG mill has a high turbulence in the mill chamber with no temperature increase, making it the most suitable solution for sticky products. The mill chamber is easily accessible, making it very easy to clean. |
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Creating colour in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 207, N° 4633 (08/2017)
