Pigment Dispersion on The Performance of Coatings and Pastes

Pigment Dispersion on The Performance of Coatings and Pastes

Some common problems people encounter when dispersing organic pigments are flocculation, insufficient color or clarity, and poor rheology or stability. Attached are the possible causes of these problems and their elimination through the correct selection of various raw materials and dispersing machinery and equipment.

Theoretically, “well dispersed” means that each pigment particle in the system is completely de-flocculated, that is, each pigment particle is wrapped by a thin layer of paint base or solvent.
Pigment dispersion quality can affect many important coating properties:
● Gloss (if the pigments are optimally dispersed, this directly increases the gloss)
● Weathering and chemical resistance (Weathering and chemical resistance will also be mainly determined by the choice of paint base. Appropriate pigments or extenders, if optimally dispersed, can also improve the chemical resistance of the paint base)
● Storage period (The storage period of a coating system depends largely on the quality of pigment dispersion. This largely depends on the stability of the dispersed paint base during the dispersion process or the ratio of paint base to solvent)
● Color, tinting power, transparency and hiding power (all these properties depend largely on the surface of the pigment used i.e. “optimal dispersion”. Complete dispersion of the pigment is essential for hiding power In the case of pigments, it can lead to increased hiding power, making the color paste more intense (without flocculation); in the case of transparent pigments, it can lead to better transparency.)

There are four (more or less) simple ways to determine pigment dispersion quality:
● Fineness meter (simplest and most commonly used method. One of the biggest advantages of the fineness meter is that it is fast. It can only indicate the size of the largest pigment agglomerates, but cannot provide information on particle size distribution)
● Electron Microscopy (accurate, but expensive and time-consuming method. It is not at all suitable for daily practical use)
● Coulter Counter ( It provides a good idea of the particle size distribution in a pigment dispersion and is a relatively easy operation to perform compared to electron microscopy)
● Tinting power (simple but important method. This method makes it easy to determine whether the pigment has been optimally dispersed)

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