Pigments are designed and produced to be insoluble particles used to impart colour in a variety of materials. The diverse range of its chemistries, the end use requirements, and the broad range of colours available create a challenge for chemists when incorporating them, being stability and settling one of the many factors to consider. The first steps in the pigment dispersion process are wetting and separation of the pigment. However, if the pigment dispersion is not properly stabilized, flocculation will result.
One of the main mechanisms to obtain pigment stabilization is charge repulsion, in which particle surfaces with like charges repel each other. Properly stabilized pigment dispersions prevent flocculation and agglomeration.
Zeta potential serves as a reference as to how stable the formula will be. Pigment dispersions with a zeta potential between +30 mV and -30 mV have a high probability of being unstable.
In this study, zeta potential was measured by Electrophoretic Light Scattering. Sample was a water dispersion of a pigment used in the automotive industry. Results obtained (see picture) are compatible with a stable dispersion as average zeta potential is -42,3 mV.
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