Most dispersants achieve the effect of loosening the colour filler through a process of moisture, grinding and loosening, coupling and encapsulation stabilisation. However, in waterborne coatings, the more expensive waterborne coating dispersants cannot be used either for cost control reasons.
Principle of waterborne paint dispersants
The main wet dispersants currently on the market are anionic and non-ionic. They are based on the principle of low surface tension and rapid wetting of the pigment particles, followed by high shear forces such as relaxers, grinders and the formation of semi-flocculated (or controlled flocculation) relaxers of the pigment particles.
Properties of waterborne paint dispersants
At present, when the viscosity of the paint is high, pigment resistance to coarsening and severe flocculation do not occur, but poorly controlled viscosity over time can cause problems. Some use coupling agents as dispersants in waterborne paint dispersants, where two different substances are bonded together through hydrophilic and sulphur-containing groups.
The advantages of this approach are:good overall performance, looseness, low dosage and increased adhesion of the paint, but the disadvantage is that it is not part of the de-bonding group and is not suitable for high coating colours.
Selection of dispersants for waterborne coatings
After research and practice, it is recommended to use dispersants capable of flocculation in waterborne coatings. Due to this the advantages are: good colour vibrancy and good gloss for pigment and filler development. In pure emulsion systems, however, we advocate the use of charge-repelling dispersants that enhance charge repulsion. Such as neutral amine salts and polycarboxylate dispersants. There are now some on the market that have been mixed with polyols, surfactants, which are very wet and breathable.
We are advised to use some polymer types with the dispersant blend in the waterborne coating dispersant with the deflocculation effect, which will work better. It is also advocated that we try to use some thickening agents that do not affect the gloss and do not thicken afterwards.