Briefly pigment dispersion system stabilization in paint
2016.06.20 09:15Has wet paint particles move to liquid paint is continuous, non-volatile film-forming material permanently separation process. Pigments in the paint Decentralized system by two kinds of mechanism to make it stable. The charge stability effect and space steric hindrance or entropy stability.
(1) the charge stability
Is the charge stability as a result of electric repulsion. Electric repulsion is around the electric double layer of pigment particles. Because all the particles are the same Surrounded by a charge, so when the particles get very close, they repel each other.
Usually, in aqueous dispersion system, as a result of pigment particles of high dielectric constant, the stability of the charge is more outstanding, and for solvent coatings , due to the commonly used organic solvent polarity is weak, therefore, the stability of the electric charge effect is not important, the stability of the dispersion system mainly rely on empty The effect of steric hindrance between.
(2) the space steric stability
When big depolymerization of pigment particles into smaller particles, usually to form new surface, a new surface paint being wet, make the pigment particles Surface is thick enough resin coated, because generally paint have a - OH, - COOH, such as polar group, it is easy to form a certain adsorption on the pigment The thickness of the protective barriers, brings to the movement of the pigment particles contact each other collision steric hindrance. Once two pigment particles due to movement and close to each other, The periphery of the coating resin layer will be squeezed and make the entropy decreases, but the tendency of entropy has natural enhancement, so produce entropy repulsion, the relative to the extrusion In the opposite direction of the force that tend to be more close to the pigment particles and separated from each other, this is known as the space steric stability (or entropy).
By Nicole