Principle of Dispersant (Using in Coating)

Principle of Dispersant (Using in Coating):

1. In Mechanical method, the most basic purpose of pigment dispersion in the medium is to disperse lipophilic concentrated particles due to drying during pigment manufacturing. As the fineness of the particles decreases, the exposed surface area of the particles increases, which improves the optical properties of the pigment, such as coloring properties, gloss, brightness, hiding power, or transparency.

2. In general dispersant grinding systems (such as inks and coatings), resin is one of the ingredients of the formulation. However, resins and dispersants will compete with each other in pigments. The resin also affects the ability of the dispersant to adsorb onto the pigment surface. The resin and dispersant will compete with each other to absorb the pigment surface. However, the difference between the dispersant and the resin is the speed at which the dispersant reaches the pigment surface. The dispersant not only has a strong adsorption force for the pigment, but also has good contact with the solvent.

The resin on the pigment surface actually only has a moisturizing effect. Does not adhere to the pigment surface for a long time. Over time, the resin will slowly leave the pigment surface and cause flocculation. However, the presence of the resin still prevents the dispersant from anchoring the pigment surface.

Therefore, when selecting a resin, the film-forming function brought by the resin should be considered, and it is not necessary to select a good wettability or other abrasive resin. In addition, it must be considered whether the resin content in the ground substrate is sufficient. Maintain formula stability.

3. The use of dispersant in the grinding base material, compared with the traditional grinding base material, the most critical adjustment of the preparation is the concentration of the resin solution. The resin concentration in traditional grinding media is high and the pigment loading is small. Although reducing the resin concentration can reduce the viscosity of the dispersion medium itself and increase the pigment loading, this dispersion system is unstable and cannot be practically used in production.

If a good dispersant is used, the dispersion system can be stabilized at a lower resin concentration, which greatly increases the pigment loading in the grinding base, and reduces the space barrier caused by the solvation chain of the dispersant in the solvent . Space obstacle. The suction between particles greatly reduces the mill viscosity, which is one of the reasons for the increased pigment loading.

Under the action of the dispersant, the increase in the pigment filling amount varies with the dispersion system, but during the adjustment process, the viscosity of the grinding binder should be kept moderate.

4. Pigment stability theory & the stability of pigment dispersions. There are two main mechanisms: electrostatic stability and site stability. Both of these mechanisms must molecularly adsorb the pigment surface.

iSuoChem® Dispersant is used for masterbatch, organic pigment, coatings, paints (solvent based) and offset inks & Publication gravure inks.