news

Why do some have good and some have poor viscosity reduction effects when grinding colorants? The phenomenon does occur frequently when testing dispersants in the laboratory. The exact same formula, using different dispersants, can result in significant differences in viscosity. Some viscosities can be very thin, while others can be very thick, or even impossible to disperse.

There are several main reasons, the first of which is the choice of dispersant. Is it appropriate? I know about pigments, including organic and inorganic pigments, carbon black, and so on. The polarity characteristics of different pigment surfaces are different, and it is necessary to choose dispersants with different anchoring groups in order to have good affinity with them.

For example, dispersants with carboxyl groups on the surface of inorganic pigments have better dispersion and degradation effects on inorganic pigments. The surface of organic pigments with acidic groups is mostly resistant to acidity, including carbon black. Most of the carbon black used in the coating industry is also acidic carbon black, of course, there are also alkaline carbon black.

It is best to have alkaline or neutral anchoring groups on these surfaces, which will have a strong anchoring effect on them, in order to disperse them well. The second one is in combination with resin, where different dispersants are combined with different resins, resulting in compatibility issues.

If the compatibility between dispersants and lipids is poor, many dispersants rely on space, while others rely on charge repulsion. To achieve stability, when the relative properties of resin and dispersant are poor, steric hindrance groups are difficult to expand. At this point, the effect of spatial hindrance will be lost. After the loss, the entire system will be in a flocculent state, and there will be a significant thickening phenomenon, with very poor viscosity reduction effect. Different lipid systems may also require the selection of different dispersants.

The third point to note is the amount of dispersant added, which should be evaluated based on data such as the amount of pigment, pigment absorption ratio, surface area value, etc. If the dosage of dispersant is not sufficient, the entire system is not completely dispersed well. At this point, it is in a semi flocculent state, and the reduction effect will be relatively poor. Is it good to add more dispersants? If too much dispersant is added, it may actually have some side effects. Sometimes anchoring groups are also polar groups, which can generate hydrogen bonds and other connections. Apart from other side effects, it is not entirely beneficial for reducing viscosity. So, the amount of dispersant added should be appropriate, just right, which is the best.