6. Extinction powder


Extinction powder itself is not difficult to disperse. It is micronized in advance at the time of production. Some have surface wax treatment, some have no polar hydroxyl. However, the dispersion problem of extinction powder comes from the application requirements.


Some require that the matt coating can be used with a formula to adapt to a variety of construction methods, such as spraying to the same gloss;


Some requirements in high temperature and high humidity, extinction uniformity is not affected;


Under the condition of low viscosity, the extinction powder has the minimum settlement;


Some require the highest transparency;


Some requirements have excellent friction resistance, and the introduction of hard quartz powder, so it needs to be dispersed together and so on.


This leads to a consequent change in the dispersant. From the traditional wetting dispersant, to the special high Pu dispersant, to the phosphate ester, to the amine salt of the phosphate ester, to other special polymers, are used to disperse the extinction powder. So which is the best? As mentioned before, it depends on what you ask for. One dispersant cannot be expected to solve all the requirements at the same time.


In principle, the wetting agent can improve the flow capacity of the final system; the high-quality dispersant can prevent the settling and control the movement of the extinction powder in the wet film, so it is easier to orient and get uniform extinction.






7. Metallic flash pigments such as aluminum powder and pearlescent powder


The common solution is wetting agent.


They can also be dispersed with a highly dispersing agent compatible with the resin. Control their movement at the same time. These are examples of successful recipes.






8. Determine a main dispersant


Generally, in a certain resin and solvent system, it is recommended to select a suitable main dispersant by such a method:


First of all, four pigments, high pigment carbon black, titanium white, DPP red and common iron oxide red, are dispersed.


To evaluate whether the dispersing agent is difficult for the preparation of the four conventional color masterbatch, for example, whether the viscosity reduction behavior is sufficient.


Evaluate color development intensity


Evaluate storage stability (flow plate and heat storage).


If a dispersant can show good dispersion ability to the above four pigments in this specific system, it can basically meet the requirements of various other pigments. Can be selected as the main dispersant of this system. Of course, special pigments such as iron penetration are still possible exceptions.


This method can also be used to evaluate the comprehensive performance of two different dispersants and find the suitable pigment type for it.


(source: core chemistry)