Cause analysis of unqualified color paste produced by sand mill

Why do some manufacturers use sand mills to produce unqualified colorants? Some customers have heard that they have been confused about the accuracy of the grinder they purchased. What are the common causes of non-compliant abrasive fineness? How to solve?
One of the reasons: pigment particles are difficult to disperse, such as carbon black, iron blue, etc.
Treatment method: In production, first, disperse after ball mill or three-roll machine grinding; second, use dispersant, carbon black and other solvents for dispersion treatment. The above method may affect the yield, so it is mainly to surface treat the pigment to improve the dispersion of the abrasive particles. The reason is that the fineness of the paint paste itself cannot meet the requirements of the color paste.
Treatment method: The fineness of the paint paste should meet the fineness requirements, otherwise the fineness cannot be guaranteed. Therefore, the specified fineness of the millbase should be used. In order to meet the requirements of the grinding paste, the user can find out the reason according to the actual situation, so that the fineness of the grinding paste can meet the requirements and improve the work efficiency.
Reason 3: The impurity content in the pigment is too high and it is difficult to grind, such as mixing with impurities such as paint, fiber, dust, and fine sand.
Countermeasures: Rely on the paint supply department to strengthen management, prohibit mixing, and ensure product quality; in the slurry workshop, strengthen paint filtration, pay attention to remove impurities in the powder; three-rollers disperse mixed impurities, use full hoppers, residual hoppers, or use single Roller mills in series for filtration.
Reason 4: The fineness of the pigment itself exceeds the fineness required by the paste and cannot be polished. In many cases, this is due to the original pigment particles being finer than the desired slurry.
Countermeasures: further process and crush the pigment to make it pull out a diameter smaller than the required paste fineness, because the dispersion process of paste grinding cannot solve the problem of further reducing the original particles.