Why does the white material grinded by the horizontal sand mill change color?

When using a horizontal sand mill to grind the white slurry, it is found that the color of the product changes, why is this? There are generally the following reasons.

1. The quality of the white pigment itself is not up to standard, such as defects in packaging and surface treatment. Please check the white pigment for quality defects first.

2. Formulation problems, such as: dispersant, resin and additive amount problem, dispersant and resin may change during the grinding process, resulting in color change. Long grinding times, reduced particle size of white pigments, and surface passivation may also lead to color changes. This can be tested with a generic recipe and then check to see if there is a problem with your recipe.

3. The problem of the horizontal sand mill. First, grinding white pigments requires the selection of a dedicated horizontal sand mill. The abrasive parts should be very hard and should be made of a white material such as zirconia, which cannot chemically react with the material. Secondly, qualified zirconia beads should be selected as grinding media, and the amount of beads loaded should be determined according to the specific application. Also, when grinding white pigments, other colors that the sander has previously ground must be cleaned. Otherwise, it is easy to cause discoloration.

4. Check if your product is stable under high temperature and oxidized in the air.

In short, the discoloration phenomenon of white pigments ground by a horizontal sand mill can be solved by eliminating them one by one according to the above method.