Advantages: 1 mixing and dispersion at the same time; 2 operation is simple and convenient.
Disadvantages: difficulty in color change.
Four working states:
2. Grinding media
Steel ball, Al2O3, ZrO2
3. Quantity of charge
Paint increased by 5~10%
4. Composition and experimental determination of ball mill abrasives
The binder in the paint can actually be regarded as a dispersant to prevent flocculation of the pigment. The lowest amount of binder can achieve both the lowest viscosity and the highest pigment volume to meet the requirements of the dispersion stage.
The best abrasive composition can be obtained by Daniel's flow point measurement as follows:
(1) A paint having a solid content of 55% was diluted with a solvent into a resin solution of 10%, 15%, 20%, ..., 50% solid content.
(2) Accurately measure 20 g of pigment in a beaker, add the resin solution to the pigment, and stir with a glass rod to record the volume of the resin solution consumed when the Daniel flow point is reached.
(3) Plot the volume of the resin solution consumed for each resin solution concentration.
The lowest point of the flow point U curve corresponds to the optimum composition of the abrasive material obtained during dispersion.
5. Practical considerations for the composition of the abrasive
Daniel's flow point method is reliable and can achieve the highest grinding efficiency, but it is easy to have three problems in industrial production:
(1) Due to the low viscosity of the paint in the paint, the equipment wear is relatively obvious.
(2) The binder content in the millbase is too low, which may result in "solvent migration" and coarsening when further thinning.
(3) The feed pump is difficult to transport due to the thicker grouting paint containing pigment.
A resin concentration slightly higher than the lowest flow point can be used in actual production.
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