It is recommended to add 1%-3% of the finished paint, the amount to be added in aluminum alloy and stainless steel substrate should be increased, depending on the formulation system. Be cautious of using non-acid resistant pigments and multi-vacancy fillers, which may cause darkening and blackening of the untreated aluminum powder surface.
These structural differences will eventually lead to differences in hiding power, tinting power and thermal stability. Nog 033631pm
(a) Rohm and Haas product structure
(b) Market product structure
Electron microscope structure of different covering polymers
Hiding power and tinting power In order to distinguish the difference in hiding ptfe dispersion numbers power of different hiding polymers, first of all, we will discuss different hiding power testing methods. The hiding power can usually be measured by measuring the contrast ratio of the paint film, but this method tends to cause larger errors. Because the contrast ratio depends on the amount of light transmitted by the paint film, and the amount of light transmitted is largely affected by the thickness of the paint film. The thicker the paint film, the lower the light transmission. Therefore, as shown in Figure 20-19: when the paint film is thin (1.5mil or 38.1gm), the thickness of the paint film will be greatly affected due to changes in viscosity and film production speed during the film production process. This leads to greater fluctuations in the test results of the comparative half; and as the thickness of the paint film increases (3ml or 76.2pm), the influence of the paint film thickness on the contrast ratio is reduced, but at this time the paint film itself has a high hiding ability, so It is difficult to distinguish the difference in covering ability of covering polymers.
Comparison of test results of contrast ratio under different paint film thickness conditions
The experiment found (Figure 20-20): Through the tinting strength experiment, the difference in the hiding ability of the hiding polymer can be effectively distinguished. After adding 1/32 volume of the lamp black paste, by measuring the whiteness (Y value) of the 3mil (75pm) film thickness, not only can the reproducible experimental results be obtained, but also the masking polymer can be effectively distinguished. The difference in ability. However, the accuracy of the results of the tinting strength experiment is based on the good color development. Usually, the color development can be judged by the method of finger grinding or roller coating or brushing to observe the color difference in different areas.
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