In last month’s column of “Formulating with Mike,” we discussed how varying the tail length (amount of ethoxylation) with a fixed hydrophobic head had an effect on properties of the pigment dispersion and the final tinted coating. In this month’s column, we will look at how the amount of actual dispersant added on pigment solids will have an effect on properties. I would like to thank Alann de O.P. Bragatto, Brandon L. da Silva, and Fabrício G. Pereira for generating the data for this article.
Last month, we kept the affinic hydrophobic group fixed, and four different non-ionic surfactants were evaluated with different degrees of ethoxylation. 16, 18, 25, and 54 moles of ethoxylation were tested and identified as surfactant 16, 18, 25, and 54, respectively. We determined that 18 moles of ethoxylation was optimum. This month we will test this dispersant at different levels. We prepared surfactant level versus viscosity graphs of the four dispersants as shown in Figure 1.