Study on thickening of water-based inorganic zinc-rich coatings (2)

2 Results and discussion
2.1 Inorganic gel thickener on the thickening effect of water-based inorganic zinc-rich coatings
Elementis' BENTONE series of inorganic gel thickeners are refined lithium-mondite clays that contain EW, DE, LT, DY 4 different organic modified models and are natural inorganic gel thickeners;
high-speed stirring to disperse the above thickeners in deionized water prepared into a concentration of 2% to 14% of the pre-gel, and then in high-speed stirring using different additions in accordance with the method of 1.2 in this paper to prepare 50 g water-based inorganic zinc-rich coating base ingredients. The results of the test viscosity change are shown in Figure 1, in terms of adding a thickening viscosity of 8 g, the thickening effect is sorted from good to poor as LT-DE-DY-EW-RDS. Of all the inorganic gel thickeners tested, the addition failed to multiply the viscosity of the base ingredients of the water-based inorganic zinc-rich coating, the thickening effect was not ideal, the zinc powder sequentium rate with the sit-down time change curve as shown in Figure 2, the coating after the preparation of the static 10 min have occurred a subsidence rate of more than 20%.the charge properties of the substation system is one of the important factors affecting the thickening effect of inorgligic gel thickener. The substation of water-based inorganic zinc-rich coating is mainly composed of high-module silicate, which contains a large number of silicone oxide sol particles, the silicone on the particle surface chooses to adsorption medium OH- and make the surface negatively charged, the inorganic gel thickener structure contains Al3-plus, Mg2-plus, Li-plus, Na-plasma metal oxide intermediate layer, due to insufficient cation charge and the same layer with negative charge. As a result of same-sex rebulation, inorgic gel thickeners and silicone sol particles have a tendency to separate from each other, reducing its thickening effect. The pH of the water-based inorganic zinc-rich coating substate is about 12, and from the parameters of the experimental samples listed in Table 1, the maximum pH of the inorganic gel thickener is lower than the pH of the substitin, so it is not recommended to use in the base material.
, the concentration of inorgligic gel thickener pre-gel is also an important factor affecting the thickening effect. As listed in Table 2 inorgeable gel thickener, BENTONE DE concentration is capped at 14%, significantly higher than several other models, can be prepared into a high concentration of pre-gel, added to the solid substation effect is relatively small, so the thickening effect is better. Adding BENTONELT directly to the zinc powder part of the water-based inorganic zinc-rich coating in the form of powder is much better than preparing a pre-gel to add to the substitline, which is because the amount added to the inorganic gel is no longer limited by the concentration bottleneck of the pre-gel, and the compounding with other thickeners (e.g. hydroxyethyl cellulose) will produce synergies to improve the thickening effect..