Oil absorption issue
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One of the products manufactured by our factory, cuprous oxide, is mainly used in coatings. Recently we encountered a problem: compared to foreign products, its fineness is similar, and those from abroad are even finer, but their oil absorption capacity is very low Has it been surface-treated? If so, are there any surface treatments that can reduce oil absorption? Thank you! ! ! This post was last edited by memory1980 on 2009-3-20 13:32.]
Could we consider surfactants with oil-repelling groups?
Previously, when we produced ferric tetraoxide, we applied a hydrophobic and lipophilic treatment to its surface; as a result, the dispersion of the particles improved and their oil absorption capacity increased, with the main reason being the enhanced dispersion of the particles. The particles of foreign products are finer than those of yours, but their oil absorption capacity is lower. Is it because the foreign products have a higher degree of agglomeration?
There are several possibilities: 1) The foreign products may have undergone surface treatment； 2) Different crystal forms ；
1. The oil absorption capacity mainly refers to the specific surface area per unit mass of the powder. It reflects the particle size and surface roughness of the powder, and it also indicates the size of the pores in particles with pores. 2. The impact of oil absorption capacity on the formulation is mainly reflected in the pigment-to-binder ratio design; for the same binder, a higher oil absorption capacity requires more binder, while the opposite is true for lower absorption capacity. 3. Below the CPVC (critical pigment-to-resin ratio), the oil absorption level has little effect on the paint film; however, above CPVC, it can cause problems such as roughness and cracking of the paint film. 4. Impact on dispersion: Materials with high oil absorption generally require a larger amount of dispersants and wetting agents to facilitate color development and dispersion. 5. Particles of the same pigment powder in different aggregate states, subjected to different crushing methods and with varying moisture contents, will exhibit completely different oil absorption levels. 6. The control of oil absorption amount is only a reference value for testing, with a general deviation of 5%. One must conduct their own tests to confirm it. Finally, the oil absorption rate does not directly affect the properties of the coating; rather, it provides a parameter for formula development. The most important thing is to find CPVC on one’s own.