With the rising tide of waterborne nano-coating applications, people have also accelerated the research on the application of nano-powders in water-based coatings. At the beginning, the conventional preparation technology of directly using nano-powder as an additive for coatings and then using mechanical methods for dispersion is generally adopted. .
However, although some properties of waterborne coatings can be improved by the addition of nanopowders, conventional mechanical dispersion methods do not ensure that nanopowders are effectively dispersed in the aqueous nanopowments they produce, and are less able to inhibit the dispersion of dispersed nanoparticles. Secondary self-aggregation phenomenon. Because in the aqueous medium, the high surface energy and specific surface area of ​​the nano-powder can strongly adsorb the aqueous medium, and the reaction forms an R-OH-based structure, so that the interaction force between the powder and the surface activity of the powder are enhanced. Moreover, the R-OH group is prone to polymerization or a new linker, which makes it easy to agglomerate the nanopowder and is difficult to disperse, and the commonly used modifiers such as fatty alcohols, amines, fatty acids, and siloxanes are not suitable. Used in aqueous media. Therefore, how to select appropriate surfactants to make nano-powders disperse more effectively in water-based coating media has become an important issue for people.
Nano-powders need to be well-dispersed if they are well dispersed in aqueous coating media and have long-term stability and do not undergo secondary self-aggregation during long-term storage. Domestic and foreign scholars have done a lot of research on nano powder modification. They found that adding dispersant and surface encapsulant can modify and modify the surface of nano powder.
In the process of conventional coating preparation, the nano-powder precursor, the reaction control agent and the diluent water are added, and the corresponding nano-powder can be directly synthesized on the surface of the pigment-filled particles to prepare a significant nano-modification effect. High performance nano coatings.
In addition, in order to improve the dispersibility of the nanopowder in the aqueous coating, it is also possible to replace the dispersion medium, such as an aqueous emulsion, an acrylic emulsion, or the like, instead of a general aqueous medium.
The aqueous emulsion has better film-forming properties than the general aqueous medium. The aqueous emulsion as the dispersion medium of the nano-powder can not only obtain a coating with good performance, but also the dispersion and long-term stability of the coating can be ensured.
The acrylic emulsion has good dispersibility for ordinary powders, so it can be used as a dispersion medium for nano-powders in aqueous coatings.
As a global environmentally friendly coating, waterborne nano-coating has attracted the attention of all countries in the world. With the increasing demand for clean and environmentally friendly industries in the world, the development of water-based environmentally-friendly nano-coatings will pose a challenge to the research of traditional solvent-based nano-coatings, and will also provide high-performance, environmentally-friendly and functional nano-coatings. New methods and opportunities.
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