For water-based coating systems, the problem of wetting is more likely to occur on certain substrates with low surface energy, while the surface tension of wood is low, mostly greater than 40mN/m.
By adding a small amount of substrate wetting agent, it is possible to reduce the surface tension of the coating and make the coating easy to apply. The effect of a substrate wetting agent depends on its ability to reduce the surface tension of the system at a very small amount, and at the same time, the application process does not have certain undesirable side effects (e.g., poor adhesion between coatings, easy blistering, increased water sensitivity of the system, etc.).
That is, the substrate wetting agent can effectively reduce the surface tension of the system, increase the wettability and permeability of the wood, but also promote the compatibility of defoamer and the system to improve interlayer adhesion.
The various tests are only for testing the dispersion effect and storage stability of the pigment, and are not the testing content of the full index of the coating. The development of science and technology and the improvement of people’s living standards have put forward new requirements for the development of coatings. The first is environmental protection. According to relevant reports, the amount of VOC (Volatile Organic Compounds) modified polypropylene wax emitted in the world today amounts to 20 million tons. Among them, 10 million tons comes from automobile exhaust, and paint is the second largest pollution source in modern society, and its VOC emissions are 3.5 million tons D1.
Therefore, how to reduce VOC emissions in the coatings industry has become a major issue that must be resolved. Paint manufacturers and formula developers are striving to develop and produce environmentally friendly paints in accordance with the requirements of the times. Water-based paints, powder paints, and high-solid paints are used to replace the original solvent-based paints to reduce and eliminate the impact of paint on the environment.
Secondly, in addition to the need to continue to strengthen the protective function of the coating, the requirements for the decorative function of the coating are also getting higher and higher, such as the flatness, gloss, abrasion resistance, scratch resistance and other properties of the coating film. Require. In order to meet these requirements, since the 1960s, the coating additive industry has developed at a rapid rate, and a wide variety of additives have been developed one after another. However, most of these additives are surface-active substances, which will produce “foam” problems, so defoamers must be used to solve them.
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