Acid dyes, direct dyes and reactive dyes are all water-soluble dyes, and the output in 2001 was 30,000 tons, 20,000 tons and 45,000 tons respectively. However, for a long time, my country's dye enterprises have paid more attention to the development and research of new structural dyes, while the research on the post-processing of dyes is relatively weak. Standardizing reagents commonly used for water-soluble dyes include sodium sulfate (yuanming powder), dextrin, starch derivatives, sucrose, urea, naphthalene formaldehyde sulfonate, etc. These standardizing reagents are mixed with the original dyes in proportion to obtain the required strength. Commodities, but they cannot meet the needs of different printing and dyeing processes in the printing and dyeing industry. Although the cost of the above-mentioned dye thinners is relatively low, the wettability and water solubility are relatively poor, so it is difficult to meet the needs of the international market, and can only be exported as original dyes. Therefore, in the commercialization of water-soluble dyes, the wettability and water-solubility of the dyes are urgent problems, and corresponding auxiliaries must be relied on.
Wetting in a broad sense is the replacement of one fluid (should be a gas) on a surface by another. Specifically, the powder or granular interface should be a gas/solid interface, and the process of wetting occurs when the liquid (water) replaces the gas on the particle surface. It can be seen that wetting is a surface physical process between substances. In the post-processing of dyes, wetting often plays an important role. Generally, dyes are processed into solid forms, such as powder or granules, which need to be wetted when used. Therefore, the wettability of the dye will directly affect the application effect. For example, during the dissolution process, it is undesirable for the dye to be difficult to wet and float on the water surface. With the continuous improvement of the quality requirements of dyes today, wetting performance has been used as one of the indicators to measure the quality of dyes. The surface energy of water is 72.75mN/m at 20°C, which decreases with the increase of temperature, while the surface energy of solid is basically unchanged, generally below 100mN/m. Usually metals and their oxides, inorganic salts, etc. are easy to wet. wet, known as high surface energy. The surface energy of solid organics and polymers is comparable to the surface energy of general liquids, which is called low surface energy, but it varies with the particle size of the solid and the degree of porosity. The higher the energy, its size depends on the substrate. Therefore, the particle size of the dye must be small. After the dye is commercialized by different media such as salting out and grinding, the particle size of the dye becomes finer, the crystallinity decreases, and the crystal phase changes, which improves the surface energy of the dye and facilitates wetting.