The use of dispersants in white slurry

The main component of the white paste used in white coatings and inks is titanium dioxide. Titanium dioxide is a very important raw material in industrial production, widely used in industries such as coatings, plastics, papermaking, printing inks, chemical fibers, rubber, cosmetics, ceramics, enamel, electronics, food, and medicine. Among them, coatings account for the largest proportion, about 60%.

Titanium dioxide is the strongest coloring agent among white pigments, with excellent coverage and color fastness, suitable for opaque white products; It is a soft, odorless and tasteless white powder with strong covering and coloring power, with a melting point of 1560-1580 ℃. Insoluble in water, dilute inorganic acids, organic solvents, and oil, slightly soluble in alkali, soluble in concentrated sulfuric acid. It turns yellow when heated and white again when cooled. In our paint production process, pigment dispersion is a very important production link, which directly affects the storage, application, appearance, and performance of the paint film. Therefore, selecting dispersants reasonably is a very important link.

The main function of dispersants is to reduce the time and energy required to complete the dispersion process, stabilize the dispersed pigment dispersion, modify the surface properties of pigment particles, and adjust the mobility of pigment particles; Specifically reflected in the following aspects: shortening the dispersion time. Improve gloss. Improve coloring and covering power. Improve color display and color matching. Prevent floating colors and discoloration. Prevent flocculation. Prevent settlement. Generally, engineers or experimenters receive a dispersant and start testing its compatibility. If it is compatible, they will use their own experience formula to grind and disperse the white slurry. For the formulation of spray paint grinding, a horizontal sand mill is generally selected for production, while a disperser is used for high-speed dispersion in the laboratory; Most of the current titanium dioxide can be directly dispersed at high speed to reduce its fineness. Printing ink usually uses a basket type sand mill, but screen printing ink generally requires a particularly fine fineness, good fluidity, and high viscosity. At this time, a three roll machine is selected for grinding, and the resulting white paste is delicate, glossy, and has good fluidity. If the white slurry is not well dispersed, it will cause the particles to become coarse. Insufficient grinding fineness. After painting, there may be fogging, blooming, coagulation, or floating colors during the spraying process. The reason for this may be: insufficient dispersion speed. The wetting property of the dispersant is insufficient. Insufficient or completely unsuitable dosage of dispersant. If the dispersion speed is not enough, increase the speed; Insufficient wetting and insufficient dispersant dosage may indicate that the dispersant dosage of this color paste exceeds the lower limit of the empirical formula. The dosage can be increased, but cost considerations must also be taken into account. The manufacturer recommends a dispersant dosage of 5% -10% of the inorganic pigment, but engineers usually design the formula based on the minimum amount. There are so many manufacturers of dispersants on the market, so you can choose dispersants with low dosage that achieve the purpose of dispersion. After comprehensive consideration, choose a dispersant that can disperse the fineness to the desired fineness, and then conduct performance testing.