Most coatings are composed of raw materials such as base materials (one or more resin mixtures), pigments (including physical and functional pigments), solvents, and some small amounts of additives. In the production of coatings, after selecting various coating raw materials necessary for coating components, the next step is how to make reasonable use of the technical and economic performance of coating raw materials to produce high-quality coatings.
As is well known, the selection of various coating raw materials has a significant impact on the performance of coatings. Improper selection of a component may lead to the failure of the entire coating formula. Therefore, in the overall composition arrangement of paint formulations, in addition to fully considering the role of each component, compatibility and synergistic effects between various components should also be considered. After selecting the appropriate components, the volume concentration of the pigment must also be taken into account. In addition, the influence of solvents on the construction process and performance of coatings, as well as the role of solvents in controlling the fluidity, viscosity, and drying time of coatings, are all issues that must be considered in the correct selection of coating raw materials and overall raw material formula design.
Alkyd resin is a resin with a high dosage of Z in coating production, and its raw materials are easily available and the manufacturing process is simple. Alkyd resin contains a large number of ester groups, so the modification path is very wide. Polyamide modified alkyd resin can be used to produce thixotropic coatings, and amino resin can be used as an excellent coating raw material for coil materials and home appliance coatings.
Varnishes do not require a pigment ratio. But pigments must be added to the paint to increase color and coverage. Varnishes are colorless, transparent, and have no covering power, so paints with color and covering power account for a higher proportion of Z in paint varieties. Pigment is one of the important raw materials for paint Z.
Before adding pigments as raw materials for coatings, it is necessary to focus on color, covering power, and coloring power performance. Color refers to the color that the coating product needs to achieve. After being clearly defined in the overall planning of coating production, the correct selection of pigments should be made; The coverage of pigments is related to their refractive index, crystal type, and particle size. Among known pigments, rutile type TiO2 has a higher refractive index Z and a greater refractive index difference between it and the polymer, making it a white pigment with good hiding power Z. The hiding power of a pigment depends not only on the amount of light scattered by the coating, but also on its ability to absorb the light shining on it. Carbon black does not reflect light at all, but can absorb all the light that shines on it, so its coverage is strong. In addition, the particle size of pigments also has a direct impact on their hiding power;
The coloring power of pigments is a concept that is easily confused with the covering power of pigments. The similarity between coloring power and covering power is that both are the results of pigments absorbing and scattering light, with the difference being that covering power tends to scatter, while coloring power tends to absorb. It can be said that the stronger the absorption performance of pigments, the higher their coloring power. The greater the coloring power of pigments, the less they can be used. Therefore, the selection of coloring power of pigments is related to whether the production cost of coatings can be reduced.