Selection of pigments and resins for coatings
Most coatings are composed of a base material (one or more resin mixtures), pigments (including physical pigments and functional pigments), solvents and some small amounts of additives and other coating raw materials.
In the production of coatings, after the selection of various coating raw materials necessary for coating components, the next is how to make reasonable use of the technical and economic properties of coating raw materials to produce high-quality coatings.
As we all know, the selection of various coating raw materials has a great impact on the performance of the coating. If one component is not selected properly, the entire paint formulation may fail.
Therefore, in the overall composition arrangement of the coating formula, in addition to fully considering the role of each component, there is also consideration of compatibility and synergy between various components. After selecting the appropriate component, the volume concentration of the pigment must also be taken into account. In addition, the influence of the solvent on the construction process of the coating and the coating performance, as well as the role of the solvent on the control of the fluidity, viscosity, and drying time of the coating are all issues that must be considered in the correct selection of the coating raw materials and the overall raw material formulation design. Alkyd resin is the most used resin in coating production, its raw materials are easy to obtain and the manufacturing process is simple. Alkyd resin contains a large number of ester groups, so the way of modification is very wide. Thixotropic coatings can be prepared with polyamide modified alkyd resin, and amino resin can be used as excellent coating materials for coil and home appliance coatings. Varnish requires no pigment ratio. But color paint must be added to increase color and coverage. The varnish is colorless and transparent, and has no covering power, so the color paint with color and covering power accounts for the highest proportion of paint varieties. Pigment is one of the most important paint raw materials.
Before the use of paint pigments, it is necessary to focus on the color, hiding power and coloring power performance. Color is the color that the coating product needs to achieve, which is correctly selected when selecting pigments after it is clearly defined in the overall plan of coating production; The covering power of pigment is related to its refractive index, crystal type and particle size.
Among the known pigments, rutile TiO2 has the largest refractive index and the largest refractive index difference between it and the polymer, so it is the white pigment with the best hiding power.
The hiding power of the pigment depends not only on the amount of light scattered by the paint, but also on the absorption capacity of the light irradiated on it. For example, carbon black does not reflect light at all, but can absorb all the light irradiated on it, so its hiding power is the strongest. In addition, the particle size of the pigment also has a direct effect on the hiding power;
The coloring power of pigments is the concept that is most easily confused with the hiding power of pigments. Coloring power and covering power are similar to the result of pigment absorption and scattering of light, the difference is that the covering power is biased to scattering, coloring power is biased to absorption. It can be said that the stronger the absorption performance of the pigment, the higher its coloring power. The greater the coloring power of the pigment, the less it can be used, so the choice of the coloring power of the pigment is related to whether the production cost of the paint can be reduced.
Sinograce Chemical production of various water based coating resin, welcome to consult.
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