Types and Selection of Paint Colorants

Types and selections of paint colorants

Traditional pigments are usually supplied in the form of fine powder. The advantages are strong versatility, good stability and convenient transportation. The disadvantage is that they cannot be used directly alone. They often need to add dispersants, wetting agents, etc. for strong mechanical grinding. There is a lot of dust during use, which pollutes the environment and makes color matching inconvenient.

Paint paste is a colorant used for color matching of paints and a pigment preparation. Powder pigments, solvents (water or organic solvents), resins, pigment dispersants and various functional stabilizers are processed through powerful mechanical compounding. They have good dispersion and stability, can flow, and have good compatibility with paints. wait.

Paint colorants are divided into water-based colorants, solvent-based colorants and water- and oil-based colorants. Water-based color paste is a pigment concentrate that uses water as the dispersion medium. It uses dispersants, wetting agents, stabilizers and other functional agents to fully wet and disperse the pigments, thereby optimizing the application performance of the pigments and stabilizing the system. Because water-based color pastes have good dispersion properties, they are more convenient to use than powdered pigments and will not cause dust pollution. Oil-based color pastes will release a large amount of toxic solvents, reducing environmental pollution. Using water-based color pastes as raw materials, i.e. color pastes, can It effectively solves the pollution of dust and sewage, is convenient to use and facilitates color matching, and can improve work efficiency and improve the application performance of pigments, such as improving color development and effectively preventing color floating and blooming. Therefore, it is widely used in various industries such as architectural coatings and toys.

Solvent-based color pastes use organic solvents and resins as dispersion media, and their color intensity and rheology are strictly controlled. It is composed of pigments, oily resins, pigment dispersants, stabilizers, co-solvents and functional additives. The key to choosing a solvent-based colorant is not only the compatibility between the colorant and the paint, but more importantly, the negative impact on the performance of the paint after adding the colorant, especially for high-end industrial paints. There are many differences between the solvents used in solvent-based colorants and water, such as volatility, flammability and explosiveness, and different solvents have different toxicity. They are dangerous goods. Therefore, the production, sales, and transportation of solvent-based colorants require corresponding regulations. Only qualifications are required.

Water-oil dual-purpose color paste refers to a pigment paste that can be used for both water-based paint coloring and paint (solvent-based paint) coloring. Technically, it is not only necessary to solve the compatibility and dispersion problems of the color paste with water-based coatings and solvent-based coatings, but also to solve the dilutability of the color paste in water and various other organic solvents. The development of this type of color paste is relatively difficult. Therefore, in principle, water-oil dual-purpose color paste refers to the pigment paste used for coloring some water-soluble paints and some weakly polar oil-based paints.

Before purchasing paint colorants, you should understand the relevant indicators and shelf life of paint colorants. Light resistance, weather resistance, color paste fineness, and storage stability are all methods for judging color paste quality. The color paste produced using first-class technology can still maintain very good fluidity without precipitation or delamination even after the warranty period. Some inferior products have become very thick and have no fluidity long before the product expires. The shelf life of such colorants is very short. In addition, different color paste products have different shelf lives. Due to the coating of fluorescent resin, the shelf life of fluorescent series colorants will be shorter than that of ordinary water-based colorants. The stability of some special color pastes will also be shortened due to technical difficulties. Before use, open the paint paste packaging barrel and carefully check whether there are any agglomerations or sedimentation at the bottom. When you see that the color paste is stratified and has no fluidity, you should contact the color paste manufacturer or distributor in time and do not use it casually to avoid losses.

Take interior and exterior wall coatings as an example. The exterior walls of buildings are exposed to the sun, rain, and strong exposure to ultraviolet light all year round. Some pigments will fade, turn yellow, and pulverize. When choosing colorants for exterior wall paints, be sure to choose paint colorants with better weather resistance and light resistance. Generally, phthalocyanine series and inorganic iron oxide color pastes are used for exterior wall paint colorants. Iron oxide colorants are darker in color and not bright enough, but they have good weather resistance and are very cheap.It is widely used in exterior wall coatings. Some organic pigment pastes with better performance can also be used in exterior wall coatings. The colors are bright and bright, and the weather resistance and light resistance can also meet the usage requirements. However, the prices of these color pastes are also relatively high. Water-based paints for interior walls are basically not affected by the outside climate. In terms of fastness performance, color pastes for interior wall paints are not as strict as color pastes for exterior wall paints, but the requirements for color safety and paint environmental protection are higher than those for exterior wall paints. many. The interior wall paint color paste should not only keep the color of the wall from fading or yellowing when living in the indoor environment, but also ensure the safety for human habitation. The color paste must be harmless, non-toxic, and zero VOC. When choosing a suitable water-based color paste, interior and exterior wall architectural coatings are simply as follows: Interior wall paint color pastes are more demanding in terms of color variety, high environmental protection and safety, and can meet individual needs; exterior wall coatings require weather resistance and durability. Well-done, cheap and affordable, partially meeting special performance requirements.