Although there are many types of coatings, they can be roughly divided into three parts in terms of their composition: main film-forming substances, secondary film-forming substances, and auxiliary film-forming substances.
1. Main film-forming substances
① Oil. Oilseeds are natural products derived from plant seeds and animal fats. The drying and solidification reaction of oil mainly involves the polymerization of oxygen in the air and unsaturated double bonds in the oil. The various properties of natural oils, especially their corrosion resistance and aging resistance, are not as good as many synthetic resins. They are rarely used as anti-corrosion coatings alone, but they can be combined with some metal oxides or metal saponifications to prevent rust on metals. Therefore, oils can be used to modify various synthetic resins to produce matching anti rust primers.
② Natural resins and synthetic resins. Natural resin refers to asphalt, raw paint, natural rubber, etc. Synthetic resins refer to epoxy resins, phenolic resins, furan resins, polyester resins, polyurethane resins, ethylene resins, vinyl chloride resins, and fluorine-containing resins, which are the main film-forming substances in commonly used corrosion-resistant coatings.
2. Secondary film-forming substance (pigment)
Pigments are one of the main components of coatings. Adding pigments to coatings not only makes them decorative, but more importantly, improves their physical and chemical properties, enhances their mechanical strength, adhesion, impermeability, and corrosion resistance. It also filters out harmful light waves, thereby enhancing the weather resistance and protection of coatings. Mainly divided into rust proof pigments, body pigments, and coloring pigments:
① Rust proof pigment. According to different anti rust mechanisms, chemical anti rust pigments can be classified, such as red lead, zinc chromium yellow, zinc powder, zinc phosphate, and organic chromate. These pigments act as anti rust agents in coatings through chemical or electrochemical means; Another type is physical anti rust pigments, such as aluminum powder, mica iron oxide, zinc oxide, and graphite powder. Their main function is to increase the density of the paint film, reduce the permeability of the paint film, prevent sunlight and moisture from penetrating, and enhance the anti rust effect of the coating.
② Physical pigments. Constitutional pigments can improve the weather resistance, impermeability, wear resistance, and physical and mechanical strength of coatings. Commonly used pigments include talcum powder, calcium carbonate, barium sulfate, mica powder, and diatomaceous earth.
③ Coloring pigments. Coloring pigments mainly play a role in coloring and covering the film surface in coatings.
3. Auxiliary film-forming substance
① Solvent. It mainly plays a role in dissolving film-forming substances, adjusting coating viscosity, and controlling coating drying speed in coatings. The solvent has an impact on some characteristics of the coating, such as brushing resistance, leveling, film-forming speed, flowability, dryness, cohesiveness, wettability, and low-temperature usability.
② Other auxiliary materials.
Plasticizer: Used to improve the flexibility, impact resistance, and overcome the disadvantages of hard brittleness and easy cracking of paint films.
Thixotropic agent: It reduces the viscosity of the coating during the brushing process, making it easier to apply.
Surfactants, mold inhibitors, UV absorbers, and stain removers, etc.
The types of coatings are divided into three parts: the first part is the film-forming substance; The second part is the basic name, represented by two digits; The third part is the numbering. Example: H 50-2: Epoxy resin acid resistant paint.