What are Protective Coatings?
Paint printing is also known as pigment printing. It uses mixed water-insoluble colored substances (that is, pigments) and high-molecular polymers (called: adhesives) to print on textiles. After a certain treatment, they are formed on textiles. Beautiful, will not fade, convenient and fast.
Coating protection
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- Paint printing is also known as pigment printing. It uses mixed water-insoluble colored substances (that is, pigments) and high-molecular polymers (called: adhesives) to print on textiles. After a certain treatment, they are formed on textiles. Beautiful, will not fade, convenient and fast.
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- Coatings are generally considered to protect metals based on the following three aspects.
- 1. Shielding effect. After coating the metal surface, the metal surface is relatively separated from the environment. This protective effect can be called shielding effect. But it must be pointed out that a thin layer of paint cannot provide absolute shielding. Because polymers have some air permeability, water and oxygen molecules are usually only a few angstroms in diameter. So when the coating is thin, they can pass freely.
- 2. Inhibition effect. The internal components of the coating react with the metal to passivate the metal surface or form a protective substance to improve the protective effect of the coating. In addition, the degradation products produced by some oils under the drying action of metal soaps can also act as organic corrosion inhibitors.
- 3. Electrochemical protection. Dielectric penetrating coatings will form electrochemical corrosion under the film when they contact the metal surface. In the coating, a metal with a higher activity than iron is used as a filler, such as zinc. It will protect the sacrificial anode, and the corrosion products of zinc are salt-based zinc chloride and zinc carbonate, which will fill the gaps of the film, make the film compact, and greatly reduce the corrosion.
- When discussing the reasons for the damage of coatings, it is easy to think that the damage of coatings is caused by the corrosive effect of environmental media on the coatings. In fact, this kind of situation rarely occurs, especially at present, many synthetic resins have relatively excellent corrosion resistance. As long as the coating is properly screened according to the corrosion conditions, such damage will not occur. The majority of coating damage is caused by defects in the coating. Because the localized corrosion of the metal will occur in the defect area, and the localized corrosion of the metal often causes the coating to bulge, peel, and crack.
- Although there are many types of coatings, as far as their composition is concerned, they can be divided into three parts, that is, the main film-forming substance, the secondary film-forming substance, and the auxiliary film-forming substance.
- Oils and resins are the main film-forming substances, called fixing agents, that is, adhesives, which are the basis of paints. Without them, it is impossible to generate a paint film firmly attached to the surface of the material; color is a secondary film-forming substance. Although he It cannot be a paint alone, but it can give a certain color and hiding power to the paint film, increase the thickness of the layer, and improve the wear resistance, heat resistance and corrosion resistance of the paint film; solvents, thinners and other auxiliary materials are auxiliary film-forming substances It helps to cover the coating and improve the film performance.