At present, the main types of anti-corrosion coatings for steel pipes are:
1. Grease paint
Grease paint is a type of paint with drying oil as the main film-forming material. Its characteristics are easy to produce, good paintability, good wettability to the surface, low price, and flexible paint film; but the paint film dries slowly, the film is soft, the mechanical properties are poor, acid and alkali resistance, water resistance and resistance Poor organic solvent properties. Dry oil is often combined with anti-rust pigments to form anti-rust paint, which is used in atmospheric environments where corrosion resistance is not high.
2. National paint
National lacquer is also called raw lacquer and large lacquer, which is unique to our country. Raw lacquer is a milky-white viscous liquid that flows out of the bark of the sumac tree and is filtered to remove impurities. After the raw lacquer is applied to the surface of the object, the color quickly changes from white to red and from red to purple. After a long time, it can become a hard and bright black paint film. Urushiol is the main component of raw lacquer, with a content of 30-70% (the higher the urushiol content, the better the quality of raw lacquer). National paint has strong adhesion, tough paint film and good gloss. It is resistant to soil corrosion, water and oil. The disadvantage is that it is toxic and easy to cause skin allergies. In addition, it is not resistant to strong oxidants and has poor alkali resistance.
3. Phenolic resin coating
There are mainly alcohol-soluble phenolic resins, modified phenolic resins, and pure phenolic resins. Alcohol-soluble phenolic resin coatings have better corrosion resistance, but its disadvantages are inconvenient construction, poor flexibility, and weak adhesion, so the application is subject to certain restrictions. The phenolic resin needs to be modified during use. For example, rosin-modified phenolic resin is refined with tung oil, and various pigments are added. After grinding, various enamels can be made. The paint film is tough and low in price. It is widely used in the coating of furniture, doors and windows. Pure phenolic resin coating has strong adhesion, water resistance, humidity and heat resistance, corrosion resistance and good weather resistance.
