1, grease coating
Grease coating is a kind of coating with drying oil as the main film-forming substance. It is characterized by easy production, good paintability, good wettability to objects, low price and flexible paint film. However, the paint film is slow to dry and soft, and its mechanical properties, acid and alkali resistance, water resistance and organic solvent resistance are poor. Drying oil is often combined with antirust pigments to form antirust paint, which is used in atmospheric environment with low corrosion resistance requirements.
2. Raw lacquer
Raw lacquer is a milky viscous liquid, which flows from the growing bark of Rhus verniciflua. After it is coated on the surface of an object, the color quickly changes from white to red and from red to purple, and it can become a hard and bright black paint film over time. Urushiol is the main component of raw lacquer, with a content of 30% ~ 70%. Generally speaking, the higher the urushiol content, the better the quality of raw lacquer. Raw lacquer has strong adhesion, tough paint film and good luster. It is resistant to soil corrosion, water and oil. The disadvantage is that it is toxic and easy to make people allergic to skin. In addition, it is not resistant to strong oxidants and has poor alkali resistance.
3. Phenolic resin coating
There are mainly alcohol-soluble phenolic resin, modified phenolic resin and pure phenolic resin. Alcohol-soluble phenolic resin coating has good anticorrosion performance, but its application is limited due to inconvenient construction, poor flexibility and adhesion. Therefore, it is often necessary to modify phenolic resin. For example, rosin modified phenolic resin and tung oil are refined, and various pigments are added and ground to make various enamels. The paint film is tough and cheap, and is widely used for painting furniture, doors and windows. Pure phenolic resin coating has strong adhesion, water resistance, wet and hot resistance, corrosion resistance and good weather resistance.
4. Epoxy resin coating
Epoxy coating has good adhesion to metal, concrete, wood, glass, etc. Alkali resistance, oil resistance, water resistance and good electrical insulation. But the aging resistance is poor. Epoxy anticorrosive coatings are usually composed of epoxy resin and curing agent. The properties of curing agent also affect the properties of paint film.
5. Polyurethane coating
Polyurethane resin used for anticorrosive coatings usually contains two components: isocyanate group -NCO and hydroxyl group. When in use, the two components are mixed, reacted and cured to generate polyurethane. Polyurethane coatings have good physical and mechanical properties, and the paint film is hard, flexible, bright, plump, wear-resistant and has strong adhesion. Excellent corrosion resistance and aging resistance are better than epoxy coatings, which are often used as topcoat and primer.
6. vinyl resin coating
Vinyl resin anticorrosive coatings mainly refer to coatings with vinyl chloride, vinyl acetate, ethylene, propylene and other monomers as film-forming substances. Among them, perchloroethylene coatings have been produced and applied in large quantities. Perchloroethylene paint can form a dense paint film with good chemical corrosion resistance, but its stability to light and heat is poor, so it should not exceed 60℃ for long-term use and its adhesion to metals is poor. The coating is rich in raw materials and has been widely used to prevent chemical atmospheric corrosion.
7. Furan resin coating
Furan resin coating is resistant to various non-oxidizing inorganic acids, electrolyte solutions and various organic solvents, and its alkali resistance is also outstanding, but its oxidation resistance is not good. Furan resin series anticorrosive coatings include furfuryl alcohol resin coatings, furfural acetone formaldehyde resin coatings and modified furan resin coatings.
8. Rubber coating
Rubber anticorrosive coating is made of natural rubber or synthetic rubber after chemical treatment or mechanical processing as film-forming substance, and solvent, filler, pigment and catalyst are added.
9, asphalt coating
Asphalt is one of the important anticorrosive coatings. Especially coal tar pitch is the best. Coal tar pitch coating has the advantages of low price, water resistance, corrosion resistance to some chemical media, good wettability and high solid content on the surface of steel that has not been completely derusted.
Its disadvantage is crisp in winter and soft in summer. After exposure, some components will volatilize and escape, causing the paint film to crack. These shortcomings can be improved by adding some other resins.
10, heavy-duty anticorrosive coating
Heavy-duty anticorrosive coatings are relative to general anticorrosive coatings. Refers to the anti-corrosion coating with several times higher anti-corrosion effect than the general anti-corrosion coating under severe corrosion conditions. It is characterized by excellent resistance to strong corrosive media, outstanding durability and service life of more than several years. Mainly used in marine structures and chemical equipment, storage tanks and pipelines.
What are the characteristics of anticorrosive coatings?
1, which can be used in harsh conditions and has a long corrosion-resistant life. In chemical atmosphere and marine environment, heavy-duty anticorrosive coatings can generally be used for more than 18 years or 15 years, even in acid, alkali, salt and solvent media, at a certain temperature, they can be used for more than 5 years.
2. Thick film is an important symbol of heavy anti-corrosion coating. The dry film thickness of general anticorrosive coatings is about 100μm or 150μm, while the dry film thickness of heavy-duty anticorrosive coatings is above 200μm or 300μm, with 500μ m ~1000μ m.. ..
3. Strong adhesion: the coating has strong adhesion to the substrate, and the coating composition contains hydroxyl (-OH). The metal matrix provides positive ions, which can form chemical bonds, and even realize the combination of valence chains with the help of coupling agents in the coating. Supported by the spatial network structure, the metal, metal oxide nano-materials and rare earth oxide ultrafine powder contained in the coating composition help the coating to form a dense interface transition layer, so that its comprehensive thermodynamic properties match the matrix.
4. Efficient and convenient: the construction is simple, and the self-curing of inorganic coatings at room temperature is truly realized. When the ambient temperature is 20℃ and the relative humidity is less than 85%, the surface drying time is 15min, and it can work for 2 hours, which can not only ensure efficient construction, but also achieve excellent salt spray resistance and aging resistance. The coating has self-repairing renaturation, local scratches caused by external force can still be protected, the coating is not damaged by cutting and welding, and the welding with coating does not affect the welding quality.
5. Flexible construction method: inorganic polymer anticorrosive coatings can be used alone or as bottom anticorrosive coatings and organic coatings, and single-layer inorganic polymer anticorrosive coatings can be used with epoxy system, acrylic system and polyurethane system. As an introduction.