Waterborne coatings are all coatings with water as solvent or dispersion medium, which can be called waterborne coatings.
Oily paint is a kind of paint with drying oil as the main film-forming substance.
2. Different characteristics
The pigment dispersion of waterborne coatings is poor.
The pigment of oily paint has strong dispersibility and good ductility.
Extended data:
1, protection function
Anti-corrosion, waterproof, oil-proof, chemical-resistant, light-resistant and temperature-resistant. Exposed to the atmosphere, objects will be eroded by oxygen and moisture, leading to metal corrosion, wood decay and cement weathering. Coating oily paint on the surface of objects to form a protective film can prevent or delay the occurrence and development of these damage phenomena and prolong the service life of various materials. Therefore, protection is a main function of oily coatings.
2, decorative function
Color, luster, pattern and smoothness. Oily paint can be coated on objects made of different materials to get colorful appearance, which plays a role in beautifying the living environment of human beings and makes a contribution to human material life and spiritual life.
3. Other functions
Marking, antifouling, insulation, etc. For modern oily coatings, this effect is more and more important than the first two effects. Some modern oily coatings can provide a variety of special functions, such as electrical insulation, conductivity, electromagnetic wave shielding, anti-static generation and so on.
Biochemical function of E69DA5E887AAE79FA5E98193313334331366261; High temperature resistance, heat preservation, temperature indication and temperature marking, prevention of delayed combustion, ablation and heat insulation; Reflecting light, emitting light, absorbing and reflecting infrared rays, absorbing solar energy, shielding rays, marking colors and other optical properties.
Anti-skid, self-lubrication, anti-chipping, anti-splash and other mechanical properties; It also has many functions, such as noise prevention, vibration reduction, sanitation and disinfection, condensation prevention and icing prevention. With the development of national economy and the progress of science and technology, oily coatings will provide and play various new special functions in more aspects.
1, the pigment dispersion of waterborne coatings is poor.
2, the surface tension is large.
3. The latent heat of evaporation is large, that is, it is greatly influenced by temperature and humidity.
4. Poor dispersion stability and poor shear resistance; Good electrical conductivity and high corrosiveness.
Disadvantages 1: Waterborne coatings have high requirements on the cleanliness of construction process and material surface. Due to the large surface tension of water, dirt is easy to shrink the coating.
Disadvantage 2: Waterborne coatings have poor dispersion stability to strong mechanical force. When the flow velocity in the conveying pipeline changes sharply, the dispersed particles are compressed into solid particles, which makes the coating film pockmarked. It is required that the conveying pipeline has a good shape and the pipe wall is free of defects.
Disadvantage 3: Water-based coatings are corrosive to painting equipment, so it is necessary to use anti-corrosion lining or stainless steel materials, and the equipment cost is high. Waterborne coatings corrode pipelines, dissolve metals, precipitate dispersed particles, and produce pits on the coatings. Stainless steel tubes are also needed.
Disadvantage 4: Baking water-based coatings requires strict construction environment conditions (temperature and humidity), which increases the investment and energy consumption of temperature and humidity control equipment.
Disadvantage 5: Water-based coatings have high latent heat of evaporation and high baking energy consumption. Cathodic electrophoretic coating should be baked at 65438 080℃; But it takes a long time for latex paint to dry completely.
Disadvantage 6: The organic cosolvent with high boiling point of waterborne coatings will produce a lot of oil fume during baking, which will drop on the surface of the coating film after condensation, affecting the appearance.
Disadvantage 7: The poor water resistance of waterborne coatings makes the stability of coatings and bath solution poor, and the water resistance of coatings is poor. The medium of waterborne coatings is generally weakly alkaline (pH 7.5 ~ pH 8.5), and the ester bond in the resin is easy to hydrolyze and degrade the molecular chain, which affects the stability of coatings and baths and the performance of coatings.
Although there are many problems in waterborne coatings, some problems have been prevented through the continuous improvement of formula, coating technology and equipment, and some problems have been improved and improved through the formula itself.
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