In terms of composition and environmental protection: the main variety of water-based architectural coatings is latex paint. Latex paint is mainly composed of water, emulsion, pigments and fillers and various additives. The composition of solvent-based coatings is composed of resin, pigments and fillers, solvents and various additives.
It can be seen from this that the dispersion medium of water-based coatings is water. After the coating is applied, water and a small amount of additives are volatilized from the coating film, which has environmental protection and safety properties; while the dispersion medium of solvent-based coatings is organic solvent (generally referred to as VOC), the organic solvents volatilized from the coating film are mostly toxic and harmful substances, which not only cause harm to the human body, but also cause pollution to the natural environment.
From the physical and chemical properties of the coating film: some physical and chemical properties of water-based coatings are inferior to solvent-based coatings, such as chemical resistance, weather resistance, stain resistance, etc. Therefore, the service life of water-based coatings is not as long as that of solvent-based coatings. But water-based coatings also have some high-grade products: such as water-based silicone-acrylic coatings, fluorocarbon coatings, etc., the service life can also reach about 10 to 15 years.
In terms of construction environment: slip antiblock additives water based coating, the construction of water-based coatings generally requires construction above 5 °C, and solvent-based coatings can also be constructed at 0 °C. Therefore, in northern regions, solvent-based coatings can be used for construction near winter.
From the requirements of the base layer: the moisture content of the base layer in the construction of water-based paint should be less than 10%, and the moisture content of the base layer in the construction of solvent-based paint should be less than 8%. The air permeability of water-based coatings is relatively good, and the water vapor inside the base layer can diffuse outward; while solvent-based coatings form a dense film, if the moisture content of the base layer is high, the water vapor cannot evaporate from the coating film, and it is easy to foam.
What are the main functions and characteristics of exterior wall coatings?
The main function of exterior wall paint is to decorate and protect the exterior walls of buildings, so that the appearance of buildings is clean and beautiful, so as to achieve the purpose of beautifying the urban environment. At the same time, it can protect the outer wall of the building and prolong its use time. In order to obtain the ideal decoration and protection effect, the exterior wall coating should have the following characteristics.
(1) Good decoration
It is required that the exterior wall paint is rich in color and excellent in color retention, and can maintain the original decorative performance for a long time.
(2) Good weather resistance
Exterior wall coatings are mainly used outdoors. The coatings are exposed to the atmosphere and are subject to the effects of sunlight, rain, sandstorms, and changes in cold and heat. Under these external effects, the coatings are prone to cracking, chalking, peeling, and discoloration. so that the coating loses its original decorative and protective functions. Therefore, as an exterior wall coating, its coating requires that the above-mentioned damage does not occur within a specified period of time, that is, good weather resistance.
(3) Good stain resistance
Due to the poor environmental conditions in our country, generally speaking, the environmental pollution is more serious, and there are more dust and other suspended substances in the atmosphere, which are easy to contaminate the coating, and the coating will lose its decorative effect and become unrecognizable. affect the appearance of the building. Therefore, it is required that the exterior wall decorative coating is not easily stained by these substances, or is easily removed after being stained.
(4) Good water resistance
Exterior wall coatings are often washed by rainwater when exposed to the atmosphere, so exterior wall coatings should have good water resistance, and some elastic exterior wall coatings require better waterproof performance. When micro cracks occur on the base wall, the coating film remains intact and has waterproof function.
(5) Good mildew resistance
Exterior paint finishes are prone to mold growth in humid environments. Therefore, the coating film is required to inhibit the growth of mold and algae.
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