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The special role of water in water-based coatings

Jun 03, 2020

     Waterborne paint is a kind of paint that uses water as the main dispersion medium and developed in the paint industry with the emergence of environmental protection requirements. Compared with the serious pollution defects of traditional solvent-based coatings, the basic characteristics of "water" of water-based coatings have established its position in environmentally friendly coatings.

    In water-based coatings, water as a solvent has significantly different properties compared to organic solvents used in solvent-based coatings: water resources are very rich, as far as coating products are concerned, it can be said to be inexhaustible; water is safe and harmless to humans , No pollution to the environment. The volatile matter of water is water vapor, which will neither increase VOC nor produce harmful iad air pollutants, nor will it cause atmospheric reaction under the action of light and oxygen, causing secondary air pollution; water is incombustible, Unlike solvent-based paints, they are flammable, so there is a big hidden danger in paint transportation, storage and construction. The water used in water-based coatings is not tap water in the general sense. It is deionized water obtained after special treatment. The basic requirements of deionized water are clean and free of mechanical impurities. The calcium and magnesium ions contained in ordinary water will affect the stability of the paint solution and the tank paint in the electrophoretic paint (especially the deposited swimwear). Ordinary water also contains bacterial microorganisms, which will affect the quality and stability of coating products. However, since deionized water requires specialized equipment to operate, it will incur more production costs. But overall, deionized water is still much cheaper than organic solvents.

    Water is a polar solvent. Emulsion resins and pigments used as the main components of paints in latex paints must be emulsified and dispersed in water with the aid of emulsifiers and dispersants. Ether and triethylene glycol butyl ether are used as film-forming additives. Due to the large surface tension of water and the slow volatilization rate, it is often necessary to add a small amount of organic solvent to reduce the surface tension to increase the volatilization rate. For the above purpose, when organic solvents are added, the product's toxicity to the human body and environmental pollution are correspondingly increased, and the safety of the product is reduced. Therefore, the amount of organic solvents should be minimized in water-based coatings. This is also an important technical indicator for measuring water-based coatings.

    In recent years, the domestic and foreign coatings industry has made considerable progress in the research and development of water-based coatings. Comprehensive evaluation of water-based coatings will be the most promising type of environmentally friendly coatings.