The Special Role Of ''water'' in Waterborne Coatings

Waterborne coating is a kind of coating with water as the main dispersible medium developed in the coating industry technology research and development with the development of social demand for environmental protection. Compared with our country traditional solvent type coating pollution problem serious defects, the basic functions of the "water" of water-based coating has established its position in the economic environment friendly coating.

In water-based coatings, water as a solvent and solvent coatings used in organic solvents have obvious differences: water resources are very rich, in terms of coating products, can be said to be endless, water is safe and harmless to human body, no pollution to the environment. The volatile substance of water is water vapor, which neither increases volatile organic compounds, nor produces harmful iodide air pollutants, nor produces atmospheric reactions under the action of light and oxygen, resulting in secondary air pollution. Water is not flammable, unlike solvent based paint is flammable, so whether it is transported paint, storage and construction have a greater safety risk. The water used in water-based paint is not tap water in the ordinary sense. This is specially treated deionized water. The basic requirements of deionized water are clean and free of mechanical impurities. Ordinary water contains calcium and magnesium plasma, which in electrophoretic paint can affect the stability of paint and tank paint (especially swimsuit deposition). Ordinary water also contains bacteria and microorganisms, which will affect the quality and stability of coating products. However, since deionized water requires professional equipment operation, there will be more production costs. But overall, deionized water is still much cheaper than organic solvents.

Water is a polar solvent. As the main components of latex paint, latex resins and fillers must be emulsified and dispersed in water with the help of emulsifiers and dispersants. At the same time, Texnol, propylene glycol phenyl ether, diethylene glycol butyl ether and triethylene glycol butyl ether can be used as film forming additives, because of the high surface tension of water, the evaporation rate is slow. To increase volatilization rate, it is usually necessary to add a small amount of organic solvent to reduce surface tension. For the above purposes, the addition of organic solvents will increase the toxicity of the product to human body and environmental pollution, and reduce the safety of the product. Therefore, the amount of organic solvents in waterborne coatings should be reduced as much as possible. This is also an important technical index to measure waterborne coatings.

In recent years, the research and development of water-based coatings have made great progress in the coating technology industry at home and abroad. The comprehensive analysis and evaluation of water-based coatings will be the most promising among the social environment friendly coatings in China.