Application Status and Development of Waterborne Coatings

Waterborne coatings not only have the advantage of low VOC emissions, but also have comparable coating performance to solvent-based coatings, and are undoubtedly the “big brothers” of future coatings industry development.

Waterborne Coatings Status
At present, the development speed of water-based paints is fast, and the average utilization rate of foreign water-based environmental protection paints has reached 80%, while in China it is relatively low at only 25% (but it is growing at a rate of around 7% per year). In several large application areas of the paint industry, water-based paints occupy a considerable proportion of both buildings and automobiles. For example, in the field of architectural coatings, water-based paints have an absolute advantage in industrial developed countries. Almost all water-based paints are applied on the outer walls of Western Europe, and up to 70-90% of the United States, Japan, and other countries, and Singapore's residential building exterior paints are used. The rate is as high as 85%; in the automotive sector, waterborne coatings are not only widely used in the automotive industry, but are also being developed at an unprecedented rate in the automotive repair industry. All industrial countries in the world have attached great importance to the development of water-based coatings. For example, the development of water-based coatings in the United States accounts for more than 50% of all coating development, while the development of water-based coatings accounts for 20% of the total coating results; In the first century, we began to attach importance to and proceed with the development of low-environment-type paints based on waterborne coatings. In recent years, China has also issued many important environmental protection regulations and implementation standards for the research, development and production of water-based coatings.

Waterborne coating application
In recent years, the development and progress of raw materials for waterborne coatings and manufacturing technology have accelerated the pace of growth of waterborne coatings. The largest amount of water-based paint is architectural paint, accounting for more than half, followed by automobiles, equipment, corrosion, wood products, etc., will be introduced one by one.

Water-based architectural coatings: From the perspective of development, interior wall coatings should develop towards healthy, gradually achieving zero VOC and as little residual monomers as possible; the development direction of exterior coatings is high stain resistance, self-emulsification, high solids Points and low VOC latex paint. The water-based interior wall coating has been basically completed. Each year, major coating companies are constantly introducing a number of better-performing interior wall water-based coatings (especially latex paints): Europe's Goodyear Chemicals uses surfactant-free carboxylated styrene Emulsion made of paint; US PPG's Pit/sburghPaints subsidiary successfully developed a series of zero-VOC interior paints with properties comparable to traditional high-quality paints (including durability, hiding power, repairability, etc.) in painting and Very slight odor and mildew during drying; British ICI Company recently launched two new high-end eco-friendly paint products “Dulux 2nd Generation 5 in 1 Wall Paint” and “Ultra-easy Wall Paint” in the Chinese market. , These two new products have the characteristics of super easy to scrub, mold and alkali, paint film is smooth, lasting bright, fresh smell, easy to construction and other characteristics; Japan Kansai paint company has also developed successfully without VOC and with formaldehyde removal function of water The paint, which can be used for interior decoration of interior buildings, the company also introduced a paint for improving the interior environment, which is specially designed to solve the problem of interior decoration of new building materials, furniture and wallpapers. (e.g. polyvinyl chloride cloth), etc., caused by trace amounts of chemical substances caused by the problem of patients in the residential condition group.

In the exterior decoration, the usage rate of waterborne coatings in Japan and Europe and the United States is as high as 90%. In China, mosaics, tiles, etc. are still widely used. The usage rate of paint is only 10%. We know that in buildings, especially high-rise buildings. In the facade decoration, the use of materials such as mosaics and tiles will not only increase the bearing weight of the building, but also be sticky, and it is easy to fall. It is not safe and beautiful, and there are certain difficulties in the construction. If paint is used, These problems will be easily solved. We believe that with the continuous improvement of people's consciousness, China will be the most extensive and powerful market for water-based exterior wall coatings in the future. For example, SREP series silicone emulsion paints made by BS Chemicals, Inc., Germany, have excellent durability, and have a good record of using 29 years of paint film on the external walls of buildings; Japan has recently The patent covers a new kind of water-based photocatalyst paint for exterior decoration of buildings. It is a water-based architectural exterior color paint that can remove contaminants on the surface of buildings by rainwater washing and photocatalyst technology. In addition, it It also has anti-mildew and anti-algae effects, and it also has the function of purifying exhaust gas emitted by automobiles. It should be noted that in the construction process of water-based architectural coatings, the surface treatment of the grass-roots level generally requires that the surface be solid, smooth, free of dust, oil, and dryness. Otherwise, it may cause defects such as paint defects or peeling of the paint. After the grass-roots floor is cleaned up, it is necessary to coat the grass-roots with a layer of primer, and each series of products has its own matching primer coating. After the primer is dry, the diluted waterborne coating can be applied by rolling, brushing, or spraying. In addition, since the film formation of waterborne coatings is conditional and cannot be less than 5 degrees Celsius, it is not suitable for winter construction, which also presents a new topic for the development of waterborne architectural coatings.

Water-based automotive coatings: Automotive coatings are the fastest-growing paints, with the second only to architectural coatings, ranking second, and the highest performance requirements, among which the highest requirements are for car painting. Therefore, the car painting materials often represent the highest level and development of the contemporary paint industry. BASF, PPG and DuPont are the world's top three automotive coatings suppliers, including DuPont Specialty Coatings, which has a market share of 46%; BASF Corporation has a 28% market share; and PPG Corporation has a 24% market share.
The electrophoretic paint is generally used as the primer for automobiles. The electrophoretic paints currently used in our country are generally the third and fourth generation products: Akzo's D2035, Herberts' 8911, PPG's ED4, Kansai's HB2000, 9120, and Herbs. The G1083, G1183, AQUAEC3000, BASF's FT25, etc.; and currently the world's major automotive company production lines are used are high rate of swimming, high corrosion resistance, low density, low solvent content, high bath stability, anti-pollution The fifth generation cathodic electrophoretic primer with many features, such as strong ability and low baking temperature. At present, the 6th generation product EC6350 developed by PPG has been put on the market. The 7th generation of products has been commercialized. The 8th generation of products has been successfully developed in the laboratory. The development of the new generation has also begun. The main features of the new generation of cathodic electrophoresis are : High penetration rate, low base ratio, good corner coverage, and lead-free and tin free. In addition, its double-layer electrophoresis has been successfully developed. After the primer coating, the flatness of the coating surface is relatively poor, and some of them are invisible to the naked eye, while the middle coating plays a role of filling the surface. When the top coating is applied, the fullness of the coating appearance is greatly increased. Improvement, this is a very important step to optimize the appearance of automotive coatings. Therefore, the intermediate coating requires good adhesion with the primer finish, and has a certain degree of elasticity and filling, good sandability, can cover the substrate itself rough The minor defects caused by the degree of improvement of the decorative nature, but also to reduce the damage of ultraviolet ray to the primer.

At present, the waterborne intermediate coatings in Western Europe are mainly waterborne polyester-amino resin type and blocked isocyanate polyurethane type, and the production process is relatively mature. The water-based development of Japan's mid-coating coatings is also fast, such as the water-based waterborne coatings developed by Kansai Paint Co., Japan. Polyamide amino paint, the construction of the viscosity of the solid has reached 61%, VOC content of 12%, drying conditions 140 °C × 30min, to achieve the same performance and solvent-based paint. In the automotive paint VOC emissions, the top paint discharge amounted to 60%, which is the “pollution big” in the automotive paint. Therefore, the water-based car paint has great significance in the water-based automotive paint. (to be continued)