Development and bottleneck of the hottest waterbor

Development and bottleneck of water-based road marking paint

development and bottleneck of water-based road marking paint

November 16, 2004

1 Preface

in the 21st century, the total mileage of China's roads has reached 1.25 million kilometers, and the passenger and freight volume undertaken by China's roads has accounted for 88.7% and 99% of the total national transportation volume, which is the foundation and lifeline of national economic development. However, compared with developed countries, China has insufficient transportation facilities and weak management. Take road markings for example, except for large and medium-sized cities and high-end highways, most roads are generally unmarked, while 90% of the coatings used on marked roads are normal temperature dry solvent coatings, mainly hot-melt coatings based on C5 petroleum resin and normal temperature solvent coatings based on acrylic resin

the VOC content of solvent based marking paint is as high as 650g/l, which will pollute the environment after volatilization. In order to ensure the sustainable development of the national economy, the state has formulated strict environmental protection policies. In 1992, the CPC Central Committee and the State Council approved the "ten countermeasures for China's environmental development" and the "China's 21st century project". People's awareness of environmental protection is also growing. "Return me a piece of blue sky, return me a piece of green land, give me a glass of water, and send me a burst of fresh air" has become an urgent desire of people. In order to complete the plant before the end of the project, improve the production and quality, and be in line with international standards, many enterprises are currently engaged in ISO 9000 series quality management certification, and are promoting environmental management system certification (ISO 14000). The difference between this certification and ISO9000 is that it requires a lot of water to wash the liquid products left in the pipeline, which requires increasing environmental awareness in the production process of enterprises, that is, to meet environmental protection requirements. Therefore, it is of great and far-reaching practical significance to advocate the production of environmentally friendly waterborne road marking coatings in the paint industry, and it is the general trend to meet the requirements of ISO 14000 quality management

2. Development overview at home and abroad

as early as 1996, the famous "66" regulation was proposed at the Los Angeles conference. This regulation limits the emission of organic solvents. At present, "66" has developed to "1113 regulation", which stipulates that the emission of organic solvents from industrial coatings decreased from 420g/l in 1990 to below 150g/l in 2000. Therefore, in terms of traffic coatings, 90% of solvent based marking coatings in the United States have been replaced by water-based road marking coatings; 70% of the Netherlands was replaced; Germany and Spain also completely adopted water-based road marking paint in 1998; Sweden and Finland 95% water-based road marking paint; Australia also has 90% water-based road marking paint; Japan also has its own patent for waterborne road marking paint in 1996. In recent years, some powerful marking paint manufacturers in China have invested a lot of effort to develop and produce water-borne road marking paint, which has been tested on urban roads and highways and achieved good results. It can be expected that water-based road marking paint will have a rapid development in China, especially Beijing's successful Olympic bid to host a green Olympic Games and an environmental protection Olympic Games, so the marking of road markings must be pollution-free

3. Problems to be solved

3.1 As a new product, water-based road marking paint should have its own product standards. Some technical indicators need to be agreed, such as the VOC content, which is limited to 150g/l or even 125g/l in foreign countries. At the same time, it is also required that compounds containing heavy metals should not be added in the production process of products, and the total content should be less than 500mg/kg (calculated by lead). The author believes that as a developing country, China's goal is to move closer to the international advanced level, but there must be a transition process. Just like China's automobile exhaust emission standards, currently only the European No. 2 standard is implemented, while others have already implemented the more stringent No. 3 standard. Considering the driving safety on the expressway, the new standard should put forward anti-skid requirements for the markings drawn by water-based road marking paint, and the specific SRT value should be determined according to the test and national conditions. In addition, the index of retroreflection coefficient of markings should also be improved. In addition, reasonable technical indicators should be set for the surface drying time, wear resistance and water resistance of the film

3．2. To formulate appropriate construction technology, water-based road marking paint has strict requirements on construction technology, so it is necessary to formulate correct construction technology. During construction, attention should be paid to the cleanliness of the road surface, construction temperature, humidity, wind speed and the distribution method of glass beads. It is not suitable for construction when the relative humidity is greater than 85% or the temperature is lower than 10 ℃. Therefore, it is hoped that paint manufacturers and foreign brand paint agents can provide after-sales services, regularly hold customer promotion and application courses, and teach construction methods and precautions. The thickness of the coating film has a great impact on the service life of the marking line and the low-temperature groove of the sample. Special attention should be paid to the construction. It should not be too thick or too thin. The properties of water-based road marking paint and solvent based road marking paint are different in such repeated rolling and sampling, and their requirements for storage conditions and construction machinery are not exactly the same. Therefore, the storage method and construction machinery should be appropriately changed, such as the storage barrel should be rustproof, and the paint storage tank and pipeline of construction machinery should be made of stainless steel

3．3. Diversification of base materials. The base materials of waterborne road marking coatings can not only introduce foreign advanced quick drying latex, but also be synthesized by themselves. The latex used can have a variety of structures, including epoxy acrylic composite latex, organosilicon modified acrylic composite latex, and even inorganic and polymer colloidal silica acrylic composite latex. Only through the comparison of various performance tests can the most reasonable base material be found

3．4. Improve the water resistance. The water-based coating has a natural affinity with water, so the dispersant, wetting agent and their dosage should be selected in the formula to improve the water resistance of the film. After the long-term immersion of the film in water, the swelling of the base material will cause a lot of volume expansion, resulting in stress on the interface between the road and the film. When the stress reaches a certain degree, the film will peel off from the road. Generally, the pavement of expressway is equipped with a permeable layer. After the rain, the markings will not be soaked, so the impact is small. However, urban roads rely on sewers for drainage. Once the sewers are blocked, the water cannot be drained out, and the markings will be soaked for a long time, resulting in hollowing, foaming, and even peeling. Therefore, when water-based road marking paint is used in urban roads, corresponding countermeasures should be taken. Cement pavement is also unfavorable to the marking made by water-based road marking paint, because there are many capillary tubes in the cement pavement that cannot be observed by the naked eye, and there is a large amount of water in the capillary tubes, which will erode the marking for a long time. Once the water evaporates, a certain pressure will be generated to promote the film to fall off. It is suggested to make some improvements in the construction process, such as whether a layer of hole sealing primer can be painted on the cement pavement before scribing

3．5. Other waterborne road marking coatings will thicken during storage. If the filler is well dispersed, it is not a problem. As for the mechanical strength of the film, it has little effect on the service life of the film. At present, the methods of improving the particle size matching of fillers and spreading glass beads are mostly used to improve the mechanical strength of the coating. In short, water-based road marking paint has not been popularized and applied in China for a long time, and we will always encounter one or another problems, which can be properly solved as long as we take it seriously. Water based road marking paint solves the pollution problem of road marking paint, so it has a promising future