[China Aluminum Industry Network] 1 Introduction GB 5237.3-2008 "aluminum alloy building profiles Part 3: electrophoretic coating profiles" is mainly based on GB/T 8013-2007, with reference to Japan's JIS H8602-1992 and the United States AAMA 612-02. At the time of formulation, the performance requirements and indicators of the standard have reached or even exceeded the Japanese JIS H8602-1992 requirements, and have increased the performance requirements of hydrochloric acid resistance and mortar-resistance according to the features used in construction. However, at present, Japan JIS H8602 has been revised, the new JIS H8602-2010 standard has been greatly changed compared with JIS H8602-1992, the performance requirements have been greatly improved, and the aluminum anodized electrophoretic coating composite film specification ISO proposal is Over the past few years has also been constantly revised and improved. This article will give a brief overview of the main differences between China's GB5237.3-2008 standard and Japan's JIS8602-2010 standard and the ISO proposals of China and Japan. 2 Content differences between China's GB5237.3-2008 and Japan's JIS H 8602-2010 and ISO proposal 2.1 Weather resistance Weather resistance is an important performance index of architectural electrophoresis aluminum alloy aluminum alloy profiles. The Japanese standard and ISO proposal divide the test time of artificial accelerated weather resistance of xenon lamps into four levels of 350h, 1000h, 2000h and 4000h, while the national standard of China will accelerate the weather resistance of xenon lamps. The test time for sexuality is divided into three grades: 1000h, 2000h and 4000h. Since the Chinese standard mainly considers outdoor use, compared with Japan and the ISO proposal, there is no test time of 350h, and the other three grades meet Japanese standards and ISO proposal requirements. quite. Although the three standards have little difference in the weather resistance requirements of the composite film, the three standards have different requirements for the use environment of the composite film. The three-stage composite membrane specified by China's standard only specifies the weatherability requirements of each file, but it does not clearly define the environment in which the composite membrane is used. Japanese JISH8602-2010 and ISO proposal provide guidance on the environment for use of each membrane. It is recommended that the electrophoresis composite membrane with a test time of 350h be used in indoor environments and the electrophoresis composite membrane with a test time of 1000h be used in outdoor normal environments ( Such as ordinary cities, green areas and industrial areas, the electrophoresis composite membrane with a test time of 2000 hours is used in outdoor harsh environments (such as corrosive and degradable areas contaminated by sea salt), and electrophoretic composite membranes with a test time of 4000 hours For seaside areas, outdoor harsh environments and strong UV exposure areas. The author believes that the use environment recommended by Japan's JISH8602-2010 and ISO proposal has a certain practical significance and can guide customers to choose composite film grades. 2.2 Joint corrosion resistance Different from our country's standard, Japan's JISH8602-2010 and ISO proposal specially stipulates the joint corrosion resistance requirements of the artificial accelerated weathering resistance test of fluorescent UV lamps before combined with the salt spray test. The author believes there are mainly the following factors. 2.2.1 operability factors From an operability point of view, the weatherability test has taken a long time, often at the cost of thousands of hours. Many manufacturers do not have the time or the time to wait for the inspection report, but instead use other relevant performance tests that are shorter. 2.2.2 Realistic factors From a practical point of view, when using the 313-nm UV lamp to artificially accelerate the weathering test, the test conditions that are closer to natural conditions are selected, ie, the irradiation intensity is 30 W/m 2 , 4 h drying, 4 h wet, cycling for 240 h, and then CASS Test this joint corrosion resistance test can better reflect the actual use. Because the aluminum doors and windows and the curtain wall are exposed to ultraviolet radiation, they must also withstand natural acid rain, smoke, mud, bird droppings, and detergents. 2.2.3 Coating Factors From the coating point of view, exposure to UV rays for 240 hours is equivalent to a short-term aging experiment. If you do not choose long-chain carbon acrylic monomers with good stability or superiority, simply reduce the cost, this test is very difficult to pass. In addition, the polymerized resin has good light stability and does not degrade, that is, it does not chalk in nature. The author once saw a window made of an electrophoretic profile produced by a famous aluminum factory in Shandong Province in a commercial house not yet sold by the sea in Shandong Province. The paint film facing the outside has been completely pulverized and disappeared. In order to eliminate this situation, in the production process, a variety of monomers with different properties must be adjusted in accordance with the reactivity ratio of the polymerization reaction, and the proportion of the monomers to be fed at each moment should be adjusted so as to prevent the polymerization reaction from occurring. The amount of free monomer in the polymer is small, and the molecular weight is uniform (heat loss can be better controlled within 3%), thereby simultaneously improving the corrosion resistance and weather resistance of the coating film. The use of suitable long-chain acrylates is beneficial to light stability, and the molecular weight of the polymer can be made larger, and the resulting resin will be self-emulsified. Corrosion resistance, weather resistance, and mechanical properties are all improved, and the swim rate is also increased, so that the dependence of the coating on the co-solvent is greatly reduced, and the reduction of the organic solvent is favorable to the environment (Japanese paint factory electrophoretic coating in Japan Almost all emulsified paint). 2.2.4 Microscopic factors From a microscopic point of view, xenon lamps are often used, and their wavelengths are generally selected between 340nm and 410nm (peak at 340nm) and also belong to the ultraviolet range. However, for ray, its particle energy = hν, where h is Planck's constant and ν is the frequency of this ray. That is, the shorter the wavelength, the greater the energy of the ray particles, and the more stable the coating film can be detected in a short time. If the linked film is bombarded by high-energy particles without chain scission (powdering), the CASS test in the subsequent sequence will show excellent corrosion resistance. On the contrary, if the molecular chain breaks after 240 hours of UV irradiation. (This is not easy to see in a simple weatherability test), it will have a great impact on the corrosion resistance in the subsequent CASS test. 2.2.5 Related data provided by Japan Although Japan's new standard does not specify the thickness of the oxide film and the electrophoretic coating film, it is difficult to pass the combined corrosion resistance test if the oxide film or the electrophoretic film is too thin. At the same time, this is also a new and higher requirement for electrophoretic coatings. It is a step forward in terms of saving energy and improving performance. 2.2.6 factors for the future development of coatings From the perspective of the future development of coatings, weatherability is an important performance indicator for aluminum alloy building profiles. However, due to the differences in the environment and regions in which they are used, different standards can be adopted. Thus, targeted selection of coatings can be made. Polymers based on acrylic acid and their esters have high weather resistance. This is mainly determined by monomers. It is formed by polymerization and has strong stability to light. If the monomers are properly selected, the coating will have excellent gloss retention. This resin is much better in weather resistance than the polymer formed by polycondensation. As such a coating must also have excellent corrosion resistance, the key to the formation of cross-linking of the coating film, using hexamethoxymethyl melamine as a cross-linking agent, in the curing process has a good cross-linking process The coating has high hardness, luster, color (no yellowing) and excellent weather resistance. In recent years, the emergence of cathodic electrophoretic coatings with better lightfastness is also a good choice, and its corrosion resistance is better. It is a polyamine resin structure and is made of IPDI (isophorone isocyanate) or aliphatic isocyanate. The resulting crosslinker has excellent weather resistance and can be made into CED. With CED, it is not necessary to use aluminum alloy oxidation, because in the electrodeposition process, the electrophoretic behavior is toward the cathode, the oxide film will be partially destroyed or completely destroyed, but this coating still has excellent corrosion resistance and weather resistance, there are many People think this should be the development trend in the field of architecture. With regard to the coating process, the use of electrodeposition method is an ideal method, which is advantageous to automated production with high efficiency. The utilization rate of the coating is as high as 95% (Aluminum anodic electrophoretic coating produced in China is generally 82%. The decrease in the efficiency is mainly related to the viscosity of the coating solution. And the anti-interference performance), the production of relatively stable quality coating film is formed by the ED, the process is the force of the electric field, first in the high current density coating, the formation of the film resistance becomes larger, but not formed The neighboring part becomes a part where the current density is high and the coating is continued, so that the parts of the workpiece are formed with a high resistance, and the coating film will not be thickened again when the ED is extended. For a geometrically complicated profile, each can be The coating film having a uniform film thickness at the site is called the ED's penetration rate performance, and is excellent in corrosion resistance, and also improves the weather resistance. 3 Other issues that need attention in the standard 3.1 Hardness Coating hardness is a basic performance index of electrophoretic composite membranes. There are mainly two methods for measuring the hardness of aluminum alloy surface treatment membrane at home and abroad. One is the indentation hardness test, and the other is the pencil hardness test. In general, the indentation hardness is usually used for the film thickness of the thick coating, while the thin film thickness is usually measured by the pencil hardness test. Due to the thin film thickness of the electrophoresis aluminum alloy profiles, the GB5237.3-2008 standard and the ISO proposal both use the pencil hardness test to detect the hardness of the electrophoretic paint film (the Japanese standard does not specify the film hardness). However, there are some differences between the performance standards specified in the two standards. China's standards stipulate that the hardness of Class A and Class B composite membranes should be at least 3H, and that of Grade S composite membranes should be at least 1H. The ISO proposal states that all composite membranes must have a hardness of at least 3H. When pencil hardness test is used, the pencil should be selected. The test should be performed with a special pencil for the hardness test of the film. The hardness of the paint is expressed by the hardness of the pencil. In the pencil hardness test, the hardness and stability of the test pencil have a great influence on the test results. The hardness of the pencils produced in various countries also has some differences. According to the actual experience, it is found that the German pencil pencil is harder, and China's pencil is relatively hard. The pencils and Japanese Mitsubishi pencils are relatively softer. If these two kinds of pencils must also be compared, Mitsubishi pencils are harder from a statistical point of view. The hardness of the coating depends mainly on the properties of the coating and depends on the degree of curing. In addition, the thickness of the coating film has a great influence on the hardness. When the coating film thickness is relatively thin, the hardness is relatively higher. 3.2 gloss Neither the Chinese standard nor the Japanese standard specifies the gloss, and the ISO proposal states the test method for gloss, but its quality and data requirements are negotiated between the supplier and the buyer. Gloss is usually measured with a 60-degree gloss meter. For more subdivisions, a multi-angle gloss meter can be used and measured with several angles. When measuring, it is required that the examined surface must be flat with a flatness of 0.18 or less. 3.3 Adhesion China's standards, Japanese standards, and ISO proposals all stipulate the adhering nature, and the three standards are all equivalent, all requiring that the adhesion should reach 0 (25/25). Adhesion has a great influence on the physical properties of the coating. The effect of corrosion resistance must not be underestimated. Cross-cutting is more commonly used. However, attention must be paid to the selection of the cross-cutting device to ensure that the tool is sharp and the coating can be scratched to expose the metal substrate. The secondary adhesion test after immersing in water is to imitate the impact on it after rinsing with rainwater. If the drop is more, it means that the coating film has not been completely bonded with the matrix material, or has been bulging. 3.4 Salt spray corrosion resistance Salt spray corrosion resistance test methods are usually three kinds, namely neutral salt spray test (NSS test), acetate spray test (AASS test) and copper accelerated acetate spray test (CASS test), wherein CASS test accelerated corrosion Sex is faster. The CASS test is a salt spray test that accelerates destruction under the action of copper salts. This test must be done, especially in coastal subtropical areas. Salt spray corrosion is quite serious under the conditions of use in the area, and now the environmental pollution Dyeing problems also increase the requirements for the preservation of materials. China's standards, Japanese standards, and ISO proposals all have requirements for salt spray tests, and stipulate different levels of use, but it should be noted that our standards only stipulate test times of 24h and 48h, while Japanese standards and The ISO proposal stipulates that the test time is 24h, 72h and 120h. It also requires that the areas with outdoor corrosion should meet the standard of 120h. The performance requirements are more stringent than the Chinese standards. 3.5 alkali resistance China's standards, Japanese standards, and ISO proposals have basically the same requirements for alkali resistance. Alkali resistance tests are performed at 20°C, because the difference in temperature has a great influence on the results. However, the experimental results collected by the author show that under the premise of complete curing, the coatings in our country can pass the alkali resistance test. If there is a lot of rain, hot and humid at the same time there is pollution in the area, you can consider the second alkali resistance test, that is to do the first resistance to boiling water test, and then do an alkali resistance test within one hour after drying, the results vary greatly, paint production The use of different resins by the manufacturer will also have a great impact on the results. 3.6 Thickness of Composite Film According to the new Japanese standard, the thickness of the oxide film should be 5μm or more and the thickness of the electrophoretic film should not be required. In fact, as we all know, the major difference between electrophoresis and other coating methods is that there is no coating dead corner, and the entire oxide film can be evenly coated. When coating, the resistance of the coating film becomes larger. Therefore, the coating particles will be deposited to the place where the resistance is small, but if the oxide film is too thin, the oxide film itself will cause serious non-uniformity of the resistance. Experiments show that if you want to get even coating of the electrophoretic film, oxide film on the main decorative surface Thickness should be at least 6μm. Therefore, I would like to say that even though the Japanese standard requires that the thickness of the oxide film be more than 5 μm, classify the performance according to the performance; but according to the author's understanding, the Japanese company controls the film thickness when the actual production is over 8 μm, which is also theoretical Explanation. At the same time, we carefully analyzed the data of Mr. Yuji Yamashima and found that, at least for the time being, in order to pass the joint corrosion resistance test, the better data selection is 9+7. However, due to the uneven quality of oxidation conditions and the quality of electrophoretic coatings in Chinese factories, the data should be applied to China, and we have no data to prove. As for the thickness of the electrophoretic coating, Japan's new standard has performed only the performance requirements, which triggered the panic of Japanese paint manufacturers. Everyone needs to reduce the film thickness as much as possible, and we know that the electrophoretic film Many of the properties, like CASS, weather resistance, etc., are very much related to the film thickness. 3.7 Natural weather resistance For electrophoretic aluminum profiles, weatherability is critical, because buildings are not likely to change doors and windows outside of the villa, so we often require aluminum doors and windows to have the same life span as buildings. China's GB5237.3-2008 standard and ISO proposal all have provisions for natural weathering, but their specific requirements are not clear enough. China's standards stipulate that performance indicators and test methods are negotiated between the supplier and the buyer. While the ISO proposal states that the natural weatherability test method, but the performance indicators are required to be negotiated between the supply and demand sides. In fact, the natural weatherability can truly reflect the durability of the product, while the artificial accelerated weather resistance test in the laboratory can reflect the weatherability of the product to a certain extent, but due to the accelerated destruction of the test, there is a certain distortion. risk. For this reason, the author believes that China's standards should focus on the study of natural weatherability. Although natural weatherability requirements are not very convenient for quality inspection, research and development for coatings is of practical significance. 4 Conclusion Although there are still some differences between China's standard GB5237.3-2008 and Japanese standard JIS8602-2010 and ISO proposal. However, we have reason to believe that with the development of industry and the spread of economic globalization, our country will pay more attention to improving the quality of standards, reduce the difference with advanced national standards, and even take one step forward and propose the so-called advanced countries. There are no standard items and testing methods, and efforts are made to improve various standards. Forming advanced standards that are more in line with China's national conditions will provide more favorable references and legal basis for the development of China's industries.
