[China Aluminum Industry Network] 1 Introduction GB 5237.3-2008, "Aluminum Alloy Building Profiles - Part 3: Electrophoretic Coating Profiles," is primarily based on GB/T 8013-2007, with references to Japan's JIS H8602-1992 and the U.S. AAMA 612-02 standards. At the time of its development, the performance requirements and indicators of this standard were comparable or even exceeded those of JIS H8602-1992. It also introduced additional requirements for hydrochloric acid resistance and mortar resistance, considering the specific conditions of construction applications. However, since then, JIS H8602 has been revised, and the updated JIS H8602-2010 has significantly improved performance requirements. Meanwhile, the ISO proposal on aluminum anodized electrophoretic coating composite films has also undergone continuous improvements. This article provides a brief comparison of the main differences between China’s GB 5237.3-2008, Japan’s JIS H8602-2010, and the ISO proposals from both countries. 2 Key Differences Between China’s GB 5237.3-2008, Japan’s JIS H8602-2010, and the ISO Proposal 2.1 Weather Resistance Weather resistance is a crucial performance indicator for architectural electrophoresis aluminum alloy profiles. The Japanese standard and the ISO proposal divide the artificial accelerated weathering test using xenon lamps into four levels: 350h, 1000h, 2000h, and 4000h. In contrast, China’s GB 5237.3-2008 divides the test time into three levels: 1000h, 2000h, and 4000h. Since the Chinese standard mainly focuses on outdoor use, it does not include the 350h test, but the other three levels meet the requirements of both the Japanese standard and the ISO proposal. Although the three standards have minor differences in their weather resistance requirements, they differ in the environmental conditions specified for the use of the composite film. While China’s standard only specifies the weatherability requirements for each grade, it does not clearly define the usage environment. On the other hand, JIS H8602-2010 and the ISO proposal provide guidance on the appropriate environments for each membrane type. For instance, a 350h test is recommended for indoor use, 1000h for normal outdoor environments, 2000h for harsh outdoor conditions (e.g., areas contaminated by sea salt), and 4000h for seaside or high UV exposure areas. The author believes that these environmental recommendations have practical significance and can help customers choose the right film grade. 2.2 Joint Corrosion Resistance Unlike China’s standard, JIS H8602-2010 and the ISO proposal specifically require joint corrosion resistance tests after fluorescent UV lamp weathering. Several factors contribute to this approach. 2.2.1 Operational Factors From an operational perspective, weather resistance tests are time-consuming, often requiring thousands of hours. Many manufacturers lack the time or resources to wait for full results and instead opt for shorter performance tests. 2.2.2 Practical Considerations From a practical standpoint, using a 313nm UV lamp for accelerated weathering, with conditions closer to natural ones—such as 30 W/m² irradiation, 4 hours dry, 4 hours wet, cycled over 240 hours—followed by a CASS test, better reflects real-world conditions. Aluminum doors, windows, and curtain walls are exposed to UV radiation and must withstand acid rain, smoke, mud, bird droppings, and detergents. 2.2.3 Coating Factors From a coating perspective, 240 hours of UV exposure simulates short-term aging. If unstable monomers are used, passing this test becomes challenging. High-quality acrylic resins with good light stability ensure no chalking, which is essential for long-term durability. The author once observed a window made of electrophoretic profiles from a well-known Shandong factory, where the exterior paint had completely deteriorated within a few months. To prevent such issues, manufacturers must carefully adjust the ratio of different monomers during polymerization to control free monomer content and ensure uniform molecular weight. This improves both corrosion and weather resistance. Using long-chain acrylates enhances light stability, increases molecular weight, and allows self-emulsification, improving overall performance while reducing solvent dependence. Japanese electrophoretic coatings typically use emulsified paints, which are more environmentally friendly. 2.2.4 Microscopic Factors From a microscopic perspective, xenon lamps emit wavelengths between 340nm and 410nm, with peak at 340nm. Shorter wavelengths mean higher energy, making it easier to detect stable coatings. If the film remains intact after UV exposure, it shows excellent corrosion resistance in subsequent CASS tests. If the molecular chain breaks, it severely impacts corrosion resistance. 2.2.5 Data from Japan Although the new Japanese standard doesn’t specify oxide or electrophoretic film thickness, thin films struggle to pass joint corrosion tests. This sets a new and stricter requirement for electrophoretic coatings, marking progress in energy efficiency and performance. 2.2.6 Future Trends in Coatings Looking ahead, weather resistance will remain a key factor for architectural aluminum alloys. With varying environmental conditions, different standards can be applied, enabling targeted coating selection. Acrylic-based polymers offer high weather resistance due to their light stability. Cross-linking agents like hexamethoxymethyl melamine improve hardness, luster, and color retention. Cathodic electrophoretic coatings with better lightfastness are also gaining popularity, offering superior corrosion resistance and a promising future for architectural coatings. In terms of application, electrodeposition is ideal for automated, efficient production. It achieves up to 95% coating utilization, compared to 82% for anodic electrophoretic coatings. The ED process ensures uniform film thickness, enhancing corrosion and weather resistance, especially for complex geometries. 3 Other Important Issues in the Standard 3.1 Hardness Coating hardness is a basic performance indicator for electrophoretic composite membranes. Two common methods are indentation hardness and pencil hardness tests. Thick coatings use indentation, while thin coatings use pencils. Given the thin nature of electrophoretic coatings, GB 5237.3-2008 and the ISO proposal use pencil hardness tests, while the Japanese standard does not specify hardness. China’s standard requires Class A and B to be at least 3H, and Class S to be 1H, whereas the ISO proposal demands all grades to be at least 3H. Pencil hardness depends on coating properties and curing degree, with thinner films generally harder. 3.2 Gloss Neither the Chinese nor Japanese standards specify gloss, while the ISO proposal outlines a test method, though quality and data requirements are negotiated between supplier and buyer. Gloss is measured using a 60-degree gloss meter, with multi-angle meters for more detailed readings. The surface must be flat, with a flatness of 0.18 or less. 3.3 Adhesion All three standards require adhesion to reach 0 (25/25). Cross-cutting is commonly used, and the tool must be sharp to expose the metal substrate. After water immersion, any peeling indicates poor adhesion, affecting corrosion resistance. 3.4 Salt Spray Corrosion Resistance Salt spray tests include NSS, AASS, and CASS, with CASS being the most aggressive. It is critical for coastal areas. China’s standards only specify 24h and 48h, while Japan and the ISO proposal require 24h, 72h, and 120h, with 120h for outdoor use. This makes the latter standards more stringent. 3.5 Alkali Resistance Alkali resistance requirements are similar across standards, with tests conducted at 20°C. Fully cured coatings usually pass, but under extreme conditions, a second boiling water test may be needed. Resin type also affects results. 3.6 Composite Film Thickness The new Japanese standard requires an oxide film thickness of at least 5μm, without specifying electrophoretic film thickness. However, experiments show that an oxide film of at least 6μm is necessary for even electrophoretic coating. Japanese companies often produce films over 8μm. For joint corrosion testing, 9+7 is recommended, but Chinese factories face challenges due to inconsistent oxidation and coating quality. Electrophoretic film thickness significantly affects properties like CASS and weather resistance. 3.7 Natural Weather Resistance Natural weather resistance is vital for electrophoretic aluminum profiles, as buildings are not easily replaced. China’s GB 5237.3-2008 and the ISO proposal mention natural weathering, but their specific requirements are vague. The author suggests focusing on natural weathering research, despite its complexity, as it better reflects product durability than artificial tests. 4 Conclusion Despite some differences between China’s GB 5237.3-2008, Japan’s JIS H8602-2010, and the ISO proposal, there is reason to believe that with industrial development and economic globalization, China will continue to refine its standards, reduce gaps with advanced nations, and eventually propose its own advanced standards. This will provide a stronger legal foundation for the growth of China’s industries. 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