Breakthrough and application of UV curing powder coatings on heat-sensitive alloy substrates
In the metal coating industry, powder coatings hold a prominent position due to their solvent-free nature, simple processing, low energy consumption, and outstanding environmental friendliness. However, traditional thermosetting powder coatings require curing at temperatures of 150-200°C, making them particularly challenging for heat-sensitive alloy substrates such as magnesium-aluminum alloys and some copper alloys. High temperatures can easily cause changes in the substrate's metallographic structure, deteriorate its mechanical properties (such as reduced strength and toughness), and even cause deformation, significantly limiting the application of powder coatings.
UV-curable powder coatings utilize a "melt-UV curing" process, where they melt and level at a preheat temperature of 90-110°C, followed by rapid curing (5-60 seconds) using ultraviolet light (wavelength 320-450nm). This process fundamentally reduces thermal damage to heat-sensitive alloy substrates. Its core advantage lies in shifting the curing process from heat-dependent to light-dependent, achieving low-temperature curing through a photochemical reaction. This process has become a hot topic in coatings research and application.
1. Separate Process and Low-Temperature Advantages: UV-curable powder coatings utilize a separate melt-UV curing process. The melt-leveling stage requires only 90–120°C, significantly lower than the 150–200°C required for traditional thermosetting coatings. This stage only allows the powder to melt and level, without any cross-linking reaction. This prevents grain boundary melting, mechanical property degradation, or deformation in heat-sensitive alloys caused by high temperatures.
2. Energy Efficiency and Environmental Protection: Curing consumes 70% less energy than traditional processes because it eliminates the need for prolonged, high-temperature baking (traditional processes require 15–30 minutes, while UV curing takes only seconds). It also achieves zero VOC emissions and contains over 40% bio-based components, in line with green manufacturing trends.
UV-curable powder coatings fundamentally address the high-temperature damage issues faced by heat-sensitive alloys through a separate process of low-temperature melt leveling and photochemical curing. Their core advantages include: a) thermal damage suppression (substrate temperature ≤ 110°C); b) energy efficiency and environmental friendliness (70% reduction in energy consumption, zero VOC); c) performance enhancements (quantitative indicators such as adhesion and corrosion resistance significantly outperform those of traditional coatings); and d) suitability for complex components (UV directional curing and EB hybrid curing support localized repair).
With the continuous advancement of resin synthesis technology (such as the improved low-temperature fluidity of crystalline resins) and the maturation of the industrial chain, UV-curable powder coatings have moved from the laboratory to industrial production, providing reliable protection for lightweight, heat-sensitive alloy components in aerospace, electronics, high-end equipment, and other fields. In the future, this technology will further promote the green manufacturing innovation of "replacing paint with powder," becoming the preferred surface treatment solution for heat-sensitive substrates.
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