Choi Woo-Chan, Gavande Vishal, Kim Dong-Yun, Lee Won-Ki
Central R&D Center, Dongkuk Steel Mill, Nam-gu, Busan 48481, Republic of Korea.
Division of Polymer Engineering, Pukyong National University, Busan 48513, Republic of Korea.
Polymers (Basel). 2023 Feb 10;15(4):880. doi: 10.3390/polym15040880.
UV-curable coatings have numerous advantages, including environmental sustainability due to 100% solid content, economic feasibility attributable to relatively fast curing time, decent appearance, mechanical properties, chemical resistance, and abrasion resistance. However, UV-curable polyurethane acrylate coatings on metals apparently restrict their engineering applications owing to low mechanical properties and poor thermal stability, giving UV-curable coatings less flexibility and formability. In this study, we evaluated the property change of films according to the type of reactive diluents that lowers the viscosity of UV-curing coatings for pre-coated metal and has a substantial effect on the curing rate, viscoelastic properties, adhesive properties, and flexibility of the film. Moreover, there are many changes in the properties of coatings according to varied curing conditions in order to evaluate the oxygen inhibition phenomenon during the curing process in the atmosphere. In particular, to evaluate the effect of reactive diluents on forming formability, which is the most crucial property for the pre-coated metal, this study used conventional formability tests, such as t-bending or the Erichsen test. Moreover, a cross-die cup drawing mold with a similar form as failure and Safety Zone was utilized in order to obtain clearer information on its actual formability. The analysis on the effect of failure and safety zone on the material used in press forming was conducted by assessing limit punch height and forming a limit diagram of the manufactured film according to varied reactive diluents.
紫外光固化涂料具有众多优点，包括因100%固体含量而具备环境可持续性、由于固化时间相对较快而具有经济可行性、外观良好、具备机械性能、耐化学性和耐磨性。然而，金属上的紫外光固化聚氨酯丙烯酸酯涂料由于机械性能低和热稳定性差，明显限制了它们的工程应用，使得紫外光固化涂料的柔韧性和可成型性较差。在本研究中，我们根据活性稀释剂的类型评估了薄膜的性能变化，这些活性稀释剂可降低预涂覆金属用紫外光固化涂料的粘度，并对薄膜的固化速率、粘弹性、粘附性能和柔韧性有重大影响。此外，根据不同的固化条件，涂料的性能会有许多变化，以便评估大气中固化过程中的氧抑制现象。特别是，为了评估活性稀释剂对成型性的影响，成型性是预涂覆金属最关键的性能，本研究采用了传统的成型性测试，如t型弯曲或埃里希森试验。此外，还使用了一种与失效和安全区形状相似的十字模杯形拉伸模具，以便更清楚地了解其实际成型性。通过评估极限冲头高度，并根据不同的活性稀释剂绘制制成薄膜的极限图，对失效和安全区对冲压成型所用材料的影响进行了分析。
