Pre-painted metal sheet (PPM) is used in applications from domestic appliances to architectural cladding. The coating provides excellent aesthetics and corrosion protection, but must possess excellent formability to not fail due to the large strains applied during the folding and hemming processes used to produce components. Therefore it is important to understand how the coating formulation affects the free-film properties and formability of a coating system. Polyester coatings crosslinked with hexa(methoxymethyl)melamine (HMMM) with a T_g of ∼ 40 °C were used, pigmented with TiO₂. The glass transition temperature was increased by increasing the crosslinker content (from 5 % to 30 %), decreasing the adipic acid content (from 24 % to 12 %) and decreasing the molecular weight (from M_n = 3300 g/mol to M_n = 1500 g/mol). The chemical structure of the resin had little effect on the formability of the coatings when the test temperature was normalised with respect to T_g. The formability measured using the Erichsen cupping and T-bend tests is related to the tensile properties of the free-films. The damage induced by the T-bend is greater than that by the Erichsen cupping test due to the higher applied deformation rates in T-bend tests. Increasing the apparent yield and fracture stress increases the likelihood of damage at lower deformation levels, whilst increasing the strain to failure decreases the likelihood of damage in both the T-bend and Erichsen cupping tests. The strength of these correlations reduces with an increase in T-bend level as the magnitudes of the strains applied are reduced. This work takes a holistic approach to correlate structure and tensile properties with formability in both the Erichsen cupping test and T-bend test for the first time, enabling industry to improve coating performance significantly but cost-effectively.

彩涂金属板（PPM）用于从家用电器到建筑立面的各种应用。该涂层具有出色的美观性和防腐蚀性能，但必须具有出色的可成型性，以确保不会因在用于生产零件的折叠和卷边过程中施加的大应变而失效。因此，重要的是要了解涂料配方如何影响涂料体系的自由膜性能和可成型性。使用_Tg为约40℃的用六（甲氧基甲基）三聚氰胺（HMMM）交联的聚酯涂料，并用TiO ₂着色。通过增加交联剂的含量（从5％到30％），降低己二酸的含量（从24％到12％）和降低分子量（从M到M）来提高玻璃化温度。_n = 3300 g / mol至M _n = 1500 g / mol）。当相对于T _g标准化测试温度时，树脂的化学结构对涂层的可成型性影响很小。。使用Erichsen拔罐和T形弯曲试验测量的可成型性与自由膜的拉伸性能有关。由于T形弯曲试验中较高的变形速率，T形弯曲引起的损伤大于Erichsen拔罐试验。在较低的变形水平下，增加表观屈服强度和断裂应力会增加损坏的可能性，而在T形弯曲和Erichsen拔罐试验中，增加破坏应变会降低损坏的可能性。这些相关的强度随着T形弯曲水平的增加而减小，这是因为所施加的应变的大小减小了。这项工作首次采用整体方法，将结构和拉伸性能与可成形性相关联，既在Erichsen拔罐测试中也进行了T型弯曲测试，