The effect of structure-property relationships on the formability of pigmented polyester coatings

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