The use of water-borne basecoats has become more prevalent in the automotive industry as an alternative to solvent-borne basecoat in order to reduce VOC emissions. However, water-borne basecoat needs a longer flash time at elevated temperature, so a dehydration oven is added to the process. Sometimes after dehydration, clearcoat application, and curing, surface imperfections in the form of pinholes or 'pops' occur. The research discussed in this paper studied the dehydration and paint application stages as possible causes of popping, and was conducted in three phases. In the first phase, a forward-time centre-distance finite difference model was used to simulate the water concentration in the layers of a paint film during dehydration at high and low temperatures. The second phase considered three paint application parameters. Factorial design of experiments was used to investigate their influence on popping phenomena. Also, the relation of pops to varying film builds was examined. The experiments of the third phase considered the influence of paint application parameters on pops, while maintaining a constant film build. Research showed that both dehydration and paint application stages have an impact on popping. However, additional research is necessary to understand the mechanistic behind those relationships.
Effect of dehydration and paint application parameters on popping
2007
28 Seiten, 11 Bilder, 3 Tabellen, 22 Quellen
Aufsatz (Konferenz)
Englisch
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