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Theoretical and experimental aspects of paint film leveling

Presentation held at Coatings for the Next Decade, 1st European Technical Coatings Congress, ETCC 2012, 4-6 June 2012, Lausanne, Switzerland. FATIPEC-OCCA Congress
: Hager, Christian

Präsentation urn:nbn:de:0011-n-2363697 (2.7 MByte PDF)
MD5 Fingerprint: fa40665b10b14fa94ff5871fde79e762
Erstellt am: 12.4.2013

2012, 22 Folien
European Technical Coatings Congress (ETCC) <1, 2012, Lausanne>
FATIPEC - OCCA Congress <2012, Lausanne>
Vortrag, Elektronische Publikation
Fraunhofer IPA ()
GSaME; Lackfilmverlauf; paint; appearance; paint film leveling; orange-peel; spray painting; numerical simulation; numerische Simulation; Qualität; Lackierung; Simulation

Next to color and gloss, the leveling of paint films is the most important criterion for the evaluation of coating quality of high-quality products. In case of incomplete leveling the surface of the paint film after drying and curing shows a more or less strong "orange-peel structure".
For paint films that are applied by using spraying techniques the random statistical superposition of the paint droplets during film formation is main cause for the occurrence of orange-peel structure.
The particle size spectrum of the paint droplets, surface tension, initial viscosity of the coating material directly after the deposition, the temporal behavior of the viscosity during evaporation and baking phase and the force of gravity (horizontal / vertical leveling) are the main influencing factors for the so-called "intrinsic" surface structure of paint layers. In addition, the roughness respectively waviness of the substrate surface is mapped onto the surface of the applied paint film due to two different processes, namely substrate mapping by paint film shrinkage, and flow-induced structure generation for the vertical case.
Some information on the influence of the parameters mentioned above is known from experiment. However, for a specific and fast optimization of painting quality, for instance with the aim of achieving a homogeneous appearance on multi-substrate systems, there is a need to relate the interactions of these parameters based on universal numerical models.
The paper deals with various models concerning this complex issue, and shows new results regarding the interrelation between the various parameters by combining a shot-noise model (superposition of droplets) with lubrication theory (leveling driven by surface tension).