Integrated Modeling and Simulation for Improved Reactive Drying of Clearcoat

Abstract

Clearcoat filmbuild is one of the main concerns for painting quality in automotive paint shops. In operation, clearcoat is sprayed on the vehicle surface and then baked in an oven where solvents are removed and cross-linking reactions take place. Because of operational complexity and measurement difficulty, the process dynamics is basically unknown. Thus, the operational settings in the oven are solely experience-based. Hitherto, the studies on automotive oven operations has been only at the lab level. To significantly improve clearcoat filmbuild, a model at the plant floor level should be developed. In the present work, a first-principles-based, simplified, integrated dynamic model is developed to characterize the clearcoat reactive drying process in an oven. It is demonstrated that the model can provide satisfactory long-term predictions of filmbuild, facilitate a thorough analysis of drying/curing operations, and form the basis for developing optimal operational strategies for improving film quality and reducing defects.

Integrated multiscale product and process control of polymeric coating curing

“…In the process, the vehicle bodies covered by layers of wet films travel one by one on a conveyer at a constant speed through a curing oven. The oven is usually divided into a number of zones so that different heating mechanisms (i.e., radiation from oven walls and hot air convection) can be applied under different operating conditions [10]. The oven wall temperature and the convection air temperature are controlled by adjusting the flow rate of fuel fed into the furnace.…”

“…The coating quality is assessed by quantifying the solvent residue in the film and the elastically effective crosslink density (EECD) of the 3D polymer network in a coating. In the dry film, the solvent content must be lower than a certain value [10]. For a specific polymeric material, there exists a preferred EECD region.…”

“…A set of macroscopic models have been developed for the solvent-borne based coating drying and curing [6][7][8][9][10]. Those models can generate very valuable quantitative information about how (i) the coating topology (from wet to dry) could be dynamically changed, (ii) the solvent could be smoothly removed, (iii) the crosslinking reaction could take place, and (iv) common defects could be successfully detected, analyzed, and prevented.…”

Multiscale Characterization of Automotive Surface Coating Formation for Sustainable Manufacturing

“…The solvent diffusion and evaporation, and film thickness change modeled by Lou and Huang are adopted in this work [16]. By concerning possible defects on the film surface, the crater formation model by Evans et al [32], for instance, is enhanced to study crater formation in curing by incorporating the correlation of the paint viscosity, the resin molecular weight, the solvent amount, and the film temperature.…”

“…Efforts have also been made to model oven baking operations [13 15], most of which are at the lab level, studying the curing of small coated substrates. Lou and Huang [16] were among the earliest to introduce a first-principlesbased, integrated dynamic modeling approach for characterizing the dynamics of oven curing. Based on that model, Xiao et al [5, 17 19] solved two classes of curing optimization problems and proposed a proactive quality control approach.…”