Abstract
This paper focuses on defining the reaction mechanism involved in the environmental etch of acrylic melamine-based automotive clearcoats via an identification of reaction products. This has been accomplished through a comparative study of products formed on acid treatment of neat crosslinkers, and those formed following laboratory acid treatment and field exposure of acrylic melamine clearcoat systems. Bulk elemental, X-ray photoelectron spectroscopy (XPS), and infrared (IR) analyses of sulfuric acid-treated melamine crosslinkers show that acid hydrolysis results primarily in the formation of melamine sulfate. Melamine sulfate formation was also observed following laboratory and field exposure of acrylic melamine clearcoat systems. These results confirm that the primary mode of melamine crosslink decomposition is through hydrolysis of acetal linkages and subsequent formation of melamine sulfates. However, data show that hydrolysis of pendent amino groups on the triazine ring also occurs.
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Ford Research Laboratory, P.O. Box 2053, MD 3083 SRL, Dearborn MI 48121. E-mail: pschmit1@ford.com
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Schmitz, P.J., Holubka, J.W. & Xu, LF. Mechanism for environmental etch of acrylic melamine-based automotive clearcoats: Identification of degradation products. Journal of Coatings Technology 72, 39–45 (2000). https://doi.org/10.1007/BF02698018
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DOI: https://doi.org/10.1007/BF02698018