Journal of Coatings Technology and Research

, Volume 15, Issue 1, pp 131–139 | Cite as

Thermal yellowing and photobleaching of automotive topcoats

  • Donald H. Campbell
  • Colin Wade
  • Kevin M. Turley
  • Paragkumar Thanki


Thermal yellowing and photobleaching are common problems that are seen to some extent in all automotive topcoat systems today. These effects can cause difficulties in the matching of light colors in the assembly plant and then later upon delivery to the customer. Current literature offers no clear mechanism for the thermal yellowing and photobleaching. Based on observed formulation dependencies, a mechanism is proposed based on oxidation of amine compounds. We constructed a model in vitro system using a hydroperoxide to thermally oxidize amines in solution. In this system, a series of amines were tested and both yellowing and photobleaching were reproduced. Loss of basicity confirmed that amine oxidation occurred under these conditions. Both the location of the UV absorption peak and strong amine structure dependence indicate nitrone formation as the yellow chromophore.


Thermal yellowing Photobleaching Amine oxidation 


  1. 1.
    Garland, RM, Elrod, MJ, Jimenez, JL, Tolbert, MA, “Acid-Catalyzed Reactions of Hexanal on Sulfuric Acid Particles: Identification of Reaction Products.” Atmos. Environ., 40 6863–6878 (2006)CrossRefGoogle Scholar
  2. 2.
    Scheirs, J, Long, TE, Modern Polyesters: Chemistry and Technology of Polyesters and Copolyesters, p. 62. John Wiley and Sons, West Sussex, UKGoogle Scholar
  3. 3.
    Templeman, C, “Yellowing in Automotive Clearcoats.” SAE World Congress 2016Google Scholar
  4. 4.
    Florio, M, Handbook of Coatings Additives, pp. 25–26. CRC Press, Boca Raton (2004)Google Scholar
  5. 5.
    Borland, JE, Chen, YDM, Sauer, JD, Smith, KR, Smith, RF, “Bleaching of Colored Amine Oxides.” US Patent 5,068,430Google Scholar
  6. 6.
    Sun, M, Hong, C, Pan, C, “A Unique Aliphatic Tertiary Amine Chromophore: Fluorescence, Polymer Structure, and Application in Cell Imaging.” J. Am. Chem. Soc. Commun., 134 20581–20584 (2012)CrossRefGoogle Scholar
  7. 7.
    Jai, D, Cao, L, Wang, D, Guo, X, Liang, H, Zao, F, Gu, Y, Wang, D, “Uncovering a Broad Class of Fluorescent amine-containing Compounds by Heat Treatment.” Chem. Commun., 50 11488 (2014)CrossRefGoogle Scholar
  8. 8.
    Chu, C, Imae, T, “Fluorescence Investigations of Oxygen-Doped Simple Amine Compared with Fluorescent PAMAM Dendrimer.” Macromol. Rapid Commun., 30 89–93 (2009)CrossRefGoogle Scholar
  9. 9.
    Riazy, M, Lougheed, M, Adomat, H, Tomlinson Guns, E, Eigendorf, G, Duronio, V, Steinbrecher, U, “Fluorescent Adducts Formed by Reaction of Oxidized Unsaturated Fatty Acids with Amines Increase Macrophage Viability.” Free Radic. Biol. Med., 51 1926–1936 (2011)CrossRefGoogle Scholar
  10. 10.
    Kochany, J, Lipczynska-Kochany, E, “Photochemistry of Some Alpha-(2-naphthyl) Nitrones.” J. Photochem. Photobiol. A Chem., 45 65–79 (1988)CrossRefGoogle Scholar
  11. 11.
    Kada, T, Obara, A, Wantanbe, T, Miyata, S, “Fabrication of Refractive Index Distributions in Polymer Using a Photochemical Reaction.” J. Appl. Phys., 87 (2) 638–642 (2000)CrossRefGoogle Scholar
  12. 12.
    Mielewski, DF, Bauer, DR, Gerlock, JL, “Determination of Hydroperoxide Concentrations in Crosslinked Polymer Coatings Containing Hindered Amine Light Stabilizers.” Polym. Degrad. Stab., 41 323–331 (1993)CrossRefGoogle Scholar
  13. 13.
    Gerlock, JL, Smith, CA, Cooper, VA, Dusbiber, TG, Weber, WH, “On the Use of Fourier Transform Infrared Spectroscopy to Assess the Weathering Performance of Isolated Clearcoats from Different Chemical Families.” Polym. Degrad. Stab., 62 225–234 (1998)CrossRefGoogle Scholar
  14. 14.
    Reproduced from J. Appl. Phys., 87(2) 638–642 (2000), with the permission of AIP PublishingGoogle Scholar
  15. 15.
    Cope, AC, Ciganek, E, “Methylenecyclohexane and N, N-Dimethylhydroxylamine Hydrochloride.” Org. Synth., 4 612 (1963)Google Scholar
  16. 16.
    Laughlin, RG, “Reversible Cycloelimination and Disproportionation Reactions in Aliphatic Amine Oxide-N, N,-Dimethylhydroxylamine-Olefin Systems.” J. Am. Chem. Soc., 95 (10) 3295–3299 (1973)CrossRefGoogle Scholar
  17. 17.
    Schnabel, W, “Thermolysis of Poly(Chloroethyl Methacrylates) and Poly(Chloroethyl Acrylates).” In: Clough, JR, et al. (eds.) Advances in Chemistry, Polymer Durability, pp. 33–45. American Chemical Society, Washington DC (1996)CrossRefGoogle Scholar
  18. 18.
    Bogner, G, Brunner, H, Hoehn, K, “Epoxy Resin Systems, which are Resistant to Aging, Moulding Materials, Components Produced Therefrom and the Use Thereof.” US Patent 7,183, 661, 2007Google Scholar

Copyright information

© American Coatings Association 2017

Authors and Affiliations

  1. 1.BASF Corporation, Automotive CoatingsSouthfieldUSA

Personalised recommendations