The scratch resistance of coatings used on two highly visible automotive applications (automotive bodies and window glazings) were examined and reviewed. Types of damage (scratch vs. mar), the impact on customers, and the causes of scratch events were investigated. Different exterior clearcoat technologies, including UV curable and self-healing formulations were reviewed, including results from nano- and macro-scratch tests. Polycarbonate hardcoat glazings were tested vs. annealed glass samples using a Taber abraser, with the resulting damage analyzed using transmitted haze measurements and optical profilometry. A correlation between the damage seen in glass samples (many smooth, shallow mars) and the best hardcoat samples (fewer, deeper scratches) and the haze measurements was discussed. Nano-scratch results showed similar fracture forces, but measurably improved mar resistance for the hardcoats/glass system compared to exterior clearcoats.
References
[1]
Courter, J.L. Mar resistance of automotive clearcoats: I. Relationship to coating mechanical properties. J. Coat. Tech. 1997, 69, 57–63.
[2]
Bertrand-Lambotte, P.; Loubet, J.L.; Verpy, C.; Pavan, S. Understanding of automotive clearcoats scratch resistance. Thin Solid Films 2002, 420–421, 281–286.
[3]
Courter, J.L.; Kamenetzky, E.A. Micro- and nano-indentation and scratching for evaluating the mar resistance of automotive clearcoats. Eur. Coat. J. 1999, 7–8, 24–38.
[4]
Lange, J.; Luise, A.; Hult, A. Influence of crosslink density, glass transition temperature and addition of pigment and wax on the scratch resistance of an epoxy coating. J. Coat. Tech. 1997, 69, 77–82.
[5]
Seubert, C.M.; Nichols, M.E. Scaling behavior in the scratching of automotive clearcoats. J. Coat. Tech. Res. 2007, 4, 21–30, doi:10.1007/s11998-007-9006-3.
[6]
Evans, D.C.; Lancaster, J.K. The wear of polymers. Treat. Mater. Sci. Tech. 1979, 13, 85–139.
[7]
Barna, E.; Bommer, B.; Kursteiner, J.; Vital, A.; Trzebiatowski, O.; Koch, W.; Schmid, B.; Graule, T. Innovative, scratch proof nanocomposites for clear coatings. Compos. Part A 2005, 36, 473–480, doi:10.1016/j.compositesa.2004.10.014.
[8]
PPG Patent U.S. Patent 6,387,519 B1, 14 May 2002.
[9]
Glasel, H.-J.; Bauer, F.; Ernst, H.; Findeisen, M.; Hartmann, E.; Langguth, H.; Mehnert, R.; Schubert, R. Preparation of scratch and abrasion resistant polymeric nanocomposites by monomer grafting onto nanoparticles, 2 Characterization of radiation-cured polymeric nanocomposites. Macro. Chem. Phys. 2000, 201, 2765–2770, doi:10.1002/1521-3935(20001201)201:18<2765::AID-MACP2765>3.0.CO;2-9.
[10]
Sepeur, S.; Kunze, N.; Werner, B.; Schmidt, H. UV curable hard coatings on plastic. Thin Solid Film 1999, 351, 216–219, doi:10.1016/S0040-6090(99)00339-9.
[11]
Seubert, C.M.; Nichols, M.E.; Cooper, V.A.; Gerlock, J.L. The long-term weathering behavior of UV curable clearcoats: I. Bulk chemical and physical analysis. Poly. Deg. Stab. 2003, 81, 103–115, doi:10.1016/S0141-3910(03)00079-X.
[12]
Yee, A.F.; Pearson, R.A. Toughening mechanisms in elastomer-modified epoxies: Part 1 Mechanical Studies. J. Mat. Sci. 1986, 21, 2462–2474, doi:10.1007/BF01114293.
[13]
Adamson, K.; Blackman, G.; Gregorovich, B.; Lin, L.; Matheson, R. Oligomers in the evolution of automotive clearcoats: Mechanical performance testing as a function of exposure. Prog. Org. Coat. 1997, 34, 64–74, doi:10.1016/S0300-9440(98)00022-8.
[14]
Ryntz, R.A.; Abell, B.D.; Pollano, G.M.; Nguyen, L.H.; Shen, W.C. Scratch resistance of model coating systems. J. Coat. Tech. 2000, 72, 47–53, doi:10.1007/BF02698019.
[15]
Nichols, M.E.; Darr, C.A.; Smith, C.A.; Thouless, M.D.; Fischer, E.R. Fracture energy of automotive clearcoats: I. Experimental methods and mechanics. Poly. Deg. Stab. 1998, 60, 291–299, doi:10.1016/S0141-3910(97)00081-5.
[16]
Evans, D.; Zuber, K.; Murphy, P. Ultrathin films of co-sputtered CrZrx alloys on polymeric substrates. Surf. Coat. 2012, 206, 3733–3738, doi:10.1016/j.surfcoat.2012.03.023.
[17]
Shi, X.; Croll, S.G. Thermal-induced recovery of small deformations and degradation defects on epoxy coating surface. J. Coat. Tech. Res. 2010, 7, 73–84, doi:10.1007/s11998-009-9176-2.
[18]
Seubert, C.; Nichols, M.; Henderson, K.; Mechtel, M.; Klimmasch, T.; Pohl, T. The effect of weathering and thermal treatment on the scratch recovery characteristics of clearcoats. J. Coat. Tech. Res. 2010, 7, 159–166, doi:10.1007/s11998-009-9190-4.
Gilliam, M.A.; Gasworth, S. Characterization of the Parameter Space in Expanding Thermal Plasma Systems with Organosiloxane and Oxygen Reagents. In Proceedings of Society of Vacuum Coaters Annual Conference, Chicago, IL, USA, 19–24 April 2008.
[22]
Federal Motor Vehicle Safety Standard 205; US Department of Transportation: Washington, DC, USA, 2006.
[23]
Abrasion Resistance; American National Standard for Safety Glazing Materials for Glazing Motor Vehicles and Motor Vehicle Equipment Operating on Land Highways—Safety Standard, Tests 17 and 18; SAE: Warrendale, PA, USA, 1997.
[24]
Taber Abraser (Abrader). Available online: http://www.taberindustries.com/taber-rotary-abraser (accessed on 24 August 2012).
[25]
ISO 20566: 2005, Paints and Varnishes—Determination of the Scratch Resistance of a Coating System Using a Laboratory Car-Wash; ISO: Geneva, Switzerland, 2005.
[26]
Sikder, A.K.; Babbie Paul, N.; Shuler, S.; Gilliam, M.; Dinesh, K.; Parthipan, B. Polycarbonate Glazing—Accelerated Wiper Testing, Surface Characterization and Comparison with On-Road Fleet Data; SAE Technical Paper; 2012–01–0750; Detroit, USA, 2012.
[27]
Uniform Provisions Concerning the Approval of Protective Helmets and Their Visors for Drivers and Passengers of Motor Cycle and Mopeds; Annex 10—Abrasion Test; ECE Regulation No. 22; UNECE: Geneva, Switzerland, 2002.
