Bayer MaterialScience LLC has developed new polyurethane raw materials that can be used to formulate self-healing coatings.

These new developments were the topic of a technical presentation, “Self-Healing Polyurethane Clearcoats — New Developments for Exterior Automotive Coatings,” given by Karen Henderson, senior associate scientist, Bayer MaterialScience LLC, and Christopher Seubert, Ford Motor Company, at the 33rd Annual FOCUS (Future of Coatings Under Study) Conference. Sponsored by the Detroit Society for Coatings Technology, the conference was an educational event for coatings formulators, manufacturers, end users, raw material and equipment suppliers, educators and students. The theme for this year’s conference, which took place May 1 at the MSU Management Center in Troy, MI, was “Transformation in Transportation Coatings.”

Henderson and Seubert explained the customer and market requirements that are driving forces in the coatings market. These include the desire for coatings that are durable (scratch and chemical resistant), fast curing, and meet volatile organic compound (VOC) regulations, such as high-solids and waterborne coatings.

The presentation addressed the theory behind self-healing polyurethane coatings. According to the authors, two-component polyurethane coatings are inherently self-healing due to their unique chemistry and offer a number of intrinsic advantages that address customer and market requirements. These advantages include:

• High reactivity and full crosslinking, even at low-temperature curing
• Good chemical resistance and weather stability
• Hardness, toughness and elasticity due to urethane and urea structure
• Hydrogen bonds that allow for thermoplastic flow to relieve stress and allow self-healing of defects
• Basecoat compatibility
• High solids/low VOC
• Pleasing optical properties (a high gloss or “wet look”)

During the presentation, Henderson and Seubert also reviewed the results of laboratory macro-scratch tests demonstrating the properties of this technology. According to the authors, Ford laboratory macro-scratch/profilometry testing showed that the polyurethane system showed more scratch depth recovery versus the control OEM clearcoat. Furthermore, the nanoscratch method showed that the polyurethane system takes three-times more force to fracture than the control OEM clearcoat.

“The benefits of self-healing polyurethane coatings have been demonstrated on examples of automotive refinish, OEM and plastics clearcoats,” concludes Henderson. “At BMS, we believe this is a promising technology that will continue to gain momentum.”

For more information, visit www.bayermaterialsciencenafta.com.