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Self-Healing Paint Technology in Automotive Applications

BY IAN STEELE. Over the last 20years or so there have been continual major developments in the automotive industry; in terms of performance, technology and aesthetics. From breaking world land speed records, to introducing increased safety measures and road-worthy electric vehicles, the latest innovation in the automotive industry is always just around the corner. Advancements in technology play a major role in these improvements and are largely responsible for frequently changing the standards and expectations we have for our cars.

As innovative and beneficial as these technological enhancements may be, they nearly always seem to focus on the actual machinery or the interior of the car. Engines and machinery aside, the majority of all other automotive advancements happen within the inside of a vehicle. Electric controls for windows and mirrors, Bluetooth stereo systems, cruise control, satellite navigation and climate control are just a few examples of general technological improvements for the interior of modern-day vehicles. So, why isn’t the automotive industry placing as much focus on developing technology for the exteriors of our cars? It sounds strange, but there is a wealth of benefits we can gain from technical improvements to something as small and simple as our car’s paint job.

Additional Benefits – Paint that Cleans Itself
These days, it’s possible to coat almost anything in a durable finish, no matter if it’s thousands of feet in the air or deep below sea level. So if we are able to coat anything in this wonderful material, it makes sense to try and obtain some additional benefits from it, other than aesthetic appeal. For example, Nano Labs in Detroit, Mich., have miraculously invented a paint that cleans itself. Nanoparticle technology is integrated within the paint’s molecular structure, which allows it to degrade dirt particles. Pollutants are broke down using nothing but natural light, meaning surfaces appear to clean themselves. How much money and/or water would this save us all in car washes alone? This is by no means the most exciting advancement in paint technology, but one that should still be considered for commercial use, no doubt.

Self-Healing Paintwork
There are few feelings more sinking than those experiences when you scratch the finish on a brand new car — aside from those felt when you pay for the repair. Scratching your car can be expensive and rather annoying to say the least; so imagine a car that can repair itself when scratched. Marek Urban, polymer science and engineering professor, along with his Urban Research Group at The University of Southern Mississippi have done just that — develop a type of paint that can heal itself with nothing but natural light. With industrial spray solutions in mind, this development could make a huge difference to the vehicle market of today.

This polymeric coating incorporates an oxetane-substituted chitosan precursor integrated into a two-component polyurethane.[1] When damaged, ultraviolet light splits the molecules, which then spread out to cover and heal the blemish automatically. Chitosan is plentiful and very cheap as it is extracted from the primary component of the exoskeletons of lobsters, crabs, shrimps and other crustaceans. So if your car picks up a knock or a scratch on the way to work, you can rest assured it will be fixed by the time you arrive home!
The Science – How Does it Work?
When the paintwork is scratched or damaged, the material splits and the four-member oxetane rings open to create two reactive ends. With the introduction of UV light chain scission occurs in the chitosan, which cross-links with the reactive ends of the oxetane and thus repairs the molecular network. The Urban Research Group believes that a small scratch will heal in less than 30 minutes.[2] Sunlight is the ideal trigger, so any time your car needs a re-spray, just take it out for a drive!

The whole process is not subject to conditions such as moisture or temperature, so it will work at all times. It is also fairly inexpensive, making it extremely economical for the automotive industry. The only drawback is that this repairing action only happens once, so each part of the coating has one shot only. But the chances of hitting the exact same spot, within microns distance, are extremely small.
Has it Been Done Before?
In short, yes, it has been tried before — but not as successfully. In 2005, Nissan introduced ‘Scratch Guard’ paint to a number of their models, which contained a high elastic resin that prevented scratches from damaging the inner layers of a car’s paintjob.[3] Although the product is very similar to that created by the Urban Research Group, the way that it works is slightly different. Repair times varied from anywhere between a day and a week and was only effective for three years maximum; results also depend on weather conditions and temperature.

The Future in the Automotive Industry
Despite scratch-proof paint not taking off with Nissan, the future of scratch-free cars looks bright with this latest development of the Chitosan compound. Having the ability to rapidly repair a scratch on your car, no matter the conditions or age of the car, is surely a major advancement for the industry as a whole. The financial benefits are huge, as scratch-proof cars could potentially lower maintenance costs and insurance premiums, too. At the time of this writing, there are no car manufacturers currently in the UK who are publicising any research into the use of polyurethane paint. Let’s hope they are just trying to keep it secret and we start seeing scratch-free cars on the market someday soon!
Ian Steele is a technical writer and active follower of paint technology and innovation. He has happily filled the role of editorial coordinator at Industrial Spray Solutions for the last year and his other areas of interest include science, travelling and the automotive industry. You can reach Ian via e-mail or via the address below:
Industrial Spray Solutions
Unit 1
Saxon Street Works
Saxon Street
M24 2AD


Posted 31/10/2013 by Reg Tucker

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