BASF has developed iGloss, an innovative product that strikes a balance between soft and hard clearcoat formulations for automotive applications. The end result, according to the company, is a glossy appearance that will last significantly longer than conventional coatings.
“Over the course of five years of research and development, we have succeeded in combining the advantages of hard inorganic and soft organic materials,” said chemist Dr. Matthijs Groenewolt, who is responsible for developing iGloss at BASF. “This hybrid structure allows us to achieve a high level of long-lasting scratch resistance. In addition, iGloss is significantly more weather-resistant and more flexible than other highly cross-linked clearcoat systems.”
How it works: The special nanostructure of the iGloss coating does not form until the paint—with the addition of a hardener together with a catalyst—is baked on the surface of the car at a temperature of around 140 degrees Celsius. If needed, the lattice structure can also be formed at lower temperatures if the right catalyst system is selected.
The color and gloss of an automotive finish play a major role in a potential car buyer’s decision. Estimates suggest that one out of four car buyers is prepared to switch car makes due to a particularly attractive finish. However, even the prettiest finish suffers from the many external impacts to which it is subjected over its lifetime. They include climatic influences such as sun, rain, snow and temperature fluctuations, as well as road salt, sap and bird droppings, all of which attack the paintwork. Other nuisances include the tiny scratches on the surface primarily caused in the car wash by the brushes and dirt on the car body. If the scratches multiply over time, the automotive finish can look dull and unattractive. The job of the clearcoat, the uppermost of the four layers of an automotive finish, is to offer protection from this mechanical wear and from climatic influences. In order for the clearcoat to fulfill its protective function, it must not be too hard or too soft. If the finish is too hard, it won’t offer sufficient weathering resistance, and it will become brittle and quickly flake off. On the other hand, if it is too soft, it mostly stops protecting the finish from microscratches and chemicals such as fuels, which might wet the coating during refueling.
According to BASF’s research, previous standard clearcoats for cars have consisted almost exclusively of organic material, referred to as polymers, which are long-chain branched hydrocarbons. In contrast, iGloss combines two kinds of materials in a nanostructured hybrid. Between 90 and 95% of the hybrid material, depending on the area of application, consists of organic material which forms the paint matrix. This makes the finish flexible and elastic and ensures a high level of weathering resistance. Five to 10% of the inorganic material is embedded in the organic matrix. These silicate nanoclusters are particularly hard and scratch resistant. They consist of a small number of atoms and are distributed throughout the coating homogeneously and densely. The organic and inorganic components are covalently and thus elastically bonded. This allows the clearcoat to immediately spring back to around 90%, for instance, when hit by the bristles of a car wash brush. This is what many paint experts refer to as “elastic recovery” or “instant reflow.” Conventional clearcoats only attain reflow rates of approximately 70%. With the new BASF clearcoat, the microscratches that occur are significantly flatter and therefore less visible.
But there’s more to the innovative clearcoat than scratch resistance. According to BASF, it also offers superior weather resistance—meaning the ability to withstand sun, rain and fluctuations in temperature. A lab test under extreme conditions with both very high temperatures and high radiation intensity showed the difference between iGloss and conventional clearcoats. Even after 4,500 hours, the new clearcoat retained most of its gloss. In contrast, other clearcoats became dull and showed cracks during this unusual stress test. (The types of wear vary to which a clearcoat is exposed during weathering.) While UV radiation emitted by the sun causes the formation of radicals and may degrade the polymer paint matrix, fluctuations in temperature lead to tensions in the material. Practical tests under everyday conditions with subsequent scratch tests confirmed the lab results: For surfaces finished with the BASF clearcoat, the gloss remains for about twice as long as with conventional clearcoats. That is good news for all car owners, not just because vehicles retain their new appearance for longer, but also because iGloss allows cars to maintain their value longer.
The good news for applicators is the clearcoat can be applied with the existing paint lines without requiring any major changes. This was confirmed by successful test runs at several automakers, according to BASF. After favorable results during pilot tests, it has been used in mass production since mid-2011. Daimler is the first carmaker worldwide to use it, coating several models at its Bremen plant, including its Mercedes SLK. BASF reports that other major car manufacturers have expressed a great deal of interest in iGloss as well.
For more information, please visit www.basf.com.