The overall world automotive paints and coatings market was estimated to be worth more than $8 billion in 2013 and nanomaterials will play a role in future growth, as longevity of components via protective surfaces is a key market driver.
Market drivers
Coating technology is a key area in the automotive market, for protection from:
• UV
• wear
• heat.
Promotion of adhesion and reduction of engine friction are also key areas. Nanocoatings have proven to enhance the life and wear resistance of automotive parts.
The basic trends that nanomaterials enable for the automotive sector are:
• lighter but stronger materials (leading to improved fuel consumption and increased safety);
• improved engine efficiency and fuel consumption (catalysts; fuel additives; lubricants);
• reduced environmental impact from nanomaterial-enabled hydrogen and fuel cell-powered cars;
• improved and miniaturized electronic systems;
• better economies (longer component life; lower component failure rate; smart coatings for self-repair).
Performance benefits
Many automotive parts have a protective coating applied to improve the appearance or provide additional durability to the substrate which can be further enhanced by the incorporation of nanomaterials. Coatings containing nanoscale carbides, nitrides, metals or ceramics improve the performance of internal mechanical components of a vehicle, such as the engine. Desirable functional properties for the automotive coatings industry afforded by nanomaterials include:
• Scratch resistance (alumina, silica nanoparticles, nanozirconia);
• Anti-fingerprint;
• Self-cleaning (Nano-Tio2, nanosilica);
• Chemical resistance;
• UV resistance (zinc oxide, cerium oxide, titanium oxide, iron oxide nanoparticles);
• Abrasion resistance (alumina, silica nanoparticles, nanozirconia).
By reducing wear and friction, nanocoatings increase the lifetime of the working material at the same time that they reduce the dissipation of energy as heat, thus increasing the efficiency of the vehicle.
Nanocoatings offer improved solvent, fuel and gas barriers, and have heightened flame resistance, stiffness, and other mechanical properties. These coatings can increase productivity (longer component life, higher cycle frequencies, less work piece finishing), reduce manufacturing costs, improve the quality of products (due to smoother surfaces, better dimensional stability, higher degrees of metal deformation and fewer manufacturing steps), and reduce lubricant consumption.
Commercialization
Main applications of nanocoatings in the automotive industry at present are for oxide scale protection and easy-clean/anti-fogging coatings for automotive glass. Volkswagen, BMW, Toyota and Subaru utilize nanocoatings for this purpose. Mercedes-Benz incorporate scratch-resistant nanocoatings in some models. These nanoparticle clearcoats display significantly greater external protection and enhanced paint gloss compared to vehicles with conventional paintwork.
Anti-scratch: Consumers desire a permanent, scratch-free finish on all parts of automobiles, and scratch performance is the highest rated customer concern for automotive paint systems and displays. Nanocoatings can provide protection against scratches caused by, for example, mechanical car-washes, ensuring visibly enhanced gloss over an extended period of time.
Nanoparticles such as Al2O3, SiO2, ZrO2 and TiO2 have been incorporated into scratch resistance coatings that have been applied as automotive finishes to increase surface hardness and resistance to indentation. Bayer and Nissan (Scratch Guard Coat) have produced nanocoatings for improving the scratch/mar resistance of clearcoats.
Anti-fogging: UV-curable, highly crosslinked polymer coating systems containing both hydrophobic and hydrophilic nanodomains are utilized in anti-fogging coatings. Surfaces coated are capable of spreading water and thus preventing fog formation on a variety of optical substrates such as automotive plastic and glass, including the headlamp covers of automobiles. Hydrophobic and oleophic glass allows for greatly improved visibility in the rain, and reduces the adherence of dirt and contaminants to a treated surface.
Engine: Coatings play a crucial role in an automobile engine for lubrication (reduced frictional loss), thermal insulation (higher operating temperature), and reduced friction. Use of nanocoatings can lead to a significant increase in engine performance, thereby decreasing fuel consumption and increasing the exhaust gas temperature. Nanocoatings display improved thermal resistance and reduced thermal conductivity compared to coarse grained coatings.
Anti-fingerprint: There is a high demand in the automotive industry for clean surfaces that present a perfect, hygienic optical appearance that is insensitive to fingerprints, especially with the increasing incorporation of touch panel displays.
UV protection: Automotive coatings are required to be highly resistant against weathering from UV and other environmental factors. To enhance coating resistance against sunlight, HALS (hindered amine light stabilizer) and/or organic UV-absorbers has been added to clearcoat formulations.
