Automotive refinish coatings

Vehicle refinish (VR) coatings are used to repair damaged or corroded car paint systems. They must exhibit the same performance characteristics as the original paint system if they are to meet the car manufacturer s bodywork corrosion warranty. However, the most important feature of VR coatings is their colour. There are approximately 150 million cars on the roads of Europe, painted in over 20000 different colours, and every year a further 600 new colours are added. Paints also age and, depending on climatic conditions, a 10-year-old car may have changed colour considerably. A VR bodyshop must be able to match the colour of the car, irrespective of its age, colour and type of finish (which will usually be either a solid colour, metallic, or pearlescent). This is achieved by the skills of the VR bodyshop and the colour-matching system of the paint manufacturer. 

The painting process for VR differs from that used for new cars. While new car bodies can be heated at 120-140°C to cure the OEM paint system, a car for repair, complete with a tank of petrol, electronic equipment, rubber tyres and other heat-sensitive components, must be treated with care. Hence, cure temperatures of 60°C maximum are used for VR coatings. The solvent systems used must be capable of providing the necessary solubility, application, viscosity and flow characteristics. It must also evaporate quickly enough to enable the bodyshop to complete the repair as soon as possible, often under widely varying temperature and humidity conditions. 

During a repair, the damaged area is sanded down to bare metal and filled as necessary. An etch primer is often used to enable the VR coating to adhere to the surface of the metal. This is a very low solids coating which is applied at a low film thickness. Etch primers typically contain phosphoric acid and zinc chromate (although chromates are becoming unpopular for toxicity reasons), a binder (such as polyvinyl butyral) and a solvent system (usually based on ethanol, butanol and water). 

The primer surface hides minor imperfections and provides a smooth surface for topcoat application. These coatings have traditionally been polyester or epoxy based and used a combination of aromatic solvents 

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UV curing of automotive refinish coatings represents a powerful tool providing a fast curing process and improving the productivity of paint shops. The... 

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Recommended for products automotive refinish coatings, industrial topcoats, wood stains, radiation curable coatings ... 

Other important markets include automotive refinish coatings, maintenance coatings, aircraft finishes, camouflage coatings for military vehicles, wire enamels, magnetic tape, and coatings for plastics. 

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