Automotive Coatings
Automotive coatings performance test and substrate types
Auto components are composed of metallic and non metallic substrates. Being low in surface energy, the plastic parts are difficult to adhere with paints. A high level of research is needed to have a durable adhesion over plastic surfaces. Any coating material which needs to be applied at OEM level needs many long term performance testing including – cyclic corrosion resistance [ASTM B117], Abrasion resistance [ASTM D4060], Cross hatch adhesion [ASTM D3359] and cyclic humidity resistance [ASTM D2247] etc.
Common substrate in automotive coatings:
- ABS
Commonly abbreviated for Acrylonitrile Butadiene Styrene, ABS is an opaque thermoplastic and also an amorphous polymer widely used in automotive applications. “Thermoplastic” refers to the material which when heated can be transformed in their physical state but on cooling comes back to their original state.
Thermoplastics materials have a “glass transition” temperature at which (105 degrees Celsius in the case of ABS) material changes their state from solid to liquid. They can be heated to their melting point, cooled, and re-heated again without changes in their chemical nature or any degradation.
Unlike thermosets, instead of burning, thermoplastics [eg. ABS gets liquified], which allows them to be easily injection molded.
2. Polycarbonate [PC]
Like ABS, polycarbonates (PC) are also thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates can be used standalone for automotive parts or can be blended with ABS to enhance properties. These are engineering plastics which are very strong, tough and transparent. They are easily moulded to required shape and size during the injection moulding process.
3. Nylon
Nylon plastics are also called polyamides (PA) which are classified based on the number of carbon present in the polyamide repetitive chain viz. Nylon 6, Nylon 6,6 and Nylon 6,12 etc. It is a synthetic thermoplastic polymer very commonly moulded by injection molding process and widely used in automotive applications. It’s a versatile, durable, flexible material often used to as an economical alternative to many other material needed for high durable articles.
Advantages of nylon include:
- High melting point their by better dimensional stability.
- Low surface energy and frictional force.
- High tensile strength
- Resistance to various chemicals
- High abrasions resistance
- High weather resistance.
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