Real World Performance of Painted Plastic Components

By Rose A. Ryntz

The automotive industry the largest manufacturing industry in the world. Over 70 separate companies employ more than four million people. At current build rates of 17 million units annually, there are estimated to be over 350 million operable vehicles on the earth today. While steel still accounts for approximately 90% of the weight of a vehicle, plastic usage continues to increase due to styling latitude, cost and weight savings, and low temperature impact performance.

Of the nearly two billion pounds of plastics utilized in automotive applications, approximately 30% of plastic components are painted. For the painted applications, performance attributes are governed by the environment to which the component is exposed, e.g., interior versus exterior. Key attributes that must be attained in painted plastic applications, irrespective of the environment, include adhesion and abrasion resistance. Additional performance requirements attributed to exterior environments include chip and “gouge” resistance.

Gouge resistance is defined as the cohesive behavior of a painted plastic when exposed to compressive shear events, e.g., a shopping cart hitting a painted bumper in a parking lot, a low speed impact between two vehicles’ bumpers, and the like. All of these performance behaviors are linked to some property or properties of the plastic, the paint, or the paint/plastic interface, but little has been done to understand the influence of processing parameters on the performance of the painted plastic composite.