Recent Developments in Two Component Urethane Coatings for Automotive Plastics: The Relationship Between the Mechanical Properties of Coating and Substrate

The coating of plastic substrates, particularly for applications in impact-prone areas of an automobile, requires the coatings technologist to be aware not only of the mechanical properties of the substrate which is to be coated but also of those of the coating, and of the coating/substrate interaction. It is a widely accepted observation that coating a flexible substrate with a relatively rigid paint system will cause premature impact failure of the substrate. This paper provides a detailed examination of the relationship between coating flexibility and substrate impact resistance and offers guidelines to overcome premature impact failure by the use of variably flexible two component urethane paint systems.