Tanaka, A., Inoue, T., Mochizuki, S., and Inoue, M., "Development of Waterborne Conductive Primer for Motorcycles," SAE Int. J. Mater. Manf. 6(1):113-123, 2013, doi:10.4271/2012-32-0089.
Most types of paint materials currently used for motorcycles contain large amounts of VOCs (Volatile Organic Compounds). VOCs are environmental load substances, and there is a demand to reduce emissions in recent years. Many of a motorcycle's exterior parts are made of ABS (Acrylonitrile-Butadiene-Styrene) plastics (henceforth ABS) or PA (Polyamid) plastics (henceforth PA). These two plastic materials have different film adhesion mechanisms and adhesion strength. Therefore it was necessary to use different conductive primers and that's was one of the factors which made time and material losses in the painting processes. We solved those two issues, the reduction of VOCs and the common use of the same conductive primer for different parts materials, by combining two kinds of resins originally designed as the conductive primers, i.e., urethane resins with carboxylic acid groups and acrylic resins with amide groups, which are different in properties. Many of the plastic parts used in motorcycles are painted manually because there are difficult portions to be painted by automated painting machines. The viscosity was adjusted to satisfy both the controllability of paint sagging and the surface smoothness to keep the efficiency of paint workers' operations.