Development of a Small-Sized Multilayer Fuel Tank for Motorcycles and ATVs Complying with EPA Gasoline Permeation Controls

As a result of recent EPA (U.S. Environmental Protection Agency) gasoline permeation control regulations, the fuel tanks on motorcycles and ATVs (All-Terrain Vehicles) are required to change to lower gasoline permeation performance on 2008 models. Therefore, we determined to use a multilayer plastic fuel tank. There are some molding issues that are peculiar to motorcycle and ATV fuel tanks. First, when the insert is blow molded, there is a reduction in welding strength. Second, peeling of the adhesion occurs on impact in the inserted parts. Third, saddle shapes with large ductility deformation are easy to be punctured during molding. Finally, the appearance of the fuel tank is not acceptable. In order to address the first issue, the welding performance, the drawdown of parison and the melting damage of insert parts were balanced, focusing attention to the temperatures of the parison and the insert. For the second issue, the adhesive strength was improved by enhancing the mallein anhydride value of the adhesive between layers. On the third issue, thickness control, using pre-blowing and a reduced pressure technique in the blow molding, was established. For the fourth issue, the surface texture of the mold die enabled the shortage of mold transfer to be concealed. These multilayered fuel tanks, which meet EPA plastic fuel tank permeation controls, have been adopted in almost all of the 2008 models of motorcycles and ATVs.