Multi-layer Tanks

Most rotational molded products are mono-layer solutions, but multi-layer solutions can enhance performance. When making fuel tanks or fuel reservoirs from rotomolding resins, there are performance requirements that regulate the allowable fuel emissions from the tanks. The EPA fuel permeation regulations are a federal set of regulations for manufacturers of fuel tanks that must be followed, to regulate fuel permeation. Fuel permeation refers to evaporation of fuel from the tanks. There are also state regulations like those from California described as the CARB fuel permeation regulations, which are more stringent in some cases and cover a wider range of applications.

Crosslink resin on its own does not have a low enough fuel permeation rate; but it has excellent mechanical properties to ensure tanks meet other performance requirements for their final application, such as impact strength. As a result, multi-layer barrier tanks are made by having polyamide powder molded as an inner barrier layer in the tanks. Polyamide is either added through drop-box technology or by briefly removing the part from the oven after forming the XLPE layer to load polyamide before transitioning back to the oven. Ingenia Superlink® has excellent adhesion to the polyamide resin and works well in multi-layer barrier applications.