Polyolefins are a group of plastics formed by the polymerization of olefin monomer units. The most common polyolefins are polypropylene (PP) and polyethylene (PE). Subgroups of these are high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polypropylene (PP). HDPE is commonly used for fuel tanks, bottle caps and plastic bottles. LDPE is used for liquid containers, tubing and plastic wrap (eg plastic milk jugs). PP is used for piping, carpet, roofing, hinges and auto parts. Polyolefins have excellent chemical resistance and are unaffected by common solvents, but this also means they have poor adhesion properties to both paints and adhesives.
We have done qualitative testing and have determined that you can improve adhesion by sanding the surface first, then priming with our Primer for Acrylic Enamel
then top coating with our Hedrix fast dry spray paint (orderable from any color page).
We would still recommend testing this yourself to make sure it meets your specific requirements. The adhesion may be improved further by using an adhesion promoter like "Bulldog" in place of the primer. This is commonly used in automotive applications where the painting is done over polymetric panels like Polypropylene.