Chlorinated polyolefin (CPO) adhesion promoters for polyolefins

Tramaco Trapylen adhesion promoters bond paints, inks, and adhesives to polypropylene, polyethylene, and TPO. Solid, solvent-borne, waterborne, and UV-curable forms.

Home Products Coatings additives CPO adhesion promoters

The polyolefin adhesion problem

Polypropylene, polyethylene, and TPO are low-surface-energy plastics. Their surfaces are non-polar, so paints, inks, and adhesives have nothing to grip and will not bond to them on their own. A coating that looks fine when it goes on can peel, flake, or fail a tape test in service.

The usual fix is physical surface treatment: flame or corona pre-treatment to oxidize the surface before coating. That works, but it adds a process step, equipment, and a treatment window that has to be managed before the surface relaxes again.

How a CPO adhesion promoter works

A chlorinated polyolefin adhesion promoter does the same job chemically. The workhorse Trapylen grades are maleic-anhydride-grafted chlorinated polypropylene. The chlorinated polyolefin backbone is compatible with the untreated polyolefin surface and anchors into it, while the polar maleic-anhydride-grafted groups give the next layer something to bond to.

Applied as a thin tie-coat or blended into the coating or ink itself, the promoter becomes the bridge between the plastic and the topcoat, ink, or adhesive. Bond strength comes up, tape-test and peel failures come down, and in many cases the flame or corona step can be reduced or removed.

Matching the form to the system

Trapylen comes in four carrier forms so the promoter fits the system it goes into. Choose the form to match the coating or ink, then we narrow the grade to the substrate and the bond you need.

Solid resin

Neat polymer that the formulator dissolves into the carrier of their choice.

Solvent-borne solution

Ready-made solutions for solvent coatings, inks, and primers.

Waterborne dispersion

Aqueous dispersions for waterborne and low-VOC systems.

UV-curable

Polymer carried in a reactive acrylate monomer for energy-cure inks and coatings, with no solvent.

Where CPO adhesion promoters are used

  • Flexible-packaging inks printed on BOPP, PP, and PE film, with the promoter blended into the ink
  • Automotive plastic parts on PP and TPO, such as bumpers, claddings, and trim, as a primer before paint
  • Industrial and appliance coating of molded polyolefin parts
  • Adhesives and laminating systems that have to bond to polyolefin surfaces
  • UV screen and flexo inks on plastic substrates

If you run PP, PE, or TPO substrates and you are seeing paint, ink, or adhesive peel or tape-test failures, or you are told the part needs flame or corona treatment, that is a CPO adhesion-promoter application. Read more in how chlorinated polyolefin adhesion promoters bond coatings to polyolefins.

Frequently asked questions

What substrates need a CPO adhesion promoter?

Low-surface-energy polyolefins, mainly polypropylene, polyethylene, and TPO. These plastics resist bonding by paints, inks, and adhesives, and a chlorinated-polyolefin promoter gives the coating a surface it can grip.

Can a CPO adhesion promoter replace flame or corona treatment?

In many applications it can reduce or remove the physical pre-treatment step, because the promoter provides the polar bonding surface chemically. Whether it fully replaces treatment depends on the substrate and the coating, so trial it on the real part. Samples are available on request.

Which form should I use?

Match the carrier to your system: solvent solution for solvent coatings and inks, waterborne dispersion for low-VOC systems, UV-curable for energy-cure inks, or solid resin if you prefer to dissolve it into your own carrier. Tell us your system and we will narrow the grade.

Bonding to a polyolefin?

Tell us the substrate, the coating or ink it has to hold, and the carrier you want. We will recommend a grade and send a sample so you can run it on the actual part.