Thermoplastic olefin (TPO) materials belong to the larger group of thermoplastic elastomers (TPEs). As such, they come in many formulations and can be molded into parts with different surface finishes. Increasingly used in the automotive industry as an alternative to high-cost, heavy metal materials, TPO plastics present unique bonding challenges for pressure-sensitive adhesive (PSA) manufacturers.
TPOs fall into the category of low-surface-energy (LSE) materials. Pressure-sensitive materials generally have a lower affinity for LSE surfaces than, for example, materials like stainless steel or glass. Over time, oils present in the TPO may migrate to the surface and interfere with the adhesive bond. TPOs are selected by auto manufacturers in part due to their resistance to elements such as chemicals, UV, high/low temperatures, and oils that a vehicle will be exposed to over the course of its service. In addition, TPOs are impact resistant and highly moldable to create the shapes and custom pieces needed for today’s automotive interior designs. Adhesives must be formulated to not only bond to this challenging material, but also to withstand the same operating conditions as the TPO.