The industrial use of plastics has been favoured due to the lightweight, low density, flexible, strong, and low-cost properties. However, a metallic coating on the plastic surface is required to enhance their wear and corrosion resistance, as well as their aesthetic appearance. Since most plastics are non-conductive material, a series of intermediate steps is required to allow the metal coating deposition:
Pre-treatment step 1: Surface Etching to enhance metal adhesion. Current processes use chromic (Cr6+) acid bath solutions, despite the occupational safety and environmental risks.
Pre-treatment step 2: Surface Activation to disperse nucleation sites to ensure electroless metal deposition. Current processes employ Sn-Pd baths, even though Pd is a critical raw material.
Metallization via electroless plating, where a thin metal film is initially deposited on the surface. Now the plastic surface is conductive to proceed with electrodeposition of metals.
Plating on Plastics will deposit the metallic coating on the plastic surface.
The FreeMe project aims to eliminate the use of hexavalent chromium (Cr6+) and palladium (Pd) from the Plating on Plastics (PoP) process, based on REACH compliant chemicals, avoiding toxic compounds and ensuring long-term sustainability. For this purpose, FreeMe proposes two safe and sustainable by design approaches for the metallization of polymeric surfaces:
- Utilization of sprayable resins with the addition of suitable nickel-based precursors, that will be deposited on the plastic surface leading to the creation of the necessary nuclei for the next step of electroless deposition and the formation of the conductive layer.
- A Cr6+ & Pd free pre-treatment of the surface followed by incorporation of nickel active sites via reduction of nickel salts in the plastic surface. The electroless plating of the surface will follow leading to the formation of the conductive layer.
The proposed technologies will be applied in three different applications in the:
- aerospace and
- home appliances industries