Investigation into the release of microplastics and metallic ions into the environment during the long-term degradation of pre-painted metals

Introduction:

The European Commission, as part of their Green Deal, are investigating the generation (intentional or not) of microplastics and chemical species from products during their service life. The European Coil Coating Association (ECCA) is sponsoring an investigation into the formation of microplastics from the organic coating and the release ("run-off") of chemical species during the long-term degradation of prepainted metals.

Given the durability of prepainted metals (>40-years), it is important to establish the extent (if any) of microplastic and other particulate formation from the coated product over this period. Whilst there is no current regulation related to these issues, it is conceivable that future legislation may require abatement measures to prevent release of both microplastics and metallic ions.

Objective and scope of the study:

The primary objective of the work is to identify the main mechanisms for microplastic and other particulate formation during the degradation of the prepainted metal product through:

1. The use of advanced analytical techniques such as UV, ATR FTIR, SEM and particle sizing to determine the mechanism and rates of major coating degradation e.g. mechanical, UV and to understand the nature of the organic and inorganic particulates released through erosion.

2. Understanding how representative climatic conditions affect the rates of erosion and changes in coating characteristics using through depth profiling and surface analysis techniques. 3. Detailed investigation of the run-off material released from the coated samples.

4. Correlation of accelerated testing results with naturally weathered material with particular focus on the types and quantity of environmental release. 5. Quantification of the total yearly releases from outdoor prepainted metal exposure, over the whole of the EU. The experimental design will include an appropriate number and combination of the following systems:

(a) Polyester, polyurethane, PVDF and plastisol coated metal. (b) Zinc-coated steel and aluminium substrates. (c) "Model" organic coatings which will rapidly degrade and release chemical components e.g. polyamide beads. The proposed scope of work could also be extended, where appropriate, to include such topics as:

(i) Determining the fate of the released species in the environment e.g. locations for bioaccumulation. (ii) Further degradation mechanisms once released into the environment. (iii) Impact of the released species on the environment e.g. evidence for biotoxicity. Predicted Outcomes:

The project will provide an understanding for the potential release of organic material and metallic ions into the environment. This may enable ECCA members to formulate improved organic coatings with reduced environmental impact which will maintain the competitive position of the products in the European market.