The Shift from PFAS Plastics to Nano Coatings in Packagin

The Shift from PFAS Plastics to Nano Coatings in Packaging: The Impact of the European Single-Use Plastic Directive

The introduction of the European Single-Use Plastic Directive 2019/904 (SUP Directive) has brought a new perspective on the use of single-use plastics. This directive aims to promote circular approaches, prioritizing sustainable, non-toxic reusable products and systems for reuse over single-use items. Consequently, many companies are focusing on replacing plastic with alternative materials. However, this shift has led to some unintended consequences. For example, coffee cups treated with water dispersion are marketed as ‘plastic-free,’ despite containing synthetic materials that fall under the SUP regulations.

To address these issues and prevent the circumvention of the SUP regulations, the Ministry of Infrastructure and Water Management (the Ministry) sought further insights into these matters. This exploratory research aims to answer several key questions posed by the Ministry regarding coatings and barriers in paper and other natural fiber products.

1.1 Exploratory Questions

The research aims to answer the following questions:

What types of coatings and barriers are available to make cups and food packaging made from paper or other natural fibers water- and grease-resistant? (Chapter 3)
How do these coatings fit into the recycling chain/waste processing of packaging? What is the effect of water dispersion on waste processing? (Chapter 6)
How does water dispersion work? (Chapter 3)
What is the difference between water dispersion and standard plastic coatings? (Chapter 4)
What materials are suitable to function as packaging for beverages and hot meals without polymers, and what is their waste processing route? (Chapter 5)
Are there organizations that issue a ‘plastic-free’ certificate (e.g., in Germany)? What standards are used for this certification? Are there other organizations that do this? (Chapter 7)

Each question will be addressed in a separate chapter.

Conclusion: The Definition of Plastic

There is a fundamental difference between products that are completely free from synthetic polymers and can be labeled as "plastic-free" and products that fall outside the scope of the SUP Directive.

Products listed in the appendices of the SUP Directive and made from materials without synthetic polymers (such as wood, glass, metal without coatings, cotton, jute, bamboo, wood pulp, or bagasse pulp without additives or coatings) fall outside the scope of the SUP Directive and can be considered "plastic-free."

Conversely, similar products that contain synthetic polymers excluded by the SUP Directive (such as printed and treated cardboard and paper products) cannot technically be called "plastic-free," but they do fall outside the scope of the SUP Directive. Examples include paper straws. The diagram below illustrates the relationship between these terms.

Coatings and Barriers for Natural Fiber Materials

There are many different methods to make cups and other packaging made from paper and natural fibers water- and/or grease-resistant. These can be categorized as follows:

3.1 Physical Coatings and Laminates

A common method is to apply a plastic layer as a barrier. Paper inherently lacks water- or grease-resistance. Cardboard drink cups and food packaging are often coated using extrusion coating, where molten plastic is applied as a thin film on the paper or cardboard. The plastic coating is then cooled with large rollers, allowing the paper or cardboard to be rolled up again.

Common plastic extrusion coatings for paper and cardboard include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polylactic acid (PLA). Multi-layer extrusion coatings with barriers such as EVOH or nylon are also possible for food packaging but are less common for simple takeaway packaging or cardboard drink cups. The coating thickness varies based on the desired barrier, application, and material, usually specified in grams per square meter (gsm). Cardboard drink cups typically have a single-sided PE coating with thicknesses ranging from 15 to 20 gsm, while the bottom often has a coating on both sides, ranging from 12-18 gsm. A smaller portion of the cardboard drink cups on the market features a PLA extrusion coating, typically between 30 and 35 gsm. Compared to PE-coated packaging, PLA-coated packaging requires more plastic for the same functionality.

Alternatively, a plastic layer can be applied using a laminating process, where a plastic film is glued onto the paper or cardboard. This method is sometimes used, for example, if the cardboard is first printed and then a plastic film is applied, or to combine different materials and types, such as paper, aluminum, and plastic.

3.2 Chemical Treatments of Paper, Cardboard, and Pulp

Another approach to making packaging resistant to water and grease is by adding certain substances during the production of paper and pulp products. These additives, known as sizing agents, are used to make paper and pulp water-resistant.

Conclusion: Coatings and Barriers for Natural Fiber Materials

The use of synthetic polymers is inherent in the production of cardboard and paper. In addition to process additives, other synthetic polymers are used to provide cardboard and paper with certain technical properties, aiming to make the packaging water- and grease-resistant and suitable for direct food contact. Polymer application can occur through:

The application of extrusion coatings and laminates that form a physical layer on the surface of cardboard and paper.
The application of varnishes and/or water dispersions through coating methods and printing processes.
The treatment of cardboard and paper with various chemical substances during the pulping process or as a post-treatment.

These techniques are also applied to other pulp-based packaging, such as sugarcane bagasse.

Conclusion: Comparison of Barrier Techniques

The main difference between standard plastic coatings and other barrier methods, including water dispersions, is that standard plastic coatings have a solid form during application. Although the material can be melted during application, the layer applied to the fiber material remains solid after cooling, resulting in a composite material.

Other barrier methods, including water dispersions, use liquids that are either partially or fully absorbed into the fiber material. Depending on the application method, these liquids can form a film layer on the surface after drying that is not physically separable from the substrate.

Innovation in Nano Coatings: The Solution from NanoEnzo

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