Barrier coatings are a game-changer in packaging, enhancing product protection and extending shelf life. These coatings offer a vital solution to maintain product quality by safeguarding against environmental factors. But how exactly do they work, and what are the broader implications for industries and sustainability?
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Barrier coatings are specialized materials applied to packaging surfaces to protect contents from environmental factors like moisture, oxygen, and ultraviolet (UV) light. These coatings typically consist of thin layers of polymers or bio-based materials designed to create a protective shield around the product.
The mechanism of barrier coatings involves blocking or slowing down the passage of gases and vapors. This is achieved by creating a dense molecular structure that prevents the penetration of harmful elements. By doing so, barrier coatings are crucial in maintaining the integrity and freshness of packaged goods.
Barrier coatings play a significant role in enhancing packaging sustainability by reducing the need for complex multi-layer packaging solutions. Traditional packaging often relies on multiple layers to provide adequate protection, leading to increased material use and waste.
By using barrier coatings, manufacturers can achieve the same level of protection with fewer materials. This not only minimizes environmental impact but also supports the development of sustainable packaging solutions. Additionally, as barrier coatings can be applied to bio-based materials, they further contribute to the reduction of reliance on fossil fuels.
The food and beverage industry is one of the primary beneficiaries of barrier coatings. Coatings ensure that products remain fresh and safe for consumption by preventing spoilage caused by oxygen and moisture. This is crucial for extending shelf life and reducing food waste.
Similarly, the pharmaceutical and cosmetics industries gain significant advantages from barrier coatings. These coatings provide the necessary protection to maintain the efficacy and stability of sensitive products, ensuring they reach consumers in optimal condition. In both sectors, the ability to maintain product integrity is essential for consumer safety and satisfaction.
Barrier coatings offer several economic benefits, primarily through cost savings associated with extended shelf life and reduced spoilage. By ensuring products remain fresh for longer, manufacturers can minimize losses due to expired or spoiled goods.
Moreover, barrier coatings reduce the need for excessive packaging materials, resulting in lower material costs. This reduction in packaging complexity can also lead to decreased transportation and storage expenses, further enhancing the economic appeal of barrier coatings.
Barrier coatings are essential in modern packaging, offering numerous benefits such as enhanced product protection, sustainability, and economic advantages. By understanding the mechanisms and applications of barrier coatings, industries can make informed decisions to optimize their packaging strategies.
For those interested in exploring these benefits further, we at KCL are ready to support your packaging needs with our expertise in coating technology and sustainable solutions. Whether you’re looking to enhance product protection or reduce environmental impact, our services are tailored to meet the demands of the evolving bioeconomy.
Barrier coatings and barrier layers are a key part of many types of packaging. They are used in packaging for industrial goods, consumer and household products and pharmaceuticals, but the main market is for food and beverage packaging. Barrier coatings help protect food and drink from moisture, oxygen, grease and light and so extend shelf life by maintaining product quality. They are used in food packaging for snacks, bakery products, and ready-to-eat meals, and in paper cups, and milk and juice cartons, for beverages. The paper and board packaging market used 3.3 million tonnes of coating materials in . Up until recently, barrier layers have been made from petroleum-derived polymers and aluminium and although they make up a small percentage of the mass of the packaging, their presence has greatly affected how packaging waste is processed.
In , the EU generated 83.4 million tonnes of packaging waste and the USA produced around 72.6 million tonnes. The addition of barrier coatings creates mixed-material packaging. The coating layers can be difficult to separate from the bulk of the packaging and some layers may theoretically be recyclable but others aren’t, and this makes the overall packaging difficult to recycle. So municipal waste processors often treat mixed material packaging as non-recyclable. Add to this the problem of food or drink contamination on the packaging, and it seems less surprising that a lot of packaging waste goes to landfill or is incinerated. The problem of packaging is only getting worse. Over the 10 years from to , the amount of packaging waste generated in the EU increased by 20% and this trend is likely to continue.
There are a range of approaches for improving the sustainability of packaging. When comparing the merits of different packaging types, academic studies have shown that the choice of raw materials used to manufacture the packaging, and the end-of-life destination of the materials have large effects on CO2 emissions. Switching to bio-based materials, rather than petroleum-derived polymers, can have a big benefit as can improving the recyclability of the packaging. So many companies are moving to paper and board-based packaging rather than plastic. Manufacturers of packaging are also working on “lightweighting”, reducing the amount of material used, whilst still maintaining packaging strength and properties. Using green energy or switching to less energy-intensive manufacturing processes can also lower associated CO2 emissions. The choice of material used as a barrier layer in product packaging can affect several of the steps in the packaging’s life cycle.
Tetra Pak has been a pioneer in the use of plant-based polymers as moisture barrier coatings. In , they launched Tetra Rex Plant-based. This beverage packaging is made entirely from plant-based renewable materials including paperboard from sustainable forestry and plant-based polymers for the external and internal barrier layers. The two thin layers of polyethylene (PE) prevent moisture from getting in or out of the carton. The plant-based PE coating, derived from sugarcane, has the same recyclability, functionality and food protection properties as petroleum-derived PE polymers but has a lower climate impact.
Tetra Pak has also developed packaging where aluminium-coated polymer films have been replaced with metallised, paper-based barriers. An aluminium foil layer is added to beverage cartons as a barrier to oxygen and light and it helps to protect the nutrients and flavours of the product. In , Tetra Pak launched an aseptic beverage carton with a paper-based metallized barrier. The packaging was trialled by Portuguese food company, Lactogal, who used it to package milk that could be distributed under ambient conditions. The paper-based barrier in the Tetra Brik Aseptic 200 Slim Leaf carton has a 20-30nm thick, aluminium coating developed and manufactured by Nissha Metallizing Solutions. The use of the metalised, paper-based barrier has increased the renewable content of Tetra Pak’s Aseptic 200 carton to 90%.
Dispersion coatings are barrier layers that are said to be more sustainable because of the way they are applied to the packaging which is different from extruded polymer film layers. Liquid polymer dispersions, usually water-based, are typically sprayed onto the surface of cardboard rather than being a separate polymer film layer that is glued in place. The advantages of using a dispersion coating is that less polymeric material is used to make the packaging, which results in a higher proportion of paper or cardboard per item, but the resistance to humidity, grease and mechanical stress is retained. For example, Dow markets a range of polymer dispersions under the brand RHOBARR that contain petroleum-derived, polyolefin polymers.
Mixed materials like food and drink packaging, manufactured with barrier coatings, are difficult to recycle because of the presence of several different materials. Specialist recycling facilities are often needed to process the packaging waste. For example, Tetra Pak has a program of investing in recycling facilities to increase the rate of recycling of all the components of Tetra Pak brand cartons and there are now around 200 facilities globally. The pulp fibre can be recovered and made into cardboard boxes, paper tissues and paper bags, and the PE polymers and aluminium are combined into pellets and used in injection molding applications, for example they are made into warehouse pallets, outdoor furniture and floor panels. Despite the millions of euros invested, in only 27% of Tetra Pak packages were recycled, corresponding to 49 billion cartons. This is much higher than the <1% of paper coffee cups that are recycled in the UK. Waste management company, Recorra, is one of the few companies that offer to collect used coffee cups as a separate waste stream, that is then sent for recycling.
When dispersion coatings were launched, manufacturers claimed that switching to their materials would make packaging more sustainable and more recyclable, but environmental concerns about them being a source of microplastics and nanoplastics have now surfaced. The mass of petroleum-derived polymer applied to packaging in a dispersion coating is less than a glued-in PE layer. Example data from the industry indicate that PE layers can be present at a level of 15g / m2 packaging, whereas aqueous, dispersion coatings are present at 6g / m2 packaging, which is typically <10% of the total weight. As a result, paper-based packaging with dispersion coatings can be categorised as being suitable for paper recycling.
However, many recycling facilities cannot handle the aqueous lining residue that is coated onto the paper fibres. The polymers, often polystyrene or acrylics, are often not recovered in the recycling process, but due to their small size, the plastic particles, are discharged into the wastewater effluent from paper recycling mills and can then pass into rivers and ultimately contaminate our environment, with concerning, long-term health consequences.
Bio-based coatings really come into their own for food service packaging. Several companies have developed polymeric coatings that are now coming on to the market. Danimer Scientific has supplied Chinese company, Ningbo Homelink Eco-iTech Co. Ltd. with their extruded polyhydroxyalkanoate (PHA) coating, Nodax ®, which Homelink have used to produce home and industrially compostable cups that they claim will also be fully repulpable. Nodax is a replacement for PE. UK companies, Notpla and Kelpi are both extracting polymers from seaweed to use in a range of packaging applications. Notpla say that their seaweed-coating will allow paper packaging to biodegrade in weeks, so that it can be composted just like food waste. Kelpi’s website says they are working with packaging companies to develop recyclable, biodegradable coatings, for paper, card and fibre to produce long shelf-life, sustainable packaging. Earthodic, an Australian start-up is using lignin, a substance found in wood and a waste product of the pulp and paper industry, as a key ingredient in their paper coating technology. Their Biobarc™ coating is water-resistant and will protect paper-based packaging from moisture and increase its strength by up to 15%. They intend their packaging to be repulped and recycled at the end of its life.
Non-profit and industry organisations are exploring the issues arising from the diversification of coating technologies. The Ellen MacArthur Foundation recommends that manufacturers should use regeneratively sourced paper with a coating that has the same biodegradation profile as paper. The Confederation of Paper Industries is not so restrictive and says that although they welcome and support the development of alternative barrier technologies, the implications of those barrier coating materials need deeper examination, with regards to their impact, both within the finished paper and in wastewater. The extent of this impact is currently unknown, necessitating additional research to better understand the challenges.
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Strategic Allies has a keen interest in sustainability and the circular economy for packaging. We see the packaging market as dynamic, with many factors driving change including regulations, supply and demand, consumer behaviour and the benefits and ease of implementation of different coating technologies.
As an Open Innovation services company, Strategic Allies has extensive experience in the global search for innovative technologies, solutions, products, strategic alliances and other new business-generating opportunities across all sectors. If you’d like to find out more about how we can help you to explore and exploit new technologies and/or offer opportunities to differentiate your offerings, please contact John Allies at
References
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Per- and polyfluoroalkyl substances (PFAS), often referred to as 'forever chemicals', have increasingly become the focus of attention due to their persistence in the environment and potential health risks. Our ComBa liners are completely free of PFAS while still providing excellent barrier properties against water, grease and acids. By not using PFAS in our coatings, we ensure that your packaging is not only functional, but also environmentally and health friendly.
If you are looking for more details, kindly visit Barrier Coating for Paper Cups.