Packaging that is discoloured and has grease stains is completely unacceptable! After all, packaging – even if it is made of paper or cardboard – is not simply expected to protect the product; it is also expected to whet the appetite for the contents. To prevent pizzas sticking to the base of the box, grease leaking out of bags of chips or sandwich wrappers and drinks soaking beverage containers, the packaging needs to be resistant to oil and grease.

By Dr Bettina Plaumann

Traditionally, per- and polyfluoroalkyl substances – known as PFAS for short – are used for such applications. Unfortunately, these chemicals are not sustainable. They have a negative impact on the environment. However, there is an alternative:ExcevalTM, a water-based coating which is just as effective as conventional barrier substances but does not contain fluorine-based chemicals.

To make sure that paper packaging looks perfect – without unsightly stains and discolouration – it has to be resistant to oil and grease. To ensure this, the packaging industry has used synthetic PFAS since the 1950s. These fluorocarbon compounds are non-stick, water-resistant and greaseproof. However, PFAS are now controversial. They are subject to increasingly strict regulation and are unpopular with consumers, who are increasingly concerned about sustainability.

Despite their usefulness, there are serious concerns about the environmental impact of PFAS. Because of their extremely long life, they are often known as forever chemicals. As a result of their stable chemical bonds,they decompose very slowly in natural conditions. Therefore, an apparently eco-friendly paper cup with a PFAS coating continues to pollute the environment long after the end of its useful life. If the packaging is not disposed of correctly, PFAS affect aquatic ecosystems and marine life by disrupting their equilibrium.

Governments, public authorities and NGOs around the world have recognised the urgency of this problem. "PFAS are coming under increasing Öl- und fettabweisende Verpackungen wurden traditionell mit polyfluorierten Alkylsubstanzen beschichtet. (Bild: freepik) Packaging traditionally has been coated with polyfluorinated alkyl substances to repel oil and grease. (Image: freepik) 3-4/2024 sweets processing 47 Packaging scrutiny in Europe and the USA and brand owners are looking for new, sustainable solutions,” says Heiko Mack,Director of the Poval Division at Kuraray. The European Chemicals Agency (ECHA) is planning to ban all PFAS – either immediately or stepwise, depending on their application. Others are following suit: ChemSec, an NGO, has added 370 PFAS to its SIN list and at least 28 states in the USA intend to introduce measures to curb the use of PFAS. Some are even considering a complete ban on this class of chemicals.

The good news: It is easy to replace PFAS in most food contact and packaging applications. For example, with ExcevalTM, a fluorine-free, inherently biodegradable and repulpable barrier polymer that is used to coat paper and cardboard.

Barrier layers are applied to paperbased packaging to protect the fibres, maintain its structure and avoid stains. They protect the contents from external influences and also prevent oil, grease and liquid from the food penetrating the packaging. “Greaseproofing is not just practical because it protects the packaging from the contents. It also has an aesthetic function,” says Heiko Mack. “If the packaging is discoloured or the quality looks poor, consumers may opt for a different product. ExcevalTM offers a solution. Packaging coated with this product is highly transparent, glossy and has good printability.”

Exceval™ is a modified polyvinyl alcohol (PVOH). This nonionic polymer is soluble in water and has better moisture-resistance than other polyvinyl alcohols. It is an ideal barrier layer for packaging: Its linear, crystalline structure with water-repellent properties protects the contents reliably from fat, grease and mineral oil. Exceval™-coated packaging also offers
effective protection against oxygen and gases such as carbon dioxide. Result: Products stay fresh for longer. Even at high humidity, ExcevalTM provides a strong oxygen barrier of less than 1 cm³·m-2·day-1·atm-1. This environmentally friendly solvent- and chlorine-free coating can be used with a variety of materials. It conforms with the specifications of relevant standards — BFR 36, FDA (FCN 1179) and China GB — so it can be used without reservation for food packaging.

Typical packaging such as a paper bag could have the following structure: paper, with a protective, moistureresistant layer, an ExcevalTM coating and finally a heat-sealing layer.

Packaging of this type is already used in the food sector. A thin layer of water-soluble ExcevalTM acts as an aroma and oxygen barrier. It can be applied by conventional methods on
rotogravue and rod coating lines. Dispersions such as polyolefins or other polymers can be used for the inner layer, which provides thermal protection, ExcevalTM has a key sustainability benefit: Unlike conventional fluoropolymers, it is soluble in water, so this type of packaging can easily be recycled in paper mills. Heiko Mack: “Kuraray believes it is very important to develop sustainable packaging solutions and does not compromise on quality. After all, packaging must always fulfil its central function, which is to protect the product.”

Other Kuraray solutions that can be used as substitutes for PFAS:
• Biocircular EvalTM EVOH
• PlanticTM Biopolymer

Using PFAS in food packaging may be efficient, but it involves ecological risks. Sustainable alternatives such as ExcevalTM offer an effective barrier without fluorine or chlorine. That enables the packaging industry to set an important example for an environmentally friendly future.