Say no to GLYMO

The packaging supply chain has many elements that go under the radar that can have crucial repercussions for the product and its sustainability marketing potential. Adhesives certainly come into this category; while consumers are unlikely to chose a product off the shelf for its adhesive alone, if the branding can claim 'vegan', for example, then they might, without even realising it.

In terms of EU regulations, decisions are made regarding these many elements, encouraging manufacturers and converters to behave in a certain way in advance of legal ruling when these guidelines become enforceable. The latest hot topic to be chattering through the adhesives sector is GLYMO, or, to be precise, GLYMO-free.

An epoxy silane, GLYMO is an adhesion promoter widely used in food-contact packaging. Commonly used in applications such as laminated pouches that need to be resistant to hot filling and sterilisation, including microwaveable pouches, GLYMO has been under the European Food Safety Authority (EFSA) spotlight due to its concerns over existing toxicological data. The EFSA reported in 2017 that 'GLYMO is considered to have a genotoxic potential', which relates to the 'property of chemical agents that damages the genetic information within a cell causing mutations'.

Epoxy silanes are have many attributes, making them a popular choice as an adhesion promoter as they increase the adhesion between polyolefin films and aluminium, keeping the bond between them strong even when they are put under very high temperatures.

Adhesive leader

The world's market leader in adhesives, Henkel is a global Dax 30 chemical and consumer goods manufacturer, founded in 1876, with famous brands including Loctite, Persil, and Schwarzkopf in its portfolio. Dr. Monika Tonniessen, Henkel's Head of Food Safety Compliance – Global Food Safety, Product Safety and Regulatory Affairs, spoke to Converting Today to share how the company is leading the way in developing and producing GLYMO-free adhesive solutions. With the EFSA's report leading to the EU working on legislative framework to regulate the use of epoxy silanes according to their genotoxic potential, the increased demand for suitable alternatives is apparent.

Henkel is known for being active early in regulatory issues and, as such, has both researched suitable testing opportunities and is bringing GLYMO-free products to the market. Henkel is also offering various free webinars under its 'REThink Packaging' banner, discussing packaging as an overall concept, integrating the interaction of its various components, manufacturing and recycling processes. Dr. Tonniessen says, “From new legal regulations, as with the case of GLYMO, to the ever-present subject of sustainability, the packaging industry is currently in the eye of a storm of major changes and challenges. So the exchange of expertise is especially important for the industry. With out webinars, we are able to provide the entire supply chain in the packaging sector with strong support in the form of information on the various issues affecting it.”

The handling of GLYMO as an adhesive promoter is certainly an issue in the packaging sector, as the trend for laminated pouches has grown rapidly, seen as a practical, reliable and affordable packaging solution, particularly as its flat-pack transportability makes for positive environmental credentials. Yet the pesky GLYMO issue rather negates that, even though trade groups have advised to communicate to consumers with caution to avoid unnecessary alarm. However, the European Union's plastic regulations has advised on limiting the use of epoxy silanes for several years, with the recommendation to avoid it all together only coming into effect by the end of 2020.

Following the 11th Amendment to the EU Plastics Regulation (EU 10/2011), GLYMO has now been assessed as potentially genotoxic. A limit of 0.15 µg/kg has been defined to ensure its safe use for food applications. The substance is explicitly allowed to be used. Nevertheless, it also means the packaging producer has to verify that its concentration as well as that of its derivatives remains below the specific migration limits under conditions of use.

The driving force

Dr. Tonniessen explains how Henkel is committed to maintaining its reputation as 'the driving force in the field of laminating adhesives that enable food-safe packaging' by introducing a new GLYMO-free solution to the market, Loctite Liofol LA 2798. Developed especially for high-performance packaging applications including thermal processes such as sterilisation, the new Henkel solution is completely free from GLYMO, epoxy silane and heavy metals.

Tonniessen says, “We take the legislation very seriously and we are always keen to make a proper risk assessment. This is possible because my colleagues in the analytical and toxicological department can be contacted at any time for substances not listed in the EU legislation. We in Henkel call this our 'triple safety concept'. It is a great advantage to have such an expert team in the company. Based on the assessment of our toxicological experts, already in 2012 we informed our customers in detail about the possible genotoxic potential of GLYMO and other epoxy silanes in our food contact statements. Today, we clearly explain that by replacing GLYMO with GLYEO [a bifunctional organosilane possessing a reactive organic epoxide and a hydrolyzable inorganic triethoxysilyl group] is not what we consider a solution. Even though there is currently no EFSA opinion published on GLYEO, from the toxicological point of view, both GLYMO and GLYEO have the same critical structure.”

The extensive in-house R&D capabilities at Henkel support the company's dedication to creating and offering a GLYMO-free adhesive solution, with Loctite Liofol LA 2798 available since June 2019. Tonniessen continues, “Due to our in-house toxicological assessment, our colleagues in R&D had already been alerted a few years ago and therefore started to develop alternative GLYMO-free adhesives, not only one product but a modular system of different products covering different applications. Our aim is not to be ahead of regulations, but rather to look for alternative solutions for our customers to constantly improve the safety of our adhesives.”

Loctite Liofol LA 2798 has been created as a modular system to enable high versatility, allowing the base component to be combined with different hardeners for the respective area of application, such as sterilisation processes, aggressive filling goods, and hot filling processes. Helga Garmann, Henkel's Manager Product Development Polyurethanes Europe, shares how the product has applications ranging from pet food and medical products to convenience goods. A limit of 0.15 µg/kg has been defined to ensure its safe use for food applications. The substance is explicitly allowed to be used. Nevertheless, it also means the packaging producer has to verify that its concentration as well as that of its derivatives remains below the specific migration limits under conditions of use. Garmann says, “Common flexible packaging adhesives in the high-performance segment may still rely on GLYMO as an adhesion promoter. Henkel, however, has always attached the highest importance to offering clean and uncritical formulations. As testing is complex, we recommend the use of adhesives that do not contain any GLYMO.”

As well as being GLYMO-free, Loctite Liofol LA 2798 the formulation is also free of substances such as neopentyl glycol (NPG), hexanediol, tin, and bisphenol A (BPA), making it safe for fatty foodstuffs, oil fatty acids, and alcoholic contents. Garmann adds, “The adhesion properties and performance of our modular system have already been confirmed during industrial use by several of our customers. The product is commercially available and we are looking forward to further introducing it to our customers and clients in the packaging industry.”

In addition to Loctite Liofol LA 2798, Henkel currently offers four hardeners with which the GLYMO-free product can be combined, each created with different features to support a broad range of applications, specifically in order to provide safe options for the packaging and sterilising of aggressive liquids, including baby foods, as well as fatty foods and foods with oily contents, such as pet foods.

With increased consumer awareness and tighter legislation about chemicals in packaging bringing both challenges and opportunities for differentiation and being ahead of the developmental curve, the considerable interest in GLYMO-free solutions is unlikely to go away, particularly in relation to the circular economy and more sustainable packaging solutions. These forward-thinking solutions still share the performance properties that brands require, even with agressive fillings, and are also microwaveable, which continues to be important for food products and on-the-go convenience products, a trend that continues to grow, particularly in the healthy choice and vegan categories, both of which are especially sensitive to the sustainable packaging sector and represent excellent opportunities for development and innovation. Chemical regulations don't go backwards, so to carefully and cleverly create GLYMO-free adhesive solutions that see beyond today's allowance and look to tomorrow's decisions is more visible to a company's bottom line tha