Experts: Steffen Maier (Sika)
As a result of developments in adhesives and sealants, bonded products are generally becoming more sustainable. There are more ways to achieve this than just by using renewable raw materials. The use of adhesives can also lead to material savings, extend the service life of products or improve the insulation of buildings, thus allowing more efficient use of resources, such as energy and materials. Going forwards, moreover, product costs will not only be determined by raw materials, but also by the carbon footprint. In the adhesives and sealants industries, firms that provide the relevant data will have a clear business advantage.
Picture: Jcomp, Freepik
Sustainable adhesives and sealants make products more sustainable in general. The carbon footprint of a component should be optimised over its entire life cycle. The question of whether the adhesive or sealant is made from bio-based or recycled raw materials is not the only decisive factor here; what is much more important, is that the bonded product as a whole becomes more sustainable. This can be achieved in many different ways: by reducing weight via material savings, by extending the product’s service life, by improving insulation properties, but also by ensuring that the adhesive does not hinder recycling of the component.
Today, there are already adhesives and sealants based on renewable raw materials like maize. Such an approach only makes sense if it does not compete with food streams. Moreover, the properties of sustainable raw materials do not cover all areas of application. Chemistry, with its modular principle, offers much more diverse possibilities for widespread use. Thanks to technological progress, the number of available materials is increasing, which is a driving force for the development of new adhesives.
Adhesive bonding and sealing is an established joining method and is used wherever different materials have to be attached to each other. For certain material combinations, such as glass and metal, adhesive bonding is the only viable joining method. Adhesive bonding and sealing occurs, for instance, in building construction, wind and solar power systems, lightweight construction, vehicle construction, and also the food industry. Adhesives not only join components, but also have an influence on the structural strength or stability of the bonded parts. For example, bonded car windows are a load-bearing element of the car body and contribute to its stability; the same applies to bonded insulating glass for window panes.
In the future, thanks to new types of adhesives, joining methods like riveting, welding and screwing will increasingly be replaced by adhesive bonding. The possible applications are wide-ranging, due to the fact that adhesive bonding makes better use of material strength than other methods: With bonded parts, the force acts on the surface and not at specific points; the materials used can therefore be thinner, which reduces weight and often saves energy as well. Unlike rivets, screws and welding spots, adhesives have an insulating effect. All these properties aid sustainability and reduction of the carbon footprint.
In order to make the most of adhesives’ positive characteristics and to contribute to sustainability in many industrial sectors, it is essential that firms break new ground and seek new solutions. Only then can adhesives and sealants offer an opportunity for products to be less toxic and thus safer, and for resources to be used more responsibly. This also includes indirect benefits, such as saving energy in manufacturing processes if further developments mean that adhesives can be processed at lower temperatures or process steps can be omitted. In the future, it will not only be the raw materials that determine product costs, but also the overall carbon footprint. Firms that address the issue early and can provide the relevant data will have a clear business advantage. Swiss firms are well positioned to take advantage of these opportunities: They are leaders in the field and have established cooperation with universities, along with good infrastructure and legal security.
Technical progress is needed for the described applications to become reality. One major challenge is that of replacing toxic and problematic substances, like solvents, with water-based products, for example. This would also improve acceptance in society. At the same time, the trend is moving away from maximum adhesive performance and towards "debonding on demand": Adhesive strength should be reliable throughout the product’s service life, but at the end of the life cycle, the components should be able to separate in response to a stimulus, such as induction, electricity or a change in temperature. To ensure that adhesives do not hinder the recycling process, it should be possible to remove them from bonded parts without leaving any residue. However, it is also conceivable that adhesives could be made from the same base material as the part to be bonded: For recycling purposes, this represents a homogeneous material – and a major challenge for the chemistry behind the adhesives. In construction, there is the additional problem that, in old buildings, it is not known which material was used where. For newer buildings, building information modelling provides a remedy.
The pressure from regulatory authorities for stricter regulation or banning of established raw materials will continue to increase, as will the effort and cost involved in meeting the tougher requirements. This has an inhibiting effect on innovation. Furthermore, SMEs are often unable to cope with such expenses and are overwhelmed by the ever-stricter requirements and growing complexity in the approval process.
In order for Swiss firms to master the transition to sustainable adhesives and sealants, international market access is important: Internationality is a reality in both research and business. In addition, new regulations should be implementable and internationally harmonised; national solutions hinder progress.