Sustainable adhesives and sealants

*Updated version of the 2023 article.

Definition

Adhesives and sealants are materials used for permanently bonding different materials or for sealing applications. They are considered sustainable if they manufactured from renewable raw materials and can be disposed of in an environmentally friendly manner or are biodegradable. However, one major advantage of innovative adhesives and sealants lies in the fact that they make the end product more sustainable overall, since they offer several advantages compared to other joining techniques such as riveting, screwing or welding: For example, forces in bonded parts are distributed across the surface rather than at specific points, allowing bonded elements to be thinner, which saves raw materials, weight and often energy in the end product. Bonded joints are often more durable and thus extend product lifespans. Additionally, sealants and adhesives have insulating properties that contribute to energy efficiency in the likes of buildings. All of these properties increase sustainability and reduce the carbon footprint of bonded products. 

Current applications and opportunities

The construction sector is one of the most significant global application for adhesives and sealants. In vehicle construction, the trend towards lightweight body construction and the increasing demand for batteries in electromobility are driving demand for innovative adhesives and sealants. Thermosetting composite materials for wind turbine rotor blades are also bonded. Other important areas of application include the packaging, clothing and consumer goods industries. Adhesives also have an influence on the structural integrity or stability of bonded parts. The addition of additives enables them to perform numerous additional functions such as protection against moisture, vibration damping, electrical or thermal conductivity, UV stability and other innovative functions. 

For industrial manufacturing, adhesives and sealants offer numerous advantages. They enable lighter and more efficient designs, for the likes of more energy-efficient lightweight vehicles. The application of adhesives and sealants can often be automated, increasing the process speed. Indirect successes also contribute to overall process sustainability, for example when adhesives can be processed at lower temperatures, enabling more energy-efficient manufacturing processes. Adhesives and sealants protect components from corrosion, since no drilling is required. This in turn extends the service life of the end product. 

In Switzerland, both industry and university research are driving development forward. Important impetus also comes from political requirements such as the net-zero target for greenhouse gas emissions and the regulations set out in the EU Chemicals Regulation REACH, which Switzerland has largely adopted. Adhesives and sealants play a key role in the transition to a sustainable economic model. For most Swiss companies that are active in the adhesives sector, international market access is important, particularly in the EU internal market. Both research and business embrace internationality.  

Challenges

Conventional petrochemical adhesives and sealants still hold the largest share of the market. The field of bio-based adhesives, which are manufactured at least partially renewable raw materials such as natural wood-based polymers or agricultural waste, is developing very dynamically. However, the use of bio-based raw materials as starting materials for adhesives and sealants is not always sustainable. This is because they may compete with food production, and the manufacturing process can be more energy-intensive than with fossil sources. Furthermore, due to their properties, sometimes limited availability and natural quality variations, bio-based raw materials rarely suffice as a complete replacement for all applications of conventional adhesives and sealants.  

Achieving net-zero targets requires a favourable end product carbon footprint over the entire lifecycle. To quantify the contribution to the carbon footprint, the chemical industry favours the mass balance instrument. In a voluntary certification system such as ISCC Plus (ISCC = International Sustainability and Carbon Certification), all substances that are fed into, converted within and discharged from a chemical manufacturing process are meticulously recorded and their carbon footprint is attributed proportionately to the end product. The advantage of this is that fossil and bio-based (or recycled) raw materials can be incorporated into the same production process without any need for separate production facilities or additional approval permits for each of the two streams. 

Another challenge when it comes to sustainable adhesives and sealants is the recyclability of products at the end of their lifecycle. To ensure that adhesives do not hinder the recycling process, it is often advantageous if they can be completely removed from the bonded parts without leaving behind any residue. One technological trend often discussed in this regard is debonding on demand. Here, the adhesive strength must be reliable throughout the entire product service life, but at the end of the lifecycle the components should separate from each other in response to a stimulus such as induction, electricity or temperature change. It is also possible for adhesives to be manufactured from the same base material as the product to be bonded. This is called “mono-material design”. This results in a single-variety material for recycling. 

Pressure from the regulatory authorities to regulate proven raw materials more restrictively or ban them will continue to mount. For example, in 2023, the EU restricted the use of isocyanates, which enable curing of adhesives and sealants. This results in conversions and additional costs in the production process. SMEs can barely afford these costs and are severely challenged by the increasing requirements and complexity of the approval process. 

Focus on industry

Sustainable adhesives and sealants play an important role in the procurement of basic chemicals, production and marketing. In the future, product costs will be determined not only by the raw materials, but also by the carbon footprint of the entire value chain. Companies that engage with the topic early on and can provide the corresponding data, using a certified mass balance, for example, will have a clear business advantage.  

Experts in the field of sustainable adhesives and sealants require knowledge of plastics chemistry with specialist expertise in bonding processes. Developers should have a good understanding of customer requirements for adhesives and be able to create added value for customers. Training and further education mainly takes place in the companies themselves. While there is no threat of a shortage of skilled workers amongst chemists with university degrees, recruiting sufficient chemistry laboratory technicians remains a problem. 

International perspective

The EU is at the forefront of the global market for sustainable adhesives. In Switzerland, there are several players in both research and business who play an important role in developing new adhesives and sealants. Particularly in a country like Switzerland, it is crucial that companies can offer innovative and technologically advanced products to compensate for high material and labour costs through good margins. There is little prospect of beating competitors from Eastern Europe or East Asia on price alone.  

Future applications

Thanks to innovative adhesives, joining methods such as riveting, welding or screwing will increasingly be replaced by bonding in future. There are now over 250,000 adhesive formulations, and the number continues to grow. New developments enable the bonding of an ever-greater variety of materials, which also expands their fields of application. Swiss companies are in good positions to seize these opportunities. They are leaders in this field and have established partnerships with universities, not to mention modern infrastructure and legal certainty. 

Sustainable adhesives and sealants play an important role in the circular economy and in achieving the net-zero target. They contribute to products’ energy efficiency and longevity – for example in building services or lightweight construction. New developments in research also target recyclable, bio-based or reversible adhesive systems that can be dissolved again using heat or electricity, for example. Adhesives and sealants thus also increasingly support circular economy concepts and resource-conserving production methods.