Interview: “Triumphal march as a joining technology”

Why are the boundaries between coatings and adhesives and sealants becoming ever more fluid?

Dr Jürgen Wegner: To put it crudely, coatings could be described as ‘pigmented adhesives’ and adhesives as ‘unpigmented coatings’. From a formulation point of view, these two product categories frequently differ from one another only in the detail, and it therefore makes sense, for the very reason that the materials are closely related, to keep the boundaries between them fluid when it comes to defining the respective products. What is happening is an ongoing ever-widening overlap between the two categories.

For the vanishing boundaries between paints and coatings on one hand and adhesives and sealants on the other are inextricably tied up with the rapid growth in the number of new, extremely innovative functionalities, which often specifically target this boundary area and which, through a combination of performance optimisation and often more favourable ecological lifecycle balances and streamlining, do support genuine additional benefits. In addition to the above-mentioned functionalities, other contributors to the vanishing boundaries are permanent advances in polymer technology, the increasing use of formulation components based on renewable raw materials, and relentless advances in increasingly sophisticated coating, metering and application technology.

Dr. Jürgen Wegner

ChemQuest Europe

How would you describe the market for adhesives and sealants at the moment?

Wegner: The European and global adhesives markets, are operating at a high level, some 20 to 30% above the respective GDP. There are various reasons for this and they are certainly not due solely to ongoing softening of the boundary with coatings. A key role is also played by the no less important process of substitution, which gives preference to adhesives and sealants over other joining methods, whether thermal and/or mechanical. Boosted as it is by technological trends – such as new high-performance materials, lightweight multi-material components, rapid tightening of requirements concerning material and energy efficiency, as well as feedstock recycling marking the start of the circular economy coming inevitably down the line – adhesive bonding is set to continue its triumphal march as a joining technology for which there is no alternative in the long term.

What are the current trends in new functionalities?

Wegner: Here, it is necessary to make a sharp distinction between type of adhesive and very precisely defined application segment. You see, an all-round adhesive is at best a good marketing idea for DIY, but from a technical point of view it is a mere illusion, because while it may solve many problems quite well, it is rarely the best solution for any specific one. It would take very detailed knowledge to develop a system solution which would solve each individual case in the overwhelmingly industrial area and which would not only factor in issues of future load and specific customer expectations, but also take account of every single step of product assembly, existing and expected regulatory requirements, the whole gamut of standards-based requirements, industrial and consumer protection, as well as environmental, life expectancy, repair and recycling requirements.

All too often, adhesives constitute far less than one percent of a product’s overall manufacturing costs. However, if all assembly workflows and target-group requirements were fully transparent, the adhesives could be given very specific functionalities that would lead to performance enhancements and streamlining effects that would punch above this 1% limit. If, for instance, incorporation of a given functionality were to eliminate a cost-intensive step, that would undoubtedly be a great help to the industrial adhesives processor.

Or if additional functionality were to enable an adhesives-processing customer to finally deliver the performance he promised to his customer, that would certainly be a very welcome innovation. Again, in the electronics sector, adhesives that are electrically conductive and so eliminating soldering processes are coming to the fore. Conversely, there are adhesives which have a defined dielectric constant, i.e. an additional electrical insulation effect, but which nevertheless need to have high thermal conductivity. So, functionalities that are highly contradictory from a physical perspective therefore pose a genuine, but eminently solvable challenge.

To summarise: there is definitely no all-encompassing solution, but such a solution often becomes quite probable when the adhesives maker is taken into confidence and is involved in the process workflows and problem solving of a project from the outset. It is my firm belief that transparency, which is often lacking between adhesives manufacturers and processors, pays off in each and every single case, and gives a definite boost to the entire innovation process!

Event tip: Do you wish to learn more about adhesives and sealants formulation? Our seminar “Composition of reactive sealants and adhesives” (December 05, Amsterdam, the Netherlands) will familiarise you with the most important types, focusing on the composition and ingredients of the different kinds of adhesive with their chemical structures and functional groups, so that you will be able to clearly deduce the resulting properties.