Breaking bonding boundaries

4 min read

A combination of diverse adhesive technologies is being hailed for its ability to provide much increased performance. But how does it work?

The use of adhesive technology for the bonding and/or sealing of components has been a significant trend for years. This is expected to continue, due to the need to find solutions for other trends such as lightweight construction, miniaturisation, digitisation etc. Due to the ability of adhesives, they are increasingly being implemented as optimal solutions, and so the cycle continues and grows.

There are a multitude of adhesive solutions available to fulfil demands in the telecommunication, electronics and automotive industries, white and brown goods, mechanical engineering, textile and packaging industries, as well as construction etc. It is the project managers who then must find the ‘right solution’ for their project; not easy.

Hardly any standard solutions exist that can be arbitrarily transferred from one application to another. In general, adhesive projects are complex and must be considered in their entirety, from the substrates to be bonded, the adhesive solution to be selected, and considered as an integral part of the total manufacturing process. Unfortunately, it is the latter that is often underestimated and leads to suboptimal results - in technical, economic and qualitative terms.

From a user perspective, adhesive projects usually have to fulfil many requirements at the same time: product quality and performance, time-to-market, cost-efficiency, process reliability and freedom of design are only a few key concepts when designers, production managers, buyers and quality managers work together on products that bring their company cost or competitive advantages. However, the basis for such products is not only innovative adhesive solutions, but also partners who master and accompany the complex process from the initial idea into production.

Lohmann pursues this approach within the framework of its ‘Smart Bonding Approach’ philosophy. “In the process, the specific requirement profile of an idea or application is mutually determined,” states Reinhold Domanski, head of new business development. “This support leads to the ultimate product selection, assistance to engineering, and continues with the support of process optimisation at the technology suppliers and any other service providers involved.

“Intelligent bonding begins with an idea, continues with optimal integration into production processes and then culminates in customer satisfaction,” he points out. “However, the boundaries of different bonding technologies increasingly compete with each other. In distinct contrast, DuploTEC SBF technology overcomes these issues in structural bonding by combining the advantages of adhesive tapes and liquid adhesives, embedded in a holistic consulting approach: ‘The Bonding Engineers’.”

Numerous mechanical and adhesive technologies are now used for bonding a multitude of materials, but their possibilities are limited, depending on the application and process. This is one reason industrial adhesive tapes are increasingly being utilised. However, limited absorption of static forces and low heat resistance tend to restrict the use of this technology in some applications. The same applies to thermoplastic films where the bond is reversible on re-heating. This can be a specific reason for using a thermoplastic adhesive tape, but could cause significant embarrassment if used in the wrong environment.

“In the case of liquid adhesives, pot lives and curing times can, under certain circumstances, be limiting factors; the dosing and mixing process has to be carefully coordinated, and certain complex safety and environmental protection measures are necessary,” he explains.

“Adhesive discharges and component contamination can also become a cost driver, due to the necessary cleaning procedures, and PPE is often overlooked as a cost directly associated to the use of liquid adhesives. The limitations of mechanical bonding techniques are well known, even if hybrid solutions - in combination with adhesive technology – are increasingly being offered. During mechanical bonding the material is altered, often being punctured. Tensions can arise in and between the material/s and the risk of corrosion, due to material damage, is not to be underestimated. Design impairment and the additional weight go against the current industry trends”

These limitations are overcome with adhesive films from DuploTEC SBF technology, he states, as they combine the advantages of adhesive tapes and liquid adhesives, and thus pave the way for new solutions. “They can be processed quickly and cleanly in all forms - as a tape on a roll, a sheet or as a prefabricated die-cut, loose or on a roll. The adhesive films are suitable in absorbing the highest static and dynamic loads, possess excellent heat resistance properties and high environmental and chemical resistance. They are safe bonding different materials, tension peaks are avoided, due to uniform force dissipation, and their plastic or, maybe better, non-metal and insulation properties are an effective corrosion protection.”

Simultaneously, DuploTEC SBF products can form an effective seal against aggressive liquids and gases, Domanski reports. “They meet the requirements of economic processes through reduced handling, clean bonds and pollution-free processes. New demands coming from design requirements are to have the smallest adhesive surfaces, bonding differential materials, with high loading, temperature, UV and chemically resistant and offer weight reduction. Designers are being offered new degrees of freedom when using DuploTEC SBF.”

Adhesive films are available in three technologies for the bonding of various materials:

  • The Topaz technology is based on high-performance polyurethane adhesive systems. The solvent-free, dry adhesive films are latently reactive and have structural adhesive properties. They cure in seconds at temperatures of 70 to 160 °C and are still highly flexible. They are suitable for individual and high-precision adhesive geometries up to 0.3 mm in width
  • The Amber technology is said to be the first commercially available cyanoacrylate adhesive system from the roll and is based on several filed patents. The adhesive film is described as being as easy to apply as an adhesive tape, and the high initial tack allows a simple and secure fixing. The auto-curing system is particularly suitable for temperature-sensitive materials, because at 70°C it cures within 1 hour or at room temperature in several days
  • The Onyx technology is based on powerful epoxy adhesives. The adhesive films have an initial tack, and can be positioned and repositioned. They cure within 20 minutes at temperatures of 130 °C to 180 °C and are therefore particularly suitable for joining substrates with high-temperature stability, such as high-performance plastics and inorganic materials.

“Taking the holistic approach of adhesive film technology and combining it with the ‘Smart Bonding Approach‘, projects can be implemented effectively and users are safe from surprises,” he concludes. “Adhesive projects are never trivial and only the consideration of all framework parameters will lead to optimal solutions. The room for further ideas is immense – as always, when existing boundaries are overcome.”