Manufacturers of smartphones and other electronic devices must produce as leanly, cost-efficiently and automatically as possible to remain competitive. Additionally, consumer purchasing decisions are increasingly influenced by whether products can be recycled at the end of their useful life.

Covestro, which develops sustainable chemical solutions, is enabling electronics manufacturers to efficiently apply hot-melt adhesives — thanks to its Desmomelt U polyurethane adhesive raw-material in a digital process.

Typically, the application of adhesives to smartphone displays is often a time-consuming part of the manufacturing process. For example, adhesive foils are applied that must be precisely cut beforehand.

An analogous process is based on latently reactive two-component, hot-melt films, which are still crosslinked after the joining process to create a particularly strong adhesive bond between the components. Due to the strong bond, however, disassembly at the end of the service life is often difficult.

Now, hot-melt adhesives based on Desmomelt U can be applied exactly where they are needed using digital printing. Automation of adhesive application reduces the number of processing steps required. Nevertheless, complex, CAD-based adhesive bonding paths are possible.

In the case of thermoplastic adhesives, end-of-life recycling can also be facilitated. So, after the use of a smartphone, it’s possible to disassemble components in a temperature-controlled manner if only thermoplastic raw materials have been used. If particularly strong adhesive bonds are required, then the digital application of latent 2C reactive hot-melt adhesives, using the Desmomelt U and Desmodur crosslinkers, is also possible.

The new adhesive raw materials used in the Desmomelt U are aliphatic and protected against yellowing. They combine the advantages of water-based adhesives, which offer a higher molecular weight, environmental compatibility, and performance — with easy processing of hot-melt adhesives.

The open time can be adapted to customers’ wishes, which makes processing even more flexible.

Hot-melt adhesives based on Covestro’s Desmomelt U thermoplastic raw-material powder can now be applied automatically and in precise doses using digital printing with other processes, as well. This includes the manufacture of shoes.

Digital application features of Covestro’s Desmomelt U thermoplastic raw-material powder:

• Simple processing with accurate dosing
• No loss of quality
• Recycling feasible with thermoplastic adhesives
• Ideal for automated application in electronics assembly and shoe manufacturing

Learn more here.