Welding uncoated paper with ultrasound

In order to reliably bond uncoated paper, additional resources in the form of potentially environmentally harmful adhesives or staples have always been required. In future, paper can be bonded much more sustainably using ultrasound alone. What has been successfully confirmed under laboratory conditions is now to be established on an industrial scale for the first time will be realised. To this end, Herrmann Ultraschall will test the innovative process on applications together with customers in its state-of-the-art ultrasonic laboratories and thus further optimise it.

„Previously, we needed at least a small amount of plastic in the material in order to ultrasonically seal paper - we can now do without this completely. This opens up completely new possibilities for the environmentally friendly design of packaging. This is a major milestone on the way to a functioning circular economy. We are delighted that, together with Syntegon, we have been able to create the framework conditions to make this innovation ready for series production.“

Thomas Herrmann, CEO at Herrmann Ultraschall

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„In the Herrmann Ultraschall Group, we have found a competent partner who will bring this promising technology to all packaging applications with fibre-based materials,“ says a delighted Dr Johannes Rauschnabel, Head of Advance Development at Syntegon. „Thanks to the ultrasonic expertise of our partner the prerequisites for broad acceptance of the process created in the market.“

Ultrasonic welding of paper works in a similar way to plastics, but with one crucial difference: The material must be moistened before the welding process. The welding tool, the sonotrode, transmits the ultrasonic vibrations to the paper, whereby the fibres are separated and re-linked at the contact point of the paper layers. The frictional heat generated between the materials vaporises the applied moisture during the process without damaging the paper. This creates a high-strength and visually perfect bond within a very short time.

The areas of application for ultrasonic welding of paper are diverse: from primary packaging such as fruit trays made of thin cardboard to secondary packaging in the form of paper bags. The big advantage for companies is In addition to the savings in joining agents, the main benefits are low energy consumption, fast process times and extremely low wear on the welding tools. In addition, uncoated paper is much easier to recycle, which further improves the sustainability balance of packaging.

Source: Herrmann Ultrasound