Monomaterials such as monolayer films and new composites such as OPP / PP (oriented polypropylene / polypropylene) tend to be less resistant than conventional packaging materials. The temperature differences between carrier and sealing layer are lower and thus the process window becomes smaller during sealing. The ultrasonic technology can provide good sealing results with monomaterials, even with narrow process limits, especially in terms of tightness and appearance. Other technologies have limitations and can cause material shrinkage, thermal expansion or sticking of packaging material to sealing tools.
Ultrasonic sealing of cardboard composites without an aluminum barrier is already a proven process, and even bio-plastics such as PLA show good sealing behavior with ultrasonics.
The number of inquiries with new recyclable materials in the ultrasonic laboratory at Herrmann Ultraschall is increasing, especially since many food companies have set high sustainability goals. Even the legislature speaks, so in England where meanwhile composites of different materials are prohibited.