Kuhne Anlagenbau to present turnkey line for shrink film extrusion at NPE 2024

At NPE 2024, Kuhne Anlagenbau will focus on large turnkey line for extruding flexible and biaxially-oriented barrier shrink films that does not require polyamide (PA) or polyester (PET) as a layer to impart strength to the structure, with use of Triple Bubble process.

Medium-sized Triple Bubble blown film lines can achieve throughputs up to 250 kg/h when producing films for recyclable, flexible barrier shrink bags.

Triple Bubble process uses gentle radiation crosslinking employed by Kuhne. This acts from the outside to a shallow depth of only 5-10 µm, without damaging the EVOH layer and reducing recyclability.

As a result, there is no need for an additional post-processing step. The resultant films are flexible and elastic to achieve good levels of shrinkage. They also provide the mechanical strength required to be able to reliably fill the bags, even with contents weighing several kilograms.

One-stop packaging solution

The turnkey line includes specification of the material formulations and gauges required for the 7-13 PE, adhesion promoter and EVOH layers, as well as all processing parameters. It can be tailored to particular product requirements and can usually be commissioned very shortly after installation.

The recyclable films mean lower extended producer responsibility (EPR) levies. They also assist compliance with the Circular Economy for Flexible Packaging (CEFLEX) sustainability guidelines drawn up by the flexible packaging value chain.

With Triple Bubble Technology, typical film thicknesses are material saving, ranging between 20 µm for lid films and 50 µm for shrink bags. A shrinkage of over 60 % is achievable. Optimized machine design and high cooling rates mean the lines can achieve throughputs of up to 250 kg/h or annual output exceeding 1500 metric tons of shrink bag film.

Depending on current requirements in different regions and applications, intermediate layers made of PVDC instead of EVOH, as well as PA or PET outer layers to increase puncture resistance are possible.

Triple Bubble Technology

The Triple Bubble technology for manufacturing biaxially-oriented blown films is named after the serial arrangement of three bubbles.

In the first process, the film is very quickly cooled using cold water quench technology. This quenching effectively prevents crystallization processes, as is essential for uniform stretching in the second stage. The resultant high degree of orientation at a molecular level is key to the films’ excellent mechanical and barrier properties.

Thermal relaxation in the third bubble is used to set the desired shrinkage behavior, making it possible to achieve very low shrinkage forces.

Kuhne’s current Triple Bubble lines enable the production of shrink films with up to 13 layers at widths of up to 3000 mm double flat (6,000 mm film width).