KZPM, a major producer of films, flexible industrial packaging and compounds in Kazan, Russia in February opened its doors to visitors from as far away as Texas and Korea for the premiere of its newest blown film extrusion line, an Evolution five-layer FFS line supplied by German extrusion machinery supplier Reifenhäuser. “Our line is the first of its kind for packaging petrochemicals,” said Reifenhäuser CSO, Ulrich Reifenhäuser, on opening the event. “And sacks are a truly enormous market. The scope is huge, especially the replacement market.”
Next to the on-site visit to KZPM, the event included presentations from various speakers from the industry, including from materials producers Sabic and Sibur, who addressed the current challenges and opportunities in the blown film market today.
The Ultra effect
Eugen Friedel, sales director at Reifenhäuser Blown Film ran through a few of the company’s developments in blown film technology of the past few years. “Evolution Ultra Flat, Ultra Die and Ultra Stretch have allowed us to set new standards in the sector,” he said. “And when it comes to producing barrier films, size matters. We can build dies for 9 layers that are same size as for 3 layers. More layers increase profits.”
Calling the Ultra Die the ‘most efficient’ multilayer die head, with a design giving the highest level of flexibility in terms of layer ratios and viscosities in barrier film production, he went on to explain its compact design was due to the shorter flow channels – about 70% shorter compared to existing die head designs.
“Also, processing can be done at lower temperatures, which means less degeneration, and job changes are much faster as purging is far more efficient: around 80 minutes compared to three hours with conventional axial or conical die heads.”
Ultra Flat, developed to combat camber, curl and bagginess caused by stresses in the film, can yield 40% better flatness in film, said Friedel. Reifenhäuser is working on a ‘closed loop automatic setting of flatness’, he added. What is the added value of automating film flatness? “There is an increased bond strength due to flatter films, which means less glue is needed, saving costs,” he explained. “This feature will go commercial at K.”
Another trend is that of inline mono-oriented films. “With the discussion about the circular economy and the recycling and reuse of materials, mono-material packaging solutions are needed. As a result, recipes are moving towards 5 layers rather than 3. Inline stretching with Ultra Stretch is an important tool – we have now developed a 5-layer film line for producing a pure PE pouch, for easy recycling.”
“Every few years, we take additional steps in output rates,” said Bernd Schroeter, director Product Management. “This new FSS line achieves a rate of over 400 kg per hour, higher than conventional 3-layer film lines, and producing a ‘good’ product.”
What is a good product? According to Schroeter, it is one that can meet the criteria regarding dart drop – the bag won’t burst when dropped – tensile strength, elongation, secant modulus, creep resistance and sealability. “All of which also has to do with the resin and recipes selected – usually with metallocenes – and ambient temperature” he added.
The technology used for this new 5-layer line enables the downgauging of heavy-duty shipping sack films.
“This was achieved through the use of high-performance screws in all the extruders to enable low melt temperatures, providing efficient cooling conditions,” he explained. “This results in cost savings, due to thinner skin layers that require less costly resin and additives and less expensive resins – such as recycled material – in the core layer.”
The layers of the film produced during the event at KZPM consisted of outer skins of LLDPE, and mLLDEP, with a core of recycled HDPE. The resins used for this recipe were provided by Sabic.
According to Schroeter, the mechanical properties of the film were also improved due to the ‘pure’ layers, as less blending is required. “This is important, as it affects dart impact performance,” he noted. A dart performance of over 5 g/µm is achieved with this recipe, which is higher than specified for typical FFS applications. He added that because of the 5-layer structure, recycled resin could be used without any perceptible impact of film performance. “No migration of additives is possible into the skin layers due to the barrier provided by the subskin layer,” he explained.
The result: more flexibility in film recipes, and improved film properties because of the clean outer layers.
“Immediate leverage,” he said, adding: “It is a development we made, not in response to demand from our customers, but from the end users.”