MATERIALS | STRETCH & SHRINK FILM
Right: CJ Bio has introduced two PHA-based compounds for blown, cast and MDO film applications
In a second example, Italian flexpack manufac-
turer Plastotecnica made a product changeover on a seven-layer stretch film line. Using Mastermind helped it cut daily scrap from around 2800 lbs to 800 lbs – in both the production change and through die lip cleaning. Over the year, this amounted to nearly 700,000 lbs – around US$400,000 in monetary terms. Using Mastermind meant that operators no longer needed to adjust die bolts to adjust the die lip – re- ducing waste that had been generated before.
Pellet avoidance Robert Wahlmueller, CEO of Erema North America, told delegates that the typical method of recycling waste material – using re-pelletised material – can be avoided. He said that the company’s machinery can be incorporated directly into the production line. This allows it to gently melt production waste – such as edge trim – and feed it directly back into the production process. This inline processing of edge trim means no degassing, no melt filter – as it is clean in-house material – and can have an output of 250-600 kg/ hour.
However, post-commercial waste (from super-
markets) and post-consumer waste can also be recycled. The main challenges of recycling post-supermar-
ket film are humidity (due to outside storage) and contamination (such as from paper labels). Erema first pre-conditions this waste, which performs several functions – including cutting, homogenising, heating and compacting. This moves to a gentle melting process in a short extruder, which ensures that contaminants are not carbonised. These are taken through a two-stage filtration process. The company says its DualFil process can consume around 10% less energy – and run around 18°C cooler – than existing double filtration methods. This helps to raise throughput by 5-10%, he said.
Double bubble More recently, at AMI’s European stretch and shrink film conference in Valencia, Spain, Lin Kai Kai, sales manager at Shantou Mingca
Packing, said the company had developed a non-crosslinked recyclable polyethylene shrink film, which uses ExxonMobil low-density Exceed XP material. Lin explained that the film is a mono-PE solution
created using double-bubble technology on a downward, water-cooled blown film line. The film has been tested at ExxonMobil’s
18 FILM & SHEET EXTRUSION | June 2024
technology centre in Shanghai to assess its tensile properties, mechanical strength, haze, gloss and other attributes. It found a tensile strength of more than 100MPa, and an elongation that was greater than that of standard polyolefin shrink film and equivalent puncture performance. It can shrink more than 70% on heating to allow shrink performance at lower temperatures (135- 150°C). Thanks to this capability, it can offer potential cost savings due to the shrink tunnel – consuming less energy than what is needed with conventional solutions, says the company. In addition, it had relatively low haze (2.8%) and high gloss (up to 86 GU). The company will make the film available in
Europe, North America and China in 2024, then attempt to raise demand as high as 10,000 tonnes/ year in 2025
PHA formulations Hugo Vuurens, VP of business development at CJ Biomaterials, said the company offers a number of formulations to make shrink film from its amor- phous polyhydroxyalkanoate (PHA). Its PHA is produced by bacterial fermentation.
The material – called PHACT A1000P – is biodegrad- able in home composting systems. When blended with PLA, it can lead to stronger films – with higher tear-resistance – that also degrade more quickly. Two compounds – CA1270P AND CA1240F – are blends of PHA and PLA, used for blown, cast and MDO/biaxial film applications. CA1270P is a transparent, unfilled grade, while CA1240F
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IMAGE: CJ BIO
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