MATERIALS | PLASTIC POUCHES
Right: Saperatec has used PCR materials to create non- food flexible packaging
ultrasonic welding turns on instantly and consumes energy only during sealing – leading to a reduction of around 75% in energy costs. The company says that because ultrasonic
generates heat internally, there is a lower risk of melting the carrier layer. Precise control of energy leads to a smaller process window. Sticking with sealing, Ton Knipscheer, sales
director at Watttron in Germany, explained how ‘digital sealing’ can help reach sustainabil- ity targets. The technology sees the classic seal bar – which has a single heat pipe and no tempera- ture control – replaced with a ‘digital seal bar’ that has an array of controllable heaters. This means that different products – such as a pillow bag with side gussets, and a pillow bag – can be heated differently. In digital sealing, only the surface is heated, and
it heats up much more rapidly. This saves both process time and energy, he said. A comparison of energy consumption showed that it reduced the energy used in the heat-up phase by nearly 95%, and cut sealing energy in half.
Coated pouch Tarquin Crouch, head of materials at Applied Materials, explained how vacuum coating of pouches can help to improve sustainability. The company develops roll-to-roll coating systems using a number of technologies including metallic deposition, e-beam evaporation and magnetron sputtering. “Polyolefin flexpack structures are the main focus for recyclability and development – and these are vacuum-coating friendly,” he said. The company has developed a recyclable retort pouch in collaboration with Brueckner and Mitsui Chemical. Retort pouches are the most demanding volume application in flexpack, he said. They are currently made from “complex mixed materials” including PP, PET PA and foil. The aim here was to eliminate aluminium foil and move to a mono- material design for recyclability. It involved coating thermally stable, high-barrier BOPP film with aluminium oxide or silicon oxide using vacuum coating. The film was made on Brueckner machinery – in- cluding its Lisim biaxial stretching technology – us- ing highly crystalline PP resin. Applied Materials tried a number of coatings before settling on SiOx – which was applied using a Topbeam 2850 EB evaporation system. This melts or sublimates the target material in a crucible to create a plume of atoms – which are deposited as a coating. Mitsui’s
40 FILM & SHEET EXTRUSION | July/August 2023
IMAGE: SAPERATEC
Takelac WPB series is used as a topcoat. “We are looking for commercial converter
partners to engage in beta-testing and commer- cialisation,” said Crouch. Other applications include: an all-PE pouch,
using AlOx and SiOx, made with Henkel; a bio- based pouch that coats a paper/PEF/bio-based PE film with AlOx; and a BOPE mono-material pouch coated with AlOx – without needing a topcoat.
Delamination recycling Dennis Meisel, an R&D chemist at Saperatec, gave delegates an update on the mechanical recycling of metal barrier flexible materials. “The low recycling performance of flexible
packaging must be significantly improved,” he said. He said the aluminium foil is often still the best barrier to oxygen and water. And, while aluminium- plastic packaging can be sorted effectively for recycling, the plastic is not often recovered. Saperatec has developed delamination recy- cling for multi-layer composite materials. It has been tested in a Saperatec pilot plant since 2014 for a wide range of applications, he said. “We’re on track to commission our first commer- cial composite packaging waste recycling plant in 2023,” he said. The technique is based on a new method for
recycling aluminium-based composites, which uses hot washing to separate the aluminium parts from the plastic.
It has also begun projects to delaminate
products such as aluminium-PVC packaging, metal-polymer composites and aluminium-plastic pipes and panels. Materials are pre-conditioned for delamination
by cutting, fibre reduction and contaminant removal. After delamination, the materials are sorted into polyolefins, high-density plastics and aluminium. The polyolefin fractions are nearly free
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