MATERIALS | MULTI-LAYER PACKAGING
For PCR-based films, he said
the premium was 3-10%. “You can reduce or eliminate
the increase with changes to the packaging,” he said – citing one bag with 30% PCR that ended up being “almost cost neutral” as the customer downgauged and removed the zipper. There are still many challenges in multi-material recycling, he said, including: industrial sorters not being sophisticated enough to sort flexible packaging; recycling infrastructure continu- ing to lack funding – and being outdated; and, ink, additives and adhesives in multi-layer films making recycling difficult.
Above: Emerald has created fresh produce packaging that contains up to 30% recyclate
Recycled resins US-based Envision Plastics said that its recycled resins – including HDPE and PP – are routinely used in new flexpack products – including food packag- ing. Examples include cereal bags, bakery sheets and shrink film, as well as many non-food packag- ing products. However, the task of making film and sheet from
recyclate has some challenges. “Normal contaminants in the PCR stream can uniquely impact film and sheet converters,” said Jean Bina, director of sales and marketing at Envision.
She said that multi-layer film will often contain
‘gels’. A common layer construction can include degraded PE, PE with silica filler particles, HDPE layers with TiO2
, or layers with PE and SiO2 . . Micro-
FTIR analysis shows each gel contains a micro-parti- cle contaminant, with each particle located within the second layer made of HDPE and TiO2
The company carried out an analysis of embed- ded contaminants. In a study of six samples, three showed LDPE and a potential ‘black phosphate- like’ material. The other three samples were different to each other – showing variously LDPE, cellulose and lignin contamination. The company was able to overcome problems by using a compatibilizer – which helped to remove gels and improve clarity. Modifying processing conditions – such as by maximising filtration – can also prevent contamination, she said.
Mono materials Aldo Mortara, commercial director at Brazil-based Vitopel, said his company has adopted many
16 FILM & SHEET EXTRUSION | September 2024
mono-material designs in order to improve packaging recyclability. In one case, it has replaced PET-based, multi-material structures with polyole- fin-only versions. “Former structures, using PET and polyolefins,
were hard to handle in mechanical recycling so had a low value,” he said. “The presence of oxygen in [chemical recycling] reduced output and increased the carbon footprint of the process.” The new structures use BOPP – which have optimised thermal resistance – and PE. “The polyolefin structure is recycling-friendly and consumes less energy – because of the lower temperature of the sealing jaws,” he added. This principle has been used for modified
atmosphere packaging (MAP) for products such as nuts. Here, a water and oxygen barrier is also needed. In addition, Vitopel has devised new coffee packaging – replacing a structure of BOPET, aluminium foil and PE with a new one that uses BOPP, metallised BOPP and PE. This achieves the correct level of barrier while being easier to recycle.
Top coat
Omar Gonzalez, regional development manager of Mexico-based Oben, said it uses a top-coating technology to enhance film quality. He said that Mexico is projected to see a CAGR
of up to 5% in the use of flexible packaging, in markets such as food and beauty products. There is also growing demand for pet food, protein and resealable packaging, he said. Oben’s top coating technology can handle film in 2.5 widths. The operation – Oben Earth Products – is based in Peru and uses water-based coatings to boost film properties such as barrier, appearance and sealability. It can be applied to a wide range of substrates including BOPP, BOPET and BOPA. The company has also developed products
using recyclate – including BOPET with PCR content. Here, mechanically recycled PET is incorporated into news films. “We replace up to 80% of virgin resin,” he said.
“There is no trade-off in film performance. PCR is encapsulated in the core layer.” It also offers a line of BOPA films that are made
from 100% recyclate. Future moves
As with all ‘new solutions’, there are always difficul- ties when replacing established technologies. “For 50 years, OPP and PET have dominated the print web market, but then sustainability hit – and mixed material recycling is hard,” said David
www.filmandsheet.com
IMAGE: EMERALD PACKAGING
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