FLEXIBLE PACKAGING | TECHNOLOGY
tion and precipitation of polyolefins from multilayer films. Dissolution is considered to be useful for recycling PCR multilayer films which are not suitable for mechanical recycling. An advantage of dissolu- tion is that it selectively recovers polyolefins, while all other materials, colorants and impurities are removed. The resulting polyolefins can then be recompounded and used in high quality packaging. Reported at the CIMPA final event, the TNO Mobius dissolution process was successfully demonstrated in the project at TRL4 (a high quality white polyolefin product was recovered with a high process yield) and which could be scaled up at TRL5 (at kg scale). Product analysis showed that all non-polyolefin materials were removed, including the majority of stabilisers. The product should therefore be recompounded with the addition of stabilisers.
process. […] The MNL, in its basic configuration, involves initially the same procedure as cast film coextrusion, merging two different materials, coming each from one extruder, into a feed block. Afterwards, the resultant bilayer system is [led] to a multiplier unit, consisting of a series of multiplier elements each one being capable of splitting the incoming flux and remerging it, and thus, increas- ing the number of layers in an exponential way along the whole unit, according to: Number of layers = 2n
+1
where n is the number of multiplier elements.” In addition to CIMPA’s mechanical recycling
work, physical recycling processes were investigat- ed by research group TNO, based on the dissolu-
Film extrusion A collaboration between film extrusion technology group Colines, melt filter specialist Gneuss and ExxonMobil Signature Polymers aims to help film manufacturers produce high-quality PE film when using PCR material. They have worked together to minimise the gels and black dots that can occur in film with PCR content. ExxonMobil technical experts have conducted trials using PCR material derived from stretch film in combination with the company’s Exceed Tough m 3812 high perfor- mance PE and observed a reduction in the size of the larger polymer gels. Bart Lauwers, Principal Extrusion Customer &
Application Development at ExxonMobil Technol- ogy Group, said: “With most of the commercial
Left: Gneuss RSFgenius filtration system in operation at Colines’ technical centre in Italy
sweeu.sally@
hotmail.com
IMAGE: GNEUSS
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