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Recyclability in the bag

Dean Gianni, MD of Packaging World, explains that the new patented, rough to the hand, Paper Touch bag – which ensures that Woolworths retains a kraft paper look – required new technologies on all levels, from the cast polypropylene (PP) construction of the film, which ensures that the oils don’t leak, to the printing plates, inks and aniloxes used. 

‘We searched for cast PP film suppliers from China to India, the UAE and Europe and were fortunate enough to find the right supplier willing to work with us,’ Dean notes. ‘We chose this PP construction because it gives us the rigidity and the sealability we are looking for, enables us to put in the necessary barrier properties while maintaining the bag’s recyclability and provides a better look and feel in-store than LDPE alternatives. Although LDPE is currently more recycled in South Africa, PP recycling rates are growing quickly.’

Geoff Cuttler, national sales manager of Flint Group in South Africa, explains that the project team of Dipak Chauhan (national technical manager), Seshen Reddy (key accounts manager), Wesley Jared (applications manager) and Kalvin Shivaraja (in-plant supervisor who manages the inks at Packaging World’s site) has worked with Packaging World on several Paper Touch bag projects for Woolworths and other customers. 

Geoff States: ‘With this project, it was necessary to run trials in Flint Group’s global print and raw material testing laboratory in India. These trials were to confirm the suitability of the cast polypropylene film from the supplier to guarantee ongoing flexibility in Packaging World’s supply chain.

‘We also ran numerous trials in our Durban laboratory to obtain the correct film weight and feel with the tactile/haptic varnish. To achieve the Paper Touch, it is critical that the product runs on press at the right viscosities. If you run at a low viscosity, it will likely rub off and start to powder. On the other hand, if you run at too high a viscosity, you won’t get the Paper Touch feel. It was, therefore, necessary to conduct various drawdowns to get the right end result. Based on those results, we could advise Packaging World on the appropriate high ink transfer aniloxes for running the job on their Windmöller & Hölscher Miraflex II press.’ 

Geoff confirms that press trials went well and that application testing was helpful to ensure success for use on the package. ‘With applications testing insight in hand, we worked with Repro Flex to develop a new plate ensuring correct coverage of the tactile varnish and use of the label in-store.’

Dean adds that although the non-release lacquer uses a lot less ink, the teams hope that ultimately Woolworths will be willing to change from the current paper pricing labels to PP ones. Other in-store tests performed included drop tests, where the bags worked well but the labels didn’t, and taking the rotisserie chickens straight from the oven, putting them into the bags and sealing them and then wrapping them up in a towel to keep them as hot for as long as possible to test their performance. 

The PP bags started making their official in-store appearance in early September and will become more prevalent as soon as the stores have run out of their original paper rotisserie bags. ‘This transition represents significant savings in terms of the amount of packaging used especially because the PP bag doesn’t have to be packed into an extra LPDE bag to prevent leakage,’ Dean reports. ‘In the future, when sufficient capacity has been installed we would like to source the cast polypropylene film locally.’ 

Screening for plate performance excellence

‘Repro Flex supplied new Flint Barbosa photopolymer plates with the latest generation of ThermoflexX Woodpecker surface screening to assist with the dense ink transfer required to achieve the Paper Touch texture,’ says director Jamie O’Neill.

‘The Woodpecker screening controls the ink more accurately as it is transferred from the high ink transfer anilox to the plate and onto the substrate. The result is a smoother, higher opacity ink laydown, sharper line work and cleaner screens, without any of the common printing defects found in flexo printing at full press speed.’ 

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