OVER the past several years, Bobst has worked with various value chain partners to develop different process solutions for high-barrier mono-material polyolefin laminated structures.

The demand for mono-material packaging structures is growing rapidly to replace conventional multi-layer composite films. The composite films are difficult to recycle because the different layers making up the composite structure need to be separated.

‘One of the projects we are currently working on is a collaboration between Ticinoplast and Plastchim-T (leading producers of blown PE and BOPE, respectively), Sun Chemical for new formulation adhesives and lacquers, and Bobst for the laminating equipment to produce a high-barrier polyethylene (PE) mono-material laminate,’ explains Corrado Periti, lamination process manager at Bobst Italia.

‘PE alone cannot compete with other substrates’ characteristics, so it’s necessary to strengthen the PE’s oxygen barrier, in this instance using a new formulation water-based, high-barrier lacquer as a coating primer. The PE substrate is then gravure printed before it is laminated to a PE substrate with a new formulation high-barrier, solventless adhesive,’ he explains.

Corrado adds that the full process can be implemented in-house because Bobst Italia’s Competence Centre in San Giorgio Monferrato houses all the machines, making it possible to

monitor, test and validate each stage in the facility’s laboratory. The lacquering is tested on the Vision D 850 laminator using a trolley with a pressurised chamber doctor blade. The material is printed on the Master RS 6003 gravure press and laminated on the Nova SX 550.

Another collaboration focuses on testing the optical results and productivity levels of fast-curing adhesives used for the demanding double-barrier film substrate market. According to Corrado, the duplex structure (PETp/PE-EVOH-PE) was successfully laminated at more than 350m/min on both the Vision D 850 and Nova SX 550 laminating machines, delivering excellent wettability and perfect optical appearance, with no bubble formation.

He also reports that mono-material packaging structures are being successfully introduced in the market, especially in segments like snack foods and confectionery, with R&D teams actively working on finding solutions for more end-use segments.

Online Open House

Local market representative Bruce Beswick, MD of Beswick Machinery, adds that during a recent virtual event, Bobst demonstrated how the latest gravure and lamination advances are making flexible packaging printing and converting operations more agile, sustainable and profitable.

The machines showcased during the online Open House, attended by 800 delegates, were the Expert RS 6003 gravure press and Nova D 800 laminator.

According to Bruce, impressive results were achieved using two gravure jobs printed in oneECG, Bobst’s extended colour gamut process that printed the 14-colour jobs (CMYK, nine spot colours and white) with seven fixed process colours, utilising a range of automation features. Additionally, the job changeover was completed in under 14 minutes with just 95m of waste.

The jobs printed during the February Open House were compared to the same jobs printed in January, using a Pantone colour solvent retention test and a colour spectrometer test, which yielded results well within the Delta 2 target range.

Bruce describes the Expert RS 6003 press’s first notable automation feature as the TAPS system for touch-of-a-button pre-register settings with integrated register control. ‘The system is unaffected by incorrect parameter settings and runs independently of the operator’s skill levels and the web path configuration.’

Another time-saving job preparation and changeover feature is the redesigned service-type Flexo Trolley, which can remain on board during printing or be removed after the printing unit has been set up. The operator can also choose to change only the cylinder or the complete trolley with an inking unit, splash guards, printing cylinder and ink tank.

Bruce reports that the lamination job demonstrated on the Nova D 800 – also utilising the Flexo Trolley, flat tunnel design and driven rollers – matched the high-level capabilities of the Expert RS 6003. ‘The job entailed applying a coating of solvent-based adhesive directly to the 8μm alu-foil substrate, and it was processed at 400m/min with flawless optical quality and web handling.’

He also points out the PET-alu-foil substrate combination highlighted the capabilities of this compact laminator to handle complex applications, such as retort pouches, thanks to features usually reserved for higher range machines.

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