Bottle up

A newly developed continuous inkjet printing system can print onto condensation-covered cold filled-drinks containers, even in humid conditions, according to its UK designers.

Cambridgeshire-based Linx Printing Technologies specialises in solutions for high-speed wet bottling lines using glass, PET or PLA containers.

The company said feedback from its customers suggested that some inks give a poor-quality printed code for a variety of reasons: because the ink quality was bad; because moisture behind the code prevented it from being applied properly; or because the instant the bottles were chilled down again, as happens with beverages in glass or PET containers, the code became easily removable.

Linx set out to develop an ink formula that adheres instantly, tolerates a surface that starts off slightly moist and can withstand getting wet again after drying.

Like all continuous inkjet inks, Linx’s ‘black versatile beverage ink 1058’ is made up of: a solvent base, resins that balance the ability to have a charge applied, conductivity salts to accept the charge and other chemical additives. The methyl-ethyl ketone (MEK) base allows the ink to dry within one-to-two seconds of being applied.

Dr Nick Scott, Linx product manager for inks and accessories, said: ‘What’s different about ours is a highly adhesive resin chemistry that will penetrate a thin film of moisture. We also control the printing micro-climate using specially designed air-knives, which in registration with the printing head give a highly controlled drying process to dry the surface just as we print. So in a way we cheat a bit.’

Air knives are commonly used in bottling lines, but are added to the line as a bespoke fabrication. Linx claims it is the first to package them as a standard element on the printer (the Linx 4900BC) rather than a separate engineering product, reducing the degrees of freedom between the drying and printing process.

‘When installed as a separate element to get the water off the surface, sometimes the air knife will be so far away from the printer in the humid environments where the cold filling is being done, we’d find that the moisture film would have replenished itself by the time we came to print,’ added Scott.

The 20kg printer has a stainless-steel casing with IP55 environmental protection rating, meaning that it can withstand dust and waterjet washdowns as required in food and drink production. It has a built in user interface, with an option to operate it by remote control.

According to Linx, the ink sticks so thoroughly it can only be removed in caustic bottle-washers prior to reuse or recycling. Linx has been working on this system since 2000 — the new printer is based on a previous version manufactured without the air knives. Though good results were easy to achieve in northern Europe, one of the biggest challenges was overcoming the additional humidity in hotter environments, such as bottling plants in the Philippines. The company said the technical breakthrough came a year and a half ago and the package has just been launched.

According to Scott, the latest solution rises to any moist-bottle challenge in bottling plants that operate around the clock. ‘The notion means for the first time we are controlling the micro-environment just at the point we print, by using a highly controlled air-knife set-up,’ he said.

It could also reduce energy consumption and save money for manufacturers, he claimed. ‘You can fire a huge amount of air at the surface from a couple of metres upstream, but compressed air is one of the biggest costs in a factory,’ said Scott. ‘We’ve tuned and minimised, finding a robust space for us to work in whereby by having only two nozzles and limited pressure, we cut down on people’s compressed-air costs.’