Comexi, QuadTech tie up for closed-loop colour control
January 12, 2018

Since 2016, Comexi and QuadTech, Inc have joined forces in the investigation and development of new colour control management technologies for the flexible packaging industry. After years of research, this close collaboration between the two companies has pursued the adaptation of QuadTech’s Color Control with SpectralCam, and its extension from paper and label printing to the printing of flexible packaging.

The Color Control with SpectralCam system brings significant advantages for standard applications on various flexible films. The two global enterprises have made progress on increasing brand owners’ awareness about the benefits of this technology.

Early on, Comexi and its Offset Business Unit team recognised the clear advantages that the closed-loop Color Control system brings to press operators and converters in the flexible packaging printing industry. As flexible packaging printing typically runs reel-to-reel, it is not possible for press operators to take a printed sample for exact colour check. That was one of the main requirements that the two companies recognised, and this drove the implementation of Color Control with SpectralCam for flexible packaging printing.

QuadTech’s system brings automated precision for achieving colour targets. Spectral-based, closed-loop colour control means faster, easier color OKs, reduced make-ready time and enhanced productivity. The innovative SpectralCam is a 31-channel spectrophotometer that accurately measures spectral response over micro colour bars, then calculates L*a*b*, ΔE, Density and ΔDensity…all at full press speeds. The patented web stabiliser uses ISO-conforming black and white reference tiles—a constant, known backing—that moves with the camera to provide consistent spectral response. Short bursts of pressurised air are used to bring the substrate into close proximity with the ceramic backing tiles for precise colour measurement. Patented adaptive control methodology adjusts the press to maintain accurate control over four-colour process, extended gamut and spot colours throughout the run.
On Comexi’s Offset CI8 running seven-colour process, also known as “extended gamut’ printing, a spectral system that measures colour is preferred over a density measurement. SpectralCam is QuadTech’s third-generation spectrophotometer.

Manager of R&D for Comexi’s Offset Technology, Adelbert Schoonman, explains the main challenges that the closed-loop Color Control system addresses: “All printing processes have their deviations during a print run. It is of great help for each printer when they can monitor, automatically correct, and regulate the quality of the colours during the process”. In today’s flexible packaging industry, there are various systems on the market that simply measure colour or density inline, and then show the colour variations in a graphical or numerical way to the printer. These systems do not then “close the loop” by also automatically making colour adjustments. Also, when required, the printer can react on the provided information during the run, for example by making adjustments to viscosity, temperature or pressure”. In comparison to flexographic and gravure technologies, offset printing technology offers an additional parameter that can be used in order to control colour consistency automatically, without operator intervention.

2451a-760x566 Real-time display of important print
Real-time display of important print attributes arms press operators with valuable information to assess product quality and press performance.

Ink fountains of offset presses have a range of narrow ink keys across their entire width. The opening of each individual ink key can be remotely controlled by the operator, in this way the operator can react on local or general colour variations, as they are indicated by the colour measuring systems. The ‘closed-loop’ Color Control system can make the press operator’s corrections by automatically adjusting the ink keys based on data provided by the SpectralCam.

As Schoonman explains: “In the paper printing industry, closed-loop control systems are standard equipment with a long history of proven performance and, nowadays, are standard equipment on many heat-set and cold-set web presses. However, the characteristics required in the flexible packaging printing, such as measuring through a transparent film, and the different characteristics of packaging films—like clarity, gloss or matte finishes, background or spot colours—makes closed-loop colour control for flexible packaging much more challenging”.

With SpectralCam in combination with the advanced web stabiliser system that assures a stable and calibrated background for each measurement, QuadTech and Comexi deliver an important part of the required solution. “Thanks to the collaboration between QuadTech and Comexi, we are working together to introduce a closed-loop colour control system that benefits operators and converters and will be of added value for flexible packaging printers using Comexi’s CI8 Offset technology and the whole flexible packaging industry”, states Schoonman.

Comexi and QuadTech will continue efforts focused on creating new developments that bring advantages for standard applications on various flexible films, and are working with brand owners to combine the use of colour patches in flexible packaging designs to increase their understanding and awareness and, at the same time, to create a broader acceptance of this innovative technology in the flexible packaging market.

(January 2018)