DuPont Executive Outlook
Shyamal Desai Americas Marketing Manager DuPont Advanced Printing
Ge ng a good white ink laydown for an under layer has always been a challenge for the flexible packaging industry. A white ink underlayer is key because it forms the foundaon for the graphics printed on the packaging. A poor white underlay er will not give you the desired pop or convey the intended brand message. When white ink is de posited onto the substrate, it does not load well or disperse uniformly. Depending on various in teracons of surface energy between the ink, the substrate, as well as the prinng plates used, you will get a white ink laydown that may appear moled with a poor ink laydown. To address this problem, some printers use very high volume aniloxes to get as much ink on the substrate as they can. Others are using substrates that are im pregnated with white ink — both choices are a costly substute for the ability to print a good white underlayer. What has also been a challenge is understand ing an effective way to measure the white ink laydown. The industry uses opacity as a mea sure to evaluate the ink laydown, however, opacity alone doesn’t give you the full picture. A substrate may have more ink, but if the ink doesn’t lay down well and shows mottling or graininess, it still doesn’t serve the purpose of having a good white underlayer. The ideal solu tion would be a measure that combines graini ness, opacity and mottle into a single number. Less than 80 years ago, the industry faced a similar challenge when working to establish the correct way to measure color. Color measure
ment has evolved over me to mimic how the human eye perceives color. The cones in the eye look at color smuli in terms of red, green and blue. The brain then processes these smuli and forms a color impression or a color percepon. This percepon is formed by linking these three colors with the opcal characteriscs of the printed surface. The challenge results in that this percepon is subjecve and in order to accu rately translate the color percepon into some thing measurable, the fields of colorimetry and chromacity were developed. Color measure ment started off as unidimen sional measurements, unl a muldimensional L*a*b* mea surement system was devel oped to account for not only colors, but also the lightness and darkness asso ciated with it. A similar challenge exists with understanding white ink laydown and white measurement must proceed through a similar evolution as color measurement. Mottle and graininess are measures critical to the overall white impres sion or perception. They give us a view of pin holing and smoothness of the ink. A sample can have a lower opacity, but coupled with low graininess and low mottle, the visual impact is much superior. Therefore, to evaluate white opacity, you need to combine opacity, graini ness and mottle into a single number, which can more accurately give you a quantitative mea sure of white ink laydown.
12 Executive Outlook Flexo Market News
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