How flexography will impact UV-LED curing, barrier coatings & printed electronics — and vice versa

FTA Forum 2013 logoThe Emerging Trends session at last week’s FTA Forum in San Diego once again hit on the top technologies likely to significantly impact flexographic printing in the years ahead. This Converting Curmudgeon bullet-point review covers the presentations on UV-LED curing of inks and coatings (Mike Buystedt of Flint Group); high oxygen-barrier coatings (Bob O’Boyle of Sun Chemical); and printed electronics (Tracy Lunt of DuPont Packaging Graphics). For a closer look at the fourth technology — acoustically-enhanced drying — see the technical paper by Gene Plavnik of Heat Technologies published in the 2011 Q3 issue of CONVERTING QUARTERLY.

UV-LED Curing (ultraviolet light emitting diode)

  • The alternative to traditional mercury-based lamps requires specifically formulated inks offering advantages in operating costs, capabilities and environmental aspects.
  • Compared with arc lamps, UV-LEDs have 10X longer lifetime, are ozone-free, use small input-power units, are instant on/off, need 75% less maintenance, use 50% less energy and generate heat only to 60 deg C, making it film-friendly.
  • Complete UV-LED solution presented at Labelexpo Americas 2012: Two narrow-web presses ran 16W/cm2 UV-LED lamps on UV-LED inks and coatings printed onto BOPP film and semi-gloss PS at 500 fpm and 750 fpm, respectively.
  • Beta-tests and flexo commercial successes include 2-color-plus-coating film label, first 4-color process label on semi-gloss material, first 6-color shrink label on PVC film, first unsupported film lamination, first 3-color semi-gloss paper with overlaminate, and first direct-thermal label — UV-LED curing did not activate the coating.
  • Quantifying values via UV-LED: 14% more yield through less maintenance, less lamp degradation and instant on/off. Also 15% faster production speeds due to cure efficiency, less lamp contamination, and deeper/better cure.
  • ROI summary vs. mercury lamps: $6,600+ monthly savings in capital expenditure, energy and maintenance. Seven-month payback if mercury units already in place.

High Oxygen-Barrier Coatings

  • Early problems with instabilities and poor coverage with nanoparticles in coatings have been for the most part eliminated with improved formulations and press techniques.
  • Finely dispersed nanoparticulate silicate provides a functional oxygen barrier of <0.06 cm2/100 in.2/24h at 50% RH on PET film.
  • Applications as replacement for PVdC and EVOH in flexible packaging and to enhance or replace metallized, AlOx and SiOx structures.
  • Printed via flexography, gravure or roller-coating processes, nano-clay materials are often supplied in two or more parts that must be mixed prior to use. Newest versions are now available as one-part materials, easing application.
  • Approximately 25% of the volume of the anilox transfers onto the substrate; films need corona treatment before coating to enhance adhesion and lamination bond strength.
  • Market-value propositions: Chlorine-free, enables lightweighting, improves sustainability, transparent barrier, eases recycling, and cuts expensive barrier films.
  • Processing-value propositions: Can be applied on existing equipment at conventional film weights, enables removal of barrier film and adhesive in 3-ply-plus laminates, cuts waste and energy use, and allows duplex laminates to compete with triplex.

Printed Electronics

  • Additive process can allow printing of RFIDs, sensors, thin-film batteries, retail security items, OLED lighting, re-writable memory, flexible displays and photovoltaics.
  • Flexographic-printing capability at Topflight on flexible paper and film has achieved variable conductivity of 250,000 – 0.005 Ohms/sq. Two different anilox volumes to vary thickness of conductive traces.
  • Topflight Space Saver concept: 4×4 pattern of 4-mil-wide lines and spaces flexo-printed with conductive silver nanoparticle inks on film (320 fpm) and paper (220 fpm) achieved 1284 Ohms/sq; used 70% less space than 10×10 pattern; compares to only 30 fpm on rotary screen printing for thick film.
  • California Polytechnic Institute research shows 6.35-micron line-holding capability with flexo at 8,000 dpi. Clemson University research flexo-printed a transparent conductive grid with 25-micron vertical lines, 30-micron diagonal lines at 200 fpm.
  • Significant advances happening constantly in inks, substrates, designs. True system integration of design, printing and plates still in progress.
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