Offset Printing
UV printing opens up attractive new business options
Monday 04. February 2008 - UV study group at 2008 print forum
At the Stuttgart Print Forum on 28 January the member companies of a UV study group gave a joint presentation for the first time on the new business opportunities afforded by UV print production. The BGDP, Germanys industrial safety council for the printing and paper processing industry, provided a comprehensive review of the safety issues relating to print chemistry and technology, Fogra discussed process standardisation in UV offset while KBA, HDM and MAN focused on the potential for optimisation, process stability and standardisation in UV offset.
The second part of the event examined application-specific productivity gains with optimised UV radiation technology (IST Metz), inline finishing trends in sheetfed offset (KBA), new opportunities afforded by waterless UV offset (Druck und Beratung Braun/EWPA), and waterless UV offset in B3 (21in) format (Herrmann Druck+Media, Sonnenbühl).
Profit and stability
The forum was chaired by the BGDPs consumables expert Dr Bernhard Küter, who started by reviewing the parameters required for UV technology, the environmental and safety issues involved, and process stability. The UV study group, which was set up by the BGDP and has 49 member companies drawn from the printing and supplies industry, research institutes, teaching professions and trade associations, has published a UV protocol for all current printing processes. The protocol is available in English or German.
Speaking on behalf of the BGDP, which provides accident insurance for the German printing and finishing sectors, Dr Küter stated unequivocally that “UV printing is not a health and safety hazard.” He added that the safety council, whose norms have become global standards, will continue to keep a weather eye on UV technology and take action whenever justified for health, safety and – more important than ever – environmental reasons.
Advances towards standardising UV offset
Dr Wolfgang Rauh, head of chemistry and the environment at Fogra, gave a run-down on production conditions at UV offset printing plants. The object is to maximise printing speed, minimise control and regulating tasks at the press, detect and remedy the causes of corrosion, and to address customer demands for certified offset standards accreditation similar to that for conventional inking systems.
But before UV offset can be standardised it must be optimised – firstly to define the impact of consumables on press components and secondly to assess the technical properties of these consumables. In this respect, a stable printing process at high press speeds can deliver genuine cost savings. Test specs for washes, fount solution and inks are already available, compatibility tests for rubber blankets are currently being drawn up, and plate tests will follow. Washes and fount solutions that have passed these tests will be accredited and listed on Fogras website.
KBA and Heidelberg have collaborated on tests and threshold values for the compatibility of inks with various press components. Ink manufacturers whose inks come up to scratch receive a seal of approval and are included among those recommended by Fogra and press manufacturers. A Fogra study on corrosion in UV presses is nearing completion, while others on the odours emitted by UV prints and the sensitivity of UV inks are still being conducted.
Optimisation potential and process stability in UV offset
KBAs sheetfed marketing manager Jürgen Veil pinpointed the aspects of UV offset where there is still considerable potential for improvement. He noted that there are still no specified parameters for proofing forms during press acceptance, proofs with or without interdeck UV dryers, the number of lamps, the definition of substrates, and proofing speed. Nor are there standardised specifications for hybrid and UV offset inks with regard to colour and transparency (ISO 2846-1), norm compliance, tolerance thresholds for full-solid primary colours red (M+Y), green (C+Y) and blue (C+M): only reference values in a CIELAB colour gamut are available. According to Veil, all variables impacting on process stability need to be examined. These include fount solution tolerances; dampening additives, their interaction and their reaction with washes; a definition of materials compatibility; and blanket swelling, changes in volume and suitability for mixed production.
KBA has been awarded BGDP “Emission tested” certificates for all its small-, medium- and large-format Rapidas from the 74 to the 162a. The most recent test completed was on compliance with the basic regulations for optimised handling in UV print production in accordance with the Occupational Health and Safety Standard OHSAS 18001. The certificate, for KBAs demo centre, training centre and experimental press room in Radebeul, was presented by Dr Küter to Jürgen Veil at the print forum. KBA is the first press manufacturer to achieve OHSAS 18001 accreditation.
Joint declaration
A high point of the evening was the signing of a joint declaration by KBA, Heidelberg and MAN Roland to draw up, define and introduce universal standards in accordance with mandatory test specifications for the accreditation of UV and hybrid inks, proofing forms and proofing norms for UV and hybrid inks, and press-compliant auxiliaries and aids, along with standards for enhancing press reliability and user benefits through the use of press-compliant auxiliaries and aids (protection through precise definition). Manufacturers of consumables and aids are voluntarily bearing the cost of accreditation.
UV systems as a basis for wide-ranging coating options
Stefan Feil of IST Metz discussed ways to boost productivity with UV production in conjunction with inline coating and die-cutting. Combining different processes such as screen, flexo and offset printing with inline cold-foil stamping and die-cutting substantially enhance production flexibility. Irrespective of the process employed, UV technology delivers a number of benefits, not least the ability to print on non-absorbent substrates and use solvent-free inks and coatings. Others include instant curing and finishing, high-gloss coatings and abrasion resistance.
For example, in a label printing press with a rated speed of around 100m/min, the curing speed is 80ms, in a 15,000sph B1 (40in) press it is 40ms, in a 300m/min wide web press it is 30ms and in special presses that run at 500m/min it is just 20ms. By comparison a blink of an eye takes around 350ms.
Spiralling energy costs demand energy-saving systems, efficiency gains and optimised UV lamps with chokes and controllable output, and improved housings with reflectors and shutters. Modular systems can best be adapted to customers heat management specs.
Inline finishing trends in sheetfed offset
In his second presentation Jürgen Veil of KBA described the manifold inline coating options possible, which are illustrated in a new sample book that KBA is bringing out prior to Drupa 2008. 48 print samples complete with technical specs, a list of consumables and aids, and details of the production process provide creative professionals and printers alike with the tools for implementing their ideas. Image quality can be checked against reference fields.
Whether prints are finished inline via die-cutting in the coater, ultra-fine kiss cutting (with optional extraction) after the coater or high-quality stamping, Veil sees no end in sight to the current trend. Combining UV technology and brand protection opens up new business lines, and handy tips on making the most of this can be found in the latest issue (no. 4) of KBAs technology magazine, Process. Topics range from the optical and surface properties of the various coating types available to the applications possible and recommended anilox rollers.
Switching to waterless UV offset
Detlef Braun of Druck and Beratung/EWPA answered the question “Is waterless UV offset complicated?” with a resounding No! Though newcomers to the process do need a certain amount of technical expertise if they are to come up to speed without wasting costly synthetic substrates. Press operators must be shown how to adjust the rollers, clean the plates, select the right temperature and set the power output of the UV lamps for the inks and substrates used.
Over the past four years, UV printing has grown from 3% to more than 15% of the market. According to the BGDP, waterless UV offset is the greenest and most efficient offset process – witness the “Emission Reduced Waterless Offset” seal of approval it has been awarded.
Helmut Herrmann of Herrmann Druck+Media in Sonnenbühl runs a waterless B3 (21in) UV press fitted with a UV dryer plus mobile interdeck UV dryers, an inline UV coater that can also be used for spot coatings, and an inline die-cutter with magnetic dies.
Film printing and waterless technology are an ideal combination. Quality benefits lie in the precise reproduction of ultra-fine details and screens, intensive colour brilliance and higher colour densities, maximum light-fastness and the absence of pollution from wiper water additives.
Herrmann Druck+Medias systematically created print samples allow prints to be simulated without the expense of proofs.