06/2007
UV TIME!

GIDUE as a renowned UV flexo press manufacturer, recently entering the offset world, strongly believes that UV flexo has completed its trajectory towards high quality and productivity. It can now be considered a mature printing technology, able to compete with the long established tradition of offset and gravure.


GIDUE’s challenge is to take in-line UV flexo beyond its current boundaries both in terms of potential and end products coverage. The GIDUE objective is to make UV flexography the technology of choice for the strictest and demanding market: the perennial evolving and fast growing food packaging industry?


Food packaging, not differently from packaging in general, dictates its rules very firmly: eye-catching look is a must (the packaging appeal is surpassing the interest in the content), colour stability and predictability, full-quality repeatability, flexibility in materials used, cost-efficiency and most importantly hygiene and safety of the packaged product.


UV flexo technology is based on the principle of polymerization (curing), opposed to ink evaporation, with great success in terms of quality of the working environment, of safety for the company and the workers, as no solvents are involved, and in stability of the printing process. Consistency during production and lower dot gain are additional non-negligible plus. UV inks ensure full curing and a consistently high adhesion to any substrate. About colour stability only the UV flexo technology can guarantee a narrow window of tolerance in changes of colour hue and density even in the most demanding environmental temperature and humidity conditions. Additionally, UV flexo inks do not evaporate, do not change density, do not need additives and do not dry on the plates, thus reducing the time for cleaning.


Flexo can print high quality processes, solids, varnishes and screen-simulating effects, with an excellent management of frequent ink changes; the same job can be repeated many times with no change in the printed result, irrespective of the operator. Set-up times are extremely short thanks to the fact that UV flexo inks print immediately with less waste. UV flexo is extremely flexible and ensures repeatability under global standards; it is versatile on practically any substrate and cost-efficient. Furthermore, less experienced operators easily become competent using UV flexo inks, as the level of skills needed are significantly lower than those needed when using solvents or water-based inks.


The challenges of the Food Packaging industry


The ITX case that boomed in 2005 in Italy toured the world. A laboratory found a migration of ITX material (Isopropylthioxanthone, a radical molecule responsible for polymerization) into a major brand liquid infant formula. The company rapidly informed that ITX was not a substance used by the packaging industry as a whole and confirmed that ITX found in the milk did not represent a health risk (later on confirmed by EFSA, see next), but nonetheless stopped packaging the milk with the material affected by ITX and started replacing the stocks in Europe with products packed with an alternative material. Debates and uncontrolled alarms followed. It is not our intention to cover these details here; what is most important is that the possible danger, even the evidence of it, came to the attention of everyone.


Before and especially after the ITX case, both the Food and Drugs Administration (FDA) in US and the EC issued strict standards for food packaging, mainly regulating the “indirect food contact” of printed packaging (not directly in touch with food) and with a slight chance to get in accidental contact. Migration is the chemical contamination of food, resulting in the worst cases in the toxicity of the food itself, or, in minor cases, in a distorted sensorial perception. The FDA establishes the maximum migration rate, which a human can accumulate daily: less than 0,5 ppb – parts per billion - with no toxic results, under 50 ppb with two favourable toxicity tests, and less than 1000 ppb with three favourable tests and two sub-chronic oral studies (in which the tested substance is administered orally to a testing group in daily doses). Taste and odour must not alter the organoleptic properties.


Generally speaking, the Directive 1935/2004 is clear when stating that migration must not represent a risk to human health, that no change in the food composition or in the organoleptic perception is acceptable. Food packaging must be odour-free, that is to say be compliant with the so-called Robinson test ranging from 0 (no odour) to 5 (strong odour). The sensorial issue is the most difficult to measure as odours (and tastes) are perceived differently from person to person.


The European Commission has created EFSA, the European Authority for Food Safety, in 2002 to evaluate the toxicological risk of substances and facilitate communication among producers and institutions. The EFSA publishes a list of substances which must undergo specific migration limits and sets ranges for the unlisted ones: less than 10 ppb in case of no toxic results, under 50 ppb with three favourable mutagenic tests, or more than 50 ppb in case of presence of favourable toxic results. The most recently issued EC Directive 2023/2006 states that the materials and objects bound to touch food must be produced under “good manufacturing practices” (GMP). This is again the case of packaging printed and stored in rolls for future use where the internal side of the packaging might occasionally get in touch with the printed layer.


Another requirement of the food packaging industry is the elimination of Volatile Organic Compounds (VOC), carried by the substrate and inherent in the working environment. VOC cannot be completely eliminated because of their volatile condition, but the press manufacturers have been introducing advanced treatments aimed at their control.


The standards and the ITX case posed one major problem. The whole food chain, including the chemical industry, the ink producers, the food companies and the packaging manufacturers, are involved in keeping migration levels and danger below the line. Everybody is entitled to know the materials used, be responsible for their manufacturing quality and for their impact on the end products.


We expect new standards related to food packaging to be issued in the near future, finally regulating both ink production and UV use.


It’s UV TIME!™


GIDUE, the leading company at the forefront of research on flexo technology is pleased to offer its customers the most valid solution to either strengthen their position in the food packaging market or enter it anew, in the full knowledge of standards and keeping in mind the food packaging industry constraints and necessities. The GIDUE solution, named UV TIME!™, is based on the principle of polymerization under nitrogen inert atmosphere and aims at offering immediate measurable results in terms both of product quality and safety and in the press overall performance. UV TIME!™ has been designed in cooperation with Air Liquide, one of the major world players in the liquid gas industry, already offering to the printing industry the gas primer coating Aldyne™, a mixture of nitrogen and other gases used, among its many applications, to increase the ink adhesion to plastic films, typically used by the flexible packaging industry.


GIDUE and Air Liquide are already working to certify UV TIME!™ for overall food hygiene. Security of the system and end product safety are the keywords of their combined efforts.


UV TIME!™ is a real breakthrough because unlikely similar solutions which pump the oxygen out substituting it with nitrogen, uses a nitrogen ‘blade’ to break the boundary layer of air transported by the web, so creating a very thin bed of inert atmosphere on the substrate. This inert atmosphere prevents the UV-radiated photo-initiators, which are responsible for ink polymerization, from creating unwanted radical combinations with the oxygen particles carried by the web. The target oxygen presence that allows the elimination of odours and ink migration (less than 50 parts per million – ppm - but close to 30 ppm in reality) is reached with a minimal consumption of nitrogen. UV inks with a lower quantity of expensive photo-initiators in their formulation improve the curing process accuracy and speed (over a certain percentage of photo-initiators UV curing does not take place efficiently anymore even with the most powerful UV lamps).


Ink producers, panelled to discuss the benefits of this technology, admit that a reduction of the photo-initiators percentage in their inks is possible and that the price, after a minimal set of successful installations, could be reduced to even 10 times less. This reduction counterbalances the cost of nitrogen consumption and makes the UV TIME!™ system, the first really cost-efficient UV curing process.


Migration can be controlled to be compliant with standards in use (less than 10 ppb), contemporarily ensuring a clean working environment (ozone-free) and increasing VOC elimination thanks to the reduced layer of air transported by the substrate.


Thanks to a ‘deeper’ and faster curing, heavier layers of ink can be laid on the substrate increasing the opacity effects, ink chemical and scratch resistance, and reducing the thermal stress on the printed material.


The new UV curing system perfectly fits in the machine and is composed of two gas chambers placed right and left of the UV lamp (Gas Seal Kit); the nitrogen flows into the UV reaction zone under the lamp from an injection pipe directly connected to an outdoor gas disposal (leased by Air Liquide) with no real changes in the ergonomics of the press or the working environment. The nitrogen flow is easy to control thanks to a user-friendly gas panel placed near the printing machine and with easy access for the operators who don’t need any special training. The system overall safety is inherent in the system and certified by Air Liquide expertise in the gas industry and GIDUE know-how in the world of flexo.


The benefits for the printer are countless: preserved high printing speed, favoured short-runs and quick job changes and excellent process flexibility. And of course, the certainty of being able to offer customers in the food packaging markets the most valid and winning solution. Furthermore, less powerful lamps are needed, with great benefits in terms of energy consumption, ease of installation and cost of the machine.


UV TIME!™ has been standardised to fit in GIDUE flexo machines range with high retrofitting possibilities.


UV TIME!™ ON ATHENA™ LINE: A PERFECT MATCH


UV TIME™ is offered to the market coupled to the latest GIDUE UV flexo press Athena™ (available widths: from 530 to 730mm), which, with its heavy duty and gearless configuration, is especially designed for the global packaging industry – with wide ranging benefits. The mid web press Athena™ is the ideal response to the new trends in the packaging market as it is an alternative to large web presses featuring an unprecedented level of efficiency and standardisation.


Athena™ is able to print and convert from thin film to heavy laminated board, in fact, practically any web substrate used by the packaging industry. This fully Intelligent mid-web press, has been created and designed to implement the advantages of in-line presses with an open structure – for multiple choices of web path, with a full range of accessories – flexo/gravure printing and ‘Intelligence’ which controls web temperature, register, tension, print pressure, UV and drying adjustments.


In order to avoid resonance effects and to allow correct direction of the forces which create vibrations redirecting them to a controlled area, eliminating disturbance of the printing quality, the print unit of Athena™ has been designed on a completely new triangular configuration, opposed to a 180° in-line, common to presses currently available in the market. This completely new approach is the result of a Finite Elements computer simulation, which has proven to be very successful. The dot gains value measured on the printing unit are the best available in the mid and wide web market. They are identical to those of narrow web presses, even with double the web width and with double printing speeds.


The press is PC-controlled and is able to be Internet connected for remote service. The completely ‘digital’ control on the machine supports the operator with fully automatic adjustments during set up operations (pre-register, automatic register, automatic pressure adjustment, automatic substrate calliper control, automatic tension control) and avoids unnecessary repeated operations. This means greatly reduced waste, as all the parameters of the optimal adjustments are digitally reproduced and only limited set up time is needed. Furthermore on new jobs, the possibility of errors, damaged plates or substrate is greatly reduced, if not eliminated, by the Intelligent Calliper feature. This automatically positions the plate cylinder and the anilox roller to achieve the correct pressure adjustment, relative to the plate thickness and to the substrate calliper, within a tolerance of less than 5 thousands of an mm!


The operator can concentrate on productivity as quality and set-up are taken care of by the Athena™ ‘Intelligence’ (Servo Driven PC Integrated Control). A new term should be used: digital ergonomics. The control ‘depth’ and the flexibility of servo controls on each operation make the retrofit of further software and hardware integrations easy and sustainable, both economically and practically. Special care has been given to the development of the ‘Intelligent’ register control. It has been entirely developed by GIDUE and it is the only register control in the market, which incorporates a unique self-learning feature. The operator is no longer required to set the register control parameters based on the substrate instability to tension and temperature variables. A specially developed algorithm allows the Intelligent Register Control to ‘sense’ the different characteristics of the substrate, based on the different operating conditions (ramp up, ramp down, steady state etc.). The Intelligent Register Control ‘learns’ the needs of the substrate and becomes more or less responsive, based on the different correction requirements. The accuracy of the control over the different operating conditions and the limited waste is unprecedented in any in-line press currently available.


Athena, as a mid-web press, ‘fills the gap’ in the packaging market facing short-runs requirements since it combines the need of customers for a high quality product, typical of wide web, with the innovative approach of narrow-web converters, used to fulfil the needs of the label industry. In addition, the specific knowledge of UV flexo technology, adds a vast set of unprecedented print quality and job management opportunities. The converters strategy is changing and mid-web represents the key to success, as it is standardised, is efficient and allows a better use of existing equipments widening the graphic and converting range capabilities of flexible packaging.


The addition of UV TIME™ to the Intelligence-controlled mid-web press Athena™ takes UV flexography far beyond any expectation, really creating a new trend which in turn takes UV curing to the highest performance limits and as such, represents the first, most complete answer to the needs of brand owners in the packaging industry.

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