process Drupa 2012: Decision in favour of digital printing Process: Issue 85 - June 2012 Durst news for the science and application of inkjet printing

Transcription

1 process Durst news for the science and application of inkjet printing Process: Issue 85 - June 2012 Editorial Drupa 2012: Decision in favour of digital printing News Upper secondary school is named after Julius and Gilbert Durst Installation Flying colours - Europe s first production example of the Durst Rho P10 200, only recently unveiled at the Drupa Exhibition, is already hard at work in Frankfurt. Science & Technology The chemistry of deinking processes Media & Handling Printing corrugated boards and cardboards with Durst Rho flatbed printers simple, reliable, trouble-free Application The Firma Group used a Durst Rho 750 to create the panels for an exhibition in Venice of the photographic work of Ferdinando Ongania Drupa 2012: Decision in favour of digital printing When Drupa 2012 closed its doors on 16 May at hours, it marked the end of another chapter in the history of printing. For the first time the focus of attention was on digital not analogue printing and finishing technology. When questioned, 40% of visitors stated that they were looking for digital printing machines although the subject had not expressly been the focus of the trade fair for the organisers beforehand. Inkjet has thus brought the outsider technology into the heart of the printing industry. The impact of this development on even the leading manufacturers of analogue machines is impressively shown by the agreement on strategic partnerships which Heidelberg, Komori and Manroland concluded with the Landa Corporation during the trade fair. Nanographic printing, a new rapid process for digital printing using water-based nano inks, was presented to the public for the first time at Drupa. The haste with which an, as yet, totally untested technology still in production has been taken up by a number of offset heavyweights at the same time, is rather like an attempt to sprint to catch a train that has already left the station. Elsewhere, the future has already begun highly productive digital sheet-fed and web printers set the agenda for the trade fair in many areas, often integrated into complex workflow environments. It no longer matters whether print jobs are delivered via the Internet ( Web to Print ), via tablets and smart phones or are initiated conventionally. However, alongside the development in printing jobs, inkjet is increasingly leaving paper behind and going into areas that until recently were still thought of as out of bounds to analogue technologies. An example is the continuous inkjet production system for corrugated board, which is based on the Rho 1000 presented by Durst and can print up to 500 m² of corrugated cardboard an hour, then neatly stacked on pallets and already varnished inline. process - Durst news for the science and application of inkjet printing - Issue 85 - June

2 However, the end to automation is still a long way off. Digital cutters and millers have long been standard in the processing of sheet material. Drupa also saw the first solutions for cutting corrugated board by laser. One company presented digital embossing, an embossed type of 3D varnishing as well as coloured and glitter varnishes, which are applied by jets and makes the creation of expensive templates obsolete. Thus high quality personalised packaging can be produced which creates new opportunities for sales. Drupa has clearly shown that automation and digitalisation go hand in hand, and no operator of printing technology can now afford to ignore this. This is currently proving to be true mainly in industrial settings. Here, inkjet printing is proceeding to supplement and in some cases even replace the screen and pad printing which previously dominated for special applications. Over the next few years major growth in the technology is expected in this segment. The Rho IP (Industrial Print) engine was therefore a magnet to visitors in Hall 6. The module can be specifically configured for the application selected by the customer and can be integrated into automated production lines. Applications include printing membrane keyboards, dashboards and small components using UV hardening inks. Just as inkjet printing is catching on in industrial segments, so is the range of usable inks growing. A number of manufacturers displayed new variants of water-based polymer inks which can be used for printing food packaging. New special printer heads are able reliably to print even aggressive fluids and conductive materials. Despite a decline in footfall of 75,500 visitors compared to 2008, according to press releases, some brilliant business transactions were recorded at Drupa The area of digital printing did particularly well because it was not just concepts and visions on display here but saleable products with the proven security of established production capability. process - Durst news for the science and application of inkjet printing - Issue 85 - June

3 News Upper secondary school is named after Julius and Gilbert Durst A celebration was held on Saturday, 12 May 2012, in Brixen following the naming of the vocationally oriented upper secondary school which specialises in economics, graphics and communication (Fachoberschule für Wirtschaft, Graphik und Kommunkation) after the brothers Julius and Gilbert Durst. A particularly warm welcome was extended to the family of the Durst brothers: Eleonore Durst, the wife of Julius, their daughter Philippa Durst, the daughters of Gilbert and Irmgard Durst-Donà, Alice Durst Wintersohle, Evelyn and Irina Durst and Irmgard Durst Donà, the sister of the Durst brothers and their sons Alberto and Mario Donà. Other guests at the celebration included the Regional Councillor Sabina Kasslater Mur, MP Hans Heiss, Director of the Education Authority Peter Höllrigl, School Inspector Eva Brunnbauer, former Director Elionda Dander-Kammerer, Mayor Albert Pürgstaller, Municipal Councillors Magdalena Amhof and Elda Letrari and also the Chairman of Durst Phototechnik and of the Economic Federation of the Southern Tyrol, Christof Oberrauch. The search for a new name for the upper secondary school in Brixen began around a year ago. The renaming was intended to reflect the new direction of the school with its new specialist subjects. The MP and historian Dr. Hans Heiss was entrusted with the search for suitable figures after whom the school could be named. A school must be able to identify with the people it is named after, he or she must be a role model, a point of reference, if you like. That is why the brothers Julius and Gilbert Durst were chosen. They stand for the spirit of innovation, technical know-how, thirst for knowledge, ambition, perseverance, organisational talent, zest for new developments and, above all, hard work. With these key words or virtues in mind, we hope the pupils will thrive in their studies, are the illuminating words of the Director of the Education Authority and Head of Department Dr. Peter Höllrigl. The new core brand of the school, which we hope will be influential in the future, was outlined by Dr. Hans Heiss by referencing six key values, such as new beginnings, creativity, down-to-earthness, teamwork, young people and responsibility. Julius and Gilbert Durst have shown just how far creative and fearless young people can go, said Heiss. Today, a commemorative plaque was presented and will be displayed in the foyer of the school showing the new identity of the school and who it is named after, Julius and Gilbert Durst. Director Dr. Markus Liensberger. The commemorative plaque was printed on glass with the Durst Rho 800 flatbed inkjet printer. From left: Alberto Donà, Evelyn Durst, Alice Durst, Irmgard Durst Donà, Eleonore Durst, Philippa Durst, Irina Durst with her daughter and son. Chairman of Durst Phototechnik, Christof Oberrauch process - Durst news for the science and application of inkjet printing - Issue 85 - June

4 Installation Flying colours Europe s first production example of the Durst Rho P10 200, only recently unveiled at the Drupa Exhibition, is already hard at work in Frankfurt. Jörg Schönbrodt, Managing Director of Brieke GmbH in Frankfurt, is a happy man. For us the Rho P represents a big step forward, we will now be able to serve demanding industrial customers as well. Just two weeks after it was installed in mid April 2012, the new 2.05 m wide UV flatbed printer was running flat out: On the third day of the installation process we had to load a large roll in the evening and print overnight unsupervised, explains the production manager Wolfgang Schäfer. This trial run, under less than ideal conditions, was necessary because the previous machine, a four year old Durst Rho 800 Presto, had had to be dismantled and Brieke risked failing to complete a customer s order on time. Our customers have come to expect us to deliver speed, flexibility and the very best in quality, explained Schäfer, which is why we opted for the Rho P and, judging from the praise heaped upon it, we can only assume that the P passed its test with flying colours. It s pretty speedy too. The data sheet claims a possible top speed of 175 m²/h, but at Brieke they are currently producing the highest quality at a speed of around 20 m²/h in conjunction with white printing and at up to 50 m²/h in six colour mode. From left: Brieke production manager Wolfgang Schäfer and MD Jörg Schönbrodt in front of their new Durst Rho model. The P installed at the firm s Frankfurt plant is the very first example in Europe, there is only one other in the world and that s in the USA. In any case we would find it hard to process any more throughput at the present time, says the MD of this traditionally based company. As well as the Rho P10 200, the three-storey production building in the centre of Frankfurt houses two smaller printers that use water-based inks, two textile machines and a high speed calender. Panels are cut out on a CNC milling table, and three laminators complete the stable of equipment. Finally there is the Durst Lambda 130 Plus, with the serial number 10, which has been generating turnover for Brieke continuously since Delivering the Durst Rho P was handled by a specialist carrier. The first large roll was already being printed overnight at the end of the third day after installation. process - Durst news for the science and application of inkjet printing - Issue 85 - June

5 Installation Longstanding co-operation The company has been a Durst customer ever since the very early days, said Schäfer. We had been working with high performance enlargers from Durst before we received the Lambda and then in 2002 ordered one of the first Rho 160 inkjet printers. The firm still has one of these in its photo lab on the top floor, though it is little used these days. Things were different back then, when Brieke, which was founded in 1904 as a photographic studio, had as many as three horizontal enlargers in operation at any one time. Demand for genuine analogue prints is slowly drying up, according to Schönbrodt, The digital laser photo and the print quality of today s inkjet machines are simply too good. Besides, there are now so many exciting media available for printing directly onto with special UV inks which would have been unthinkable with conventional techniques. The feed gap height on the new Durst Rho P is an impressive 40 mm. A change of business model is nothing new for Brieke. Until the 1960s it was one of the biggest producers of postcards in Frankfurt and the surrounding area. Then when the boom for big photographs came during the seventies, the company was even supplying customers as far away as Australia, not least thanks to its presence at the Frankfurt print fair. Today the firm s staff of 24 produce much material for artists, as witnessed by an exhibition of impressive urban scenes on display in the reception area. There is also a lively demand for high-grade POS material as well as exhibition stands and panels. An obviously satisfied Schönbrodt, said: The Rho P10 200, with its 10 picolitre print heads and a resolution of up to 1,000 dpi, is the ideal solution for us as it is well nigh impossible to detect any print dots with the naked eye, even from very close up. As well as offering fantastic colours, the new generation of inks can also be used indoors without trouble since they are virtually odourless. And when we need some serious speed, the Durst Rho P never fails. For more information on Brieke GmbH visit: Photos: Sonja Angerer except, Brieke GmbH Artists too like what Brieke does with their work, that s why small exhibitions are regularly on show in the reception area process - Durst news for the science and application of inkjet printing - Issue 85 - June

6 Science & Technology The chemistry of deinking processes Introduction The development of pigmented UV inks for inkjet printing has been marked by a number of different trends over recent years. Apart from improvements in adhesion characteristics, the broadening of the colour space and adjustments to increasingly complex printhead geometries with smaller dot sizes, it has been ecological aspects in particular which have attracted increasing attention in recent times. This has meant that odour reduction, the elimination of potentially hazardous substances and improvements in the formulation of inks to avoid risks to the environment, have been the targets for development. These can be considered to have been achieved with pigmented UV inks based on the best technology currently available. In terms of an holistic approach to the life cycle of products involving UV printing, the recycling of these products is now becoming a priority as the next logical step in basic ecological and sustainable thinking - and deinking processes have a central role to play here. Therefore the aim of this article is to throw more light on the details of the chemistry of deinking processes and to outline the necessity of further R&D efforts in this field. Deinking processes In the context of recycling printed paper and cardboard, an essential aim is to remove the printed layers from the substrate as completely as possible and without residues. Although this is easy to say, the complete deinking process which actually has to be carried out needs to take account of (i) the type and quality of the materials to be recycled and (ii) the final quality required. 1 So it is no surprise that some very widely varying technical solutions have been produced for deinking processes, although they usually have the following process stages in common (see also figure 1): 2 1. Pulping: defibring plus separation of ink and other impurities from the substrate. 2. Screening: removal of other non-paper impurities. 3. Flotation: 3 removal of ink. 4. Thickening: thickening of the recycling material (dewatering). 5. Dispersing: dispersion of other impurities as well as ink and pigment residues which have not been separated. 6. Bleaching: brightening of fibres and, if applicable, colour stripping of dyes. Figure 1. Normal process stages in the deinking process (based on ref. [1] and ref. [2]). Deinking chemicals The use of chemicals is unavoidable if the relevant deinking process is to be effective. Usually, deinking chemicals are already added in the pulper so that a combination of mechanical and chemical processes can be applied for defibring and separating the ink and any other impurities from the substrate. If necessary, additional deinking chemicals can also be added beforehand in the flotation cell; there are also certain chemicals that are only used in the dispersing and/or bleaching process. 1,2 Traditionally, the following chemicals are used with alkaline deinking: 1,2 Sodium hydroxide (NaOH) for the hydrolysis of the ink matrix, for separation of ink residues and for fibre swelling. Fatty acids and surfactants for separating the ink from substrates, for dispersion and for foam formation. If applicable, calcium salts that react with fatty acids and act as ink collectors during flotation. Hydrogen peroxide (H 2 O 2 ) for avoiding the undesirable yellowing of fibres. Sodium silicates ( water glass ) as a stabilising agent, ph buffer and complexing agent. Optional additives such as chelating agents etc. As the bleaching effect of hydrogen peroxide is often insufficient with the deinking process, a final bleaching after deinking is carried out in most cases. This can be done by oxidation (e.g. using hydrogen peroxide) or by reduction (e.g. using hydrosulphite). 1 Hannuksela, T.; Rosencrance, S. Deinking Chemistry, 2 Faul, A. The Deinking Process, 3 Particularly in North America, washing processes are also used as an alternative to flotation. For further information, please consult the corresponding specialist literature (e.g. ref. [1] and ref. [2]). process - Durst news for the science and application of inkjet printing - Issue 85 - June

7 Science & Technology Pulping and flotation as key stages. The key chemical stages of the relevant deinking process occur in the pulper and/or the flotation cell. The use of a sodium hydroxide solution produces hydrolysis and hence the breakdown of the ink layers (see figure 2), while the accompanying swelling of fibres facilitates the separation of the printed layers from the substrate. Figure 2. Hydrolysis caused by a sodium hydroxide solution results in the breakdown of the ink layers; here, acrylate ink is shown as an example. A certain degree of fibre swelling also has a positive effect. Fatty acids ( soaps ) and synthetic surfactants are at least as important here; their main task is to separate and disperse the hydrophobic ink layers and/or their decomposition products from the substrate and remove them from the system as foam is formed within the flotation cell (see figure 3). In addition to conventional fatty acid salts (i.e. soap products of palmitic acid, stearic acid, oleic acid etc.), synthetic surfactants based on ethoxylated fatty acids, propoxylated fatty alcohols and block polymers derived from these are increasingly being used. In this connection it should be noted that there is no generally applicable optimal composition of the blend 4 of fatty acids and/or surfactants for the deinking process. Instead what is needed is for this to be tuned to the process, the materials to be recycled and, where applicable, the relevant stage of the process. Figure 3 (a) Figure 3 (b) Figure 3 (c) Figure 3. (a) Principle of ink detachment from the substrate by applying soaps and other surfactants (from ref. [1]). (b) Formation of foam is essential for flotation. The detached ink layers are encased in micelles, floated in the flotation cell and then removed from the system (from ref. [2]). (c) Technical design of flotation (from ref. [ 5 ]). 4 Further de-inking additives can also be used, e.g. modified inorganic particles (MIPs) as substance collectors in the flotation process. The use of enzymes for the breakdown of ink layers is also described in several references (see ref. [1]). 5 Fischer, A. Recycling Inkjet Inks: Does water-based mean eco-friendly?, 19th European Inkjet Printing Conference process - Durst news for the science and application of inkjet printing - Issue 85 - June

8 Science & Technology Critical aspects On the basis of the above statements, it could be concluded that the recycling of printed paper and cardboard primarily requires (i) efficient separation of the printed layers from the fibres, and (ii) complete removal of the separated printed layers from the system. Although these basic assumptions are correct, the following additional points should be considered in practice, as they significantly impact the efficacy of flotation and hence the deinking result: 5 1. The substances/particles/pigments to be removed must be solid in form The substances/particles/pigments to be removed must be of a certain particle size (greater than 10 µm). Taking account of the typical pigment sizes of UV inkjet inks (d 90 values between 200 and 250 nm), the necessity of developing advanced flotation and deinking techniques soon becomes obvious. 3. The substances/particles/pigments to be removed must be as hydrophobic as possible; however certain hydrophilic surface features are required in pigments, for example, in order to ensure good dispersion properties in the liquid ink. 4. The selection of surfactants and other chemicals must be optimised and matched to the material to be recycled. This means that the requirements for efficient deinking processes to some extent contradict the requirements for formulating stable, pigmented UV inkjet inks. Hence, it is not surprising that the deinking of inkjet printed paper and cardboard proves to be difficult and challenging in practice. In particular the presence of so-called dirt specks in the recycled material (see figure 4) still represents a problem to be solved which requires new and innovative approaches in the future. Figure 4. Inkjet-printed paper before (left) and after (right) flotation. The presence of dirt specks still represents a problem to be solved. Summary and outlook This article has discussed the basic stages of deinking processes. In particular, pulping and flotation have a key role to play here, where a combination of mechanical and chemical processes is applied to achieve separation of the ink layers from the material to be recycled, enabling them to be removed. Although deinking seems to be simple in theory - and it has been well researched - the use of increasingly smaller-ground pigments and similar, also sets new challenges for the corresponding processes. For example, the further reduction of dirt specks is essential, but cooperation between ink manufacturers, equipment manufacturers for deinking processes and paper and cardboard producers must be pushed further in future in order to make the efficient recycling of printed paper and cardboard materials possible. However, the success of the relevant R&D work is not only important for inkjet printed media, but the deinking of analogue printed materials will also benefit, because even the recycling of conventional printed materials is subject to complaints regarding dirt specks and/or insufficient whiteness. 1 Hannuksela, T.; Rosencrance, S. Deinking Chemistry, 2 Faul, A. The Deinking Process, 3 Particularly in North America, washing processes are also used as an alternative to flotation. For further information, please consult the corresponding specialist literature (e.g. ref. [1] and ref. [2]). 4 Further de-inking additives can also be used, e.g. modified inorganic particles (MIPs) as substance collectors in the flotation process. The use of enzymes for the breakdown of ink layers is also described in several references (see ref. [1]). 5 Fischer, A. Recycling Inkjet Inks: Does water-based mean eco-friendly?, 19th European Inkjet Printing Conference 6 This also means that printed layers on the basis of water-soluble dyes are not suitable for flotation. process - Durst news for the science and application of inkjet printing - Issue 85 - June

9 Media & Handling Printing corrugated boards and cardboards with Durst Rho flatbed printers simple, reliable, trouble-free Corrugated boards and cardboards are produced in a wide variety of different qualities. In many cases the sheets are already damaged on the pallets before and during transport. They are often printed, stamped and folded as bulk goods using flexographic, silk screen and offset processes. The damaged edges are simply trimmed away and treated as waste from the outset. Small batch sizes and the individualising of packaging and displays call increasingly for the use of digital printing techniques which combine excellent quality with the flexibility needed to get orders out on time. Typical damage in transit Dished sheets of corrugated board These corrugated sheets some of them delivered with damaged edges still have to pass smoothly through the Durst Rho flatbed printer during contactless digital printing. Now Durst has developed corrugated board options for its Rho flatbed printers. A powerful vacuum acting beneath the conveyor belt and side guides called skis because of their shape keep the sheets flat and prevent any skewing. The side guides can be adjusted vertically and horizontally to suit the sheet s thickness and size. For medium-sized batches there is a fully automated sheet feeder for the Rho 1000 which has been developed for the stable feeding of sheets to the printer. Side guides for the Rho 700 to 900 series Vacuum belt and side guides for the Rho 1000 Series Fully automated sheet feeder system process - Durst news for the science and application of inkjet printing - Issue 85 - June

10 Media & Handling Starting from the pallet, the sheets are picked up by lifting suckers which adapt to suit the undulating surface, and then registered sheet by sheet with pull and push lays before printing. Lifting suckers - adapt to the wave of the sheet Lifting sucker, detail Pull lay A video of the corrugated boards option of the Rho 1000 can be viewed on YouTube at process - Durst news for the science and application of inkjet printing - Issue 85 - June

11 Application The Firma Group used a Durst Rho 750 to create the panels for an exhibition in Venice of the photographic work of Ferdinando Ongania Advanced technology, professionalism, versatility and personal service are the hallmarks of the Firma Group, whose headquarters are in the province of Venice. The company was founded 12 years ago and is now a leader in digital and offset printing and paper manufacture in Italy, particularly in the Veneto region. The young and dynamic Firma Group was created by four partners all with previous experience in this market sector. From the synergistic combination of their technical knowledge, a business was developed which was able to offer a great many services organised into various specialised divisions, with a broad and very complete array of products. The core businesses of the Veneto concern are the divisions devoted to paper manufacture and digital printing. On the latter the Firma Group has staked a great deal, whilst relying on Durst technology. With a pioneering spirit and a wish to supply contemporary ideas to respond to customer needs, the Firma Group was one of the first to believe in digital printing on rigid media and opted for a Durst flatbed system. Maurizio Centenaro, group partner, comments: In 2004 we installed the first Rho 205, immediately recognising the great efficiency and reliability of the system. Customers liked the many uses of the printer, with the consequence of a progressive growth in demand. This was the reason that we again invested in Durst technology in 2010, purchasing the Rho 750 Presto flatbed. The machine included 6 colour printing plus white, which is important in producing fine image quality on a number of materials such as rigid media with a black background or cardboard. We are pleased with the performance of Durst systems, both in terms of productivity, with its ability for continuous printing, and the automation of workflow. The system is proving to be extremely reliable and fulfills all our expectations, so well in fact, that, whilst aware of the great reputation of Durst technical assistance, to date we haven t needed to test its efficiency. The new FirmaGroup headquarter Managing Director Maurizio Centenaro with the new Rho 750 Presto Using the Rho 750 Presto has certainly helped to further increase the company s business, thanks to the guarantee of extremely high quality printing. Our portfolio, Centenaro continues, includes advertising agencies, communication firms and direct customers, who often require quite complicated workmanship. A good example of this is the request from the Procuratoria of St. Mark in Venice, in the person of architect Ettore Vio, who chose the Firma Group to create over twenty panels sized up to 150 x 300 cm to support the exhibit: Ferdinando Ongania. St. Mark s Basilica , a very complex project that, through an extraordinary gallery of images, shows visitors the late 19th century studies of the church by publisher Ferdinando Ongania, an iconographic means to document the state of the monument and to preserve it. Reproduction of the mosaic printed on black gatorfoam in white and 6 colours process - Durst news for the science and application of inkjet printing - Issue 85 - June

12 Application Published between 1881 and 1893, Ongania s work seemed revolutionary at the time and made Venice the centre of photographic publishing. It introduced such innovative techniques that, in a publisher s note on the work, Ongania wrote: One is delighted to have been the first to have created, in the most splendid and decorous way, a monument of modern graphic art worthy of the great treasure it illustrates, the Golden Church. More than a century later, the challenge was to faithfully reproduce some of Ongania s original prints. The Firma Group enthusiastically accepted the commission, knowing that it had an ace up its sleeve in the form of Durst technology, which would certainly match the impressive job. We used white and above it 6 other colours, choosing Gatorfoam Nero as a media, explained Centenaro. The Rho 750 ensured high definition of the details and was faithful to the original chromatics. The result was truly amazing and, if I may quote Ongania, saying how delighted we were to have contributed to this great project. Reproduction of the Basilica di San Marco (Venice) printed on black gatorfoam in white and 6 colours Printed Dibond totem with a description of the work The exhibition stand was also printed and personalised using the Rho 750 All rights reserved on images and illustrations. Durst is a Registered Trade Mark Durst Phototechnik AG Large Format Printing Vittorio-Veneto-Straße Brixen, Italy Telefon Telefax info@durst.it process - Durst news for the science and application of inkjet printing - Issue 85 - June