As is generally the case with the use of digital print technology, it is often not a case of simply using digital instead of conventional methods to provide the same end result. Digital printing can often be seen as complementary to conventional processes, for example in over-printing customised data on conventionally printed packaging. But it should also be seen as the enabler of entirely new capabilities, which could never have been considered using conventional printing methods.

Digital inkjet technology is particularly well-suited to packaging. It can easily be integrated into a production line without creating significant disruption and introduces high-quality graphics to enhance the finished product.

Packaging market structure

The market for package printing in all its forms exceeds US$200 billion. Printed packaging accounts for about half of all packaging. The corrugated container segment produced and shipped about 117 billion square metres of material in 2003. The packaging industry produced just over 100 million tonnes of containerboard in 2003. Other packaging segments include flexible, folding carton, rigid, labels, multi-wall sack, sanitary packaging, plastic packaging container, metal can, glass container and miscellaneous packaging. 

Market demand and product competition have prompted the production of more colourful and eye-catching packaging. Food containers include bags, bottles, cans, cartons, cups, jars, pouches, tubes and tubs. Materials include glass, metal, paper and paperboard and plastic. This segment produces about US$50 billion worldwide. Beverage can and bottle producers label over 220 billion metal cans and over 250 billion glass and polyethylene terephthalate (PET) bottles.
 
Print processes for packaging

Most cans and containers receive labels. Flexography and lithography currently account for almost all package printing. Screen-printing produces specialty labels and some direct container decoration. Pad printing decorates complex curved containers. Inkjet, mostly continuous but also including piezo drop-on-demand (DoD), provides date marking and coding for food and beverage containers. Electrophotography and inkjet can supply short-run and individually numbered labels for this segment. Inkjet's ability to print without contacting an object offers promise for direct printing on flats and simple curves for short to medium production runs.

The growth of shopping club warehouses where corrugated shipping boxes serve as product displays has prompted manufacturers to demand more colourful and eye-catching images from their box suppliers. High-speed inkjet printers that are about to arrive in the market can address these needs. Scitex designed its CORjet for this market, and has already placed units to print boxes with up to six water-based colours. UV-curable ink printing flatbeds from Azero, Durst, Inca, Océ, Vutek and others also offer solutions for customised and short-run box printing.

Inkjet for packaging

Packaging marking companies have used inkjet systems to label and code boxes for decades. Packaging companies have used continuous and piezo inkjet printers for over 30 years. ITW's Trident piston DoD piezo inkjet printheads have printed reliably and successfully in the high-paper lint industrial environment of cardboard stamping and converting plants. Also Xaar, Spectra and Hitachi DoD piezo printheads decorate packaging. Hewlett-Packard (HP) has targeted the packaging market with its thermal inkjet through licensed use of its TIJ 1.0 and TIJ 2.5 printheads.

The packaging industry has started to purchase and use digital solutions for full-colour applications and not just for monochrome marking. For example, US company Menasha Corporation, headquartered in Neenah, Wisconsin and with plants in 13 US states, acquired the Scitex Aprion piezo inkjet system, CORjet. The six-colour water-based inkjet printer uses seven of the unique Aprion Magic 512-nozzle printheads per colour, or 42 printheads and 21,504 nozzles per printer. Each nozzle can generate over 25,000 droplets per second. The device can print corrugated card and other rigid materials up to 10mm thick. Reportedly it can print 40 sheets per hour, size 2.6 x 1.6m (i.e. 160m2 per hour). It prints 600dpi for text, line art and barcodes, and up to 300dpi for graphic images. 

Menasha says it is now able to run small quantities of 50-1,000 custom or market-targeting images cost-effectively, without the front-end printing image preparation expenses associated with analogue. It enables quick response and fast turnaround, reducing to hours or days projects that required weeks with analogue printing. Other packaging companies are following the Menasha lead and are advancing digital marking and decorating solutions.

Primary packaging

For primary packaging, the ideal solution requires the label to be printed onto the package in-line with the filling process. DoD is probably the only technology capable of doing this, although there are still some issues to be overcome to achieve an acceptable quality and performance. With the possibilities of achieving 360dpi resolution and eight or more levels of greyscale, and printheads using CMYK process colours with the possibility of adding two further colours - orange and green - to give a hexachrome result, the door is open for most key brand items to be handled this way. When all these factors come together, the impact will be to reduce inventories and achieve a shorter time to market by being able to print on demand to the standards required.

Case coding

Inkjet printing is extensively used in the packaging arena for very fast coding and marking devices for the production of "best before" dates on products. For this type of process, continuous inkjet technology is normally used because it has a faster linear speed and can print over a longer flight distance onto highly curved surfaces such as bottles and cans. However, the quality of output is less than can be obtained by using DoD to achieve higher resolution, and higher rates for area coverage, by using many more nozzles to print smaller drops at a lower linear speed.

DoD vs continuous

As customer expectations for colour graphics increase, DoD comes into its own by using wider printheads to include both text and graphics output in a single pass. Printing heads are now being produced up to 70mm wide to meet the demand for high-quality print at speeds of up to 60m per minute. Companies such as Domino and Weber are meeting the demands of the retail industry that could not have been met by the use of traditional case coding printing methods.

The introduction of two-dimensional and colour barcodes are two examples of work where very high resolution is needed. Printing magnetic codes onto secure documents and cards is another example. When UV-curable inks are used, it is possible to introduce microlenses from transparent ink to facilitate reading by different sorts of optical devices - creating a process more akin to reading a CD on the side of the package.

As continuous inkjet systems use water-based inks, which cost up to 80 per cent less than solvent and UV inks, developments in continuous inkjet systems will have an increasing impact in wide- and grand-format applications. The projections also indicate that their use in photo kiosk applications will secure a significant market share.

The use of inkjet as a printing

technology is seen by many to have the most growth potential. Print speeds and resolutions are anticipated to increase by up to 100 per cent, while consumable costs will decline by 25-55 per cent.

The future of inkjet for packaging

The larger format inkjet press is finding limited acceptance for producing folding cartons, while the narrower inkjet press is having more success in the label market. Label presses number about 12 in North America and about 40 in Europe.

Printing speeds in packaging

Press speeds have increased from 8m per minute to close to 18m per minute, and are expected to increase to close to 40m per minute or greater by 2005. Print resolution has risen to 600dpi with enhanced screening patterns that can give high-quality output for most packaging applications. They have the ability to print six or more colours (12 colours with duplex printing), which may include CMYK and white. This makes them suitable for printing labels and flexible packaging that require a first-down white.

Segmentation

The segmentation of the packaging industry has had both a positive and negative effect on the development and acceptance of inkjet printing in packaging. With companies specialising in niche applications, there is no single company providing the full spectrum of package printing services. Companies developing inkjet printing solutions are working with companies providing conventional services to develop a system, but it would be focused at a particular niche market. Typically, this incremental development has been more frequently applied to digital printing solutions in the label market than in the folding carton market.

Tag and label

The tag and label segment accounts for about 70 per cent of all package printing done digitally to date. Much of the early R&D by digital printing systems developers focused on the label market because it was the most easily adapted to the capabilities of the systems in their early stages.

Inkjet printing of labels is now becoming a reality as inks and substrates become compatible and production machines such as the Mark Andy/Dotrix lines come on stream. There are a number of machines and inkjet technologies applied to the labelling of packaged products.

The applications they are used for include:

• Printing four-colour onto cardboard cases and trays using Xaar XJ500 printheads, while still in their flat-sheet form - these products are aimed at supermarkets for secondary package printing (Kappa Packaging, Eindhoven);
•  Barcoding and marking solutions on primary packaging using Domino print heads using oil-based inks at speeds up to 0.5m/sec;
• Printing directly onto cans, with variable data (CanPet AG, Switzerland);
• Document printing inkjets for variable data - that could be fitted to a flexo line to allow for greater customisation (MIKOH Imaging Systems, Australia);
• Printing of graphics, logos, barcodes and multi-line printing at up to 200dpi at 45m/min using coding and marking inkjets (Codent Limited, Stockport, UK);
• Coding and marking for mailing applications, using solvent-based inks, at 185dpi, with a print speed of 100m per minute (HS Automatic ApS - Haas 100).
  

The marketplaces these products are aimed at include:

• Pharmaceutical;
• Food/beverage;
• Cosmetics;
• Household;
• Industrial;
• Major applications;
• Self-adhesive;
• Blister packaging.
  

Inkjet technology, when integrated into the end user's manufacturing line, is seen as a growth market. It is estimated that 60-70 per cent of the Fortune 500 consumer goods companies are exploring the use of inkjet technologies in their packing lines.

The food and beverage sector will continue to use inkjet printing's ability to individually number and code containers. It will also explore digital printing for special promotions and time-sensitive labelling; promotional labelling is a valuable tool in capturing customer interest, sales and loyalty.

Some major companies are using remote digital printing facilities to produce labels and insert materials within their packing plants worldwide. This will continue to gain popularity as broadband communications become commonplace and should become a mainstream practice by 2007. Label production is the most adaptable to this practice.

Flexible packaging

Flexible packaging accounts for about 20 per cent of all packaging printed digitally to date. Aiding acceptance by users is the ability to inkjet white inks and the rectangular nature of most flexible structures. The strength of the conventional flexible packaging market will aid acceptance of inkjet printing in this segment. Inkjet technologies will dominate the systems producing flexible packaging digitally in 2007. Besides labels, flexible packaging may be the area where inkjet printing is technically the easiest adaptable application to be added to a packing line for the incorporation of any variable data. This practice should begin taking hold by 2005 and become well-established by 2007.

Corrugated packaging

The corrugated packaging market accounts for a fraction of all digital packaging to date. Until 2001 there were no mainstream efforts to implement inkjet printing in this market. One of the wildcards to the acceptance of inkjet printing on corrugated packaging is how online and catalogue companies choose to implement it.

Point-of-purchase

Like the corrugated segment, the point-of-purchase (PoP) market is virtually untapped, accounting for a very small amount of inkjet printing to date. It also has great potential for inkjet printing in the future.

Cost reductions

As with any technology, cost reductions are likely to occur as the technology evolves. This usually happens when steps are taken to remove a process from the workflow. Removal of any man/hour-related operations over a two-year period generally help to justify the original capital investment decision.

When productivity gains are scored from one (least important) to ten (most important), consumable manufacturers rate consumption levels slightly higher as a factor leading to cost reduction. Also rating highly are enhancements in production technologies and reduced raw material costs. Costs of inkjet printing systems and related costs are falling. The most significant trend, however, is that of increased productivity. By 2007, the productivity of inkjet printing systems will increase by as much as 400 per cent. There are many issues related to these productivity gains. The main enabling factor is the implementation of inkjet printing technologies into packaging and manufacturing lines, coupled with the huge growth predicted for the wide-format sector.

Finishing

There is debate as to where inkjet printing should be integrated into finishing lines. Most systems offer some level of finishing in-line such as varnish, die-cutting, hot stamping or UV treatments. Finishing technologies have matured greatly over recent years and continue to be more productive. As end-users begin to implement inkjet printing in their packing lines, finishing will become part of the overall process. Technologies such as laser die-cutting and RFID technologies will be integrated into production lines that include inkjet printing. Inkjets may even be used to spray on the transistors used in the circuitry for the RFID products.