The Printing Industry, As Innovative as Ever
The dynamism in the printing and packaging industry is simply astounding. We continue to see the industry evolve through emergence of new technologies, needs and businesses. Take for instance printing. Printing traces its origins to a little before 220 A.D. when woodblock printing emerged in China. More than 1800 years later we continue to see innovations and improvements in printing technology.
As with any other business or industry, sustainability is a hot topic in the printing industry, too. Water-based inks, which help lower emissions and harmful VOCs compared to solvent-based inks, are predominantly used on porous substrates such as paper, folding cartons and corrugate. Besides being more environmentally friendly, the lower VOC content translates to lower flammability and worker health concerns. Hence the safety measures that need to be put in place for using water-based ink resins are fewer and less expensive. However, flexible packaging comprising of films and foils largely utilizes solvent-based technologies. This is because when it comes to printing on film and foil, water-based inks tend to have lower print speeds and quality of print compared to solvent-based alternatives.
However, this is starting to change. Advances in ink resin technology and printing equipment are enabling greater adoption of water-based printing on flexible packaging with fewer compromises. Resins impart important characteristics to the inks. Unlike solvent-based resins, water-based resins tend to have poor resolubility and resistance properties. Poor resolubility causes drying of the ink in the anilox rolls, eventually leading to dirty print. Fixing this issue requires stopping the press and cleaning the rolls, resulting in a loss of productivity for the printers. To boost resistance properties, crosslinkers may be added press side. Oftentimes the crosslinkers used are extremely toxic to the press operators and tend to be very expensive, not to mention wasteful due to severe limitations on usability of ink over long runs.
Further developments in the self-crosslinking resin technology have improved the resolubility and resistance performance of water-based inks greatly. More improvements are underway to help reduce and maybe even eliminate the use of toxic crosslinkers altogether. At the same time, newer technology in the form of polyurethane and acrylic dispersion hybrids have emerged to support the strong growth witnessed in laminated flexible packaging.
Flexible packaging formats such as pouches provide improved barrier performance and shelf life but require inks that have higher bond strengths to prevent delamination. Acrylic dispersions typically print well but have poor bond strengths and vice versa with polyurethanes. With hybrid dispersions, printers no longer need to compromise on either bond strengths or printability. More importantly, what this has meant, is that water-based inks can be used to print packaging for meat, cheese, salty snacks etc. which are reverse-printed before being laminated.
Another fascinating and rapidly evolving area in printing is digital printing. The proliferation of SKUs is leading to shorter run lengths and making digital printing more viable than ever. Of course, the adoption is also aided by rapid advances in printing equipment and technologies. In fact, the digital printing segment of the industry is poised to see some of the higher growth rates in the industry, especially when it comes to packaging.
Make no mistake though, the adoption of inkjet printing is still in its infancy when it comes to packaging. It is most widely adopted on labels and starting to see greater usage with folding cartons and corrugate. As with analog printing processes, inkjets can be either solvent, water or energy curing based technology. UV inkjets are widely used when it comes to labels and packaging. However special considerations apply when using this technology. Typical concerns with UV inks are potential odor and migration of harmful substances, especially if the ink is not cured completely. Due to the low viscosity of the inkjets and the presence of reactive diluents in the UV inkjet inks, it becomes necessary to utilize precoats or primers when working with porous substrates or sensitive packaging applications. Primers help prevent the ink from penetrating deep in to the substrate and not curing when exposed to the energy curing stations. Also, in case of non-porous substrates they help with providing receptivity to incoming inkjets which often have challenges with adhesion.
As printers look to adopt digital printing and inkjets more widely, water-based UV inkjets may become more relevant. While water-based inkjets have challenges with adhesion and UV inkjets may have concerns with potential migration, water-based UV inkjets eliminate the need for reactive diluents and photoinitiators. This helps eliminate or lower the potential for migration of harmful substances and odor issues.
There is much activity on the regulatory front, too. There is an increasing interest in knowing what raw materials go into the inks that are used to print packaging. There are a number of regulations and guidance such as FDA, Swiss List, Nestle’s list of harmful substances etc. to be considered before deciding what raw materials or inks may be suitable for certain packaging applications. This, in turn, is leading to technologies and products which are more compliant and safer for use in packaging.
As the packaging industry evolves, so too will printing. One can’t help but get the feeling that despite evolving and improving over more than 1,800 years, the printing will remain as dynamic or may be even more so in the coming years.