Marketing No More VOCs: Waterless Offset Printing Japanese material technology expert Toray Industries, Inc. has developed the first printing system that is completely VOC-free. Used in flexible packaging printing, it can keep workers safe without compromising printing quality. The demands placed on flexible packaging manufacturers are growing. Packaging should be more environmentally friendly, more cost efficient – and all that while delivering superb printing quality and being safe for consumers and workers alike. On top of that, the food industry is seeing a general trend towards a diversification of products, resulting in smaller printing runs. The use of the right printing method plays a major role in meeting these expectations. But flexographic and gravure printing, the established industry standards, are increasingly reaching their limits in accommodating some of these aspects. VOCs: Harmful to workers and the environment One such puzzle that has been plaguing the industry for years is how to avoid volatile organic compounds (or VOCs) in the printing process. The term encompasses a variety of gases and small particles that are released during the production, use, or even storage of certain products, such as cleaning liquids or paint – with harmful consequences on both the environment and the workers Workers at printing plants come into contact with VOCs at various touchpoints interacting with VOCs. Long-term exposure with VOCs can lead to anything from eye and throat irritation to loss of coordination, chronic fatigue, or even cancer. In flexible packaging printing, VOCs occur mainly through the use of solvents in inks and the cleaning liquid used on the printing presses. In cases where conventional offset printing is used, the dampening water becomes an additional contributor of VOC. And while the environmental harm of VOCs has largely been contained through air filters in printing facilities, the detrimental effects on workers’ health remain. Although significant strides have been made in reducing VOCs, it was not possible to avoid them completely – until now. One solution to rule them all Toray Industries, Inc. has developed the first ever printing system that is 100 percent VOC-free. What is more, the solution makes no compromises in printing quality or food safety. One key to achieving this is the use of waterless offset printing with Comexi’s CI8 printing press. In offset printing, the inked image is transferred – or offset – from a printing plate to a blanket made of rubber, which in turn transfers it onto the printing surface. While this printing technique has become an established method in such fields as newspaper printing, label printing, plastic card printing and others, it is still relatively unheard of in the flexible packaging world. Yet, offset printing comes with a number of features ideally suited for the present challenges in flexible packaging printing: Offset printing plates are a lot easier to produce than the cylinders required for rotogravure printing or photopolymer plates for flexographic printing. This allows more flexibility in terms of short-term printing, facilitating smaller printing jobs at a low cost point. Furthermore, the use of waterless offset printing can already reduce the amount VOCs by up to 80 percent compared to conventional offset printing. However, conventional offset printing, the most common offset printing method, is fairly limited in the choice of substrates that can be used. Moreover, conventional offset printing requires dampening water to repel the ink in places that are not printed. The stained dampening water becomes a source of VOCs and also creates waste water that subsequently needs to be purified before further use. Thus, while conventional offset printing comes with a number of advantages in terms of flexibility and economy, it cannot fully eliminate VOCs in the printing process. Bringing waterless offset printing to the flexible packaging industry To forego this issue, Toray is relying on a technology that the company has been successfully working on for decades: waterless offset printing. In 38 food Marketing & Technology • February 2021
Marketing on-site tests, the Comexi CI8 offset printing press could easily be adapted to this environmentally friendly version of offset printing. Here, a silicone polymer is used as an ink repellant instead of a dampening solution, eliminating one major source of VOCs. Inks and cleaners: Completing the puzzle The test also featured the second central element of Toray’s new printing solution: water-washable EB inks. Reducing VOCs in inks has been a goal of manufacturers for a while, resulting most recently in the introduction of water-based inks. The concentration of organic solvents, the main contributors to VOCs, is between five and 30 percent in these inks – compared to up to 80 percent in regular oxidative inks. However, a remnant of VOCs remain, not only in the ink itself, but also in the liquids used for cleaning the printing presses. These require the use of organic solvents in order to eliminate any remaining ink, and they contain relatively high levels of VOC. A waterbased cleaning liquid could alleviate this problem – but it can only be used with the new kind of water-washable EB ink developed by Toray. The ink itself does not contain any organic solvents, making it completely VOC-free. At the same time, the combination of special ink formulation and waterless printing achieves a particularly strong adhesion to a wide variety of substrates. These special inks are cured using an electron beam (EB) instead of UV light and therefore do not include any of the photo-initiators limited by food packaging regulations. Consequently, there is no risk of any VOCs or photo-initiators migrating into the printing substrate. The new solution is therefore particularly safe for food packaging. Finally, water-washable EB inks allow the use of water-based ink cleaners. As this cleaning process is mostly done by hand, it is the most significant factor where workers still come into direct contact with VOCs. Eliminating harmful particles here is therefore especially important to maintaining workers’ health. Together with waterwashable EB inks and waterless offset printing, these water-based cleaners form the first completely VOC-free printing system in the world. The future of flexible packaging printing is VOC-free With the combination of waterless offset printing, water-washable EB inks, and water-based cleaning liquid, Toray’s new printing system is the first in the world to be completely VOC-free. And it has already been put to the test. A European converter completed a series of tests to print OPP, PA boil, and PET retort pouches with Toray’s technology and a Comexi CI8 press – with resounding success. However, the Japanese material technology specialist is not merely hoping to offer flexible packaging manfuacturers a more sustainable and healthier alternative – the solution is also meant to bring superior printing quality. This sentiment is expressed in the brand name P4E, which in future will include all VOC-free printing solutions. The name stands for “Epoch-making, Ecology, Excellence and Efficiency” for the printing industry. An ambitious goal that the company is alread planning on expanding. “We want to move towards contributing to a circular economy in flexible packaging printing and help achieve the Sustainable Develeopment Goals (SDGs) set by the United Nations”, Toray Industries, declares. In keeping with the company’s own sustainability vision, Toray has contunuously been seeking technical developments that will help create a greener future. Recycling has been one dream in the flexible packaging world for some time. In order to make it a reality, Toray Industries’ film business segment is currently working on applying mono-material subtsrates to the process. At the same time, the company is hoping to extend VOC-free printing to other printing segments, as well. Thus, Retort packaging samples using Comexi CI8 press and Toray’s novel printing system Toray is working to provide the right solutuon for the future of flexible packaging – more sustainable, more adaptable, and just as high-quality as the currently leading solutions. fmt The Author Mr Takayuki Kamei is General Manager, Electronic Information Materials Division, Toray Industries, Tokyo, Japan food Marketing & Technology • February 2021 39
