Due to the many advantages offered by flexible pouch packaging, its use is forecasted to grow significantly in various fields.
The Toyo Ink Group is a pioneer in flexible food packaging materials and has been developing related technologies in cooperation with food manufacturers and package converters since the 1970s. Some of its latest advances in flexible packaging are expected to fuel the demand for these convenient packages.
High Colour Strength Water-based Flexo for High-speed Printing
Water-based flexo inks have taken a big leap forward in recent years. New developments in reducing VOC emissions, complying with regulations and international brands’ global standards and addressing odour issues, have been driving global demand for water-based flexo inks, including in Asia where gravure is the dominant process.
Up to now, due to some limitations such as slow bonding rates and poor printability, water-based inks have mostly been used for absorbent paper board applications while solvent-based inks have been the product of choice for plastic films. However, recent innovations in water-based flexo inks compatible with reverse printing offer high colour density and high lamination strength that run well at high press speeds.
Toyo Ink’s AQUA LIONA NF flexo ink, which made a breakthrough debut at drupa 2016, is one of the first eco-friendly, water-based inks to be specially formulated for reverse lamination printing in applications such as food packaging. Capable of withstanding temperatures up to 120°C, AQUA LIONA is well suited to the demands of retort pouch processing.
Conventional water-based inks for flexible packaging usually print at speeds of 100m/min to 150m/min depending on the drying equipment. AQUA LIONA NF recorded coating speeds of 500 m/min (1640 fpm), taking water-based printing to a new level of output. This breakthrough was achieved by leveraging Toyo Ink’s advanced ink dispersion technology to produce inks with higher color density (or strength). The higher density results in a smaller anilox cell volume at levels that are closer to the industry standard for solvent-based flexo printing. Smaller cell volume translates into less ink that needs to be evaporated, which in turn results in a fast drying rate - a must for high-speed printing. Thus AQUA LIONA NF offers greater printing mileage with less ink and less time needed to dry.
In addition, high colour density allows printers to use high-resolution screening plates with more than 59 lines/cm (150 lpi), which will produce better printed images. The polyurethane resin of AQUA LIONA NF imparts stability and strength to the ink layer, lending to its high-speed printability and excellent levelling.
In the past, water-based flexo inks had not been the best available option for printers and converters as it did not meet a wide range of applications from snack to boil and retort (120°C) pouch applications across multiple substrates. Thanks in part to Toyo Ink’s proprietary PU system, AQUA LIONA NF demonstrates high lamination capabilities and stability on a broad range of substrates, making it suited to lamination and other reverse jobs on PET, OPP and nylon films. As for printing stability, it is reflected by excellent levelling and dot reproduction on plastic films even during high-speed printing.
100% VOC Free EB Flexo Printing for Flexible Packaging
In recent years, electron beam (EB) technology has been rapidly penetrating the flexible packaging market. As the food packaging market rapidly grows, regulations become stricter. The demand for lower migration inks is also expected to rise in Europe, US and other parts of the world as the brand owners escalate packaging safety requirements as paramount. In such an increasingly strict regulatory environment, EB inks and coatings have been garnering greater attention as they are considered to be the optimum materials for food packaging. Unlike UV, they are free of photoinitiators and fast-curing with low migration potential.
Closely focused on the development of EB technology for flexible packages, like pouches, Toyo Ink introduced in 2017 the Elex-one FL series, a completely 100% VOC free EB curing system for flexo printing with a unique ink composition designed to eliminate VOCs and water content to zero.
In addition, the company developed a wet-trapping technique for EB-curable flexo inks that undergo an instantaneous transformation of the surface of the laid-down wet ink and prepares its surface to accept the next layer of wet ink upon transfer from the anilox to the substrate. This transformation enables an ink layer to hold subsequent ink layers on top of each other without interstation dryers.
The trapped inks (in a CI flexo press system) are cured with a single EB unit at press end. Elex-one FL cures using only EB irradiation—without the addition of a volatile component. Such an innovative system not only eliminates the need for inter-station dryers, thus significantly reducing the energy needed to dry the inks compared to thermal drying, but it also offers a non-flammable pressroom environment and an emissions-free technology platform for flexible package printing. Some of the EB flexo inks out on the market today contain small traces of solvent or water that is chemically added into the ink to facilitate wet-trapping. With Elex-one FL from Toyo, however no solvent or water is needed. As a result of this, there is no change in consistency or solid %. Since ink curing does not occur on the plate, stable print quality can be achieved even over long runs.
Transparent Pouches with Improved UV Blocking
The flexible materials that are often used for food packages incorporate aluminum foil and metal deposition films to block ultraviolet (UV) rays. However, this means the contents cannot be seen. Transparent films help to reassure consumers by making the interior visible. They also reduce costs and resource consumption during the production process.
The Toyo Ink Group has been working to improve the laminating adhesives that bind plastic films together as well as the coatings that help to prevent UV degradation. The Group has developed a UV coating that cuts ultraviolet rays (200 to 380 nm) by 95% or more. These and other advances are making it possible to preserve food for longer without compromising safety.
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