New Breakthroughs in Electron Beam Ink Technology for Flexible Packaging
The main value drivers that continue to lead the global packaging market are operational efficiency, food packaging safety, reduced energy consumption, cleaner work environment, and a greener earth (lower CO2 footprint). While these drivers have prompted the flexible packaging industry to explore and deploy high-performance, refined solvent-based inks and solvent recycling technology, innovative water-based inks and so on, gaps to cover all these drivers still exist. By leveraging its expertise in polymer and chemical synthesis, the Toyo Ink Group is looking to fill these gaps with its recent advances in electron beam (EB) curable ink.
First of all, what is EB curing?
EB curing uses high-energy electrons to dry the printed ink at the end of the press. The curing chemistry involves direct cross-linking of the ingredients (i.e. monomers and oligomers) within inks and coatings. The accelerated electron energy ensures that a high degree of conversion from short-chain oligomer to long-chain polymer (polymerization) takes place, thus instantaneously curing the printed surface without the use of heat or light. EB curing is a cold process so it is brilliantly suited to the conversion of thin, heat-sensitive flexible packaging films.
Breakthrough in non-evaporative wet trapping
In 2017, Toyo Ink research labs in Japan solved the technical challenge of non-evaporative wet trapping in flexo with the development of an EB-curable ink system for CI flexo printing: The Elex-one™ FL series. Since other contemporary, conventional EB flexo inks contain a small percentage of volatiles (solvents and water), a small trace of such ink components may evaporate during printing. This necessitates the continuous addition of lost components to retain print quality and often leads to discrepancies in ink stability and quality during printing.
In contrast, Elex-one is a completely non-volatile ink so there is no concern for the evaporation of volatile materials. This allows for a fire-safe and VOC-free work environment and ensures stable viscosity and consistency of inks for the whole print run. Thus, this new ink enables a completely solvent-free and water-free printing technique where each ink layer is applied on to the substrate without any back-trapping or mixing of inks—all this without the aid of interstation dryers.
Advantages of Elex-one EB flexo inks
Elex-one brings tremendous advantages to the flexible packaging industry:
•High press stability: 100% solids and non-volatile. Ink viscosity and consistency do not vary, resulting in consistent print quality.
•Easy operation: No drying on the plate for easy plate cleaning. No solvent evaporation results in no change in ink solid % and easy ink maintenance during printing.
•Lower energy consumption: No interstation or final dryers are required, eliminating the need for emission control/collection equipment.
•Low carbon footprint: Zero VOC emissions.
•Workplace safe: Non-flammable and no hazardous vapor concentrations
The main factor hindering the widespread use of EB systems is the cost. As such, the adoption of this technology has remained the realm of large‐
scale production. That said, when compared to other processes deployed in flexible packaging printing EB installations require less in terms of operating costs, material use and maintenance, thus balancing out the total cost equation. Also, a post-cure odor from the film may pose a concern for food packaging applications.
EB applications of today
EB technology has found a niche in applications where low odor and low migration are a must, such as food and drug packaging. Toyo Ink’s EB products continue to show strong growth in Europe for the surface printing of snack food packaging or yogurt lidding, as well as in baby diapers and other sanitary products.
Source: ToyoInk Co., Ltd.'s Packaging Materials Department.