A Closer Look at Electron Beam Technology
by John E. Salkeld
PCT Engineered Systems, LLC
Illustration shows a cut-away diagram of the vacuum chamber of an electron beam system.
Ebeam technology instantly cures ebeam-friendly inks, coatings and laminate adhesives on paper, film, paperboard or metal.
During the EB-curing process, electrons are generated in a vacuum chamber and then propelled through a thick foil onto the target substrate to effect curing.
Question: I hear my printing colleagues discussing electron beam technology. What is it?
Answer: Electron beam technology – known as EB or ebeam – is a technology that uses electrons to alter the molecular state of a targeted material or surface. In the ebeam process, clouds of electrons are generated inside a vacuum chamber, which then are accelerated through a thin, metallic foil window and are directed onto a moving printed web surface. The inks, coatings or adhesives that react to ebeam are made up of molecular elements known as monomers and oligomers. These accelerated electrons connect these molecules into longer-length polymers, instantly changing their chemical composition from a wet state into a dry or solid state.
Question: How is it applicable to the printing industry?
Answer: Ebeam continues to be a growing topic among printers and package converters because it instantly dries – or more accurately, cures – ebeam-friendly inks, coatings and laminate adhesives on paper, film, paperboard or metal. It is a growing alternative to oven (thermal) drying and ultraviolet (UV) curing for a number of reasons discussed below.
Web offset printing presses have been equipped with ebeam units for many years. EB-curable ink technologies also exist for flexographic and gravure printing. As is the case in most of the printing industry, EB-curable inkjet is generating significant interest and is very likely to grow rapidly.
Plus, in recent years, printers and package converters have discovered that ebeam can be used not only to cure inks, coatings and adhesives, but also as a useful tool to give extra eye appeal to packaging.
Question: How can ebeam be used for package decoration?
Answer: As the printing, label making and converting industries grow and become more versatile, so does ebeam. Beyond curing and crosslinking, a recently developed 4-in-1 converting line allows package printers to utilize ebeam systems to create innovative package designs. Visual enhancements offered by an ebeam package decorating system include overprint coating, laminating, cold foil transfer and Cast & Cure holographic embossing.
Ebeam provides instant curing of coatings and adhesion of laminates to a packaging surface, providing a high gloss and inherent durability that is not possible with other curing technologies. Packagers take advantage of increased package brightness and strength capabilities to give products a new visual pop, while reducing package abrasion and breakage risks.
With cold foil transfer, an ebeam-curable adhesive is applied to a substrate in registration with printed graphics and then is ebeam-cured with an overlying metalized film. The metal transfers to the cured adhesive areas, producing a strong visual metallic effect. Nearly any type of hot or cold stamping foil may be used in an ebeam cold foil process.
Finally, Cast & Cure is a decorative coating process that integrates casting and curing to provide a consistent high-quality finish. It can generate ultra-high gloss, matte and holographic images onto a variety of substrates. This environmentally friendly process helps make packages more recyclable by eliminating the laminated, metalized films used in traditional holographic processes. Additionally, this casting film is reused multiple times, achieving substantial cost savings.
Ebeam package decorating systems are designed for use with web-printed packaging materials, including flexible packaging, folding cartons, labels and multi-wall bags. These systems work at high speeds, are compatible with wide web widths and generate low substrate heating, which is important when utilizing sensitive flexible packaging materials, such as thin films.
Question: Is ebeam technology a new trend in printing?
Answer: People unfamiliar with ebeam technology are amazed by the concept of curing surfaces by altering molecular structures instead of thermally evaporating solvents or water. They even are more shocked when they learn that this radical technology is more than 40 years old! The reason ebeam continues to grow in popularity is twofold: first, the systems and ink/coating/adhesive formulations necessary to achieve ebeam curing continue to fall in price as the technology gains popularity and second, ebeam offers a number of key benefits over thermal drying and UV curing.
Question: What are the ebeam advantages over thermal drying and UV curing?
Answer: In general, ebeam benefits that printers and converters have documented include improved product performance, superior product consistency, higher process throughput and greater energy savings.
Specific to thermal drying, ebeam curing offers several significant benefits, including the following:
- Ebeam systems take up much less space than ovens, which can, in some cases, be hundreds of cubic feet in size. Some converters that have replaced ovens with an ebeam system find enough floor space has been freed up to put in a new line.
- Ebeam systems generate very little heat in the substrate being targeted, making it a solid choice for printers and converters over thermal and UV curing (and, it sometimes is the only option) for treating heat-sensitive materials like thin films (such as those found in shrink sleeve labels).
- Ovens require an enormous amount of energy and are staggeringly expensive to operate and maintain. There have been studies that have shown that, in some cases, an ebeam system requires up to 95 percent less energy than the oven it replaces.
- Finally, ebeam systems help contribute to workplace safety and comfort. With no need to remove solvents from inks and coatings, ebeam curing eliminates the volatile organic compounds (VOCs) that are associated with thermal drying.
Specific to UV curing, ebeam curing also offers several significant, but different, advantages. These include the following:
- By definition, UV curing requires photoinitiators to complete the curing process. Photoinitiators are toxic and run a slight, but nonetheless real, risk of migrating into food. Ebeam curing does not need photoinitiators to work and thus poses no potential for migration. This makes ebeam extremely popular among food package printers and converters.
- Ebeam curing has proven to work particularly well when curing thick, opaque and/or high-density ink and coating layers vs. more conventional UV curing methods.
- Like thermal drying, UV curing produces a significant amount of heat. In certain cases, ebeam curing has been shown to require up to 80 percent less energy than UV curing.
- Unlike UV bulbs, whose power declines over time, ebeam curing offers extremely precise processing, with a stable energy output that does not drift over time.
Question: Is ebeam technology always the best choice for curing?
Answer: No, not always. As has been mentioned, ebeam is the “go-to technology” if there is food packaging involved; sensitive substrates that might be damaged by heat; or thick and/or opaque inks, coatings or adhesives that need to be cured. But, not every printing process benefits by using ebeam curing. For instance, PostPress magazine – and most other commercial printing jobs – wouldnt benefit by having its inks cured using ebeam technology.
Question: What is the takeaway?
Answer: Ebeam systems have grown increasingly popular in the converting industry, both as an alternative to traditional curing methods and in their newest role of applying innovative package decoration. Package converting continues to put up powerful numbers in an economy that many still consider in recovery, and analysts predict that strong growth will continue for quite a while.
Printers and package converters who arm themselves with versatile technologies like ebeam to help differentiate their new products and evolve their production techniques promise to see some very exciting times in the print and converting industry in the years ahead.