Last week I wrote about the Signite labelling system that Actega has developed, concentrating in that first story on the printing of the Signite labels. For this story I’ll cover the other half of the process, the application of the labels to the containers.
As we’ve seen, the Signite approach essentially involves printing the graphic to a carrier film via a flexo or hybrid press, and then using a separate applicator to transfer the graphic to a container. For now, once the graphic has been transferred the used carrier film is discarded as waste. Tony Carignano, technical director of marketing at Actega North America, says: “A reusable plastic-based carrier film is currently being explored. However, our ultimate goal is to be a single-use plastic-free label decorating solution. Our current release coated polypropylene-based plastic carrier film is not reusable.”
He continues: “We will be transitioning to a thinner gauged PET-based Signite carrier film by 2022. Based on brand owners’ feedback, the ultimate goal is to adopt a release-coated cellulose carrier. Super calendared kraft paper and glassine are also commonly used as carriers in narrow web label printing and therefore, being researched by our team too. Our concern, however, is that reusing a plastic carrier film will drive up carbon contribution because the film will need to be shuttled between the Signite hardware applicator point of use and the printer, typically in separate locations. There is also the rewinding accuracy and cleaning aspects of re-using a plastic film which further contributes to energy and labour costs. All of this needs to be taken into account as we explore the options available to get us closer to our goal. We hope to evaluate the environmental impact of all release-coated carrier film scenarios over the next year as a Signite life cycle analysis is assembled and externally validated.”
There are a couple of steps to applying a Signite graphic and so Actega has developed an applicator device that can take the printed roll and transfer the graphics to a bottle in a single process. Carignano explains: “The process relies on pressure during transfer. In most cases, the container needs to be slightly pre-heated in order to get good adhesion of the pressure sensitive to occur.” The system can process around 35 to 40 bottles, assuming a standard 750cl wine bottle size, and can apply decoration up to 20cm in diameter.
Signite has been designed for use with glass and plastic bottles such as PET and HDPE though Actega mainly seems to be concentrating its efforts on glass bottles from higher value applications such as wine and spirits bottles as well as those used in perfumes and essential oils. This adds its own challenge as the bottles used in perfumes and essential oils are much smaller than those used for wines so the process has to accommodate a range of sizes.
Once applied, the Signite graphics appear to have quite good scratch resistance. Carignano explains: “It really comes down to how you formulate the L3 layer which is the clear layer. The clear layer basically is made up of oligomers and monomers so it’s selecting the right types of oligomers chemically as well as with the functionality in those oligomers to make sure that you have a very robust scratch resistance surface to work with.”
There’s no issue with de-inking as the inks are not mechanically imaged directly onto the surface. Carignano explains: “We have designed it so that it will wash off of glass containers at a certain temperature range as well as at a certain PH range, anywhere between 11 and 13, and the temperature range is 140 up to 160º F which is what you commonly would find in an industrial bottle washing operation.”
This is an important point because there’s obviously a role for increased use of glass bottles if we are to deal with our over-reliance on plastics for packaging. That could include reusing glass bottles, much in the way that many Western countries used to reuse milk bottles. But it’s also worth noting that crushed glass from recycled bottles can be used to lower the cost of making new glass. To this end Actega is actively working on a project in California to improve glass recycling to benefit the large wine making sector there.
Carignano points out that Signite is a viable alternative to direct to object printing, noting: “With direct to object printing you would either have to put down a print receptive coating first of all or you would have to trick out the ink system. If it were a photopolymer ink system you might have to basically cheat and put some organic solvents in it to get good coalescence as well as adhesion to the surface of the glass. But in our process we are using a pressure sensitive adhesive to adhere to the surface of the glass.”
The applicator includes a set of flameheads, about four inches high, for working with glass bottles, where the trick is to apply a quick blast of heat fo rip to 25 seconds to the glass surface just before applying the Signite transfer. This helps to clean the surface by ablating any dust away. But it also softens the cold end coating that is added to all types of glass to prevent it from easily picking up dirt and oils and from quickly turning grey and cloudy. This cold end coating is typically a form of polyethylene though Carignano says that Actega has come across a few cold end coatings that use a different base and behave differently.
He explains: “We have to soften the polyethylene up and we do that by flashing flame on it. When we soften it slightly there’s a goldilocks zone of temperature where we know that we can very easily transfer the PSA pressure sensitive adhesive over to that polyethylene and as the PSA starts to cool down we believe you are getting some type of mechanical hinging, with the pressure sensitive adhesive on to the surface of the glass so that it doesn’t easily come off the glass.”
He adds: “So with photopolymer chemistry, when you crosslink the chemistry, because you have photo initiators in it you get somewhat of a reticulation, so you are linking up the monomers with the oligomers based on their functional tropes so you are creating a homogenous film because you pass the UV wavelengths of light through that, the photo initiator sets off a free radical reaction where it comes from a semi-fluid to a solid state and that’s how we create the robustness of the outer coating with our process.”
He adds: “With direct to object printing you get reticulation so you are constantly fighting reticulation on the surface of the glass where you really don’t want reticulation, so shrinkage is a bad thing for direct to object printing whereas with us we have a jelly layer that we use so that even if the image starts to slightly reticulate that’s OK because we have the jelly layer underneath it that supports that image while it might slightly shrink. That jelly layer, which is the pressure sensitive adhesive, is kind of like your shock absorber, hinging the image onto the surface of the glass.”
Time to market
Carignano says: “Our plan moving forward, at least for the next two and a half to three years, is to use the press that we have, the new Mark Andy hybrid digital press, that we just purchased at the beginning of 2021 to do the production of Signite for the market. The name of the game is to generate money and as we can prove internally to senior management as well as to the market that this is a technology that is adoptable and has value in the market place, at that point it makes sense for us to go out and start training up outside printers and converters on the technology.”
He points out that the proliferation of e-commerce has created a niche market of small brands that don’t have enough volume to outsource to a screen printer and would benefit from the opportunity to prototype their solutions using the Signite technology. It also allows Actega to promote the concept, whilst looking for partners and training operators.
He adds: “We realise this is not normal for an ink and coating company. We are printing and decorating and moving into a new universe. How do we remain relative as a manufacturer of inks and coatings and adhesives moving into the world of e-commerce as that grows? How do we engage with brands in the right way and be nimble with our technologies so that we have something that’s relative when there’s a need for it in the market, based on legislation, the need for recycling and what have you?”
He continues: “At the end of the day, we want to sell fluids. We are really not in the business of selling hardware. We would be interested in collaborating with OEMs of inline decorating hardware, not only in the US but Europe too. But at the end of the day our core competency is selling inks, coatings and adhesives into the market and being a subject matter expert on the direct and indirect food contact compliance and regulatory requirements for those chemistries sold into the market.”
At the moment, Actega is placing its equipment with multiple partners in the United States and Canada. These include glass decoration houses as well as glass bottle manufacturers and some smaller brands in North America. For now this equipment is only certified for use in North America though Actega is looking into the certification process for CE codes that would be necessary to expand into Europe, and is hopeful of doing that next year.
Clearly this is a technology that’s worth keeping an eye on, not only for the visual effects that it can produce but also for the questions that it raises around the use of plastics and sustainability within labelling, issues that are guaranteed to become more important in the coming years. In the meantime you can find the first half of this story here, and further details from actega.com.