We are now frequently asked about using films as packaging materials more economically and in some cases, simply to label directly. Is it really that easy?
Dr. Ulli Nägele: With direct labelling, the fear always exists that constituent parts of the adhesive from the label can “migrate into” the food. One thing should be made clear at the outset: tested label adhesives, which are approved for food, do not contain any toxic or dubious substances. But nevertheless, food manufacturers and vendors naturally want as few substances to enter into the food as possible. The “migration” of such constituent parts has therefore been occupying the food industry for a very long time. However, film is not necessarily a barrier, especially not if the food (or other products) contains fat. The solvent properties of fat particularly favour the migration of substances - also right through films. That is why films with specific barrier properties have been used in the past. These films are composites of several layers made up of various materials. However, to ensure the recyclability of such forms of packaging, they will be comprised of a monofilm in future, which can be submitted for recycling after use. This means that the film will take on even less of a barrier function in the future. If the film packaging is omitted completely, the label adhesive naturally needs to have even lower migration.
In the past, there have also been very low-migration labels. However, the lower-migration the label became, the worse the self-adhesive properties became - and vice versa. But poor self-adhesive properties are not an acceptable compromise for the food industry. Safe labelling and traceability are essential, particularly as the labelling process often comes with difficult conditions, such as cool ambient temperatures and high-speed applications. Multi-layer technology for adhesive labels offers a way out of the dilemma. During the course of coating, two different adhesives are applied at the same time. The characteristics of these adhesives can be controlled independently, resulting in stronger adhesion, even on difficult surfaces, and low migration.
On the basis of multilayer technology, we have been able to develop adhesives which don’t migrate through prevalent PE plastics in spite of the required initial adhesion. For example, in standardised tests according to the European standard EN 1186, the adhesive with the name 63Mps achieved outstanding results: for tests by a well-known test institute, the migration values were below the determination limit. The film used in these tests, which is made of polyethylene (PE), was extremely thin and consequently particularly susceptible to migration. We expected that we would achieve low migration values with 63Mps. However, it was quite a sensational discover that we were able to achieve such good migration values under the conditions referred to. With this, the label users are on the safe side.
Mind you, multilayer products are not innovative, expensive specialist adhesives, but rather, standard adhesives, with well-known adhesion and processing characteristics. Thanks to the differently formulated, second and/or intermediate layer, they now provide added value, for example, they have low migration, but retain their excellent processing characteristics.
An important requirement from politicians and scientists is to use recycling even more intensively and to view it as an even bigger opportunity. What role can labels play in this?
HERMA pursues three approaches:
1. When it comes to submitting plastic packaging to real recycling (and not down-cycling, for example), the label and/or its residue-free removability takes on a key function in the meantime. If all impurities can be removed from the plastic packaging at the same time as the label, i.e. particularly printing inks, clean granulate will be obtained in its most valuable form. However, how can the balance be struck between secure adhesion of the labels and their removal later on without leaving residues? The innovative multilayer technology is again used for this. With this, actual product characteristics, which initially contradict each other, can be combined and the use of cost-intensive specialist materials can be reduced. We are able to allocate specific characteristics to any adhesive layer that is used. In this case, the label must adhere securely, but must be able to be removed without leaving residues in the standard washing processes. Therefore, the label is not part of the problem, but rather, the solution. That is why, when it comes to recycling plastic packaging, there is no getting around multilayer adhesive systems, in our opinion.
2. We will introduce an innovative labelling system without a carrier strip. It will be officially presented at Labelexpo and FachPack 2019. This system will expand the application fields of so-called linerless labels dramatically. Label users no longer need to worry about the proper disposal or recycling of substrate materials. These are simply no longer needed. This is a strong argument when it comes to the sustainable use of scarce resources. Detailed information about the new linerless system will be available in late summer.
3. In such cases where linerless systems are not technically possible, the substrate material of labels becomes a desirable raw material. In 2010, HERMA was the first self-adhesive material manufacturer that no longer submitted siliconized release liner to an actual recycling process. This occurs in close cooperation with Cycle4Green, which has developed a specialist process for separating the silicone. The Austrian paper manufacturer Lenzing, which has substantial experience in paper recycling, produces fine and specialist papers from this, among other things. The former release liner is turned into high-quality label paper - or back into release liner. In 2018, using the remains of release liner collected and recycled there alone, HERMA made its entire fleet of 78 cars quasi CO2-neutral. The calculation behind this is: according to the certificate from Cycle4Green (C4G), in 2018, HERMA submitted around 201 tons of release liner that was no longer required from adhesive material production to specialist recycling. With the help of C4G and the Austrian paper manufacturer Lenzing, this is turned into label paper or back into release liner, both of which are used again by HERMA, amongst other things. If these products were to be produced from fresh fibres in the same quantity, in comparison to recycling, around 406 more tons of CO2 emissions would have been generated. By comparison, the entire family company's fleet only generates CO2 emissions of just under 400 metric tons. HERMA is calling for all label printers and users to also take part in the C4G recycling initiative. After all, it is worthwhile - not just for the climate. It also contributes to curbing the continuing increase in costs of raw materials.
A series of approaches exist in the packaging industry, with bio-based materials. What is happening at HERMA in this respect?
With adhesion material for paper labels, we use paper that is FSC or PEFC certified, i.e. it is sourced from sustainable forestry and is bio-based. With thermal papers, we are now able to supply papers that manage entirely without chemical developers. With films, we will be supplying a PE film soon, which is made of recyclate.
But the term “bio-based” should not be used indiscriminately. With biofuels, there is already the provocative question of fuel or plate. And it would certainly also be dubious to clear jungles for cultivating corn plantations, which, in turn, are for the purpose of producing “bio”-naphtha - the starting material for “bio-based” polyolefins.
How do you see the classic labels in comparison to new trends, such as laser direct labelling or smart labels? Are we at the beginning of a new age?
It appears to be slightly exaggerated to us, to speak of a new age. The possible range of labelling technologies has increased significantly. But alternatives to labels have always existed. The label is universal and can be used extremely flexibly and designed in a variety of ways. The technology is basically fully developed and many industries are experienced in the use of self-adhesive technology. The costs are also manageable. We can establish that labels are constantly advancing into new niches and applications. For this, labels, their adhesives and naturally also the dispensing technologies must constantly be developed further. But HERMA has been putting the way that this works to the test for decades. And we are continuously growing.
Late-stage customisation, personalisation and lot size 1 are an interesting trend in packaging print, not least, because only what is actually needed is printed. What can adhesive material from HERMA contribute to this?
If labels are personalised or produced in smaller lot sizes, they are usually printed digitally. For this, the label material needs to meet specific requirements. For example, many of our products can immediately absorb UV-hardening inks and produce an excellent print image, thanks to optimum ink adhesion. Print solutions with water-based inks are also being increasingly used, because it is particularly economical for very small print runs. However, they often need a specialist paper coating, which can absorb the ink better. HERMA has developed a specialist product range for this, which delivers outstanding printing results on the inkjet printers available on the market, such as Canon, Epson, HP, Trojan etc., with both sheet-fed and web printing. These materials are also ideally suited for the ultra-fast Memjet technology, which combines the benefits of an inkjet printer with its static, page-wide print head. Appropriate film from us can even be printed on in a way that is saltwater-resistant (according to BS5609 Section II and III). In principle, HERMA can supply the appropriate adhesive material for any form of digital printing.
Do you sense a growing awareness of environmentally-relevant aspects when you speak with printers or label users?
In addition to the respective individual problem-solving, there is an increasing focus on the subject of sustainability - we are definitely noticing this. I have already explained HERMA's approaches to this above. Furthermore, the “migration”, which has already been described, has been an important issue for many years, above all, naturally, in the area of food, cosmetics and pharmaceuticals.
